@proceedings {JRN55398, title = {Ecological science infrastructure for sustainability transformations in rangelands}, year = {2022}, month = {1/28/2022}, abstract = {Sustainability transformations{\textemdash}deliberate and radical shifts in values, governance, and management regimes to achieve sustainability{\textemdash}are needed in rangelands as in other components of the Earth system. We review four concepts comprising an ecological science infrastructure to support such transformations. The foundation is standard measurement of rangeland conditions in the field, especially vegetation and soil properties that underpin the environmental aspects of sustainability. Big data resources, especially gridded spatial datasets produced by models and remote sensing, can be combined with field data and computational approaches to upscale information about rangeland conditions and produce additional indicators of ecosystem functions and services. State and transition models (STMs) linked to land types provide a means to interpret indicators and link interpretations to sustainable land management practices to manage change. Technologies for climate adaptation in rangelands also need to be linked to STM databases. Web and mobile technologies can put multifaceted science knowledge into the hands of pastoralists worldwide to support transformational changes in how rangelands are managed.}, author = {Brandon T Bestelmeyer and Jeffrey E. Herrick and Joel R. Brown and Dawn M. Browning and Bulgamaa Densambuu and Emile H. Elias and Sarah McCord and H. Raul Peinetti and S. Spiegal and Nicholas Webb and Jebediah C. Williamson} } @conference {JRN55350, title = {An extreme precipitation event, abrupt grass recovery, and soil processes in the Chihuahuan Desert}, booktitle = {Ecological Society of America (ESA)}, year = {2022}, month = {07/11/2022}, abstract = {Landscapes in the northern Chihuahuan Desert have been undergoing a gradual shift from perennial grassland to shrubland over the past century, driven primarily by the legacies of historical disturbance events and ongoing aridification. Nonetheless, extreme high rainfall periods can result in instances of remarkable grassland recovery, although they are highly patchy. In one area on the USDA-ARS Jornada Experimental Range, abrupt grass recovery occurred in an eroding Prosopis glandulosa shrubland state in response to a high rainfall period (2007-2009){\textemdash}an event that we did not imagine could happen. We are comparing ecosystem processes in this {\textquotedblleft}recovered savanna{\textquotedblright} to 1) patches of grassland that are in a relatively unaltered {\textquotedblleft}reference{\textquotedblright} state and 2) patches of shrubland state in which grass recovery did not occur. We asked a) is the recovered savanna similar to the reference grassland with respect to structure, composition, and vegetation-soil feedbacks and b) what led to spatial variation in grassland recovery? We compared vegetation and soil chemical and physical properties at twelve replicate study plots in each of the three states: recovered savanna, reference grassland, and shrubland. In addition, we are monitoring soil volumetric water content and aeolian sediment flux within each state. ~ We found that although the species composition of grasses differed strongly between reference grassland and recovered savanna, ecosystem functions measured were largely similar between these states but differed from shrubland states. Infiltration rate, soil aggregate stability, soil organic carbon, and soil C:N ratio were typically similar between reference grassland and recovered savanna but often far higher than in shrubland. Large bare gaps between plant canopies in the shrubland enabled far higher aeolian sediment fluxes than in the reference grassland and recovered savanna where bare gap connectivity was smaller. Static (edaphic) soil properties and volumetric water content in recovered savanna were intermediate between reference grassland and shrubland, suggesting that sites experiencing grass recovery may have been predisposed to grass establishment by virtue of their topoedaphic settings, yet were not resilient enough to avoid grass loss in the first place. The recovered savannas persist after a decade (including extreme dry years), provide ecosystem services comparable to the reference grasslands that originally occupied these sites, and are superior to the shrublands that they recently replaced. The question before us now is how to encourage more shrubland to savanna transitions.}, keywords = {abrupt grass recovery, Chihuahuan Desert, extreme precipitation event, soil, soil processes}, author = {Brandon T Bestelmeyer and Matthew Levi and Neeshia Macanowicz and Heather L. Throop and Nicholas Webb} } @proceedings {JRN55419, title = {The economic costs of wind erosion in the United States}, year = {2022}, month = {12-9 to14-2022}, address = {Chicago, IL}, abstract = {Wind erosion negatively impacts many aspects of society, but its socioeconomic costs in the United States were last assessed comprehensively during the 1990s. It has been over three decades since and both the climate and society have changed greatly. Solar panel and wind turbine usage have risen drastically, and an infectious disease known as Valley fever that is linked to soil (and thus likely dust) has been growing in incidence. Windblown dust has also caused an increase in transportation fatalities. Due to these and other changes, we decided to re-assess the previous estimate of $10 billion annual cost of wind erosion from Pimentel et al. (1995). We examined existing literature on past cost estimates and used domestic research data when possible. Some cost estimates, such as dust morbidity, were directly taken from past studies and adjusted for inflation if necessary. Other estimates, such as loss estimates from renewable energy generation, Valley fever, and transportation costs were built from the ground up. Values for energy generation, Valley fever cases, and transportation costs were drawn from their respective government sources, such as the Department of Energy, the Centers for Disease Control and Prevention, and the Department of Transportation. The data were then modified by findings from other studies (i.e. percentage of loss attributed to dust), enabling total costs to be calculated with the cost per increment, such as the cost of one KWh of wind energy or the cost per motor vehicle crash. We found that with the most conservative parameters, windblown dust cost the U.S. at least $69 billion in the year 2017. This $69 billion estimate is likely an underestimate as other factors were not accounted for, such as airport delays and increased desertification. This study serves as an updated baseline estimate for the cost of wind erosion, but further detailed research needs to be conducted to create a more complete cost estimate for the United States. }, keywords = {economic costs, renewable energy, society, solar panel, turbine, valley fever, wind erosion}, author = {Irene Feng and Daniel Tong and Thomas E. Gill and Scott Van Pelt and Nicholas Webb} } @proceedings {JRN55360, title = {Explorations of heritage vs conventional cattle in a changing climate}, year = {2022}, month = {2/8/2022}, abstract = {Multiple lines of evidence suggest that heritage Raramuri Criollo (RC) cattle, a biotype with over 400 years of naturalization in the harsh landscapes of the Mexican Copper Canyon, could offer producers a novel means of meeting sustainability and production goals on southwestern rangelands in the face of a rapidly dwindling forage supply and a hotter, drier climate. Compared to conventional breeds (e.g. Angus), RC cows and steers have been documented traveling farther per day and exploring larger areas over multiple seasons, ecosystems (Chihuahuan Desert, California chaparral, and Colorado Plateau), and physiological states. Likewise, RC cows have a lighter body weight and tend toward more even grazing distribution and fewer re-visitation rates during critical periods of the year when rangelands are most vulnerable to overgrazing - suggesting a potentially lighter footprint on soils and vegetation. Raramuri Criollo cows, compared to conventional counterparts, express a unique {\textquotedblleft}follower{\textquotedblright} mothering style, which allows cows more freedom for daily exploration. Rararmuri Criollo also tend to exhibit better heat tolerance by maintaining/regulating internal temperatures, possibly because of body size, hair length, hide color, and behavioral tendencies. Use of RC genetics may present production opportunities related to reduced supplemental feed inputs and potentially lower overhead costs compared to conventional counterparts, while still producing marketable crossbred calves that wean and finish at saleable weights with acceptable carcass traits. This assemblage of studies suggests that RC genetics could be well suited to emerging climate change driven conditions on southwestern ranches because of their unique foraging behaviors and physiology, different resource requirements, and theoretical ability to produce more pounds of weaned beef per pound of cow vs conventional biotypes. Future work will seek to determine what role RC cattle might serve in mitigating climate change impacts and how they could fit into niche and conventional beef production systems. }, keywords = {cattle, changing climate, explorations, heritage vs conventional}, author = {Matthew M. McIntosh and Macon, L. and Matthew Redd and Andr{\'e}s F. Cibils and Richard E. Estell and S. Nyamuryekung{\textquoteright}e and S. A. Utsumi and Amy L. Gonzalez and Andrew Cox and G. Duff and Schallner, J. and S. Spiegal} } @proceedings {JRN55382, title = {Evaluation of water quality benefits of manureshed based manure management in the Susquehanna River Basin}, year = {2022}, month = {7/16/2022}, abstract = {The {\textquoteleft}manureshed{\textquoteright} concept is aimed at generating sustainable manure balanced systems by connecting crop areas (nutrient sinks) with livestock agriculture (nutrient sources). This study aims to quantify the potential water quality benefits derived from manureshed based nutrient management through scenario-based analyses in the Susquehanna River Basin (SRB) using Soil and Water Assessment Tool (SWAT). Three manure management scenarios were accessed based on the manureshed concept - (i) Baseline scenario assuming minimal manure transportation, manure generated in a HUC-12 is distributed in the same watershed, (ii) Manure Balanced scenario that considers no excess manure application, excess manure in a HUC-12 watershed is transported to nearest available sink watersheds; (iii) Optimized Priority scenario that assumes manure is fully transportable and manure is not applied in vulnerable areas. The manure application rates were estimated considering both N based and P based crop nutrient demands, totaling six manure application scenarios. The crop N demand-based manure application apply excess P and P based application needed supplemental N inorganic fertilizer application to meet crop nutrient demand. Evaluation of manureshed concept-based manure redistribution scenarios indicated a decrease in nutrient loads at the watershed outlet and an improvement in nutrient uptake by the crops. The N based manure balanced scenario estimated 6\% and 26\% reductions in organic N and nitrate loss, respectively compared with baseline scenario having the same quantity of total manure applied in the watershed. P based manure balanced scenario simulated 4\% reduction in nitrate loss in comparison to the baseline condition. The N and P based optimized scenario simulated 25\% and 15\% reduction in nitrate loss respectively when compared to baseline scenario. For phosphorous, N and P based manure application in manure balanced scenario indicated a reduction of 9\% and 11\% sediment P loss, respectively when compared with the baseline. In optimized priority manure application scenario, the model estimates indicate 12\% and 19\% reduction of sediment P loss from the baseline for both N and P based manure application respectively. The scenario evaluations indicate that the manureshed concept provides an opportunity for sustainable manure management with increased nutrient use efficiency.}, author = {Amartya Saha and Gourab Saha and Raj Cibin and S. Spiegal and Peter J. A. Kleinman} } @conference {JRN55404, title = {Ecological transformations in desert grasslands: resist, accept, or direct?}, booktitle = {Society for Range Management Meeting Abstracts}, year = {2021}, month = {12/05/2021}, abstract = {The transformation of many rangeland ecosystems is inevitable, necessitating new frameworks to guide management decisions. We describe ongoing transformation in desert grasslands of southwestern New Mexico using century-long vegetation monitoring and climate datasets from the Jornada Experimental Range and monitoring of recent restoration actions. These datasets indicate undesirable, irreversible changes from historical benchmarks but include some potentially desirable outcomes. We use these datasets to consider management decisions via the resist-accept-direct (RAD) framework. Considering directional changes in climate and ecological thresholds, managers can respond to the trajectory of change by resisting (working to maintain or restore based upon historical or acceptable current ecosystem conditions), accepting (allowing an ecosystem to change without intervening), or directing (actively shaping ecosystem change toward preferred new conditions). We describe a logic for RAD decisions in rangeland management and restoration based on a consideration of climate and ecological processes.}, author = {Brandon T Bestelmeyer and Erica M. Christensen and Laura M. Burkett and Matthew Levi and Leticia Lister and Neeshia Macanowicz and Nicholas Webb} } @article {JRN55287, title = {Effects of managed fire on a swale grassland in the Chihuahuan Desert}, journal = {Rangelands}, year = {2021}, month = {07/27/2021}, pages = {1-4}, abstract = {On the Ground {\textbullet} Fire is considered a critical process for limiting shrub encroachment and maintaining grassland structure and functions. {\textbullet} Fire can be detrimental to grasses in upland settings of arid desert grasslands, but no studies have been performed in more productive swale grasslands. {\textbullet} Monitoring of a prescribed fire treatment in a swale grassland in southern New Mexico indicated that perennial grasses had not recovered after 5 years, even with above-average rainfall. Furthermore, indicators of erosion susceptibility increased, and shrubs resprouted rapidly.}, keywords = {ecological site descriptions, prescribed fire, state and transition models, vegetation monitoring}, doi = {10.1016/j.rala.2021.05.001}, url = {files/bibliography/21-022.pdf}, author = {Brandon T Bestelmeyer and Laura M. Burkett and Leticia Lister} } @conference {JRN55399, title = {An evaluation of soil heterogeneity and representativeness within and across sites in the NEON network}, booktitle = {ESA - August 2021 meeting -Virtual}, year = {2021}, month = {3/1/2021}, abstract = {Background/Question/Methods The National Ecological Observatory Network (NEON) provides coincident hierarchical and ecologically meaningful measurements made at diverse U.S. ecosystems designed to answer key ecological questions at the national scale. Comprehensive soil properties are critical to characterize the geomorphic template at NEON sites from which the multi-scale and -taxa ecological observations arise. Physical and chemical soil properties play an important role in ecosystem function; spatial variation in soil physical and chemical properties is expected to influence ecosystem dynamics, nutrient cycling and myriad ecological processes. We report on a standardized, nationwide soil characterization effort at NEON terrestrial sites designed to describe how soils vary within and among NEON sites and to provide contextual information to support the long-term biodiversity sampling program. Sampling for the NEON soils characterization project was done at distributed plots at 46 of 47 terrestrial NEON sites via a modified stratified sampling design. In addition to broadly describing these soils data for the ecological community, we posed the following questions: How representative are NEON distributed soil pedons of soils in the surrounding landscapes?; and how does variability in soil properties within NEON sites range across the network? Results/Conclusions~ NRCS soil scientists collected and processed samples for 715 pedons constituting 3,246 horizons across the NEON network. Eleven of twelve soil orders were identified from the described pedons, with only Oxisols (a tropical soil) absent from the network. A total of 560 pedons were described from soil pits with the remaining 155 described from soil cores. Of the 3,246 horizons, 10.4\% were classified as organic horizons, with the remaining mineral horizons comprising top soil (A, 26.8\%), eluviated horizons (E, 6.8\%), subsoil (B, 48.7\%), parent material (C, 18\%), and bedrock (R, 2.1\%). The distributed pedons vary in how closely the descriptions correspond with existing Soil Survey data. Similarity in soils beyond NEON site boundaries ranged from highest coincidence in the Mid-Atlantic, Central and Northern Plains domains to lower correspondence in the western U.S. and Tundra and Taiga domains in Alaska. Alaska{\textquoteright}s low correspondence is due to missing data where soils have not been mapped. High agreement areas have either more similarly described NEON soils (as in the mid-Atlantic region) or more homogenous mapped soils (as in the Great Plains). Regions of low correspondence between NEON soils and the surrounding area represent an opportunity for future exploration through NEON{\textquoteright}s relocatable sites or collaborative projects with outside researchers. }, author = {Dawn M. Browning and Stanish, Lee F. and S. W. Salley and Dave Kinsbury and David L. Hoover} } @article {JRN55318, title = {Ecological theory and practice in arid and semiarid ecosystems: a tale of two LTER sites}, volume = {59}, year = {2021}, pages = {151-180}, publisher = {Archimedes (New Studies in the History and Philosophy of Science and Technology)}, abstract = {The chapter compares the conceptual history of two Long Term Ecological Research (LTER) programs at U.S. Department of Agriculture (USDA) research sites established following land overuse in the early 1900s. Early USDA studies were based on a Clementsian model, where vegetation following disturbance was expected to return to the climax determined by climate and soils. Management-based alternatives to the Clementsian model were developed after the dominant vegetation failed to recover and alternative states were observed. The Central Plains Experimental Range LTER (later Shortgrass Steppe LTER) program began in 1981 at a site in northern Colorado. Early studies focused on the inability of the dominant species, blue grama (Bouteloua gracilis), to recover on long-abandoned agricultural fields. These observations were in contrast to the resilience of blue grama-dominated ecosystems in response to livestock grazing and drought. The Jornada Basin LTER program began in 1982 at a Chihuahuan Desert site in southern New Mexico, where black grama-dominated (Bouteloua eriopoda) grasslands converted to shrublands following livestock overgrazing and drought. Early Jornada studies focused on the causes and consequences of this desertification. In collaboration with USDA scientists, the two LTER programs developed new research ideas and approaches which brought an improved understanding of historic dynamics and nuance to the Clementsian-based paradigm. New paradigms also reflected the importance of objective, long-term studies and the dynamic, multi-scale nature of these arid and semiarid ecosystems. Comparing two LTER programs at research sites sharing a conceptual basis, but with different ecosystem properties, can provide insights into the development of US grassland ecology over the past century.}, keywords = {arid ecosystems, desertification, drought, Ecological climax, grassland ecology, International Biological Program, livestock grazing, long-term ecological research, LTER program}, isbn = {978-3-030-66932-4}, doi = {10.1007/978-3-030-66933-1_6}, author = {Debra C. Peters} } @article {JRN55242, title = {Exotic oryx interact with shrub encroachment in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {184}, year = {2020}, month = {09/2020}, chapter = {104302}, abstract = {Biotic invasions can interact with on-going landscape transitions in introduced ranges, acting synergistically to accelerate landscape change. The African oryx (Oryx gazella), a large ungulate native to the Kalahari Desert in southern Africa, was intentionally released into the Chihuahuan Desert of southern New Mexico to provide increased hunting opportunities. Oryx have subsequently dispersed widely, including into the adjacent Jornada Basin Long Term Ecological Research site, which contains native grassland communities imperiled due to shrub encroachment. We examined how landscape use and diel activity of oryx interacts with shrub encroachment at Jornada Basin. We hypothesized that oryx would be more common on unencroached grasslands that provide preferred forage, and that oryx would be most active at dawn and dusk (crepuscular) when ambient temperatures were favorable and predator surveillance was possible. We sampled 24 sites across a broad gradient of shrub encroachment from 2014-2018 using camera traps to evaluate our hypotheses. Oryx relative abundances were higher on unencroached grasslands, especially in years of low to moderate precipitation. We found oryx were most active during crepuscular periods, and this behavior was consistent across the shrub encroachment gradient. Our research suggests exotic oryx could contribute to shrub encroachment by focusing their foraging on remaining grasslands, especially during drier years, which may adversely affect livestock production and other ecosystem services.}, keywords = {Diel activity, Habitat use, invasive species, Oryx gazella, shrub encroachment}, doi = {https://doi.org/10.1016/j.jaridenv.2020.104302}, url = {files/bibliography/21-001.pdf}, author = {Andreoni, Kieran and Casey Wagnon and Brandon T Bestelmeyer and Robert L. Schooley} } @article {JRN55206, title = {Evaluation of the automated reference toolset as a method to select reference plots for oil and gas reclamation on Colorado Plateau rangelands}, journal = {Journal of Environmental Management}, volume = {265}, year = {2020}, month = {04/2020}, chapter = {110578}, abstract = {Rangelands are typically characterized by low precipitation and low biomass which makes them susceptible to disturbance and difficult to reclaim. These characteristics become a management issue when considering the widespread and significant impact of oil and gas development on rangelands. Reclamation from this land use involves the complexities of dealing with multiple state and federal agencies, private landowners, and their sometimes conflicting rules. Reference plots (e.g., nearby undisturbed sites) can help with these issues by providing an objective context for reclamation planning. They are selected to provide a comparison that is similar to a reclamation site in most aspects except for the disturbance activity. This allows for the relative condition of the reclamation site to be determined. Because selection of reference plots is normally expert-driven on a site-by-site basis, it can be time consuming and thus ineffective in helping to meet reclamation goals over large landscapes. The Automated Reference Tool (ART) was developed to improve the efficiency and efficacy of reference plot selection. The ART improves reference plot selection through remote sensing and indicators of land potential by selecting reference plots of similar land potential to the reclamation site based on soil texture, topography, and geology. We evaluated the ART in the context of well-pad reclamation to determine if ART selected plots were appropriate to use as reference when compared to an existing reference plot network. We applied the ART to reclamation sites managed by the Bureau of Land Management{\textquoteright}s (BLM) White River Field Office, Colorado which had existing expert-selected reference plots. We found that the ART-selected reference plots and their matching expert-selected reference plot had similar large-scale vegetative cover characteristics (total foliar: R2 {\textonequarter} 0.34, p-value {\textonequarter} 0.0012) and dissimilar finer-scale cover characteristics (plant diversity: R2 {\textonequarter} 0.079, p-value {\textonequarter} 0.15). In addition, we detected similarities in their soil water content (R2 {\textonequarter} 0.43, p-value<0.001), depth to restricting layer (RMSD {\textonequarter} 21.90), and rock fragment (RMSD {\textonequarter} 19.99). These results demonstrate that ART could be a useful tool for managers to help meet their reclamation goals over large landscapes, but it is not a complete automation of the reference selection process.}, keywords = {Land potential, Model verification, monitoring, oil and gas, reclamation, Reference plot selection}, doi = {10.1016/j.jenvman.2020.110578}, url = {files/bibliography/20-012.pdf}, author = {Sean F. Di Stefano and Jason W. Karl and C. Donovan Bailey and Hale, Steven} } @conference {JRN55247, title = {Effects of contrasting rooting distribution patterns on plant transpiration along a precipitation gradient}, booktitle = {Ecological Society of America}, year = {2020}, month = {08/2020}, address = {Virtual Conference}, abstract = {Understanding and predicting ecosystem responses to projected increases in climate extremes in water limited ecosystems requires a thorough assessment of the role plant root systems. Land-use change and shrub encroachment may drastically change root distribution in the soil profile affecting water and nutrient uptake. However, the relationship among plant rooting distribution patterns, climate change and ecosystem functioning has been understudied. Our objective was to study the effect of rooting distribution patterns ranging from very shallow to very deep on plant transpiration across sites along precipitation gradient. We used SOILWAT, a multi-layer, daily time-step model that simulates soil water content by depth in the soil profile. Processes simulated in SOILWAT include water interception and subsequent evaporation from the plant canopy and litter, water infiltration into the soil, vertical water flow among soil layers, evaporation and transpiration from each soil layer, and soil water content by layer. We hypothesized that (1) plant-root distribution has a significant effect on plan transpiration. (2) The effect of rooting depth pattern changes from arid to mesic ecosystems. In order to test these hypotheses, we modeled water losses and soil-water availability at 100 dryland locations with virtual root distributions that simulate shallow and deep root systems. We evaluated the effect of contrasting rooting distribution on maximum plant transpiration, a proxy for plant growth and primary productivity. Our results showed that plant rooting depth has a significant effect on plant transpiration, soil evaporation and deep percolation. The rooting depth profile that maximized plant transpiration changed along a precipitation gradient. Arid ecosystems maximized transpiration with significantly shallower roots than more mesic ecosystems. Differences along the precipitation gradient are related to the relative contribution of water fluxes to the overall water balance. In arid ecosystems, soil water losses occur predominantly through soil evaporation while in mesic ecosystems the main water loss path is deep percolation. Therefore, shallow roots minimized water losses in arid sites (Evap = -1.12 + 8.94 * rooting depth, R2 = 0.3, P = 0.006) and deep roots minimized water losses in mesic sites (Percol = 60.4 {\textendash} 18 * rooting depth, R2 = 0.4, P = 0.008). The effect of biotic exchange and land-use change resulting in novel plant communities with different root traits will affect the water-use efficiency of water limited ecosystems. Changes in rooting distribution patterns will impact primary productivity because plant transpiration is tightly related to photosynthesis. Poster $\#$84160.}, author = {Laureano A. Gherardi and O. E. Sala and Debra C. Peters} } @article {JRN55214, title = {Evaluation of Restoration Success to Inform Future Restoration Efforts in Acacia Reficiens Invaded Rangelands in Northern Kenya}, journal = {Ecological Restoration}, volume = {38}, year = {2020}, month = {06/2020}, pages = {105-113}, abstract = {Arid and semi-arid rangelands support a significant portion of the world{\textquoteright}s human population, as well as its floral and faunal biodiversity. These landscapes are threatened by degradation, through loss of vegetation, increasing spread of invasive and/or undesirable species, or both. Efforts to halt or reverse degradation exist, but lack of monitoring and reporting of restoration outcomes hampers efforts to replicate and upscale good practices to other areas. This paper demonstrates how monitoring can effectively inform future efforts through retrospective analysis of restoration projects on Acacia reficiens invaded rangelands in northern Kenya. A. reficiens has encroached into productive forage land undermining both livestock production systems and endangered wildlife species conservation. We monitored restoration projects across 13 sites involving A. reficiens clearing and seeding with the perennial grass Cenchrus ciliaris using a mobile phone application. We found that these restoration treatments led to increases of more than 25\% in overall cover, 34\% in perennial grass cover, and 60\% in standing herbaceous biomass. We therefore suggest that manual clearing of A. reficiens, when timed properly and combined with both reseeding and prudent pre-and post-treatment seed and soil conservation practices, has the potential to provide an efficient and cost-effective solution to help reverse habitat losses. Our use of mobile phone applications allowed rapid assessment of restoration outcomes, and the resulting data are already being used to help design restoration projects on community-owned rangelands in northern Kenya.}, keywords = {Cenchrus ciliaris, LandPKS, mobile apps, reseeding, tree clearing}, doi = {10.3368/er.38.2.105 }, url = {files/bibliography/20-019.pdf}, author = {D.W. Kimiti and Amy Ganguli and Jeffrey E. Herrick and C. Donovan Bailey} } @conference {JRN55201, title = {Ecosystem service tradeoffs associated with agricultural intensification of grazinglands}, booktitle = {Society for Range Management}, year = {2020}, month = {02/2020}, address = {Denver, CO}, abstract = {The Long-Term Agroecosystem Research (LTAR) network is a team of 18 long-term research sites working to sustainably intensify agricultural production in the croplands, grazinglands, and integrated crop-livestock systems of the United States. The LTAR network seeks not only to increase agricultural production, but also to improve the well-being of agricultural producers and the communities where they live, bolster the profitability of agricultural production, and protect the nation{\textquoteright}s ecosystems and natural resources. The Common Experiment is LTAR{\textquoteright}s central method for investigating how the diverse goals of sustainable intensification could be achieved. Through the Common Experiment, each network site is testing a locally-appropriate {\textquotedblleft}aspirational{\textquotedblright} production system hypothesized to advance sustainable intensification in locally appropriate ways. Sustainable intensification requires action at multiple scales {\textendash} fields, farms, regions, and national and international supply chains - but the common experiment focuses mainly on the scale of the farm or ranch. Recognizing that achieving all goals of sustainable intensification at the same time in the same place is unlikely, the network is investigating the trade-offs of adopting aspirational approaches over {\textquotedblleft}business as usual{\textquotedblright} locally and networkwide. To this end, the LTAR Common Experiment Trade-offs Project team is building a framework to monitor a common set of indicators, so that the 18 sites can track the outcomes of the experimental treatments, and ultimately evaluate the pro{\textquoteright}s and con{\textquoteright}s of adopting the aspirational approaches under investigation nationwide.}, author = {S. Spiegal} } @article {JRN55216, title = {Ecosystem dynamics and aeolian sediment transport in the southern Kalahari}, journal = {African Journal of Ecology}, volume = {58}, year = {2020}, month = {06/2020}, pages = {337-344}, chapter = {337}, abstract = {Aeolian sediment transport processes are sensitive to dryland ecosystem change and can contribute to the transition of savanna grasslands to shrub-invaded and shrub-dominated states. In the southern Kalahari savanna, bush encroachment by Senegalia mellifera is a pervasive ecosystem change that creates mosaic landscapes of varying density grasses and bushes that can affect patterns of aeolian sediment transport. Herbaceous species losses and bush encroachment in the Kalahari have been associated with increased dune mobility, degraded air quality, and potential reactivation of the region as a persistent dust source. While accelerated wind erosion can be both driver and consequence of ecosystem change in the Kalahari, the role of aeolian processes and its regional impacts have not been fully established. Here, we examine preliminary data on the influence of southern Kalahari ecosystem changes on surface aerodynamic roughness and aeolian sediment transport as a basis for understanding their interactions.}, doi = {https://doi.org/10.1111/aje.12700}, url = {files/bibliography/20-026.pdf}, author = {Nicholas Webb and Gregory S. Okin and Abinash Bhattachan and Paolo D{\textquoteright}Odorico and Dintwe, Kebonye and Tatlhego, Mokganedi} } @conference {JRN55175, title = {El rol del bovino Criollo Rar{\'a}muri como herramienta de adaptaci{\'o}n al cambio clim{\'a}tico en los desiertos del SO de los EE.UU.}, year = {2019}, month = {11/5/2019 }, publisher = {XII Simposio Internacional de recursos Geneticos Para Las Americas Y el Caribe}, organization = {XII Simposio Internacional de recursos Geneticos Para Las Americas Y el Caribe}, address = {Rocha, Uruguay}, abstract = {

M{\'u}ltiples modelos clim{\'a}ticos estiman que para mediados del siglo XXI el clima en el sudoeste de los EE.UU. se volver{\'a} m{\'a}s c{\'a}lido (+ 2 a 5 oC), con un r{\'e}gimen de precipitaci{\'o}n m{\'a}s variable (-10 a + 8\%) ocasionando sequias m{\'a}s frecuentes. Se espera que dichos cambios promuevan una ca{\'\i}da en la producci{\'o}n forrajera del pastizal natural, situaciones m{\'a}s frecuentes de estr{\'e}s t{\'e}rmico, y aumento en la incidencia de ectopar{\'a}sitos generando nuevos desaf{\'\i}os para el sector ganadero de la regi{\'o}n. El estado de New Mexico ha visto una ca{\'\i}da significativa en las existencias ganaderas a partir de mediados de la d{\'e}cada del \’70, momento en el que se comenz{\'o} a registrar un incremento significativo en las temperaturas medias anuales. Un an{\'a}lisis reciente de la producci{\'o}n forrajera en un sitio del Desierto de Chihuahua demostr{\'o} una reducci{\'o}n de aproximadamente un 40\% en con respecto a valores de la d{\'e}cada del \’70. Se piensa, por lo tanto, que la sustentabilidad de los sistemas de cr{\'\i}a bovina de la regi{\'o}n depender{\'a} en parte del uso de recursos gen{\'e}ticos ganaderos que exhiban alto grado de adaptaci{\'o}n a las condiciones ambientales emergentes. Desde hace aproximadamente 10 a{\~n}os se estudia la factibilidad de utilizar el bovino Criollo Rar{\'a}muri, uno de 33 biotipos de ganado Criollo de las Am{\'e}ricas, criado a lo largo de 4 siglos en condiciones aisladas en las Sierras de Tarahumara por pueblos originarios del mismo nombre. En condiciones de pastoreo extensivo, vacas de este biotipo han demostrado patrones del uso del h{\'a}bitat y de tolerancia al calor superiores a los del ganado europeo o {\'\i}ndico com{\'u}nmente utilizado en la regi{\'o}n. An{\'a}lisis preliminares de ganancia de peso y calidad de carne sugieren que el bovino Criollo Rar{\'a}muri o sus cruzamientos podr{\'\i}an ser una herramienta para la producci{\'o}n sustentable de carne en la regi{\'o}n.

English translation:

Multiple climate models estimate that by the middle of the 21st century the climate in the south-west of the U.S. will become warmer (+ 2 to 5 oC), with a more variable precipitation regime (-10 to +8\%) causing more frequent droughts. These changes are expected to promote a drop in natural grassland forage production, more frequent situations of thermal stress, and increased incidence of ectoparasites creating new challenges for the region\&$\#$39;s livestock sector. The state of New Mexico has seen a significant drop in livestock stocks since the mid-1970s, at which point there began to be a significant increase in average annual temperatures. A recent analysis of forage production at a site in the Chihuahua Desert showed a reduction of approximately 40\% compared to values of the 1970s. It is therefore thought that the sustainability of bovine breeding systems in the region will depend in part on the use of livestock genetic resources that exhibit a high degree of adaptation to emerging environmental conditions. For approximately 10 years it has been studied the feasibility of using the cattle Criollo Rar{\'a}muri, one of 33 biotypes of Criollo cattle of the Americas, bred over 4 centuries under isolated conditions in the Sierras de Tarahumara by native peoples of the same name. Under extensive grazing conditions, cows of this biotype have demonstrated patterns of habitat use and heat tolerance higher than those of European or Indian livestock commonly used in the region. Preliminary analysis of weight gain and meat quality suggests that Criollo Rar{\'a}muri cattle or their crossings could be a tool for sustainable meat production in the region.

}, author = {Andr{\'e}s F. Cibils and Richard E. Estell and Amy L. Gonzalez and S. Spiegal and S. Nyamuryekung{\textquoteright}e and Matthew M. McIntosh} } @conference {JRN55236, title = {The effects of climate change on agricultural systems: A Southwest climate Hub curriculum unit for 6th-12th grade students}, booktitle = {American Geophysical Union}, year = {2019}, month = {10/2019}, address = {San Francisco, California}, abstract = {Assessing vulnerability of agricultural systems to climate variability and change is vital in securing food systems and sustaining rural livelihoods. Farmers, ranchers, and forest landowners rely on science-based, decision-relevant, and localized information to maintain production, ecological viability, and economic returns. This contribution synthesizes a collection of research on the future of agricultural production in the American Southwest (SW). Research was based on a variety of geospatial methodologies and datasets to assess the vulnerability of rangelands and livestock, field crops, specialty crops, and forests in the SW to climate-risk and change. This collection emerged from the development of regional vulnerability assessments for agricultural climate-risk by the U.S. Department of Agriculture (USDA) Climate Hub Network, established to deliver science-based information and technologies to enable climate-informed decision-making. Authors defined vulnerability differently based on their agricultural system of interest, although each primarily focuses on biophysical systems. We found that an inconsistent framework for vulnerability and climate risk was necessary to adequately capture the diversity, variability, and heterogeneity of SW landscapes, peoples, and agriculture. ~Through the diversity of research questions and methodologies, this collection of articles provides valuable information on various aspects of SW vulnerability. All articles relied on geographic information systems technology, with highly variable levels of complexity. Agricultural articles used National Agricultural Statistics Service data, either as tabular county level summaries or through the CropScape cropland raster datasets. Most relied on modeled historic and future climate information, but with differing assumptions regarding spatial resolution and temporal framework. We assert that it is essential to evaluate climate risk using a variety of complementary methodologies and perspectives. In addition, we found that spatial analysis supports informed adaptation, within and outside the SW United States. The persistence and adaptive capacity of agriculture in the water-limited Southwest serves as an instructive example and may offer solutions to reduce future climate risk. Paper number $\#$ED33A-0935.}, author = {Emile H. Elias and J.T. Reyes and Caitriana Steele and Stephanie Bestelmeyer and Stephanie Haan-Amato} } @conference {JRN55235, title = {The evolution of partnerships and their role in building resilience in the first five years of the USDA Climate Hub Network}, booktitle = {American Geophysical Union}, year = {2019}, month = {10/2019}, address = {San Francisco, California}, abstract = {In February 2014, former Secretary of Agriculture Tom Vilsack announced the formation of 10 Climate Hubs across the United States to {\textquotedblleft}Develop and deliver science-based, region-specific information and technologies to agricultural and natural resource managers, and communities that enable climate-smart decision-making.{\textquotedblright} Here we present examples of the emergence and evolution of partnerships from the USDA Southwest Climate Hub (SWCH) through the lens of building resilience in the agricultural and forestry community sectors. All examples have distinctly different provenance (from opportunistic to strategic), time-horizons (weeks to years) and efficacy in building resilience, defined as a community-based positive sense of persisting during adversity. The partnerships stem from a strategic vision, a data need and a weather event (exceptional drought). 1). Early on the SWCH engaged with regional land grant Universities by awarding small grants to Cooperative Extension. This partnership has supported engagement with stakeholders in far-off locations (Hawaii and the U.S. affiliated Pacific Islands) and creative, necessary ongoing projects (MyRainge in Arizona). A series of meetings led to the Extension Climate Network. 2). The Colorado Plateau exceptional drought of 2018 led to rapid development and delivery of webinars for stakeholders and media designed to share information about current and projected weather conditions and likely impacts. The webinars were presented by regional and national experts to stakeholders. Many partners contributed to these including the SWCH, the National Integrated Drought Information System, the National Drought Mitigation Center, State Climatologists and others. These webinars gained considerable media attention and positive feedback, especially after fires emerged in Southwestern Colorado, but may have had limited benefit in terms of long-term resilience. 3). A data need to support Grass-Cast, a rangeland productivity tool, led to a collaboration between the Bureau of Indian Affairs, Navajo Nation, a consulting firm and Hubs to collect and make available data to support future Grass-Cast projections. We describe our experience of the efficacy of these collaborative partnerships in building resilience and future best-practices. Paper number $\#$PA43E-1184.}, author = {Emile H. Elias and J.T. Reyes and Caitriana Steele and Helena Deswood} } @article {JRN55145, title = {Extreme weather events and transmission losses in arid streams}, journal = {Environmental Research Letters}, volume = {14}, year = {2019}, pages = {084002}, abstract = {

A limited understanding of how extreme weather events affect groundwater hinders our ability to predict climate change impacts in drylands, where channel transmission losses are often the primary recharge mechanism. In this study, we investigate how potential changes to precipitation intensity and temperature will affect the water balance of a typical first-order, arid watershed located in the Chihuahuan Desert. We utilize a process-based hydrologic model driven by stochastically-downscaled simulations from a set of climate models, emissions scenarios, and future periods. Across many simulations, the average daily storm size is the primary factor that controls transmission losses with larger precipitation amounts increasing channel infiltration while simultaneously decreasing land surface evapotranspiration. Extreme events (\>25 mm d-1) that account for less than 30\% of the annual precipitation, contribute almost 50\% of the focused recharge. As a result, climatic changes leading to larger, less frequent storms will result in higher channel transmission losses in arid regions.

}, keywords = {channel transmission losses, climate change, distributed hydrologic modeling, dryland ecohydrology, extreme events, groundwater recharge, hydrology, hydrology model, water balance}, doi = {10.1088/1748-9326/ab2949}, url = {files/bibliography/19-019_0.pdf}, author = {A. P. Schreiner-McGraw and Ajami, Hoori and Enrique Vivoni} } @conference {JRN54934, title = {Evaluation of the automated reference toolset for oil and gas reclamation on Colorado rangelands}, booktitle = {Society for Range Management Meeting Proceedings}, year = {2018}, month = {01/2018}, address = {Sparks, Nevada }, abstract = {

Rangelands are characterized by low precipitation and low biomass, making them susceptible to disturbance and difficult to reclaim. Considering the widespread and significant impact of oil and gas development on rangelands, effective reclamation is vital. Thus, it is important that land managers understand the ecological context of a reclamation site so that management outcomes can be correctly interpreted. This is often accomplished through comparison of reclamation areas to reference sites which are selected by their similarity to the reclamation area{\textquoteright}s pre-disturbance condition, so that the relative condition of a reclamation site can be determined. Reference site selection is normally expert driven on a site-by-site basis, and thus can be inconsistently applied and ineffective in helping to meet reclamation goals over large landscapes. The Automated Reference Tool (ART) was developed to improve the efficiency and efficacy of reference site selection by selecting reference sites of similar land potential to the reclamation area based on soil texture, topography, and geology. However, ART has not been previously evaluated in a management context. Our objectives were to evaluate ART within this context and determine if existing reference sites are appropriate reference sites for well-pads. We applied the ART to oil \& gas reclamation sites managed by the Bureau of Land Management{\textquoteright}s (BLM) White River Field Office, Colorado, to their reference sites and to nearby sites from the BLM{\textquoteright}s Assessment, Inventory, and Monitoring (AIM) program. Both existing reference sites and nearby AIM sites varied in their similarity to reclamation sites according to ART and in terms of vegetation composition from field sampling. Based on these results, ART can complement expert-driven reference site selection, making reference site selection quicker, more quantitative, and defensible, helping land managers better meet their reclamation needs.

}, author = {Sean F. Di Stefano and Colby Brungard and Jason W. Karl and Nelson Stauffer and Sarah McCord} } @proceedings {JRN54857, title = {Evaluation of the automated reference toolset for oil and gas reclamation on Colorado rangelands}, volume = {January 28-February 2, 2018}, year = {2018}, month = {01/28/2018}, publisher = {Society for Range Management Meeting Procedings}, address = {Reno, NV}, abstract = {

Rangelands are characterized by low precipitation and low biomass, making them susceptible to disturbance and difficult to reclaim. Considering the widespread and significant impact of oil and gas development on rangelands, effective reclamation is vital. Thus, it is important that land managers understand the ecological context of a reclamation site so that management outcomes can be correctly interpreted. This is often accomplished through comparison of reclamation areas to reference sites which are selected by their similarity to the reclamation area{\textquoteright}s pre-disturbance condition, so that the relative condition of a reclamation site can be determined. Reference site selection is normally expert driven on a site-by-site basis, and thus can be inconsistently applied and ineffective in helping to meet reclamation goals over large landscapes. The Automated Reference Tool (ART) was developed to improve the efficiency and efficacy of reference site selection by selecting reference sites of similar land potential to the reclamation area based on soil texture, topography, and geology. However, ART has not been previously evaluated in a management context. Our objectives were to evaluate ART within this context and determine if existing reference sites are appropriate reference sites for well-pads. We applied the ART to oil \& gas reclamation sites managed by the Bureau of Land Management{\textquoteright}s (BLM) White River Field Office, Colorado, to their reference sites and to nearby sites from the BLM{\textquoteright}s Assessment, Inventory, and Monitoring (AIM) program. Both existing reference sites and nearby AIM sites varied in their similarity to reclamation sites according to ART and in terms of vegetation composition from field sampling. Based on these results, ART can complement expert-driven reference site selection, making reference site selection quicker, more quantitative, and defensible, helping land managers better meet their reclamation needs.

}, author = {Sean F. Di Stefano and Colby Brungard and Jason W. Karl and Nelson Stauffer and Jonathan Maynard} } @proceedings {JRN54864, title = {Elevated dust emissions on the Colorado Plateau: Role of grazing vehicle disturbance, and increasing aridity}, volume = {January 28-February 2, 2018}, year = {2018}, month = {01/28/2018}, publisher = {Society for Range Management Meeting Proceedings}, address = {Sparks, Nevada}, abstract = {

Dust from drylands are of major concern to human society. Dust deposition onto snowpacks can hasten melt rates, resulting in lowered inputs into major rivers. Blowing dust can result in traffic accidents, respiratory disease, and high economic costs. To abate dust emissions, it is necessary to examine suspected sources such as unpaved roads and grazing lands. We measured aeolian sediment mass fluxes in low elevation rangelands and unsurfaced roads on the Colorado Plateau in Utah, USA. Empirical spatial modeling suggests that rangelands are producing ~92-93\% of regional dust and roads ~7-8\%. Measured {\textquoteleft}hot spots{\textquoteright} in sediment mass flux at 100 cm height rival the highest ever recorded including 7,460 gm-2day-1 (spring 2009) in an off-highway vehicle (OHV) area near Hanksville, UT, but were more commonly 50-2,000 gm-2day-1 \ in areas with heavy grazing or OHV use. \ The overall mean measured rangeland sediment mass flux at 100 cm height was 5.14 gm-2day-1, considerably lower than grazed areas (~8-20 gm-2day-1) and OHV areas (414 gm-2day-1). In contrast, a similar area monitored with minimal soil disturbance averaged 1.60 gm-2day-1 from 2007-2015. Annual sediment mass fluxes on all rangeland land use types (light/not grazed, moderately and heavily grazed, and OHV) generally increased with increasing annual temperature, increased winds, and decreasing precipitation. Mass fluxes measured just downwind of unpaved road sites averaged 13.14 gm-2day-1 with a maximum observed seasonal flux of 128.0 gm-2day-1 along a producing oil well access road. Four of the five highest road flux values (n=33 total) measured were adjacent to roads primarily used to access oil or gas well-pads, while one was a road servicing both recreation and well-pads. These findings suggest that predicted future regional mega-droughts may increase dust emissions already elevated due to land management, potentially further compromising air quality, hydrologic cycles, and other ecological services linked to dust.

}, author = {Travis Nauman and Danielle Duni and Nicholas Webb and Jayne Belnap} } @article {JRN54887, title = {Evaluating strategies for sustainable intensification of U.S. agriculture through the Long-Term Agroecosystem Research network}, journal = {Environmental Research Letters}, volume = {13(3):034031}, year = {2018}, month = {03/2018}, abstract = {

Sustainable intensification is an emerging model for agriculture designed to reconcile accelerating global demand for agricultural products with long-term environmental stewardship. Defined here as increasing agricultural production while maintaining or improving environmental quality, sustainable intensification hinges upon decision-making by agricultural producers, consumers, and policy-makers. The Long-Term Agroecosystem Research (LTAR) network was established to inform these decisions. Here we introduce the LTAR Common Experiment, through which scientists and partnering producers in US croplands, rangelands, and pasturelands are conducting 21 independent but coordinated experiments. Each local effort compares the outcomes of a predominant, conventional production system in the region ({\textquoteright}business as usual{\textquoteright}) with a system hypothesized to advance sustainable intensification ({\textquoteright}aspirational{\textquoteright}). Following the logic of a conceptual model of interactions between agriculture, economics, society, and the environment, we identified commonalities among the 21 experiments in terms of (a) concerns about business-as-usual production, (b) {\textquoteright}aspirational outcomes{\textquoteright} motivating research into alternatives, (c) strategies for achieving the outcomes, (d) practices that support the strategies, and (e) relationships between practice outreach and adoption. Network-wide, concerns about business as usual include the costs of inputs, opportunities lost to uniform management approaches, and vulnerability to accelerating environmental changes. Motivated by environmental, economic, and societal outcomes, scientists and partnering producers are investigating 15 practices in aspirational treatments to sustainably intensify agriculture, from crop diversification to ecological restoration. Collectively, the aspirational treatments reveal four general strategies for sustainable intensification: (1) reducing reliance on inputs through ecological intensification, (2) diversifying management to match land and economic potential, (3) building adaptive capacity to accelerating environmental changes, and (4) managing agricultural landscapes for multiple ecosystem services. Key to understanding the potential of these practices and strategies are informational, economic, and social factors{\textemdash}and trade-offs among them{\textemdash}that limit their adoption. LTAR is evaluating several actions for overcoming these barriers, including finding financial mechanisms to make aspirational production systems more profitable, resolving uncertainties about trade-offs, and building collaborative capacity among agricultural producers, stakeholders, and scientists from a broad range of disciplines.

}, keywords = {agroecosystem management, long-term research network, social-ecological systems, sustainable intensification of agriculture}, doi = {10.1088/1748-9326/aaa779}, url = {files/bibliography/18-003.pdf}, author = {S. Spiegal and Brandon T Bestelmeyer and D W Archer and D.J. Augustine and Elizabeth H. Boughton and Raoul K. Boughton and Patrick E. Clark and J. D. Derner and Emily Duncan and Michael Cavigelli and Hapeman, Cathleen and Harmel, Robert D. and Phil Heilman and Holly, Michael A. and David Huggins and K.W. King and Peter J. A. Kleinman and M. A. Liebig and Martin Locke and Gregory McCarty and Millar, Neville and Steven Mirsky and Thomas Moorman and Frederick B. Pierson and James Rigby JR and Robertson, G. Phillip and Jean Steiner and Timothy Strickland and Hilary Swain and Brian Wienhold and J. D. Wulfhorst and Yost, Matthew and C. Walthall} } @article {JRN54917, title = {Effect of climeodaphic heterogeneity on woody plant dominance in the Argentine Caldenal region}, journal = {Rangeland Ecology and Management}, volume = {71:409-416}, year = {2018}, month = {06/2018}, abstract = {

Woody plant encroachment is widespread throughout drylands of the world, but rates and patterns of encroachment at the regional scale can be mediated by soil and climate. Climoedaphic properties may therefore help to explain patterns of woody plant dominance. In the Caldenal region of central Argentina, which is experiencing widespread woody plant encroachment, we used stratified and targeted inventory of vegetation and soils alongside climate data to classify ecological states and then identify factors suggesting resistance to woody plant encroachment. We found that three climoedaphic contexts differ in the degree of woody plant dominance. Sandsheet landforms had the lowest likelihood of a woody plant thicket state. Within loamy soils, sites with deep soil carbonates in warmer and wetter climates were less likely to feature a shrub thicket state than sites with shallow carbonates in cooler and drier climates. These contexts serve as a basis for recognizing different ecological sites to assist mapping and prioritization of management interventions in the Caldenal region. Simple inventory-based approaches can be helpful for designing land management recommendations in other ecosystems.

}, doi = {10.1016/j.rama.2018.03.001}, url = {files/bibliography/18-011.pdf}, author = {L.N. Svejcar and H. Raul Peinetti and Brandon T Bestelmeyer} } @article {JRN54783, title = {Exploring ecological careers {\textendash} A new Frontiers series}, journal = {Frontiers in Ecology and the Environment}, volume = {15}, year = {2017}, pages = {336-337}, abstract = {

This article provides an the introduction to a series describing non-academic careers in ecology. The world offers many niches for ecologists and the \ myriad and complex environmental challenges facing us continue to create new career opportunities. Historically, graduate students have interacted closely with ecologists who, at some level, often believe that the choice they made to pursue a career in academia is the one that would also be best for their students. However, while demand for ecologists outside of academia is increasing, the number of academic positions available is far below the number of individuals interested in these positions. The series, for which this article provides an introduction, will explore in depth, and from a number of different perspectives, opportunities for developing pathway wide variety exciting careers in ecology . Our ultimate focus will be to highlight the relevant knowledge, experience and skills that can help to align students{\textquoteright} career goals with emerging career opportunities.

}, doi = {doi:10.1002/fee.1508}, url = {files/bibliography/17-015.pdf}, author = {Klemow, Kenneth and Bowser, Gillian and Cid, Carmen and Middendorf, George and Mourad, Teresa and Jeffrey E. Herrick} } @conference {JRN54932, title = {Emerging ecological datasets with application for modeling North American dust emissions}, booktitle = {American Geophysical Union}, year = {2017}, month = {12/2017}, address = {New Orleans, Louisiana}, abstract = {

In 2011 the US Bureau of Land Management (BLM) established the Assessment, Inventory and Monitoring (AIM) program to monitor the condition of BLM land and to provide data to support evidence-based management of multi-use public lands. The monitoring program shares core data collection methods with the Natural Resources Conservation Service{\textquoteright}s (NRCS) National Resources Inventory (NRI), implemented on private lands nationally. Combined, the two programs have sampled \>30,000 locations since 2003 to provide vegetation composition, vegetation canopy height, the size distribution of inter-canopy gaps, soil texture and crusting information on rangelands and pasture lands across North America. The BLM implements AIM on more than 247.3 million acres of land across the western US, encompassing major dust source regions of the Chihuahuan, Sonoran, Mojave and Great Basin deserts, the Colorado Plateau, and potential high-latitude dust sources in Alaska. The AIM data are publicly available and can be used to support modeling of land surface and boundary-layer processes, including dust emission. While understanding US dust source regions and emission processes has been of national interest since the 1930s Dust Bowl, most attention has been directed to the croplands of the Great Plains and emission hot spots like Owens Lake, California. The magnitude, spatial extent and temporal dynamics of dust emissions from western dust source areas remain highly uncertain. Here, we use ensemble modeling with empirical and physically-based dust emission schemes applied to AIM monitoring data to assess regional-scale patterns of aeolian sediment mass fluxes and dust emissions. The analysis enables connections to be made between dust emission rates at source and other indicators of ecosystem function at the landscape scale. Emerging ecological datasets like AIM provide new opportunities to evaluate aeolian sediment transport responses to land surface conditions, potential interactions with disturbances (e.g., fire) and ecological change (e.g., invasive species), and the impacts of anthropogenic land use and land cover change.

}, author = {Sarah McCord and Nelson Stauffer and S. L. Garman and Nicholas Webb} } @article {JRN54791, title = {Evaluating MODIS snow products for modelling snowmelt runoff: case study of the Rio Grande headwaters}, journal = {International Journal of Applied Earth Observation and Geoinformation}, volume = {63}, year = {2017}, month = {09/2017}, pages = {234-243}, chapter = {234}, abstract = {

Snow-covered area (SCA) is a key variable in the Snowmelt-Runoff Model (SRM) and in other models for simulating discharge from snowmelt. Landsat Thematic Mapper (TM), Enhanced Thematic Mapper (ETM +) or Operational Land Imager (OLI) provide remotely sensed data at an appropriate spatial resolution for mapping SCA in small headwater basins, but the temporal resolution of the data is low and may not always provide sufficient cloud-free dates. The coarser spatial resolution Moderate Resolution Imaging Spectroradiometer (MODIS) offers better temporal resolution and in cloudy years, MODIS data offer the best alternative for mapping snow cover when finer spatial resolution data are unavailable. However, MODIS{\textquoteright} coarse spatial resolution (500 m) can obscure fine spatial patterning in snow cover and some MODIS products are not sensitive to end-of-season snow cover. In this study, we aimed to test MODIS snow products for use in simulating snowmelt runoff from smaller headwater basins by a) comparing maps of TM and MODIS-based SCA and b) determining how SRM streamflow simulations are changed by the different estimates of seasonal snow depletion. We compared gridded MODIS snow products (Collection 5 MOD10A1 fractional and binary SCA; SCA derived from Collection 6 MOD10A1 Normalised Difference Snow Index (NDSI) Snow Cover), and the MODIS Snow Covered- Area and Grain size retrieval (MODSCAG) canopy-corrected fractional SCA (SCAMG), with reference SCA maps (SCAREF) generated from binary classification of TM imagery. SCAMG showed strong agreement with SCAREF; excluding true negatives (where both methods agreed no snow was present) the median percent difference between SCAREF and SCAMG ranged between -2.4\% and 4.7\%. We simulated runoff for each of the four study years using SRM populated with and calibrated for snow depletion curves derived from SCAREF. We then substituted in each of the MODIS-derived depletion curves. With efficiency coefficients ranging between 0.73 and 0.93, SRM simulation results from the SCAMG runs yielded the best results of all the MODIS products and only slightly underestimated discharge volume (between 7 and 11\% of measured annual discharge). SRM simulations that used SCA derived from Collection 6 NDSI Snow Cover also yielded promising results, with efficiency coefficients ranging between 0.73 and 0.91. In conclusion, we recommend that when simulating snowmelt runoff from small basins (\< 4000 km2) with SRM, we recommend that users select either canopy-corrected MODSCAG or create their own site-specific products from the Collection 6 MOD10A1 NDSI.

}, keywords = {MOD10A1, MODIS snow products, MODSCAG, snow covered area, Snowment Runoff Model}, doi = {dx.doi.org/10.1016/j.jag.2017.08.007}, url = {files/bibliography/17-018.pdf}, author = {Caitriana Steele and Jake Dialesandro and D. K. James and Emile H. Elias and A. Rango and M. Bleiweiss} } @article {JRN54794, title = {Enhancing wind erosion monitoring and assessment for US rangelands}, journal = {Rangelands}, volume = {39}, year = {2017}, month = {09/2017}, pages = {85-96}, chapter = {85}, abstract = {

Wind erosion is a major resource concern for rangeland managers because it can impact soil health, ecosystem structure and function, hydrologic processes, agricultural production and air quality. \ Despite its significance, little is known about which landscapes are eroding, by how much, and when. \ The National Wind Erosion Research Network was established in 2014 to develop tools for monitoring and assessing wind erosion and dust emission across the U.S. The Network, currently consisting of 13 sites, creates opportunities to enhance existing rangeland soil, vegetation and air quality monitoring programs. \ Decision-support tools developed by the Network will improve the prediction and management of wind erosion across rangeland ecosystems.

}, doi = {10.1016/j.rala.2017.04.001}, url = {files/bibliography/17-016.pdf}, author = {Nicholas Webb and Justin Van Zee and Jason W. Karl and Jeffrey E. Herrick and Ericha Courtright and Billings, Benjamin and Boyd, Robert and A. Chappell and Danielle Duni and J. D. Derner and Hand, Jenny and Emily Kachergis and Sarah McCord and Beth Newingham and Frederick B. Pierson and Jean Steiner and John Tatarko and Negussie Tedela and David P. Toledo and Scott Van Pelt} } @book {JRN55181, title = {Exploring a Desert Experiences of an Ecologist/Naturalist in a New Mexico Desert}, year = {2017}, pages = {189}, abstract = {

The book focuses on the ecology of the northern Chihuahuan Desert with chapters on geomorphology, landscapes, climate, vegetation,(special chapters on Creosotebush and Mesquite) mammals, reptiles, ephemeral aquatic systems, ants, termites, insects on plants, ground dwelling arthropods, and soil fauna. Descriptions of studies and field experiments are provided to show how the information was obtained.

}, keywords = {ants, climate, creosotebush, ecology, ephemeral aquatic systems, geomorphology, ground dwelling arthropods, insects on plants, landscapes, mammals, mesquite, northern Chihuahuan Desert, reptiles, soil fauna., termites, vegetation}, url = {files/bibliography/17-Whitford_Exploring-a-Desert.pdf}, author = {Walter G. Whitford} } @article {JRN54583, title = {Effects of exurban development on trophic interactions in a desert landscape}, year = {2016}, abstract = {

Context. Mechanisms of ecosystem change in urbanizing landscapes are poorly understood, especially in exurban areas featuring residential or commercial development set in a matrix of modified and natural vegetation. We asked how development altered trophic interactions and ecosystem processes in the matrix.
Objectives. We examined the effect of varying degrees of exurban development (housing density) on a trophic system that included an apex mammalian predator (coyote, Canis latrans), mammalian herbivores (lagomorphs and rodents), and herbaceous plants. We tested the hypothesis that plant recruitment would be negatively affected by exurban development due either to increases in herbivores associated with increased resource availability (a bottom{\textendash}up effect) or to a reduction in predators that avoid humans (a top{\textendash} down effect).
Methods. In Las Cruces, New Mexico, USA, four replicate sites were located in each of three urbanization levels: high density exurban, low density exurban, and wildland dominated by Chihuahuan Desert vegetation. Seedling trays measured herbivory rates, live trapping estimated abundance of pocket mice and kangaroo rats, and remotely-triggered wildlife cameras estimated the activity of lagomorphs and coyotes.
Results. Increased herbivory on seedlings and decreased herbaceous plant recruitment were observed in high density exurban areas. Overall rodent abundance, seed consumption rates, and activity of the lagomorph Lepus californicus did not vary with urbanization level. Activity by another lagomorph, Sylvilagus audubonii, and coyotes was highest in dense exurban areas, consistent with a bottom{\textendash}up effect.
Conclusions. Exurban development can have important indirect effects on trophic interactions occurring in adjacent, untransformed ecosystems. Similar to earlier studies, such effects in the Chihuahuan Desert may be mediated by bottom{\textendash}up processes associated with anthropogenic inputs.

}, keywords = {Chihuahuan Desert, coyote, lagomorph, plant recruitment, rodent, urbanization}, doi = {10.1007/s10980-016-0403-9}, url = {/files/bibliography/16-025.pdf}, author = {Kristen Davanon and Lindsey Howard and Karen Mabry and Robert L. Schooley and Brandon T Bestelmeyer} } @conference {JRN54611, title = {Ensuring coordination and collaboration across climate science entities: toward effective stakeholder engagement for science-informed decisions}, booktitle = {American Geophysical Union}, year = {2016}, month = {12/2016}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {
As one of the newest federal programs to emerge in response to climate change, the U.S. Department of Agriculture (USDA) Climate Hubs were established to assist farmers, ranchers and forest landowners in their adaptation and mitigation efforts under a changing climate. The Hubs{\textquoteright} mission is to deliver science-based information and tools to agricultural and natural resource land managers, to enable climate-informed decision-making. By facilitating and transferring tools and knowledge, the Hubs also provide value to cooperative extension, land grant institutions, and USDA itself, especially in leveraging existing resource capacity. Various federal agencies (NOAA, USGS, USFWS) have also developed climate change coordination networks: \ RISAs, CSCs, and LCCs. These regionally-based federal networks can best operate in collaboration with one another. At their programmatic level, however, there are fundamental discrepancies in mission, stakeholder definition and geographic region. In this presentation, we seek to compare and contrast these divergent characteristics by identifying {\textquoteleft}hot spots{\textquoteright} and {\textquoteleft}hot moments{\textquoteright} where definitions, programs, or priorities may intersect due to place-based or event-based issues. The Southwest (SW) region of the United States, which presently operates under warm and dry conditions, is projected to become warmer and drier in the future. On-going drought conditions have presented an opportunity to maintain and build professional networks among these federal climate change coordination networks, as well as within USDA, to better understand impacts and respond to stakeholder needs. Projects in the Rio Grande River Valley and with Tribal nations highlight successful collaboration based on geography and common stakeholders, respectively. Aridity and water scarcity characterize the SW region and provide an overarching theme to better support adaptation and mitigation, as well as create opportunities for collaborative success.\ 
}, author = {Emile H. Elias and Caitriana Steele and A. Rango and J.T. Reyes and Langston, Mike and Johnson, Kevin and Rice, John} } @article {JRN54522, title = {Effect of light intensity and wavelength on concentration of plant secondary metabolites in the leaves of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {65}, year = {2016}, month = {04/2016}, pages = {108-114}, chapter = {108}, abstract = {

Flourensia cernua (tarbush) is a shrub that has encroached into grasslands in many areas of the northern Chihuahuan Desert and contains high levels of carbon-based secondary compounds. Concentrations of secondary compounds are affected by numerous biotic and abiotic influences, including amount and wavelength of solar radiation. However, responses to shade and ultraviolet light restriction are inconsistent among plant species and compound class. We conducted a three-year study to evaluate the effect of shade and UV light restriction on total phenolic and terpene concentrations in tarbush. Sixty plants were randomly assigned to one of three treatments (control, UV light restriction, or 50\% incident light restriction). Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Total phenolics did not differ between UV-restricted and control plants, but were lower in shaded plants than the other treatments (P \< 0.05).\  Total volatiles tended to be greater for the UV-restricted treatment than control plants (P= 0.056), with shaded plants not different from either treatment. Treatment effects were detected for 18 individual compounds (P \< 0.05). Our results partially support the hypothesis that UV restriction and shading alter carbon-based secondary chemical concentrations.

}, keywords = {Flourensia cernua, phenolics, plant secondary metabolites, shade, terpenes, ultraviolet light}, doi = {10.1016/j.bse.2016.02.019}, url = {/files/bibliography/16-006.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James} } @conference {JRN54648, title = {Effects of contrasting rooting distribution patterns on plant transpiration along a precipitation gradient}, booktitle = {Ecological Society of America}, year = {2016}, month = {08/2016}, publisher = {Ecological Society of America Abstracts}, organization = {Ecological Society of America Abstracts}, address = {Ft Lauderdale, FL}, abstract = {

Understanding and predicting ecosystem functioning in water limited ecosystems requires a thorough assessment of the role plant root systems. Widespread ecological phenomena such as shrub encroachment may drastically change root distribution in the soil profile affecting the uptake of water and nutrients. However, the relationship between plant rooting distribution patterns and ecosystem functioning has been largely overlooked. Our objective was to assess the role of a range of rooting distribution patterns on plant transpiration across sites along precipitation gradient. We used SOILWAT, a multi-layer, daily time-step model that simulates soil water content by depth in the soil profile. Processes simulated in SOILWAT include water interception and subsequent evaporation from the plant canopy and litter, water infiltration into the soil, vertical water flow among soil layers, evaporation and transpiration from each soil layer, and soil water content by layer. We hypothesized that (1) plant root distribution would have a significant effect on plan transpiration. (2) The effect of rooting pattern changes along a precipitation gradient. In order to test these hypotheses, we modeled water losses and soil-water availability at 55 grassland locations with virtual root distributions that simulate shallow and deep root systems. We evaluated the effect of contrasting rooting distribution on plant transpiration, a variable tightly correlated with plant growth and primary productivity. Our results show that plan rooting distribution patterns have a significant effect on plant transpiration. Shallow root distribution showed significantly lower transpiration than deep root distributions, a mean difference of 8.2 cm/yr. Such effect changed along a precipitation gradient showing smaller effects of root distribution in arid sites than in mesic sites. Locally, plant transpiration increased with rooting depth up to a point where transpiration reached a plateau. The shape of such relationship and the maximum transpiration rate changed among sites. Arid ecosystems showed shallower transpiration rate increases as root depth increased and smaller maximum transpiration rates than mesic ecosystems. The effect of species invasions or changes in the relative abundance of plan types with different root traits will affect ecosystem functioning. Given the tight relationship that exists between transpiration and photosynthesis, we expect that changes in rooting distribution patterns will impact primary productivity with greater effects in mesic.

}, author = {Laureano A. Gherardi and O. E. Sala and Debra C. Peters} } @article {JRN54599, title = {Effect of spatial image support in detecting long-term vegetation change from satellite time-series}, journal = {Landscape Ecology}, year = {2016}, month = {05/2016}, pages = {2045-2062}, type = {Peer Reviewed}, chapter = {2045}, abstract = {Context: Arid rangelands have been severely degraded over the past century. Multi-temporal remote sensing techniques are ideally suited to detect significant changes in ecosystem state; however, considerable uncertainty exists regarding the effects of changing image resolution on their ability to detect ecologically meaningful change from satellite time-series. Objectives: (1) Assess the effects of image resolution in detecting landscape spatial heterogeneity. (2) Compare and evaluate the efficacy of coarse (MODIS) and moderate (Landsat) resolution satellite time-series for detecting ecosystem change. Methods: Using long-term vegetation monitoring data from grassland and scrubland sites in southern New Mexico, USA, we evaluated the effects of changing image support using MODIS (250-m) and Landsat (30-m) time-series in modeling and detecting significant changes in vegetative biomass using time-series decomposition techniques. Results: Within our study ecosystem, landscape-scale (>20-m) spatial heterogeneity was low, resulting in a similar ability to detect vegetation changes across both satellite sensors and levels of spatial image support. While both Landsat and MODIS imagery were effective in modeling temporal dynamics in vegetation structure and composition, MODIS was more strongly correlated to biomass due to its cleaner (i.e., fewer artifacts/data gaps) 16-day temporal signal. Conclusions: The optimization of spatial/temporal scale is critical in ensuring adequate detection of change. While the results presented in this study are likely specific to arid shrub-grassland ecosystems, the approach presented here is generally applicable. Future analysis is needed in other ecosystems to assess how scaling relationships will change under different vegetation communities that range in their degree of landscape heterogeneity. }, doi = {10.1007/s10980-016-0381}, url = {/files/bibliography/16-026.pdf}, author = {Jonathan Maynard and Jason W. Karl and Dawn M. Browning} } @article {JRN54146, title = {Emerging technological and cultural shifts advancing drylands research and management}, journal = {Frontiers in Ecology and the Environment}, volume = {13}, year = {2015}, month = {02/2015}, pages = {52-60}, chapter = {52}, abstract = {

Sustainable management of arid landscapes is complicated by extreme conditions that constrain biological responses to perturbation, great spatial complexity, and uncertain degrees of ecosystem resilience to climate change. Traditional approaches to the collection, management, and analysis of data from dryland monitoring efforts should consider these complications. Over the past century, research on drylands has gradually transitioned from short-term, plot-scale studies to long-term, regional- and biome-scale efforts. Two thresholds are imminent: a technological tipping point that will facilitate performing novel science using new techniques to collect, manage, and analyze data, and a cultural tipping point, where various research products are shared more freely and through different communication pathways. A new framework could be developed by promoting interdisciplinary collaboration and implementing standardized practices regarding data collection, curation, and sharing.

}, keywords = {cultural tipping point, dryland management, emerging technology, ryland research, sustainable management, technological tipping point}, doi = {10.1890/140161}, url = {/files/bibliography/15-007.pdf}, author = {Dawn M. Browning and A. Rango and Jason W. Karl and C. Laney and Enrique Vivoni and Craig Tweedie} } @conference {JRN54436, title = {The ecology of catastrophic events: understanding abrupt spatial transitions in susceptibility of grasslands and croplands to multi-year drought}, booktitle = {100th Annual Meeting of the Ecological Society of America}, year = {2015}, month = {08/2015}, address = {Baltimore, MD}, abstract = {

Much of the central grasslands region (CGR) of North America experienced a multi-year extreme drought in the 1930s that combined with land management practices to result in broad-scale plant mortality, massive dust storms, and losses of soil and nutrients. All grassland types in the CGR were affected, but to varying degrees. The southern mixedgrass prairie had the most severe impacts on vegetation and soil erosion; these grasslands were also well-studied by early eminent ecologists (e.g., Weaver, Albertson). In some areas, the transition between severely impacted and not impacted sites occurred over short distances, yet our understanding of the drivers of these abrupt transitions remains limited. For example, native prairie sites in southeastern Nebraska suffered high plant mortality while sites on similar soils located \< 100 km to the east in southwestern Iowa only had reductions in cover.\  Our goal was to synthesize historic data and maps from the 1920s to 1940s along this transition zone in order to determine the climatic, soil, and land use drivers of these abrupt changes in vegetation. We analyzed data through time from the literature for native grasslands and from the USDA Census of Agriculture for cropland to compare land use effects on vegetation change. Our results show that the transition from reductions in native grass cover in Iowa to increase in grass mortality in Nebraska in the 1930s drought was related to small increases in temperature and subtle decreases in precipitation along this spatial gradient. Although soil texture was similar, long-term plant available water decreased from east to west corresponding to an increase in grass mortality and increase in susceptibility to drought. Corn yields in the 1930s also decreased along this east to west gradient in plant available water with lower yields in Nebraska compared with Iowa. These abrupt transitions in vegetation would have resulted in an increase in susceptibility to multi-year drought, and an increase in erosion by wind and water through time in the native grasslands where grass mortality occurred. These cumulative effects of multi-year drought challenge our ability to predict ecosystem responses to catastrophic events without long-term data on these types of events.\  Abstract $\#$ PS-161.

}, author = {N. Dylan Burruss and Debra C. Peters and Jin Yao and Kris Havstad and Stacey L P Scroggs} } @conference {JRN54424, title = {Explaining abrupt spatial transitions in agro-ecosystem responses to periods of extended drought}, booktitle = {2015 LTER All Scientists Meeting}, year = {2015}, month = {08/2015}, abstract = {

During the 1930{\textquoteright}s, the North American central grassland region (CGR) experienced an extreme multi-year drought that resulted in broad scale plant mortality, massive dust storms and losses of soil and nutrients. Southern mixed grasslands were among the worst affected and experienced severe broad scale mortality.However, the severity of drought effects were varied in other grassland types of the CGR and in some instances responses formed spatially abrupt transitions between severe and minor drought impacts over short distances. This is exemplified in native grassland sites in southeastern Nebraska which suffered severe plant mortality while neighboring and ecologically similar sites in southwestern Iowa experienced reductions in cover. Additionally, a similar abrupt spatial transition was observed for crop production for the same area.\  Despite the environmental and economic consequences of the 1930{\textquoteright}s drought our understanding of the drivers of these abrupt spatial transitions remains limited. Our objectives were to use available long term data to: 1) characterize the spatial and temporal patterns in responses of native plants and crops before, during, and after the 1930s drought, and 2) to identify the climatic, soil, and land use drivers for the abrupt spatial transition in plant responses. We used corn production from the USDA Census of Agriculture for cropland as a proxy for grassland response. Published data and maps from the 1920{\textquoteright}s to 1940{\textquoteright}s along this transition zone were used to identify the climatic, soil and land use drivers contributing to abrupt transitions zones. Our results suggest the transition from reduction in grass cover in Iowa to severe grass mortality in Nebraska during the 1930{\textquoteright}s were the result of small increases in temperature and subtle decreases in precipitation along this spatial gradient. Additionally, long-term plant available water decreased from east to west corresponding to increased susceptibility to drought and ultimately increased grass mortality. These abrupt transitions in vegetation response would have resulted in an increase in ecosystem susceptibility to multi-year drought and, in grasslands where grass mortality occurred, increases in the rate of soil erosion by wind and water. Without long term data on these types of events cumulative effects of multiyear drought will continue to challenge our ability to predict ecosystem responses to catastrophic events.\  Paper No. 237.

}, author = {N. Dylan Burruss and Jin Yao and Kris Havstad and Stacey L P Scroggs} } @conference {JRN54443, title = {The effects of urbanization on trophic interactions in a desert landscape}, booktitle = {100th Annual Meeting of the Ecological Society of America}, year = {2015}, month = {08/2015}, address = {Baltimore, MD}, abstract = {

Background/Question/Methods: Trophic systems can be affected through top-down (predators) and bottom-up (resources) impacts. Human activity can alter trophic systems by causing predators to avoid areas (top-down) or by providing increased resources through irrigation and decorative plants that attract herbivores and their predators (bottom-up). Both processes may constrain the recruitment of herbaceous plants. We examined the effect of increasing urbanization within Las Cruces, NM, on a trophic system that included mammalian predators, mammalian prey, and herbaceous plants within natural shrubland vegetation. We tested the hypotheses that urbanization could cause a top-down effect in which predator abundance is reduced in more dense exurban areas, or urbanization could cause a bottom-up effect by providing food and water resources to support increased prey and predators. To test these hypotheses, we compared natural herbaceous plant recruitment, herbivory and granivory rates, rodent abundance, and lagomorph and carnivore activity across an urbanization gradient in Las Cruces, NM. The gradient included four replicates each of three development levels: high density exurban (0.40 ha lots), low density exurban (1.20 ha lots), and wildland (undeveloped). We used seedling and foraging trays to measure herbivory and granivory rates, live-trapping to estimate rodent abundance, and wildlife cameras to measure lagomorph and carnivore activity.\  Results/Conclusions: Supporting both top-down and bottom-up hypotheses, we found increased rates of herbivory on seedlings and decreased herbaceous plant recruitment in the most dense exurban areas. Patterns of overall rodent (kangaroo rat and pocket mouse) abundance, seed consumption rates, and jackrabbit activity did not vary with urbanization. However, we found increased cottontail activity in dense exurban areas. We also found increased predator (coyote) activity in dense exurban areas compared to wildlands, supporting the hypothesis that the effect of urbanization on plant recruitment is mediated by a bottom-up effect. Our results indicate that urbanization can have important indirect effects on natural vegetation.\  COS 112-3.

}, author = {Kristen Davanon and Lindsey Howard and Brandon T Bestelmeyer and Karen Mabry and Robert L. Schooley} } @conference {JRN54156, title = {The economics of Raramuri Criollo versus British crossbred cattle production in the Chihuahuan Desert}, booktitle = {68th Annual Society for Range Management Meeting}, year = {2015}, month = {01/2015}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Sacramento, CA}, abstract = {

Preliminary research indicates Raramuri Criollo cattle may range significantly further and forage in areas where traditional breeds rarely venture. They are thought to impose a lighter environmental footprint compared to their mainstream British crossbred counterparts. These small-frame animals are well adapted to harsh environments and maintain productivity with minimal inputs and supplementation. The objective of this research was to compare the economics of range-fed beef production with Raramuri Criollo cattle versus production of Hereford X Angus (H x A) cattle typically found on Chihuahuan Desert ranches. Enterprise budgets were developed for a 150 AUY (Animal Unit Yearlong) ranch using production and cost data for herds maintained at the USDA Jornada Experimental Range near Las Cruces, NM. Based on limited studies about differences in forage requirements, animal foraging behavior, and the potential improvements in distribution and forage use, we assumed the Criollo herd could be maintained at 180 AUY, a 20\% increase. With 2009-2013 average inflation-adjusted beef prices, net ranch returns from Raramuri Criollo cattle production was found to be 30\% higher than H x A production ($22,085 versus $16,978). The assumed 20\% increase in stocking rate was a major factor in the net return increase. Total cash costs were estimated to be 64\% less for Criollo production ($265/AUY versus $411/AUY). Notable cost differences included supplemental feed costs ($42/AUY versus $128/AUY) and veterinary, medicine and vaccine expenses ($6/AUY versus $28/AUY). The major factor favoring Criollo production was a strong demand for breeding animals with all Criollo heifers sold as bred heifers in the budget comparison. This meant for the 5-year average prices considered, a 2-year old Criollo heifer was worth nearly $1,000/head, exceeding the $900/head finished steer value. A limitation for Raramuri Criollo production was the extended period required to produce marketable range-fed animals. The typical cow/calf ranch sells calves after 8 months, requiring about 1.35 AUY/mature cow. By comparison, Criollo steers graze for 30 months and heifers for 24 months before sale. The smaller Criollo animals have a reduced forage requirement but the extended grazing period increases the total forage requirement to about 2 AUY/mature cow.

}, author = {Diaz, Jose and Torell, Allen and Richard E. Estell and Amy L. Gonzalez and Andr{\'e}s F. Cibils and D.M. Anderson} } @conference {JRN54441, title = {Effect of light intensity and wavelength on concentration of antiherbivory compounds in Flourensia cernua leaves}, booktitle = {Joint Annual Meeting ADSA - ASAS}, year = {2015}, month = {07/2015}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, address = {Orlando, FL}, abstract = {

Shrub encroachment negatively affects forage production and rangeland health in many semi-arid regions. Flourensia cernua (tarbush) has increased in the northern Chihuahuan Desert at the expense of grasslands. Our previous studies have shown a negative relationship between tarbush terpene concentrations and livestock herbivory. Concentrations of secondary compounds are affected by many biotic and abiotic factors, including amount and wavelength of solar radiation. A 3-year study was conducted to examine the impact of shade and UV light restriction on phenolic and terpene concentrations in tarbush. Our hypothesis was that UV restriction and partial shade would reduce carbon based secondary compounds. Sixty plants were randomly selected and assigned to 3 treatments (control, UV light restriction, or 50\% incident light restriction) in a randomized complete block. Frames covered with clear plastic film (UV blocking treatment), black shade cloth (50\% shade treatment) or frame only were placed over 20 plants each. Leaves were collected from each plant in late September each year and freeze-dried for total phenolic analysis (Folin-Denis method) or frozen for leaf surface terpene analysis (extracted with ethanol and identified and quantified with GCMS). Data were analyzed using repeated measures linear mixed effects models with treatment as the fixed effect and year as a repeated effect. Means were separated by LSD. Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Tarbush leaves contained 102 individual terpenes (includ{\textlnot}ing 19 unknowns). No year x treatment interactions were detected for any variable (P \> 0.05). Total phenolics did not differ between controls and UV restricted plants, but were lower for shaded plants than the other 2 treatments (P \< 0.05). Total volatiles were higher for the UV restriction treatment than controls (P \< 0.05), with shaded plants not differing from either treatment. Treatment effects were detected for 18 compounds (P \< 0.05). Shade reduced total phenolics as predicted, but did not affect total volatiles. In contrast to our expectations, UV restriction had no effect on total phenolics, and increased total volatile concentrations.\  Journal of Animal Science Supplement 93: Suppl. x3$\#$ W185/J:684.

}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James} } @conference {JRN54209, title = { Evaluating soil erodibility dynamics to improve estimates of wind erosion in drylands }, booktitle = {18th International Soil Conservation Organization Conference}, year = {2015}, month = {05/2015}, address = {El Paso, Texas}, abstract = {

Wind erosion is a key driver of land degradation in the world{\textquoteright}s drylands. Soil loss and nutrient decline due to wind erosion increase the sensitivity of drylands to climate stressors. Better understanding the factors controlling wind erosion in drylands will provide a basis for identifying and testing best management practice options. Much remains unknown about the role of dynamic soil surface properties, such as erodible sediment supply and soil crusting, in controlling rates of wind erosion. This research evaluates the role of changing soil surface conditions in controlling the susceptibility of soils to wind erosion. The objectives of this study were to: (1) determine the entrainment threshold for five different undisturbed dryland soils; (2) evaluate the magnitude of horizontal mass flux and its relation to the entrainment threshold at the studied sites; and (3) to identify the impact of annual seasons when evaluating the temporal variability in entrainment threshold and horizontal mass flux. Although large differences in sediment flux were present among sites, only minimal differences in threshold wind speed were found among them, despite large differences in soil surface conditions. The results suggest that sediment transport was influenced strongly by the availability of loose erodible sediment and soil abrasion processes during transport. Inclusion of these factors in wind erosion models may reduce model uncertainty, enabling more accurate assessments of wind erosion under different land use and land management scenarios.

}, author = {Magda Galloza and Nicholas Webb and Teddy M. Zobeck and Jeffrey E. Herrick} } @article {JRN54386, title = {Enhanced interannual precipitation variability increases plant functional diversity that in turn ameliorates negative impact on productivity}, journal = {Ecology Letters}, volume = {18}, year = {2015}, pages = {1293-1300}, abstract = {

Although precipitation interannual variability is projected to increase due to climate change, effects of changes in precipitation variance have received considerable less attention than effects of changes in the mean state of climate. Interannual precipitation variability effects on functional diversity and its consequences for ecosystem functioning are assessed here using a 6-year rainfall manipulation experiment. Five precipitation treatments were switched annually resulting in increased levels of precipitation variability while maintaining average precipitation constant. Functional diversity showed a positive response to increased variability due to increased evenness. Dominant grasses decreased and rare plant functional types increased in abundance because grasses showed a hump-shaped response to precipitation with a maximum around modal precipitation, whereas rare species peaked at high precipitation values. Increased functional diversity ameliorated negative effects of precipitation variability on primary production. Rare species buffered the effect of precipitation variability on the variability in total productivity because their variance decreases with increasing precipitation variance.

}, keywords = {arid zones, climate change, ecosystem functioning, functional diversity, grassland, interannual, precipitation variability, productivity, stability}, doi = {10.1111/ele.12523}, url = {/files/bibliography/15-028.pdf}, author = {Laureano A. Gherardi and O. E. Sala} } @article {JRN54387, title = {Enhanced precipitation variability decreases grass- and increases shrub-productivity}, journal = {Proceedings of the National Academy of Sciences}, volume = {112}, year = {2015}, pages = {12735-12740}, abstract = {

Although projections of precipitation change indicate increases in variability, most studies of impacts of climate change on ecosystems focused on effects of changes in amount of precipitation, overlooking precipitation variability effects, especially at the interannual scale. Here, we present results from a 6-y field experiment, where we applied sequences of wet and dry years, increasing interannual precipitation coefficient of variation while maintaining a precipitation amount constant. Increased precipitation variability significantly reduced ecosystem primary production. Dominant plantfunctional types showed opposite responses: perennial-grass productivity decreased by 81\%, whereas shrub productivity increased by 67\%. This pattern was explained by different nonlinear responses to precipitation. Grass productivity presented a saturating response to precipitation where dry years had a larger negative effect than the positive effects of wet years. In contrast, shrubs showed an increasing response to precipitation that resulted in an increase in average productivity with increasing precipitation variability. In addition, the effects of precipitation variation increased through time. We argue that the differential responses of grasses and shrubs to precipitation variability and the amplification of this phenomenon through time result from contrasting root distributions of grasses and shrubs and competitive interactions among plant types, confirmed by structural equation analysis. Under drought conditions, grasses reduce their abundance and their ability to absorb water that then is transferred to deep soil layers that are exclusively explored by shrubs. Our work addresses an understudied dimension of climate change that might lead to widespread shrub encroachment reducing the provisioning of ecosystem services to society.\ 

}, keywords = {ANPP, interannual variability, nonlinear response, plant-functional types, precipitation}, doi = {10.1073/pnas.1506433112}, url = {/files/bibliography/15-027.pdf}, author = {Laureano A. Gherardi and O. E. Sala} } @article {JRN54211, title = {Ecological challenges posed by climate uncertainty}, year = {2015}, pages = {8}, abstract = {

We{\textquoteright}ve been collecting long-term data at many ecological and agricultural research sites across the United States and globally, in some cases for over 100 years. This means we have a lot of data, and we feel like we understand our ecosystems very well{\textemdash}up until the climate drivers start changing beyond the range of historic variability. These changes make us nervous because they cause the rules between the physical drivers and the biota to change{\textemdash}and, in particular, during extreme events, including heat waves, freezes, floods, and droughts. It{\textquoteright}s very difficult for ecologists to deal with extreme events because we need long-term data to observe and understand events that rarely occur. Take something that occurs very infrequently, such as the Florida citrus freeze: How do we study that? How do we prepare for that? The other aspect of these events deals with space. A lot of ecological studies are small-plot studies, at a scale as small as a meter square in grasslands and up to a hectare in forests. You can imagine those plots don{\textquoteright}t represent very much area, and we have to do replications in order to understand these problems really well. What we really need to know is how to extrapolate these small-plot dynamics spatially so we can predict how large landscapes will respond to climate change. These large landscapes are difficult, if not impossible, to replicate. Propagating events{\textemdash}such as wildfires or species invasions{\textemdash}come into play when we put space and time together in what we call cross-scale interactions. These land{\textendash}atmosphere interactions that start small and propagate to have large impacts are the really big uncertainties that may become more frequent in the future as both the climate and land-use drivers change. Although our long-term data are invaluable at providing context for the present and future, the changing rules will make predictions of the future challenging without a strong understanding of the underlying mechanisms and their interactions that are driving those changes.

}, author = {Debra C. Peters} } @article {JRN54167, title = {Enhanced precipitation variability effects on water losses and ecosystem functioning: differential response of arid and mesic regions}, journal = {Climate Change}, volume = {131}, year = {2015}, month = {07/2015}, pages = {213-227}, chapter = {213}, abstract = {

Climate change will result in increased precipitation variability with more extreme events reflected in more frequent droughts as well as more frequent extremely wet conditions. The increase in precipitation variability will occur at different temporal scales from intra to inter-annual and even longer scales. At the intra-annual scale, extreme precipitation events will be interspersed with prolonged periods in between events. At the inter-annual scale, dry years or multi-year droughts will be combined with wet years or multi-year wet conditions. Consequences of this aspect of climate change for the functioning ecosystems and their ability to provide ecosystem services have been underexplored. We used a process-based ecosystem model to simulate water losses and soil-water availability at 35 grassland locations in the central US under 4 levels of precipitation variability (control, +25, +50+75 \%) and six temporal scales ranging from intra- to multi-annual variability. We show that the scale of temporal variability had a larger effect on soil-water availability than the magnitude of variability, and that inter- and multi-annual variability had much larger effects than intraannual variability. Further, the effect of precipitation variability was modulated by mean annual precipitation. Arid-semiarid locations receiving less than about 380 mm yr-1 mean annual precipitation showed increases in water availability as a result of enhanced precipitation variability while more mesic locations (\>380 mm yr-1) showed a decrease in soil water availability. The beneficial effects of enhanced variability in arid-semiarid regions resulted from a deepening of the soil-water availability profile and a reduction in bare soil evaporation. The deepening of the soil-water availability profile resulting from increase precipitation variability may promote future shifts in species composition and dominance to deeper-rooted woody plants for ecosystems that are susceptible to state changes. The break point, which has a mean of 380-mm with a range between 440 and 350 mm, is remarkably similar to the 370-mm threshold of the inverse texture hypothesis, below which coarse-texture soils had higher productivity than fine-textured soils.

}, keywords = {climate change, drought, model, precipitation variability, rainfall variability, soil-water availability}, doi = {10.1007/s10584-015-1389-z}, url = {/files/bibliography/15-013.pdf}, author = {O. E. Sala and Laureano A. Gherardi and Debra C. Peters} } @article {JRN54236, title = {Effects of Juniperus species and stage of maturity on nutritional, in vitro digestibility, and plant secondary compound characteristics}, journal = {Journal of Animal Science}, volume = {93}, year = {2015}, month = {08/2015}, pages = {4034-4047}, chapter = {4034}, abstract = {

Rising feed costs and recurring feed shortages necessitate the investigation into alternative and underutilized feed resources. Nutritional characteristics of Juniperus species are either unknown or limited to leaves and ground material from small stems. Thus, the objective was to quantify nutritional characteristics, 48-h true IVDMD (tIVDMD), microbial gas production, and secondary compound characteristics of entire woody plant material of four Juniperus species: J. pinchotii, J. monosperma, J. ashei, J. virginiana, at immature and mature stages of growth. Immature plants had greater CP concentrations and lower NDF concentrations (P \< 0.001) than mature plants regardless of species. Mature plants also had greater (P \< 0.001) concentrations of ADF compared to immature plants with the exception of J.virginiana. In general, immature J. pinchotii, J. monosperma and J.ashei had greater (P \< 0.02) tIVDMD, total 48-h and asymptotic gas production than mature plants. Immature J.monosperma and J.pinchotii\  plants were more digested (tIVDMD: P \< 0.001) than immature J.virginiana and J.ashei but tIVDMD did not differ in mature plant material across species. Condensed tannins (CT) were greater (P \< 0.001) in immature J.pinchotii and J.ashei than mature plants; differences in CT concentrations among immature species were also detected (P \< 0.04). Volatile oil yields were similar across maturity and species with one exception; immature J.pinchotii yielded greater (P \< 0.02) volatile oil than mature material. Volatile oil composition across species varied and contained a range of 65 to 70 terpene compounds. The dominant terpenes across species were generally greater (P \< 0.05) in immature vs. mature plant material with the exception of J.virginiana. Labdane acids were negligible in J.pinchotii, J.ashei, and J.virginiana, and greater in J.monosperma (P \< 0.001). Ground material from mature juniper species, although inferior in nutritional quality compared to immature plants, is comparable to traditional low-quality roughage ingredients. Given that ground J.pinchotii has been successfully fed in lamb feedlot diets and nutritional similarities of J.monosperma and J.ashei to J. pinchotii 47 combine to suggest potential of J.monosperma and J.ashei as effective roughage ingredient alternatives.

}, keywords = {in vitro digestibility, juniper, nutritional quality, secondary compounds, sheep, woody plants}, url = {/files/bibliography/15-015.pdf}, author = {Stewart, W. C. and Whitney, T.R. and Scholljegerdes, E.J. and Naumann, H.D. and Cherry, N.M. and Muir, J.P. and Lambert, B.D. and J.W. Walker and J. Rodger Adams and Welch, K.D. and D. R. Gardner and Richard E. Estell} } @article {JRN54290, title = {An ecosystem services perspective on brush management: research priorities for competing land-use objectives}, journal = {Journal of Ecology}, volume = {102}, year = {2014}, pages = {1394-1407}, abstract = {

1. The vegetation of semi-arid and arid landscapes is often comprised of mixtures of herbaceous and woody vegetation. Since the early 1900s, shifts from herbaceous to woody plant dominance, termed woody plant encroachment and widely regarded as a state change, have occurred world-wide. This shift presents challenges to the conservation of grassland and savanna ecosystems and to animal production in commercial ranching systems and pastoral societies.
2. Dryland management focused on cattle and sheep grazing has historically attempted to reduce the abundance of\  encroaching woody vegetation (hereafter, {\textquoteleft}brush management{\textquoteright}) with the intent of reversing declines in forage production, stream flow or groundwater recharge. Here, we assess the known and potential consequences of brush management actions, both positive and negative, on a broader suite of ecosystem services, the scientific challenges to quantifying these services and the trade-offs among them.
3. Our synthesis suggests that despite considerable investments accompanying the application of brush management practices, the recovery of key ecosystem services may be short-lived or absent. However, in the absence of such\  interventions, those and other ecosystem services may be compromised, and the persistence of grassland and savanna\  ecosystem types and their endemic plants and animals threatened.
4. Addressing the challenges posed by woody plant encroachment will require integrated management systems using diverse theoretical principles to design the type, timing and spatial arrangement of initial management actions and follow-up treatments. These management activities will need to balance cultural traditions and preferences, socio-economic constraints and potentially competing land-use objectives.
5. Synthesis. Our ability to predict ecosystem responses to management aimed at recovering ecosystem services where grasslands and savannas have been invaded by native or exotic woody plants is limited for many attributes (e.g. primary\  production, land surface{\textendash}atmosphere interactions, biodiversity conservation) and inconsistent for others (e.g. forage\  production, herbaceous diversity, water quality/quantity, soil erosion, carbon sequestration). The ecological community is challenged with generating robust information about the response of ecosystem services and their interactions if we are to position land managers and policymakers to make objective, science-based decisions regarding the many trade-offs and competing objectives for the conservation and dynamic management of grasslands and savannas.

}, keywords = {bush clearing, drylands, ecosystem services, shrub encroachment, state change, vegetation change, woody plant encroachment, woody weeds}, doi = {10.1111/1365-2745.12314}, url = {files/bibliography/JRN00621.pdf}, author = {Steven R. Archer and K. Predick} } @article {JRN54032, title = {Experimental micropedology-A technique for investigating soil carbonate biogenesis along a desert-grassland-forest transect, New Mexico, USA}, journal = {Spanish Journal of Soil Science}, volume = {4}, year = {2014}, pages = {1-18}, abstract = {

\ Manipulative experiments characterized by comparing treatments to controlsare widespread in scientific investigations. This study uses experimental micropedology to investigate whether soil microbes precipitate carbonate if a liquid growth-medium is applied to soil in situ. This was undertaken using apparatuses designed to (1) obtain micromorphological images of biogenic carbonate on microscope slides, (2) to quantify carbonate formation in fiberglass cloths, and (3) to measure associated carbon-isotope fractionations. The apparatuses were buried and harvested at monthly intervals from December 2010 to June 2011. The study was conducted along an ecological transect in New Mexico, USA, at three sites: a low-elevation desert (C3 shrubs), an intermediate-elevation steppe (C4 grasses), and a high-elevation forest (C3 conifers). In addition to comparing bioclimatic zones, the effect of parent material was also tested using paired limestone and igneous soils at each site. Soil samples in their natural state and inserted microscope slides were analyzed with binocular, petrographic, and scanning electron microscopy equipped with an x-ray microanalyser (EDS), and the fiberglass traps were analyzed with x-ray diffraction and a mass spectrometer for carbon concentrations and isotope ratios. Naturally occurring calcified microbes were found at each site in the form of calcified hyphae, needle fiber, and calcified root hairs, with the exception of the forest site on igneous parent material. Liquid growth medium induced microbial calcification regardless of whether the vegetation was desert shrubs, grassland, or forest, and regardless of whether the parent material was igneous or limestone. Thus, the ability of soil microorganisms to biomineralize carbonate when supplied with liquid growth medium in situ is a phenomenon that crosses biomes and is not limited to microbes endemic to either limestone or igneous parent material.

}, keywords = {biomineralization, needle-fiber calcite, pedogenic carbonates, soil micromorphology}, url = {files/bibliography/JRN54032.pdf}, author = {Khormali, F. and Curtis H. Monger and Curtis H. Monger} } @article {JRN54050, title = {Effects of grassland restoration efforts on mound-building ants in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {111}, year = {2014}, month = {12/2014}, pages = {79-83}, chapter = {79}, abstract = {

Shrub encroachment is a serious problem in arid environments worldwide because of potential reductions in ecosystem services and negative effects on biodiversity. In southwestern USA, Chihuahuan Desert grasslands have experienced long-term encroachment by shrubs including creosotebush (Larrea tridentata). Land managers have attempted an ambitious intervention to control shrubs by spraying herbicides over extensive areas to provide grassland habitat for wildlife species of conservation concern. To provide a broader assessment of how these restoration practices affect biodiversity, we evaluated responses by four mound-building ant species (Pogonomyrmex rugosus, Aphaenogaster cockerelli, Myrmecocystus depilis, and Myrmecocystus mexicanus). We compared colony densities between 14 pairs of treated areas (herbicide applied 10-30 years before sampling) and untreated areas (spatially matched and dominated by creosotebush). P. rugosus and A. cockerelli responded positively to restoration treatments likely due to an increased abundance of seeds associated with increased grass cover. Variation in P. rugosus densities among different-aged treatments suggests a substantial time lag in response that could reflect temporal changes in habitat quality or facilitation by a keystone rodent, Dipodomys spectabilis. Colony densities of the scavenging ant M. mexicanus were reduced on treated areas, and M. depilis exhibited a similar trend, likely reflecting a reduction of liquid food resources associated with shrubs. Our results demonstrate that ongoing efforts to restore Chihuahuan Desert grasslands are having both positive and negative effects on non-target taxa such as ants and support the need for a landscape mosaic approach to restoration. {\textcopyright} 2014 Published by Elsevier Ltd.

}, keywords = {aphaenogaster cockerelli, biodiversity, desert ants, landscape restoration, myrmecocystus depilis, Myrmecocystus mexicanus, Pogonomyrmex rugosus, shrub encroachment}, doi = {http://dx.doi.org/10.1016/j.jaridenv.2014.08.005}, url = {/files/bibliography/14-036.pdf}, author = {McAllister, Monica M. and Robert L. Schooley and Brandon T Bestelmeyer and John M. Coffman and Brad Cosentino} } @article {JRN54297, title = {Ecohydrology with Unmanned Aerial Vehicles}, journal = {Ecosphere}, volume = {5}, year = {2014}, chapter = {art130}, abstract = {

High-resolution characterizations and predictions are a grand challenge for ecohydrology. Recent advances in flight control, robotics and miniaturized sensors using unmanned aerial vehicles (UAVs) provide an unprecedented opportunity for characterizing, monitoring and modeling ecohydrologic systems at high-resolution (\<1 m) over a range of scales. How can the ecologic and hydrologic communities most effectively use UAVs for advancing the state of the art? This Innovative Viewpoints paper introduces the utility of two classes of UAVs for ecohydrologic investigations in two semiarid rangelands of the southwestern U.S. through two useful examples. We discuss the UAV deployments, the derived image, terrain and vegetation products and their usefulness for ecohydrologic studies at two different scales. Within a land-atmosphere interaction study, we utilize high-resolution imagery products from a rotary-wing UAV to characterize an eddy covariance footprint and scale up environmental sensor network observations to match the time-varying sampling area. Subsequently, in a surface and subsurface interaction study within a small watershed, we demonstrate the use of a fixed-wing UAV to characterize the spatial distribution of terrain attributes and vegetation conditions which serve as input to a distributed ecohydrologic model whose predictions compared well with an environmental sensor network. We also point to several challenges in performing ecohydrology with UAVs with the intent of promoting this new self-service (do-it-yourself) model for high-resolution image acquisition over many scales. We believe unmanned aerial vehicles can fundamentally change how ecohydrologic science is conducted and offer ways to merge remote sensing, environmental sensor networks and numerical models.

}, keywords = {ecology, environmental sensor network, hydrology, remote sensing, robotics, scaling, unmanned aircraft systems}, doi = {10.1890/ES14-00217.1}, url = {files/bibliography/JRN00623.pdf}, author = {Enrique Vivoni and A. Rango and C.A. Anderson and Nicole Pierini and A. P. Schreiner-McGraw and Srikanth Saripalli and Andrea S. Laliberte} } @article {JRN53949, title = {Effects of stocking rate on the variability of peak standing crop in a desert steppe of Eurasia grassland}, journal = {Environmental Management}, volume = {53}, year = {2014}, month = {02/2014}, pages = {266-273}, chapter = {266}, abstract = {

Proper grazing management practices can generate corresponding compensatory effects on plant community production, which may reduce inter-annual variability of productivity in some grassland ecosystems. However, it remains unclear how grazing influences plant community attributes and the variability of standing crop. We examined the effects of sheep grazing at four stocking rate treatments [control, 0 sheep ha-1 month-1; light (LG), 0.15 sheep ha-1 month-1; moderate (MG), 0.30 sheep ha-1 month-1; and heavy (HG), 0.45 sheep ha-1 month-1] on standing crop at the community level and partitioned by species and functional groups, in the desert steppe of Inner Mongolia, China. The treatments were arranged in a completely randomized block design over a 9-year period.\  Standing crop was measured every August from 2004 to 2012. Peak standing crop decreased (P\0.05) with increasing stocking rate; peak standing crop in the HG treatment decreased 40 \% compared to the control. May{\textendash}July precipitation explained at least 76 \% of the variation in peak standing crop. MG and HG treatments resulted in a decrease (P\0.05) in shrubs, semi-shrubs, and perennials forbs, and an increase (P\0.05) in perennial bunchgrasses compared to the control. The coefficients of variation at plant functional group and species level in the LG and MG treatments were lower (P\0.05) than in the control and HG treatments. Peak standing crop variability of the control and HG community were greatest, which suggested that LG and MG have greater ecosystem stability.

}, keywords = {ecosystem stability, peak standing crop, plant functional group, sheep grazing, Stipa breviflora Griseb}, doi = {10.1007/s00267-013-0186-6}, url = {/files/bibliography/14-001.pdf}, author = {Zhongwu Wang and Jiao, Shuying and G. Han and Mengli Zhao and Ding, Haijun and Xinjie Zhang and Xiaoliang Wang and E.L. Ayers and Walter Willms and Kris Havstad and Liu, Yongzhi} } @article {JRN54040, title = {Ecological site-based assessments of wind and water erosion: Informing accelerated soil erosion management in rangelands}, journal = {Ecological Applications}, volume = {24}, year = {2014}, month = {09/2014}, pages = {1405-1420}, chapter = {1405}, abstract = {

This paper explores how soil erosion assessments structured across ecological sites can inform systems for managing accelerated soil erosion in rangelands. We evaluated wind and water erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Our results show that wind and water erosion can be highly variable within and among ecological sites. Plots in shrub-encroached and shrub-dominated states were consistently susceptible to both wind and water erosion. However, grassland plots and plots with a grass-succulent mix had a high indicated susceptibility to wind and water erosion respectively. Vegetation thresholds for controlling erosion are identified that transcend the ecological sites and their respective states. The thresholds define vegetation cover levels at which rapid (exponential) increases in erosion rates begin to occur, suggesting that erosion in the study ecosystem can be effectively controlled when bare ground cover is \<20\% of a site or total ground cover is \>50\%. Similarly, our results show that erosion can be controlled when the cover of canopy interspaces \>50 cm in length reaches ~50\%, the cover of canopy interspaces \>100 cm in length reaches ~35\% or the cover of canopy interspaces \>150 cm in length reaches ~20\%. This process-based understanding can be applied, along with knowledge of the differential sensitivity of vegetation states, to improve erosion management systems. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of sites to erosion. Land use impacts that are constrained within the natural variability of sites should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds and natural variability of ecological sites will enable improved identification of where and when accelerated soil erosion occurs and the development of practical management solutions.

}, keywords = {accelerated soil erosion, aeolian, agriculture, anthropogenic dust, dryland, land use change, state-and-transisiton models, sustainability, threshold}, url = {/files/bibliography/14-027.pdf}, author = {Nicholas Webb and Jeffrey E. Herrick and Danielle Duni} } @article {JRN53969, title = {The effect of roughness elements on wind erosion: The importance of surface shear stress distribution}, journal = {Journal of Geophysical Research: Atmospheres}, volume = {119}, year = {2014}, month = {05/2014}, pages = {6066-6084}, chapter = {6066}, abstract = {

Representation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Drag partitioning schemes are used to account for roughness by scaling the soil entrainment threshold by the ratio of shear stress on roughness elements to that on the vegetated land surface. This approach does not explicitly account for the effects of roughness configuration, which may be important for sediment flux. Here we investigate the significance of roughness configuration for Aeolian sediment transport, the ability of drag partitioning approaches to represent roughness configuration effects, and the implications for model accuracy. We use wind tunnel measurements of surface shear stress distributions to calculate sediment flux for a suite of roughness configurations, roughness densities, and wind velocities. Roughness configuration has a significant effect on sediment flux, influencing estimates by more than 1 order of magnitude. Measured and modeled drag partitioning approaches overestimate the predicted flux by 2 to 3 orders of magnitude. The drag partition is sensitive to roughness configuration, but current models cannot effectively represent this sensitivity. The effectiveness of drag partitioning approaches is also affected by estimates of the aerodynamic roughness height used to calculate wind shear velocity. Unless the roughness height is consistent with the drag partition, resulting fluxes can show physically implausible patterns. These results should make us question current assessments of the magnitude of vegetated dryland dust emissions. Representing roughness effects on surface shear stress distributions will reduce uncertainty in quantifying wind erosion, enabling better assessment of its impacts and management solutions.

}, doi = {10.1002/2014JD021491}, url = {/files/bibliography/14-020.pdf}, author = {Nicholas Webb and Gregory S. Okin and Brown, Shannon} } @article {49854, title = {Evaluation of a new model of aeolian transport in the presence of vegetation}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {118}, year = {2013}, month = {04/2013}, pages = {288-306}, chapter = {288}, abstract = {

Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation [Okin, 2008]. This approach differs from previous models by accounting for how vegetation affects the distribution of shear velocity on the surface rather than merely calculating the average effect of vegetation on surface shear velocity or simply using empirical relationships. Vegetation, soil, and meteorological data at 65 field sites with measurements of horizontal aeolian flux were collected from the Western United States. Measured fluxes were tested against modeled values to evaluate model performance, to obtain a set of optimum model parameters, and to estimate the uncertainty in these parameters. The same field data were used to model horizontal aeolian flux using three other schemes. Our results show that the Okin [2008] model can predict horizontal aeolian flux with an approximate relative error of 2.1 and that further empirical corrections can reduce the approximate relative error to 1.0. The level of error is within what would be expected given uncertainties in threshold shear velocity and windspeed at our sites. The model outperforms the alternative schemes both in terms of approximate relative error as well as the number of sites at which threshold shear velocity was exceeded. These results lend support to an understanding of the physics of aeolian transport in which 1) vegetation{\textquoteright}s impact on transport is dependent upon the distribution of vegetation rather than merely its average lateral cover, and 2) vegetation impacts surface shear stress locally by depressing it in the immediate lee of plants rather than by changing the bulk surface{\textquoteright}s threshold shear velocity. Our results also suggest that threshold shear velocity is exceeded more than might be estimated by single measurements of threshold shear stress and roughness length commonly associated with vegetated surfaces, highlighting the variation of threshold shear velocity with space and time in real landscapes.

}, doi = {10.1002/jgrf.20040 }, url = {/files/bibliography/13-013.pdf}, author = {Junran Li and Gregory S. Okin and Jeffrey E. Herrick and Jayne Belnap and M. Miller and Vest, Kimberley and Draut, Amy E.} } @article {49860, title = {Ecosystem resilience despite large-scale altered hydroclimatic conditions}, journal = {Nature}, volume = {494}, year = {2013}, month = {2013}, pages = {349-352}, chapter = {349}, abstract = {

Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological model for many regions1. Largescale, warm droughts have recently occurred in North America, Africa, Europe, Amazonia and Australia, resulting in major effects on terrestrial ecosystems, carbon balance and food security2,3. Here we compare the functional response of above-ground net primary production to contrasting hydroclimatic periods in the late twentieth century (1975{\textendash}1998), and drier, warmer conditions in the early twenty-first century (2000{\textendash}2009) in the Northern and Southern Hemispheres. We find a common ecosystem water-use efficiency (WUEe: above-ground net primary production/evapotranspiration) across biomes ranging from grassland to forest that indicates an intrinsic system sensitivity to water availability across rainfall regimes, regardless of hydroclimatic conditions. We found higher WUEe in drier years that increased significantly with drought to a maximum WUEe across all biomes; and a minimum native state in wetter years that was common across hydroclimatic periods. This indicates biome-scale resilience to the interannual variability associated with the early twenty-first century drought{\textemdash}that is, the capacity to tolerate low, annual precipitation and to respond to subsequent periods of favourable water balance. These findings provide a conceptual model of ecosystem properties at the decadal scale applicable to the widespread altered hydroclimatic conditions that are predicted for later this century. Understanding the hydroclimatic threshold that will break down ecosystem resilience and alter maximum WUEe may allow us to predict land-surface consequences as large regions become more arid, starting with waterlimited, low-productivity grasslands.

}, keywords = {aboveground net primary production, air temperature, ANPP, climate change, drought, ecosystem resilience, evapotranspiration, hydroclimate, MODIS, plant production, precipitation}, doi = {10.1038/nature11836}, url = {/files/bibliography/13-022.pdf}, author = {Guillermo E. Ponce-Campos and S. Moran and Alfredo Huete and Yongguang Zhang and Bresloff, Cynthia and T. Huxman and Eamus, Derek and David D. Bosch and Anthony R. Buda and Stacey A. Gunter and Scalley, Tamara Heartsill and S.G. Kitchen and M.P. McClaran and McNab, W. Henry and Montoya, Diane S. and Jack A. Morgan and Debra C. Peters and John Sadler and M. S. Seyfried and Paul F. Starrs} } @article {49863, title = {Earth Stewardship of rangelands: coping with ecological, economic, and political marginality}, journal = {Frontiers in Ecology and the Environment}, volume = {11}, year = {2013}, month = {09/2013}, pages = {348-354}, chapter = {348}, abstract = {

Rangelands encompass 30\–40\% of Earth\’s land surface and support 1 to 2 billion people. Their predominant use is extensive livestock production by pastoralists and ranchers. But rangelands are characterized by ecological, economic, and political marginality, and higher value, more intensive land uses are impinging on rangelands around the world. Earth Stewardship of rangelands must address both livestock management and the broader socioecological dynamics that promote land-use changes, fragmentation, and degradation. We identify specific gradients on which human\–rangeland systems can be arrayed, including issues of variability, adaptation to disturbance, commercialization, land-use change, land-tenure security, and effective governance, and we illustrate the gradients\’ interactions and effects in sites worldwide. The result is a synthetic framework to help in understanding how rangeland Earth Stewardship can be achieved in the face of marginality, globalization, and climate change.

}, keywords = {climate change, Earth Stewardship, globalization, marginality, rangeland management, socioecological dynamics}, doi = {10.1890/120333}, url = {/files/bibliography/13-025.pdf}, author = {N. F. Sayre and McAllister, Ryan R. J. and Brandon T Bestelmeyer and Moritz, Mark and M.G. Turner} } @conference {JRN53993, title = {Ecological site concepts for the Caldenal ecoregion}, booktitle = {Los Pastizales y el Hombre, producir y conservar}, year = {2013}, month = {03/2013}, address = {Santa Rosa, La Pampa, Argentina}, abstract = {

Ecological site (ES) concepts describe potential vegetation and ecological mechanisms of plant community change within specific soil, geomorphic and climate conditions.\  In this study, a preliminary definition of ES concepts for the caldenal ecoregion was developed by exploring the relationship between landform, soil and vegetation based on 42 sample sites. Woody plant dominance was characterized by plant density (Open, Closed and Fachinal [thicket]), and height (Tall and Short). Herbaceous species composition was grouped in five functional groups: the palatable summer and thin-leaved winter grasses, and the unpalatable winter bunch grasses, forbs, and annuals.\  Ward{\textquoteright}s cluster analysis was used to group sampling sites based on their soil properties along with vegetation characteristics.\  Cluster analysis indicated six distinct plant communities that were easily interpreted.\  Open Calden states were found in dunes and sandy plateaus, while thicketized states (Closed and Fachinal) occurred on soils with greater silt-clay content on hillsides, valleys and plains.\  A short fachinal state was associated with shallow caliche layer (\<0.5 m) and high carbonate levels.\  Open and Closed types were dominated by Prosopis caldenia while the Fachinal was dominated by Condalia microphyla.\  Palatable grasses were more highly associated with Open sites; however all sites showed a large proportion of unpalatable herbaceous species. The ecological sites derived from this analysis can serve as a basis for recognizing different levels of vulnerability to encroachment and change in grass species composition. This study provides a framework for future data collection to further refine ES concepts in the Caldenal.

}, author = {L.N. Svejcar and Brandon T Bestelmeyer and H. Raul Peinetti and Edgardo Adema and Sosa, A.A.} } @article {49864, title = {Effect of image spatial and spectral characteristics on mapping semi-arid rangeland vegetation using multiple endmember spectral mixture analysis (MESMA)}, journal = {Remote Sensing of Environment}, volume = {132}, year = {2013}, month = {01/2013}, pages = {120-130}, chapter = {120}, abstract = {

Encroachment of invasive shrubs into grassland areas on rangelands in the southwestern United States threatens the viability of livestock production and can severely alter hydrology and biodiversity.\  Novel remote sensing technologies may provide useful information for monitoring and remediating this threat.\  The objectives were to investigate multiple endmember spectral mixture analysis (MESMA) as an approach to map rangeland vegetation using hyperspectral remote sensing imagery and to test the sensitivity of MESMA to alternative image spatial resolutions and spectral waveband combinations. Data from two Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) overflights at the Jornada Experimental Range in southwestern New Mexico were used in the analysis. Endmember spectra were selected from a library of ground-based spectral observations collected with a field spectroradiometer. A 4-endmember MESMA was conducted for both AVIRIS images at their native spatial resolutions using 113 10-nm wavebands from 422 to 2339 nm. Additional MESMAs were conducted at 10 multiples of the images{\textquoteright} native spatial resolution and for 6 alternative combinations of spectral waveband subregions.\  Maps of endmember fractional cover for green shrub vegetation, nonphotosynthetic grass vegetation, and bare soil were comparable to an earlier vegetation classification map of Jornada. MESMA fractional cover estimates for the green vegetation endmember were positively correlated with the normalized difference vegetation index (NDVI) with correlation coefficients (r) greater than 0.58.\  Correlation coefficients between the sum of the green and nonphotosynthetic vegetation endmembers and the cellulose absorption index (CAI) were greater than 0.59. Correlation coefficients between MESMA fractional green vegetation cover and NDVI for independent multispectral images were greater than 0.57.\  Despite obvious losses in spatial detail at coarser image spatial resolutions, MESMA results for images with spatial resolution degraded by a factor of 10 (~150 m) were quite similar to aggregated results for MESMA at the native spatial resolution (~15 m).\  Additionally, MESMA results were shown to be substantially more sensitive to the spectral wavebands used in the analysis as compared to the spatial resolution of the images.\  Considered together, the MESMA results at Jornada indicate that fine spectral resolution with hyperspectral remote sensing is substantially more important than incremental changes in image spatial scale from 15 m to 150 m.

}, keywords = {AVIRIS, cresotebush, grass, Hyperspectral, HyspIRI, Imaging speactroscopy, mesquite, NDVI, Nonphotosynthetic, spatial scale, Spectra, VAI}, doi = {10.1016/j.rse.2013.01.008}, url = {/files/bibliography/13-006.pdf}, author = {Thorp, Kelly R. and A.N. French and A. Rango} } @article {49867, title = {Effects of adding protein, condensed tannins, and polyethylene glycol to diets of sheep and goats fed one-seed juniper and low quality roughage}, journal = {Small Ruminant Research}, volume = {112}, year = {2013}, month = {04/2013}, pages = {56-68}, chapter = {56}, abstract = {

The biochemical mechanisms that limit voluntary intake of one-seed juniper by browsing ruminants are not well understood. Twelve Rambouillet ewes (78 \± 2.3 kg BW) and 12 Boer-Spanish does (54 \± 1.4 kg BW) were used in a split-plot sequence design to investigate the effects of adding protein, quebracho tannins (QTs), and polyethylene glycol (PEG) on one-seed juniper intake and preference and on ruminal VFA and plasma AA concentrations. Animals received sudangrass hay and isoenergetic basal diets (4 does and 4 ewes/diet) with either rumen degradable (RDP) or rumen undegradable (RUP) protein (12.5\% CP) or no additional protein (control, 5\% CP) during four 15-d periods. The control, RDP, and RUP diets were considered the main plot, whereas the four supplement treatments were analyzed as the split-plot effects. Period 1 allowed for adaptation to basal diets and served as a baseline phase. In periods 2-4, animals were offered juniper leaves and twigs (period 2), juniper plus QT (10\% of basal diet; period 3), and juniper plus QT plus PEG (50 g/animal; period 4). Juniper intake by sheep and goats was not affected (P \> 0.88) by RDP or RUP when animals were first exposed to juniper, but marginally increased (P \< 0.10) in period 4 (QT + PEG) regardless of the basal diet. Prior exposure to juniper did not affect (P = 0.61) the preference ratio for juniper, but goats had higher preference ratio for juniper (P \< 0.01) when receiving PEG (period 4). Concentrations of total VFA tended to increase in sheep (P = 0.10) and goats (P = 0.14) fed protein supplements and molar proportions shifted toward acetate for goats fed RDP and RUP (P = 0.07) and to butyrate for sheep fed RDP (P = 0.01). Initial juniper exposure (period 2) elevated concentrations of acetate, propionate, and butyrate (P \< 0.01), but the effect was extinguished in periods 3 and 4 with addition of QT (P \< 0.05). Supplementation with PEG transiently mitigated the depressor effect of QT on acetate, propionate, and butyrate concentration at 12 h post juniper feeding (P \< 0.01). RDP in goats and to a greater extent RUP in sheep increased plasma concentrations of various AA, especially the branched chained Val, Ile, and Leu (P \< 0.05). Plasma concentrations of several AA, including Met, Cyst, Glu, Gly, Gln, Asn, Thr, Ser, and Phe, decreased with ingestion of juniper (period 2) and juniper plus QT (period 3). Concentrations of some AA that were depressed by ingestion of juniper and QT were partially restored with supplemental PEG (P \< 0.05). Protein, terpenes, tannins, and PEG interacted to influence rumen VFA and plasma AA, which were related to intake of juniper and basal diets.

}, keywords = {goats, juniper, rumen degradabe protein, rumen undegradable protein, sheep, terpenes}, doi = {10.1016/j.smallrumres.2012.09.006}, url = {/files/bibliography/13-012.pdf}, author = {S. A. Utsumi and Andr{\'e}s F. Cibils and Richard E. Estell and S. Soto-Navarro and Cheng, L. and Hallford, D.M.} } @article {JRN54177, title = {Estimating suitable environments for invasive plant species across large landscapes: A remote sensing strategy using Landsat 7 ETM+}, journal = {International Journal of Biodiversity and Conservation}, volume = {5}, year = {2013}, month = {2013}, pages = {122-134}, chapter = {122}, abstract = {

The key to reducing ecological and economic damage caused by invasive plant species is to locate and eradicate new invasions before they threaten native biodiversity and ecological processes. We used Landsat Enhanced Thematic Mapper Plus imagery to estimate suitable environments for four invasive plants in Big Bend National Park, southwest Texas, using a presence-only modeling approach. Giant reed (Arundo donax), Lehmann lovegrass (Eragrostis lehmanniana), horehound (Marrubium vulgare) and buffelgrass (Pennisteum ciliare) were selected for remote sensing spatial analyses. Multiple dates/seasons of imagery were used to account for habitat conditions within the study area and to capture phenological differences among targeted species and the surrounding landscape. Individual species models had high (0.91 to 0.99) discriminative ability to differentiate invasive plant suitable environments from random background locations. Average test area under the receiver operating characteristic curve (AUC) ranged from 0.91 to 0.99, indicating that plant predictive models exhibited high discriminative ability to differentiate suitable environments for invasive plant species from random locations. Omission rates ranged from \<1.0 to 18\%. We demonstrated that useful models estimating suitable environments for invasive plants may be created with \<50 occurrence locations and that reliable modeling using presence-only datasets can be powerful tools for land manager

}, keywords = {invasive species, Landsat 7 ETM+, Maxent, presence-only modeling}, url = {/files/bibliography/13-040.pdf}, author = {Kendal Young and Laurie Abbott and Caldwell, Colleen and Scott T. Schrader} } @article {JRN54215, title = {Extreme precipitation patterns and reductions of terrestrial ecosystem production across biomes}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {118}, year = {2013}, month = {01/2013}, pages = {148-157}, chapter = {148}, abstract = {

Precipitation regimes are predicted to shift to more extreme patterns that are characterized by more heavy rainfall events and longer dry intervals, yet their ecological impacts on vegetation production remain uncertain across biomes in natural climatic conditions. This in situ study investigated the effects of these climatic conditions on aboveground net primary production (ANPP) by combining a greenness index from satellite measurements and climatic records during 2000{\textendash}2009 from 11 long-term experimental sites in multiple biomes and climates. Results showed that extreme precipitation patterns decreased the sensitivity of ANPP to total annual precipitation (PT) at the regional and decadal scales, leading to decreased rain use efficiency (RUE; by 20\% on average) across biomes. Relative decreases in ANPP were greatest for arid grassland (16\%) and Mediterranean forest (20\%) and less for mesic grassland and temperate forest (3\%). The cooccurrence of heavy rainfall events and longer dry intervals caused greater water stress conditions that resulted in reduced vegetation production. A new generalized model was developed using a function of both PT and an index of precipitation extremes and improved predictions of the sensitivity of ANPP to changes in precipitation patterns. Our results suggest that extreme precipitation patterns have substantially negative effects on vegetation production across biomes and are as important as PT. With predictions of more extreme weather events, forecasts of ecosystem production should consider these nonlinear responses to altered extreme precipitation patterns associated with climate change.

}, doi = {10.1029/2012JG002136}, url = {/files/bibliography/13-041.pdf}, author = {Yongguang Zhang and S. Moran and Mark A. Nearing and Guillermo E. Ponce-Campos and Alfredo Huete and Anthony R. Buda and David D. Bosch and Stacey A. Gunter and S.G. Kitchen and McNab, W. Henry and Jack A. Morgan and M.P. McClaran and Montoya, Diane S. and Debra C. Peters and Paul F. Starrs} } @article {49871, title = {Empirical assessment of state-and-transition models with a long-term vegetation record from the Sonoran Desert}, journal = {Ecological Applications}, volume = {22}, year = {2012}, month = {03/2012}, pages = {400-411}, chapter = {400}, abstract = {Resilience-based frameworks, including state-and-transition models (STM), are being increasingly called upon to inform policy and guide ecosystem management, particularly in rangelands. Yet, multiple challenges impede their effective implementation: (1) paucity of empirical tests of resilience concepts, such as alternative states and thresholds, and (2) heavy reliance on expert models, which are seldom tested against empirical data. We developed an analytical protocol to identify unique plant communities and their transitions, and applied it to a long-term vegetation record from the Sonoran Desert (1953\–2009). We assessed whether empirical trends were consistent with resilience concepts, and evaluated how they may inform the construction and interpretation of expert STMs. Seven statistically distinct plant communities were identified based on the cover of 22 plant species in 68 permanent transects. We recorded 253 instances of community transitions, associated with changes in species composition between successive samplings. Expectedly, transitions were more frequent among proximate communities with similar species pools than among distant communities. But unexpectedly, communities and transitions were not strongly constrained by soil type and topography. Only 18 transitions featured disproportionately large compositional turnover (species dissimilarity ranged between 0.54 and 0.68), and these were closely associated with communities that were dominated by the common shrub (burroweed, Haplopappus tenuisecta; indicating that only some, and not all, communities may be prone to large compositional change. Temporal dynamics in individual transects illustrated four general trajectories: stability, nondirectional drift, reversibility, and directional shifts that were not reversed even after 2\–3 decades. The frequency of transitions and the accompanying species dissimilarity were both positively correlated with fluctuation in precipitation, indicating that climatic drivers require more attention in STMs. Many features of the expert models, including the number of communities and participant species, were consistent with empirical trends, but expert models underrepresented recent increases in cacti while overemphasizing the introduced Lehmann\’s lovegrass (Eragrostis lehmanniana). Quantification of communities and transitions within long-term vegetation records presents several quantitative metrics such as transition frequency, magnitude of accompanying compositional change, presence of unidirectional trajectories, and lack of reversibility within various timescales, which can clarify resilience concepts and inform the construction and interpretation of STMs.}, keywords = {alternative stable states, cluster analysis, detrended corrrespondence analysis, dynamic regimes, nonequilibrium theory, rangeland management, regime shifts, thresholds}, url = {/files/bibliography/12-021.pdf}, author = {Bagchi, Sumanta and D.D. Briske and X. Ben Wu and M.P. McClaran and Brandon T Bestelmeyer and Maria Fern{\'a}ndez-Gim{\'e}nez} } @proceedings {JRN54525, title = {Evaluating plant community responses to rainfall extremes in southwest U.S. ecosystems using radiometric change detection}, volume = {COS 174-3}, year = {2012}, month = {08/2012}, publisher = {Ecological Society of America}, address = {Portland, Oregon}, abstract = {Spatially-explicit depictions of plant productivity and biomass over large areas are critical to monitoring landscapes in highly heterogeneous arid and semi-arid ecosystems. Radiometric change detection techniques applied to Landsat Thematic Mapper (TM) imagery provide an opportunity to characterize changes in land surface conditions that are relevant to land managers. Importantly, these techniques are straightforward and readily transferable to those without expertise in remote sensing. We sought to answer three questions: (1) can we use differences between pre- and post-growing season spectral vegetation index values (i.e., normalized difference vegetation index (NDVI)) to locate areas of extreme change in vegetation? (2) in what ecological sites do these areas of extreme change occur? and (3) can extreme changes in vegetation be related to vegetation dynamics conceptualized in state-and-transition models. We calculated the difference between NDVI values representing pre- (May) and post- (September/October) growing season conditions, standardized NDVI difference values to Z-scores to identify areas of extreme high and low change over the growing season, and determined the plant and soil features associated with significantly high or low NDVI difference values. Calculations were made for two years selected to represent below- (2003) and above-(2009) average rainfall conditions. Two percent of the 5696 km2 study area experienced significant reduction in NDVI values in 2003. The extreme reductions in NDVI values in 2003 were most commonly observed in Rockland and Hills ecological sites in a Historical Savanna state, but were also observed on an area of Clay Loam Upland in a Historical Grassland state. Interestingly, part of this Clay Loam Upland area also demonstrated an extreme increase in NDVI over the wet 2009 growing season. Such responses to wet and dry years detected by NDVI could portend community phase changes within the Historical Grassland state or a transition to an alternative state. The NDVI difference in 2009 following above-average rainfall in 2006 and 2008 resulted in 3.7\% of the area experiencing a significant increase between May and Sep. The largest most contiguous patches of significant increase in NDVI occurred on the Clay Loam Upland ecological site and correspond to the Historical Grassland state. The vegetation index differencing method and translation of growing season differences to Z-scores permit examination of changes over large areas and can be applied by non-experts. Use of additional image dates could enhance interpretations of vegetation dynamics, focus field reconnaissance efforts, and become a routine operational work flow for natural resource managers.}, author = {Dawn M. Browning and Caitriana Steele} } @article {JRN54552, title = {Effect of supplementing activated charcoal on the intake of honey mesquite leaves by lambs}, journal = {Journal of Animal Science}, volume = {90 (Suppl. 3) }, year = {2012}, month = {07/2012}, chapter = {p. 148}, abstract = {A study was conducted to determine if intake of honey mesquite (Prosopis glandulosa Torr.) leaves by sheep could be increased by supplementing activated charcoal at 0.0, 0.33, 0.67 or 1.00 g / kg of body weight. Twenty wether lambs (36.6 {\textpm} 0.6 kg) were randomly assigned to the 4 treatment levels. Lambs were fed low-quality Sudan-grass hay at 2\% of BW plus 80 g/d of molasses for 7 d, and Sudan-grass hay at 1.9\% of BW plus 80 g/d of molasses mixed with the assigned level of activated charcoal for 16 d (d 8 to 23). On d 8 to 23, lambs were also given ad libitum access to honey mesquite leaves that had been previously harvested, frozen, and thawed immediately before feeding. Repeated measures analyses were used to determine if level of activated charcoal fed to lambs affected daily intake of mesquite leaves. No differences (P = 0.52) in intake of mesquite leaves were detected. Mean intake of mesquite leaves was 20.7 {\textpm} 3.7, 23.8 {\textpm} 3.8, 20.2 {\textpm} 3.7, and 27.3 {\textpm} 3.7 g/d for 0.0, 0.33, 0.67 and 1.0 treatment levels, respectively. Consumption of mesquite leaves varied greatly among lambs, ranging from 1.4 to 7.4\% of their diet during the last 8 d of the study. No differences in hay intake (P = 0.23) or lamb weight gain (P = 0.58) were detected among supplemental charcoal treatments. Future studies examining the consumption of honey mesquite leaves by sheep should consider the potential variability in intake among individual animals.}, keywords = {rangeland, secondary compounds, sheep}, url = {files/bibliography/12-JAS-Mayagoitia-Gonzalez.pdf}, author = {P. E. Mayagoitia-Gonzalez and C. Donovan Bailey and Richard E. Estell} } @proceedings {49893, title = {Effect of supplementing activated charcoal on the intake of honey mesquite leaves by lambs}, volume = {63}, year = {2012}, month = {08/2012}, pages = {7-9}, publisher = {American Society of Animal Science}, address = {Phoenix, AZ}, abstract = {A study was conducted to determine if intake of honey mesquite (Prosopis glandulosa Torr.) leaves by sheep could be increased by supplementing four levels of activated charcoal supplemental (0.0, 0.33, 0.67 and 1.00 g/kg of BW). Twenty wether lambs (36.6 \± 0.6 kg) were randomly assigned to the 4 treatment levels. Lambs were fed 2.0\% of body weight of low-quality Sudan-grass hay (Sorghum bicolor) and 80 g/d of molasses for 7 days, and then for following 16 days lambs were fed 1.9\% of body weight of low-quality Sudan-grass hay and 80 g /day of molasses mixed with the assigned level of activated charcoal. After the 7-d acclimation period, lambs were also given ad libitum access to honey mesquite leaves that had been thawed before feeding. Repeated measures analyses were used to determine if level of activated charcoal fed to lambs affected daily intake of mesquite leaves. No differences (P = 0.52) in the intake of mesquite leaves were detected. Mean intake of mesquite leaves was 20.7 \± 3.7, 23.8 \± 3.8, 20.2 \± 3.7, and 27.3 \± 3.7 g/day for the 0.0, 0.33, 0.67 and 1.0 levels, respectively. Consumption of mesquite leaves varied greatly among lambs, ranging from 1.24 to 6.25\% of the diet. Differences in hay intake (P = 0.23) and lamb weight gain (P = 0.58) were not detected among supplemental charcoal treatments. Future studies examining the consumption of honey mesquite leaves by sheep should consider the potential variability in intake among individual animals.}, keywords = {activated charcoal, honey mesquite, molasses, Sudan-grass hay, wethers}, url = {/files/bibliography/12-025.pdf}, author = {P. E. Mayagoitia-Gonzalez and C. Donovan Bailey and Richard E. Estell} } @proceedings {JRN54535, title = {Effects of interannual precipitation variability on ecosystem water balance and its consequences for aboveground net primary production}, volume = {OOS 12-6}, year = {2012}, month = {08/2012}, publisher = {Ecological Society of America Abstracts}, address = {Portland, Oregon}, abstract = {Climate change will result in an increase in the variability of precipitation within and among years as a result of different atmospheric phenomena. For many locations, there will be larger precipitation events interspersed with longer periods of droughts within a year, and more sequences of extreme dry years followed by multi-year extremely wet periods. Here, we focused on the inter-annual scale and hypothesize that increased inter-annual variability in precipitation will differentially affect the major components of water loss from arid to subhumid ecosystems. We expect this variability will have consequences for the amount of water available to plants for primary production. We tested our hypothesis using the model SOILWAT parameterized for arid (Jornada Basin) and mesic (Konza Prairie) grassland sites in the US. SOILWAT is a multi-layer, daily time-step model that simulates soil water content by depth in the soil profile. We increased precipitation variability at the inter-annual scale by randomly adding or subtracting a percentage of daily precipitation for each year in the 100-year record. Thus, total precipitation was the same as the control simulations, but the variability was 25\% higher. We repeated the exercise for 25, 50, 75, and 100\% increased variability. Our results show that increased interannual precipitation variability increased plant available water in the arid site and decreased it in the mesic site. High variability resulted in a high frequency of large rainfall events, which in turn resulted in a downward shift of the distribution of water availability in the soil profile that reduced bare-soil evaporative losses and enhanced deep percolation losses. Therefore, an increase in variability decreased losses in arid ecosystems where losses occurred predominantly via bare-soil evaporation. On the contrary, increased precipitation variability increased losses in the mesic ecosystem, where major losses occurred via deep percolation. Given the tight relationship that exists between transpiration and photosynthesis, we expect that an increase in precipitation interannual variability will increase productivity in the arid site and reduce it in the mesic site.}, author = {O. E. Sala and Laureano A. Gherardi and Debra C. Peters} } @article {49913, title = {Effects of seasonal grazing, drought, fire, and carbon enrichment on soil icroarthropods in a desert grassland}, journal = {Journal of Arid Environments}, volume = {83}, year = {2012}, month = {06/01/2012}, pages = {10-14}, chapter = {10}, abstract = {

This study was designed to test hypotheses about the combined effects of short-term, seasonal grazing with seasonal drought, fire, and carbon enrichment on soil microarthropod communities in a Chihuahuan Desert grassland. The study was conducted in eighteen 0.5 ha plots following three consecutive years of treatment: six plots intensively grazed in summer, six in winter, and six not grazed. There was no difference in perennial grass cover on the summer-grazed and winter-grazed plots. Intensive seasonal grazing had no effect on the abundance and community composition of soil microarthropods. Within each plot there were six subplots: summer rain-out, winter rain-out, burned, glucose amendment, rainout control and burn-glucose control. Fire and carbon enrichment had no significant effect on soil microarthropod abundance or community composition. The average number of microarthropods ranged from 8915 {\textpm} 1422 m-2 in the ungrazed, unburned plots to 7175 {\textpm} 1232 m-2 in the winter-grazed, unburned plots. Microarthropod densities in the glucose-amended plots were 8917 {\textpm} 4902 m-2 in the winter-grazed plots and 10,731 {\textpm} 863 m-2 in the glucose-amended, summer-grazed subplots. The prostigamatid mite, Tydeus sp., was the most abundant microarthropod taxon in all treatment plots. {\textcopyright} 2012 Elsevier Ltd. All rights reserved

}, keywords = {carbon enrichment, cattle, drought, fire, perennial grass cover, prostigmatid mite, rain-out shelter, soil microarthropods}, doi = {10.1016/j.jaridenv.2012.03.021}, url = {/files/bibliography/12-017.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @conference {JRN54589, title = {An empirical assessment of non-equilibrium theory and state-and-transition models with a long-term (1953-2009) vegetation record from the Sonoran Desert}, booktitle = {96th Ecological Society of America Annual Meeting}, year = {2011}, month = {08/2011}, publisher = {Ecological Society of America}, organization = {Ecological Society of America}, address = {Austin, Texas}, abstract = {Resilience-based ecological frameworks, including state-and-transition models (STM), are being increasingly called upon to guide ecosystem management and inform natural resource policy. Yet multiple challenges continue to impede their application, including limited empirical assessments of non-equilibrium theory, infrequent evaluation of expert-based STMs against long-term empirical data, and uncertainty in identifying early-warning signals of pending thresholds. We evaluated long-term term (1953-2009) vegetation data from the Sonoran Desert to address how well the inherent empirical trends are captured by the theoretical constructs of non-equilibrium theory and STMs. Seven statistically distinct plant communities were identified using model-based clustering and all instances of abrupt compositional transitions among communities were recorded. The temporal dynamics of species composition illustrate four major patterns {\textendash} high stability, random drift, reversibility, and irreversible change that corroborate the occurrence of both equilibrium and non-equilibrium dynamics in this system. Degree of compositional change during transitions was positively skewed indicating that even modest amounts of turnover could result in transitions. Transitions were more frequent between communities with similar species pools than between more distant communities. Frequency of transitions and the degree of spatial correlation in vegetation composition were both positively correlated with fluctuations in mean annual precipitation, with the greatest number of transitions occurring during wet periods. This provides new insights into the spatio-temporal dimension of ecological resilience, and aligns with the hypothesis that spatial correlation can serve as an early-warning signal of imminent thresholds, which can, at least in part, be linked to climatic drivers. The vegetation dynamics observed in this record indicate that conventional expressions of resilience and transitions in STMs may account for only a fraction of the complex dynamics that exist in ecosystems. A network of sites with long-term empirical data may provide ecological benchmarks to support emerging resilience-based management by guiding development of rules for model construction and corroborating the assumptions of existing STMs.}, author = {Bagchi, Sumanta and D.D. Briske and Wu, X.B. and M.P. McClaran and Brandon T Bestelmeyer and Maria Fern{\'a}ndez-Gim{\'e}nez} } @article {49944, title = {The ecology of dust}, journal = {Frontiers in Ecology and the Environment}, volume = {8}, year = {2011}, pages = {423-430}, abstract = {Wind erosion and associated dust emissions play a fundamental role in many ecological processes and provide important biogeochemical connectivity at scales ranging from individual plants up to the entire globe. Yet, most ecological studies do not explicitly consider dust-driven processes, perhaps because most relevant research on aeolian (wind-driven) processes has been presented in a geosciences rather than an ecological context. To bridge this disciplinary gap, we provide a general overview of the ecological importance of dust, examine complex interactions between wind erosion and ecosystem dynamics from the scale of plants and surrounding space to regional and global scales, and highlight specific examples of how disturbance affects these interactions and their consequences. It is likely that changes in climate and intensification of land use will lead to increased dust production from many drylands. To address these issues, environmental scientists, land managers, and policy makers need to consider wind erosion and dust emissions more explicitly in resource management decisions.}, keywords = {aeolian processes, biogeochemistry, climate change, disturbance, drylands, dust, dust emissions, dust flux, ecological processes, ecosystem dynamics, land use, resource management, wind erosion}, doi = {10.1890/090050}, author = {J. P. Field and Jayne Belnap and David D. Breshears and J. Neff and Gregory S. Okin and J. J. Whicker and Painter, T. H. and S. Ravi and Reheis, M. C. and Reynolds, R. L.} } @article {49961, title = {Endophyte Microbiome Diversity in Micropropagated Atriplex canescens and Atriplex torreyi var griffithsii}, journal = {PLoS ONE}, volume = {6}, year = {2011}, chapter = {e17693}, abstract = {Microbial diversity associated with micropropagated Atriplex species was assessed using microscopy, isolate culturing, and sequencing. Light, electron, and confocal microscopy revealed microbial cells in aseptically regenerated leaves and roots. Clone libraries and tag-encoded FLX amplicon pyrosequencing (TEFAP) analysis amplified sequences from callus homologous to diverse fungal and bacterial taxa. Culturing isolated some seed borne endophyte taxa which could be readily propagated apart from the host. Microbial cells were observed within biofilm-like residues associated with plant cell surfaces and intercellular spaces. Various universal primers amplified both plant and microbial sequences, with different primers revealing different patterns of fungal diversity. Bacterial and fungal TEFAP followed by alignment with sequences from curated databases revealed 7 bacterial and 17 ascomycete taxa in A. canescens, and 5 bacterial taxa in A. torreyi. Additional diversity was observed among isolates and clone libraries. Micropropagated Atriplex retains a complex, intimately associated microbiome which includes diverse strains well poised to interact in manners that influence host physiology. Microbiome analysis was facilitated by high throughput sequencing methods, but primer biases continue to limit recovery of diverse sequences from even moderately complex communities.}, doi = {doi:10.1371/journal.pone.0017693}, url = {/files/bibliography/11-004.pdf}, author = {M.E. Lucero and Unc, Adrian and Cooke, Peter and Dowd, Scot and Sun, Shulei} } @proceedings {49962, title = {Examining endophyte interactions within fourwing saltbush (Atriplex canescens)}, volume = {XVI}, year = {2011}, month = {06/2011}, pages = {159-164}, publisher = {The Berkeley Electronic Press}, address = {Bozeman, Montana}, abstract = {Cryptic endophyte consortia associated with embryonic tissues of fourwing saltbush (Atriplex canescens) are believed to serve mutualistic functions. However, the complexity of these endophyte communities makes cause-and-effect relationships difficult to establish. In fourwing saltbush, cryptic endophytes are thought to enhance drought and salt tolerance, nutrient acquisition, germination, and establishment. Some of these traits can be conferred to alternate host plants by co-culturing seedlings in vitro with micropropagated fourwing saltbush callus. Here we describe an evolving process for; 1) identifying arrays of cryptic, seed borne endophytes associated with fourwing saltbush; 2) evaluating early vigor of grasses and other plants endowed with fourwing saltbush endophytes; 3) selecting plant-endophyte combinations with increased tolerance to abiotic stressors, and 4) monitoring the persistance of transferred endophytes across plant generations in increasingly complex habitats. This process is designed to evaluate specific plant-fungal interactions that influence host tolerance to salinity, but may be broadly adaptable for selecting endophyte-enhanced plant germplasms with a variety of desired traits.}, keywords = {Atriplex canescens, browsing, cryptic endophyte consortia, embryonic, fire, herbivory, monitoring, proceedings, sagebrush, wildland shrubs}, url = {/files/bibliography/08-056.pdf}, author = {M.E. Lucero and J.R. Barrow and I. Reyes-Vera and Ruth L. Sedillo} } @inbook {49966, title = {Entisols}, booktitle = {Handbook of Soil Science}, year = {2011}, publisher = {CRC Press}, organization = {CRC Press}, edition = {2nd}, address = {Boca Raton}, keywords = {entisols, soil classification}, author = {Nordt, L. and Collins, M. E. and Fanning, D. S. and Curtis H. Monger} } @article {49994, title = {Experiences in monitoring and assessment of sustainable land management}, journal = {Land Degradation and Development}, volume = {22}, year = {2011}, month = {04/2011}, pages = {214-225}, chapter = {214}, abstract = {

Although sustainable land management (SLM) is widely promoted to prevent and mitigate land degradation and desertification, its monitoring and assessment (M\&A) has received much less attention. This paper compiles methodological approaches which to date have been little reported in the literature. It draws lessons from these experiences and identifies common elements and future pathways as a basis for a global approach. The paper starts with local level methods where the World Overview of Conservation Approaches and Technologies (WOCAT) framework catalogues SLM case studies. This tool has been included in the local level assessment of Land Degradation Assessment in Drylands (LADA) and in the EU-DESIRE project. Complementary site-based approaches can enhance an ecological process-based understanding of SLM variation. At national and sub-national levels, a joint WOCAT/LADA/DESIRE spatial assessment based on land use systems identifies the status and trends of degradation and SLM, including causes, drivers and impacts on ecosystem services. Expert consultation is combined with scientific evidence and enhanced where necessary with secondary data and indicator databases. At the global level, the Global Environment Facility (GEF) knowledge from the land (KM:Land) initiative uses indicators to demonstrate impacts of SLM investments. Key lessons learnt include the need for a multi-scale approach, making use of common indicators and a variety of information sources, including scientific data and local knowledge through participatory methods. Methodological consistencies allow cross-scale analyses, and findings are analysed and documented for use by decision-makers at various levels. Effective M\&A of SLM [e.g. for United Nations Convention to Combat Desertification (UNCCD)] requires a comprehensive methodological framework agreed by the major players.

}, keywords = {desertification, impact assessment, methodological framework, monitoring, multiple scales, participatory approaches, sustainable land management}, doi = {10.1002/ldr.1040}, url = {/files/bibliography/11-039.pdf}, author = {Schwilch, G. and Brandon T Bestelmeyer and Bunning, S. and Critchley, W. and Jeffrey E. Herrick and Kellner, K. and H. Liniger and Nachtergaele, F. and Ritsema, C. J. and Schuster, B. and Tabo, R. and Van Lynden, G. and Winslow, M.} } @article {50002, title = {Effects of simulated storm sizes and nitrogen on three Chihuahuan Desert perennial herbs and a grass}, journal = {Journal of Arid Environments}, volume = {75}, year = {2011}, month = {09/2011}, pages = {861-864}, chapter = {861}, abstract = {Establishment and growth of three perennial herbs and a small tussock grass were studied in an experiment that provided simulated rainfall of 6 mm week_1 or 25 mm once per month and nitrogen fertilization in combination with the different simulated rainfall regimes. Wild onion, Allium macropetalum, failed to establish in plots receiving 25 mm month_1 simulated rainfall. The perennial composite, Bahia absinthifolia, occurred at higher densities in plots that were not irrigated but there were no differences in biomass in any of the irrigation or fertilization treatments. Desert holly, Perezia nana, failed to establish in nitrogen fertilized plots and developed higher abundance and biomass in plots receiving 25 mm month_1. Nitrogen fertilization had either no effect or an adverse effect on the perennial herbs. The tussock grass, Dasychloa pulchella exhibited highest abundance and biomass with 6 mm week_1 added water plus nitrogen. Since global climate change will affect both rain storm frequency and size and atmospheric nitrogen deposition, the results of this study are applicable to understanding vegetation responses climate change.}, keywords = {abundance, biomass, fertilization, irrigation}, doi = {10.1016/j.jaridenv.2011.03.007}, url = {/files/bibliography/11-010.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @article {50029, title = {Essays of a Peripheral Mind: Invasions of the landscape snatchers}, journal = {Rangelands}, volume = {32}, number = {1}, year = {2010}, note = {Trade Journal}, pages = {52}, abstract = {Literally thousands of species have invaded the North American continent over recent centuries/millennia. Some, like creosote bush, have been here so long we do not even think of them as exotic. Others, like Kentucky bluegrass, pheasants and wine grapes are so imbedded in our native or cultivated landscapes that they are regarded as naturalized. In fact, the collapse of one, the honey bee, has created real concern and caused considerable resources to be mobilized in an effort to recover this exotic species. Some, like hemp, that were brought here for certain purposes have taken on different dimensions and create a certain madness that won{\textquoteright}t recede until we view them in a more mature and balanced light. One, the variola virus that causes small pox, has been eradicated in response to a globally organized effort. Some are relatively benign. At this time only a few dominate our thinking and our energies. In reality, one of the values of governments and government-sponsored research is the ability to coordinate and mobilize efforts across political boundaries. Our capacities today to contend with the real threats of exotic origins, like new viruses, the Asian citrus psyllid sweeping into the southern U.S., and the round goby threatening the Great Lakes, require this blending of scientific, management and policy strategies and tactics across our artificial boundaries which don{\textquoteright}t constrain these species. Without this coordination these species introductions, which a time line of invasion history teaches us are inevitable in many regards, can have severe and unacceptable impacts beyond our capacities to either mitigate or adapt.}, url = {/files/bibliography/09-032.pdf}, author = {Kris Havstad} } @article {50030, title = {Essays of a peripheral mind: Wyatt Earp, T.rex, and other dinosaurs}, journal = {Rangelands}, volume = {31}, number = {5}, year = {2010}, note = {Trade Journal}, pages = {39-40}, abstract = {There are many examples of science reforming and expanding and building on what we know in a fashion very different from what we had previously learned. The scientific method is doing exactly what it is supposed to do. We always start research from an incomplete understanding, so we interpret based on what we now know, hypothesize, and experiment. In other words, we accept the fact that we continue to learn. This is the basic adaptation in adaptively managing our resources and ourselves. There is a article published in 1996 (Rangeland Journal 18: 351-369) by the Australian scientists Watson, Burnside and Holm that addressed the issue of how science relates to the needs of natural resource managers. They discussed how scientific measurements and hypotheses should be used to support beliefs and local knowledge. They state that all knowledge is provisional, meaning that what we learn from science, from measurements and inductive logic, is provisional. That point is only partially correct. What they should really state is that all knowledge, including local knowledge and personal observations as well as science based measurement is provisional. In an effort to defend what we believe, we often resort to a tactic of pitting the art of observation against science, where we attempt to place a greater value on one form of knowledge vs another. What experience has taught us is that adaptive management in any field, including management of natural resources, is about learning and re-evaluating all forms of observation and knowledge. We need to convey to the public not only our subjective observations, but also our hypotheses and our related measurements. Both subjective local knowledge and science based knowledge are subject to incompleteness, misinterpretation, and/or inaccuracies.}, url = {/files/bibliography/09-031.pdf}, author = {Kris Havstad} } @inbook {50048, title = {Examination of seed-borne endophyte microbiomes}, booktitle = {Prospects and Applications fo Plant-Associated Microbes. A Laboratory Manual Part B: Fungi}, year = {2010}, chapter = {Examination of seed-borne endophyte microbiome}, abstract = {Plant microbiomes include numerous seed associated microbes which are vertically transferred to progeny. These complex microbial communities have not been heavily reported in scientific literature, possibly because they are difficult to detect and monitor. Yet potential for seed borne microbes to influence host plant performance across generations suggests opportunity for exploiting microbes to enhance host plant adaptation across changing habitats. The chenopod species Atriplex canescens offers a valuable model system in which to correlate the distribution of endophtye microbiomes with plant adaptation to stressed habitats. Broadly distributed across arid and saline habitats, the species is known for its restoration potential, complex genetics, and diverse microbial associations. The species lends itself well to micropropagation, and numerous fungal and bacterial species have been observed in micropropagated lines initiated from disinfested seeds. Hence, these micropropagated lines provide useful systems through which interactions between seed borne microbes and the plant itself can be systematically examined to improve understanding of microbial contributions to plant fitness. The shift from investigating plants as single entities to observing plants as lichenous consortia of mutualistic symbionts promises to expose opportunities for utilizing microbes to maximize plant productivity relative to human agricultural, biofuel, or restoration needs.}, author = {M.E. Lucero} } @article {50050, title = {Ecological site development: A gentle introduction}, journal = {Rangelands}, volume = {32}, year = {2010}, month = {12/2010}, pages = {16-22}, chapter = {16}, abstract = {Developing ecological sites requires knowledge of plant community dynamics and species interactions, as well as interactions between plants and soil properties, climate, and landscape features. Developers must know what questions to ask at the beginning of the development process, the data to collect in the field, and how to use the data to create and test ecological site concepts. Ecological sites are meant to provide a general ecological foundation for management. Ecological sites bring together several ecological concepts, including plant-soil interactions, succession and climax, non-equilibrium in community structure, and ecological gradients and spatial heterogeneity.\  Ecological sites integrate a variety of information sources, including inventory data that link plant communities to soil profiles and landscape position, historical reconstructions, and management considerations based on local knowledge and monitoring data. A well-organized plan is essential to properly develop a set of ecological sites. The steps in such a plan discussed here include (1) asking a set of general questions regarding ecological sites, (2) literature research and field visits for reconnaissance, (3) specification of initial ecological site concepts, (4) inventory data collection, (5) analysis and interpretation of data collected, and finally (6) refinement of ecological site concepts and the compilation of associated information into ecological site descriptions.}, url = {/files/bibliography/10-040.pdf}, author = {Moseley, Kendra and P. L. Shaver and H. Sanchez and Brandon T Bestelmeyer} } @conference {50079, title = {Ecological site descriptions as a management tool: Results of an SRM workshop}, booktitle = {62nd Society for Range Management Annual Meeting}, year = {2009}, month = {02/2009}, pages = {1000-14}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Albuquerque, NM}, abstract = {

The Society for Range Management (SRM) sponsored a workshop in Park City, UT 23-25 October 2007. The workshop was designed to 1) provide attendees with basic information on the concepts and applications of Ecological Site Descriptions (ESDs) 2) explore opportunities to improve applications of ESDs to the management of fish and wildlife habitat, specifically greater sage grouse and 3) seek input on additional information and reorganization of ESDs to improve utility. The workshop organization consisted of a full day of introductory remarks from experts, a day of facilitated group discussion divided into geographic regions, one-half day of summary and synthesis and a one-half day field trip. Approximately 300 people attended the workshop. Recommendations from the group identified several important considerations for future ESD development: more flexibility in the description of vegetation attributes (patch structure), an increased emphasis on vertical vegetation structure, increased discussion of the landscape scale arrangement of habitat elements (states). In addition, the groups desired to see the ESD development process expanded to include a wider variety of expertise and stakeholders and a greater emphasis on standardization across soil survey, state and regional boundaries. The SRM ESD workshop was widely considered a success and provides a basis for the continued expansion of outreach via technically oriented regional workshops.

}, keywords = {abstract, ecological site descriptions, ESDs, SRM}, author = {Joel R. Brown and Gilgert, W. and T.A. Messmer and M. Brunson and J. Maestas} } @article {50102, title = {Essays of a peripheral mind: Picking up rocks}, journal = {Rangelands}, volume = {31}, number = {2}, year = {2009}, month = {04/2009}, pages = {36-39}, chapter = {36}, abstract = {

In 2008 the Heinz Center released its report \“The State of the Nation\’s Ecosystems, 2008.\”\  The current report provides sets of assessments on the status of the nation\’s rangelands an area of approximately 1 billion acres.\  Unfortunately, on numerous occasions the report contains the phase \“Data Gap-data are not available for national reporting of an indicator.\”\  The Heinz Center attempts to employ 14 indicators to provide a national assessment of rangelands within one of the four categories of 1) extent and pattern of ecosystem area and land use, 2) chemical and physical characteristics, 3) biological components, and 4) goods and services\  Indicators are defined as specific, well-defined, and measureable variables that reflect key characteristics that can be tracked through time.\  The Heinz report likens indicators to human vital signs, such as blood pressure or cholesterol levels.\  Though indicators do not reflect the drivers behind the health of these rangelands, they can convey important characteristics of overall system health.\  This essay addresses the need to fill these data gaps.\  Without addressing these data gaps, we can not correct problems that limit the goods and serves that can be sustainably harvested from our nation\’s rangelands.

}, keywords = {Heinz, peripheral, rocks, Trade journal}, url = {/files/bibliography/09-013.pdf}, author = {Kris Havstad} } @conference {50110, title = {The effect of heterogeneous landscape dynamics on ecotone types at two convergent semi-arid biomes}, booktitle = {LTER All Scientist Meeting}, year = {2009}, month = {09/2009}, address = {Estes Park, Colorado}, abstract = {Landscapes in biome transition zones consist of a mosaic of patches dominated or codominated by species from adjacent biomes. Shifts in the vegetation composition and dynamics of a biome transition zone depend upon the underlying patch dynamics of the ecotones between these dominant species. Landscapes can consist of a number of different types of ecotones (directional, shifting, stationary) hypothesized to differ in the strength of three major factors: abiotic drivers, biotic feedbacks, and abiotic feedbacks. In this poster, our objective was to test the hypothesis that vegetation patterns across stationary ecotones are strongly related to abiotic factors that influence water availability (soil texture, microtopography) where weak correlations were expected for shifting ecotones. We tested this hypothesis for landscapes at the Sevilleta LTER site in central New Mexico, USA. Landscapes at the Sevilleta consist of a mosaic of patches dominated or codominated by three species: two perennial C4 grasses, Bouteloua gracilis (blue grama) and Bouteloua eriopoda (black grama), and one C3 shrub, Larrea tridentata (creosotebush). We estimated cover by species, analyzed soil samples (0-20cm), and obtained elevation using a Total Positioning Station every 5-10m along multiple transects for 10 ecotones. Our results show that stationary ecotones occur on finer-textured soils at slightly lower elevations (cms) compared with shifting ecotones. Soils and elevation were not good predictors of the location of shifting ecotones. Our results suggest that landscape dynamics at a biome transition zone depend on the factors controlling different types of ecotones. Even though the same species may be involved, the underlying processes determining ecotone dynamics may vary for different parts of the landscape.}, keywords = {biomes, mosaic, transition}, author = {Jeremy R. Klass and Debra C. Peters} } @conference {50115, title = {EcoTrends: Learning how to support synthetic research through innovative solutions}, booktitle = {LTER All Scientists Meeting}, year = {2009}, month = {09/11/2009}, address = {Estes Park, Colorado}, abstract = {The EcoTrends project is an LTER network-level synthesis program geared toward making long-term ecological data highly explorable, accessible and comparable for cross-site synthesis research. Five years of working with 50 sites (LTER, USDA ARS, USFS, and other agencies) have offered many lessons that can be utilized as we strive to improve and upgrade EcoTrends services. Here, we describe the project{\textquoteright}s goals and products, discuss lessons learned, and lay out plans for a future system that will better serve the ecological research and information management community.}, keywords = {cross-site, EcoTrends, LTER}, author = {C. Laney and Debra C. Peters} } @article {50116, title = {Effects of enhanced wind erosion on surface soil texture and characteristics of windblown sediments}, journal = {Journal of Geophysical Research - Biogeosciences}, volume = {114, G02003}, year = {2009}, chapter = {8 pp}, abstract = {

It is well documented that wind redistributes and transports soil resources in semiarid ecosystems. However, fewer studies have quantitatively linked wind erosion to detailed grain-size fractions and associated nutrient content in surface soil and windblown sediment. In this study, we examined (1) the effects of enhanced wind erosion on surface soil particle-size distribution and (2) carbon (C) and nitrogen (N) characteristics of windblown sediments in a typical desert grassland of southern New Mexico. Our results show that surface soil has become noticeably coarser over a 2-year period. In particular, content of soil particles in the category of 250{\textendash}500 ?m increased significantly, but soil particles in the fractions of 50{\textendash}125 {\textmu}m and \<50 {\textmu}m were significantly depleted. In addition to the enrichment of C and N in the windblown sediments, our results reveal that fine particles (e.g., D \< 50 {\textmu}m) were enriched to a much higher degree at height than C and N. Significantly, our results reveal that nearly 12\% of total organic carbon (TOC) and 9\% of total nitrogen (TN) were found in the particles with diameter \<50 {\textmu}m, which account for only 1{\textendash}2\% of the mass of windblown sediments. In this wind susceptible environment, our findings suggest that (1) significant soil texture change (e.g., the loss of soil fines) driven by wind erosion could happen rapidly and soil fine particles (e.g., silt and clay) may be depleted within a few years and (2) the loss of even a small fraction of fine particles may indicate a substantial depletion of soil C and N.

}, keywords = {aeolian processes, surface soil texture, wind erosion, windblown sediment}, doi = {10.1029/2008JG000903}, url = {files/bibliography/JRN00526.pdf}, author = {Junran Li and Gregory S. Okin and Howard Epstein} } @conference {50142, title = {Exploring the linkages between socio-economic \& ecological processes in rangeland landscapes}, booktitle = {62nd Society for Range Management Annual Meeting}, year = {2009}, month = {February 8-12, 2}, pages = {30-2}, publisher = {Society for Range Mangement}, organization = {Society for Range Mangement}, address = {Alb., NM}, abstract = {Ecological and socio-economic processes are driving land-use and land-cover change (LULCC) on many of the world{\textquoteright}s rangelands, but we have a poor understanding of the mechanisms by which these processes are linked to each other. This is largely because data for socio-economic and ecological factors are usually expressed at distinct (and multiple) scales, and because of a lack of data on region-scale patterns. It is widely held that human behaviors underlie LULCC tipping points, but we have little systematic understanding of how variations in behavior affect them. In the U.S., for example, spatial patterns of control of public grazing lands established under the Taylor Grazing Act, the adoption of more stringent rangeland oversight policies (e.g., the National Environmental Policy Act), goals, motivations, and objectives of ranch operators as well as the constraints under which ranchers operate may have large and unrecognized impacts on the occurrence of LULCC. We are conducting research that is overcoming scale mis-matches to link socio-economic and ecological processes to explain southwestern U.S. public rangeland LULCC with unprecedented detail. The objective of this research is to develop a framework for linking socio-economic and ecological data at landscape to regional scales in order to explain past rangeland LULCC and forecast future changes. This paper reports on this research in its early stages and presents preliminary results of the research.}, keywords = {abstract, ecological, land-use and land-cover change, LULCC, socio-economic, SRM}, author = {R. K. Skaggs and Brandon T Bestelmeyer} } @article {JRN54973, title = {An empirical study on the utility of BRDF model parameters and topographic parameters for mapping vegetation in a semi-arid region with MISR imagery}, journal = {International Journal of Remote Sensing}, volume = {30}, year = {2009}, month = {07/2009}, pages = {3463-3483}, chapter = {3463}, abstract = {

In this study we show that multiangle remote sensing is useful for increasing the accuracy of vegetation community type mapping in desert regions. Using images from the National Aeronautics and Space Administration (NASA) Multiangle Imaging Spectroradiometer (MISR), we compared roles played by Bidirectional Reflectance Distribution Function (BRDF) model parameters with those played
by topographic parameters in improving vegetation community type classifications for the Jornada Experimental Range and the Sevilleta National Wildlife Refuge in New Mexico, USA. The BRDF models used were the Rahman{\textendash}Pinty{\textendash}Verstraete (RPV) model and the RossThin-LiSparseReciprocal (RTnLS) model. MISR nadir multispectral reflectance was considered as baseline because nadir
observation is the most basic remote sensing observation. The BRDF model parameters and the topographic parameters were considered as additional data. The BRDF model parameters were obtained by inversion of the RPV model and the RTnLS model against the MISR multiangle reflectance data. The results of 32 classification experiments show that the BRDF model parameters are useful for vegetation mapping; they can be used to raise classification accuracies by providing information that is not available in the spectral-nadir domain, or from ancillary topographic parameters. This study suggests that the Moderate Resolution Imaging Spectroradiometer (MODIS) and MISR BRDF model parameter data products have great potential to be used as additional information
for vegetation mapping.

}, url = {files/bibliography/Rango2009-01.pdf}, author = {L. Su and Y. Huang and M. Chopping and A. Rango and J. V. Martonchik} } @article {50145, title = {An empirical study on the utility of BRDF model parameters and topographic parameters for mapping vegetation in a semi-arid region with MISR imagery}, journal = {International Journal of Remote Sensing}, volume = {30}, number = {13}, year = {2009}, month = {09/2009}, pages = {3463-3483}, abstract = {

Multi-angle remote sensing has been proved useful for mapping vegetation community types in desert regions. Based on Multi-angle Imaging Spectro-Radiometer (MISR) multi-angular images, this study compares roles played by Bidirectional Reflectance Distribution Function (BRDF) model parameters with those played by topographic parameters in improving vegetation community type classification at the Jornada Experimental Range and the Sevilleta National Wildlife Refuge in New Mexico, U.S.A. The BRDF models used are the Rahman-Pinty-Verstraete model and the RossThin-LiSparseReciporal model. MISR nadir multi-spectral reflectance is considered as baseline because nadir observation is the most basic remote sensing observation. The BRDF model parameters and the topographic parameters are considered as additional data. The BRDF model parameters are obtained via inversion of the Rahman-Pinty-Verstraete model and RossThin-LiSparseReciporal model against the MISR multi-angle reflectance. The topographic parameters are derived from Digital Elevation Models of the Jornada and the Sevilleta. In order to confirm whether increased accuracy is from additional data, two classifiers, Maximum Likelihood Classification algorithm and Support Vector Machine algorithm, are used in this research. In total, 32 classification experiments were carried out by the two classifiers on 16 datasets, which were formed by various combinations of the MISR nadir multi-spectral reflectance, the BRDF model parameters and the topographic parameters. These experiments show the following findings: 1) both the topologic parameters and the BRDF parameters can provide meaningful additional information for this semi-arid vegetation mapping; and 2) in the case of a semi-arid environment, the BRDF parameters are slightly more efficient than the topologic parameters. This study suggests that the MISR BRDF model parameter products have great potential to be used as additional information for vegetation mapping.

}, keywords = {BRDF, empirical, imagaery, MISR, remote sensing}, doi = {10.1080/01431160802562230}, url = {/files/bibliography/09-023.pdf}, author = {L. Su and Y. Huang and M. Chopping and A. Rango and J. V. Martochik} } @conference {50156, title = {Enhancing knowledge of rangeland ecological processes with benchmark ecological sites}, booktitle = {62nd Society for Range Management Annual Meeting}, year = {2009}, month = {February 8-12, 2}, pages = {1000-20}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Albuquerque, NM}, abstract = {A benchmark ecological site is one that has the greatest potential to yield data and information about ecological functions, processes, and the effects of management or climate changes on a broad area or critical ecological zone. A benchmark ecological site represents other similar sites in a major land resource area. Information gathered about benchmark ecological sites can address many different ecological, social, and resource management issues. One of the purposes of designating benchmark ecological sites is to promote greater understanding of the potential effects of management, natural disturbance, and climate change on rangeland ecosystem dynamics and soils. This will allow land managers to use adaptive management to provide for sustainability of natural resources on these landscapes. Examples of resource issues that could be addressed include the effects of management actions, disturbance, and climate change on livestock management; threatened, endangered, and other plant and animal species of concern; spread of invasive species; soil erosion, sedimentation, and runoff; soil ecology; plant community composition and productivity; and habitat reclamation potential.}, keywords = {abstract, benchmark, ecological, ecological site, management}, author = {W. G. Ypilantis and Michael S. Karl and Bottomley, T. and Biggam, P. and A. O{\textquoteright}Green and Curtis Talbot and Townsend, L. and Brandon T Bestelmeyer and Davis, R.} } @article {50204, title = {Effects of cis-beta-sabinene hydrate, and monoterpene adn sesquiterpene mixtures on alfalfa pellet intake by lambs}, journal = {Journal of Animal Science}, volume = {86}, year = {2008}, month = {June 2008}, pages = {1478-1484}, abstract = {

The transition of grasslands to shrub-dominated scrubland reduces livestock productivity and contributes to impoverished human conditions in arid and semiarid regions worldwide. Many shrubs increasing in dominance contain secondary compounds that deter herbivores. Knowledge concerning the effects of specific compounds on herbivore diets is limited but may provide useful insights into desertification. Flourensia cernua is a dominant shrub in the northern Chihuahuan Desert that contains an abundance of terpenes. Four experiments were conducted to determine the effects of individual terpenes (cis-\â-ocimene and cis-sabinene hydrate; Exp. 1 and 2) or mixtures of monoterpenes (borneol, camphene, camphor, 1,8-cineole, limonene, myrcene, and \á-pinene; Exp. 3) or sesquiterpenes (\â-caryophyllene, caryophyllene oxide, \á-copaene, and \á-humulene; Exp. 4) on intake of alfalfa pellets by lambs. Forty-five lambs (9 lambs/treatment) were individually fed treated alfalfa pellets for 20 min each morning for 5 days. Five treatments (0X, .5X, 1X, 2X, and 10X; multiples of the concentrations of the same terpenes in Flourensia cernua) were applied to alfalfa pellets (637 g, DM basis) in an ethanol carrier. Experiments were preceded by a 10-d adaptation period to untreated pellets. Except during the 20-min test, lambs were maintained outdoors and fed untreated alfalfa pellets (total mean intake = 4.7\% of BW, DM basis). Day \× treatment interactions were detected (P\< 0.04) in Exp. 1 and 4, due to greater intake for 0X than other treatments on day 1 (Exp. 1) and lower intake for the 10X treatment on day 1 and 2 (Exp. 4). A trend for decreased intake (g/kg BW) as concentration of the sesquiterpene mixture increased was observed in Exp. 3 (P = 0.093 for the linear contrast). Although there was a tendency for the sesquiterpene mixture to decrease intake, cis-\â-ocimene, cis-sabinene hydrate, and the monoterpene mixture did not appear to affect intake by lambs. Thus, sesquiterpenes may exert antiherbivory properties under certain conditions that may contribute to shrub dominance with extended periods of livestock foraging.

}, keywords = {alfalfa pellets, lambs, monoterpene, sesquiterpene}, doi = {10.2527/jas.2007-0699}, url = {/files/bibliography/08-009.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @article {50208, title = {Effects of harvester ant (Messor spp.) activity on soil properties and microbial communities in a Negev Desert ecosystem}, journal = {Biology and Fertility of Soils}, number = {45}, year = {2008}, month = {12/2008}, pages = {165-173}, chapter = {165}, abstract = {

Harvester ants (Messor spp.) function as an essential link between aboveground resources and belowground biota such as the microbial community. We examine changes in soil microbial biomass and functional diversity resulting from harvester ant (Messor spp.) activity in the Negev Desert, Israel. Abiotic and biotic soil parameters were recorded during two seasons {\textendash} wet and dry {\textendash} also representing food availability periods for the ants (low and high seed availability, respectively). Soil samples were collected monthly from the 0- to 10- and 10- to 20-cm soil layers: (1) near the nest entrance, (2) under chaff piles, and (3) at a 2-m radius from the nest entrance (control). Harvester ant activity increased the percentage of organic matter, total soluble nitrogen, and microbial activity in nest-modified soils in comparison to the control soils. Higher CO2 evolution was recorded in the low-seed season in ant nest soils than in the control soils. During the high-seed season, higher carbon dioxide evolution was recorded only at the nest entrance locations. There were no differences in microbial biomass between the low- and high-seed seasons, but highest microbial biomass was found under chaff in low-seed season and in nest soils in high-seed season. Microbial function diversity was higher in nest-modified soils than in the control soils. This study suggests that the effect of harvester ant nests on soil fertility is due to increased microbial biomass and microbial activity in ant nest-modified soils.

}, keywords = {ants, desert system, diversity, Harvester ants, microbial biomass, Negev Desert, soil moisture, soil organic mater}, doi = {10.1007/s00374-008-0309-z}, url = {/files/bibliography/08-042.pdf}, author = {O. Ginzburg and Walter G. Whitford and Yosef Steinberger} } @inbook {50218, title = {Ecosystem functions of grazing lands}, booktitle = {International Community Rangeland Mangement, People and Policy: Introducing Some Key Concepts}, year = {2008}, note = {Topic $\#$16}, month = {2008}, pages = {16}, publisher = {Ford Foundation Press}, organization = {Ford Foundation Press}, abstract = {

An ecosystem is a community of animals and plants interacting with one another and their physical environment. Rangeland ecosystems are the communities of organisms including humans, interacting with each other within environments characterized by herbaceous and/or shrubby vegetation common to arid and semi-arid regions around the world. These ecosystems occur within the grasslands of Asia, the deserts of North America, the savannas of Africa, the shrublands of Australia, the pampas of /South America, and in many other regions. Over 1 billion people live within these rangeland ecosystems. Though many goods and services from rangeland ecosystems are critically important to the 1 billion people living on or adjacent to rangeland, many of these services lack specific economic values. Few services are linked to an economic market that would create specific values, or incentives for conservation of their provisions to the public. Often values for services have been based on the known values of common goods, such as the value of rangeland for providing forage for grazing livestock. These economic values are often quite low because of the relatively low production capacities of the world\’s rangelands. However, markets for less traditional regulating services such as carbon sequestration, or cultural services such as recreation, are emerging. It will be critical that appropriate policies are implemented that provide appropriate incentives and benefits that will support the conservation of any ecosystem services as their economic values are more readily apparent and utilized.\  Irrespective of the specific arrays of goods and services provided from rangelands, a key service to rangelands will be the use of ecologically based practices to ensure their sustained resilience, or the capacity to reorganize and provide their characteristic functions, structures and feedbacks following disturbances.\  Rangelands are coupled systems of nature and humans, and proper management of these landscapes is critical to their continued supply of services and good that we request, recognized or not and appropriately valued or not.

}, keywords = {ecosystem, grazing, rangelands, shrubland}, author = {Kris Havstad} } @article {50221, title = {Essays of a peripheral mind: An opinion on policy}, journal = {Rangelands}, volume = {30}, number = {6}, year = {2008}, month = {12/2008}, pages = {42-44}, type = {Trade Journal}, chapter = {42}, keywords = {essays, grazing, opinion, peripheral, policy, Trade journal}, url = {/files/bibliography/08-044.pdf}, author = {Kris Havstad} } @article {50219, title = {Essays of a peripheral mind: Authentic frontier gibberish}, journal = {Rangelands}, volume = {30}, number = { 2}, year = {2008}, month = {April 2008}, abstract = {The most interesting and intriguing general hypotheses currently being tested within the rangeland science profession are hypotheses related to 1) threshold-resilience (i.e., models which attempt to more explicitly characterize rangeland dynamics through detailing coupled impacts of disturbance to both vegetation and soils), 2) scaling i.e., effects of disturbance which recognize that both time and space can have differential and confounding effects on system response to those disturbances), and 3) indicators (i.e., the detection of components of ecological properties that are related to key community or landscape processes that can be used in assessment and monitoring. The broad objectives of the above 3 mentioned general hypotheses are actually now new. For example, for decades we have tried to understand effects of livestock grazing at pasture, allotment and ranch scales, and have worked to develop techniques to assess and monitor rangelands. What is important about the newer hypotheses is that they reflect efforts to reinterpret the familiar, to continue to discover the hidden realities of these systems, to advance efforts to connect observations to explanations.}, keywords = {authentic, essays, frontier, gibberish, peripheral mind, trade}, url = {/files/bibliography/08-015.pdf}, author = {Kris Havstad} } @article {50220, title = {Essays of a peripheral mind: Creative destruction}, journal = {Rangelands}, number = {1}, year = {2008}, month = {02/01/2008}, pages = {29-32}, abstract = {Since the 1950s the population of the western US has grown by more than 46 million people, and is projected to grow by an additional 20 million or so by 2025. The increased stress on the region{\textquoteright}s natural resources, especially water (for recent descriptions of this stress see: http://www.npr.org/programs/atc/features/2003/aug/water/ or http://www.nytimes.com/2007/10/21/magazine/21water-t.html?_r=1\&oref=slogin), and the resulting impacts on these landscapes and its species, are well recognized. Yet, the extent to which this population increase has driven a transition of these regional rangelands from providing the classic provisioning services of food and fiber from livestock grazing to a much more diverse non agricultural set of goods and services is often not so readily grasped. The extent of this transition is driven home by an array of available statistics that reflect these changes (for a more complete description of rural transformations in America see the 2006 Carsey Institute Report at: http://www.carseyinstitute.unh.edu/documents/Demographics_complete_file.pdf). For example only 25\% of western US non metro counties (72 counties of 286) have a principal economic dependency on agriculture, a number that is strongly influenced by just one state {\textendash} Montana. Increasingly, these non metro areas are destinations for both recreation and retirement (over 47\% of these counties are either retirement or recreation destinations, or both). The western U.S. has shifted from a rural to a metro based population with rural economics dependent on non-agricultural enterprises. Sustainable use of the natural resources of the western U.S. will now need to reflect the goods and services demanded by a non-agricultural oriented population.}, keywords = {creative, destruction, essays, mind, peripheral, trade}, url = {/files/bibliography/08-016.pdf}, author = {Kris Havstad} } @article {50215, title = {Essays of a peripheral mind: Desperately creative acts}, journal = {Rangelands}, volume = {30}, number = {5}, year = {2008}, month = {October 1, 2008}, pages = {25-28}, abstract = {This article focuses on New Mexico rangelands and some of the more progressive resource management collaborations that are at home in the Land of Enchantment. These examples can be viewed as experiments, and they are experimental in a sense that they may still fail or reform in face of experience. These examples have several common threads, including people strongly linked to rangelands, often unusual or nontraditional alliances, and efforts often scrutinized, if not criticized. They represent collective risks, but risks seen as necessary to advance resource management beyond its current stasis. In fact, to some extent, these can be seen as acts of desperation, where some unseen threshold of necessity had been breached and the need for another management model was required. The people directly involved in these efforts may cringe, if not loudly object, to having their collaboration depicted as desperate. Yet, these creative acts each represent something other than the norm, and required considerable effort to emerge as viable resource management models against the norm. Each developed and emerged in a very different fashion. One came out of the political world, one came out of a chance encounter, and one came out of a rural community of people sitting down and talking. Obviously, experiments like these can precipitate out of many different reactants and crucibles.}, keywords = {essays, peripheral mind, resource management, trade}, url = {/files/bibliography/09-012.pdf}, author = {Kris Havstad} } @article {50216, title = {Essays of a peripheral mind: The range problem in New Mexico}, journal = {Rangelands}, volume = {30}, number = {3}, year = {2008}, month = {June 30, 2008}, pages = {56-58}, abstract = {This essay reviews the 1908 report on the condition of rangelands in New Mexico written by Elmer Ottis Wooton. The purpose of this review is to evaluate the central recommendation in that report which encouraged a federally based system of land resource management. The premise of this review is that this recommendation was inappropriate, and that management of lands that are strongly shaped by humans should be in the hands of those people living on these rangelands. The increasing frequency of locally-driven, community-based management groups in the western U.S. reflects the value of a non-federal system of management practices and applications.}, keywords = {essays, New Mexico, peripheral, range problem}, url = {/files/bibliography/08-018.pdf}, author = {Kris Havstad} } @article {50236, title = {Effects of wind erosion on the spatial heterogeneity of soil nutrients in two desert grassland communities}, journal = {Biogeochemistry}, volume = {88}, number = {1}, year = {2008}, note = {//USDA//LTER-V//entered 06/06/2008; PDF on file}, month = {2008}, pages = {73}, abstract = {

Wind is known to affect the spatial heterogeneity of soil resources in arid and semiarid systems, but multi-year, quantified observations are largely absent. We studied the effects of wind erosion on the spatial distribution of soil organic carbon (SOC) and other soil nutrients at the Jornada Experimental Range, in southern New Mexico. Enhanced wind erosion was encouraged by grass cover reduction in a Sporobolus-mesquite dominated site (SM) and a Bouteloua-mesquite dominated site (BM). The scale and magnitude of spatial dependence for the soil analytes were quantified using geostatistical analyses. Results of this study show that soil organic matter related analytes such as SOC, TN, Navail, and SO4 2 are among the first to be eroded and redistributed; cations such as Ca2+ and Mg2+ may not be removed and redistributed significantly; and other ions such as K+, Na+ and Cl- showed no discernible pattern of change. Geostatistics show that wind appeared to increase the scale of spatial autocorrelation, but decrease the scale of spatial dependence of most soil analytes over 2{\textendash}3 windy seasons. In the wind enhanced plot of the SM site, up to 99\% of the spatial dependence of SOC was autocorrelated at the distance of 1.45 m before the initiation of wind erosion, but the spatial dependence dropped significantly to only 60\% at a larger autocorrelation distance of 2.76 m after three windy seasons. Similar but less significant changes were observed for SOC in the BM site. Despite the differential effects of wind on the soil analytes, we conclude that the overall results of wind on the grass cover reduction plots are the disappearance of small, strong fertile islands, which may be related to grasses; and the reinforcement of large fertile islands, which are likely related to mesquite shrubs. In addition, the change of the spatial patterns of SOC and other soil nutrients induced by enhanced wind erosion may persist and reinforce soil islands associated with shrubs, thus allowing a positive feedback for further desertification in this arid grassland.

}, keywords = {article, geostatistics, journal, soil carbon, soil nitrogen, soil nutrients, spatial heterogeneity, wind erosion, soil carbon, wind erosion, soil nitrogen, wind erosion, soil nutrients}, doi = {10.1007/s10533-008-9195-6}, url = {files/bibliography/JRN00499.pdf}, author = {Junran Li and Gregory S. Okin and Lorelei Alvarez and Howard Epstein} } @article {50238, title = {Enhancing native grass productivity by cocultivating with endophyte-laden calli}, journal = {Rangeland Ecology and Management}, volume = {61}, year = {2008}, month = {January 2008}, pages = {124-130}, abstract = {The influence native endophytes have on grass establishment and productivity was evaluated by co-cultivating Bouteloua eriopoda (Torr.) Torr. (black grama) or Sporobolus cryptandrus (Torr.) Gray (sand dropseed) seedlings with endophyte-laden calli from three of four native grass and shrub species; Atriplex canescens (Pursh) Nutt. (fourwing saltbush), S. cryptandrus, S. airoides (Torr.) Torr. (alkali sacaton), and B. eriopoda in-vitro. Following co-cultivation, grass seedlings were hardened and transferred to 3 replicate field plots each containing 16 grass plants of a single species which had been co-cultivated with a single callus species. Plant establishment rates, heights, crown diameters, above ground biomass, seed yields, and seed quality were compared. In B. eriopoda (black grama), significant increases in plant biomass were not observed. However, early plant heights and crown diameters, establishment rates, and stolon production were higher in some callus treatments. In S. cryptandrus (sand dropseed), all variables were positively influenced by one or more of the endophyte treatments. Biomass increases ranged from 2.5 to 3-fold over untreated plants, and harvested seed increased 5.9-fold in plants treated with endophytes from A. canescens (fourwing saltbush). Seed quality, determined by purity, germination rates, and tetrazolium assays, and did not differ across endophyte treatments for either grass. There is evidence that endophyte transfer is responsible for the altered vigor of treated plants, but this conclusion requires further study.}, keywords = {Atriplex canescens, Bouteloua eriopoda, endophytes, native grasses, non-mycorrhizal, Sporobolus airoides, Sporobolus cryptandrus}, url = {/files/bibliography/08-004.pdf}, author = {M.E. Lucero and J.R. Barrow and P. Osuna and I. Reyes-Vera} } @article {50255, title = {Ecology in a connect world: A vision for a "network of networks"}, journal = {Frontiers in Ecology and the Environment}, volume = {6}, number = {5}, year = {2008}, month = {06/2008}, pages = {227}, abstract = {

This special issue addresses the importance of connectivity in driving ecosystem dynamics. Connectivity is defined as the transfer of materials by wind, water, humans, and animals. Although it is well-recognized that we live in a connected world, it is less well-appreciated that these interconnections can determine ecosystem dyamics across a range of spatial and temporal scales, and in particular at regional to continental scales. The six papers in this issue provide examples of research questions and approaches necessary for conducting research at the continental scale. These papers address questions such as: what are the consequences of connectivity, not only at the global scale, but also at relevant continental, regional, and local scales? how do we identify connections among non-adjacent and seemingly disconnected locations, to both minimize the element of surprise and mitigate or avert potential impacts? how do we adjust our thinking about ecological systems and modify our sampling strategies to account for the fluxes and flows of materials among locations? New insights are discussed for five topics (spread of invasive species and infectious diseases, climate change and aquatic systems, climate change and coastal systems, climatic and societal gradients across landscapes, climate change and terrestrial systems) that are critical elements of our connected world, now and in the future.

}, keywords = {ecosystem dynamics, fluxes}, url = {/files/bibliography/08-010.pdf}, author = {Debra C. Peters} } @mastersthesis {50271, title = {Experiments with methods for particle size analysis of gypsic soils}, year = {2008}, note = {//USDA//LTER V//entered 06/11/2009; added abstract 6/22/2009ProCite field[12]: Not in File (06/11/2009)}, month = {2008}, pages = {58}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, NM}, abstract = {Gypsum is a common mineral in many dryland soils throughout the world. Gypsic soils have unique properties that impact roads, foundations, metal and concrete. One challenging aspect of gypsic soils is determining the particle size distribution. Because of gypsum{\textquoteright}s softness (1.5-2.0 on the Mohs scale) gypsum particles can be broken by rolling pins and shakers. Because of its solubility (2.41 g/L), gypsum particles can be dissolved during sedimentation. This research effort explores ways to prevent gypsum dissolution, while conducting textural analysis by using low viscosity oil, NaCl solution, saturated gypsum solution, a combination of a saturated Na2SO4 and gypsum solution, a method with no clay sized gypsum, and finally, a filtration method where the sand and the silt is sieved in saturated gypsum solution. Although low viscosity oil prevented gypsum dissolution, it was unsuitable because of problems with the drying of the oil-saturated sample and cost. NaCl solution was unsuitable because it did not prevent gypsum dissolution as a result of ion pairing. Saturated gypsum solution prevented gypsum from dissolving because of the common ion effect; however, clay particles flocculated in the solution. The use of Na2SO4 and saturated gypsum solution was used to disperse these particles. However, with high concentrations of Na+ the clay particles still flocculated. The method based on the assumption that no gypsum exists in the clay fraction was proven inaccurate with scanning electron microscope (SEM). Finally, the filtration method, in which silt is collected on high flow glass fiber filter paper under vacuum, shows good results when compared to the standard pipette method.}, keywords = {dissertation, G-BASN, P-COLL, P-TOBO, technique, gypsic soils, technique, particle size analysis, technique, soil methods, thesis}, url = {NMSU Branson Library call $\#$: S 1999 .R3916 2008 c.2}, author = {Riggs, Justin} } @article {50282, title = {Ecosystem services and western U.S. rangelands}, volume = {23}, number = {2}, year = {2008}, note = {//OTHER//LTER V//entered 06/29/2009; pdf available}, month = {2008}, pages = {37-41}, publisher = {American Agricultural Economics Association}, abstract = {

Rangelands are expansive, unimproved lands located in arid or semi{\textendash}arid regions, spanning a variety of landscapes including savannahs, high and low altitude deserts, mountain meadows, and tundra. Rangelands are generally unsuitable for crop production due to aridity, topography, and extreme temperatures. Rangelands support varying mixtures of native and nonnative grasses, grass{\textendash}like plants, forbs, or shrubs which provide forage for free{\textendash}ranging native and domestic animals (Stoddart, Smith and Box, 1975). There are more than 760 million acres of rangelands in the United States, including Alaska, comprising 33\% of the nation{\textquoteright}s total land base (USDA{\textendash}USFS, 1989a). While exact determinations are unavailable, it is estimated that more than 50\% of U.S. rangelands are privately owned, 43\% are owned by the federal government, with the remainder owned by state and local governments (National Research Council, 1994). Approximately 262 million acres of U.S. rangelands are controlled by the U.S. Forest Service (USFS) and the U.S. Bureau of Land Management (BLM) and leased to private individuals for the purpose of land{\textendash}extensive livestock grazing (CAST, 1996). Many more acres of rangelands in the 11 western states are controlled by state or local government agencies and leased for livestock grazing,\  with all these states having a high degree of intermingled public and private ownership of rangelands.

}, keywords = {article, carbon credits, carbon sequestration, ecosystem services, magagine, rangeland}, url = {files/bibliography/JRN00497.pdf}, author = {R. K. Skaggs} } @conference {50292, title = {Effects of one-seed juniper and polyethylene glycol on intake, rumen fermentation, and plasma amino acids in sheep and goats fed supplemental protein and tannins.}, booktitle = {Journal of Animal Science}, volume = {86}, number = {(E-Supple. 2)}, year = {2008}, month = {July 7, 2008}, pages = {224}, abstract = {We tested the effect of polyethylene glycol (PEG) on juniper and total intake, rumen fermentation, and plasma amino acids (AA) of 12 does and 12 ewes fed sudangrass and basal diets containing 10\% quebracho tannins with no protein supplement (Control; 5\% CP) or high rumen degradable (RDP 15\% CP) or undegradable (RUP 15\% CP) protein supplement. After 15 days of exposure to non-restrictive amounts of juniper leaves, sudangrass, and basal diets (period 1), animals received an additional 50 g of PEG for a second 15-d period. Blood and ruminal fluid samples were collected on the last 2 d of each period to determine AA and VFA ({\textmu}M). Analyses followed a split-plot design with periods with or without PEG treated as a sub-plot factor. Juniper intake did not differ between species (P > 0.05) or supplements (P > 0.05), but increased with addition of PEG in period 2 (Period 1 vs. 2: 4.3 vs. 10.8 g/kg 0.75; P < 0.01). Total intake and intake of sudangrass and basal diets were higher for sheep than goats (P < 0.01) and differed between supplements and periods (supplement x period, P < 0.05). Polyethylene glycol stimulated higher intakes of basal diet for Control and RDP, and of sudangrass for RUP. Total VFA was higher for sheep than goats (P < 0.05) and decreased from period 1 to period 2 with supplemental PEG in sheep (70.6 vs. 62.1; species x period, P < 0.05) and with RDP (67.3 vs. 58.6; supplement x period, P < 0.05). Acetate and propionate differed between periods with or without PEG in the same manner as total VFA. Total AA and some individual AA differed between species (sheep > goats), supplements (RUP = RDP > Control), and periods (P < 0.05). Increased juniper intake with PEG in period 2 was associated with lower plasma GLY, THR, SER, ASP, MET, GLU, PHE, CYST, GLN, ORN, LYS, HIS, and TRP. Polyethylene glycol increased juniper intake and decreased several plasma AA when tannin-rich foods with varying CP were fed.}, keywords = {abstract, goats, one-seed juniper, polyethylene glycol, rumen, sheep}, author = {S. A. Utsumi and Andr{\'e}s F. Cibils and Richard E. Estell and S. Soto-Navarro and Hallford, D.M.} } @conference {50290, title = {Effects of one-seed juniper on intake, rumen fermentation, and plasma amino acids in sheep and goats fed supplemental protein}, booktitle = {Journal of Animal Science}, volume = {86}, number = {E-supple. 2}, year = {2008}, month = {July 7, 2008}, pages = {223}, abstract = {We tested the effect of feeding one-seed juniper on total intake, VFA profile, and plasma amino acids (AA) of 12 does and 12 ewes fed sudangrass and a basal diet with no protein supplement (Control; 5\% CP) or rumen degradable (SBM; RDP 15\% CP) or undegradable (FM; RUP 15\% CP) protein supplement. After 15 d of adaptation to sudangrass and basal diets (period 1), animals received one-seed juniper leaves in addition to sudangrass and basal diets during a second 15-d period. Each food was fed separately during 3-h periods at 10\% of previous day intake. Blood and ruminal fluid samples were collected on the last 2 d of each period to determine plasma AA, VFA ({\textmu}M), and rumen pH. Analyses followed a split-plot design with periods with or without juniper as a sub-plot factor. Juniper intake did not vary between species (P = 0.54) or supplement treatments (P = 0.93; 4.7 g/kg0.75). Total intake (TI), basal diet intake (BDI), and sudangrass intake (SGI) were unaffected by supplements, were higher for sheep than goats (P < 0.01), and decreased with juniper feeding in period 2 (P < 0.01). Total intake, BDI, and SGI for periods 1 and 2 were 54.9 vs. 47.6, 36.7 vs. 31.5, and 18.2 vs. 11.5 g/kg0.75, respectively. Total VFA, acetate (Ac), and propionate (Pr) increased with juniper in period 2 (P < 0.01; period 1 vs. 2, VFA: 63.9 vs. 79.4; Ac: 47.5 vs. 60.5; Pr: 9.3 vs. 11.7). Rumen pH averaged 6.4 and did not differ between supplements, species, or periods. Total AA and some individual AA differed between supplements (RUP = RDP > Control), species (goats > sheep), and decreased with juniper feeding in period 2 (P < 0.05). Juniper intake in period 2 was associated with decreased plasma ALA, GLY, THR, SER, ASP, MET, GLU, PHE, CYST, TYR, and TRP. These data suggest one-seed juniper in sheep and goat diets depresses intake, but may increase VFA and requirements for certain amino acids.}, keywords = {abstract, goats, juniper, one-seed, sheep}, author = {S. A. Utsumi and Andr{\'e}s F. Cibils and Richard E. Estell and S. Soto-Navarro and Hallford, D.M.} } @article {50302, title = {Effects of three species of Chihuahuan Desert ants on annual plants and soil properties}, journal = {Journal of Arid Environments}, volume = {72}, year = {2008}, month = {04/2008}, pages = {392-400}, chapter = {392}, abstract = {We tested the hypothesis that ant species, which occupy the same nest for a decade or longer, would modify nest soils by increasing soil nutrients and microorganisms resulting in increased biomass, density, cover and species richness of annual plants. We measured soil properties and annual plants on nest soils of three species of Chihuahuan Desert ants (Pogonomyrmex rugosus--seed harvester, Aphaenogaster cockerelli--generalist forager, and Myrmecocystus depilis--liquid collector-insect scavenger) in comparison to paired reference soils at several locations. There were no differences in nest and reference total soil nitrogen of M. depilis and of P. rugosus on three catena soils. Total soil nitrogen of nest-modified soils was higher than of reference soils of A. cockerelli and P. rugosus in a desert grassland site. Soil microbial biomass and respiration were not significantly different among ant species at most locations with the exception of P. rugosus at the base of the catena. Annual plant biomass was higher on M. depilis and A. cockerelli nest soils than on the reference soils. Annual plant biomass was higher on P. rugosus nest soils than on reference soils at the base of the catena and in the grassland but not at the mid-slope and top of the catena. The effects of long-lived ant colony nests on soil properties and vegetation vary in time and space but are independent of the feeding behavior of the ant species.}, keywords = {aphaenogaster cockerelli, Generalist foragers, Honey-pot ants, microbial biomass, myrmecocystus depilis, Persistent nests, Pogonomyrmex rugosus, soil respiration}, doi = {doi:10.1016/j.jaridenv.2007.07.012}, url = {/files/bibliography/08-055.pdf}, author = {Walter G. Whitford and Barness, G. and Yosef Steinberger} } @article {50309, title = {Endosymbiotic fungi structually integrated with leaves reveals a lichenous condition of C4 grasses}, journal = {In Vitro Cellular and Development Biology - Plants}, volume = {43}, year = {2007}, month = {March 11, 2007}, pages = {65-70}, abstract = {This paper addresses the assumed autonomy of vascular plants by revealing the presence of an obligate fungus structurally integrated with leaf anatomy of C4 grasses. We examined leaf surfaces of 26 species representing 14 genera of C4 grasses. In all species, we found similarities between leaf surface microhair-like structures and Uredomycete teliospores. These bicellular structures produced hyphae and spores, confirming they were fungal, rather than plant tissue. The plant-fungus structural morphology was also observed in Bouteloua eriopoda plants regenerated from embryonic meristem cells. The conserved symbiosis between fungi and C4 grasses suggests a lichenous association with evolutionary significance. The structural integration of endosymbiotic fungi with cells and tissues offers novel and unexplored approaches to developing physiological, ecological and systematic models of C4 grasses.}, keywords = {C4 grasses, endosymbiotic, fungi, lichenous}, url = {/files/bibliography/07-013.pdf}, author = {J.R. Barrow and M.E. Lucero and I. Reyes-Vera and Kris Havstad} } @article {50327, title = {Effects of Eugenol, Alpha-Terpineol, Terpin-4-ol, and methyl eugenol on consumption of alfalfa pellets by sheep}, journal = {Small Ruminant Research}, volume = {73}, year = {2007}, month = {Septembe 10, 200}, pages = {272-276}, abstract = {Many secondary compounds are typically present in unpalatable shrubs on rangelands in the western United States. However, the relationship between intake by livestock and concentration of individual chemicals has been examined for very few of these compounds. Four experiments were conducted to examine effects of individual volatile compounds on intake of alfalfa pellets by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets with eugenol, {\textquoteright}-terpineol, terpin-4-ol, or methyl eugenol applied at one of five concentrations in an ethanol carrier. Treatments were multiples (0, 0.5, 1, 2, and 10X) of the concentration (X) of each compound on the leaf surface of Flourensia cernua. Treatment solutions were sprayed on alfalfa pellets (0.64 kg.lamb-1.d-1, DM basis), and consumption was measured during a 20-min interval for five days. A day effect (P < 0.001 for both linear and quadratic contrasts) was detected for intake in all four experiments, but no day x treatment interactions were observed (P > 0.05). The day effect was generally due to lower intake on day 1, except for the methyl eugenol experiment, in which lambs consumed more pellets on day 1. No treatment effects were observed (P > 0.05) for any of the four chemicals tested; thus, eugenol, {\textquoteright}-terpineol, terpin-4-ol, and methyl eugenol were not related to intake of alfalfa pellets by lambs under the conditions of this study.}, keywords = {diet selection, Herviory, intake, sheep, terpenes}, url = {/files/bibliography/07-026.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @conference {50326, title = {Effects of individual terpenes and terpene mistures on intake of lambs}, booktitle = {American Society of Animal Science}, volume = {85}, number = {Suppl. 1}, year = {2007}, month = {July 9, 2007}, pages = {287-288}, abstract = {Rangeland degradation due to shrub encroachment is a major concern to livestock producers and land managers in the western United States and in arid and semiarid regions worldwide. Most invasive shrubs contain secondary compounds that reduce their consumption by herbivores, but knowledge concerning the effects of specific compounds is limited. Four experiments were conducted to determine the effects of individual terpenes or mixtures of monoterpenes or sesquiterpenes on intake by lambs. After a 10-day adaptation period with untreated alfalfa pellets, lambs were individually fed treated alfalfa pellets for 20 min. each morning for 5 days. Five treatments (0X, .5X, 1X, 2X, and 10X; multiples of the concentrations of the same terpenes in Flourensia cernua) were applied to alfalfa pellets (637 g, DM basis) in an ethanol carrier. Except during the 20-m,in test, lambs were maintained outdoors and fed untreated alfalfa pellets (total mean intake = 4.7\%) in Exp. 1 and 4 because of greater intake of OX than other treatments on day 1 and lower intake for the 10XZ treatment on day 1 and 2. A trend for decreased intake (g/kg BW) as concentration of the sesquiterpene mixture increased was observed. Although there was a tendency for a sesquiterpene mixture to decrease intake, and the monoterpene mixture did not appear to affect intake by lambs.}, keywords = {alfalfa, alfalfa pellet, intake, lambs, shrubs, terpene}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @article {50344, title = {Ecological Services to and from rangelands of the United States}, journal = {Ecological Economics}, volume = {64}, number = {64}, year = {2007}, month = {November 2007}, pages = {261-268}, abstract = {

The over 300 million ha of public and private rangelands in the United States are characterized by low and variable precipitation, nutrient-poor soils, and high spatial and temporal variability in plant production. This land type has provided a variety of goods and services, with the provisioning of food and fiber dominating through much of the 20th century. More recently, food production from a rangeland-based livestock industry is often pressured for a variety of reasons, including poor economic returns, increased regulations, an aging rural population, and increasingly diverse interests of land owners. A shift to other provisioning, regulating, cultural, and supporting services is occurring with important implications for carbon sequestration, biodiversity, and conservation incentives. There are numerous goods and services possible from rangelands that can supply societal demands such as clean water and a safe food supply. The use of ecologically-based principles of land management remains at the core of the ability of private land owners and public land managers to provide these existing and emerging services. We suggest that expectations need to be based on a thorough understanding of the diverse potentials of these lands and their inherent limits. A critical provisioning service to rangelands will be management practices that either maintain ecological functions or that restore functions to systems that have been substantially degraded over past decades. With proper incentives and economic benefits, rangelands, in the U.S. or globally, can be expected to provide these historical and more unique goods and services in a sustainable fashion, albeit in different proportions than in the past.

}, keywords = {biodiversity, carbon sequentration, conservation, ecological remediation, incentives, natural ecosystems, provisioning services}, doi = {10.1016/j.ecolecon.2006.12.001}, url = {/files/bibliography/07-031.pdf}, author = {Kris Havstad and Debra C. Peters and R. K. Skaggs and Joel R. Brown and Brandon T Bestelmeyer and E.L. Fredrickson and Jeffrey E. Herrick and J. Wright} } @conference {50335, title = {Ecosystem Services from U.S. Rangelands: A Synthesis}, booktitle = {Society for Range Management Meeting Abstracts}, year = {2007}, abstract = {The over 300 million ha of public and private rangelands in the United States are characterized by low and variable precipitation, nutrient-poor soils, and high spatial and temporal variability in plant production. This land type has provided a variety of goods and services, with the provisioning of food and fiber dominating through much of the 20th century. More recently, food production from a rangeland-based livestock industry is often pressured for a variety of reasons, including poor economic returns, increased regulations, an aging rural population, residential development, and increasingly diverse interests of land owners. A shift to other provisioning, regulating, cultural, and supporting services is occurring with important implications for carbon sequestration, biodiversity, and conservation incentives. There are numerous goods and services possible from rangelands that can supply societal demands such as clean water and a safe food supply. The use of ecologically-based principles of land management remains at the core of the ability of private land owners and public land managers to provide these existing and emerging services. We suggest that expectations need to be based on a thorough understanding of the diverse potentials of these lands and their inherent limits. A critical provisioning service to rangelands will be management practices that either maintain ecological functions or that restores functions to systems that have been substantially degraded over past decades. With proper incentives and economic benefits, rangelands, in the U.S. or globally, can be expected to provide both historical provisioning and more unique goods and services in a sustainable fashion, albeit in different proportions than in the past.}, keywords = {ecosystem, rangeland}, author = {Kris Havstad} } @conference {50338, title = {Ecosystem services to and from North American arid grasslands}, booktitle = {IV Simposium Internacional de Pastezales}, year = {2007}, month = {August 22-24, 20}, pages = {1}, address = {San Luis Potosi, Mexico}, abstract = {Arid grasslands throughout North America are characterized by low and variable precipitation, nutrient-poor soils, and high spatial and temporal variability in plant production. These grasslands have provided a variety of goods and services, with the provisioning of food and fiber dominating through much of the 20th century. More recently, poor economic returns, increased regulations, an aging rural population, expanding urbanization, and/or increasingly diverse interests of land owners have pressured the traditional services originating from the rangeland livestock industry. A shift to other provisioning, regulating, cultural, and supporting services has occurred or is occurring in many regions. This shift has important implications for other services of increasing interest, such as biodiversity and carbon sequestration. We have always recognized that these lands can supply societal demands such as clean water and a safe food supply. Irrespective of the services and goods supplied, the use of ecologically-based principles remains at the core of land management. However, expectations need to be based on a thorough understanding of the inherent limits of these lands. One service to these lands that needs to be provided by managers is the use of practices that either maintains ecological functions or that restores functions to systems that have been substantially degraded over past decades. With proper policies, supporting science, and ecologically based management techniques, these grasslands may provide these historical and more unique goods and services in a sustainable fashion, though in different proportions than in the past.}, keywords = {grasslands, North America}, author = {Kris Havstad} } @article {50340, title = {Essays of a peripheral mind: Art and Science}, journal = {Rangelands}, volume = {29}, number = {1}, year = {2007}, note = {Trade Journal}, month = {February 28, 200}, pages = {36-38}, abstract = {An important new technology for management of rangelands is a state-and-transition model. This is a description of the vegetation communities that may occupy an ecological site, a kind of land with similar potential and response to management. These models, developed by people with experience and knowledge of specific ecological sites, represents what a site may have supported in the past, or possibly what a site can be managed for in the future. These models represent both the science of rangeland management and human interpretations (or artistic expressions) that are of value. Rangeland management is correctly viewed as a combination of both art in management and a science based on recorded observations.}, keywords = {art, essay, hooper, mind, nighthawks, peripheral, science}, url = {/files/bibliography/07-003.pdf}, author = {Kris Havstad} } @article {50336, title = {Essays of a peripheral mind: Faith}, journal = {Rangelands}, volume = {29}, number = {3}, year = {2007}, note = {Trade Journal}, month = {June 1, 2007}, pages = {59-60}, abstract = {Recently, the range management profession has been debating the advantages and disadvantages of rotational livestock grazing systems. Despite the lack of scientifically-based evidence in support of the benefits of rotational grazing in arid and semiarid environments, these systems are often promoted as ecologically and economically menial, or even counterproductive in some settings. Much of the promotion of these systems is based on personal observations, or beliefs, and not evidence drawn from experimental evidence. Rangeland management has always been described as an art and a science, and the strength of one{\textquoteright}s conviction are often based on both.}, keywords = {essay, faith, peripheral mind}, url = {/files/bibliography/07-019.pdf}, author = {Kris Havstad} } @article {50343, title = {Essays of a peripheral mind: Framing a story}, journal = {Rangelands}, year = {2007}, note = {Trade Journal}, month = {August 1, 2007}, abstract = {It is increasingly important to recognize that scientists can not just resort to conveying technical information on complex subjects. Scientists need to frame their information in both relevant and personal ways to capture the public{\textquoteright}s attention. Without that attention, there will be little interest in our findings, and little opportunity to effectively communicate information. The findings have to be framed in a fashion that will capture the initial attention of the reader to pursue the subject. Then, the scientist needs to effectively convey the complexities of those findings. Framing our research results in this fashion is a different style of communication than we typically employ, but essential if we are going to compete for the public{\textquoteright}s attention in a world driven by visualized digital communications.}, keywords = {peripheral, story}, url = {/files/bibliography/07-027.pdf}, author = {Kris Havstad} } @article {50345, title = {Essays of a peripheral mind: Nei4 Meng2gu3, Zhong1 Guo2}, journal = {Rangelands}, volume = {29}, number = {5}, year = {2007}, note = {Trade Journal}, month = {October 2007}, pages = {43-46}, abstract = {Inner Mongolia, China is the site of the 2008 International Rangeland Congress. There are over 500 million acres of grasslands in northern China. This is one of the largest remaining areas in the world still predominately used for livestock grazing. Over 20\% of these grasslands occur in Inner Mongolia. This region has an extensive recorded history of livestock grazing management defining to the 13th Century. Though the political, cultural, and economic characteristics of this region in China are distinctively different than the western world, there are many commonalities. These Asian rangeland landscapes are similar to the west, and scientific concepts and management principles originating from this region have application in the west.}, keywords = {China, Inner Mongolia}, url = {/files/bibliography/07-035.pdf}, author = {Kris Havstad} } @article {50342, title = {Essays of a peripheral mind: Speaking other languages}, journal = {Rangelands}, volume = {29}, number = {2}, year = {2007}, note = {Trade Journal}, month = {April 15, 2007}, pages = {65-66}, abstract = {Mongolian rangelands have been used for livestock production for hundreds of years. A pastoralist culture has been a key aspect of Mongolia throughout its 800-year history. Approximately 65\% of Mongolia{\textquoteright}s rural herders live at or below the poverty line, and there are few opportunities to improve resource conditions or economic returns. Yet, Mongolia is rebuilding its resource management profession following the withdrawal and collapse of the Soviet Union in the late 1990s. This essay is about the work of one Mongolian soil scientist and his efforts to work to stop resource degradation and to improve the condition of Mongolian rangelands.}, keywords = {essays, languages, Mongolia, peripheral, soil scientist}, url = {/files/bibliography/07-036.pdf}, author = {Kris Havstad} } @inbook {50351, title = {Estimating aboveground net primary production in grassland and herbaceous dominated ecosystems}, booktitle = {Principles and standards for measuring primary production}, year = {2007}, note = {//OTHER//LTER-V//entered 08/15/2007; updated 06/02/2008 per DEPProCite field[6]: In}, month = {2007}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, abstract = {

Although grass- and herb-dominated ecosystems may be easier to sample for aboveground primary production than most others, a variety of challenges for standardizing approaches in different settings and circumstances must be overcome. This chapter describes the most common harvest approaches for grassland production measurement and a suite of site-specific criteria that affect the choice of approach (e.g., grazing, decomposition, phenology). Errors leading to either underestimation or overestimation are examined, and a case study describing approaches for evaluating sample adequacy is provided.

}, keywords = {ANPP, book, chapter, grassland, ANPP method, method, aboveground net primary production, NPP, plant, ANPP, report, technique, aboveground NPP}, doi = {10.1093/acprof:oso/9780195168662.003.0003}, author = {A. K. Knapp and J. M. Briggs and Daniel L. Childers and O. E. Sala}, editor = {Fahey, Timothy J. and A. K. Knapp} } @article {50361, title = {Effect of reproductive modes and environmental heterogeneity in the population dynamics of a geographically widespread clonal desert cactus}, journal = {Population Ecology}, volume = {49}, year = {2007}, note = {//NMSU//LTER IV//entered 11/08/2005; updated 04/15/2008; PDF on file}, month = {2007}, pages = {141-153}, abstract = {

The dynamics of plant populations in arid environments are largely affected by the unpredictable environmental conditions and are fine-tuned by biotic factors, such as modes of recruitment. A single species must cope with both spatial and temporal heterogeneity that trigger pulses of sexual and clonal establishment throughout its distributional range. We studied two populations of the clonal, purple prickly pear cactus, Opuntia macrocentra, in order to contrast the factors responsible for the population dynamics of a common, widely distributed species. The study sites were located in protected areas that correspond to extreme latitudinal locations for this species within the Chihuahuan Desert. We studied both populations for four consecutive years and determined the demographic consequences of environmental variability and the mode of reproduction using matrix population models, life table response experiments (LTREs), and loop and perturbation analyses. Although both populations seemed fairly stable (population growth rate, λ\~{}1), different demographic parameters and different life cycle routes were responsible for this stability in each population. In the southernmost population (MBR) LTRE and loop and elasticity analyses showed that stasis is the demographic process with the highest contributions to λ, followed by sexual reproduction, and clonal propagation contributed the least. The northern population (CR) had both higher elasticities and larger contributions of stasis, followed by clonal propagation and sexual recruitment. Loop analysis also showed that individuals in CR have more paths to complete a life cycle than those in MBR. As a consequence, each population differed in life history traits (e.g., size class structure, size at sexual maturity, and reproductive value). Numerical perturbation analyses showed a small effect of the seed bank on the λ of both populations, while the transition from seeds to seedlings had an important effect mainly in the northern population. Clonal propagation (higher survival and higher contributions to vital rates) seems to be more important for maintaining populations over long time periods than sexual reproduction.

}, keywords = {article, Cactaceae, cactus, Opuntia, cactus, population dynamics, clonal growth, demography, journal, life history traits, loop analysis, LTRE analysis, matrix models, Opuntia, population dynamics, cactus, population dynamics, Opuntia}, doi = {10.1007/s10144-006-0032-2}, url = {files/bibliography/JRN00473.pdf}, author = {Mandujano, M. C. and Golubov, J. and L. Huenneke} } @conference {50367, title = {Ecology and management of savannas and semi-deserts of central Argentina}, booktitle = {Society for Range Mangement, 60th Annual Meeting and Trade Show}, number = {Paper No. 324}, year = {2007}, month = {02/2007}, address = {Reno/Sparks, NV}, abstract = {Vegetation of western pampas of central Argentina comprises: caldera, local name of a savanna to woodland ecosystem dominated by Prosopis caldenia; short-grassland and dune-grassland. The area include the central La Pampa and southern San Luis provinces, following a western precipitation gradient from 700 to 400 mm year-1. The caldenal typically occurs in valleys with loamy soils, while grasslands occur in flat uplands and sand dunes. The caldenal was originally featured by large sparse P. caldenia trees surrounded by a matrix of valuable thin short grasses dominated by Poa ligularis and Piptochaetium napostaense (flechillas). Shrub strata was only present in more marginal areas, as in dry slopes. Think grasses were also dominated in short (Stipa tenuis, P. napostaense, P. ligularis, Koeleria permollis), and dune grasslands (Sorgastrum pelitum). Nomadic cattle herding by Indians were widespread until mid 1800s. Major ecological changes occurred in early 1900s when livestock started being risen in fencing paddocks at high stocking rates. Sheep grazing was prevalent during the first half of 1900s and cattle grazing since then. Two severe periods of lodging for woods devastated the calendal in 1910s and 1940s. Lodging was also carried out to establish pastures and croplands. Human activities determine an increase in fire frequency. Currently, almost all calendal cover area comprises secondary forest with a poorly represented tall strata (6-10m) and well represented shrub strata. Grass strata shifted to bunch grasses of low palatability. Similarly, a shift to low valuable grasses and forbs occurred in grasslands. Woody encroachment mostly driven by the dispersion of P. caldenia seed by cattle, is a prevalent problem in both caldenal and grasslands. Woody encroachment increased the likelihood and intensity of fires. Current management focus in improving forage availability through controlled fires. However, there is need for an integrated management approach to restore degraded ecosystems.}, keywords = {Argentina, caldera, ecology, management, savannas}, author = {H. Raul Peinetti and Fernandez, G. and A. Kin and Morici, E.} } @article {50378, title = {Effects of temporally persistent ant nests of soil protozoan communities and the abundance of morphological types of amoeba}, journal = {Applied Soil Ecology}, volume = {37}, year = {2007}, month = {04/2007}, pages = {81-87}, abstract = {We compared soil protozoan communities near ant nests with soil protozoans in reference soils 5m from the edge of any mounds. We sampled three species of Chihuahuan Desert ants that construct nests that persist for more than a decade a seed harvester, Pogonomymex rugosus, a liquid feeding honey-pot ant, Myrmecocystus depilis, and a generalist forager, Aphaenogaster cockerelli. Ant colonies were located on different topographic positions on catenas of two watersheds. Total protozoan abundance was higher in P. rugosus nests soils at the tope of a catena and in A. cockerelli nest soils in a grassland than in the respective reference soils. There were qualitative and quantitative differences in protozoan communities associated with the nests of ants at all locations studied. Amoebae were the most abundant protozoans at all locations. Type 1 amoebae (flattened with sub-pseudopodia (like Acanthamoeba) occurred at the highest frequency and was the only amoeba type found in M. depilis nest soils and P. rugosus nest soils at the tope of a catena. Nanoflagellates were associated with P. rugosus and M. depilis nest soils but were absent from reference soils. Ciliates, testate amoebae and nanoflagellates were absent from A. cockerelli reference soils but were present in nest soils. The effects of ants on soil protozoan communities depend on the temporal persistence of the colony, nest building and food handling behavior, topographic position and soil type.}, keywords = {aphaenogaster cockerelli, catena, ciliates, flagellates, myrmecocystus depilis, nanoflagellates}, doi = {10.1016/j.apsoil.2007.04.002}, url = {/files/bibliography/07-034.pdf}, author = {Rodriguez-Zaragosa, S. and Walter G. Whitford and Yosef Steinberger} } @conference {50390, title = {Effects of goats on Tamarix spp. and understory vegetation for riparian restoration}, booktitle = {Society for Range Management 60th Annual Meeting and Trade Show}, year = {2007}, month = {02/2007}, pages = {Paper No. 425}, abstract = {Goats were used to reduce Tamarix spp. along the Rio Grande in New Mexico. Seventy 0.1-1.6 ha plots at two locations were either browsed by 400-630 goats for 1-3 days annually, or left unbrowsed. After two annual treatments, nearly every available Tamarix plant in mixed vegetation was browsed (100\%), broken (91\%) or debarked (60\%). Goats reduced the Leaf Area Index of resprouts by about 24\% each year. However, nearly all of the Tamarix biomass that was removed regrew between annual treatments. During the second year, goats reduced the mean height of Tamarix by 8\% and the mean width by 21\% in open-canopy mixed vegetation. Overall, the number of Tamarix decreased by less than 5\% after three years of goat browsing treatments. In large, dense, closed-canopy Tamarix, goats opened up the understory, reduced laddering fuels and improved access, potentially reducing costs of subsequent mechanical or manual clearing. Rusian olive (Elaeagnus angustifolia) was heavily browsed and cover declined about 10\% per year. Large cottonwoods (Populus deltoides) were not damaged, but small cottonwoods were heavily browsed. Willows (Salix spp.) were browsed and resprouted vigorously. Goats increased the area of bare soil by about 20\% and reduced the cover of most understory plant species, including native perennial grasses, such as Sporobolus spp. The cover of native annual grasses associated with disturbance (Bouteloua barbatus, B. aristoides) increased from less than 1\% to about 20\% one year after browsing, following substantial rainfall. Goats may be useful, in combination with other methods, for controlling Tamarix resprouts or where partial control of Tamarix is desired. Goats may be especially effective in removing understory weeds and preparing the seed bed for vegetation. The use of livestock for land management and ecological restoration, rather than production of agricutlural commodities, offers new economic opportunity for entrepreneurial ranchers.}, keywords = {goats, Rio Grande, riparian, Tararix, vegetation}, author = {S. Tartowski and D. K. James} } @conference {50393, title = {An evaluation of the dynamic soil properties pilot project in Arches National Park, Utah}, booktitle = {60th Annual Meeting and Trade Show, Society for Range Management}, year = {2007}, month = {02/09/2007}, pages = {Paper No. 442}, address = {Sparks/Reno, NV}, abstract = {Dynamic soil properties are gaining increasing attention by producers and users of soil survey data. Near-surface property data, along with vegetation characteristics, provides soil survey users with important new tools, and is a valuable aid in the development and monitoring of state in transition models for ecological site descriptions. Protocols for measuring and interpreting dynamic soil properties are inadequately addressed in standard soil survey procedure; therefore, there is a need to define these protocols. A pilot study for the collection of dynamic soil properties was conducted in Arches National Park, Utah in 2005. In addition to providing the park with information for evaluating and managing visitor impact on park soils, it was a chance of test sampling procedures, and refine the sampling techniques for use in other soil survey areas throughout the country. The sampling was conducted on Begay soils under two plant communities of the Semidesert Sandy Loam (fourwing saltbush) ecological site; a mixed perennial grass/shrub community (PGSL), and a cheatgrass-invaded community (INL). Vegetation properties sampled included herbaceous production, and basal and canopy cover, while soil properties included aggregate stability, bulk density, penetration resistance, carbon fractions and CaCO3\% for multiple depth intervals.}, keywords = {Arches National Park, soil properties, Utah}, author = {Truman, D. and Scott, C. and A.J. Tugel and J.P. Ward and Parslow, V. and Biggam, P. and Fitsimons, B. and C. Seybold} } @article {50411, title = {Effects of Feral Horses in Great Basin Landscapes on Soils and Ants: Direct and Indirect Mechanisms}, journal = {Journal of Arid Environments}, volume = {66}, number = {1}, year = {2006}, month = {January 2006}, pages = {96-112}, abstract = {We compared soil-surface penetration resistance and abundance of ant mounds at 12 western Great Basin sites (composed of 19 plots) either grazed by feral horses (Equus caballus) or having had horses removed for the last 10\–14 years. Across this broad spatial domain (3.03 million ha), we minimized confounding due to abiotic factors by selecting horse-occupied and horse-removed sites with similar aspect, slope, \&$\#$39;re history, grazing pressure by cattle (minimal to none), and dominant vegetation (Artemisia tridentata). During both 1997 and 1998, we found 2.2\–8.4 times greater abundance of ant mounds and 3.0\–15.4 times lower penetration resistance in soil surfaces at horse removed sites. In 1998, thatched Formica ant mounds, which existed predominately at high elevations, were 3.3 times more abundant at horse-removed sites, although abundance varied widely among sites within treatments. Several types of analyses suggested that horses rather than environmental variability were the primary source of treatment differences we observed in ecosystem components. Tests of several predictions suggest that alterations occurred through not only direct effects, but also indirect effects and potentially feedback loops. Free-roaming horses as well as domestic grazers should be considered in conservation planning and land management in the Great Basin, an ecoregion that represents both an outstanding conservation opportunity and challenge. http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-4HWX8YM-1-17\&_cdi=6845\&_user=1496926\&_orig=browse\&_coverDate=07\%2F31\%2F2006\&_sk=999339998\&view=c\&wchp=dGLzVzz-zSkzS\&md5=1d287ea8843005be3bea26ad74d18846\&ie=/sdarticle.pdf}, keywords = {conservation, disturbance, Equus caballus, feral horses, formica, Nevada, pogonomyrmex}, url = {/files/bibliography/06-025.pdf}, author = {E.A. Beever and Jeffrey E. Herrick} } @article {50434, title = {Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts}, journal = {Journal of Eukaryotic Microbiology}, volume = {53}, number = {6}, year = {2006}, note = {//USDA//USGS//Entered 11/21/2006}, month = {2006}, pages = {507-514}, abstract = {Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 1C. Cysts survived the upper end of daily temperatures (37{\textendash}55 1C), and could be stimulated to excyst if temperatures were reduced to 15 1C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert{\textquoteright}s temperature and precipitation regime.}, keywords = {article, Chihuahuan Desert, climate change, Colorado Plateau, cryptobiotic crust, environmental stress, journal, soil change, soil function, soil crust, biological, soil fauna, soil food webs, soil protozoa, soil, ecosystem function, soil, food web, soil, methods, thermotolerance}, isbn = {DOI: 10.1111/j.1550-7408.2006.00134.x}, author = {Darby, Brian J. and Housman, David C. and Zaki, Amr M. and Shamout, Yassein and Adl, Sina M. and Jayne Belnap and Neher, Deborah A.} } @inbook {50443, title = {Eolian processes across the Jornada basin}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem. The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {189-210}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {9}, address = {New York}, abstract = {In arid and semiarid lands, soil erosion by wind is an important process that affects both the surface features and the biological potential of the ecosystem. The eolian flux of soil nutrients into or out of an ecosystem results in enrichment or impoverishment of its biological potential. In the Jornada Basin, wind erosion is the only significant mechanism for the net loss of soil materials because fluvial processes do not remove materials from the basin. Vigorous wind erosion leads to topographic changes, altering the growing conditions for plants and animals. Examples of such changes in topography are the formation of sand dunes or the removal of whole soil horizons. Our goal in this chapter is to describe the construction of a mathematical model for wind erosion and dust production for the Jornada Basin. The model attempts to answer the following questions:1. Which soils are affected by wind erosion?2. How does wind erosion occur on Jornada soils?3. Does changing vegetation cover lead to a change in the source/sink relationship? 4. Is the Jornada a source or sink of eolian materials? If it is a source, what materials are lost?5. How does wind erosion change the soil-forming process?}, keywords = {biological, ecosystem, eolian, erosion, soil, wind}, url = {/files/bibliography/06-060.pdf}, author = {D. E. Gillette and Curtis H. Monger}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @conference {50447, title = {Ecosystem Services from Grazed Rangeland in the Arid and Semi-Arid West}, booktitle = {American Association for the Advancement of Science Annual Meetings}, year = {2006}, month = {February 16-20, }, pages = {A 5}, address = {St. Louis, MO}, abstract = {Over 500 million acres of public and private rangelands are in the western United States. These diverse environments also provide wildlife habitat (including for species listed as threatened or endangered), regulate water flow and quality, make available outdoor recreation, and preserve open spaces for expanding urban environments. Under careful management, livestock grazing can produce drastically fewer negative impacts on eocsystem services and remarkable positive impacts as well. However, appropriate management practices by ranchers are the key to providing these additional ecosystem services from over 25\% of the land surface of the United States.}, keywords = {endangered, rangelands, threatened, wildlife}, author = {Kris Havstad} } @conference {50449, title = {Effectiveness of Grazing Systems - A Snythesis of Evidence}, booktitle = {Society for Range Management 59th Annual Meeting and Trade Show}, year = {2006}, month = {February 12-17, }, pages = {158}, address = {Vancouver, British Columbia, Canada}, abstract = {The general body of evidence in support of the use of grazing systems for sustained production from and health of rangelands is underwhelming, at best. This is despite decades of scientific investigations, conservation programs, and textbook promotion of grazing systems as logical components of rangeland management. In early 20th Century North America, control over grazing was initially touted to regulate seasonal initiation and distribution of grazing. In this sense, grazing systems were delayed turn-out dates, salting and water placements, and herding practices. These systems morphed into more infrastructure and intensive practices built across landscapes to control periods of animal access and more evenly distribute grazing pressure. However, research and observation have shown that access to increasingly large areas of land ameliorates quality of available forages, and at any point in time foraging behaviors are consistently species-specific, as 4-6 plant species will comprise the bulk of an animal{\textquoteright}s diet. The papers in this symposium will illustrate that 1) minimal documentation exists that confirms pasture level controls over this specificity for plant species will actually affect the status of the land or of the grazing animal, and 2) the confounding influence of the extensive heterogeneity inherent within native rangelands constrains the effectiveness of traditional, short-term reductionist experimentation. Unsubstantiated rationales for adoption of these practices by practitioners further contribute to a restrained regard for grazing systems. Management of grazing is less about structural pasture-level controls over tiller and individual plant defoliation by livestock, and more about implementation of a suite of strategies that diversify tillers, species, and patches available for defoliation.}, keywords = {grazing systems, health, sustained production}, author = {Kris Havstad} } @article {50453, title = {Essays of a peripheral mind: Clean and simple, but stupid}, journal = {Rangelands}, volume = {28}, number = {6}, year = {2006}, note = {Trade Journal}, month = {December 2006}, pages = {22-23}, abstract = {Rangelands of the U.S. are still providing basic provisionary sciences, such as food production, that they have over the past 150 years. However, these services are diminishing as Americans demand other products form these landscapes. This essay discusses a specific example of the demand for recreation that is having an important impact on the use of rangelands in California{\textquoteright}s Central Valley. Because of the unnecessary use of rangelands by the general public, professional technical organizations need to work more closely with these newer areas to communicate the principles for managing these rangelands to support these newer goods and services.}, keywords = {California Central Valley}, url = {/files/bibliography/06-038.pdf}, author = {Kris Havstad} } @article {50465, title = {Echohydrolgical Feedbacks and Lindates Associated with Land Degradation: A Case Study from Mexico}, journal = {Hydrological Processes}, volume = {20}, year = {2006}, note = {ProCite field[3]: December 28, 2005ProCite field[28]: August 16, 2005}, pages = {3395-3411}, abstract = {Desertification is a major environmental problem of global drylands. The human activities that contribute to land degradation also negatively impact hydrology, which can lead to crises in water resources. Whereas this is commonplace in the arid and semiarid regions of the globe, including the Americas, these problems are especially acute in Mexico. In this paper, we report on findings from a workshop convened by the ARIDnet network on land degradation in La Amapola, a small rural community in the Central Plateau of Mexico. Using the village of La Amapola as a model \‘test case\’, we focused on the links between desertification and the hydrological cycle. Although there is a paucity of data for this isolated village, La Amapola served as an excellent case study: it is located within a highly degraded landscape, both socioeconomic and biophysical drivers are currently in force, freshwater is crucial to agrarian livelihoods, and it is similar to many rural communities worldwide facing similar land degradation concerns. Importantly, applying the DDP to La Amapola afforded us an excellent opportunity to develop a research and restoration agenda for the region. Each household in La Amapola is involved in a complex interplay between multiple variables, bounded by biophysical and socioeconomic thresholds. We summarize our findings in a conceptual model that is based on (i) the partitioning of \‘shared water\’ between society and nature and (ii) the Dahlem Desertification Paradigm (DDP), the latter of which highlights the numerous connections (direct and indirect) between the biophysical \‘state of the ecosystem\’ and the \‘rural livelihoods\’ of individuals living there. The DDP consists of various assertions that stress the inseparable interplay of both human and environmental drivers in desertification. In our conceptual model, hydrological functions are shown as crucial elements of both the natural ecosystem (e.g., rainfall,run-off, evaporation) and the socioeconomic system (e.g., drinking water, profit from crop yield, water for sanitation). We demonstrate from the many feedbacks, linkages, and causal pathways between the biophysical and human dimensions that hydrology is a fundamental component of the rural livelihood of rural communities, and thus it is of central importance when evaluating desertification.}, keywords = {degradation, Mexico}, url = {/files/bibliography/06-076.pdf}, author = {E. Huber-Sannwald and F. Maestre and Jeffrey E. Herrick and J. F. Reynolds} } @article {50476, title = {Effects of grazing and shrub removal on small mammal populations in southern New Mexico, USA}, journal = {Journal of Arid Environments}, volume = {66}, year = {2006}, note = {//USDA//LTER IV//entered 02/29/2008}, month = {2006}, pages = {76-86}, abstract = {

Between 1995 and 1997, grazing regimes and mesquite (Prosopis glandulosa) shrub removal were combined in a factorial arrangement to assess changes in small mammal communities on the Jornada Experimental Range in southern New Mexico. Small mammals were live-trapped biannually in winter and at the end of the growing season (fall). We examined changes in abundances, species richness, species and biomass diversity, and mean captures and biomass. Species richness did not change significantly with treatments but was seasonally higher in spring 1996 compared to the fall 1996. A decrease in species and biomass diversities were seen in fall 1996 and an increase in both diversities in fall 1997. No plots reached the same species richness, abundance, or diversity encountered during a pre-treatment study in 1993. Spring 1995 and fall 1996 revealed significant reactions to the combination of the applied treatments, yet no overall pattern can be elucidated. Environmental fluctuations such as variable rainfall and inherent stochasticity of the ecosystem may explain the lack of pattern, and only emphasizes the need for more long-term studies assessing the effects of vegetation alteration on dependent communities. {\textcopyright} 2005 Elsevier Ltd. All rights reserved.

}, keywords = {American Southwest, Chihuahuan desert; Grazing, prosopis glandulosa, shrub removal, small mammals}, doi = {10.1016/j.jaridenv.2005.10.015}, url = {files/bibliography/JRN1615.pdf}, author = {Mathis, V. L. and Walter G. Whitford and F. R. Kay and P.U. Alkon} } @article {50544, title = {Effect of previous exposure of sheep to monoterpene odors on intake of alfalfa pellets treated with camphor or alpha-pinene}, journal = {Small Ruminant Research}, volume = {58}, year = {2005}, note = {This is not a duplicate; ARIS No. 151564 has same title but is an abstract submitted for a meeting. }, month = {April 1, 2005}, pages = {33-38}, abstract = {Lambs were subjected to odors of two monoterpenes (camphor and alpha-pinene) that decreased intake in a previous study to determine if exposure during feeding modified their effects on subsequent intake. Two experiments were conducted using a split-plot design and with 36 ewe lambs (mean BW = 23.1 and 42.2 kg in Exp. 1 and 2, respectively) group-fed alfalfa pellets (3.8\% of BW, DM basis) in enclosed portable buildings for 2 h each morning for 56 d. Nine lambs were randomly assigned to each of four buildings, and 25 g of camphor (Exp. 1) or 50 ml of alpha-pinene (Exp. 2) were placed in a mesh-covered container in the center of the feeder in two buildings immediately before feeding. After the 8-wk exposure period (phase 1), lambs were individually fed alfalfa pellets (640 g, DM basis) for 20 min each morning for 10 d (5-d adaptation, 5-d collection) in a metabolism building (phase 2). Treatments were sprayed on alfalfa pellets at levels representing the concentration of that chemical in Flourensia cernua or at 10-fold that concentration. Controls received the ethanol carrier only. During phase 2, lambs were fed in three groups (n = 12), stratified such that one lamb from each building received each treatment in each group. Lambs were housed as one group and fed alfalfa pellets at 4.7\% of BW (DM basis) except during the 20-min tests. No interactions with day were detected for intake during adaptation or collection periods for either chemical (P > 0.05); therefore, data were pooled across day. Exposure to the volatile aroma for 8 wk had no effect on intake during the subsequent 10-d interval for either monoterpene (P > 0.05). Moreover, intake during the collection period was not affected by treatment concentration (P > 0.05). Neither concentration of the terpene applied to alfalfa pellets nor previous exposure to the volatile aroma from camphor or alpha-pinene altered feed intake under the conditions of this study.}, keywords = {herbivory, intake, monoterpenes, olfaction, sheep}, url = {/files/bibliography/05-022.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50545, title = {Effects of eugenol, terpin-4-ol, alpha-terpineol, and methyl eugenol on consumption of alfalfa pellets by sheep}, booktitle = {2005 Annual Meeting of American Society of Animal Science}, volume = {83 (Suppl. 1)}, year = {2005}, month = {July 24, 2005}, pages = {274}, address = {Cincinnati, OH}, abstract = {Secondary compounds present in shrubs on rangelands in the western United States are often aversive to livestock. However, effects of many of these compounds on intake have not been individually tested. Four experiments were conducted to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either eugenol, terpin-4-ol, alpha-terpineol, or methyl eugenol at one of five concentrations in an ethanol carrier. Treatments (0, 0.5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (0.64 kg.lamb1.d1, DM basis), and consumption was measured during a 20min interval for 5 d. Lambs were adapted to handling and individual pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20 min tests) at a mean total daily intake of 3.9\% of BW (DM basis). A day effect (P< 0.0001) was detected for intake in all four experiments, but no day x treatment interactions were observed (P> 0.05). The day effect was generally due to lower intake of alfalfa pellets on day 1, except for the methyl eugenol experiment, in which lambs consumed more pellets on day 1. No treatment effects were observed (P> 0.05) for any of the four chemicals tested; thus, none of these chemicals were strongly related to intake of alfalfa pellets by lambs under the conditions of this study.}, keywords = {herbivory, intake, terpene}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @article {50547, title = {Effects of gamma-terpinene, terpinolene, alpha-copaene, and alpha-terpinene on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {83}, year = {2005}, month = {August 15, 2005}, pages = {1967-1971}, abstract = {Although plant secondary chemistry influences shrub consumption by free-ranging ruminants, the effects of many specific compounds on herbivory have not been examined. We conducted four experiments to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either gamma-terpinene, terpinolene, alpha-copaene, or alpha-terpinene at one of five concentrations in an ethanol carrier. Treatments (0, 0.5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (0.64 kg.lamb-1.d-1, DM basis), and consumption was measured during a 20-min interval for 5 d. A day effect (P \< 0.02) was detected for gamma-terpinene on intake (P \< 0.0001 for both linear and quadratic contrasts). A treatment effect (P \< 0.02) was observed for alpha-copaene with intake on the 2X treatment lower than other treatments. No effect of terpinolene or alpha-terpinene on intake was detected in this study. None of the chemicals tested were strongly related to intake of alfalfa pellets by lambs under the conditions of this study. http://jas.fass.org/cgi/reprint/83/8/1967}, keywords = {diet selection, herbivory, intake, sheep, terpenes}, url = {/files/bibliography/05-013.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @conference {50557, title = {Ecological sustainability in the Chihuahuan Desert: Is rangeland health relevant?}, booktitle = {Society for Range Management, 58th Annual Meeting and Trade Show}, year = {2005}, month = {February 5, 2005}, pages = {Paper No. 169}, address = {Fort Worth, TX}, abstract = {Rangeland health is increasingly promoted as a universal rangeland management objective. A protocol for interpreting indicators of rangeland health developed by a US interagency team has been extensively applied throughout the US and northern Mexico. A new version based on input from both the US and Mexico will be available in both Spanish and English in 2005. The protocol has been used to increase understanding of ecological properties and processes, and to assess the current status of those processes relative to their potential. While debates about the appropriate application of the protocol continue, it has been accepted and applied by many scientists and land managers in the US and Mexico. There has, however, been little critical evaluation of the relevance of either the specific protocol or the general concept of rangeland health to sustainability. The objectives of this paper are to provide an overview of the application of rangeland health on both sides of the border, and to critically evaluate not only its relevance to ecological sustainability, but also to socioeconomic sustainability, in order to better focus evaluations on those regions where management decisions are likely to be influenced by an increased understanding of rangeland health. We conclude that even a relatively rudimentary socioeconomic analysis may increase the cost-effectiveness of rangeland health evaluations.}, keywords = {Chihuahuan Desert, ecological properties and processes, ecological sustainability, rangeland health}, author = {Jeffrey E. Herrick and Foladori, G. and Melgoza, A.} } @proceedings {50558, title = {Evaluation of the status of rangeland health: towards the future}, year = {2005}, month = {April 20-21, 200}, pages = {79}, address = {Zacatecas, Mexico}, abstract = {

In recent years, the health status assessment of grasslands has been greatly improved with the integration of ecological concepts. The "Interpreting Indicators of Rangeland Health" guide, version 3, was developed to provide a rapid assessment of grassland health. This guide uses 17 indicators that evaluate three attributes of grassland health: soil and site stability, hydrological functionality, and biotic integrity. Now it{\textquoteright}s being applied to various goals, including helping producers focus their management on areas that have a high risk of degradation, or a high probability for renewal. With the publication of version 4.0 in 2005, evaluations have been standardized with a "reference sheet" for each "ecological site" (a soil group that has a similar potency for the production of plant communities). This reference sheet provides a description of the normal variability ranges in the potential condition for each of the 17 indicators. Some quantitative indicators have also been integrated. In the future, it is hoped to make the process even more quantitative, and improve the application of the process at the landscape level. Specifically, it is expected to interpret the effects of the areas surrounding the evaluation area (e.g. runoff). The ultimate goal is to make it as easy, repeatable as possible and, at once, make the results more relevant to producers and other landowners.

En los {\'u}ltimos a{\~n}os se ha mejorado mucho la evaluaci{\'o}n del estado de salud de los pastizales con la integraci{\'o}n de conceptos ecol{\'o}gicos. La gu{\'\i}a {\textquotedblleft}Interpreting Indicators of Rangeland Health{\textquotedblright}, versi{\'o}n 3, fue desarrollada con el objetivo de proveer una evaluaci{\'o}n r{\'a}pida de la salud de los pastizales. Esta gu{\'\i}a utiliza 17 indicadores que eval{\'u}an tres atributos de la salud de los pastizales: estabilidad del suelo y sitio, funcionalidad hidrol{\'o}gica e integridad bi{\'o}tica. Ahora se lo esta aplicando a varios objetivos, incluyendo ayudar a los productores enfocar su manejo en {\'a}reas que tiene un alto riesgo de degradaci{\'o}n, o una alta probabilidad para renovaci{\'o}n. Con la publicaci{\'o}n de versi{\'o}n 4.0 en 2005, se ha estandardizada las evaluaciones con una {\textquotedblleft}hoja de referencia{\textquotedblright} para cada {\textquotedblleft}sitio ecol{\'o}gico{\textquotedblright} (grupo de suelos que tiene una potencia parecido para la producci{\'o}n de comunidades de plantas). Esta hoja de referencia provee una descripci{\'o}n de los rangos normales de variabilidad en la condici{\'o}n potencial para cada uno de los 17 indicadores. Tambi{\'e}n, se ha integrado algunos indicadores cuantitativos. En el futuro, se espera hacer el proceso todav{\'\i}a m{\'a}s cuantitativo, y mejorar la aplicaci{\'o}n del proceso al nivel del paisaje. Espec{\'\i}ficamente, se espera interpretar los efectos de las {\'a}reas que rodean el {\'a}rea de evaluaci{\'o}n (por ejemplo escurrimiento). El objetivo final es hacerlo tan f{\'a}cil, repetible como posible y, de una vez, hacer los resultados mas relevante para los productores y otros due{\~n}os de tierras.

}, keywords = {evaluation, future, rangeland health, status}, author = {Jeffrey E. Herrick and D.A. Pyke and P. L. Shaver and M. Pellant and Melgoza, A.} } @article {50563, title = {ECOTONE Manual}, number = {ERDC/CERL CR-05-2}, year = {2005}, month = {November 2005}, pages = {11 pages}, publisher = {U.S. Corps of Engineers}, address = {Washington, DC}, abstract = {

The U.S. Department of Defense is responsible for managing over 25 million acres of land using a variety of programs, tools, and procedures to periodically assess and evaluate land condition. One tool, the ECOTONE model, was set up to simulate vegetation recovery from military disturbances on Fort Bliss, Texas, as a conceptual structure to prioritize the research efforts in land management. This report provides documentation of the structure and function of the ECOTONE model. The model consists of processes - dispersal, establishment, growth, etc. - that flow into each other and are influenced by disturbances that result in varying degrees of plant mortality.

}, keywords = {ECOTONE, government publication, Manual}, doi = {http://owww.cecer.army.mil/techreports/Fehmi_ecotone_manual/Fehmi_CR-05-2.pdf}, url = {/files/bibliography/06-018.pdf}, author = {Hochstrasser, T. and Debra C. Peters}, editor = {U.S. Corps of Engineers, Engineer Research and Development Center/Construction Engineering Research Laboratory} } @article {50566, title = {Ecohydrological implications of woody plant encroachment}, journal = {Ecology}, volume = {86}, number = {2}, year = {2005}, month = {February 1, 2005}, pages = {308-319}, abstract = {Increases in the abundance or density of woody plants in historically semiarid and arid grassland ecosystems have important implications for hydrology, ecology, and society. Using a simplified water-balance model, we propose a framework for conceptualizing how woody plant encroachment is likely to affect components of the water cycle within these ecosystems. We focus in particular on streamflow and the partitioning of evapotranspiration into E (evaporation) and T (transpiration). On the basis of this framework, we suggest that streamflow and evaporative processes are affected by woody plant encroachment in different ways, depending on the degree of aridity and the availability of subsurface water. Differences in landscape physiography, climate, and runoff mechanisms mediate the influence of woody plants on hydrological processes. Similarly, encroachment of woody plants can be expected to produce relatively large shifts in the ratio of E to T in semiarid ecosystems, whereas such shifts will be small or negligible in both subhumid and xeric ecosystems. This framework for considering the effects of woody plant encroachment highlights important ecological and hydrological interactions that serve as a basis for predicting other ecological aspects of vegetation change,such as potential changes in carbon cycling within an ecosystem. In locations where woody plant encroachment results in increased T and concurrently the availability of soil water is reduced, increased accumulation of carbon in soils can be predicted. Thus, explicitly considering the ecohydrological linkages associated with vegetation change provides additional information on the consequences of woody plant encroachment. http://www.esajournals.org/pdfserv/i0012-9658-086-02-0308.pdf}, keywords = {arid, ecohydrological, ecosystems, evapotranspiration, semiarid, woody plant encroachment}, url = {/files/bibliography/05-006.pdf}, author = {T. Huxman and Wilcox, B.P. and R.L. Scott and K. A. Snyder and Small, E.E. and Hultine, K.R. and Pockman, W.T. and R. B. Jackson} } @conference {50574, title = {Enhancement of chile biomas, fruit quality, and drought stress tolerance by inoculation with native plant endophytes}, booktitle = {20th Annual Southwest Consortium on Plant Genetics and Water Resources}, year = {2005}, month = {August 18-20, 20}, pages = {6}, publisher = {Texas A\&M}, organization = {Texas A\&M}, address = {Santa Ana Pueblo, NM}, abstract = {Recognition of the important contributions endophytes make to plant stress tolerance, defense, and production has grown exponentially with improvements in detection of unculturable microorganisms in plant tissues. Recently, the ability to manipulate host-endophyte combinations has provided a powerful tool for plant improvement and offered a host of new opportunities for metabolic engineering. Endophytes obtained from plants native to the Chihuahuan desert have demonstrated remarkable potential to transform forage grasses, tomatoes, and Arabidopsis, increasing overall biomass, nutrient uptake, and fruit production. The mechanisms by which these improvements occur are not fully understood. Microscopic examination of fungal biofilms on plant surfaces, in guard cells, and in vascular tissues suggest direct roles in water and nutrient management. The proposed study will utilize chile plant as model systems for analysis of changes in gene expression and metabolism following inoculation with foreign endophytes. Treated and untreated chile will be raised from seedlings in a controlled greenhouse environment. PCR and in situ hybridization of leaf tissue will verify changes in systemic endophyte populations following inoculation. Plant growth measurements such as height, days until flowering, numbers of flowers and fruit produced and biomass will be recorded. Samples from young and mature tissues will be harvested for biochemical analysis of organic extracts, and for RNA analysis. Gene expression analysis will determine the abundance of transcripts related to drought stress, photosynthesis, and secondary metabolism. This research will directly address SWC goals of determining and evaluating plant genetic, developmental, biochemical, and physiological responses that affect the growth and yield of a regionally important crop species.}, keywords = {endophytes, microorganisms, plant tissues}, author = {M.E. Lucero and M. A. O{\textquoteright}Connell} } @conference {50579, title = {Efforts to evaluate range health in northern Mexico}, booktitle = {58th Annual Meeting of the Society for Range Management}, year = {2005}, month = {February 5, 2005}, pages = {Abstract No. 228}, abstract = {Rangeland health evaluations provide specialists with an important tool that can be used to help increase rangeland sustainability. There are several publications for evaluation and monitoring of single products and or services; however, an integrated ecological approach is more appropriate where rangeland is managed to support multiple objectives. A US interagency group with significant input from INIFAP (Mexico) scientists has developed an integrated ecological approach based on three ecological attributes: soil and site stability, hydrologic function, and biotic integrity. These attributes are evaluated using 17 qualitative indicators. The qualitative evaluations can be supported by a number of quantitative measurements, which can also be used for monitoring. Six workshops have been conducted in Mexico, where approximately 200 participants have been trained. Ranchers, several protected areas, and research projects are using this methodology. Evaluation of a site is made based on a reference sheet that is developed for a suite of similar soils. In the past, reference areas were often used in place of the reference sheet. However, it is often not possible to find an appropriate reference area, and reliance on individual reference areas ignores other valuable knowledge sources. The process of completing the reference sheets often leads to the identification of knowledge gaps that can be addressed with research. Current challenges include developing consistent terminology, methods, analysis, and interpretation. There is a great opportunity to share experiences and strategies for increasing the accuracy and efficiency of the application of this protocol on both sides of the border.}, author = {Melgoza, A. and Royo, M. and Jeffrey E. Herrick} } @article {50597, title = {Ecological and geographical scale: Parallels and potential for integration}, journal = {Progress in Human Geography}, volume = {29}, year = {2005}, month = {06/2005}, pages = {276-290}, chapter = {276}, abstract = {

Scale has emerged as a major conceptual issue in both ecology and human geography in recent decades, due principally to the appearance of new global problems and processes that challenge conventional disciplinary theories and methods. Yet, very little work has examined ecological and geographical scale side by side or attempted to bring them into constructive engagement. This is unfortunate because human geography can help address ecologists\&$\#$39; expressed need for greater attention to political and economic processes affecting ecosystems and because ecological scale can provide needed conceptual and methodological clarity to \&$\#$39;the scale question\&$\#$39; in geography. This paper reviews recent debates about scale in the two disciplines and presents the case for integration, not by reduction of geographical problems to ecological ones but on the basis of a shared interest in understanding the complex interactions of multiscaled processes. Three distinctions articulated by ecologists are missing from the debate among human geographers: between scale and level, between empirical and methodological dimensions of scale, and, within the methodological dimension, between grain and extent. I show how these distinctions help resolve recent disputes in human geography, outline a framework for research on scale, and illustrate my points with a brief case study.

}, keywords = {ecological scale, geographical scale, human geography, rabgeland ecology, scaling effects, thresholds}, doi = {10.1191/0309132505ph546oa}, url = {/files/bibliography/05-026.pdf}, author = {N. F. Sayre} } @conference {50624, title = {Effects of methods of exposure to eastern red cedar foliage on cedar consumption by Boer crossbred wether goats}, booktitle = {Dairy Goat Field Day Proceedings}, volume = {19}, year = {2004}, month = {April 24, 2004}, pages = {188}, abstract = {Twenty-four Boer crossbred yearling wethers (23.5 {\textpm} 2.31 kg initial BW) were used to determine effects of stepwise increases in dietary level of Eastern red cedar (Juniperus virginiana) foliage (CF), compared with a constant, relatively high level and subsequent availability of low-quality forage, on present and later consumption of CF. Animals were penned individually in Phases 1 (8 wk) and 3 (2 wk) and during Phase 2 (6 wk) wethers were kept in a pasture not containing cedar trees and were fed wheat hay. In Phase 1 a concentrate-based diet (CBD, 12.6\% CP and 35.5\% NDF) was offered at approximately 85\% of the maintenance energy requirement alone (Control) or with weekly stepwise (Step) increases in level of substitution of CF for CBD (0, 1.25, 2.5, 5, 10, 15, 20, and 25\% in wk 1-8, respectively; DM basis) or substitution of 25\% CF in wk 2-8 (Set). In Phase 3 (2 wk), all wethers were offered the diet of 75\% CBD and 25\% CF as previously, without or with separate free-choice access to low-quality grass hay. CF was harvested weekly, refrigerated and hand-mixed with CBD prior to feeding. In Phase 1, intake of CF as a percentage of that offered was greater (P < 0.05) for Step vs. Set in wk 3-8 (wk 3: 86 and 48; wk 4: 89 and 56; wk 5: 90 and 71; wk 6: 96 and 81; wk 7: 93 and 63; wk 8: 96 and 84), although CF intake as g/day was greater (P < 0.05) for Set vs. Step in all but wk 7 and 8. In Phase 3, CBD intake was similar among treatments, and hay intake when offered averaged 149, 134 and 124 g/day for Step, Set and Control, respectively. For wethers not receiving hay, CF intake as g/day for Step was greatest among treatments (P < 0.05) but was not different from treatments with offered hay (67, 37, 30, 55, 53 and 56 g/day for Step, Set and Control without and with hay, respectively; SE = 7.1). Similarly, CF intake as a percentage of that offered ranked (P < 0.05) Step > Set > Control without hay, but was not different between Step without hay and treatments with hay (78, 41, 34, 61, 57 and 60\% for Step, Set and Control without and with hay, respectively; SE = 7.6). Concentrations of various blood constituents at the end of Phases 1 and 3 did not indicate adverse health effects of CF consumption. In conclusion, gradual increases in dietary level of CF deserve further research as a potential means to elevate present and future CF consumption, with attention also directed to effects of type and level of other feedstuffs offered.}, keywords = {Boer crossbred wether goats, eastern red cedar, exposure methods}, author = {Animut, G. and Goetsch, A.L. and Richard E. Estell and Merkel, R.C. and Dawson, L.J. and Sahlu, T. and Puchala, R.} } @article {50625, title = {Effects of methods of exposure to Eastern red cedar foliage on cedar consumption by Boer crossbred wether goats}, journal = {Small Ruminant Research}, volume = {54}, number = {3}, year = {2004}, month = {September 1, 200}, pages = {197-212}, abstract = {Twenty-four crossbred Boer yearling wethers (23.5 {\textpm} 2.31 kg initial BW) were used to determine effects of stepwise increases in dietary level of Eastern red cedar (Juniperus virginiana) foliage (CF), compared with a constant relatively high level and subsequent availability of low-quality forage, on present and later consumption of CF. Animals were penned individually in Phases 1 (8 wk) and 3 (2 wk), and during Phase 2 (6 wk) wethers were kept in a pasture not containing cedar trees and were fed wheat hay. In Phase 1, a concentrate-based diet (CBD, 12.6\% CP and 35.5\% NDF) was offered at approximately 85\% of the maintenance energy requirement alone (Control) or with weekly stepwise (Step) increases in level of substitution of CF for CBD (0, 1.25, 2.5, 5, 10, 15, 20, and 25\% in wk 1-8, respectively; DM basis) or substitution of 25\% CF in wk 2-8 (Set). In Phase 3 (2 wk), all wethers were offered the diet of 75\% CBD and 25\% CF as previously, without or with separate free-choice access to low-quality grass hay. CF was harvested weekly, refrigerated and hand-mixed with CBD prior to feeding. In Phase 1, intake of CF as a percentage of that offered was greater (P < 0.05) for Step vs. Set in wk 3-8 (wk 3: 86 and 48; wk 4: 89 and 56; wk 5: 90 and 71; wk 6: 96 and 81; wk 7: 93 and 63; wk 8: 96 and 84), although CF intake as g/day was greater (P < 0.05) for Set vs. Step in all but wk 7 and 8. In Phase 3, CBD intake was similar among treatments, and hay intake when offered averaged 149, 134 and 124 g/day for Step, Set and Control, respectively. For wethers not receiving hay, CF intake as g/day for Step was greatest among treatments (P < 0.05) but was not different from treatments with offered hay (67, 37, 30, 55, 53 and 56 g/day for Step, Set and Control without and with hay, respectively; SE = 7.1). Similarly, CF intake as a percentage of that offered ranked (P < 0.05) Step > Set > Control without hay, but was not different between Step without hay and treatments with hay (78, 41, 34, 61, 57 and 60\% for Step, Set and Control without and with hay, respectively; SE = 7.6). Concentrations of various blood constituents at the end of Phases 1 and 3 did not indicate adverse health effects of CF consumption. In conclusion, gradual increases in dietary level of CF deserve further research as a potential means to elevate present and future CF consumption with attention also directed to effects of type and level of other feedstuffs offered.}, keywords = {eastern red cedar, feed intake, goats, methods of exposure}, url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6TC5-4BG8V3T-3-K\&_cdi=5161\&_user=1496926\&_orig=browse\&_coverDate=09\%2F30\%2F2004\&_sk=999459996\&view=c\&wchp=dGLbVzb-zSkWW\&md5=d6a246153066668c3324bf74bafee0be\&ie=/sdarticle.pdf}, author = {Animut, G. and Goetsch, A.L. and Merkel, R.C. and Detweiler, G. and Dawson, L.J. and Puchala, R. and Sahlu, T. and Richard E. Estell} } @conference {50626, title = {Endophytic fungi associated with shrubs and grasses of the northern Chihuahuan Desert and a potential role in drought tolerance}, booktitle = {Annual Meeting, Canadian Botanical Association}, year = {2004}, month = {June 26-30, 2004}, pages = {p. 10}, address = {Winnipeg, Manitoba, Canada }, abstract = {Native grasses and shrubs of the northern Chihuahuan Desert are predominantly colonized by dark septate endophytes. Methods using stains that target fungal chitin and internal lipids with high-magnification, light microscopy and scanning electron microscopy revealed a much greater incidence of colonization than was previously thought. In-vitro-regenerated plants from meristematic stem cells were also found to be colonized with the same fungi observed in plants from native populations. Originally thought to be restricted to roots, they are conspicuously present in meristems, sieve elements, xylem vessels of roots and leaves and in photsynthetic cells and stomata. Differing from pathogens and mycorrhizal fungi that have localized patterns of colonization, they systemically inhabit the entire apoplastic network of below- and aboveground organs. They encapsulate host cell protoplasts and are vertically transmitted by seed. Hyphal networks and biofilms that encapsulate all cells and tissues of micropropagated and native plants prevent their direct exposure to harsh external environments. The intimate nature of the association with all plant cells and organs indicates that these native desert shrubs and grasses function as composite plant-fungus organisms. A potential role in managing basic physiological processes that positively enhance plant survival in arid ecosystems is suggested.}, keywords = {Chihuahuan Desert, colonization, endophytes, fungi}, author = {J.R. Barrow and Aaltonen, R.E. and P. Osuna-Avila and I. Reyes-Vera} } @proceedings {50642, title = {Exploitation of multi-angle data from CHRIS on PROBA: First results from the Jornada Experimental Range}, year = {2004}, month = {2004}, abstract = {This study reports on work to assess the utility of multi-angle data in providing measures of the physical structure and composition of desert grasslands. The target is in the United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Jornada Experimental Range (JER), Las Cruces, New Mexico, USA. The JER is a CHRIS/Proba Core Site. The approaches followed include multi-angle image ratios, bidirectional reflectance distribution function (BRDF) model inversion - Li-Ross kernel-driven and the nonlinear simple geometric model (SGM) - and the structural scattering index (SSI). The data used are from the Compact High-Resolution Imaging Spectrometer (CHRIS) flown on the European Space Agency{\textquoteright}s Project for On-Board Autonomy (Proba) satellite launched on October 22, 2001, into a sunsynchronous, elliptical, low Earth orbit. The results indicate that there is canopy structure information in angular ratio images where spatial variation corresponds with mean plant size. The SSI did not behave as expected with high values corresponding to sparsely vegetated areas. SGM fits to data were good (mode RMSE < 0.01) and produced mostly reasonable parameter values with meaningful spatial distributions.}, author = {M. Chopping and Andrea S. Laliberte and A. Rango} } @conference {50649, title = {Effects of {\~a}-terpinene, terpinolene, {\'a}-copaene, and {\'a}-terpinene on consumption of alfalfa pellets by sheep}, booktitle = {2004 Joint Annual Meeting, American Dairy Science Association/American Society of Animal Science/Poultry Science Association}, volume = {Vol. 82 (Suppl. 1)}, year = {2004}, month = {July 25, 2004}, pages = {34}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, address = {St. Louis, MO}, abstract = {Secondary chemistry influences shrub consumption by free-ranging ruminants. However, effects of many specific terpenes on herbivory have not been examined. Four experiments were conducted to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either {\~a}-terpinene, terpinolene, {\'a}-copaene, or {\'a}-terpinene at one of five concentrations in an ethanol carrier. Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (0.64 kg{\textperiodcentered}lamb-1{\textperiodcentered}d-1, DM basis), and consumption was measured during a 20-min interval for 5 d. Lambs were adapted to handling and individual pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 3.9\% of BW (DM basis). A day effect (P <0.02) was detected for intake with {\~a}-terpinene (P <0.0001 for both linear and quadratic contrasts). A treatment effect (P <0.02) was observed for {\'a}-copaene, with intake on the 2X treatment lower than other treatments. No effect of terpinolene or {\'a}-terpinene on intake was observed during the 20-min interval. None of the chemicals tested were strongly related to intake of alfalfa pellets by lambs under the conditions of this study.}, keywords = {alfalfa pellet intake, intake, lambs, sheep, terpenes}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50667, title = {Experimental definition of resilience for state-and-transition models}, booktitle = {57th Annual Meeting, Society for Range Management}, year = {2004}, month = {January 24-30, 2}, pages = {142}, address = {Salt Lake City, UT}, abstract = {Limited management resources must increasingly be targeted to those parts of the landscape that have the greatest degradation risk and recovery potential. State and transition models have the potential tohelp identify these areas. Effective application of these models requires an understanding of the ecological properties and processes that determine resistance to change and resilience (capacity for recovery). Few data are currently available. In 1997 we established a long-term landscape-scale experiment designed to (1) identify resilience indicators based on relative recovery rates for different soil and vegetation indicators, and (2) determine the extent to which these relationships can be generalized across soils. Three types of disturbance (ORV tracks and trampling by humans and horses) were applied to five soils in southern New Mexico. Response variables included vegetation and lichen cover and composition, soil aggregate stability, soil surface roughness, infiltration capacity and penetrometer resistance. Both resistance and resilience varied with both disturbance and soil type. Vegetation indicators generally showed lower resistance (greater change) and higher resilience (more rapid recovery) during the first 6 years of the study than the soil indicators for most disturbance and soil types. These results suggest that soil indicators may reveal long-term disturbance effects that are not reflected in short-term vegetation responses. Both the long-term, cumulative effects of soil property changes on subsequent resistance and resilience and the role of contiguous site effects need to be considered in the development state and transition models.}, keywords = {degradation, models, resilience, state-and-transition}, author = {Jeffrey E. Herrick and Jayne Belnap and Brandon T Bestelmeyer and S.B. Bird and Joel R. Brown and Kris Havstad and A.J. Tugel and Justin Van Zee} } @article {50675, title = {Effects of pocket gophers on desert soils and vegetation}, journal = {Journal of Arid Environments}, volume = {58}, number = {2}, year = {2004}, month = {July 1, 2004}, pages = {155-166}, abstract = {

The effects of pocket gophers (Geomyidae) on soils and vegetation were studied on Chihuahuan Desert and Sonoran Desert catenas for comparison with the effects of pocket gophers on soils and vegetation in mesic environments. Two species of gophers, Thomomys bottae and T. umbrinus, ejecta mounds were located on upper slopes of piedmonts where runoff from mountains increase soil moisture. Geomys arenarius ejecta mounds were restricted to small valley bottoms on ridge and valley mesa topography. Soil bulk density of ejecta mound soils was lower than undisturbed soil at the Chihuahuan Desert sites but not at the Sonoran Desert site. Significantly higher annual plant cover were recorded only for ejecta mounds of the Chihuahuan Desert piedmont. The effects of pocket gopher burrowing differed between the species, with G. arenarius sites showing greater extent of soil disturbance at a local scale, but effects of these disturbances on desert soils vegetation are dependent upon the properties of the undisturbed soil. These findings of limited impacts of burrowing on soil chemistry contrast with the situation in more mesic areas.

}, keywords = {bulk density, desert, geomyidae, pocket gophers, soil, topography, vegetation}, doi = {10.1016/j.jaridenv.2003.08.001}, url = {/files/bibliography/04-074.pdf}, author = {G. I. H. Kerley and Walter G. Whitford and F. R. Kay} } @article {50692, title = {Effects of intense, short-duration grazing on microtopography in a Chihuahuan Desert grassland}, journal = {Journal of Arid Environments}, volume = {56}, number = {3}, year = {2004}, month = {February 1, 2004}, pages = {383-393}, abstract = {

We studied the effect of three consecutive years of short duration (\<48 h per year), and intense grazing (20{\textquoteright}40 yearling cows per hectare) on soil surface microtopography in a Chihuhuan Desert grassland. We also studied the effects of shrub removal plus grazing on microtopography. Microtopography was measured in 18 plots (treatments). Treatments were a combination of two factors: (1) three levels of grazing (winter-grazed, summer-grazed, and not grazed), and (2) two levels of habitat structure (shrubs-removed and shrubs-intact). Mesquite (Prosopis glandulosa) shrubs were removed from half of the plots (nine out of 18 plots). The average height of the micromounds, the average depths of intermound depressions, and the number of micromounds were significantly reduced on the grazed plots. Shrub removal had no significant effect on the height of the micromounds or the depth of the intermound depressions of ungrazed plots. There were significant differences in average micromound heights and intermound microdepression depths attributable to the season of grazing. Microtopography was significantly reduced on grazed plots from which shrubs were removed, compared to ungrazed plots, and grazed plots with shrubs present. Grass canopy reduction, and destruction of the micromound structure in a short duration, plus intense grazing results in erosion of micromounds and in-filling of intermound depressions. The loss of microtopography coupled with reduction in vegetation height and cover resulting from short-duration intense grazing by cattle exposed soils to an increased risk of soil erosion Destruction of the micromound/microdepression topography by cattle changes the spatial patterns of water infiltration, and may homogenize nutrients in desert grasslands.

}, keywords = {cattle, grazing, Hoof-action Microtopography index, Microdepressions, Micromounds, wind erosion}, doi = {10.1016/S0140-1963(03)00062-4}, url = {/files/bibliography/04-073.pdf}, author = {M. S. Nash and E. Jackson and Walter G. Whitford} } @conference {50719, title = {The effects of altered precipitation patterns on ecosystem responses in a desert rangeland}, booktitle = {4th International Conference on Applications of Stable Isotope Techniques to Ecological Studies}, year = {2004}, month = {April 19, 2004}, pages = {79}, abstract = {Many desert regions are characterized by seasonally dominated rainfall regimes. Global climate change models predict regional changes in average seasonal precipitation, but few models address how changes in the delivery of precipitation within a season will affect ecosystem responses. In the southwestern US, summer rainfall is highly unpredictable and punctuated by intervening dry periods of variable lengths. These patterns of precipitation pulses and subsequent dry periods may differentially affect water use and net ecosystem carbon exchange, depending on the ability of various ecosystem components (e.g., plants, soil microbes, and biological soil crusts) to respond to increases in water availability and maintain function during soil dry-down. The objective of this study was to examine how a 60-mm increase in summer precipitation (46\% increase relative to mean summer rainfall) applied in two contrasting treatments affected carbon exchange and water use. Eighteen 4x6-m plots containing both a mesquite shrub (Prosopis glandulosa) and scattered black grama grass (Bouteloua eriopoda) were assigned to one of three watering treatments (n=6): ambient precipitation (controls), ambient plus frequent, small (5-6 mm) rainfall events applied weekly, and ambient plus infrequent, large (20-24 mm) events applied monthly. Treatments were applied for 12 weeks during summer using deuterium-enriched water. Stable isotope ratios of hydrogen (dD) in plant xylem water and carbon (d13C) in respired CO2 were used to partition water source use and respiratory CO2 flux. The dD of mesquite xylem sap indicated that mesquite was able to use water from both small and large precipitation events, while control plants accessed water from deep within the soil profile. Changes in soil moisture, mesquite predawn water potentials, and mesquite stem elongation were highest in monthly watered plots, intermediate in weekly plots, and lowest in control plots. Although large events appeared to favor carbon gain of C3 shrubs, biological soil crust communities may have taken advantage of smaller more frequent events. Daytime measurements of net ecosystem carbon exchange on subplots containing soil, plant roots, and biological soil crusts indicated control and monthly plots were losing CO2 to the atmosphere, while weekly plots were acquiring CO2. After application of 2 mm of water to all plots, net uptake of CO2 was observed in all plots, but the magnitude of crust photosynthetic response was greatest in weekly watered plots. Keeling plot analyses of the d13C of respired CO2 during dark hours indicated that the contribution from different sources (roots, microbes, and soil crusts) varied with watering treatment. Small frequent rainfall appeared to promote the proportional contribution of microbial respiration or C4 roots to total respiratory flux, while infrequent large rainfall resulted in a greater proportion of CO2 originating from biological soil crusts or C3 root activity. Control plots that had received little ambient rainfall had more negative d13C values, indicating another potentially deeper C3 dominated source of respired CO2.}, keywords = {altered, carbon exchange, desert rangeland, ecosystem responses, precipitation patterns, precipitation pulses, water use}, author = {K. A. Snyder and Cable, J.M. and T. Huxman and Connie J. Maxwell} } @article {50722, title = {Extensive summer water pulses do not necessarily lead to canopy growth of Great Basin and northern Mojave Desert shrubs}, journal = {Oecologia}, volume = {141}, number = {2}, year = {2004}, month = {October 1, 2004}, pages = {325-334}, abstract = {Plant species and functionally related species groups from arid and semiarid habitats vary in their capacity to take up summer precipitation, acquire nitrogen quickly after summer precipitation, and subsequently respond with ecophysiological changes (e.g., water and nitrogen relations, gas exchange). For species that respond ecophysiologically, the use of summer precipitation is generally assumed to affect long-term plant growth and, thus, alter competitive interactions that structure plant communities and determine potential responses to climate change. We assessed ecophysiological and growth responses to large, short-term irrigation pulses over one to three growing seasons for several widespread Great Basin and northern Mojave Desert shrub species: Chrysothamnus nauseosus, Sarcobatus vermiculatus, Atriplex confertifolia, and A. parryi. We compared control and watered plants in nine case studies that encompassed adults of all four species, juveniles for three of the species, and two sites for two of the species. In every comparison, plants used summer water pulses to improve plant water status or increase rates of functioning as indicated by other ecophysiological characters. Species and life history stage responses of ecophysiological parameters were consistent with several previous short-term studies. However, use of summer water pulses did not affect canopy growth in eight out of nine comparisons despite the range of species, growth stages, and site conditions. Summer water pulses affected canopy growth only for C. nauseosus adults. The general lack of growth effects for these species might be due to close proximity of groundwater at these sites, colimitation by nutrients, or inability to respond due to phenological canalization. An understanding of the connections between short-term ecophysiological responses and growth for different habitats and species is critical for determining the significance of summer precipitation for desert community dynamics.}, keywords = {canopy growth, desert community, Great Basin, irrigation, Mojave Desert, summer water pulses}, url = {http://www.springerlink.com/media/eflppvlyxlhh19vhhl5x/contributions/j/u/l/f/julfeguq25yfl0cd.pdf}, author = {K. A. Snyder and L.A. Donovan and J. James and Tiller, R.L. and J. H. Richards} } @conference {50723, title = {Ecological function of the North Caspian Sea: Production, nutrients and pollutants}, booktitle = {89th Annual Meeting, Ecological Society of America}, year = {2004}, month = {August 1, 2004}, pages = {Abstract p. 500}, address = {Portland, OR}, abstract = {The Caspian Sea is the largest inland water body on earth (386,400 km2, maximum depth 1025 m). With its long history of oil and industrial development, the Caspian is often regarded as severely polluted and ecologically degraded. The North Basin of the Caspian Sea is a large (25\% of the Caspian Sea surface area), shallow (median depth 4 m), well-mixed, slightly brackish estuary fed by the Volga and Ural Rivers. We have synthesized historical Soviet data, post-Soviet data and data from a recent sampling cruise in September 2003 to investigate the current ecological status of the North Basin of the Caspian Sea. The Volga River supplies approximately 80\% of the water input to the entire Caspian Sea and is the major source of nutrients and pollutants to the North Basin. The North Basin of the Caspian Sea is less polluted with heavy metals, pesticides and probably hydrocarbons than commonly assumed and less polluted now than during the Soviet era. Pollutant levels in organisms such as fish and seals are generally lower or comparable to those of other large seas and lakes, such as the Mediterranean, Black, and Baltic Seas. Autochthonous primary production supplies the majority of the organic carbon inputs with more than 50\% provided by phytoplankton (14-22 TG C /yr) and about 4-9 TG C /yr added by the Volga River. Primary production in the North Basin is usually phosphorus-limited and significant oxygen depletion seldom develops. Commercial fish stocks in the North Caspian have declined significantly in recent years due to overfishing. The Caspian Sea supplies about 90\% of the world{\textquoteright}s caviar but less than 1\% of the remaining Beluga sturgeon (Huso huso) are mature breeders. Accurate, independent information on the size and age class distribution of valuable sturgeon species and the Caspian Seal are not available.}, keywords = {current ecological status, North Caspian Sea, nutrients, pollutants, production}, author = {S. Tartowski and T.J. Butler and Lychagin, M.Y. and V. Bashkin and Sisengalieva, G. and Yergaliyev, T.} } @conference {50739, title = {Effects of method of exposure of crossbred Boer wether goats to Eastern red cedar foliage on cedar consumption}, booktitle = {Joint Annual Meeting of the American Dairy Science Association, American Society of Animal Science, and the Mexican Association of Animal Production}, volume = {81}, number = {Suppl. 1}, year = {2003}, month = {June 22-26, 2003}, pages = {324-325}, address = {Phoenix, AZ}, abstract = {This study was conducted to determine effects on present and future consumption of Eastern red cedar (Juniperus virginiana) foliage (CF) by goats of stepwise increases in dietary level of CF compared with a constant, relatively high-level and subsequent availability of low-quality forage. Twenty-four yearling wethers (23.5 {\textpm} 2.31 kg initial BW) were penned individually in Phases 1 and 3. In Phase 1 (8 wk), a concentrate-based diet (12.6\% CP and 35.5\% NDF) was offered at approximately 85\% of the maintenance energy requirement alone (Control) or with weekly stepwise (Step) increases in substitution of CF for concentrate (0, 1.25, 2.5, 5, 10, 15, 20, and 25\% in wk 1-8, respectively; DM basis) or substitution of 25\% CF in wk 2-8 (Set). Wethers grazed grass pasture in Phase 2 (6 wk). In Phase 3 (2 wk), all wethers were offered the 75\% concentrate, 25\% CF diet, without or with separate free-choice offering of prairie hay. CF was harvested weekly from male trees and refrigerated; CF and concentrate were hand-mixed prior to feeding. In Phase 1, average total DMI was similar among treatments. Intake of CF as a percentage of that offered was greater (P < 0.05) for Step vs Set in wk 3-8 (wk 3: 86 and 48; wk 4: 89 and 56; wk 5: 94 and 71; wk 6: 96 and 81; wk 7: 93 and 63; wk 8: 96 and 84), although CF intake as g/d was greater (P > 0.05) for Set vs Step in all but wk 7 and 8. In Phase 3, concentrate intake was similar among treatments, and hay intake when offered averaged 149, 134, and 124 g/d for Step, Set, and Control, respectively. For wethers not receiving hay, CF intake as g/d for Step was greatest among treatments (P < 0.05) but was not different from treatments offered hay (67, 37, 30, 55, 53, and 56 g/d for Step, Set, Control, Step+hay, Set+hay, and Control+hay, respectively; SE = 7.1). Similarly, CF intake as a percentage of offered CF ranked (P < 0.05) Step > Set > Control without hay, but was not different between Step without hay and treatments with hay (78, 41, 34, 61, 57, and 60\% for Step, Set, Control, Step+hay, Set+hay, and Control+hay, respectively; SE = 7.6). In conclusion, gradual increases in dietary level of CF deserve further research as a potential means of elevating present and future CF consumption, with attention also directed to type and level of other feedstuffs offered.}, author = {Animut, G. and Goetsch, A.L. and Merkel, R.C. and Detweiler, G. and Dawson, L.J. and Puchala, R. and Sahlu, T. and Richard E. Estell} } @article {50753, title = {The effects of termites and straw mulch on soil nitrogen in a creosotebush (Larrea tridentata)-dominated Chihuahuan Desert ecosystem}, journal = {Journal of Arid Environments}, volume = {53}, number = {1}, year = {2003}, month = {January 1, 2003}, pages = {15-20}, abstract = {

The effects of organic matter (wheat straw) and subterranean termites on concentrations of soil nitrogen were measured on insecticide-treated plots to eliminate termites and by adding straw mulch to insecticide-treated and insecticide-untreated plots. Soil nitrogen was significantly higher, 435 mg g (-1 power) soil at 0-5 cm depth, on plots with no termites than on plots with termites (340 mg g (-1 power) soil). There were no differences in total soil nitrogen at soil depths of 5-10 cm. Soil nitrogen was higher in soils with termites than in soils with termites excluded on straw-amended plots. On the plots without straw amendments, total soil nitrogen was higher in soils without termites than in soils with termites present. Termites had no significant effect on total soil nitrogen under shrub canopies in comparison with intercanopy soils. The addition of straw mulch did not result in higher soil nitrogen content in soils without termites. Termites were more important as effectors of soil nitrogen than addition of organic matter in the form of wheat straw.

}, doi = {10.1006/jare.2002.1031}, author = {Michael F. Brown and Walter G. Whitford} } @article {50755, title = {The effects of termites and straw mulch on soil nitrogen in a creosotebush (Larrea tridentata) dominated Chihuahuan Desert Ecosystem}, journal = {Journal of Arid Environments}, volume = {53}, year = {2003}, note = {//NMSU//LTER IV//}, month = {2003}, pages = {15-20}, abstract = {

The effects of organic matter (wheat straw) and subterranean termites on concentrations of soil nitrogen were measured on insecticide-treated plots to eliminate-termites and by adding straw mulch to insecticide-treated and insecticide-untreated plots. Soil nitrogen was significantly higher, 435 mg g-1 soil at 0-5 cm depth on plots with no termites than on plots with termites (340 mg g-1 soil). There were no differences in total soil nitrogen at soil depths of 5-10 cm. Soil nitrogen was higher in soils with termites than in soils with termites excluded on straw-amended plots. On the plots without straw amendments, total soil nitrogen was higher in soils without termites than in soils with termites present. Termites had no significant effect on total soil nitrogen under shrub canopies in comparison with intercanopy soils. The addition of straw mulch did not result in higher soil nitrogen content in soils without termites. Termites were more important as effectors of soil nitrogen than addition of organic matter in the form of wheat straw. \©2002 Elsevier Science Ltd.

}, keywords = {article, articles, Chlordane, termite, journal, journals, pesticide, Chlordane, pesticide, termites, soil nitrogen, termites, termite, Chlordane, termite, pesticide, termites, soil nitrogen}, doi = {10.1006/jare.2002.1031}, url = {files/bibliography/03-JrnlofArdEnvirnmnts-Whitford.pdf}, author = {Michael F. Brown and Walter G. Whitford} } @proceedings {50754, title = {Environmental drivers and monitoring of rangelands}, year = {2003}, month = {July 26-August 1}, pages = {668-674}, address = {Durban, South Africa}, abstract = {Environmental drivers are factors that cause measurable changes in properties of biological communities. Examples of drivers can include environmental factors such as rainfall variability and available soil nitrogen, management factors such as livestock grazing practices and prescribed burning, government factors such as tax laws and environmental policies, and societal factors such as attitudes regarding property rights and prevailing public values. It is difficult to identify the impact of specific drivers on specific properties at specific times since drivers seldom operate independently or singularly. Impacts of some drivers, especially nonecological, may not be readily quantifiable. Yet, any interest in understanding how systems will respond to specific drivers, such as a grazing management practice, requires monitoring of system dynamics and pertinent environmental drivers. For example, risk assessments and adaptive management analyses both require understanding linkages between environmental drivers and various management options on ecological properties of managed systems. Any type of predictive management strategy for proposing future options would require an understanding of biological responses to environmental drivers. Though our abilities to generate accurate predictions are currently limited, conceptual models of system responses to drivers are improving. Continued incorporation and refinement of our understanding and monitoring effects and interactions of different drivers will contribute to improvements in these predictive capacities. It is important to remember that we are developing monitoring systems for the future, as well as for today.}, url = {/files/bibliography/03-031.pdf}, author = {Joel R. Brown and Kris Havstad} } @article {50761, title = {Effective aerodynamic roughness estimated from airborne laser altimeter measurements of surface features}, journal = {International Journal of Remote Sensing}, volume = {24}, number = {7}, year = {2003}, note = {ARIS entry by Beltsville.}, month = {April 10, 2003}, pages = {1545-1558}, abstract = {

Aerodynamic roughness length (z0) and displacement height (d0) are important surface parameters for estimating surface fluxes in numerical models. These parameters are generally determined from wind flow characteristics using logarithmic wind profiles measured at a meteorological tower or by balloon release. It would be an advantage to use measurements of land surface characteristics instead of wind flow characteristics to estimate the z0 and d0 for large areas. Important land surface characteristics are the size and distribution of roughness elements (obstacles). This research evaluates the use of high resolution laser altimeter data to obtain these land surface characteristics. Data were collected at the US Department of Agriculture, Agriculture Research Service (USDA-ARS), Jornada Experimental Range in southern New Mexico, USA over a coppice dune dominated area. These dunes are covered by honey mesquite (Prosopis glandulosa Torr.) with flat and mostly bare interdunal areas. For this analysis, three 450 m laser transects with a 2 cm measurement interval were used. The distribution and size of dunes were calculated from these laser transects and used to compute z0. Analysis gave an average z0=4.3 cm and d0=70 cm for the three laser transects, which compares to z0=7+4cm and d0=98+48 cm calculated from wind profile data measured at a 10 m tower near the laser transects. These results show that the estimation of z0 and d0 for a complex terrain is possible using simple land surface features computed from high resolution laser altimeter data.

}, keywords = {aerodynamic roughness, airborne laser altimeter, measurements, surface features}, doi = {10.1080/01431160110115997}, url = {/files/bibliography/03-026.pdf}, author = {De Vries, A. C. and William P. Kustas and Jerry Ritchie and Klaassen, W. and Menenti, M. and A. Rango and J.H. Prueger} } @conference {50852, title = {Early forecasts of snowmelt runoff using SNOTEL data in the upper Rio Grande basin}, booktitle = {EOS Transactions, American Geophysical Union}, volume = {83}, number = {47}, year = {2003}, month = {11/2003}, pages = {F540}, address = {San Francisco, CA}, abstract = {

Forecasts using SNOTEL data on November 1 and December 1 gave the best estimates of spring snowmelt runoff volumes almost as frequently as forecasts on March 1 and April 1 for the Upper Rio Grande basin in Colorado during 1983-2001. Forecasts for 2002, a record drought year, greatly overestimated flow volumes regardless of prediction month. Attempts at improving predictions using the El Nino/La Nina Southern Oscillation Index were not successful

}, url = {files/bibliography/Rango2003-03.pdf}, author = {D. DeWalle and Eismeier, J.A. and A. Rango} } @proceedings {50763, title = {Early forecasts of snowmelt runoff using SNOTEL data in the upper Rio Grande Basin}, year = {2003}, month = {April 21-25, 200}, pages = {17-22}, address = {Scottsdale, AZ}, abstract = {Forecasts using SNOTEL data on November 1 and December 1 gave the best estimates of spring snowmelt runoff volumes almost as frequently as forecasts on March 1 and April 1 for the upper Rio Grande basin in Colorado during 1983-2001. Forecasts for 2002, a record drought year, greatly overestimated flow volumes regardless of prediction month. Attempts at improving predictions using the El Nino/La Nina Southern Oscillation Index were not successful.}, author = {D. DeWalle and Eismeier, J.A. and A. Rango} } @article {50765, title = {Effects of fire season and intensity on Prosopis glandulosa Torr. var. glandulosa}, journal = {International Journal of Wildland Fire}, volume = {12}, number = {2}, year = {2003}, month = {June 1, 2003}, pages = {147-157}, abstract = {In pyrogenic ecosystems, responses of resprouting woody vegetation may depend more on fire season than intensity. I explored this hypothesis by examining fire season and intensity effects on response of Prosopis glandulosa, a resprouting shrub in Chihuahuan Desert grasslands of the southwestern United States. Clipping, as well as low and high intensity fires (natural and added fuels, respectively), was applied during the 1999 growing season and the 2000 dormant season. Both fire season and intensity affected shrub responses. Numbers of resprouts were 16\% greater and heights were 8\% taller after dormant season than growing season treatments of fire and clipping combined. Height and resprout number decreased with increased fire intensity. Fire season and intensity effects on canopy area and stem growth were generally not detected. My results do not support the hypothesis. Instead, fire season and intensity use two different mechanisms that influence shrub responses. Prosopis glandulosa has the potential to respond more after dormant season than growing season fires as determined by carbohydrate availability in underground organs at the time of fire. However, realization of this potential is contingent on fire intensity as influenced primarily by fuel amount. In turn, fire intensity will determine the amount and duration of heat penetration into soils and thus the amount of damage to growing points of underground organs.}, url = {/files/bibliography/03-024.pdf}, author = {Drewa, P.B.} } @conference {50768, title = {Effect of previous exposure of sheep to monoterpene odors on intake of alfalfa pellets treated with camphor or alpha-pinene}, booktitle = {Joint Annual Meeting of the American Dairy Science Association, the American Society of Animal Science, and the Mexican Association of Animal Production}, volume = {81}, number = {Suppl. 1}, year = {2003}, month = {June 22-26, 2003}, pages = {353}, address = {Phoenix, AZ}, abstract = {Lambs were exposed to aromas of two monoterpenes that had previously been found to decrease intake to determine if exposure during feeding modified effects of these terpenes on subsequent intake. Two experiments were conducted using a split-plot design. Thirty-six ewe lambs (mean BW = 23.1 and 42.2 kg in Exp. 1 and 2, respectively) were group-fed alfalfa pellets (4\% of BW, DM basis) in enclosed portable buildings (3.0 x 3.7 m) for 2 h each morning for 56 d. Nine lambs were randomly assigned to each of four buildings, and the appropriate chemical (25 g of camphor in Exp. 1 or 50 ml of alpha-pinene in Exp. 2) was placed in a mesh-covered container in the center of the feeder in two buildings immediately before feeding (two buildings served as controls). After the 8-wk exposure period, lambs were individually fed alfalfa pellets (640 g, DM basis) for 20 min each morning for 10 d (5-d adaptation, 5-d intake measurement) in a metabolism building. Treatments were sprayed on alfalfa pellets at levels representing the concentration of that chemical in Flourensia cernua or at 10-fold that concentration. Controls received ethanol carrier only. Lambs were fed in three groups (n = 12), stratified such that one lamb from each building was placed on each treatment in each group. Lambs were housed as one group and fed alfalfa pellets at 5\% of BW (DM basis) except during the 20-min tests. No day effect was detected for intake with either chemical (P> 0.05); therefore, data for collection periods were pooled across day. Exposure to the volatile aroma for 8 wk had no effect on intake during the 10-d interval for either monoterpene (P> 0.05). Moreover, intake during the 10-d interval was not affected by treatment concentration (P> 0.05). Neither concentration of the terpene applied to feed nor previous exposure to the volatile aroma from camphor or alpha-pinene altered feed intake under the conditions of this study.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {50776, title = {Extreme events as shaping physiology, ecology, and evolution of plants: toward a unified definition and evaluation of their consequences}, journal = {New Phytologist}, volume = {160}, year = {2003}, note = {//NMSU,USDA//LTER IV//}, month = {2003}, pages = {21-42}, abstract = {

The paper considers how extreme events, particularly climatic and biotic, affect the physiology, development, ecology and evolution of organisms, focusing on plants. It is proposed that extreme events need to be defined in terms of organismal responses of acclimation and of de-acclimation or hysteresis. From this a number of hypotheses are developed, including that fitness effects of extreme events occur primarily during recovery. Evidence is reviewed that selection is virtually absent except during extreme events on the evolutionary time scale. Extreme events drive strong directional selection, even to trait fixation and speciation. A number of new tools are described, both conceptual and technological, that are now at hand or that merit rapid development.

}, keywords = {acclimation, article, articles, biogeographic limits, climate change, evolution, extreme events, journal, journals, natural selection, neutrality, physiological ecology}, doi = {10.1046/j.1469-8137.2003.00866.x}, url = {files/bibliography/JRN00384.pdf}, author = {V. P. Gutschick and H. BassiriRad} } @proceedings {50780, title = {Evaluation of the health status of rangeland ecosystems}, volume = {23}, year = {2003}, month = {December 1, 2003}, pages = {22-30}, address = {Aguascalientes, Mexico}, abstract = {Rangeland health refers to the maintenance of complex ecological processes during a particular period of time. A manual, {\textquoteright}Interpreting Indicators of Rangeland Health,{\textquoteright} was developed with the objective of providing a system for rapidly evaluating rangeland health. This method uses 17 indicators to evaluate three attributes: soil and site stability, hydrologic function and biotic integrity. In Version 3.0, Ecological Site Descriptions and reference sites served as the reference for the evaluation. In Version 4.0, these two options were replaced with a single Ecological Reference Sheet that provides a semi-quantitative description of the normal range of variability for each indicator for areas with similar soils and climate with the potential to support similar types and amounts of vegetation. The ecological reference sheet is completed by a group of experts with a knowledge of the variability in soils, hydrology and biology expected. Once the normal range of variability has been established, the experts must also define the four categories of deviation from the expected for each indicator. In this way, countries that do not have Ecological Sites or Ecological Site Descriptions can use this manual to develop their own reference sheets.}, author = {Jeffrey E. Herrick and Melgoza, A.M. and D.A. Pyke and P. L. Shaver and M. Pellant} } @conference {50787, title = {Ecohydrology and woody plant encroachment: A conceptual framework for evaluating landscape consequences}, booktitle = {2003 Fall Meeting, American Geophysical Union}, year = {2003}, month = {December 8, 2003}, pages = {F320}, address = {San Francisco, CA}, abstract = {Increases in the abundance or density of woody plants in historically semiarid and arid grassland ecosystems have important implications for hydrology, ecology, and society. Using a simplified water-balance model, we propose a framework for conceptualizing how woody plant encroachment is likely to affect components of the water cycle within these ecosystems. In these systems, shrub removal has been proposed as a mechanism for increasing watershed yield, but such increases are likely only in systems with shallow bedrock, riparian systems, or climatic systems where precipitation exceeds potential evapotranspiration for extended periods. In semiarid and arid systems abiotic controls on evaporation overwhelm biotic control of streamflow. In these systems, the predominant effects of woody plant encroachment that promote ecohydrological feedbacks are changes in: infiltration, depth of plant water removal, generation of transient overland flow and near-ground energy budgets that affect the ratio of evaporation (E) to transpiration (T). In these more xeric areas, the ratio of E:T is critical because it indicates the biological use of water which influences landscape structure. Increasing woody plant cover is associated with larger open interspaces; at the landscape scale the differential contribution of canopy versus interspaces may change landscape E:T. Alterations of spatial structure and ecohydrology likely influence other biogeochemical processes, such as carbon cycling. At the landscape scale, total respiration depends on the magnitude of canopy/interspace respiration flux scaled by the spatial extent of interspaces and canopy space. Canopy respiration is strongly correlated to T, while interspace respiration is largely driven by soil water availability and, therefore, is driven by factors that control E. Resolving the partitioning of E:T should help resolve the net effect of woody plant encroachment on other biogeochemical cycles at the landscape scale. This framework for considering the effects of woody plant encroachment highlights important ecological and hydrological interactions that serve as a basis for predicting other ecological aspects of vegetation change.}, author = {T. Huxman and K. A. Snyder and Wilcox, B.P. and R.L. Scott and David D. Breshears and Small, E.E. and R. B. Jackson and Pockman, W.T. and Hultine, K.R.} } @article {50793, title = {The essential oil composition of Psorothamnus scoparius (A. Gray) Rydb.}, journal = {Journal of Essential Oil Research}, volume = {15}, number = {2}, year = {2003}, month = {March 1, 2003}, pages = {108-111}, abstract = {Psorothamnus scoparius (broom dalea) was collected from the Jornada Experimental Range in south central New Mexico. Current year{\textquoteright}s growth was collected from 10 plants, all found within an approximate 50 m radius of the GPS coordinates N 32 deg 41.286{\textquoteright} and W 106 deg 46.922{\textquoteright} during June 2000. Composite samples were steam distilled, and the essential oil was analyzed using GC with FID and GC/MS. Mass spectra and retention indices were used to identify 65 previously described compounds. Retention indices and EI mass spectra are also provided for 15 unknowns. Gamma-terpinene (22.3\%), para-cymene (14.0\%), and alpha-pinene (9.0\%) were the major constituents of the oil.}, keywords = {broom dalea, composition, essential oil, Psorothamnus scoparius}, url = {/files/bibliography/03-018.pdf}, author = {M.E. Lucero and Richard E. Estell and E.L. Fredrickson} } @conference {50826, title = {An ecohydrological framework for determining the landscape effects of woody plant encroachment}, booktitle = {88th Annual Meeting, Ecological Society of America}, year = {2003}, month = {August 3-8, 2003}, pages = {314}, address = {Savannah, GA}, abstract = {Woody plant encroachment into semiarid and arid systems is a global phenomenon with large potential hydrological and biogeochemical consequences. We considered systems in the southwestern United States (pinyon-juniper, mesquite and creosote) where dramatic changes in physiognomy create potential feedbacks between woody plants and hydrology at the landscape scale. The outcome is a new conceptual framework useful in directing future research and determining broad-scale potential ecological and biogeochemical consequences across a range of ecosystems. Shrub removal has been proposed as a mechanism for increasing water yields, but increased water yields are likely only in systems with shallow bedrock, riparian systems, or mesic systems where precipitation exceeds potential evapotranspiration. In semiarid and arid systems, abiotic controls on evaporation overwhelm biotic control of streamflow. In these systems, the predominant effects of woody plant encroachment that promote ecohydrological feedbacks are changes in: infiltration, depth of plant water removal, generation of transient overland flow and near-ground energy budgets that affect the ratio of evaporation (E) to transpiration (T). In these more xeric areas, the ratio of E:T is critical because it indicates the biological use of water which influences (through feed-forward or feed-back effects) landscape structure. Increasing woody plant cover is associated with larger open interspaces; at the landscape scale, the differential contribution of canopy versus interspaces may change landscape E:T. The alterations of spatial structure and ecohydrology likely influence carbon cycling. At the landscape scale, total respiration depends on the magnitude of canopy/interspace respiration flux scaled by the spatial extent of interspaces and canopy space. Canopy respiration is correlated to T, while interspace respiration is largely driven by soil water availability and, therefore, is driven by factors that control E. Resolving the partitioning of E:T should help resolve the net effect of woody plant encroachment on other biogeochemical cycles at the landscape scale.}, author = {K. A. Snyder and T. Huxman and David D. Breshears and Wilcox, B.P. and Small, E.E. and R.L. Scott and R. B. Jackson and Hultine, K.R.} } @conference {50856, title = {Effects of fire and grazing on vegetation in northern Chihuahuan Desert grasslands}, booktitle = {Society for Range Management, New Mexico Section Winter Meeting}, year = {2002}, note = {Abstract also published for 86th Annual ESA Meeting (129597)}, month = {January 8, 2002}, pages = {5}, address = {Las Cruces, NM}, abstract = {We examined experimentally the effects of growing-season fires and livestock grazing on plant community structure in Chihuahuan Desert grasslands of southern New Mexico. Four 200m x 200m plots were established in each of four different blocks. Treatments were either applied or not applied, resulting in four treatment combinations that were each assigned randomly to one of the four plots within each block. Fires were prescribed in June 1999. Beginning in September 1999, unfenced plots were exposed to 12 months of continuous livestock grazing where utilization was <40\%. Plant cover and frequency were measured immediately before and after treatments using a vertical line point intercept method every 10cm along five 150m-transects within each plot. Cover of Bouteloua eriopoda, the dominant perennial grass, decreased only by 1.22\% following burning but increased 2.20\% in fire-excluded areas. Its frequency decreased 6.49\% and 0.48\% in burned and unburned plots, respectively. After fires, collective perennial forb cover and frequency increased 1.46\% and 3.81\%, respectively, but decreased as much as 4.04\% in unburned plots. Cover and frequency of annuals also increased up to 7.25\% and 20.63\%, respectively, in burned plots but increased as little as 0.3\% in fire-excluded areas. Livestock grazing had a similar effect as fire on only cover of B. eriopoda. Contrary to past research, fire did not result in delayed recovery of B. eriopoda. Additionally, greater increases in cover and frequency of perennial forbs and annuals after burning enhanced overall grassland diversity. Rapid vegetation responses following fire may have been influenced by patterns of precipitation that were equivalent to the average, especially in the immediate post-fire environment.}, author = {Drewa, P.B. and Debra C. Peters and Kris Havstad} } @conference {50857, title = {Effects of camphene, myrcene, caryophyllene oxide and beta-pinene on consumption of alfalfa pellets by sheep}, booktitle = {2002 Joint Meeting, American Society of Animal Science/American Dairy Science Association}, volume = {80}, number = {1}, year = {2002}, month = {July 21-25, 2002}, pages = {331}, address = {Quebec City, Canada}, abstract = {Four experiments were conducted to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (nine lambs/treatment) were individually fed alfalfa pellets sprayed with either camphene, myrcene, caryophyllene oxide, or beta-pinene at one of five concentrations in an ethanol carrier. Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (.64 kg.lamb-1.d-1, DM basis) and consumption was measured during a 20-minute interval for 5 d. Lambs were adapted to handling and individual pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20-minute tests) at a mean total daily intake of 4.7\% of BW (DM basis). Camphene and caryophyllene oxide tended to decrease intake (linear contrasts were P = .0651 and P = .0504, respectively), while myrcene and beta-pinene exerted no effect on consumption of alfalfa pellets by lambs during the 20-minute interval. Camphene and caryophyllene oxide may be involved in the differential herbivory of individual tarbush plants by livestock.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {50859, title = {Effects of four mono- and sesquiterpenes on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {80}, number = {12}, year = {2002}, month = {December 1, 2002}, pages = {3301-3306}, abstract = {Effects of individual terpenes on alfalfa pellet intake by lambs were examined in four experiments. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either camphene, myrcene, caryophyllene oxide, or beta-pinene at one of five concentrations (one terpene per experiment). Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene in tarbush. Terpenes were applied to alfalfa pellets (.64 kg.lamb-1.d-1, DM basis) and consumption wa measured during a 20-min interval for 5 d. Lambs were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 4.7\% of BW (DM basis). Camphene and caryophyllene oxide tended to decrease intake (linear contrasts were P = .0651 and P = .0504, respectively), while myrcene and beta-pinene exerted no effect on consumption of alfalfa pellets by lambs during the 20-min interval. Camphene and caryophyllene oxide may be involved in the differential herbivory of individual tarbush plants by livestock.}, keywords = {alfalfa pellets, consumption, individual terpenes, sheep}, doi = {10.2527/2002.80123301x}, url = {http://jas.fass.org/cgi/reprint/80/12/3301}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50858, title = {Effects of individual terpenes on intake by lambs}, booktitle = {Society for Range Management, New Mexico Section Winter Meeting}, year = {2002}, month = {January 8-10, 20}, pages = {5}, address = {Las Cruces, NM}, abstract = {Effects of individual terpenes on alfalfa pellet intake by lambs were examined. Forty-five lambs were individually fed alfalfa pellets treated with either camphene, myrcene, caryophyllene oxide, or beta-pinene at one of five concentrations. Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on Flourensia cernua leaves. Terpenes were applied to alfalfa pellets (.64 kg DM/lamb) and intake during a 20-minute interval was measured for 5 days. Lambs were adapted to handling and individual pen feeding for 10 d and were group-fed alfalfa pellets (4.7\% of BW). Camphene and caryophyllene oxide tended to decrease intake (linear contrasts were P = .0651 and P = .0504, respectively), while myrcene and beta-pinene had no effect on alfalfa pellet consumption during the 20-minute interval. Camphene and caryophyllene oxide may be involved in the differential herbivory of individual tarbush plants by livestock.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50861, title = {Effects of fire and mowing on expansion of reestablished black-tailed prairie dog colonies in Chihuahuan Desert grasslands}, booktitle = {2002 Fire Conference}, volume = {General Technical Report PSW-189}, year = {2002}, month = {December 2-5, 20}, pages = {49}, address = {San Diego, CA}, abstract = {Black-tailed prairie dogs (Cynomys ludovicianus) currently occupy less than 2\% of their historical range. This decline is due to eradication programs, habitat loss, and introduced pathogens. Active conservation measures for this species, including reintroduction, are underway in a number of areas. Prairie dogs are a key species in grassland ecosystems because of their effects on landscape pattern and ecosystem process. As part of a larger study of reciprocal effects of landscape and ecosystem factors on establishment and growth of prairie dog colonies, we investigated the effects of fire and mowing on numerical growth and aerial expansion of colonies reintroduced into the northern Chihuahuan Desert. On each of three colonies, established in 1998-1999 and ranging from 1.27 to 8 ha, we established six 50x50m experimental plots randomly assigned to burn or mowing treatments. The response variable was the number of new burrows appearing in each experimental plot. Results show no significant differences in the number of new burrows in burned vs. mowed plots; therefore, fire and mowing can be used interchangeably as management tools to reintroduce prairie dogs.}, author = {P. L. Ford and C.A. Anderson and E.L. Fredrickson and J. Truett and G. Roemer} } @unpublished {50866, title = {An extract from a 50th annimversary guidebook for the Desert Project (manuscript in preparation)}, year = {2002}, note = {//LOCAL,NMSU,JER//NONE//ProCite field[12]: In File (07/14/2004)}, month = {2002}, pages = {207 pp}, abstract = {This extract from the 50th anniversary guidebook for the Desert Project prepared for the Soil Science Institute held at the Desert Project in September 2002. The manuscript is in preparation with publication anticipated for 2006.}, keywords = {Desert Project, geomorphology, Desert Project, soil, flooding, playa, geomorphology, Desert Project, playa, flooding, playa, Isaacks Lake, soil, Desert Project}, author = {L. H. Gile and J. Hawley and R. Grossman and R. J. eds. Ahrens and Curtis H. Monger and F. F. Peterson and Gibbens, Robert P. and J.M. Lenz and Brandon T Bestelmeyer and B. Nolen} } @article {50867, title = {Elemental geochemistry of wind-erodible playa sediments, Owens Lake, California}, journal = {Nuclear Instruments and Methods in Physics Research B.}, volume = {189}, year = {2002}, note = {//NONE//LTER IV//}, month = {2002}, pages = {209-213}, abstract = {

Wind erosion of the dried bed (playa) of Owens Lake, California is an extremely intense source of mineral aerosol, transporting dust hundreds of kilometers downwind to critical ecological areas and several cities. A dust-producing site on the playa was studied over a four-year period to document the processes associated with aerosol emission. The playa takes on a variety of sedimentary forms and phases with surface crusts of differing susceptibilities to wind erosion. The sediments are classed into three general categories based on appearance: soft (saline), loose with drifting sand (salt{\textendash}silt{\textendash}clay), and hard and clean (silt{\textendash}clay). Sediment samples were collected over a two-year period as the study site cycled through all three crust types, and the samples were crushed and analyzed by PIXE. The results indicate that visual appearance and sedimentary structure does not correlate with elemental composition. All sediment types contain significant concentrations of various elements including sodium, calcium and silicon. Potentially toxic trace elements are also found in the sediments. All sediment types contain lead and/or arsenic in tens of parts per million, as well as various other heavy metals. Pb and As levels do not clearly correlate with salt content or sediment type. Arsenic levels may be slightly higher in the crusts with loose material present and potentially lower in the clean hard crusts, while Pb was least frequently detected in the samples with loose material. Future research will add mineralogical and stable isotope analyses to correlate with the PIXE data.

}, keywords = {Aerosols, PIXE, sediment}, doi = {10.1016/S0168-583X(01)01044-8}, url = {files/bibliography/JRN00355.pdf}, author = {Thomas E. Gill and D. E. Gillette and T. Niemeyer and Winn, R.} } @conference {50886, title = {Effects of leaf age on the photosynthetic capacity of sweetgum after 5 years CO2 enrichment}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {363}, address = {Tucson, AZ}, abstract = {We have been monitoring the effects of CO2 enrichment on photosynthetic capacity of sun and shade leaves of overstory sweetgum (Liquidambar styraciflua) trees for the past 5 years. Previously, (1997-1999), we found no effect of CO2 on photosynthetic capacity of sun or shade leaves. In this study, we examined whether CO2 enrichment affected photosynthetic capacity of sweetgum trees differentially in younger and older leaves. The Duke Forest FACe experiment consists of three control plots and three plots that have been fumigated with elevated CO2 (ambient plus 200 11-1) since August 1996. During June and September of 2000-2001, we measured A (net photosynthetic rate) versus Ci (calculated intercullular CO2) on sun and shade leaves, as well as the oldest sun leaves. Elevated CO2 stimulated net photosynthesis (A) in young shade and sun leaves and the oldest sun leaves (P <0.05). The maximum rate of carboxylation (Vcmax, from A-Ci curves) and electron transport (Jmax) were not significantly affected by CO2 enrichment for all leaf types examined during 2000 and 2001. Young sun leaves had approximately 30\% higher A, Vcmax and Jmax that the oldest sun leaves during September of 2000 and 2001 (P <0.05). Thus, we found no evidence of photosynthetic acclimation in sweetgum leaves after 5 years of treatment and, despite a decline in photosynthetic capacity with age, old sun leaves also did not acclimate to CO2 enrichment.}, author = {Jeffrey E. Herrick and Thomas, R.B.} } @article {50948, title = {Extending community ecology to landscapes}, journal = {Ecoscience}, volume = {9}, number = {2}, year = {2002}, month = {April 1, 2002}, pages = {200-212}, abstract = {A goal of landscape ecology is to infer processes or constraints that generate spatial pattern in communities and ecosystems. The rich tradition of plant community ecology is now being extended to address spatial pattern in vegetation over large spatial extents. The challenge is that vegetation pattern oil landscapes is fine-grained, which presents sampling problems for large study areas. Further, spatial autocorrelation in ecological data, coupled with strong patterns of correlation among environmental factors (such as the gradient complexes governed by elevation), makes it difficult to make clear inferences about the agents patterning landscape-scale vegetation. Here we review the methods of plant community ecology as extended to landscapes and illustrate the challenges with a case study from Sequoia-Kings Canyon National Park in California{\textquoteright}s southern Sierra Nevada. We outline an iterative approach to such studies with three stages. The first stage is a pilot study to characterize spatial scaling of environmental factors presumed to be important to vegetation; this stage can often be conducted virtually using digital terrain data. The second stage is iterative and consists of building a preliminary explanatory model using a combination of ordination, classification, and Mantel tests: all analyses based on the same ecological distance or dissimilarity matrices. This preliminary model is then attacked to find its uncertain or sensitive parts, and these parametric conditions are mapped into geographic space to identify candidate sites for follow up field studies in the third stage. This approach ensures the most uncertain aspects of the preliminary model are refined in an efficient manner. As the approach proceeds toward a richer understanding of species environment relationships and vegetation pattern, a need emerges for new kinds of field studies and novel extensions to existing statistical analyses. We discuss possible extensions of these as a natural consequence of this iterative process of model construction and revision.}, url = {http://www.unc.edu/~trl3/pubs/Urbanetal02.pdf}, author = {D.L. Urban and Sarah Goslee and Pierce, K. and Lookingbill, T.} } @article {50950, title = {The effect of temporal variations in rainfall on scale dependency in runoff coefficients}, journal = {Water Resources Research}, volume = {38}, number = {12}, year = {2002}, note = {//NMSU, USDA//LTER IV//Updated 12/11/2006}, month = {2002}, pages = {1271}, abstract = {

A series of numerical experiments was carried out to test the hypothesis that temporal variability of rainfall intensity during a storm can cause the commonly observed decrease in runoff coefficients with increasing slope length. The results demonstrate significant effects over even relatively short slope lengths. Sensitivity analyses show that the scale dependency of measured runoff coefficients is most sensitive to the infiltration parameters of the slope. Furthermore, it is also sensitive to the slope angle and the friction factor of the surface, because these parameters control the depth of overland flow. These results suggest that the combination of time-varying rainfall intensity during an event and run-on infiltration can provide an alternative to spatial variation in infiltration as an explanation for the scale-dependency of runoff coefficients that has been observed in the field. Overland-flow models which simply use the mean rainfall intensity are also shown to underpredict the runoff quite dramatically. The results imply that a better understanding of the temporal variability of rainfall intensities is important in both understanding field measurements and developing robust models of overland flow.

}, keywords = {article, articles, hydrology, overland-flow model, hydrology, run-on infiltration, hydrology, runoff coefficients, hydrology, scale dependency, hydrology, temporal variation, journal, journals, model, overland-flow}, doi = {10.1029/2000WR000188}, url = {files/bibliography/JRN00372.pdf}, author = {John Wainwright and A.J. Parsons} } @book {50953, title = {Ecology of Desert Systems}, year = {2002}, month = {March 1, 2002}, publisher = {Academic Press}, organization = {Academic Press}, address = {New York, NY}, abstract = {

Conventional wisdom considers deserts stark, harsh regions that support few living things. Most people also believe that water alone makes the desert bloom. Ecology of Desert Systems challenges these conventional views. This volume explores a broad range of topics of interest to ecosystem, population, community, and physiological ecologists. Climate, weather patterns, geomorphology, and wind and water processes are examined as variables that affect the distribution of biota through fundamental ecosystem processes. Descriptions of morphological, behavioral, and physiological adaptations of desert biota illuminate, through the lens of patch dynamics, principles for understanding observed patterns of primary production, nutrient cycling, and the effects of consumers. Desertification and the techniques for monitoring and quantifying it is examined within the framework of desert ecosystem patterns and processes. With 12 chapters and over 70 figures and tables, Ecology of Desert Systems is the only book that covers the entire desert ecosystem at this academic level. Readers are provided with an excellent reference framework for their desert ecology research.

}, keywords = {community, desert systems, ecology, physiological ecology, population, research}, url = {https://www.elsevier.com/books/ecology-of-desert-systems/whitford/978-0-12-815055-9}, author = {Walter G. Whitford}, editor = {Walter G. Whitford} } @article {50965, title = {Evaluation of the internal colonization of Atriplex canescens (Pursh) Nutt. roots by dark septate fungi and the influence of host physiological activity}, journal = {Mycorrhiza}, volume = {11}, number = {4}, year = {2001}, month = {May 12, 2001}, pages = {199-205}, chapter = {199}, abstract = {

Dark septate (DS) fungal endophytes are the primary root colonizers of fourwing saltbush, Atriplex canescens (Pursh) Nutt, a dominant and ecologically important shrub in southwestern USA rangelands. These fungi are characteristically identified as stained or pigmented hyphae and microsclerotia in the root cortex using conventional fungus staining methods. A. canescens roots colonized by DS fungi were stained with sudan IV and analyzed with differential interference microscopy (DIC). This method revealed substantial internal colonization of the cortex and vascular cylinder by vacuolated hyaline hyphae that were not evident when stained with trypan blue. Hyaline hyphae were internal extensions of melanized DS hyphae and microsclerotia. Sudan IV intensely stained lipids in fungal vacuoles, further enhancing visibility of internal hyaline hyphae. Melanized hyphae and microsclerotia were more abundant in roots sampled from dormant and relatively inactive plants while hyaline hyphae and lipid accumulation were most prevalent in roots of physiologically active plants. The polymorphic nature of DS fungal endophytes, their dynamic response to metabolic activity, and their similarities and differences relative to aseptate fungal colonization in A. canescens roots are discussed.

}, keywords = {Atriplex canescens, dark septate, evaluation, fourwing saltbush, fungal endophytes, internal colonization}, doi = {10.1007/s005720100111}, url = {/files/bibliography/01-008.pdf}, author = {J.R. Barrow and Aaltonen, R.E.} } @inbook {50975, title = {Exploiting heterogeneity of soil organic matter in rangelands: Benefits for carbon sequestration}, booktitle = {The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect}, year = {2001}, month = {August 1, 2001}, pages = {121-136}, publisher = {Ann Arbor Press}, organization = {Ann Arbor Press}, chapter = {5}, address = {Chelsea, MI}, abstract = {

Rangelands pose unique challenges to the goal of increasing soil carbon sequestration. The high level of spatial variability associated with soil organic matter, soil aggregation, soil water, and other resources in rangelands presents unique opportunities for management. In this chapter, we review spatial heterogeneity of carbon sequestration at aggregate, plant, community, and landscape scales. We propose that Tisdall and Oades\&$\#$39; soil aggregation hierarchy model be extended to the landscape scale, and show that this model can be applied to optimize carbon sequestration and/or rangeland function through targeted management inputs. This approach explicitly recognizes that the capacity of rangeland ecosystems to sequester carbon is a function of interactions between the spatial distribution of plant production and of soil and water resources. Management inputs can be targeted to parts of the landscape which already have a high potential for enhanced productivity and carbon storage due to higher resource availability. Although this approach can be implemented immediately, its success could be significantly enhanced by a more holistic understanding of rangeland systems and the relationships between soil structure, soil organic matter, and nutrient and water distribution at a variety of spatial scales.

}, url = {/files/bibliography/01-016.pdf}, author = {S.B. Bird and Jeffrey E. Herrick and Wander, M.M.} } @article {50980, title = {Estimating PM10 concentrations from dust storms in Iraq, Kuwait, and Saudi Arabia}, journal = {Atmospheric Environment}, volume = {35}, number = {25}, year = {2001}, note = {//NONE//LTER IV//}, month = {2001}, pages = {4315-4330}, abstract = {

A model for the emission of PM10 dust has been constructed using the concept of a threshold friction velocity which is dependent on surface roughness. Surface roughness in turn was correlated with geomorphology or soil properties for Kuwait, Iraq, part of Syria, Saudi Arabia, the United Arab Emirates and Oman. The PM10 emission algorithm was incorporated into a Lagrangian transport and dispersion model. PM10 air concentrations were computed from August 1990 through August 1991. The model predicted about the right number of dust events over Kuwait (events occur 18\% of the time). The model results agreed quantitatively with measurements at four locations in Saudi Arabia and one in Kuwait for one major dust event (\> 1000 mug/m(3)). However, for smaller scale dust events (200-1000 mug/m(3)), especially at the coastal sampling locations, the model substantially over-predicted the air concentrations. Part of the over-prediction was attributed to the entrainment of dust-free air by the sea breeze, a flow feature not represented by the large-scale gridded meteorological data fields used in the model computation. Another part of the over-prediction was the model{\textquoteright}s strong sensitivity to threshold friction velocity and the surface soil texture coefficient (the soil emission factor), and the difficulty in accurately representing these parameters in the model. A comparison of the model predicted PM to spatial pattern with the TOMS satellite aerosol index (Al) yielded a spatial pattern covering a major portion of Saudi Arabia that was quite similar to the observed Al pattern. Published by Elsevier Science Ltd.

}, keywords = {aeolian processes, dust emissions, model, dust emission, model, PM10 dust, aeolian processes, PM10 dust}, doi = {10.1016/S1352-2310(01)00159-5}, url = {files/bibliography/JRN00329.pdf}, author = {Draxler, R. and D. E. Gillette and Kirkpatrick, J. and Heller, J.} } @conference {50981, title = {Effects of fire and grazing on vegetation in northern Chihuahuan Desert grasslands}, booktitle = {86th Annual Meeting, Ecological Society of America}, year = {2001}, month = {August 6-10, 200}, pages = {273}, address = {Madison, WI}, abstract = {We examined experimentally the effects of growing season fires and livestock grazing on plant community structure in Chihuahuan desert grasslands of southern New Mexico. Four 200m x 200m plots were established in each of four different blocks. Treatments were either applied or not applied, resulting in four treatment combinations that were each assigned randomly to one of the four plots within each block. Fires were prescribe in June 1999. Beginning in September 1999, unfenced plots were exposed to 12 months of continuous livestock grazing where utilization was <40\%. Plant cover and frequency were measured immediately before and after treatments using a vertical line point intercept method every 10cm along five 150m-transects within each plot. Cover of Bouteloua eriopoda, the dominant perennial grass, decreased only by 1.22\% following burning but increased 2.20\% in fire-excluded areas. Its frequency decreased 6.49\% and 0.48\% in burned and unburned plots, respectively. After fires, collective perennial forb cover and frequency increased 1.46\% and 3.81\%, respectively, but decreased as much as 4.04\% in unburned plots. Cover and frequency of annuals also increased up to 7.25\% and 20.63\% respectively in burned plots but increased as little as 0.3\% in fire-excluded areas. Livestock grazing had a similar effect as fire on only cover of B. eriopoda. Contrary to past research, fire did not result in delayed recovery of B. eriopoda. Additionally, greater increases in cover and frequency of perennial forbs and annuals after burning enhanced overall grassland diversity. Rapid vegetation responses following fire may have been influenced by patterns of precipitation that were equivalent to the average, especially in the immediate post-fire environment.}, author = {Drewa, P.B. and Debra C. Peters and Kris Havstad} } @article {50983, title = {Effects of fire, grazing, and the presence of shrubs on Chihuahuan desert grasslands}, journal = {Journal of Arid Environments}, volume = {48}, number = {4}, year = {2001}, month = {August 1, 2001}, pages = {429-443}, abstract = {

Responses of herbaceous and suffrutescent species to fire, grazing, and presence of Prosopis glandulosa were examined in a Chihuahuan Desert grassland in south central New Mexico. Treatments were assigned randomly to eight, 12m x 8m plots within each of two blocks. Following fires in June 1995, unfenced plots were exposed to livestock grazing over four years. Plots were established that either included or excluded P. glandulosa. Species cover and frequency were estimated before and after treatments. Perennial grass cover, primarily Bouteloua eriopoda, decreased 13\% in burned plots but increased 5\% in unburned areas. Conversely, perennial forb cover was 4\% greater after fire. Frequency of perennial grasses and forbs decreased 30\% more and increased 10\% more respectively in burned than unburned areas. Further, species diversity increased 225\% more following burning and was attributed to increases in evenness. In general, ,grazing had similar effects as fire, and the presence of P. glandulosa had no effect on responses of non-shrub species. Fires were conducted during near drought conditions while grazing occurred during years of precipitation equivalent to the long-term average. Precipitation immediately following fire may be critical for recovery of B. eriopoda dominated desert grasslands; relationships between fire and post-fire precipitation patterns require future investigation.

}, doi = {10.1006/jare.2000.0769}, url = {files/bibliography/JRN00328.pdf}, author = {Drewa, P.B. and Kris Havstad} } @article {50985, title = {Extracts of Flourensia cernua reduce consumption of alfalfa pellets by sheep}, journal = {Journal of Chemical Ecology}, volume = {27}, number = {11}, year = {2001}, month = {November 1, 2001}, pages = {2275-2285}, abstract = {

Effects of three extracts (hexanes, ether and ethanol) from tarbush on intake of alfalfa pellets by lambs were examined in 2 experiments. Forty-five ewe lambs were fed 1 of 5 treatments for 5 days. Treatments were alfalfa pellets (CON) or alfalfa pellets plus ethanol carrier (CAR), hexanes extract (HEX), ether extract (ETH), or ethanol extract (ETOH). Extracts were applied to alfalfa pellets at the same concentration as in an equivalent amount of tarbush in experiment 1 and at 10-fold dilutions of that concentration in experiment 2. Treatments were isolated from 36 kg of tarbush leaves using a sequential extraction with hexanes, diethyl ether and 100\% ethanol. Extracts were obtained in batches (3 kg of leaves in 7 liters of solvent) with constant mixing (22 hr per solvent), filtered, solvents removed using a rotary evaporator and residue resuspended in ethanol. Lambs received 640 g of alfalfa pellets each morning and intake was monitored during a 20-min interval. In experiment 1, mean intake by lambs during the 20-min interval was 361, 393, 204, 212 and 228 g for CON, CAR, HEX, ETH and ETOH, respectively (SEM = 28.9). All 3 extracts decreased intake (P \< .0001) compared to CON or CAR. Intake did not differ among the 3 extracts (HEX, ETH and ETOH) nor between the 2 controls (CON and CAR). Mean intake did not differ among treatments in experiment 2 (468, 455, 389, 381 and 431 g for CON, CAR, HEX, ETH and ETOH, respectively; SEM = 30.5; P = .187). Because all 3 extracts decreased intake of alfalfa pellets at concentrations normally encountered in intact plants, several compounds are probably responsible for the low palatability and differential use of tarbush typically exhibited by livestock.

}, keywords = {alfalfa pellets, consumption, fluorensia cernua extracts, sheep}, doi = {10.1023/A:1012235121852}, url = {/files/bibliography/01-021.pdf}, author = {Richard E. Estell and M.R. Tellez and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {51032, title = {Evaluation of water, energy, and ecosystems in southern New Mexico}, booktitle = {American Water Resources Association Annual Conference }, year = {2001}, month = {November 11, 200}, pages = {51}, address = {Albuquerque, NM}, abstract = {Large area, repetitive observations of surface characteristics in the Chihuahuan Desert, using multilevel remote sensing data, have been conducted at the Jornada Experimental Range (JER) near Las Cruces, New Mexico, since 1995. The Jornada Experiment (JORNEX) measurement campaigns are conducted twice a year, before and after the summer monsoon season. The basic data obtained during each campaign include ground-based hyperspectral and thermal observations in association with leaf-area index and line-intercept transect vegetation measurements. At the time of the ground observations, multispectral radiometer, multispectral video, and thermal infrared data are taken by low altitude aircraft flights. All measurements are coordinated with Landsat and Terra satellite passes. In addition to the basic data, various observations are made at selected times and include airborne bidirectional reflectance and hyperspectral (AVIRIS) data, airborne MASTER data and ground-based eddy correlation data. The JE (783 km2), bordering the Rio Grande about 37 km north of Las Cruces, has proven to be a fruitful experimental area because of several ongoing programs, including the Jornada Long Term Ecological Research (LTER) project, designation as a NASA Earth Observation System (EOS) Core Site, and the fact ground measurements have been conducted at Jornada since 1912, thereby documenting long-term ecological change.}, author = {A. Rango and M. Chopping and Kris Havstad and Kris Havstad and Jerry Ritchie and William P. Kustas and T. J. Schmugge} } @proceedings {51042, title = {Estimation of surface emissivity for arid lands}, year = {2001}, note = {//?//LTER IV//Updated per Al Rango 01/04/2006}, month = {2001}, address = {Santa Fe, NM}, keywords = {abstract, abstracts, arid lands, conference, conference proceedings, conferences, emissivity, proceeding, proceedings}, author = {T. J. Schmugge and A.N. French and Jerry Ritchie and A. Rango} } @article {51050, title = {Extracts of Fluorensia cernua (L): volatile constituents and antifungal, antialgal, and antitermite bioactivities}, journal = {Journal of Chemical Ecology}, volume = {27}, number = {11}, year = {2001}, month = {November 1, 2001}, pages = {2263-2273}, abstract = {The chemical components of 36 kg of tarbush (Flourensia cernua) leaves were fractionated by extracting successively with hexanes, diethyl ether, and ethanol. Volatile profiles of each fraction were identified using GCMS. The hexanes fraction was found to contain mostly monoterpenoids while the ethanol fraction volatiles were primarily sesquiterpenoids. The crude fractions were tested for activity against fungi, algae, and termites. Application of as little as 1 \æg of the essential oil obtained from the hexanes fraction was sufficient to provide visible antifungal activity in bioautography assays. The diethyl ether fraction showed selective activity against the cyanobacterium responsible for 2-methylisoborneol induced off- flavor sometimes associated with catfish farming operations. All three fractions exhibited a high degree of antitermite activity.}, url = {/files/bibliography/01-049.pdf}, author = {M.R. Tellez and Richard E. Estell and E.L. Fredrickson and Powell, J.E. and Wedge, D.E. and Schrader, K. and Kobaisy, M.M.} } @article {51061, title = {Establishment and effects of establishment of creosotebush, Larrea tridentata, on a Chihuahuan Desert watershed}, journal = {Journal of Arid Environments}, volume = {47}, number = {1}, year = {2001}, month = {January 1, 2001}, pages = {1-10}, abstract = {Creosotebush (Larrea tridentata) seedlings were planted in plots that were irrigated, plots that were irrigated and fertilized with ammonium nitrate, and plots that were not amended in three plant communities on a Chihuahuan Desert watershed: ungrazed black grama (Bouteloua eriopoda) grassland, creosotebush shrubland, and overgrazed grassland. No seedlings were planted in one-half of the area of each plot. No seedlings survived in the black grama grassland or the creosotebush shrubland 2 years after planting. Growth of established creosotebush shrubs was highest in plots with the lowest grass cover. Fifteen years after the seedlings were planted in the overgrazed grassland, the area under the shrubs was nearly devoid of perennial grasses and forbs. The aggregate stability of the soils under the established creosotebush shrubs was significantly lower than the soils in the unplanted split-half of the plots. Electrical conductivity, calcium, and nitrate were significantly lower in soils under shrubs than soils in the unplanted split-half of the plots. There were also significant reductions in densities of annual plants growing under the shrubs than in the unplanted split-half of the plots. Successful establishment of creosotebush in desert grasslands is dependent upon the presence of large patches of soil with no perennial plant cover. Intense grazing by domestic livestock creates microsites and landscape characteristics favorable for seed dispersal, germination and establishment of creosotebush. Soil changes resulting from shrub establishment reduce the probability of reestablishing perennial grasses in creosotebush-dominated shrubland.}, keywords = {Chihuahuan Desert, creosotebush, effects, establishment, Larrea tridentata}, url = {/files/bibliography/01-057.pdf}, author = {Walter G. Whitford and R. M. Nielson and A.G. de Soyza} } @article {51068, title = {Effect of individual terpenes on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {78}, number = {6}, year = {2000}, month = {June 1, 2000}, pages = {1636-1640}, abstract = {

We examined effects of five individual terpenes on alfalfa pellet intake of lambs. In each experiment, 45 lambs were individually fed alfalfa pellets sprayed with either p-cymene, alpha-humulene, 1,8-cineole, 3-carene, or sabinene at one of five concentrations. Treatment levels (0, .5, 1, 2, and 10X) were multiples of the concentrations (X) of specific terpenes in tarbush that were related to differential herbivory by livestock in previous studies. Treatments were applied to alfalfa pellets (.64 kg/lamb/d, DM basis), and consumption during a 20-min interval was measured for 5 d. Lambs were adapted to handling and pen feeding for 10 d, and were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 4.7\% of BW (DM basis). None of the five compounds examined decreased pellet consumption during the 20-min interval. These five mono- and sesquiterpenes do not appear to be responsible for differential herbivory of individual tarbush plants by livestock.

}, keywords = {alfalfa pellets, herbivory, individual terpenes, lambs, sheep}, url = {/files/bibliography/00-008.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {51071, title = {The effect of feeding ewe lambs a 15\% tarbush (Flourensia cernua DC) pellet pre- and post-weaning on the subsequent diet selection of tarbush}, journal = {Journal of Arid Environments}, volume = {44}, number = {1}, year = {2000}, month = {January 1, 2000}, pages = {123-131}, abstract = {

The shrub Flourensia cernua (tarbush) has rapidly increased in dominance within Chihuahuan Desert grasslands, and is comparable to alfalfa in nutrient density. Increasing tarbush in livestock diets may improve diet quality, while decreasing tarbush dominance. We determined dietary preference for tarbush by sheep and the effect of previous exposure on preference. Thirty-eight ewe lambs received either tarbush or alfalfa in sorghum-based pellet 120 days postparturition; after which, dietary preference was assessed. Previous exposure averted lambs from tarbush consumption. Lambs without previous exposure maintained greater intakes initially, but declined with time. This decline corresponds with onset of tarbush toxicosis.

}, keywords = {ewe lambs, Flourensia cernua, post-weaning, pre-weaning, tarbush}, doi = {10.1006/jare.1999.0571}, url = {/files/bibliography/00-003.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @article {51077, title = {Environmental controls on nitric oxide emission from northern Chihuahuan desert soils}, journal = {Biogeochemistry}, volume = {50}, year = {2000}, note = {//NMSU, USDA//LTER III//}, month = {2000}, pages = {279-300}, abstract = {

A survey of nitric oxide (NO) emission from Chihuahuan desert soils found mean NO fluxes \<0.1 ng NO-N cm-2 h-1 during the dry season. These fluxes were at the lower end of the range reported for temperate grassland and woodland ecosystems. NO fluxes from wet or watered soils were higher (0.1-35 ng NO-N cm-2 h-1). Watering of black grama grassland soils produced an initial pulse of 12 ng cm-2 h-1 (12-h after 1-cm watering) with high fluxes sustained over 4 days with repeated watering. Initial pulses from shrubland soils were lower (maximum 5 ng cm-2 h-1), and fluxes declined with repeated watering. Repeated watering of creosotebush soils depleted the soil NH4+ pool, and NO emissions were directly related to soil NH4+ concentrations at the end of the experiment. In watered and NH4+-fertilized creosotebush soils, NO fluxes were positively related to potential net nitrification rates. NH4+-fertilization boosted the initial NO pulse 15 times in the shrubland and 5 times in black grama grassland relative to watered controls. These experimental results point toward greater substrate limitation in shrublands. In this desert basin, NO emission averaged 0.12 kg N ha-1 y-1 in untreated soil and 0.76 kg N ha-1 y-1 in watered soil. We multiplied these averages by the distribution of grassland and shrubland vegetation within a 58,600-ha area of the Jornada del Muerto basin to estimate regional losses of 0.150.38 kg NO-N ha -1 y-1 for this area of the Chihuahuan desert.

}, keywords = {article, articles, biogeochemistry, grassland, trace gas loss, journal, journals, model, nitrogen trace gas loss, nitric oxide, shrubland, trace gas loss, soil nitrogen losses, trace gas losses, nitrogen}, doi = {10.1023/A:1006377832207}, url = {files/bibliography/JRN00300.pdf}, author = {Anne E. Hartley and W. H. Schlesinger} } @conference {51084, title = {Effects of shrubs and disturbances on pattern and process in Chihuahuan Desert grasslands}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6, 2000}, pages = {393}, address = {Snowbird, UT}, abstract = {

Disturbances can cause patchiness in the vegetation at different spatial and temporal scales. In arid environments, dominant species of the vegetation are similar to disturbances in that they create patches with a modified biotic and abiotic environment. Shrub invasion in arid environments has caused a shift in the dominant life form, which is expected to have important implications for the occurrence of subdominant plants. The objective of this study was to understand and predict changes in the relative abundance of subdominant species when an evergreen shrub (Larrea tridentata) invades desert grasslands dominated by Bouteloua eriopoda, and to compare those changes to other disturbances that affect the vegetation. We used a spatially-explicit individual-plant based model (ECOTONE) to simulate responses of desert grassland species to shrub invasion using a hierarchical patch dynamics approach. The effects of changes in light, water, and nutrients caused either by disturbance or shrub invasion on subdominant species were evaluated. We found that the effects of shrub invasion on species composition were comparable to other disturbances. However, contrary to other disturbances, changes in processes induced by shrub invasion appear to be self-reinforcing, whereas species recover after disturbances. As a consequence, initially positive effects of shading by shrubs on the abundance of subdominant species ultimately caused a loss of subdominant plants as shrub cover increased. These results correspond to field data collected at a desert grassland-shrubland ecotone at the Sevilleta LTER in New Mexico. Our study demonstrates the similarity and differences of invasive species to disturbances.

}, keywords = {Chihuahuan Desert, disturbances, grasslands, Sevilleta LTER, shrub invasion}, author = {Hochstrasser, T. and Debra C. Peters} } @conference {51086, title = {Effects of plant removals on soil surface erosion in a Chihuahuan Desert shrubland}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {290}, address = {Snowbird, UT}, abstract = {Humans are dramatically altering the patterns of biological diversity in semiarid ecosystems worldwide, in particular by altering the relative abundance of different growth forms (shrubs vs. perennial grasses) and by reducing the numbers of species within growth forms. We are exploring the impact of reduced plant diversity in experimental plots of creosotebush (Larrea tridentata) shrubland at the Jornada Basin LTER site near Las Cruces, NM, USA. In 1995, eight treatments of varying severity of plant community alteration were imposed on 25m x 25m plots (six replicates of each treatment); treatments ranged from no removals to extreme simplification of the perennial community (one shrub species, one grass species, one succulent, etc.). These treatments have been maintained since 1995. We have monitored soil erosion and sediment movement within these plots since spring 1996 by collecting sediment in pans at the downslope edge of each plot. Fine materials (particle diameter <2mm) dominate total soil movement (by weight), although larger particles are transported in this system, especially during the summer-fall season of intense episodic rainfall. Fine particle movement is higher in shrub removal and grass removal treatments than in controls during some seasons, especially in the summer. No statistically significant differences were detected during other seasons. Location on the slope with respect to local channels or arroyos contributes significantly to variation in the amount of material moving within a plot, as does the nature of vegetative cover and soil surface characteristics in the immediate vicinity of a collecting pan. Our results suggest the relationship between plant community structure and soil erosion rates is best examined at the scale of local patches.}, keywords = {Chihuahuan Desert, plant removal, shrubland, soil erosion}, author = {L. Huenneke and M. Buonopane and Bothern, L. and Jeffrey E. Herrick} } @conference {51089, title = {Effects of small patchy distrubances on plant species diversity at a semiarid grassland ecotone}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {393}, address = {Snowbird, UT}, abstract = {Our objective was to evaluate the effects of patchy disturbances created by kangaroo rats on species diversity and composition at a semiarid-arid grassland ecotone. Our study was conducted at the Sevilleta LTER in New Mexico, where a grassland dominated by Bouteloua gracilis, a shortgrass steppe species, and a grassland dominated by B. eriopoda, a Chihuahuan Desert species, meet to form patches across the landscape. Four 0.4 ha plots were sampled for vegetation within a 7m x 7m grid in each grassland type. Kangaroo rat mounds were also mapped and sampled in 4 areas of 1.6 ha in each grassland type. The landscape scale abundance of many subordinate species was increased significantly by populations occurring on kangaroo rat mounds in both grassland types. Dominant plants on mounds in the B. eriopoda type were also abundant in off-mound areas whereas dominant plants on mounds in the B. gracilis type were not as abundant off-mound. These results indicate that the presence of mounds in B. gracilis dominated grasslands creates islands of plant communities that are distinct from the rest of the grassland. Therefore, the occurrence of certain plant species in this grassland may be intimately associated with the disturbance regime at this ecotone.}, keywords = {grassland, kangaroo rats, patchy disturbances, semiarid-arid, species diversity}, author = {G. Kroel-Dulay and Hochstrasser, T. and Debra C. Peters} } @article {51107, title = {The EOS prototype validation exercise (PROVE) at Jornada: Overview and lessons learned}, journal = {Remote Sensing of Environment}, volume = {74}, number = {1}, year = {2000}, note = {Entered in ARIS at Beltsville February 15, 2000}, month = {October 1, 2000}, pages = {1-12}, abstract = {

The Earth Observing System (EOS) instrument teams must validate the operational products they produce from the Terra spacecraft data. As a pilot for future validation activities, four EOS teams (MODIS, MISR, ASTER, and Landsat-7) and community experts conducted an 11-day field campaign in May 1997 near Las Cruces, NM. The goals of the Prototype Validation Exercise (PROVE) included (1) gaining experience in the collection and use of field data for EOS product validation; (2) developing coordination, measurement, and data-archiving protocols; and (3) compiling a synoptic land and atmospheric data set for testing algorithms. PROVE was held at the USDA-Agricultural Research Service{\textquoteright}s (ARS) Jornada Experimental Range, an expansive desert plateau hosting a complex mosaic of grasses and shrubs. Most macroscopic variables affecting the radiation environment were measured with ground, air-borne (including AVIRIS and laser altimeter), and space-borne sensors (including AVHRR, Landsat TM, SPOT, POLDER, and GOES). The Oak Ridge Distributed Active Archive Center (DAAC) then used campaign data sets to prototype Mercury, its Internet-based data harvesting and distribution system. This article provides general information about PROVE and assesses the progress made toward the campaign goals. Primary successes included the rapid campaign formulation and execution, measurement protocol development, and the significant collection, reduction, and sharing of data among participants. However, the PROVE data were used primarily for arid-land research and model validation rather than for validating satellite products, and the data were slow to reach the DAAC and hence public domain. The lessons learned included: (1) validation campaigns can be rapidly organized and implemented if there are focused objectives and on-site facilities and expertise; (2) data needs, organization, storage, and access issues must be addressed at the onset of campaign planning; and (3) the end-to-end data collection, release, and publication environment may need to be readdressed by program managers , funding agencies, and journal editors if rapid and comprehensive validation of operational satellite products is to occur.

}, keywords = {ASTER, Earth Observing System, EOS, MODIS, Prototype Validation Exercise, PROVE}, doi = {10.1016/S0034-4257(00)00117-6}, url = {/files/bibliography/00-018.pdf}, author = {Privette, J.L. and G.P. Asner and Conel, J. and Huemmrich, K.F. and R. Olson and A. Rango and Rahman, A.F. and Thome, K. and Walter-Shea, E.A.} } @article {51110, title = {Effects of long-term rainfall variability on evapotranspiration and soil water distribution in the Chihuahuan Desert: A modeling analysis}, journal = {Plant Ecology}, volume = {150}, year = {2000}, note = {//NMSU//LTER III//}, month = {2000}, pages = {145-159}, abstract = {

We used the patch arid land simulator (PALS-FT) -- a simple, mechanistic ecosystem model -- to explore long-term variation in evapotranspiration (ET) as a function of variability in rainfall and plant functional type (FT) at a warm desert site in southern New Mexico. PALS-FT predicts soil evaporation and plant transpiration of a canopy composed of five principal plant FTs: annuals, perennial forbs, C4 grasses, sub-shrubs, and evergreen shrubs. For each FT, the fractional contribution to transpiration depends upon phenological activity and cover as well as daily leaf stomatal conductance, which is a function of plant water potential, calculated from root-weighted soil water potential in six soil layers. Simulations of wat6er loss from two plant community types (grass- vs. shrub-dominated) were carried out for the Jornada Basin, New Mexico, using 100 years of daily precipitation data (1891-1990). In order to emphasize variability associated with rainfall and fundamental differences in FT composition between communities, the seasonal patterns cover of perennials were held constant from year to year. Because the relative amount of year to year cover of winter and summer annual species is highly variable in this ecosystem, we examined their influence on model predictions of ET by allowing their cover to be variable, fixed, or absent. Over the entire 100-yr period, total annual ET is highly correlated with total annual rainfall in both community types, although T and E alone are less strongly correlated with rainfall, and variation in transpiration is nearly 3 times greater than evaporation and 2 times greater than variation in rainfall (CV of rainfall = 35\%). Water use shows a relatively high similarity between the grass- and shrub-dominated communities, with a 100-yr average T/ET of 34\% for both communities. However, based on a year-by-year comparison between communities, T/ET was significantly greater in the grass-dominated community, reflecting the fact that over the long term more than half of the rain occurs in the summer and is used slightly more efficiently (T\>E) by the C4-grass community than the shrub community, although we found some rainfall patterns that resulted in much greater T/ET in the shrub community in a given year. Percent of water lost as transpiration (T/ET) suggests that while there is a general trend toward increased T/ET with rainfall in both community types, T/ET is extremely variable over the 100-yr simulation, especially for normal and below normal amounts of rainfall (T/ET values range from 1 to 58\% for the grass-dominated site and 6 to 60\% for the shrub-dominated site). These predictions suggest that because of the relatively shallow distribution of soil water, there is little opportunity for vertical partitioning of the soil water resource by differential rooting depths of the plant FTs. However, functional types may avoid competition by keying on particular "windows" of moisture availability via differences in phenologies. We found very little differences in average, long-term model predictions of T, E, and ET when annual plant cover was variable, fixed, or absent. The results of our simulations help reconcile some of the disparate conclusions drawn from experimental studies about the relative contribution of transpiration vs. evaporation to total evapotranspiration, primarily by revealing the great year-to-year variability that is possible.

}, keywords = {article, articles, Bouteloua, evapotranspiration, desertification, model, evapotranspiration, Boutelous eriopoda, evapotranspiration, rainfall, evapotranspiration,grassland, evapotranspiration,model, grass, evapotranspiration, journal, journals, Larrea, evapotranspiration, model,, model, PALS, model, rainfall variability, model, soil water distribution, rainfall, evaporation, rainfall, soil water, shrubs, evapotranspiration, soil water, evapotranspiration, soil water, rainfall}, doi = {10.1023/A:1026530522612}, url = {files/bibliography/JRN00299.pdf}, author = {J. F. Reynolds and P. R. Kemp and Tenhunen, J. D.} } @proceedings {51117, title = {Estimation of surface emissivity for arid lands}, volume = {IAHS Publication No. 267}, year = {2000}, month = {2001}, pages = {168-174}, publisher = {Remote Sensing and Hydrology}, address = {Santa Fe, NM}, abstract = {

Knowledge of surface emissivity is important for determining the radiation balance at the land surface. For heavily vegetated surfaces there is little problem since the emissivity is relatively uniform and close to one. For arid lands with sparse vegetation the problem is more difficult because the emissivity of the exposed soils and rocks is highly variable. With multispectral thermal infrared (TIR) observations it is possible to estimate the spectral emissivity variation for these surfaces. The data presented is from the TIMS (Thermal Infrared Multispectral Scanner) instrument which has six channels in the 8 to 12 {\textmu}m region. TIMS is a prototype of the TIR portion of the ASTER (Advanced Spaceborne Thermal Emission and Reflection radiometer) instrument on NASA{\textquoteright}s EOS-TERRA satellite. The approach is to use the Temperature Emissivity Separation (TES) algorithm developed for use with ASTER data to extract the temperature and six emissivities from the six channels of TIMS data. The algorithm makes use of the empirical relation between the range of observed emissivities and their minimum value. This approach was applied to the TIMS data acquired over the USDN ARS Jornada Experimental Range in New Mexico. The Jornada site is typical of a desert grassland where the main vegetation components are grass (black grama) and shrubs (primarily mesquite) in the degraded grassland. The data are from an altitude of 800 m yielding a pixel resolution of approximately 2 m. The result-ing spectral emissivities are in qualitative agreement with laboratory measurements of the emissivity (E) for the quartz rich soils of the site with{\textsterling}\< 0.8 for the 8-9.5 {\textmu}m channels. For the longest wavelength channel little spatial variation of{\textsterling} was observed with values of0.96 {\textpm} 0.005 over large areas.

}, keywords = {arid lands, ASTER, Chihuahuan Desert, emissivity, Jornada, multispectral, surface temperature, Thermal infrared, TIMS}, url = {/files/bibliography/01-081.pdf}, author = {T. J. Schmugge and A.N. French and Jerry Ritchie and A. Rango} } @conference {51139, title = {Effects of terpenes on intake of alfalfa pellets by sheep}, booktitle = {91st National Meeting of the American Society of Animal Science}, volume = {77(1)}, year = {1999}, month = {July 21-23, 1999}, pages = {207}, address = {Indianapolis, IN}, abstract = {Five experiments were conducted to examine influences of terpenes on intake of alfalfa pellets by sheep. Five mono- and sesquiterpenes that were related to tarbush (Flourensia cernua) consumption by livestock in previous studies using multivariate analysis were examined individually. Average concentrations of selected compounds (C) were 5, 25, 50, 100, and 10 micro g/g of tarbush DM for para-cymene, alpha-humulene, 1,8-cineole, 3-carene, and sabinene, respectively. During each experiment, 45 individually penned lambs received one of five treatments (multiples of C: 0X, .5X, 1X, 2X, or 10X) for five consecutive days. Treatments were applied to alfalfa pellets (.64 kg, DM basis) and intake was monitored during a 20 min interval each morning. Lambs were adapted to handling and individual pen feeding for 10 d before experiments began and were maintained and fed alfalfa pellets (4.7\% of BW, DM basis) as one group except during 20 min tests. No linear or quadratic responses of intake to treatment level were detected (P > .05 for any of the five compounds. These five terpenes had little influence on consumption of alfalfa pellets, suggesting these compounds are not responsible for differential herbivory of individual tarbush plants by livestock.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {51160, title = {Effects of aqueous leaf extracts of creosotebush, larrea tridentata, on germination of seven species of sympatric plants}, booktitle = {5th Symposium on Resources of the Chihuahuan Desert Region: US and Mexico}, year = {1999}, month = {October 7-8, 199}, pages = {Abstract 24}, address = {Alpine, TX}, abstract = {We exposed seven species of plant seeds to aqueous extracts of Creosotebush leaves: Black Grama, Bouteloua eriopoda; Sideoats Grama, B. curtipendula; Burrograss, Scleropogon brevifolous; Fluffgrass, Dasyochloa pulchella; Bush Muhly, Muhlenbergia porteri; Tarbush, Fluorensia cernua; and, Creosotebush, Larrea tridentata. We also included lettuce as a standard bioassay for allelopathic effects. Extract concentrations varied from 0 to 50 times th concentration found in stemflow during a typical summer rainfall event. Germination and radicle elongation of plant species closely associated with Creosotebush were affected differently than those whose populations are reduced with increasing Creosotebush density.}, author = {Hu, D. and E.L. Fredrickson and P.W. Hyder and Richard E. Estell} } @article {JRN55154, title = {Evaluating Change in Rangeland Condition using Multitemporal AVHRR Data and Geographic Information System Analysis}, journal = {Environmental Monitoring and Assessment}, volume = {59}, year = {1999}, month = {November 1999}, pages = {211{\textendash}223}, abstract = {

Coarse-scale, multitemporal satellite image data were evaluated as a tool for detecting variation in vegetation productivity, as a potential indicator of change in rangeland condition in the western U.S. The conterminous U.S. Advanced Very High Resolution Radiometer (AVHRR) biweekly composite data set was employed using the six-year time series 1989{\textendash}1994. Normalized Difference Vegetation Index (NDVI) image bands for the state of New Mexico were imported into a Geographic Information System (GIS) for analysis with other spatial data sets. Averaged NDVI was calculated for each year, and a series of regression analyses were performed using one year as the baseline. Residuals from the regression line indicated 14 significant areas of NDVI change: two with lower NDVI, and 11 with higher NDVI. Rangeland management changes, cross-country military training activities, and increases in irrigated cropland were among the identified causes of change.

}, keywords = {analysis, GIS, multitemporal, NDVI, Rangeland condition, remote sensing}, doi = {10.1023/A:1006126622200}, url = {files/bibliography/99-EnvironlMonitoring\&Assessment-Whtiford.pdf}, author = {T. Minor and J. Lancaster and T. Wade and James D. Wickham and James D. Wickham} } @article {51199, title = {Effects of habitat characteristics on the abundance and activity of subterranean termites in arid southeastern New Mexico (Isoptera)}, journal = {Sociobiology}, volume = {34}, number = {3}, year = {1999}, month = {December 1, 1999}, pages = {493-504}, abstract = {

Amitermes wheeleri was the most abundant termite species in most of the habitats. Gnathamitermes tubiformans was the most abundant subterranean termite species in habitats dominated by creosotebush, Larrea tridentata. Subterranean termite abundance measured by numbers of termites extracted from baits, mass of paper removed from baits, proportion of dung pats attacked, and quantities of surface foraging galleries all indicated that subterranean termites were most abundant in mesquite (Prosopis glandulosa) dune and creosotebush habitats and least abundant in grassland and shinnery oak (Quercus harvardii) habitats. Subterranean termite abundance was not affected by soil stability but by the dominant vegetation. Subterranean termites consumed more than 80\% of the creosotebush leaf litter from litter bags between August and December. There was no evidence that termites consumed shinnery oak leaves or grass stems and leaves.

}, url = {/files/bibliography/697.pdf}, author = {Walter G. Whitford} } @article {51196, title = {Effects of repeated drought on soil microarthropod communities in the northern Chihuahuan Desert}, journal = {Biology and Fertility of Soils}, volume = {28}, number = {2}, year = {1999}, month = {April 1, 1999}, pages = {117-120}, abstract = {

Soil microarthropods were sampled in plots centered on creosotebushes (Larrea tridentata) and in plots centered on mesquite (Prosopis glandulosa) coppice dunes. Nine plots in each area were covered by rain-out shelters with greenhouse plastic roofs which excluded natural rainfall and nine plots received natural rainfall. There were differences in the abundance of several mite taxa in soils from the mesquite coppice dune plots. Some taxa (Stigmaeidae, Nanorchestidae and Entomobryidae) occurred in significantly lower numbers in the soils of the drought plots. Other taxa (Tarsonemidae and Cunaxidae) were more abundant in the drought plots in the mesquite coppice dunes. There were no significant differences in the abundance of any of the dominant taxa of soil microarthropods in the drought and control plots centered on creosotebush. In the creosotebush habitat, there were significantly fewer Prostigmata in the plots exposed to drought. In an area with both creosotebush and mesquire, there were no significant differences in microarthropod population responses to drought and in recovery from drought. The differences in responses of soil microarthropods to drought in creosotebush and mesquite habitats are attributed to the differences in soil stability, litter accumulations, and microclimate associated with the shrubs.

}, keywords = {community, soil microarthropod, drought, soil microarthropod, journal, journals, soil, microarthropod}, doi = {10.1007/s003740050471}, url = {/files/bibliography/99-002.pdf}, author = {Walter G. Whitford and Sobhy, H. M.} } @inbook {51206, title = {Eolian stratigraphy of intrabasinal fault depressions in the northern Hueco and southern TularosaBasins: Evidence for neotectonic activity}, booktitle = {New Mexico Geological Society Guidebook, 49th Field Conference, Las Cruces Country II}, year = {1998}, note = {//LOCAL//LTER III//entered 12/21/2000; update 07/28/2008ProCite field[6]: In}, month = {1998}, pages = {79-86}, publisher = {New Mexico Geological Society}, organization = {New Mexico Geological Society}, abstract = {North-south-trending depressions, which parallel the major boundary faults between the northern Hueco and southern Tularosa Basins and the Franklin, Organ, and San Andres Mountains, have been interpreted as small intrabasinal normal faults. This project excavated and described about 140 profiles, including 81 within 8 intrabasinal fault complexes as part of an archaeological study to determine the late Quaternary stratigraphy within the basin. Our results show 5 major stratigraphic units within the Hueco Basin: La Mesa, eolian analogs of the Jornada (I and II), Isaacks{\textquoteright} Ranch, and Organ deposits, and lastly, the Historic Blowsand deposit. These sediments contain the same morphologic features and have similar radiocarbon ages as sediments along adjacent alluvial fans, indicating that these eolian sediments are time correlative to the extensively-studied deposits along the alluvial fans in the adjacent Desert Project. Morphologic features, isotopic and pollen studies, as well as radiocarbon dates, suggest that the stratigraphy of both types of sediments are controlled by alternating periods of erosion and deposition, which are primarily driven by climatic fluctuations. However, stratigraphic differences along intrabasinal faults suggest some additional local tectonic controls. Understanding the late Quaternary stratigraphy within these basins is crucial for future neotectonic studies. Evidence for seismic activity possibly as recently as the late Pleistocene or early Holocene was found in the form of seismic-induced liquefaction features and fault-related offset of units.}, keywords = {book, books, chapter, chapters, eolian stratigraphy, fault depressions, eolian stratigraphy, geology, Hueco Basin, quaternary geology, report, reports, soil, geomorphology, stratigraphy, Hueco Basin, stratigraphy, Tularosa Basin}, author = {B. J. Buck and Kipp, J. and Curtis H. Monger}, editor = {Greg H. Mack} } @article {51249, title = {Early warning indicators of desertification: Examples of tests in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {39}, number = {2}, year = {1998}, month = {June 1, 1998}, pages = {101-112}, abstract = {

Perennial grasslands that dominated the south-west United States during the past 10,000 years have been desertified to varying extents. Desertification is a temporal phenomenon, defined in this paper as a change in the scale of the spatial distribution of resources. We report here on several indicators of desertification, using bare patch indices as surrogates for direct measures. A bare patch index based on canopy cover, which is relevant for precipitation and wind-driven erosion, is not equivalent to another bare patch index based on soil surface measurements, which is relevant for overland water flow-driven erosion. Per cent grass cover, per cent long-lived grass cover, per cent cover of vegetative reproducers, and a relative preference index all yielded sensitive indicators of desertification. The usefulness of some indicators, such as organic litter, depends upon recent environmental history. Other indicators, such as per cent cover due to grazing-resistant species, appear not to be sensitive to desertification and need further development. Range site type may also be important in determining indicator responses, where some indicators were sensitive to a range site while others were not. Overall, we have identified several sensitive indicators of desertification based on vegetational characteristics in varied range sites in the northern Chihuahuan Desert.

}, keywords = {bare patch index, Chihuahuan Desert, ecosystem health, indicators, litter}, doi = {10.1006/jare.1998.0391}, url = {/files/bibliography/607.pdf}, author = {A.G. de Soyza and Walter G. Whitford and Jeffrey E. Herrick and Justin Van Zee and Kris Havstad} } @article {51212, title = {Effects of volatile compounds on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {76}, year = {1998}, month = {1998}, pages = {228-233}, abstract = {

We examined the effects of six volatile compounds on alfalfa pellet consumption by lambs. In each experiment, 45 lambs were individually fed alfalfa pellets sprayed with a selected compound (camphor, limonene, cts-jasmone, {\^a} -caryophyllene, borneol, or -pinene) at one of five concentrations. Treatment concentrations were multiples (0, .5, 1, 2, and 10) of the concentration of a specific compound (X) that was related to differential herbivory of tarbush by livestock in previous studies. Treatments were applied to alfalfa pellets (.64 kg-lamb^-d"1, DM basis), and consumption was measured during a 20-min interval each morning for 5 d. Lambs were adapted to handling procedures and the pelleted diet (without treatments) for 10 d, Lambs were maintained and fed (approximately 4.5 to 5\% of BW as one group except during 20-min tests. A negative linear effect of treatment concentrations on intake was observed for camphor (P \<.02) -pinene (P\< .01), and a quadratic response was detected for borneol (P \<.02). The other three compounds had no discernible effect on consumption. Although volatile compounds generally had only minor influences on consumption, the negative influences of -pinene and camphor concentrations on pellet consumption suggest that these monoterpenes may partially explain differential herbivory of individual tarbush plants by livestock.

}, keywords = {diets, intake, sheep, terpenoids}, doi = {10.2527/1998.761228x}, url = {/files/bibliography/609.pdf}, author = {Richard E. Estell and E.L. Fredrickson and M.R. Tellez and Kris Havstad and Shupe, W. Larry and D.M. Anderson and M.D. Remmenga} } @article {51238, title = {Effects of soil texture and precipitation on above-ground net primary productivity and vegetation structure across the Central Grassland region of the United States}, journal = {Journal of Vegetation Science}, volume = {9}, number = {2}, year = {1998}, month = {April 1, 1998}, pages = {239-250}, abstract = {

A potentially important organizing principle in arid and semi-arid systems is the inverse-texture hypothesis which predicts that plant communities on coarse-textured soils should have higher above-ground net primary productivity (ANPP) than communities on fine-textured soils; the reverse is predicted to occur in humid regions. Our objectives were: (1) to test predictions from the inverse-texture hypothesis across a regional precipitation gradient, and (2) to evaluate changes in community composition and basal cover on coarse-and fine-textured soils across this gradient to determine how these structural parameters may affect ANPP. Sites were located along a precipitation gradient through the Central Grassland region of the United States: mean annual precipitation ranges from 311 mm/y to 711 mm/y, whereas mean annual temperature ranges from 9 {\textdegree}C to 11 {\textdegree}C.

}, keywords = {Functional type, grasses, Inverse-texture hypothesis, precipitation gradient, Regional analysis}, doi = {10.2307/3237123}, url = {/files/bibliography/627.pdf}, author = {D. R. Lane and D.P. Coffin and W. K. Lauenroth} } @article {JRN54963, title = {Effects of global warming on runoff in mountain basins representing different climate zones}, journal = {Hydrology in a Changing Environment }, volume = {1}, year = {1998}, pages = {133-139}, chapter = {133}, abstract = {

The redistribution of runoff in response to global warming may vary in hydrological years of different character as reported by Rango and Martinec (1998). In the present paper, effects of global warming on snow accumulation, snowmelt and runoff are studied in three North American mountain basins with widely varying climate conditions. Although snowmelt is a result of a complex energy balance in mountain basins, the degree-day approach is used as an effective index of this snowmelt so that the Snowmelt RunoffModel (SRM) can be used to assess the effects of global warming. In order to get a clear picture of the effect of increased temperatures, the total precipitation is left unchanged except for conversion from snow to rain when the warmer temperatures dictate.

}, url = {files/bibliography/Rango1998-05.pdf}, author = {A. Rango and J. Martinec} } @article {51252, title = {Essential oil of Chrysothamnus pulchellus (Gray) Greene ssp. pulchellus}, journal = {Journal of Essential Oil Research}, volume = {10}, year = {1998}, month = {1998}, pages = {201-204}, abstract = {

The essential oil profile of Chrysothamnus pulchellus was examined. Samples were collected from the Jornada Experimental Range in south central New Mexico and GC/MS and retention indices were used to identify 48 oil components. Sesquicineole (22.7\%), β-phellandrene (14.9\%), (Z)-β-ocimene (9.4\%), β-pinene (8.8\%), (E)-β-ocimene (6.4\%), β-caryophyllene (3.3\%), and d-cadinene (2.8\%) were the major components of the steam distilled oil.

}, keywords = {Asteraceae, Chrysothamnus pulchellus, essential oil composition, sesquicineole, β-phellandrene.}, url = {/files/bibliography/521.pdf}, author = {M.R. Tellez and Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @conference {51259, title = {Effects of grazing, shrub removal, and drought on Chihuahuan Desert rodent communities}, booktitle = {International Symposium and Workshop: Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {May 12-16, 1997}, pages = {12}, address = {Tucson, AZ}, abstract = {Responses of rodent populations to grazing, drought, and shrub removal were studied in a replicated, block design experiment in a Chihuahuan Desert grassland which has been invaded by mesquite, Prosopis glandulosa, (early stage desertification). We sampled rodent populations two times each year for 4 consecutive years. Shrub removal, drought, and grazing affected species composition and abundance of rodents. Some species responded to changes in structural components of the ecosystem. (Presence or absence of shrubs and other species were responsive to cattle grazing, drought, or both). Data from the experimental study are compared with rodent community data from a series of sites representing a desertification continuum. This study provides empirical evidence for the usefulness of rodents as indicators of biodiversity values in desertification.}, author = {P.U. Alkon and Walter G. Whitford} } @article {51265, title = {Effects of compensatory growth on population processes: A simulation study}, journal = {Ecology}, volume = {78}, year = {1997}, note = {//??//LTER III//}, month = {1997}, pages = {2378-2384}, abstract = {

The spatial extent of the canopy or root system of a plant is often used as an index of its potential to acquire resources, such as water and nutrients. This has given rise to the area of influence (AOI) and neighborhood concepts for quantifying competitive interactions between neighboring plants. Both are based on a circle of fixed radius centered on a plant, which presupposes that two plants in close proximity are always strong competitors. There is evidence that this is not always the case. In this paper, we present a simple model of plant population dynamics that extends the concept of AOI by considering "compensatory" growth of root systems. The ability of a plant to grow roots into soil zones free of neighbors in response to competitive pressures is expressed by the value of a single parameter, λ. Effects on population attributes resulting from competition in plants with compensatory growth are compared with populations with noncompensatory growth. Simulations show that compensatory plants are better able to utilize available space, have greater biomass, and outcompete noncompensatory plants. The change from a clumped to a regular distribution of individuals due to density-dependent mortality is delayed in noncompensatory plants. These theoretical results suggest that growth plasticity and the resulting asymmetry in space acquisition may play an important role in plant population dynamics.

}, keywords = {article, articles, journal, journals, model, population dynamics, population dynamics, model}, doi = {10.2307/2265900 }, url = {files/bibliography/JRN00236.pdf}, author = {Jacques Brisson and J. F. Reynolds} } @conference {51273, title = {Effect of volatile compounds on intake of alfalfa pellets by sheep}, booktitle = {Journal of Animal Science}, volume = {75 (Suppl 1)}, year = {1997}, month = {1997}, pages = {203}, abstract = {

Six experiments were conducted to examine influences of volatile plant compounds on intake. Compounds were selected based on apparent relationships of tarbush leaf surface chemistry and livestock herbivory in previous studies. Average concentration of selected compounds (C) was 100, 100, 5, 300, 25, and 100 /{\`\i}g/g of tarbush DM for camphor, limonene, cis-jasmone, {\^a}caryophyllene, borneol, and -pinene, respectively. During each experiment, 45 individually penned lambs were fed one of five treatments (multiples of C: OX, .5X, IX, 2X, or 10X) for five consecutive days. Treatments were applied to alfalfa pellets (.64 kg, DM basis), and intake was monitored during a 20 min interval each morning. Lambs were preadapted to handling procedures and pelleted diet (without treatments) for 10 d before experiments began. Lambs were maintained and fed (approximately 5\% of BW) as one group except during 20 min tests. Borneol treatment resulted in intake differences (P \< .04), with intake for the 2X treatment greater than OX, IX, and 10X treatments (P \<\  .10). A treatment effect was also observed for -pinene (P \< .05), with lower intake for the 10X treatment than OX, .5X, or IX treatments. Camphor tended to affect intake (P \< .08), with lower intake for the 10X treatment than OX or IX treatments (P \< .10). Although volatile compounds generally had little influence on intake patterns, reduced intake with increased -pinene (and a similar pattern for camphor) concentration suggests these monoterpenes may partially explain differential herbivory of individual tarbush plants by livestock.

}, author = {Richard E. Estell and E.L. Fredrickson and M.R. Tellez and Kris Havstad and D.M. Anderson and M.D. Remmenga} } @article {51274, title = {Economic feasibility of rangeland seeding in the arid southwest}, journal = {Journal of Range Management}, volume = {50}, number = {2}, year = {1997}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {March 1, 1997}, pages = {185-190}, abstract = {

Results from 6 years of seeding trials in the Chihuahuan Desert indicated that establishment of introduced and native grass species responded directly to soil moisture at the 1.22 cm (0.5 in) depth, soil temperature at the 5.08 cm (2 in) depth, and seedbed preparations of mulching and pits. The economic analysis indicated that seeding is not an advisable financial investment in the region under general circumstances. It also showed that when seeding is deemed necessary the best native species economic alternatives are blue grama [Bouteloma gracilis (H.B.K.) Griffiths] with either no seedbed preparation or with post seedbed preparation of mulch. The best introduced species economic alternative is Lehmann lovegrass (Eragrostis lehmanniana Nees.), with no seedbed preparation.

}, keywords = {economic feasibility, rangeland seeding, seedbed preparation, soil moisture, soil temperature, stand establishment}, doi = {10.2307/4002379 }, url = {/files/bibliography/581.pdf}, author = {Ethridge, D.E. and R. D. Sherwood and R. E. Sosebee and C.H. Herbel} } @article {51276, title = {Effects of ruminant digestion on germination of Lehmann lovegrass seed}, journal = {Journal of Range Management}, volume = {50}, number = {1}, year = {1997}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {January 1, 1997}, pages = {20-26}, abstract = {

Lehmann lovegrass (Eragrostis lehmanniana Nees) seed (germination 96\%, dormant 0\%) was used in 4 experiments to study the potential of sheep as a dispersal agent. Five, 4-year-old, ruminally cannulated wethers were used to examine effects of ruminant digestion on seed recovery and germination. All wethers were ruminally evacuated, and rumens were cleansed and reinoculated with strained ruminal fluid. After a 21-day adaptation to pelleted alfalfa, 4 experiments were conducted. Experiment 1 was designed to test viability of Lehmann lovegrass seeds exposed to ruminal and postruminal digestion. Lehmann lovegrass seed (10 g) was dosed intra-ruminally via ruminal fistula, and total fecal collections made. Of the viable seed ruminally dosed, 37\% germinated within 21 days after recovery. Also, 98 to 100\% of the seed that germinated was recovered within 72 hours of dosing. Experiment 2 was designed to test the influence of ruminal microbial digestion on seed degradation and viability, using in sacco nylon bag techniques. In sacco dry matter disappearance increased linearly from 5.5\% at 3 hours of incubation to 16 \% at 120 hours. Germination of seed was not greatly affected until after 72 hours of ruminal incubation. Experiment 3 was designed to examine the effect of mastication on viability of Lehmann lovegrass seeds. Seeds were mixed with seed-free Lehmann lovegrass straw in a proportion of 1 to 10 (seed to straw) and 10 g fed to each wether. Boli were recovered manually via ruminal fistula. Thirty five percent of the seed fed entered the rumen without damage due to mastication. Experiment 4 compared in vitro techniques and in sacco techniques used to estimate the effect of digestion on seed viability. In vitro incubation techniques yielded similar results as in sacco techniques. We conclude that ruminants are potential disseminating agents of Lehmann lovegrass seed.

}, keywords = {Eragrostis lehmanniana, in vitro digestibility, introduced species, mastication, rumen fermentation, seed dispersal, Seed germination, seeds, selective grazing, sheep, sheep dung}, doi = {10.2307/4002700 }, url = {/files/bibliography/582.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Ksiksi, T. and VanTol, J. and M.D. Remmenga} } @mastersthesis {51280, title = {Environmental controls on nitrogen cycling in northern Chihuahuan Desert soils}, year = {1997}, month = {1997}, pages = {149}, school = {Duke University}, type = {PhD Thesispp}, address = {Durham, North Carolina}, abstract = {This dissertation attempts to estimate the magnitude of inputs and losses of nitrogen from soils in the Jornada basin in the Chihuahuan desert of southern New Mexico. An acetylene reduction assay was used to measure nitrogenase activity (N2 fixation) by soil microorganisms. N2 fixation inputs were low (estimated at <1 g ha-1 y-1), with the highest rates detected in tarbush shrubland and playa soils. Nitrogenase activity was greatest at high levels of soil moisture and carbon availability and inhibited by inorganic nitrogen. A strong linear relationship between the ratio of available nitrogen to phosphorus and nitrogenase activity was not found in Jornada soils. The production and loss of nitric oxide (NO) by nitrifying bacteria was strongly regulated by soil moisture and NH4+ availability. Nitrifiers responded rapidly to watering (10 minutes). NO losses were highest from NH4+ -fertilized black gramma grassland soils (69 ng cm-2 h-1). In situ measurements at 15 sites within the Jornada basin revealed low NO emission from untreated soils, with higher losses detected after rain (max. 4 ng cm-2 h-1). Soil moisture derived from runon may sustain NO emission from playa soils for several days after rainfall. Grassland soils showed net N2O consumption, and N2O fluxes were not affected by increased soil moisture availability. Watering had no immediate effect on N2O fluxes from soils between or adjacent to shrubs, but increased production under shrubs after 4 daily 1-cm watering treatments. Fluxes were also higher under shrub canopies than between shrubs 1-hr after a 1-cm water treatment. The highest N2O fluxes from wet soils in the field (max. 0.4 ng cm-2 h-1) were an order of magnitude lower than past estimates of denitrification in lab-incubated soils. Extrapolated estimates of N trace inputs and losses for the Jornada LTER suggest that soil nitrogen fixation (<1 g N ha-1 y-1) is negligible compared to atmospheric deposition. Mean atmospheric deposition (1988-93) is 0.8 kg N ha-1 y-1 in dryfall and 1.7 kg ha-1 y-1 in wetfall. N2O losses from Jornada soils are higher than NO and NH3 losses, using the flux estimates derived from lab-incubated soils. Annual N trace gas losses are higher from shrubland ecosystems that from grassland (6.2 vs 3.9 kg N ha-1y-1). Total N gas losses from the basin may have increased over the past century, due to the expansion of shrubland. A conceptual model of N trace gas losses from a desert basin is proposed which relates N trace gas emission to soil source availability. During rain storms, soil organic matter, inorganic nutrients and fine soil particles are removed from upland areas in overland flow. The underlying hypothesis of the model is that soil N cycling-- and therefore N trace gas emission-- is highest in topographic depressions, where soil moisture and nutrients accumulate. The relative emission of N2O and NO may be higher in low-lying areas, due to the limited diffusion of NO in fine-textured soils.}, keywords = {dissertation, dissertations, theses, thesis}, author = {Anne E. Hartley} } @article {51305, title = {Essential oil of Dyssodia acerosa DC}, journal = {Journal of Agricultural and Food Chemistry}, volume = {45}, number = {8}, year = {1997}, month = {1997}, pages = {3276-3278}, abstract = {

Samples of the suffrutescent Dyssodia acerosa DC. were collected from the Jornada Experimental Range in south-central New Mexico, and GC/MS and retention indices were used to identify 62 components from the steam-distilled oil. Chrysanthenone (34.8\%), limonene (14.5\%), camphor (12.3\%), α-pinene (6.8\%), sabinene (4.3\%), camphene (3.9\%), (E)-β-ocimene (2.5\%), 1,8-cineole (2.2\%), myrcene (2.0\%), and cis-sabinene hydrate (1.6\%) were the major components of the steam-distilled oil.

}, keywords = {Asteraceae, camphor, chrysanthenone, Dyssodia acerosa, essential oil composition, limonene}, doi = {10.1021/jf9701502}, url = {/files/bibliography/637.pdf}, author = {M.R. Tellez and Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @article {51306, title = {Essential oil of Flourensia cernua DC}, journal = {Journal of Essential Oil Research}, volume = {9}, year = {1997}, month = {November 1, 1997}, pages = {619-624}, abstract = {The leaf oil of Flourensia cernua DC, collected from the Jornada Experimental Range in southcentral New Mexico was analyzed, GC/MS and retention indices were used to identify 89 components. {\^a}-Eudesmol (24.5\%), -eudesmol (6.9\%), limonene (6.6\%), {\~a}-eudesmol (4.6\%), myrcene (3.8\%), borneol (3.3\%), and {\"a}-3-carene (3.0\%) were major components of the steam distilled oil. In an ethanol extract of intact leaves, flourensadiol (44.6\%), artemisia alcohol (5.5\%), viridiflorol (2.7\%), and borneol (2.0\%) were the main components.}, url = {/files/bibliography/97-001.pdf}, author = {M.R. Tellez and Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @article {51375, title = {Effects of plant size on photosynthesis and water relations in the desert shrub Prosopis glandulosa (Fabaceae)}, journal = {American Journal of Botany}, volume = {83}, number = {1}, year = {1996}, month = {1996}, pages = {99-105}, abstract = {

The Jornada del Muerto Basin of southern New Mexico has undergone a marked transition of plant communities. Shrubs now dominate areas that were previously dominated by perennial grasses. The replacement of grasses by shrubs requires an establishment phase where small shrubs must compete with similar-sized grass plants. This is followed by a phase in which established shrubs sequester nutrients and water within their biomass and alter soil resources under their canopy, creating {\textquotedblleft}islands{\textquotedblright} of fertility. We studied gas exchange and water relations of small and large shrubs growing in the Jornada del Muerto as a function of varying soil moistsure during the season. The small shrubs had greater net assimilation, stomatal conductance, transpiration, and xylem water potential than large shrubs following high summer rainfall in July and highest seasonal soil moisture. High rates of carbon assimilation and water use would be an advantage for small shrubs competing with grasses when shallow soil moisture was plentiful. Large shrubs had greater net assimilation and water-use efficiency and lower xylem water potential than small shrubs following a dry period in September when soil moisture was lowest. Low xylem water potentials and high water-use efficiency would allow large shrubs to continue acquiring and conserving water as soil moisture is depleted. Although the study provides evidence of differences in physiological responses of different-sized shrubs, there was not support for the hypothesis that small shrubs are more closely coupled to variation in soil moisture availability than large shrubs. Small shrubs may actually be less coupled to soil moisture than large shrubs and thus avoid conditions when continued transpiration could not be matched by equivalent water uptake.

}, keywords = {Atmospheric moisture, desert soils, deserts, grasses, plants, Rain, shrubs, soil depth, soil water, Water use efficiency}, doi = {10.2307/2445960}, url = {/files/bibliography/471.pdf}, author = {A.G. de Soyza and A. C. Franco and R. A. Virginia and J. F. Reynolds and Walter G. Whitford} } @proceedings {51374, title = {Effects of summer drought on the water relations, physiology, and growth of large and small plants of Prosopis glandulosa and Larrea tridentata}, volume = {General Technical Report INT-GTR-338}, year = {1996}, month = {1996}, pages = {220-223}, publisher = {USDA Forest Service, Intermountain Research Station, Gen. Tech. Rep. INT-GTR-338}, address = {Las Cruces, NM}, abstract = {

Large and small plants of creosotebush and mesquite were subjected to drought during summer 1993. Large and small plants responded to drought with lowered xylem water potential and lowered photosynthetic gas exchange. Large plants appear to maintain a reduced but constant photosynthetic rate during drought, and responded to precipitation with increased photosynthesis. How-ever, small plants attempted to maintain a high photosynthetic rate throughout the season, responding less strongly to \ precipitation events, but probably depleting reserves more and causing photosynthesis to decline more when droughted. Our results suggest that \ large, established plants are better able to withstand drought than are small, establishing shrubs.

}, url = {/files/bibliography/472.pdf}, author = {A.G. de Soyza and Walter G. Whitford and R. A. Virginia and J. F. Reynolds}, editor = {J.R. Barrow and McArthur, E. Durant and R. E. Sosebee and R. J. Tausch} } @proceedings {51326, title = {Economics of rangeland seeding in the Chihuahuan Desert}, year = {1996}, month = {1996}, pages = {1-20}, publisher = {Texas Tech University}, address = {Lubbock, TX}, abstract = {

Data from six years of seeding trials from the Jornada Experimental Range were used to develop relationships for seedling establishment as a function of soil moisture, soil temperature, and-seedbed preparations. These relationships were integrated into an economic evaluation of expected net present value based on probabilities of the occurrence of various environmental conditions. The analysis shows that seeding is not feasible as a financial investment in the region. However, when seeding is considered necessary for other reasons, the least cost native plant species is blue grama (Bouteloma gracilis) with no seedbed preparation and the least cost introduced plant species is Lehmann lovegrass (Eragrostis lehmanniana) with no seedbed preparation. If seeding in the region is to become economically attractive, ways to increase the probability of achieving stand establishment must be found.

}, url = {/files/bibliography/477.pdf}, author = {Ethridge, D.E. and R. E. Sosebee and R. D. Sherwood and C.H. Herbel} } @conference {51328, title = {Effect of domestic animals and precipitation levels on the establishment of Lehmann lovegrass (Eragrostis lehmanniana Nees) seedlings}, booktitle = {Mexican Society for Range Management Meeting}, year = {1996}, month = {August 20-23, 19}, address = {Zacatecas, Mexico}, abstract = {

Lehmann lovegrass is an introduced grass. This grass is a very aggressive competitor and itis not preferred by livestock. As a result, it has invaded areas where it was not sown and displaced native grasses. Now, in some rangelands, it is a problem (Cox and Ruyie, 1986). Wind, water, and animals are means by which seeds arrive and colonize new areas (Fenner, 1985) and the precipitation is a key factor in the establishment of new seedlings. In order to understand the process by which Lehmann lovegrass is being dispersed it is necessary to understand the role that domestic animals and precipitation play in this process. The objective of this study was to evaluate if the domestic animals are dispersing the seed of this grass through its consumption and deposition of the seeds in the feces, and how the precipitation affects the establishment of new seedlings. The study was carried out at the USDA/ARS Jornada Experimental Range located 37 km north of Las Cruces, NM. Two means of seed dispersion were evaluated (seed dispersed through feces and seed broadcasted) under two levels of precipitation [long-term average (average) and long-term average + 50\% (high)]. The broadcasted seed treatments had the highest number of emerged seedlings, averaging 21.9 and 19.9 seedlings m3 for the high and average precipitation levels, respectively. On the other hand, the treatments of seed dispersed through feces produced only 2.7 and 1.4 seedlings m3. At the end of the growing season the mortality rate fluctuated between 80 and 100\%. The amount of rainfall had no effect on the number of established seedlings. In conclusion, the main means of Lehmann lovegrass seed dispersion is the seed broadcasted by the wind. However, the results show that domestic animals also disperse the seed of this grass, contributing to the fast colonization of new areas located far away from the seed source.

}, keywords = {dispersal, domestic animals, Lehmann lovegrass, precipitation, seeds}, author = {Flores, M.A. and E.L. Fredrickson and Pieper, Rex D. and L. W. Murray} } @book {51351, title = {Ecosystem function of biodiversity in arid ecosystems}, series = {Functional roles of biodiversity: A global perspective}, year = {1996}, note = {//NMSU,USDA//LTER-III//ProCite field[6]: InProCite field[30]: Mooney, H. A.Cushman, J. H.Medina, E.Sala, O. E.Schulze, E.-D. , eds.}, month = {1996}, pages = {99-128}, publisher = {John Wiley \& Sons Ltd}, organization = {John Wiley \& Sons Ltd}, address = {New York}, abstract = {Our discussion applies to both so-called hot or semi-tropical deserts and to cool or temperate arid zones; we exclude from discussion the polar deserts, where temperature constrains plant growth during most of the year. We recognize that aridity may arise from different combinations of regional climate, topography, and so on.... In this chapter we focus on a description of the nature and function of biodiversity, at several levels of organization, within these systems.}, keywords = {biodiversity, ecosystem, book, books, chapter, chapters, ecosystem dynamics, abiotic factors, ecosystem dynamics, biotic responses, ecosystem dynamics, invertebrates, ecosystem dynamics, water, ecosystem function, ecosystem, biodiversity, ecosystem, fungal community, ecosystem, plant production, ecosystem, processes, ecosystem, soil microorganisms, grazing, ecosystem function, plant production, report, reports, soil nutrients, soil structure}, author = {L. Huenneke and I. R. Noble} } @article {51357, title = {Effects of Flourensia cernua ingestion on intake, digesta kinetics, and ruminal fermentation of sheep consuming tobosa}, journal = {Journal of Range Management}, volume = {49}, year = {1996}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1996}, pages = {325-330}, abstract = {Tarbush (Flourensia cernua DC.) contributes substantially to the Chihuahuan Desert shrub biomass, but is browsed sparingly by livestock. This study was designed to assess nutritional benefits and/or toxicosis of ingestion of pre-bloom tarbush leaves by sheep fed a low quality native grass diet Sixteen ruminally cannulated sheep (46 kg) housed in individual pens were randomly assigned to 1 of 4 treatments for 28 days. Treatments were ground tobosa grass (Pleuraphis mutica Buckl.) substituted with 0,10, 20, or 30\% (dry matter basis) whole tarbush leaves (19\% CP). At 20 and 30\% of the diet, tarbush increased (P = 0.0049) dry matter intake during week 3, and sheep consuming 30\% tarbush tended to increase dry matter intake during week 2 (P = 0.0559). Dietary tarbush did not affect any variable associated with ruminal fluid kinetics, particulate digesta kinetics, or in situ degradation rates of tobosa dry matter or neutral detergent fiber (P>.05). Molar butyrate proportions (P - 0.0032) and total volatile fatty acid concentrations (P = .0064) were greater for the 30\% tarbush treatments. Ruminal ammonia was greater (P<.0029) at 6,8, and 12 hours postfeeding for the 30\% tarbrush treatment. Sheep lost body weight regardless of treatment; however, sheep not fed tarbush tended (P = 0.0945) to lose more weight Serum clinical profiles (day 0,7,15, and 21) confirmed nutritional stress but did not suggest toxicosis.}, url = {/files/bibliography/496.pdf}, author = {D. King and Richard E. Estell and E.L. Fredrickson and Kris Havstad and Wallace, J.D. and L. W. Murray} } @article {51356, title = {Effects of Flourensia cernua ingestion on nitrogen balance of sheep consuming tobosa}, journal = {Journal of Range Management}, volume = {49}, year = {1996}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1996}, pages = {331-335}, abstract = {

Flourensia cernua DC. (tarbush) is a deciduous shrub with potential as a high-protein forage source for livestock. Twenty-four Polypay x Rambouillet wethers housed in metabolism crates were used to evaluate tarbush as a N source for sheep fed a low quality grass diet. Treatments were 100\% ground tobosa grass (Pleuraphis mutica Buckl.) or tobosa substituted with 10, 20, or 30\% whole pre-bloom tarbush leaves (n = 5) or 26\% ground alfalfa (n = 4, Medicago sativa L.) on a dry matter basis (dmb). Sheep were fed ad libitum for 11 days, after which feed was restricted to 1 \% (dmb) of body weight for 11 days to reduce sorting and maintain uniform intake. Apparent dry matter digestibility was not improved (P = 0.2646) with tarbush or alfalfa. Fecal N was similar (P = 0.1626), but urinary N varied (P = 0.0008) among treatments. Apparent N digestibility differed (P = 0.0042) among treatments (43, 46, 50, 56, and 63\% for sheep consuming 0, 10, 20, or 30\% tarbush or alfalfa, respectively). All treatments resulted in similar (P = 0.1569) but negative N retentions (-2.4, -2.2, -2.8, -2.0, and -1.5 g day-1 for sheep consuming 0, 10, 20, or 30\% tarbush or alfalfa, respectively). Serum clinical profiles (day 22) confirmed all sheep were nutritionally stressed, but did not indicate toxicosis. Although neither tarbush nor alfalfa N compensated for the low quality basal diet, N from 30\% tarbush was utilized with similar efficiency to alfalfa N. The major impediment for using tarbush as a N source appeared to be low palatability.

}, keywords = {alfalfa, blood chemistry, body weight, cholesterol, digestible protein, dry matter, feed intake, Flourensia, grasses, Leaves, New Mexico, nitrogen balance, nitrogen retention, Pleuraphis mutica, sheep, urea, weed palatability}, url = {/files/bibliography/497.pdf}, author = {D. King and E.L. Fredrickson and Richard E. Estell and Kris Havstad and Wallace, J.D. and L. W. Murray} } @article {51373, title = {Effects of restricted suckling on forage intake of range calves}, journal = {Journal of Range Management}, volume = {49}, year = {1996}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1996}, pages = {290-293}, abstract = {

Twenty two-year-old primiparous Angus X Hereford cows and their heifer calves were used to study effects of milk consumption on calf performance, suckling behavior, and forage intake. Ten cow-calf pairs were allotted to each of 2 treatments on blue grama (Bouteloua gracilis [H.B.K.] Lag.) rangeland. Calves from 5 cows were prevented from suckling the rear udder quarters for 4 weeks to reduce milk intake by 32\% when calves averaged 71 +/- 4 days of age. The other 5 calves were allowed to suckle normally. Four 12-day sampling periods were conducted from June through September. Calves from the control treatment weighed more (P \< 0.05) than restricted calves in each period and at weaning. Calves from the restricted treatment did not (P \> 0.10) suckle longer or more frequently than control calves during any sampling period. Forage organic matter intake was not (P \> 0.10) different between cows or calves from either group at any date. Milk production was not different (P \> 0.10) between groups 1 month after restriction periods were terminated. Calves on 4 week milk restriction did not increase forage organic matter intake and had decreased weaning weights compared to control animals.

}, keywords = {blue grama, Bouteloua gracilis, buffalograss, cow, feeding behavior, milk intake, milk restriction, rangelands}, doi = {10.2307/4002585 }, url = {/files/bibliography/503.pdf}, author = {Sowell, B.F. and Wallace, J.D. and Branine, M.E. and Hubbert, M.E. and E.L. Fredrickson and Bowman, J.G.} } @conference {51423, title = {Effects of summer drought on the water relations, physiology and growth of large and small plants of Prosopis glandulosa and Larrea tridentata}, booktitle = {Wildland Shrub Symposium}, year = {1995}, month = {May 23-25, 1995}, pages = {19}, abstract = {Large and small plants of creosotebush (Lorreatridentata) and mesquite (Prosopisglandulosa) were subjected to summer drought by erecting rain-exclusion shelters with transparent plastic roofs over the experimental plants. The root systems of control and experimental plants of both species were isolated from the surrounding soil mass to a depth of approximately 1.5 m, with a backfilled, plastic-lined trench approximately 0.6 m from the plant crown dripline. The rainout shelters were very effective in drying the soil as measured with a neutron atennuation probe at 0.3 and 0.9 m. Both large and small plants responded to drought with lowered xylem water potential and lowered photosynthetic gas exchange, but the gas-exchange physiology of large plants appeared to be somewhat uncoupled from the short-term drought we induced. Stem growth was much greater in control plants, and in experimental plants growth appeared to be greater in small plants than in large plants. Our results are largely consistent with shrub resource islands theory which suggests that large, established plants with greater accumulated resources are better able to withstand episodes of short-term drought than are small, establishing shrubs.}, keywords = {Larrea tridentata, physiology, prosopis glandulosa, summer drought, water relations}, author = {A.G. de Soyza and Walter G. Whitford and A. C. Franco and R. A. Virginia and J. F. Reynolds} } @proceedings {51407, title = {Ecological impacts of plant invasion in rangeland ecosystems}, volume = {BLM/OR/WA/PT-95/048+1792}, year = {1995}, note = {//OTHER//NONE// Updated 12/17/2005ProCite field[2]: Associate ProfessorProCite field[6]: In}, month = {January 17, 1995}, pages = {10-14 pp.}, address = {Held in conjunction with the annual meeting for The Society of Range Management on January 17, 1995}, abstract = { Invasive non-native species, both plants and animals, have become major management problems in North America (OTA 1993). Alien (non-native) plants can have harmful impacts in natural and semi-natural ecosystems as well as in agricultural settings; these "environmental weeds" are the result of both deliberate importations (e.g., for forage crops or as ornamentals) and accident. These importations continue, and the number of problematic species is increasing all the time. The arrival of new species has the potential to alter ecological relationships and processes, with undesirable impacts on management and conservation concerns. The objective of this paper is to review the ecological impacts of invasive non-native plants in natural systems, with a focus on semi-arid rangelands. I will outline measures of ecosystem health in rangelands, and discuss how they can be influenced by invasive plants. I will also present some guidelines for action, based on what we know of the ecology of these invading weeds.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, plant invasion, plant, non-native, proceeding, proceedings, rangeland management, rangeland, ecosystem}, author = {L. Huenneke} } @inbook {51405, title = {Ecosystem function of biodiversity in Arid and semi-arid lands}, booktitle = {Global biodiversity assessment}, year = {1995}, note = {//OTHER//NONE//ProCite field[6]: In}, month = {1995}, pages = {349-354}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge, England}, abstract = {

In arid lands, water availability (precipitation vs. evaporative demand) imposes severe constraints on biological activity. Precipitation is characterized by unpredictability in time and space as well as by low total amounts (Noy-Meir 1974). Semi-arid ecosystems differ from true arid areas in structure and in the rate and regulation of ecosystem processes. We differentiate between these two, and highlight cases of conversion from semi-arid to arid lands (desertification; Verstraete and Schwartz 1991). Biodiversity, reflected in species richness, is moderately high in semi-arid regions and declines with increasing aridity for most taxa (Shmida 1985; Pianka and Schall 1981; O\&$\#$39;Brien 1993). Certain taxa are diverse relative to other biomes (e.g. predatory arthropods, ants and termites, grasshoppers, snakes and lizards, rodents, annual plants), but there is substantial variation in the richness of particular taxa among the deserts of different continental areas. The abundance and activity of desert organisms are \&$\#$39;pulsed\&$\#$39; in correspondence with episodes of high moisture availability (Noy-Meir 1973; Louw and Seely 1982); while the prevalence of dormancy, cryptobiosis, aestivation and other modes of escaping harsh conditions means that most of the biodiversity of arid regions can be impossible to census or sample during most time periods.

}, keywords = {biodiversity, book, books, chapter, chapters, ecosystem, biodiversity, report, reports, water, biodiversity}, author = {L. Huenneke and I. R. Noble}, editor = {V. H. Heywood and Watson, R. T.} } @inbook {51406, title = {Effects of biodiversity on water distribution and quality}, booktitle = {Global biodiversity assessment}, year = {1995}, note = {//OTHER//NONE//ProCite field[6]: In}, month = {1995}, pages = {412-417}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge, England}, abstract = {

Water is essential to all living organisms, and in turn the biosphere plays a crucial role in the transportation, transformation and redistribution of water on local and regional scales. In terrestrial ecosystems, vegetation plays the primary role in transferring water from the soil to the atmosphere; plants and animals also have significant effects on the movement of water into the soil. In terrestrial systems, living organisms often regulate the magnitude and rate of flow of water from one site to another; similar effects occur in some aquatic ecosystems. In both terrestrial and aquatic systems the biota can have measurable impacts on water quality (e.g. on composition of solutes, abundance and nature of particulates). Unfortunately there are few experimental studies exploring the links between biodiversity and water. Clearly, though, differences among organisms and communities in physiology, phenology and structure determine the type and magnitude of biotic effects. The text below summarizes some of the major influences of species and communities on water fluxes and water quality.

}, keywords = {biodiversity, book, books, chapter, chapters, ecosystem, biodiversity, report, reports, water, biodiversity}, author = {L. Huenneke}, editor = {V. H. Heywood and Watson, R. T.} } @conference {51408, title = {Effects of tarbush ingestion on intake, digesta kinetics, in situ digestion, ruminal fermentation, and nitrogen balance of sheep consuming low quality tobosa grass diets}, booktitle = {Journal of Animal Science}, volume = {74 (Suppl. 1)}, year = {1995}, month = {1995}, pages = {Abstract 205}, abstract = {Tarbush (Flourensiacernua) represents a substantial biomass in the Chihuahuan Desert. Two studies were conducted to assess intake, in situ digestion, passage rate, ruminal fermentation, and nitrogen balance of sheep fed a low quality tobosa (Hilariamutica) diet containing up to 30\% tarbush leaves. Tarbush was harvested and air dried, and leaves were separated from stems. In Exp. 1, 16 ruminally cannulated Polypay x Rambouillet lambs (avg BW = 46 kg) were individually fed (twice daily) ground (2.54 cm) tobosa (5.9\% CP, 80\% NDF; DM basis) substitued with 0, 10, 20, or 30\% (DM basis) tarbush (18.9\% CP, 33\% NDF) leaves ad libitum for 28d. In Exp. 2, 24 Polypay x Rambouillet wethers (avg BW = 47 kg) in metabolism crates were allotted to one of the four treatments described above (n = 5) or 26\% ground alfalfa (n = 4). Sheep were fed ad libitum for 11 d and then restricted to 1\% of BW for 11 d to equalize intake. In Exp. 1, DMI for 20 and 30\% tarbush treatments was greater (P = .0049) during week 3 than 0 and 10\% treatments. Molar butyrate proportions (P = .0032) and total VFA concentrations (P = .0064) were greater for the 30\% tarbush treatment than other treatments. Sheep fed 30\% tarbush had greater (P < .0046) ruminal ammonia concentrations than sheep fed other diets at 6, 8, and 12 h postfeeding. In Exp. 2, all treatments resulted in similar but negative N retentions (-2.4, -2.2, -2.8, -2.0, and -1.5 g/d for sheep consuming 0, 10, 20, or 30\% tarbush or alfalfa, respectively). Because only 30\% tarbush elicited measurable responses in Exp. 1 (based on ruminal ammonia dn total VFA concentrations), nutrients contained by tarbush (especially CP) did not appear to be completely available to sheep. Low DMI observed in Exp. 2 was likely due to secondary compounds in tarbush and may partly explain why no differences in N balance were observed in Exp. 2.}, keywords = {intake, nitrogen balance, rumen ammonia, sheep, tarbush ingestion, tobosa grass}, author = {D. King and Richard E. Estell and E.L. Fredrickson and Kris Havstad and Wallace, J.D. and L. W. Murray} } @conference {51410, title = {Examination of sheep as a potential disseminator of grass seed}, booktitle = {48th Annual Meeting of the Society for Range Management}, year = {1995}, month = {1995}, pages = {Abstract 36}, abstract = {Seeds resistant to intestinal and ruminal degradation have potential for dispersal by ruminant livestock. Additionally, very small seeds may have short ruminal retention times and, thus, escape ruminal degradation. Depending on the extent of intestinal degradation, small seeds may remain viable after excretion. These seeds may subsequently benefit from high nutrient and perhaps moisture conditions associated with dung. Five 4-year-old, ruminally cannulated wethers were used to study the effect of buccal, ruminal, and intestinal digestion on seed viability of Lehmann lovegrass. After ruminal evacuation followed by a 21-day ruminal adaptation to pelleted alfalfa, three experiments were conducted. Experiment 1 tested seed viability after ruminal plus post-ruminal digestion. Hydrated seeds were dosed intraruminally and total fecal collections were made. An aliquot of the feces was wet sieved and seeds recovered. Germination rates were then measured. Intact fecal pellets were used to determine seed viability under in situ conditions. Experiment 2 tested the influence of ruminal degradation on seed viability using in sacco techniques. After incremental ruminal incubation up to 120 hours, all intact seeds were isolated and seed viability was measured. Experiment 3 tested the effect of mastication on seed viability. Seeds mexed with seed-free straw in a proportion of 1 to 10 were fed to each wether and boli recovered manually before rinsing and germination rate determinations. These experiments are assisting efforts to determine digestive influences on seed viability of differing plant species. These efforts will provide information necessary to both promote and prevent seed dispersal by domestic livestock.}, keywords = {dissemination, grass seed, seed viability, sheep}, author = {Ksiksi, T. and E.L. Fredrickson and J.R. Barrow and Kris Havstad and Richard E. Estell} } @article {51436, title = {The effect of neighbors on root distribution in a creosotebush (Larrea tridentata) population}, journal = {Ecology}, volume = {75}, number = {6}, year = {1994}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1994}, pages = {1693-1702}, abstract = {We excavated and mapped the lateral extension of 32 creosotebush shrubs (Larrea tridentata) in the Chihuahuan desert of New Mexico to examine the effect of neighborhood interaction on root distribution. The smallest closed-angle polygon encompassing all roots of an individual was taken as a representation of its root system. Several geometrical characteristics of these polygons were measured and compared to interference vectors based on the location and size of the neighbors. We found that root systems were more developed away from the maximum competitive pressure of neighbors. Relation between root system shape and pressure from neighbors was stronger when the competitive vectors were integrating effect from all neighbors. Size of neighbors did not appear to contribute significantly to the relation. The resulting spatial pattern tended to reduce the overlap between neighboring root systems. Two conceptual models of root growth response to neighbors appear to explain our results. Both models assume that when the root system of neighbors meet, root growth is impaired or ceases at the zone of contact. In the non-overlapping, non-compensatory model, the decrease in root growth between two close neighbors is not compensated elsewhere, possibly affecting the overall plant performance. In the non-overlapping, compensatory model, a plant with a close neighbor responds by investing in root growth away from the competitive pressure or simply in zones free of neighbors. Under this model, two plants can be close to each other and not compete. Competition in the population is for space and only occurs when a plant root system is crowded on all sides.}, keywords = {article, articles, competition,Larrea roots, journal, journals, Larrea, root competition, model,neighborhood,Larrea, root competition,Larrea}, author = {Jacques Brisson and J. F. Reynolds} } @article {51439, title = {Effects of organic solvents on use of tarbush by sheep}, journal = {Journal of Chemical Ecology}, volume = {20}, number = {5}, year = {1994}, month = {1994}, pages = {1137-1142}, abstract = {

Tarbush (Flourensia cernua DC) is a native perennial shrub prevelant in many parts of the Chihuahuan desert. Ruminants have exhibited limited use of tarbus leaves and new leaders as a forage during the summer growing season. Efforts to increase use of tarbush by lambs, through spraying with various organic solvents were unsuccessful. probably because of the highly variable response. However, complete immersion of tarbush in organic solvents (acetone and ethanol) increased (P\< 0.01) tarbush use by ram lambs when compared to unaltered tarbush using organic solvents enhanced acceptability of tarbush to sheep.

}, keywords = {Flourensia cernua, herbivory, leaf surface, organic solvents, sheep, tarbush}, doi = {10.1007/BF02059749}, url = {/files/bibliography/416.pdf}, author = {Richard E. Estell and D.M. Anderson and Kris Havstad} } @article {51441, title = {Economic success of range reseeding in an arid environment}, journal = {Texas Tech University, Research Highlights--1994; Noxious Brush and Weed Control, Range and Wildlife Management}, volume = {25}, year = {1994}, month = {1994}, pages = {22-23}, abstract = {

Information from range reseeding experiments from USDA and the Jornada Experimental Range in New Mexico was used to establish relationships for stand establishment for both native and introduced grass species. Major factors determining stand establishment are soil moisture and temperature conditions and seedbed preparation techniques. Costs of seeding were estimated, stand establishment was valued in accordance with its revenue generating potential, and probabilities that conditions needed to achieve different levels of stand establishment were estimated.

}, url = {/files/bibliography/420.pdf}, author = {Ethridge, D.E. and R. E. Sosebee and R. D. Sherwood and Stanaland, B.G. and C.H. Herbel} } @article {51442, title = {Effects of plant size and water relations on gas exchange and growth of the desert shrub Larrea tridentata}, journal = {Oecologia}, volume = {97}, year = {1994}, note = {//NMSU//LTER III//}, month = {1994}, pages = {171-178}, abstract = {

Larrea tridentata is a xerophytic evergreen shrub, dominant in the arid regions of the southwestern United States. We examined relationships between gas-exchange characteristics, plant and soil water relations, and growth responses of large versus small shrubs of L. tridentata over the course of a summer growing season in the Chihuahuan Desert of southern New Mexico, USA. The soil wetting front did not reach 0.6 m, and soils at depth of 0.6 and 0.9 m remained dry throughout the summer, suggesting that L. tridentata extracts water largely from soil near the surface. Surface soil layers (\<0.3 m) were drier under large plants, but pre-dawn xylem water potentials were similar for both plant sizes suggesting some access to deeper soil moisture reserves by large plants. Stem elongation rates were about 40\% less in large, reproductively active shrubs than in small, repoductively inactive shrubs. Maximal net photosynthetic rates (Pmax) occurred in early summer (21.3 u mol m-2 s -1), when pre-dawn xylem water potential (XWP) reached ca. -1MPa. Although both shrub sizes exhibited similar responses to environmental factors, small shrubs recovered faster from short-term drought, when pre-dawn XWP reached about -4.5 MPa and Pmax decreased to only ca. 20\% of unstressed levels. Gas exchange measurements yielded a strong relationship between stomatal conductance and photosynthesis, and the relationship between leaf-to-air vapor pressure deficit and stomatal conductance was found to be influenced by pre-dawn XWP. Our results indicate that stomatal repsonses to water stress and vapor pressure deficit are important in dtermining rates of carbon gain and water loss in L. tridentata.

}, keywords = {article, articles, gas-exchange,Larrea, journal, journals, Larrea,gas-exchange, Larrea,phenology, Larrea,water relations, phenology,Larrea, stomatal conductance,Larrea, water relations,Larrea}, doi = {10.1007/BF00323146 }, url = {files/bibliography/94-Oecologia-Whitford.pdf}, author = {A. C. Franco and A.G. de Soyza and R. A. Virginia and J. F. Reynolds and Walter G. Whitford} } @article {51443, title = {Effects of chronic ingestion of tarbush (Flourensia cernua) on ewe lambs}, journal = {Veterinary and Human Toxicology}, volume = {36}, number = {5}, year = {1994}, month = {1994}, pages = {409-415}, abstract = {

Efforts to increase livestock utilization of tarbush are being coupled with studies to examine tarbush toxicity. Thirty-eight (19/treatment) ewe lambs were assigned at birth to receive either tarbush or alfalfa (15\%, dry matter basis) in a sorghum-based growing ration. Lambs were pen-fed this diet 60 d pre-weaning and 60 d post-weaning. No differences existed between treatments in feed consumption. In the tarbush group, 1 lamb died of unknown causes at 90 d of age, while 3 lambs died between 115 and 120 d of age. There were no deaths in the alfalfa group. Shortly before death, lambs fed tarbush appeared lethargic, disoriented and anorectic. At 122 d of age, 5 lambs were randomly selected from each group. Feces and jugular blood samples were obtained from each lamb before being euthanized and necropsied the following day. All fecal samples were negative for occult blood. Serum gamma glutamyl-transpeptidase (P\  \<\  0.001) and aspartate aminotransferase (P\  \<\  0.001) activities and platelet counts (P\  \<\  0.05) were elevated in lambs fed tarbush, while serum calcium concentrations tended (P\  \<\  0.10) to be greater. Histologic examination revealed diffuse liver apoptosis in lambs fed tarbush. These data indicate tarbush leaves cause liver damage when fed for extended periods of time.

}, keywords = {chronic ingestion, ewe lambs, Flourensia cernua, tarbush}, url = {/files/bibliography/421.pdf}, author = {E.L. Fredrickson and Thilsted, J.P. and Richard E. Estell and Kris Havstad} } @conference {51468, title = {Effect of diet on physical properties of sheep feces}, booktitle = {Annual Meeting, Society for Range Management}, year = {1993}, month = {1993}, pages = {No. 97}, abstract = {Sheep feces{\textquoteright} physical properties were evaluated from two animals fed 100\% tobosa [Hilariamutica (Buckl.) Benth.] diets (HM) and two animals fed 70\% tobosa plus 30\% tarbush (Flourensiacernua D.C.) leaf diets (HM + FC). Preliminary data are presented from a randomized block design involving mature, ruminally cannulated wethers fed daily at 0700 and 1600 h and housed in metabolism facilities with ad libitum access to water and mineral blocks. Fecal samples were obtained from the rectum at 0700 h on days 31, 32 and 33 of the trial and immediately frozen at 0{\textdegree} C. Feces subsampled by day (5 pellets/animal) from two wethers per diet were thawed at room temperature and oven dried at 60{\textdegree} C. Water uptake of individual fecal pellets under vacuum was measured followed by dispersion of individual pellets in distilled water to determine particle size composition in a closed cascade system of soil sieves with an in-line filter. Effluent pH and conductance was determined. Means polled across pellets, days and animals with standard errors were calculated. Fecal pellet water uptake and pH for the HM diet was 248\% +/- 1.53 and 7.67 +/-0.03 compared to 223\% +/- 1.60 and 7.77 +/- 0.02 for the HM + FC diet, respectively. Effluent conductance (mv) for the HM and HM + FC diets was 25.3 +/- 1.51 and -31.2 +/- 1.23, respectively. Based on the mass of five size fractions equalling 100\% of the mass separated, 0.9 +/- 0.22, 8.3 +/- 0.43, 25.5 +/- 0.36, 22.9 +/- 0.37 and 42.3 +/- 0.75 percent of the fecal particles were retained on the 1.18, 0.60, 0.30, 0.150 and Whatman No. 4 sieves/filter, respectively, over both diets. Overall, the mass of 56 intact pellets compared to the mass resulting from summing the five particle size fractions resulted in a 12.2 +/- 1.1\% loss of material.}, author = {D.M. Anderson and Kris Havstad and J. N. Smith and L. W. Murray} } @conference {51467, title = {Evaluating the potential for lambs to bond to heifers}, booktitle = {Annual Meeting, Society for Range Management}, year = {1993}, month = {1993}, pages = {No. 98}, abstract = {Since 1986, two bonded wether sheep on the Jornada Experimental Range (JER) have consistently stayed closer to cattle compared to ewe lambs of similar age and breeding. A joint USDA-ARS ewe-wether sibling study was begun in 1992 to investigate how gender may influence bonding cohesiveness. Purebred Polypay and 1/2 Rambouillet, 1/2 Polypay crossbred sheep were evaluated on the JER, Las Cruces, New Mexico, while purebred Rambouill and 1/4 Finn, 3/4 Columbia or 3/4 Targee crossbred sheep were handled under similar management on the U.S. Sheep Experiment Station, Dubois, Idaho. Lambs were weaned at approximately 60 days of age. Immediately, seven lambs of the same gender and three yearling beef heifers were randomly allocated to one of six pens (three experimental units/gender), each approximately 675 m2 in size, for 60 days using previously described protocol. Pens had a lamb creep area while baled alfalfa in a common bunk was fed ad libitum along with water and mineral blocks. In a 4-h field trial 60 d post pen-confinement, the tendency for lambs to follow the heifers was evaluated by measuring separation of the two animal species and calculating means +/- standard errors to describe cohesiveness. At Las Cruces, wether lambs followed heifers closer (1.45 +/- 0.82 m) than ewe lambs (6.58 +/- 0.82 m; P = 0.001). Idaho lambs did not follow cattle as close as did JER lambs nor did they demonstrate a consistent cohesiveness to stay with cattle. In contrast to JER lambs, Idaho ewe lambs formed a closer association (18.94 +/- 2.87 m) to heifers compared to wethers (29.20 +/- 3.31 m). Lamb cohesiveness to heifers did not appear similar between siblings at either location.}, author = {D.M. Anderson and J.W. Walker and Kris Havstad and L. W. Murray} } @article {51476, title = {Effects of repeated cycles of feed intake shifts on growth, feed efficiency and endocrine profiles of wether lambs}, journal = {Small Ruminant Research}, volume = {10}, number = {2}, year = {1993}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1993. (http://www.sciencedirect.com/science/journal/09214488)}, month = {March 1, 1993}, pages = {103-118}, abstract = {

Fifteen wether lambs (average BW 28.8 {\textpm} 1.8 kg) were used in a 128-d trial to examine effects of cyclical feeding changes on growth, feed efficiency and endocrine profiles. Control lambs were fed a 40\% concentrate diet (40C) at 1.5 {\texttimes} NEm requirement during period 1 (64 d). Another group (1x/2x) was fed 40C at 1 and 2 x NEm in 4-d intervals during period 1; a third group (70/10) 70\% and 10\% concentrate diets in 4-d intervals during period 1. To achieve dry matter intake comparable to controls, 70/10 lambs were fed at 1.79 (70C) and 1.21 (10C) {\texttimes} NEm. All lambs were placed on the control diet during period 2 (32 d) and increased to 2 x maintenance during period 3 (32 d). During period 2, ADG and gain/feed of control lambs tended to be greater (P\<0.10) than for lambs fed alternating treatments. Liver weight as a percentage of hot carcass weight was greater (P\<0.05) for controls than for lambs fed alternating treatments. Hot carcass weight (P=0.07) and dressing percentage (P=0.09) tended to be greater for the 70/10 treatment than for controls. The 1x/2x treatment lowered (P\<0.05) serum cholesterol compared with other groups on d 65, but not on d 0 or 129. Smaller liver weight per unit of hot carcass weight for lambs in the 1x/2x and 70/10 treatments suggests a possible reduction of maintenance requirements.

}, keywords = {Carcass weight, Endocrine profile, feed intake, growth, Lamb}, doi = {10.1016/0921-4488(93)90054-L}, url = {/files/bibliography/398.pdf}, author = {Richard E. Estell and Kris Havstad and Heird, C.E. and E.L. Fredrickson and Hallford, D.M. and Shupe, W. Larry} } @conference {51477, title = {Evaluation of onions as a feed source for growing wethers}, booktitle = {Journal of Animal Science}, volume = {71(Suppl. 1)}, year = {1993}, month = {1993}, pages = {71}, abstract = {A study was conducted to evaluate cull onions as a feed source for growing wethers. An additional objective was to assess toxicity of dietary onions. Fifty-six polypay x rambouillet wethers (average initial BW of 33 kg) were randomly assigned to one of four dietary treatments: (1) 50\% whole sorghum grain (CON), (2) 33\% sorghum: 17\% onions (17\%), (3) 17\% sorghum: 33\% onions (33\%), and (4) 50\% onions (50\%). The remaining 50\% of the diet (DM basis) was pelleted alfalfa (19\% CP). All wethers were pen fed (7 wethers/pan) and treatments were replicated. Each diet was fed for 6 weeks following a 3-week adaptation period to the control diet. Serum was obtained at the end of weeks 0, 1, 3, and 6 to obtain a serum clinical profile (SMAC-25). Body weight did not differ (P > .05) among treatments during the trial. Average gaily gain tended (P = 0.057) to be lower for the 33 and 50\% treatments during weeks 1 and 2 but did not differ (P > .05) from CON during the remainder of the trial (over all ADG are .13, .17, .14, and .11 kg/d for CON, 17, 33, and 50\% treatments, respectively). Packed cell volume tended to be less (P = .057) for 33 and 50\% groups during weeks 1 and 2 and was less (P < .0001) for the same groups during week 3 (34, 33, 29, and 29\% for CON, 17, 33, and 50\%, respectively). Differences in PCV among treatments were not detected (P > .05) for weeks 4, 5, or 6. Serum LDH was elevated (P < .05) for weeks 3 and 6 in sheep eating diets of 33 or 50\% onions. We conclude that under the conditions of this study, onions can be fed safely to sheep and support weight gains similar to those from sorghum grain.}, keywords = {feed source, onions, wethers}, author = {Richard E. Estell and E.L. Fredrickson and Kris Havstad and Shupe, W. Larry and Saar, L.J.} } @conference {51480, title = {Effect of chronic ingestion of tarbush (Flourensia cernua) on the serum chemistry, occult blood and histopathology of ewe lambs}, booktitle = {Annual Meeting, Society for Range Management}, year = {1993}, month = {1993}, pages = {130}, abstract = {

Current efforts to increase livestock utilization of tarbush have been coupled with studies to examine potential tarbush toxicity. To examine the effects of long term ingestion of tarbush by lambs, 38 (19/treatment) ewe lambs were assigned at birth to receive either tarbush or alfalfa (15\%, dry matter basis) in a sorghum-based pelleted creep feed. Lambs were pen-fed this diet 60 days pre-weaning and 60 days post-weaning. No differences existed between treatments in feed consumption. One Iamb died of unknown causes at 90 days of age, while three lambs died between US and 120 days of age. There were no deaths in the alfalfa group. Prior to death lambs appeared lethargic, disoriented and anorectic. At 122 days of age, five Iambs from each treatment were randomly selected from the remaining lambs. Fcces and jugular serum samples were obtained from these animals before necropsy the following day. All fecal samples were negative for occult blood. Serum creatine kinase (P \< .05), gamma glutamyl-transfcrase (P \< .01), aspartate aminotransfcrase (P \< .01), lactate dehydrogenase(P \< .01) and total cholesterol (P \< 0.5) concentrations were elevated in lambs fed tarbush, while conjugated bilirubin concentrations and platelet counts tended (P \< 0.1) to be elevated. Histologic examinations revealed myopathic lesions and diffuse apoptotic liver necrosis in lambs fed tarbush. Interestingly, four out of five lambs fed alfalfa had renal and urinary calculi, while calculi were not found in lambs fed tarbush. These data indicate tarbush will cause muscle and liver damage, with possible secondary cholcstasis when fed for extended periods of time.

}, keywords = {chronic ingestion, ewe lambs, histopathology, occult blood, serum chemistry}, author = {E.L. Fredrickson and Thilsted, J.P. and Richard E. Estell and Shupe, W. Larry} } @article {51483, title = {Effects of four cereal grains on intake and ruminal digestion of harvested forage by beef steers}, journal = {Animal Feed Science and Technology}, volume = {40}, number = {2-3}, year = {1993}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1989. (http://www.sciencedirect.com/science/journal/03778401)}, month = {January 1, 1993}, pages = {93-107}, abstract = {

Effects of grain supplements on intake and digestion of roughage diets have been studied extensively, but studies comparing these effects among different grains are limited. Our experiment compared the effects of four cereal grains on roughage intake and ruminal digestion. Five separately penned ruminally cannulated beef steers (average body weight (BW) 194 kg) were used in a 5 {\texttimes} 5 Latin square design; treatments included prairie hay, or prairie hay plus supplemental barley, corn, sorghum or wheat. Each grain was dry rolled and fed to provide 0.25\% BW as starch to a basal diet of prairie hay (in vitro organic matter digestibility, 56 g 100 g-1; crude protein, 10.8 g 100 g-1 of organic matter). Urea was added to grains to ensure that supplements were isonitrogenous. Grain supplementation did not affect (P\> 0.10) hay organic matter intake, although digestible organic matter intake was increased (P\< 0.10) by supplementation. Ruminal pH was not affected (P\> 0.10) by grain supplementation. Ruminal ammonia-nitrogen was increased (P\< 0.10) by grain supplements containing urea (barley, corn, and sorghum). Ruminal fluid volume and dilution rate was not affected (P\> 0.10) by grain supplementation, nor were particulate passage rate, ruminal or intestinal retention time, or gastrointestinal dry matter fill. Total tract mean retention time was decreased (P\< 0.10) by barley, corn and wheat supplementation, but unaffected (P\> 0.10) by sorghum. A treatment {\texttimes} sampling time interaction (P\< 0.05) was detected for proportions of ruminal acetate and propionate. Acetate was decreased (P\< 0.01) by barley and increased (P\< 0.01) by sorghum. 4 h after supplementation. At 8 h after supplementation, wheat decreased (P\< 0.10) acetate proportions, while sorghum increased acetate proportions (P\< 0.01). Propionate proportions were not affected (P\> 0.10) by treatments. Wheat supplementation increased (P\< 0.01) ruminal butyrate at 2 and 12 h after supplementation, but sorghum decreased butyrate proportions at 2, 8 and 12 h after supplementation. Barley increased (P\< 0.10) total volatile fatty acid (VFA) concentrations at 4 h after supplementation, but VFA concentrations were not affected by other grains. Grain supplementation increased (P\< 0.10) in sacco organic matter disappearance of prairie hay at 48 h of incubation. We conclude that grain supplementation, to provide 0.25\% of BW as starch, did not affect hay intake adversely, and slightly increased in sacco digestion of hay organic matter. More readily fermentable grains (barley and wheat) affected ruminal VFA proportions and concentrations.

}, doi = {10.1016/0377-8401(93)90149-E}, url = {/files/bibliography/402.pdf}, author = {E.L. Fredrickson and Galyean, M.L. and Cheema, A.U. and Beaty, R. and Byrum, G.} } @article {51488, title = {Effect of water and nitrogen additions on free-living nitrogen fixer populations in desert grass root zones}, journal = {Applied and Environmental Microbiology}, volume = {59}, number = {9}, year = {1993}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1993}, pages = {3021-3026}, abstract = {

In this study we measured changes in population levels of free-living N2-fixing bacteria in the root zones of potted Bouteloua eriopoda and Sporobolus fexuosus plants as well as the photosynthetic indices of the plants in response to added nitrogen, added water, and added water plus nitrogen treatments. In addition, N2 fixer population changes in response to added carbon source and nitrogen were measured in plant-free soil columns. There were significant increases in the numbers of N2 fixers associated with both plant species in the water and the water plus nitrogen treatments. Both treatments increase the photosynthetic index, suggesting that plant exudates were driving N2 fixer population changes. Population increases were greatest in the water plus nitrogen treatments, indicating that added nitrogen was synergistic with added water and suggesting that nitrogen addition spared bacteria the metabolic cost of N2 fixation, allowing greater reproduction. Plant-free column studies demonstrated a synergistic carbon-nitrogen effect when carbon levels were limiting (low malate addition) but not when carbon was abundant (high malate), further supporting this hypothesis. The results of this study indicate the presence of N2 fixer populations which interact with plants and which may play a role in the nitrogen balance of desert grasslands.

}, keywords = {article, articles, bacteria, Bouteloua, bacteria, nitrogen fixers, bacteria, Sporobolus, Bouteloua, N2 fixing bacteria, Bouteloua, photosynthesis, Bouteloua, soil nutrients, grass, Sporobolus, grasslands, soil bacteria, journal, journals, Sporobolus, N2 fixing bacteria, Sporobolus, photosynthesis, Sporobolus, soil nutrients}, url = {files/bibliography/JRN00169.pdf}, author = {Peter Herman and Kerri R. Provencio and Ruben Torrez and Seager, Gwen M.} } @article {51494, title = {Effects of variable moisture availability on seed germination in three populations of Larrea tridentata}, journal = {The American Midland Naturalist}, volume = {130}, year = {1993}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1993}, pages = {75-82}, keywords = {article, articles, germination,Larrea seed, journal, journals, Larrea,seed germination, seed, germination}, author = {K. McGee and Marshall, D. L.} } @mastersthesis {51498, title = {Effects of grazing intensity and season of grazing on cow diets and plant responses on northern Chihuahuan desert}, year = {1993}, note = {//??//NONE//}, month = {1993}, pages = {50}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle grazing,diet, cattle grazing,plant response, dissertation, dissertations, theses, thesis}, author = {Nsinamwa, Mackenzie} } @mastersthesis {51501, title = {Estimating and modelling stemflow and throughfall on creosote (Larrea tridentata) in an arid environment}, year = {1993}, note = {//NMSU//LTER II//}, month = {1993}, pages = {43}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Creosote bush (Larrea tridentata) is one of the most common plants in the desert southwestern United States. The purpose of this study was to estimate stemflow and throughfall percentages, try to predict stemflow values, observe whether or not dryfall adds significantly to the ionic nutrients in stemflow, and to explore the relationship between branch angle and percentage of stemflow in an arid environment. To address these concerns several methods including calculating percentages, multiple regression, and paired t-tests were employed. It was found that the average stemflow rate was 16.8 percent while the average throughfall rate was 64.7 percent. The multiple regression produced several important variables in predicting stemflow including mean branch angle, mean branch length, total branch surface area, and canopy area. It seemed obvious during the analysis that several important variables were not included since they were unavailable. It was shown that dryfall does add significantly to the ionic nutrients in stemflow, especially nitrogen which is the most important nutrient for desert plants. No highly significant relationships was found in this study between branch angle and percentage of stemflow.}, keywords = {dissertation, dissertations, Larrea,stemflow model, model,Larrea,stemflow, model,Larrea,throughfall, nutrients,Larrea,stemflow, stemflow, shrub, theses, thesis}, author = {P.M. Rice} } @conference {51505, title = {Effect of feeding ewe lambs a 15\% tarbush pellet pre-and post-weaning on subsequent diet selection of tarbush}, booktitle = {46th Annual Meeting of the Society for Range Management}, year = {1993}, month = {1993}, pages = {No. 131}, abstract = {

Tarbush, a deciduous shrub, has rapidly increased its dominance in Chihuahuan Desert grasslands. Encroachment of tarbush has led to a concomitant degradation of forage production, wildlife habitat value, soil stability and watershed quality. Therefore, sustainable methods to reduce the encroachment of tarbush are highly desirable. Since tarbush is comparable to alfalfa in nutrient density, we believe increasing livestock intake of tarbush will improve diet quality, while decreasing tarbush competitiveness. A sheep study was initiated to determine dietary preference for tarbush and influence of previous tarbush exposure on preference. Twenty ewe lambs (10/treatment) were assigned at birth to receive cither tarbush or alfalfa (15\%, dry matter basis) in a sorghum-based pelleted creep feed. Lambs were pen-fed this diet 60 days pre-weaning and 60 days post-weaning. No differences existed between treatments in ration consumption. After 120 days, each group was placed in one of two adjacent 45 m2 paddocks dominated by tarbush and burrograss (Scleropogon brevifolius). An assessment of individual diet selection was determined visually from an elevated platform at three minute intervals for 4 hours following sunrise on 2 consecutive days, with lambs being alternated to the other paddock on the second day. The observations were repeated every 30 days until dormancy of tarbush. Between each observation period, lambs were pastured in 10 ha paddocks with a similar species composition as the study paddocks. Over the course of the study, lambs were recorded eating tarbush during approximately 35\% of feeding observations. Initially, previous exposure to tarbush appeared to avert lambs from tarbush, yet this aversion wan not apparent during later periods.

}, keywords = {diet selection, ewe lambs, tarbush pellet}, author = {Shupe, W. Larry and E.L. Fredrickson and Kris Havstad and Richard E. Estell} } @mastersthesis {51508, title = {Effect of genetic composition of beef cattle on diet selection on southern New Mexico rangeland}, year = {1993}, note = {//??//NONE//}, month = {1993}, pages = {96}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle,breeding, cattle,diet, dissertation, dissertations, genetics,cattle diet, theses, thesis}, author = {Walker, Derek A.} } @article {51531, title = {Effects of age and flock size on flocking behavior in Rambouillet and Rambouillet x Polypay female sheep}, journal = {Sheep Research Journal}, volume = {8}, number = {3}, year = {1992}, month = {1992}, pages = {112-115}, abstract = {

Although intraspecies cohesiveness or flocking behavior in some breeds of adult sheep is well recognized (Hunter,1960), age effects and numbers of sheep within and among ages independent of maternal attachment is not clear. Young ewe lambs from our New Mexico flock just weaned from their dams refused to stay with a group of adult ewes bonded to cattle (flerd). In contrast, a group of yearling ewes tenaciously stayed close to peer yearling ewes bonded to cattle (Anderson et al.,1988). In attempts to increase the numbers of young bonded lambs in flerds we observed that when group size approached or exceeded 12, lambs frequently became independent of cattle and formed small independent lamb groups. However, when the original small confinement groups were maintained as separate units until the lambs were 6 months or more of age, the small flerd could be combined into larger groups and would maintain close affinity quite consistently (Hulet,1989). Bonded older lambs, yearlings and mature ewes have been maintained in large groups (\>80) with cattle with consistent close affinity of the sheep to cattle over long periods of time (\>3 years). These contrasting behaviors raised the question as to the age at which the flocking instinct, independent of maternal attachment, expresses itself.

}, keywords = {behavior, flocking, management, sheep}, url = {/files/bibliography/390.pdf}, author = {Clarence V. Hulet and D.M. Anderson and Shupe, W. Larry and L. W. Murray} } @mastersthesis {51541, title = {Effects of sex, genetic potential, and season on botanical composition of cattle diets}, year = {1992}, note = {//??//NONE//}, month = {1992}, pages = {88}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {cattle, diet, diet,cattle, dissertation, dissertations, grazing management,cattle diet, grazing,cattle diet, theses, thesis}, author = {Mohammad, Ayed Ghaleb} } @article {51543, title = {Estimation of vegetative cover in an arid rangeland based on soil-moisture using cokriging}, journal = {Soil Science}, volume = {154}, number = {1}, year = {1992}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1992}, pages = {25-36}, abstract = {

Soil moisture and vegetative cover (ephemeral, perennial forb and perennial grass) were measured at 30-m intervals along a 2730-m transect. The spatial correlation of vegetative cover and oil moisture, and their cross-correlations, were examined. A total of 610 estimates of vegetative cover were generated at 3-m intervals along the transect, using both ordinary kriging and cokriging methods. Jackknifed estimates of mean-reduced error and reduced variance were used to validate the cokriging models. The average kriging and cokriging variances and the mean sum of squares (SSQ) were sued to compare the two methods. Based on SSQ comparisons, cokriging is the best method to estimate spring ephemeral cover (for observations form all stations) and perennial spring grass cover (for observations form alternate stations). Cokriging estimations for spring perennial grass cover and for spring ephemeral cover produced 7.14 and 2.13\%, respectively, improvement of kriging. Cokriging gave better estimations when the number of observations for perennial spring grass cover and fall perennial forb and perennial grass covers were decreased.

}, keywords = {article, articles, cokriging, cokriging,vegetative cover, journal, journals, kriging, rangeland, soil moisture,cokriging, technique, cokriging, technique, kriging, transect, vegetative cover}, doi = {10.1097/00010694-199207000-00004}, author = {M. S. Nash and Toorman, Alex and Peter J. Wierenga and Gutjahr, Allan and Gary L. Cunningham} } @article {51545, title = {The effect of polyacrylamide on grass emergence in south central New Mexico}, journal = {Journal of Range Management}, volume = {45}, number = {3}, year = {1992}, note = {//USDA//NONE//}, month = {1992}, pages = {296-300}, abstract = {Seeding rangeland is a challenge for rangeland scientist, especially on those soils with tendency to crusting. Although some information is available on how soil conditioners affect emergence of certain comestible crops, little is known about the effect of synthetic organic matter on grass emergence. We examined the effect of polyacrylamide, a soil conditioner, on seedling emergence of blue panicgrass (Panicum antidotale Retz.), King Ranch bluestem (Bothriochloa ischaemum [L.] Keng), sideoats grama (Bouteloua curtipendula [Michx.] Torr.), plains bristlegrass (Setaria macrostachya H.B.K.), and {\textquoteright}salado{\textquoteright} alkali sacaton (Sporobolus airoides [Torr.] Torr.) under field conditions. Emergence of blue panicgrass and sideoats grama was increased with polyacrylamide applications, even at the lowest concentrations (10 kg ha-1) during summer 1987. No emergence response to polyacrylamide applications was found for King Ranch bluestem, and plains bristlegrass did not emerge in any experimental plots during summer 1987. During summer 1988, blue panicgrass and sideoats grama emergence was again increased with polyacrylamide applications. Emergence of {\textquoteright}salado{\textquoteright} alkali sacaton and King Ranch bluestem was unaffected by polyacrylamide applications. Soil conditioners may be a feasible alternative for seeding some rangeland in areas where crusting is a problem.}, keywords = {article, articles, grass emergence, polyacrylamide, journal, journals, polyacrylamide, seeding,soil conditioner, soil conditioner, grass emergence, soil conditioner, polyacrylamide}, author = {Rubio, H. O. and Wood, M. K. and Manual Cardenas and Buchanan, B. A.} } @proceedings {51550, title = {Effects of climate change on soil biotic communities and soil processes}, volume = {124-136}, year = {1992}, note = {//??//LTER II//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: In}, month = {1992}, publisher = {Yale University Press}, keywords = {abstract, abstracts, climate, soil biota, climate, soil processes, community, soil biota, community,soil biotic, conference, conference proceedings, conferences, proceeding, proceedings, soil processes}, author = {Walter G. Whitford}, editor = {Petters, R. L. and Lovejoy, T. E. (eds.)} } @article {51555, title = {Effects of milk intake on forage intake and performance of suckling range calves}, journal = {Journal of Animal Science}, volume = {69}, year = {1991}, month = {1991}, pages = {899-904}, abstract = {

A study to examine the relationships between milk intake, forage intake, and performance of Hereford-Angus suckling range calves was conducted during July, August, and September of 1984 and 1985. Twenty calves were used each year. The study was conducted at the Red Bluff Research Ranch located 56 km west of Bozeman, Montana. Average daily gain, milk intake (MI), forage digestibility, and fecal output (FO) were measured at 28-d intervals, beginning when the average calf age was 66 +/- 4 d. Milk intake was estimated using weigh-suckle-weigh techniques. Total fecal collections were used to measure FO. Forage digestibility and rates of passage were determined using nylon bag in situ techniques and external markers in ruminally cannulated calves of the same age. Fecal output by calves increased as body weight and age increased. Milk intake was higher (P\< .05) in 1985 than in 1984, but FO was higher (P\< .01) in 1984 than in 1985. Fecal output by calves was negatively correlated to MI in July (r = -.62; P\< .05) and August (r = -.56; P\< .05). No significant correlations were detected between MI and ADG (P\> .10). Forage intake estimates were derived from FO, rate of passage, and in situ digestibility values. During July, calves consumed .3 kg more forage for each kilogram of reduction in fluid MI (P\< .05). In both August and September, calves consumed .6 kg more forage for each kilogram of reduction in fluid MI (P\<.10). Calves maintained similar digestible energy (DE) intake both years, although the source of DE varied.

}, keywords = {calves, forage, intake, Milk, suckling}, url = {/files/bibliography/707.pdf}, author = {Ansotegui, R.P. and Kris Havstad and Wallace, J.D. and Hallford, D.M.} } @conference {51562, title = {Effect of cyclic feeding patterns on growth, serum metabolites and hormones, organ size and carcass traits of wether lambs}, booktitle = {American Society of Animal Science}, year = {1991}, month = {1991}, pages = {No. 839}, edition = {69 (Suppl. 1)}, abstract = {A study using 15 wether lambs (avg wt of 28.8 kg) was conducted (eight 16-d periods, five lambs/treatment) to examine effects of cyclic intake of dry matter or energy density. During the first four periods, controls received a 40\% concentrate diet (40C) at 1.5 x NE., another group (1X/2X) received 40C at 1 and 2 x NE, in 4-d intervals and a third group (70/10) received 70 and 10\% concentrate diets in 4-d intervals. All lambs were fed the control diet during periods 5 and 6 and increased to 2 x maintenance during periods 7-8. Blood samples were collected on d 0, 65 and 129. During periods 5-6, average daily gain and gain:feed ratio of the control group were greater (P < .10) than cyclic treatments. During periods 1-4, a trend existed for the 1X/2X treatment to have higher average daily gain (P = .15) and gain:feed (P = .12) than controls. Liver wt (hot carcass wt basis) was higher (P < .05) for controls. Hot carcass wt (P = .07) and dressing percentage (P = .09) tended to be higher for the 70/10 treatment than controls. Alternated feeding patterns resulted in no major shifts in GH, insulin, triiodothyronine or thyroxine profiles compared with controls. The 1X/2X treatment resulted in lower (P < .05) serum cholesterol than the other groups on d 65 but not on d 0 or 129. Smaller liver wt per unit of carcass wt with the 1X/2X and 70/10 treatment suggests a possible reduction of maintenance requirements.}, keywords = {feeding patterns, growth, lambs, organ mass}, author = {Richard E. Estell and Kris Havstad and Heird, C.E. and E.L. Fredrickson and Hallford, D.M. and Shupe, W. Larry} } @proceedings {51563, title = {Effects of monensin supplementation on grazing beef cattle}, volume = {70 (12)}, year = {1991}, month = {1991}, pages = {6-7}, author = {E.L. Fredrickson and Galyean, M.L.} } @conference {51571, title = {Environmental effects on behavior and production of range cows on the Chihuahuan Desert}, booktitle = {Annual Meeting of the Society for Range Management}, year = {1991}, month = {1991}, pages = {No. 88}, abstract = {

Behavior of free-ranging cows was investigated as affected by season, diurnal periods, and weather parameters. Sixteen genetically diverse lactating cows were fitted with vibracorders to record active time continuously from 18 May 1989 to 3 January 1990. Total collection time was divided into three seasons: hot-dry (1 June to 12 July), warm-rain (1 August to 11 September), and cold-dry (1 November to 12 December). Days within seasons were divided into 24 1-hour periods. Differences in active time were found among seasons (P \< .05), periods (P \< .05), periods within seasons (P \< .05), and cows within periods within seasons (P \< .05). Activity was lowest during the hot-dry season during darkness. Substantial activity occurred during the hottest daytime periods. Warm-rain season activity during darkness increased (P \< .05) slightly with daytime period activity increasing substantially (P \< .05). Cold-dry season activity illustrated classical grazing periods with major post-dawn, pre-dusk, and nighttime period activity. Average total daily active times were 10.9 h, 12 h, and 9.5 h for hot-dry, warm-rain, and cold-dry seasons, respectively. Cows were very active during the hot periods of the day during the hot-dry season. Lowest total active time occurred during the cold-dry season when cows were not lactating and had low physiological requirements.

}, keywords = {behavior, Chihuahuan Desert, environmental effects, production, range cows}, author = {Horton, J. and Pieper, Rex D. and Kris Havstad and Wallace, J.D. and L. W. Murray} } @mastersthesis {51574, title = {Evaluation of hydraulic roughness coefficient from field and laboratory data}, year = {1991}, note = {//NMSU//NONE//}, month = {1991}, pages = {147}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {Rainfall simulation experiments were performed on a number of 1 m by 1 m plots in the field using rainfall simulator at sites throughout New Mexico and eastern Arizona. Using a point frame device, data were collected on the roughness and cover of each plot. From equilibrium condition hydrographs, hydraulic roughness coefficients were calculated for each plot. The hydraulic roughness coefficient was then related to different surface characteristics and flow variables. Total surface cover density, surface random roughness, and flow Reynold{\textquoteright}s number were found to be the main variables affecting hydraulic roughness coefficient with total surface cover density as the single most important variable.}, keywords = {dissertation, dissertations, hydrology, hydraulic roughness, hydrology, rainfall simulation, rainfall simulation, hydraulic roughness, theses, thesis}, author = {Jorat, Saeed M.} } @mastersthesis {51575, title = {Evaluation of range beef cattle production efficiency under semi-desert conditions}, year = {1991}, note = {//??//NONE//}, month = {1991}, pages = {111}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {cattle, production efficiency, dissertation, dissertations, theses, thesis}, author = {Kattnig, Robert M.} } @article {51592, title = {Ecophysiology of the polyploid shrub Atriplex canescens (Chenopodiaceae) growing in situ in the Northern Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {21}, year = {1991}, note = {Full Article from Journal of Arid Environments posted on this website with permission from Elsevier. http://www.sciencedirect.com/science/journal/01401963}, month = {1991}, pages = {45-57}, abstract = {

Diurnal profiles of gas exchange, leaf temperature, and stem xylem pressure potentials were measured at three field sites where plants representative of diploid (2n = 18), tetraploid (2n = 36) or hexaploid (2n = 54) cytotypes of fourwing saltbush (Atriplex canescens) occurred together in various combinations. Results indicated that differences among cytotypes in leaf morphology were related to differences in leaf temperatures, net photosynthesis, leaf conductances, and internal C02 concentrations. Mean area per leaf for diploids was 0{\textperiodcentered}228 cm2, for tetraploids 0{\textperiodcentered}427 cm2, and for hexaploids 0{\textperiodcentered}613 cm2. Leaf temperatures of diploids were consistently 1-5{\textdegree}C higher than the other cytotypes. In contrast, leaf temperatures of hexaploids were at or below ambient levels while leaf temperatures of tetraploids were intermediate to the other cytotypes. Photosynthetic rates of diploids decreased rapidly when leaf temperatures approached 37{\textdegree}C, and 63\% of the variation of photosynthesis was accounted for by leaf temperatures. Increasing internal C02 levels in diploids indicated internal limitations to C02 uptake in the mesophyll were responsible for depressed photosynthesis. In contrast, photosynthesis of tetraploids and hexaploids was largely unaffected by leaf temperatures. Higher leaf temperatures in diploids were also translated into higher conductances and lower water-use efficiency (WUE) than the other cytotypes. Tetraploids and hexaploids had higher WUE that were related to either lower conductances, increased photosynthesis, or a combination of reduced conductances and higher photosynthesis. The intermediate leaf form and physiology of tetraploids may represent a compromise to diploids and hexaploids.

}, url = {/files/bibliography/375.pdf}, author = {R.S. Senock and J.R. Barrow and Gibbens, Robert P. and C.H. Herbel} } @mastersthesis {51594, title = {Effects of biostimulation and method of development on cyclicity, conception rates and age at calving in beef heifers}, year = {1991}, note = {//??//NONE//}, month = {1991}, pages = {57}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle,biostimulation, cattle,breeding, cattle,reproduction, dissertation, dissertations, reproduction,cattle, theses, thesis}, author = {Stuart A. Taylor} } @mastersthesis {51603, title = {Effect of genotype of cow on production and efficiency of beef cattle raised under semidesert, southwest range conditions}, year = {1990}, note = {//??//NONE//}, month = {1990}, pages = {79}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle, breeding, cattle, productivity, dissertation, dissertations, theses, thesis}, author = {Ballard, R.} } @article {51610, title = {Evaluation of a continuous-release ytterbium bolus}, journal = {Journal of Range Management}, volume = {43}, number = {2}, year = {1990}, month = {1990}, pages = {144-147}, keywords = {beef steers, continuous marker, fecal output, ytterbium}, url = {/files/bibliography/90-001.pdf}, author = {Richard E. Estell and Freeman, A.S. and Galyean, M.L. and Wallace, J.D.} } @article {51623, title = {The effects of ruminal escape protein or fat on nutritional status of pregnant winter-grazing beef cows}, journal = {Journal of Animal Science}, volume = {68}, year = {1990}, month = {1990}, pages = {1743-1750}, abstract = {

This study was designed to determine the influence of soybean meal supplementation, with or without additional ruminal escape protein or fat, on the nutritional status of pregnant winter-grazing beef cows. During two winters (Trials 1 and 2), approximately 60 prepartum beef cows grazed native foothills range each year. Cows were allotted randomly to five groups and supplemented (g/d) with either none (control); 570 soybean meal (SOY); 450 soybean meal plus 230 blood meal (SOY + BM); 140 soybean meal, 16 urea plus 450 corn gluten meal (SOY + CGM); or 570 soybean meal plus 210 animal fat (SOY + FAT). These supplements were designed to supply similar quantities of ruminal degraded protein while varying in escape protein quantity and source (SOY + BM and SOY + CGM). Condition scores and body weights were determined at trial initiation (mid-December) and conclusion (early March). Eight blood samples obtained over 4 d during three periods (9, 4 and 1 wk prior to parturition) were analyzed for concentrations of glucose, urea nitrogen (N), total bilirubin, creatinine, albumin, total protein and cholesterol. Cows in the control treatment experienced the greatest BW loss in both trials. In Trial 2, escape protein tended to decrease (P\<.06) BW loss compared to SOY, though loss tended to be greater (P\<.08) with SOY + CGM than with SOY + BM. Escape protein can enhance nutritional status when supplemented with .6 kg/d of soybean meal.

}, keywords = {beef, blood chemistry, cattle, protein supplements}, url = {/files/bibliography/703.pdf}, author = {Miner, J.L. and M.K. Petersen and Kris Havstad and McInerney, M.J. and Bellows, R.A.} } @article {51660, title = {Effect of eliminating subterranean termites on the growth of creosotebush, Larrea tridentata}, journal = {The Southwestern Naturalist}, volume = {34}, number = {4}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {549-551}, abstract = {

Soils devoid of termites are more compacted (Elkins et al., 1886), and nitrogen concentrations in the soil surface decrease with depth. This should affect the growth of deep-rooted shrubs. We studied the effects of water supplementation and termite removal on shoot growth of the common Chihuahuan Desert shrub Larrea tridentata to test the hypothesis that reduced infiltration by removal of termites would reduce growth rates of the shrub.

}, keywords = {article, articles, journal, journals, Larrea,termite effect on growth, termite, Larrea productivity, termite, removal of, water amendment, water infiltration,termite}, doi = {10.2307/3671517}, url = {files/bibliography/89-SWNat-Whitford.pdf}, author = {Julio R. Gutierrez and Walter G. Whitford} } @article {51669, title = {Ecology of fast-growing and slow-growing mesquite nodulating rhizobia in Chihuahuan and Sonoran desert ecosystems}, journal = {Soil Science Society of America Journal}, volume = {53}, number = {2}, year = {1989}, note = {//NMSU, USDA//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {543-549}, abstract = {

Prosopis glandulosa (mesquite) is effectively nodulated by both fast-growing (FG) and slow-growing (SG) rhizobia. The distribution of indigenous, free-living, FG and SG rhizobia, and their morphological and symbiotic characteristics associated with the rooting systems of mesquite were investigated. The three warm desert ecosystems studied were an arroyo, a sand dune, and a playa in the Chihuahuan Desert of New Mexico, and a sand dune and playa in the Sonoran Desert of southern California. The FG rhizobia dominated free-living rhizobial population from 0- to 8-m depth, at the New Mexico playa. In contrast to the New Mexico playa, the surface 1 m soil under mesquite at the California playa was dominated by SG rhizobia, otherwise FG rhizobia dominated to 9-m depth. Slow-growing rhizobia dominated the lowest depths of the mesquite rooting system in both playas. Slow-growing rhizobia dominated the entire rooting zone of both sand dune ecosystems. Fast-growing rhizobia dominated the upper 2 m and SG rhizobia dominated below 2 m in the mesquite rooting zone at the New Mexico arroyo. Regression analysis indicated that the distribution of FG and SG rhizobia was related to the concentration of total soil salts (electrical conductivity) (r2 = 0.20). Chi-square analysis of the distribution of colony morphologies indicated distinct rhizobial populations in each ecosystem. The FG rhizobial population at the New Mexico playa was highly effective and had a high frequency of Hup+ phenotypes. The FG rhizobia isolated from the arroyo were, in contrast, less effective and had a low frequency of Hup+ phenotypes. The SG rhizobial population at the New Mexico dune system was, in contrast, mainly ineffective and had a low frequency of Hup+ phenotypes. The relationship between the variable distribution of FG and SG rhizobia and environmental factors associated with the ecosystems is discussed.

}, keywords = {article, articles, journal, journals, Prosopis, rhizobia, rhizobia, Prosopis-nodulating}, url = {files/bibliography/JRN00093.pdf}, author = {Jenkins, Michael B. and R. A. Virginia and W. M. Jarrell} } @article {51671, title = {The effect of water and nitrogen amendments on photosynthesis, leaf demography, and resource-use efficiency in Larrea tridentata, a desert evergreen shrub}, journal = {Oecologia}, volume = {80}, year = {1989}, month = {1989}, pages = {341-348}, abstract = {

In the Chihuahuan Desert of southern New Mexico, both water and nitrogen limit the primary productivity of Larrea tridentata, a xerophytic avergreen shrub. Net photosynthesis was positively correlated to leaf N, but only in plants that received supplemental water. Nutrient-use efficiency, defined as photosynthetic carbon gain per unit N invested in leaf tissue, declined with increasing leaf N. However, water-use efficiency, defined as the ratio of photosynthesis to transpiration, increased with increasing leaf N, and thus these two measure of resource-use efficiency were inversely correlated Resorption efficiency was not significantly altered over the nutrient gradient, nor was it affected by irriation treatments. Leaf longevity decreased significantly with fertilization although the absolute magnitude of this decrease was fairly small, in part due to a large background of insect-induced mortality. Age-specific gas exchange measurements support the hypothesis that leaf aging represents a redistribution of resources, rather than actual deterioration or declining resoruce-use efficiency.

}, keywords = {Larrea tridentata, leaf demography, nutrient resportion, nutrient-use efficiency, photosynthesis, water-use efficiency}, doi = {doi:10.1007/BF00379035}, url = {/files/bibliography/350.pdf}, author = {Kate Lajtha and Walter G. Whitford} } @article {51673, title = {Effects of water, nitrogen and sulfur amendments on cover, density, and size of Chihuahuan Desert ephemerals}, journal = {Journal of Arid Environments}, volume = {16}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {35-42}, abstract = {

The generality of the water-limited-nitrogen-regulated plant growth hypothesis for desert ecosystems was tested by applying water, nitrogen and sulfur amendments in a complete factorial design to three Chihuahuan Desert ecosystems. Water was added every 2 weeks at a rate to about double the long-term annual precipitation average of 225 mm and nitrogen and sulfur were added once in May 1983 (10 g/m2). Living-canopy area of all herbaceous plants was measured monthly (from April 1983 to December 1984). Since plants can respond to water and nutrients either by establishing more, but smaller, plants or by growing fewer, but larger, plants, density and plant size were measured (once, in me-April 1984). Only C3 winter-ephermerals significantly changed in cover, density or plant size in response to the amendments; no significant responses were observed in C4 summer-ephemerals or perennial grasses and forbs. Species that significantly increased in density did not significantly increase in size and vice versa. Water tended to limit the number (richness) and density of species, whereas nitrogen regulated plant growth (size). Sulfur generally reduced soil pH and species density. This study demonstrated that these general plant responses to increased water and nutrients were highly species and site specific.

}, keywords = {article, articles, ephemeral, also SEE , ephemeral, nutrients, fertilization, also SEE , journal, journals, nitrogen amendment, ephemerals, nutrient amendment, ephemerals, sulfur amendment, ephemerals, water amendment, ephemerals}, doi = {10.1016/S0140-1963(18)31045-0}, url = {files/bibliography/JRN00097.pdf}, author = {J. Ludwig and Walter G. Whitford and Joe M. Cornelius} } @article {51681, title = {Effects of nitrogen amendment on annual plants in the Chihuahuan Desert}, journal = {Plant and Soil}, volume = {120}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {225-231}, abstract = {

Effects of nitrogen amendments on spring annual plant distribution, primary production, and species diversity in a semi-arid environment were studied. The ecological responses of spring annual plant species to nitrogen differed between species, and between sites. The distribution of each species in a control transect was wider than in a nitrogen-treated transect. Annual plant species diversity at each station in the control transect was higher than that of the nitrogen-treated transect. The lower site of the Lower Basin Slope areas had the highest species diversity (0.94 for the control and 0.84 for the nitrogen-treated), and the Upper Basin Slope area, shrub vegetation zone, had the lowest species diversity (0.27 for the control and 0.05 for the nitrogen-treated) in both transects. Inorganic nitrogen in the nitrogen-treated transect soils was consistently higher than that in the control transect soils; however, the former showed more fluctuation from station to station in the latter. Above-ground biomass of spring annual plants in the nitrogen-treated transect was consistently higher than that in the control at each station. The maximum above-ground biomass in the control and nitrogen-treated transect was 24.4+-4.4 g m-2 and 61.2+-10.6 g m-2, respectively. Variations in above-ground biomass along the transect did not parallel with the variation in inorganic nitrogen in soils and species diversity.ty.

}, keywords = {annual plants,nitrogen amendment, article, articles, dominance-diversity curve, ecosystem dynamics, annual plants, fertilization, nitrogen, journal, journals, nitrogen amendment, plants, annual distribution, plants, primary production, plants, response to nitrogen, plants, species diversity, primary production, annual plants, species diversity, transect,annual plants}, url = {files/bibliography/JRN00094.pdf}, author = {Hyeong-Tae Mun and Walter G. Whitford} } @mastersthesis {51687, title = {The effects of microarthropods on nitrogen availability within the rhizosphere of Erioneuron pulchellum in a northern Chihuahuan Desert ecosystem}, year = {1989}, note = {//NMSU//NONE, LTER//}, month = {1989}, pages = {127}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {Recent studies suggest that rhizosphere soil microarthropods may have a major role in determining soil nitrogen availability. Desert soil microarthropods are consumers of soil bacteria, fungi, and nematodes, thus they accelerate mineralization processes by causing turnover in immobilized nitrogen. Therefore, I hypothesized that changing densities of soil microarthropods would result in changes in nitrogen availability.... These data suggest that in the live rhizosphere of Erioneuron pulchellum, if water is available, then soil biota and nitrogen dynamics might be regulated by organic matter. Also, there were no significant differences in nitrogen mineralization potentials of soils from the various treatments. These data indicate that soil microarthropods are not essential for nitrogen mineralization or other aspects of the nitrogen cycle in the rhizosphere of fluff grass.}, keywords = {dissertation, dissertations, Erioneuron,microarthropods, Erioneuron,nitrogen availability, grass,Erioneuron, grass,fluff grass, microarthropod,nitrogen availability, nematode, pesticide, Chlordane, rhizosphere,Erioneuron, simulated rainfall,Erioneuron, soil, nitrogen availability, theses, thesis}, author = {Solange Silva} } @article {51698, title = {Effects of organic amendments on soil biota on a degraded rangeland}, journal = {Journal of Range Management}, volume = {42}, number = {1}, year = {1989}, note = {//OTHER//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {56-60}, abstract = {

Rehabilitation of degraded rangeland requires rebuilding the soil, including soil biota. In this study wheat straw, bark and wood chips, and dried municipal sludge were placed on native range plots in northcentral New Mexico. Organic amendments had little or no effects of decomposition of straw, litter respiration, soil respiration, biomass of soil microflora, and populations of most of the soil biota in the second year of the study. The differences in soil nematode and microarthropod population densities and straw decomposition occurred only in the bark and wood chip mulched plots in year 1. The absence of differences in year 2 may have been the result of below-average rainfall. The wood chip bark mulch was visibly present at the end of year 2 but the other mulches were not. There may be long-term benefits from application of recalcitrant mulches like wood chips and bark, but the less recalcitrant mulching like straw and low application rates of sludge produce no measurable benefit.

}, keywords = {article, articles, journal, journals, microarthropod,nutrients, nematode,organic amendment, organic amendments, rangeland, microarthropods, soil biota,organic amendments}, doi = {10.2307/3899659 }, url = {files/bibliography/JRN00095.pdf}, author = {Walter G. Whitford and Earl F. Aldon and D. W. Freckman and Yosef Steinberger and L. W. Parker} } @article {51699, title = {Effects of water and nitrogen supplementation on phenology, plant size, tissue nitrogen, and seed yield of Chihuahuan Desert annual plants}, journal = {The Southwestern Naturalist}, volume = {34}, number = {4}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {546-549}, abstract = {

We measured nitrogen content of plant parts, seed yield, and plant mass of four species of spring annual plants grown under different water and soil nitrogen conditions. We hypothesized that nitrogen would have little effect or a detrimental effect of the nitrogen-fixing legume A. nuttallianus. We hypothesized that water would have the greatest effect of the species of annuals that exhibit little or no growth response to soil nitrogen availability (E. diffusum and E. nuttallianus). Plant tissue nitrogen and seed production were hypothesized to increase in the nitrogen fertilizer-responsive species. L. lasiocarpum and C. stevioides.

}, keywords = {annual plant, biomass, annual plant, nutrient amendment, annual plant, phenology, annual plant, seed yield, annual plant,rainfall simulation, annual plants, biochemistry, article, articles, journal, journals, nitrogen,annual plants, phenology,annual plants, rainfall simulation, annual plants, seed yield,annual plants}, doi = {10.2307/3671516 }, url = {files/bibliography/JRN00096.pdf}, author = {Walter G. Whitford and Julio R. Gutierrez} } @conference {51715, title = {The effect of precipitation patterns on the phenology of Sprobolus flexuosus}, booktitle = {41st Annual Meeting, Society for Range Management}, year = {1988}, month = {1988}, pages = {209}, author = {Gibbens, Robert P.} } @article {51717, title = {Effects of different patterns of supplemental water and nitrogen fertilization on productivity and composition of Chihuahuan Desert annual plants}, journal = {The American Midland Naturalist}, volume = {119}, number = {2}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {336-343}, abstract = {

The effects of supplemental water supplied as large events, 25 mm per month, or as frequent small events, 6 mm per week, and available nitrogen on density, aboveground biomass and species composition of an annual plant community were studied in the northern Chihuahuan Desert. The amendments of water an N had no effect on total annual plant density. However, supplemental water resulted in increased density of eight species and nitrogen fertilization produced increased densities in nine species. Total aboveground biomass was higher in the nitrogen fertilized plots; water amendments had no effect on dry matter production and there were no significant water-nitrogen interactions. Cluster analysis showed that species composition was similar on the fertilized plots and that the plots receiving 25 mm month-1 additional water in a single event differed most from the others. Species richness was highest in the 6 mm week-2 , unfertilized plots, and lowest in the unwatered-unfertilized plots. Biomass production of six of the 23 species recorded was significantly increased by nitrogen fertilization and biomass of two species was significantly reduced.

}, keywords = {annual plant, density, annual plant,aboveground biomass, annual plant,nitrogen amendment, annual plant,species composition, annual plant,water amendment, article, articles, journal, journals, nitrogen, amendment, plant, productivity, productivity,annual plants, rainfall simulation}, doi = {10.2307/2425816 }, url = {files/bibliography/JRN00076.pdf}, author = {Julio R. Gutierrez and Da Silva, Oswaldo A. and Maria I. Pagani and Danforth Weems and Walter G. Whitford} } @article {51723, title = {Effects of breeding season, nutritional environment and lambing management on lamb production of Southwest Rambouillet ewes}, journal = {Theriogenology}, volume = {29}, number = {6}, year = {1988}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1988. (http://www.sciencedirect.com/science/journal/0093691X)}, month = {June 1, 1988}, pages = {1295-1302}, abstract = {

Effects of season, nutritional environment and lambing management were studied on the numbers and weights of lambs produced in fine-wool sheep in southwestern New Mexico over a 2-yr period. One group of ewes was maintained and lambed on arid range (range-range). A second group was maintained on range except during lambing and early lactation (range-pasture). The third group was maintained on irrigated pasture (pasture-pasture). Groups 2 and 3 were lambed together on irrigated pasture or in drylot, depending on the season, and maintained as one group on pasture until the lambs averaged 60 d of age. At about 60 d of age, all lambs were weaned and fed in the drylot as one group. Fall lamb production was much lower (P\<0.001) than at other seasons of the year. Changing the breeding time for the fall lambing from April to mid May greatly improved lamb production. The primary problems with fall lambing appeared to be a lower percentage of ewes showing estrus and a lower twinning rate. Lamb production based on birth and survival rate and weaning weights of ewes lambing on range was markedly lower to lamb production of range-managed ewes lambing in drylot or on pasture (P\<0.001). The difference was primarily due to low lamb survival on the range. The causes of loss appear to be predation, deficient mothering ability and exposure. Lambing season had no real effect on wool production, but pasture-managed ewes produced 0.4 kg more grease wool than ewes kept continuously on the range (P\<0.05). Lamb production can be improved by lambing ewes in drylot or on pasture, by avoiding lambing during coldest months, and by providing shelter from cold and wind the first 3 d of life.

}, keywords = {breeding season, lamb production, lambing management, nutrition, rangesheep}, doi = {10.1016/0093-691X(88)90009-X}, url = {/files/bibliography/335.pdf}, author = {Clarence V. Hulet and Shupe, W. Larry and L. W. Murray} } @article {51726, title = {Estimating digestibility and faecal output in lambs using internal and external markers}, journal = {Journal Agricultural Science}, volume = {111}, year = {1988}, month = {1988}, pages = {19-25}, address = {Great Britain}, keywords = {digestibility, lambs}, url = {/files/bibliography/88-001.pdf}, author = {Krysl, L.J. and Galyean, M.L. and Richard E. Estell and Sowell, B.F.} } @article {51730, title = {The effect of CaCO3 on the uptake of phosphorous by two desert shrub species Larrea tridentata (D. C.) Cov. and Parthenium incanum H.B.K.}, journal = {Botany Gazette}, volume = {149}, number = {3}, year = {1988}, note = {//NMSU//NONE, LTER//}, month = {1988}, pages = {328-334}, abstract = {In a phytotron growth study, the effects of soil CaCO3 on the uptake of P by two desert shrub species were species specific. Larrea tridentata seedlings responded to soil CaCO3 with increased root:shoot ratios, increased N:P ratios in tissues, and decreased specific absorption rates of P, indicating that CaCO3 directly inhibited the uptake or the availability of P to roots. Parthenium incanum seedlings responded negatively to CaCO3, but this response was not specific to P uptake and did not appear to be caused by a reduction in P availability. Pedogenic carbonates, present in many arid-land soils of the world, might greatly affect both P availability and the biogeochemical cycle of P in desert ecosystems.}, keywords = {article, articles, calcium carbonate, germination, Larrea, journal, journals, Larrea, phosphorous, nutrient cycling, phosphorous, Larrea, Parthenium, phosphorous, phosphorous, seed, also SEE germination}, author = {Kate Lajtha and W. H. Schlesinger} } @article {51727, title = {The effect of varying nitrogen and phosphorus availability on nutrient use by Larrea tridentata, a desert evergreen shrub}, journal = {Oecologia}, volume = {75}, year = {1988}, note = {//NMSU//NONE, LTER//}, month = {1988}, pages = {348-353}, abstract = {In a phytotron study of the effects of nitrogen and phosphorus supply ration on nutrient uptake and use by Larrea tridentata, seedlings responded to increases in N and P availability with increases in leaf size, total biomass, and leaf nutrient concentration, and with decreases in root:shoot ratio. N and P use efficiency decreased with increasing N and P availability, respectively, but increased with increasing availability of the other nutrient, suggesting that Larrea responds both to the absolute and to the relative availability of limiting nutrients. Absolute amounts of N and P resorption, as well as N and P resorption efficiencies did not demonstrate a significant trend with nutrient availability, and there was no evidence of significant interactions between the two nutrients. More studies of the effects of nutrient interactions in the cycling and use of nutrients by different plant species are needed before more general conclusions can be drawn.}, keywords = {article, articles, journal, journals, Larrea, germination, nitrogen, Larrea, germination, phosphorus, Larrea, nutrients, nitrogen, Larrea, nutrient resorption efficiency, nutrient use efficiency, phosphorus, Larrea, seed, germination}, author = {Kate Lajtha and Klein, Melanie} } @book {51734, title = {Ecology of small desert playas}, series = {Small Water Impoundments in Semi-arid Regions}, year = {1988}, note = {//NMSU//LTER I//ProCite field[6]: In}, month = {1988}, pages = {89-113}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {Data from a playa located in New Mexico were compared to earlier data and those from other playas to identify the effects of flooding. Tests of hydrology and chemistry showed the following: water loss to percolation and evaporation; potassium concentrations were higher than those for sodium; and neither the playa water nor soil had a significant increase in chemical compounds from the drainage area following flooding.}, keywords = {amphibian, playa, book, books, chapter, chapters, ecology, playa, invertebrate, playa, nutrient cycling, playa, playa, amphibians, playa, food web, playa, invertebrates, playa, life cycle, playa, nutrient cycling, report, reports, transect, amphibians, transect, invertebrates, transect, nutrient cycling, transect, playa}, isbn = {0826310532; ISBN-13: 9780826310538}, author = {S. J. Loring and William P. MacKay and Walter G. Whitford}, editor = {Thames, J. L. and Ziebell, C. D. (eds.)} } @article {51738, title = {An English-Spanish glossary of terminology used in forestry, range, wildlife, fishery, soils and botany}, year = {1988}, note = {//OTHER//NONE//}, month = {1988}, institution = {USDA Forest Service}, address = {Fort Collins, Colorado}, abstract = {The purpose of this glossary is to present to translators, scientists, resource managers, administrators and others the Spanish-English equivalent translations of scientific management terms commonly used in the disciplines of forestry, range management, wildlife management, fisheries, soils and botany.}, keywords = {bilingual glossary, book, books, chapter, chapters, English-Spanish glossary, glossary, bilingual, report, reports, terminology,bilingual glossary}, isbn = {General Technical Report RM-152}, author = {A. Medina} } @mastersthesis {51743, title = {Effect of protein supplementation on performance, water intake and travel of beef cattle grazing semidesert rangeland in South-central New Mexico}, year = {1988}, note = {//NMSU//NONE//}, month = {1988}, pages = {136}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, N.M.}, abstract = {Trials were conducted in 1986 to study the effect of supplementing cows with 41\% crude protein (CP) cottonseed pellets on their subsequent liveweight change, calf liveweight change, fecal botanical composition, daily water consumption and travel in cows grazing semidesert rangeland between 16 April and 18 August. Effects of physiological status (lactating vs. non-lactating) were also considered.}, keywords = {cattle grazing,behavior, cattle,behavior, cattle,protein supplementation, cattle,water intake, dissertation, dissertations, grazing management, theses, thesis}, author = {R. R. Rouda} } @article {51751, title = {Effects of harvester ant (Pogonomyrmex rugosus) nests on soils and a spring annual, Erodium texanum}, journal = {The Southwestern Naturalist}, volume = {33}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {482-485}, abstract = {

Based on the observations of Erodium texanum and the literature, I hypothesized that the density and biomass of E. texanum would be higher around the nest discs of Pogonomyrmex rugosus because of higher soil nutrient levels. Elevated soil nutrients at the edges of mounds of seed harvesting ants have been described in other areas.

}, keywords = {ant nest, Erodium, ant nest, soil effects, ant nests,nutrients, ant, harvester,Pogonomyrmex, article, articles, Erodium,ant nest effects, insect, also SEE , journal, journals, nutrients,ant nests, Pogonomyrmex,soil effects, soil properties, ant nests}, doi = {10.2307/3672218 }, url = {files/bibliography/JRN00077.pdf}, author = {Walter G. Whitford} } @article {51748, title = {Effects of rainfall supplementation on microarthropods on decomposing roots in the Chihuahuan Desert}, journal = {Pedobiologia}, volume = {31}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {147-155}, abstract = {

As part of a study designed to test the hypothesis that single large quantity rainfall events would result in higher rates of root decomposition than small frequent rainfall events or no supplemental water, we sampled the microarthropods associated with the decomposing roots. We hypothesized that supplemental water would not only affect the rates of decomposition but would also affect the species composition and biomass of the micrfauna feeding on the microflora on the roots. We further hypothesized that the successional trends in microarthropod populations observed on buried litter by Santos and Whitford (1981) would be similar on decomposing roots.

}, keywords = {article, articles, decomposition, microarthropods, decomposition,roots, journal, journals, microarthropod,decomposition, microarthropod,rainfall simulation, rainfall simulation, microarthropods, rainfall simulation,decomposition, root,decomposition}, doi = {10.1007/BF00378764}, url = {files/bibliography/JRN00078.pdf}, author = {Walter G. Whitford and Stinnet, K. and Yosef Steinberger} } @conference {51757, title = {Effectiveness of cattle in protecting lambs from coyote predation}, booktitle = {40th Annual Meeting, Society for Range Management}, year = {1987}, month = {1987}, pages = {2}, author = {D.M. Anderson and Clarence V. Hulet and J. N. Smith and Shupe, W. Larry} } @article {51762, title = {The effects of chromosome number on sex expression in Atriplex canescens}, journal = {Botanical Gazette}, volume = {148}, number = {3}, year = {1987}, month = {September 1987}, pages = {379-385}, abstract = {

Native diploid, tetraploid, and hexaploid populations of Atriplex canescens were surveyed in southern New Mexico and west Texas. Female to male ratios were approximately equal in diploid populations and female-biased in tetraploid and hexaploid populations. Tetraploids in New Mexico and Texas differed from northern populations with more male and fewer monoecious plants. Hexaploids appeared to have slightly fewer female plants than tetraploids during flowering, but during the winter there were 6\%-20\% more seed-bearing plants because of the high frequency of monoecious plants. The three cytotype populations generally fited expected ratios using an X, Y sex-determining model. Monoecious diploid plants cannot be explained by the genetic model. Two types of monoecious expressions were observed, and possible genetic mechanisms are discussed.

}, url = {/files/bibliography/310.pdf}, author = {J.R. Barrow} } @mastersthesis {51766, title = {Effects of harvest ants, Pogonomyrmex rugosis, nest on soil properties and vegetation in the Chihuahuan Desert}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1987}, pages = {49}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Cover and density of winter annual plants on the perimeters of ant nests were compared with those of adjacent reference sites in three habitats at Jornada LTER, New Mexico, USA. There was a distinct floristic assemblage of winter annual plants on ant nest perimeter in comparison to reference sites. Descurainia pinnnata, Lesquerella gordonii, Malacothrix fendleri, and Eriogonum abertianum were strongly associated with ant nest perimeters and had higher cover on ant nest perimeters. The floristic assemblages and cover were least affected by presence of harvester ant nests in the grama grassland habitat and most affected on the basin slope mixed habitat. Soil chemical analyses did not show large generalized differences in nutrient contents. However, there were higher concentrations of NO3-N and inorganic P on ant nest perimeters and also, there were different ratios of resources (e.g., water, and N and P availability) due to ant soil disturbance on ant nest perimeter. Floristic assemblage could be determined by a fortuitous juxtaposition of clumped seeds at beginning of winter, by intra and interspecific competition of winter annual during February and March, and mediated by ant clipping at the end of April and May. There was no significant differences in below ground biomass between ant nest perimeter and reference sites. This may be due to intense clipping of annual plants by ants on nest perimeters in April.}, keywords = {annual plant, ant nests, ant nest, nutrients, ant nest, soil properties, ant nest, vegetation, ant, harvester, ant, Pogonomyrex, ant, Pogonomyrmex, dissertation, dissertations, nitrogen, nutrients, ant nests, phosphorus, Pogonomyrex, vegetation, Pogonomyrmex, soil properties, soil, ant nest, theses, thesis}, author = {Di Marco, Rudolfo Ruben} } @article {JRN54830, title = {Effects of Cattle Grazing Upon Chemical Constituents Within lmportant Forages for Elk}, journal = {Northwest Science}, volume = {61}, year = {1987}, month = {1987}, pages = {70-73}, chapter = {70}, abstract = {

On many western rangelands, cattle and elk use the same forages but during different seasons. This can place these species into indirect competition or amensalism. The objective of this study was to examine the effects of summer grazing by cattle upon the winter forage quality for elk. Individual plants of bluebunch wheat glass (Agropyron spicatum), rough fescue (Festuca scabrella), and ldaho fescue (Festuca idahoensis) were monitored for phenological stage when summer grazed by cattle on a Rocky Mountain elk (Cervus elaphus nelsoni) wintering range in the Elkhorn Mountains, Montana. \ Assessment of winter chemical composition of these three key forage species indicated no deleterious effects of summer grazing by cattle stocked at 3.7 ha/AUM upon the winter forage quality. In general, rough fescue and ldaho fescue had lower average fiber fractions and higher crude protein than bluebunch wheatgrass. Under deferred rotation cattle management, the primary winter elk forage management concern appears to be forage quantity rather than quality.

}, keywords = {cattle grazing, Chemical Constituents, effects, Elk, forages}, url = {https://research.wsulibs.wsu.edu/xmlui/bitstream/handle/2376/1754/v61\%20p70\%20Dragt\%20and\%20Havstad.PDF?sequence=1}, author = {J. W Dragt and Kris Havstad} } @article {51769, title = {Effect of irrigation on nematode population dynamics and activity in desert soils}, journal = {Biology and Fertility of Soils}, volume = {3}, year = {1987}, note = {//NMSU//LTER I//}, month = {1987}, pages = {3-10}, abstract = {

The nematode community in litter and soil was examined for a year in the Chihuahuan desert, before and after supplemental rainfall application. Proportions of nematode-active or anhydrobiotic forms and population densities were determined for 3 treatments: control (natural rainfall), a single, large (25-mm) monthly irrigation pulse, and 4 smaller (6-mm) irrigations spaced at weekly intervals. In litter the greatest nematode abundance was in the 6 mm week-1 treatment (48 nematodes 20 g-1 litter). Bacteriovores and fungivores accounted for approximately 95\% of the numbers and biomass in all treatments. In soil, water amendments had no significant effect (P\<0.05) on annual mean densities of total nematodes, fungivores, bacterivores, or omnivore predators. Phytophage densities were greater on both irrigation treatments, with highest densities (9298 m-2) in the 6 mm week-1 soils, which was 5,9\% of the total soil nematode density. Total densities of individual trophic groups were not significantly different before or after rainfall. soil nematode densities fluctuated independently with trophic group, month, and season. Bacterial feeders and omnivore predators were the largest contributor to total nematode density and biomass. Prior to irrigation, there were no differences in the percentage of anhydrobiotes on the three treatments. Anhydrobiotes decreased after irrigation in all treatments, and were significantly lower in soils of the larger, monthly irrigation. Nematodes were inactive (anhydrobiotic) and decoupled from decomposition processes when soil water matric potentials reached -0.4 MPa.

}, keywords = {article, articles, irrigation,SEE , journal, journals, nematode community, nematode, rainfall simulation, nematode,anhydrobiosis, rainfall simulation,nematode population}, doi = {10.1007/BF00260571}, url = {files/bibliography/JRN00054.pdf}, author = {D. W. Freckman and Walter G. Whitford and Yosef Steinberger} } @article {51787, title = {The effects of nitrogen, water and sulfur amendments on surface litter decomposition in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {12}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1987}, pages = {223-232}, abstract = {

The effects of nitrogen, water and sulfur amendments on the decomposition rates of three types of surface litter in the northern Chihuahuan Desert were evaluated. The amendments had no effects on the decomposition rates of leaf litter from black grama (Bouteloua eriopoda) and creosotebush (Larrea tridentata). The rate of fluff grass (Erioneuron pulchellum) litter decomposition was increased by water and decreased by sulfur. Water affected fluff grass decomposition by increasing terminate (Gnathamitermes tubiformans) above-ground activity. Sulfur decreased termite activity. These data suggest that the decomposer microflora and microfauna of the northern Chihuahuan Desert are more limited by quantity of organic matter than by water and nitrogen. Hence they do not respond opportunistically to increased availability of such resources.

}, keywords = {article, articles, Bouteloua, decomposition, litter, decomposition, nutrient effects, Erioneuron, Gnathamitermes, journal, journals, Larrea, litter decomposition, nitrogen amendment, sulfur amendment, termites, water amendment}, doi = {10.1016/S0140-1963(18)31166-2}, url = {files/bibliography/JRN00062.pdf}, author = {William P. MacKay and F. M. Fisher and Solange Silva and Walter G. Whitford} } @conference {51809, title = {Effect of livestock exclusion on grass basal cover and shrub canopy cover on southern New Mexico mesa dropseed ranges}, booktitle = {39th Annual Meeting, Society for Range Management}, year = {1986}, month = {1986}, pages = {111}, keywords = {basal cover, dropseed ranges, exclusion, grass, livestock, shrub canopy}, author = {T.L. Atwood and Gibbens, Robert P. and Reldon F. Beck} } @article {51810, title = {Estimation of the Philip infiltration parameters from rainfall simulation data}, journal = {Soil Science Society of America Journal}, volume = {50}, year = {1986}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1986}, pages = {1319-1323}, abstract = {

A new, simple technique for estimating the parameters of the two-term Philip infiltration equation was developed and tested using field-measured data obtained in the northern Chihuahuan desert of New Mexico. The technique simultaneously provided information on the relationship between the Philip equation parameter A, and the field-measured hydraulic conductivity. The equation was reformulated as I - cKf = 1/2St-1/2, where I is the infiltration rate, S the sorptivity, t the time, Kf the field-measured final infiltration rate, and c, a coefficient relating Kf to the Philip parameter A. The final, steady infiltration rate measured in the field was used for the value of Kf. Regressions of (I - cKf) vs. (1/2t-1/2) for values of c between 0 to 1 resulted in optimum values for each treatment along with their corresponding S values. For the soils in this area, values for the coefficient c were somethimes outside the suggested range of 0.33 to 0.67, and were different for each study site. The regression analysis also showed that the value of S can be highly sensitive to changes in c. Using the values of S and c determined by the proposed method, a comparison was made between computed infiltration rates and measured infiltration rates. The results of this study showed that the prediction method provided adequate fits to field-measured data, and that the choice of an appropriate c factor is important in determining infiltration parameters from field data.

}, keywords = {article, articles, hydrology,infiltration prediction, infiltration, rate, journal, journals, rainfall simulation, runoff}, url = {files/bibliography/JRN00035.pdf}, author = {Bach, L. B. and Peter J. Wierenga and Timothy J. Ward} } @article {51836, title = {Effects of nutritional environment and ram effect on breeding season in range sheep}, journal = {Theriogenology}, volume = {25}, number = {2}, year = {1986}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1986. (http://www.sciencedirect.com/science/journal/0093691X)}, month = {February 1, 1986}, pages = {317-323}, abstract = {Effects of season, nutritional environment, and presence of rams on incidence and rate of ovulation in fine-wool sheep in southern New Mexico were investigated over 14 months (February 1983{\textendash}March 1984). Number of corpora lutea (CL) were observed each month by laparoscopy in random samples from six ewes in each subgroup. Seasonality of ovulation in fine-wool sheep managed on range was much more marked than in animals managed on alfalfa hay in drylot. Incidence of ovulation approached zero in range-managed ewes during May, June, and July (8\%, 0\%, 4\%) but was higher (P<0.05) in the alfalfa-drylot group (42\%, 17\%, 75\%), respectively. Although the incidence remained lower (P<0.05) in August in range-managed than in drylot ewes (50\% and 83\%, respectively), both groups were ovulating at a high rate during September through January. Incidence of ovulation dropped dramatically both years in the range-managed group in February compared with that of the alfalfa-drylot group (48\% and 36\% vs 100\% and 83\%). Mean ovulation rate per ewe ovulating did not differ (P>0.10) between nutrition groups within the 14 months. Body weight was related to CL number during periods of seasonal transition only. Continuous or intermittent presence of a ram had no real effect on either incidence or rate of ovulation during the transitional months. Nutritional environment can affect seasonality of breeding in fine-wool range sheep. This effect may not be consistently modified by presence of rams.}, keywords = {breeding season, nutrition, ovulation, ram effect, range sheep}, url = {/files/bibliography/300.pdf}, author = {Clarence V. Hulet and Shupe, W. Larry and Ross, T.T. and Richards, W.A.} } @article {51842, title = {Effect of increased soil moisture and reduced soil temperature on a desert soil arthropod community}, journal = {The American Midland Naturalist}, volume = {116}, number = {1}, year = {1986}, note = {//NMSU//LTER I//}, month = {1986}, pages = {45-56}, abstract = {

The effects of soil moisture and temperature on arthropod communities were experimentally examined in the northern Chihuahuan Desert of New Mexico. Shaded plots were established which lowered the soil temperature several degrees; some plots received artificial rainfall to increase soil moisture. Shading reduced soil temperature at 5-cm depth 7-10 C. Soil moisture at 5 cm accounted for most of the variation in surface activity of subterranean termites (r values between 0.3 and 0.7). Termites did not respond to temperature differences. When all soils were at field capacity, there was no difference in termite activity in shaded and unshaded plots. There were higher densities of microarthropods in litter bags on the shaded plots than on the unshaded plots. Numbers of microarthropods were an order of magnitude larger in litter bags on watered and shaded plots than on other plots. Lower litter temperatures apparently affect litter arthropods more than increased soil moisture. Shade had no effect on ant colonies but there were fewer colonies on the watered plots. There was between 40 and 59\% mass loss from creosotebush leaf litter after 7 months on all plots. Water and soil temperature had no effect on decomposition rates.

}, keywords = {ant colonies, shading, ant colonies, soil moisture, article, articles, decomposition, rates of, decomposition, surface litter, termite, journal, journals, microarthropod, decomposition rate, microarthropod, densities, microarthropod, soil moisture, microarthropod, temperature, simulated rainfall, soil moisture,arthropod, soil temperature,arthropod, termite, activity, termite, decomposition, termite, surface litter}, doi = {10.2307/2425936 }, url = {files/bibliography/JRN00034.pdf}, author = {William P. MacKay and Solange Silva and David C. Lightfoot and Maria I. Pagani and Walter G. Whitford} } @mastersthesis {51849, title = {The ecology and evolutionary implications of competition and parthenogenesis in Cnemidophorus}, year = {1986}, note = {//LOCAL//NONE//}, month = {1986}, pages = {171}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {This study reports the results of a manipulation experiment conducted over a 5-year period in southcentral New Mexico designed to test the common hypothesis of ecological competitiveness of parthenogenetic Cnemidophorus.... The explanation for the demonstrated failure of Cnemidophorus tesselatus to respond to the experimental manipulation reported here may be more fundamentally related to its genetic character than to its ecological position relative to C. tigris.}, keywords = {Cnemidophorous, parthenogenesis, Cnemidophorous,competition, competition,lizards, dissertation, dissertations, lizard,Cnemidophorous, lizard,competition, lizard,parthenogenesis, reptilia, SEE , theses, thesis}, author = {Price, Andrew Hoyt} } @booklet {51854, title = {Effects of UV-B Radiation on Photosynthesis}, volume = {NATO Advanced Science Institute Series, Ecological Science. Stratospheric Ozone Reduction, Solar Ultraviolet Radiation and Plant}, year = {1986}, month = {1986}, pages = {376 pp}, publisher = {Springer-Verlag}, address = {Berlin, Germany}, abstract = {

Several component reactions of photosynthesis, and net C02 assimilation rates have been shown to be detrimentally affected by UV-B radiation levels equal to or above those presently received at various locations on the earth{\textquoteright}s surface. Many of these studies, however, were completed under environmental conditions that deviated from ambient field conditions to such an extent that extrapolation of results for predictive purposes would probably overestimate the harmful effects of reduced atmospheric ozone levels and the concomitant increases in UV-B radiation. Nevertheless, the photosynthetic process has been shown to be sensitive to UV-B radiation and, therefore, warrants further study. The ability of plants to tolerate increased levels of UV-B radiation, relative to photosynthetic capacity, may be dictated by acclimation processes that would intensify UV-B attenuation prior to its absorbance by sensitive components or reactants of photosynthesis

}, url = {/files/bibliography/302.pdf}, author = {Sisson, W.B.}, editor = {Worrest, R.C. and Caldwell, M. M.} } @mastersthesis {51886, title = {An evaluation of a change-in-ratio estimate of coyote abundance on the Jornada Experimental Range}, year = {1985}, note = {//USDA//NONE//}, month = {1985}, pages = {65}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {coyote, abundance, dissertation, dissertations, mammal, coyote, abundance, theses, thesis}, author = {Kumm, James E.} } @article {51892, title = {Effects of oxamyl and chlordane on the activities of nontarget soil organisms}, journal = {Biology and Fertility of Soils}, volume = {1}, year = {1985}, note = {//NMSU//NONE, LTER//}, month = {1985}, pages = {141-148}, abstract = {

The effect of two pesticides, oxamyl and chlordane, on nontarget soil biota were examined in microcosms. Neither oxamyl nor chlordane had an effect on rates of litter decomposition or soil and litter respiration. There were differences in numbers of nematodes and protozoans and in biomass of bacteria and fungi in microcosms with and without chlordane on some sampling dates. One of the nematodes, Pelodera sp., died out in all of the microcosms within 30 days. Although the pesticide chlordane had no measurable effect on the activities of the soil biota as measured by respiration and mass loss, it did affect the population sizes and biomass of some grazers of soil biota.

}, keywords = {article, articles, journal, journals, microcosms, microflora, nematodes, pesticide, Chlordane, pesticide, Oxamyl, soil nitrogen, soil organism, SEE , soil organisms,pesticide effects, soil-litter respiration}, url = {files/bibliography/JRN00021.pdf}, author = {L. W. Parker and J. Ryder-White and S. Thomas and Walter G. Whitford} } @mastersthesis {51907, title = {Ephemeral plant responses to termites, water and nitrogen in a Chihuahuan Desert}, year = {1984}, note = {//NMSU//NONE, LTER//}, month = {1984}, pages = {102}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {The effects of subterranean termites, water supplementation and nitrogen amendment on ephemeral plant biomass, cover and density were investigated in a Chihuahuan desert ecosystem. Plants were sampled on one plot of 1200 m2 previously treated with chlordane to eliminate the termites and one untreated plot (with termites). These plots were subdivided in twelve 3 x 3 m subplots. Six of these subplots were irrigated every 15 days with 13 mm H2O and the other six received only natural rainfall (unwatered plots). Three randomly selected plots in the watered and unwatered treatments in both termite and no termite plots were fertilized with 2.5 g/m2 ammonium nitrate. Soil temperature and soil moisture in the watered and unwatered plots were measured on a regular basis. Soil nitrogen and tissue nitrogen of some selected plant species growing in the different treatments were analyzed. There were no differences in soil temperature among treatments. Soil moisture was higher in the termite than in the no-termite plots, and in the watered than in the unwatered plots during spring and summer. Soil nitrogen was higher in the no-termite than in the termite plot. Long-lived plant species such as Baileya multiradiata and Eriastrum diffusum accumulated more nitrogen in the termite and watered plots than in the no-termite and unwatered plots. Short-lived species did not exhibit differences in tissue nitrogen when the different treatments were compared. Ephemeral plant species composition differed, but neither total plant biomass nor total plant cover differed between termite and no-termite plots. Most of the species responded to the water treatments either by lengthening their growing seasons, increasing their density or increasing their biomass production. In most of the cases water amendments had a greater effect on the species abundances in the no-termite than in termite plots. In the termite plots, nitrogen amendments produced the larger effects and plant response to the treatments suggests that, in the no-termite plots, the system is shifting from one dominated by water-responsive species to another dominated by nitrogen-responsive species. Termite plots were dominated by deep-rooted water-responsive species (e.g., B. multiradiata).}, keywords = {dissertation, dissertations, ephemeral plant, also SEE , ephemeral plant, nutrients, ephemeral plant, termites, nitrogen, amendment, pesticide, Chlordane, rainfall simulation, ephemeral plants, termite, Chlordane, termite,plant response, theses, thesis, water, amendment}, author = {Julio R. Gutierrez} } @article {51908, title = {The effect of shade and planting depth on the emergence of fourwing saltbush}, journal = {Journal of Range Management}, volume = {37}, number = {1}, year = {1984}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {January 1, 1984}, pages = {22-24}, abstract = {

Planting trials in southern New Mexico with fourwing saltbush seeds on mesquite dunes and on shaded and nonshaded interdune areas during 3 successive years revealed that seedling emergence was always greater on shaded areas. Planting depth (2 and 5 cm) did not appear to be a critical factor in seedling emergence. The shade provided by mesquite canopy explains, in part, why fourwing saltbush occurs with much higher frequency on dunes than on interdune areas.

}, doi = {10.2307/3898816}, url = {/files/bibliography/258.pdf}, author = {J.T. Hennessy and Gibbens, Robert P. and J.M. Tromble and Manual Cardenas} } @article {51909, title = {Early weaning and part-year confinement of cattle on arid rangelands of the Southwest}, journal = {Journal of Range Management}, volume = {37}, number = {2}, year = {1984}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {March 1, 1984}, pages = {127-130}, abstract = {

This study compared part-year confinement of cows with yearlong placement on rangeland and weaning calves in late May with regular weaning in mid-October. Weaning rates tended to be higher with part year confinement than with yearlong placement on rangeland (86\% vs. 72\%) and with early weaning in May than with regular weaning in October (86\% vs. 72\%). There were significant year effects in weaning weights with the lowest weights in drought years. The production per cow exposed tended to be higher with part-year confinement than with yearlong placement on rangeland (134 kg vs. 110 kg), and with regular weaning than with early weaning of calves (156 kg vs. 88 kg). Part-year confinement of cows and early weaning of calves are useful tools for the range manager in droughty years.

}, url = {/files/bibliography/261.pdf}, author = {C.H. Herbel and Wallace, J.D. and Finkner, M.D. and Yarbrough, C.C.} } @conference {51913, title = {Effects of nutritional environment on breeding season in range sheep}, booktitle = {Journal of Animal Science}, volume = {59(Suppl 1)}, year = {1984}, month = {1984}, pages = {339}, abstract = {

The objectives were to determine effects of the season, nutritional environment, and presence of the ram on incidence and rate of ovulation in finewool sheep in southern New Mexico. Mature ewes (144 head) were randomized into groups maintained either on arid Southwest range or in drylot on alfalfa hay (1.59 kg/head/day). These nutrition-environment groups were further randomized into ram-exposure subgroups to test effects of continuous or intermittent exposure (30-day periods) to sterile rams. Both drylot and range-managed ewes were in good condition and gained weight during the study (9.8 and 5.1 kg/ewe). Copora lutea were observed twice each month for 13 months in random samples of three to six ewes from each subgroup. Seasonality of ovulation in finewool sheep managed on the range was much more marked than in animals managed on alfalfa hay in drylot. The incidence of ovulation approached zero in the range-managed ewes during May, June, and July (8\%, 0\%, and 4\%, respectively), compared with 42\%, 17\% and 75\% for the alfalfa-drylot group (P\<.02, P\<.10, P\<.01). Although the incidence of ovulation in the range-managed group increased to 50\% in August, the incidence was still lower (P\<.05) than in the drylot-hay group (83\%). The incidence of ovulation also was lower (P\<.01) in the range-managed than the drylot ewes during February (33\% vs. 83\%). Ovulation rate was highest in October (1.66) and November (1.63) and lowest in March (1.14) and May (1.14). The mean annual ovulation rate of the drylot group (1.48) was very similar (P\>.10) to that of the range-managed group (1.39). Continuous or intermittent presence of a ram had no real effect on either the incidence or rate of ovulation. It is concluded that the nutritional environment can significantly affect seasonality of breeding in finewool range sheep. This may not be consistently modified by ram exposure.

}, keywords = {breeding season, nutrition, ovulation rate, range sheep}, url = {/files/bibliography/268.pdf}, author = {Clarence V. Hulet and Shupe, W. Larry and Ross, T.T.} } @article {51921, title = {Effects of simulated rainfall and litter quantities on desert soil biota: soil respiration, microflora and protozoa}, journal = {Pedobiologia}, volume = {27}, year = {1984}, note = {//LOCAL//NONE//}, month = {1984}, pages = {185-195}, abstract = {

We experimentally tested the hypothesis that simulated rainfall would trigger higher levels of activity in soil biota under large surface accumulation of litter in a Chihuahuan desert soil. Bacterial biomass was highest on days 6 and 12 in plots receiving simulated rain and increased with increasing litter. The turnover of themicrobial biomass was estimated as 6.97 days and was independent of either water or litter quantity. Soil respiration was higher in the wet treatments on days 0 and 6. When treatments were averaged across time, the highest soil respiration was in the 150 g m-2 litter, watered plots. The same pattern was observed in the dry treatments after natural rain events. On day 6, protozoa were higher in the wet plots; protozoa in the dry plots were 100\% cystic while those in the wet plots were 100\% trophic. Protozoan numbers were independent of litter quantity and reached the maximum on day 18. Amoebae were the dominant protozoa with an average population size of 25,000 g-1. Flagellates were intermediate in numbers (4,900 g-1) while ciliates were the least abundant (700 g-1).

}, keywords = {article, articles, journal, journals, litter,soil biota, microflora, protozoa, soil, simulated rainfall, soil biota, soil microflora, soil protozoa, soil respiration, trophic interactions, wet-dry cycles}, url = {/files/bibliography/Parker-etal_Pedobiologia_1984_v4_Effects-of-sim-rainfall-and-litter-on-soil-biota.pdf}, author = {L. W. Parker and D. W. Freckman and Yosef Steinberger and Driggers, L. and Walter G. Whitford} } @article {51926, title = {Effects of simulated rainfall and litter quantities on desert soil biota: nematodes and microarthropods}, journal = {Pedobiologia}, volume = {26}, year = {1984}, note = {//LOCAL//NONE//}, month = {1984}, pages = {267-274}, abstract = {

The experiments reported here were designed to test the hypothesis that numerical responses of soil fauna to simulated rainfall would occur only in soils having an adequate leaf litter cover. The soil microarthropods responded to artificial rainfall as hypothesized, that is, the most abundant taxa responded to litter quantity and moisture but not to moisture in the absence of sufficient substrate.

Desert soil fauna, eg. microarthropods and nemntodes, arc patchily distributed with thodivcl\&$\#$39;\lity and density varying as a !unction or leaf litter distribution and soil organic matter (S.INTOS el al. 1978; FRECKIIAN \& MANK.\U 1977). The accumulution or plant debris in patelws or varying size \•1\>JJCal\&$\#$39;\l to be a factor in the breakdown of surface litter in desert ecosystems. W111TFORD elal. (1982) and W1mPORD ti al. (1980) round relationships between quantities or surface litter aceumulations and rate of litter breakdown. Wn1TFOt,tD et al. (1982) also round that SUJ\>pression ol soil microartbropod, by chemical means reduced the rate or litter disap1\>earance and coneluded tlrnt soil microfauml were import.int in litter break down. Microarthropods are netive in surface litter accumulations for 2-4 hourô€Œ´ in the early morning even during 1\>eriods when the soil has no measureable moisture (1V\&$\#$39;mTFORO et al. J.981), but when the soil and litter ore wet, more indhridnals and more taxa can be extracted trom both soil nud litter. Jn our earlier work (WaITFORO et at. 1981) we found that simulated rainfall atrected the proportions ol the nematode J)opulation that were anbydrobiotic but found no changes in numbers following watô€Œµr addition such as that exhibited by soil rnirroarthropods. However tlrnt study was based on a single si1uulnted rainfall event (W111TYOH1) et al. 1981) which resulted iu large numerical responses of microartbropods iu 1mrfac\·e litter and in soil under litter accumulations. Nov-MEIR (1074) cmphasir.cd that water is the factor of overriding importanc\·e in desert eco,yste111s and stated that rainlall pulses must be i111portant stimulators ol soil biotic activity.The studies or distributions or soil laun11 (SAxTOS ct 111. 1978; FnAxc\" cl al. 1979) and Jitter disappearance - soil launn relationships (SAN1\&$\#$39;0S \& W111wo1m 198L; WHITFORD et al. 1982; W111noao el al. 1983) suggest that lor soil organisms, an adequate energy ancl nutrient impply in the form of l)lant litter is more important than waler as a lactor arr(\&$\#$39;{\&$\#$39;ting numeric\·al responses of soil fauna. The e::q1eriment.s reported here were designed to t(\&$\#$39;st the hypothesis that numerical responses. of soil fauna to simulated rainfall would otrnr only in soils having an adequate leaf litter cover.

}, keywords = {article, articles, journal, journals, litter,soil biota, microarthropod, nematode, rainfall simulation,soil biota, soil biota,litter}, url = {files/bibliography/84-Pedo-Whitford.pdf}, author = {Yosef Steinberger and D. W. Freckman and L. W. Parker and Walter G. Whitford} } @proceedings {51928, title = {Effects of desert vegetatoin on arid soils}, year = {1984}, month = {1984}, address = {Adelaide, Australia}, author = {J.M. Tromble} } @mastersthesis {51934, title = {Ecology of a sand sage community in southern New Mexico}, year = {1983}, note = {//NMSU//NONE//}, month = {1983}, pages = {71}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Sand sage (Artemisia filifolia Torr.), which is usually found as scattered individuals along arroyos and other more mesic areas in southern New Mexico, was found to be the dominant shrub species on a site in the generally xeric Parker Heights region of the New Mexico State University College Ranch. The site is bordered on the east and southeast by cresotebush (Larrea tridentata (D.C.) Colville), and by mesquite (Prosopis glandulosa Torr.), elsewhere....It was concluded from the data that the presence of the sand sage can be attributed to the ability of the soil to take up water very rapidly and store relativelly large quantities at greater depths. Therefore, more water is available for plant use on the site than in the surrounding communities.}, keywords = {Artemisia,community ecology, community, sand sage, dissertation, dissertations, ecology,sand sage community, sand sage community, shrub, Artemisia, shrub, Larrea, shrub, Prosopis, theses, thesis}, author = {T.L. Atwood} } @article {51955, title = {Effects of early weaning and lambing time on accelerated lambing in Polypay sheep}, journal = {Theriogenology}, volume = {20}, year = {1983}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1983. (http://www.sciencedirect.com/science/journal/0093691X)}, month = {August 1, 1983}, pages = {141-149}, abstract = {

Effects of early weaning, lactation, and day-of-year lambing on the ability of Polypay ewes to rebreed following winter and summer lambings were evaluated. Winter lambing ewes did not successfully rebreed while lactating. However, when winter-born lambs were weaned at 31 days postpartum, more ewes rebred and produced summer lambs (35.7\%) than when lambs were weaned at 41 days postpartum (23.6\%). Ewes that lambed during the early part of the winter lambing period had an advantage over later lambing ewes in the percentage which subsequently lambed the following summer. This was apparently the result of a difference in length of breeding exposure rather than a higher fertility rate during the early part of the breeding period. When summer lambing ewes were rebred during the early part of the summer breeding period (late summer to early fall), stress associated with lactation did not affect subsequent winter lambing performance. Summer lambing ewes belonging to a late weaning (80 days) treatment group did not differ (P\>0.05) from those belonging to an early weaning (31 days) treatment group in winter fertility, prolificacy, day-of-year lambing or lambing interval.

}, keywords = {early, effects, lambing, Polypay sheep, weaning}, doi = {10.1016/0093-691X(83)90209-1}, url = {/files/bibliography/243.pdf}, author = {Clarence V. Hulet and Stellflug, J.N. and A. D. Knight} } @article {51957, title = {Environmental sampling for monitoring rangeland condition}, year = {1983}, note = {//USDA, NMSU//NONE//}, month = {1983}, institution = {University of Arizona}, address = {Tucson, Arizona}, abstract = {Selected environmental variables were evaluated for their utility as indicators of rangeland change and their potential for remote sensing. Eighty-five study sites were sampled in souther New Mexico. Total vegetation cover and the ration of shrub cover to grass cover were related to disturbance. Increasing degrees of change were associated with a decrease in total vegetation cover, and increase in the ration of shrub to grass cover and decrease in organic soil cover (litter and algal crusts). Total vegetation cover and organic soil cover can be monitored from single-date satellite data, but total vegetation cover alone may provide ambiguous results. The ration of shrub to grass cover, which is necessary to identify the direction of change can be determined by examining multi-date satellite data that correspond to the times when grasses and shrubs exhibit their maximum green biomass.}, keywords = {book, books, chapter, chapters, community, vegetation change, grassland, vegetation change, remote sensing, soil, remote sensing, vegetation, report, reports, shrub, vegetation change, soil erosion, soil texture, vegetation change}, isbn = {Final Report of NASA/NSTL/ERL Contract No. 13-172}, author = {Charles F. Hutchinson and Warren, Peter L.} } @mastersthesis {51963, title = {Examination of field techniques for the estimation of above ground biomass on five Chihuahuan Desert shrub species}, year = {1983}, note = {//LOCAL//NONE//}, month = {1983}, pages = {27}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {A group of common Chihuahuan Desert shrubs having highly varied growth forms were studied in an attempt to see if standardized field measurement techniques could be used for the prediction of above ground biomass. The most efficient (best estimation for least time expenditure) field measurement was obtained for each species. It was found that the techniques yielded reliable results for plants which were of medium to large size for the species, but biomass predictions were unreliable from measurements made upon plants which were small (reproduction) for the species. It was found that it is not necessary to obtain volume or canopy area values to estimate biomass, but that single field measurements could be used. Formulas were developed for these measurements. The biomass of two species, Larrea tridentata and Acacia constricta, which have growth forms resembling an inverted cone, could be most efficiently estimated using a single field measurement-internal height. In the case of two other species, Gutierrezia sarothrae and Krameria parvifolia, which tend to be more compact and regularly globose a single measurement-maximum diameter was the most efficient biomass estimator. External height measurements were found to be the best for Flourensia cernua.}, keywords = {Acacia,biomass estimate, biomass,shrub, dissertation, dissertations, Flourensia,biomass estimate, Gutierrezia,also SEE Xanthocephalum sarothrae (Pursh) Shinners) and other species on semidesert grasslands of southern New Mexico}, year = {1982}, note = {//??//NONE//}, month = {1982}, pages = {207}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, theses, thesis, Xanthocephalum,establishment}, author = {Abdelgader Osman} } @article {52013, title = {The effects of subterranean termite removal on desert soil nitrogen and ephemeral flora}, journal = {Journal of Arid Environments}, volume = {5}, year = {1982}, note = {//NMSU//NONE, LTER//}, month = {1982}, pages = {53-59}, abstract = {

Total soil nitrogen and ephemeral plant density and biomass on plots treated with chlordane to eliminate termites were compared with untreated control plots at the Jornada validation site in the Chihuahuan desert. Total soil nitrogen in the 0-2.5 and 10-20 cm depths was significantly higher for treated compared to control plots. Other than increase soil N at the above two depths, the elimination of termites did not alter the spatial distribution of nitrogen around Larrea tridentata. Soil N in both treated and controlled plots was higher under the shrub canopy than in open areas, on the east side of shrubs than on the west, and in the surface soils than at lower depths.

}, keywords = {Amitermes, article, articles, Chlordane, ephemeral flora,termite effects, flora, SEE , Gnathamitermes, journal, journals, pesticide, Chlordane, soil,nitrogen, subterranean termite, SEE , termite, Chlordane, termite, ephemeral flora, termite, soil nitrogen, termite,Amitermes, termite,Gnathamitermes}, doi = {10.1016/S0140-1963(18)31463-0}, url = {files/bibliography/JRN00003.pdf}, author = {L. W. Parker and Harold G. Fowler and George Ettershank and Walter G. Whitford} } @mastersthesis {52015, title = {The effects of brush control on bird populations in a mesquite community}, year = {1982}, note = {//USDA//NONE//}, month = {1982}, pages = {55}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {This study dealt with the effects that brush control, by aerial applications of 2,4,5-T (2,4,5-Trichlorophenoxy acetic acid) had on indigenous bird populations in a mesquite community in southern New Mexico. Vegetation comparisons indicate that the mesquite was killed more completely in the duny areas than in the flat areas. Treatment effects on bird populations were examined via the parameters of species richness, dominance composition, diversity, activity, and total numbers. Species richness was greater in the unsprayed area in the duny subtype, but was approximately equal in sprayed and unsprayed areas in the flats. Dominance composition differed little between treatment areas. In 1979, three species were restricted to the duny subtype, but only one species was restricted to the unsprayed portion of this subtype. In 1980, only one species was restricted to the duny subtype. The evidence for an effect on bird diversity was weak, but may indicate a lower diversity in the sprayed duny mesquite. Activity was lower in the sprayed duny and the sprayed flat mesquite areas as compared to their respective unsprayed areas in 1979, but only in the sprayed duny area in 1980. Based on total numbers observed for each species, the mesquite control had a detrimental effect on eight species; however, five species may have benefited by mesquite control. In conclusion, it appears that mesquite control has a detrimental effect on populations of some bird species. These differences are more pronounced in the first year of study, possibly because of the mesquite regrowth which occurred the following year.}, keywords = {bird population, brush control, brush control, herbicide, brush control, Prosopis, community, mesquite, bird populations, dissertation, dissertations, herbicide,"2,4,5-T", mesquite community, also SEE , Prosopis, bird population, Prosopis, brush control, theses, thesis}, author = {J.A. Reitzel} } @conference {52017, title = {Effect of defoliation and ambient temperature on photosynthesis and diurnal root respiration of Kleingrass (Panicum coloratum L.) in the field}, booktitle = {35th Annual Meeting, Society for Range Management}, year = {1982}, month = {1982}, author = {Sisson, W.B.} } @article {52023, title = {Effects of initial litter accumulation and climate on litter disappearance in a desert ecosystem}, journal = {The American Midland Naturalist}, volume = {108}, number = {1}, year = {1982}, note = {//NMSU//NONE//}, month = {1982}, pages = {105-110}, abstract = {

We examined monthly litter disappearance from initial concentrations of 50g, 100g, 150g and 200g m-2. Approximately 35\%-50\% of the litter disappeared each month from May-September. In March and April litterfall input exceeded litter loss. Litter loss was consistently higher in the 100g m-2 accumulation than from the other concentrations. Stepwise regression analysis showed that litter loss varied as a function of soil temperature at 15 cm (r2= 0.40) and that initial litter quantity was the second most important variable (increased r2 to 0.45). Monthly litter disappearance was apparently independent of monthly rainfall. Abiotic variables gave an r2 of 0.48, suggesting that much of the seasonal variation in litter disappearance is attributable to the soil biota. Suppression of microarthropods by treating the soil with chlordane insecticide resulted in marked reduction in litter disappearance.

}, keywords = {article, articles, decomposition, abiotic factors, decomposition, microarthropods, decomposition,litter, herbicide, chlordane, journal, journals, Larrea,decomposition, litter,decomposition}, doi = { 10.2307/2425298 }, url = {files/bibliography/82-AmMdlndNtrlt-Whitford.pdf}, author = {Walter G. Whitford and Robert Repass and L. W. Parker and Ned Z. Elkins} } @mastersthesis {52047, title = {Environmental factors affecting postweaning growth in hereford cattle}, year = {1981}, note = {//??//NONE//}, month = {1981}, pages = {40}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle, productivity, dissertation, dissertations, theses, thesis}, author = {Montshiwa, K. Mosana} } @article {52051, title = {The effects of microarthropods on litter decomposition in a Chihuahuan Desert ecosystem}, journal = {Ecology}, volume = {62}, year = {1981}, note = {//NMSU//US-IBP//}, month = {1981}, pages = {654-663}, abstract = {

We compared decomposition of surface and buried, untreated, mixed desert shrub litter to that of insecticide- and fungicide-treated litter. Suppression of fungi reduced decomposition by ~29\%; exclusion of microarthropods reduced decomposition by ~53\%. Approximately 55\% of the organic mass of the untreated litter disappeared during the 6-mo growing season and 23-29\% disappeared in the winter months (November through March). There was a consistent pattern of microarthropod colonization of buried litter that was related to the percent organic matter lost. This sequence tydeid mites, trasonemid and pyemotid mites, gamasina and predatory Prostigmata, Collembola and Psocoptera, and oribatids. After 1 yr, large numbers of enchytraeid worms were extracted from buried litter. Decomposition of insecticide-treated litter varied directly with rainfall and soil temperature while abiotic factors accounted for \<50\% of the variation in decomposition of untreated buried litter. We hypothesize that microarthropods affect litter decomposition in desert ecosystems by inoculating litter with fungal spores, but grazing on fungi, and in a heretofore undescribed mode, by preying on free-living nematodes.

}, keywords = {article, articles, enchytraeids, fungi, fungicide, Benomyl, fungicide, Dexon, insecticide, insecticide, Chlordane, invertebrate,enchytraids, journal, journals, Larrea, litter decomposition, litter decomposition,microarthropods, microarthropod, litter decomposition, mite, mite, tydeid, nematode, predation, microarthropods, psocoptera, soil microarthropods, termite, litter decomposition}, url = {files/bibliography/81-Ecology-Whitford.pdf}, author = {Perseu F. Santos and Walter G. Whitford} } @article {52062, title = {Exceptions to the AET model: deserts and clear-cut forest}, journal = {Ecology}, volume = {62}, number = {1}, year = {1981}, note = {//NMSU//NONE//}, month = {1981}, pages = {275-277}, abstract = {

Here, we show that the attractive correlation between AET and decomposition does not necessarily apply to all vegetation types nor to severely disturbed sites. Decomposition is higher than predicted by the AET model in deserts where AET is low, and lower than predicted for a mesic clear-cut forest where AET values are higher than uncut forests. We suggest that the attractive simplicity of the AET decomposition relationship fails in these systems because it does not account for marked changes in microclimate produced by ecosystem perturbation like clear-cutting, or for biotic adaptations in desert ecosystems.

}, keywords = {article, articles, evapotranspiration,model, journal, journals, model, decomposition, model,evapotranspiration}, doi = {10.2307/1936687 }, url = {files/bibliography/81-Ecology62-Whitford.pdf}, author = {Walter G. Whitford and Meentemeyer, V. and Timothy R Seastedt and Cromack, K. Jr. and Crossley, D. A. Jr. and Perseu F. Santos and Todd, R. L. and Waide, J. B.} } @article {52068, title = {Effects of vegetation change on ant communities of arid rangelands}, journal = {Environmental Entomology}, volume = {10}, year = {1981}, note = {//USDA//NONE//}, month = {1981}, pages = {893-897}, abstract = {

We compared the density and diversity of ant colonies on areas where the vegetation had been altered by treatment with herbicides and on untreated areas. Highest densities of ant colonies were on the untreated mesquite dune habitat and the grassland habitat. The treated habitats were characterized by differences in shrub cover and composition and cover of forbs and grasses. Conomyrma bicolor and Solenopsis xyloni Were significantly more numerous on the mesquite dunes and grassland, respectively. The fungus-culturing ant, Trachymyrmex smithi, was abundant on the treated dune habitats and absent in the grassland habitat. Ant communities were most similar on the two sites subjected to vegetation modification, and most different comparing those dune habitats with the untreated mesquite dunes.

}, keywords = {ant, diversity, ant, herbicide, ant,density, ant,vegetation change, arthropod, also SEE , article, articles, brush control, herbicide, community,ant, herbicide,rangeland, journal, journals}, doi = {10.1007/978-3-319-56928-4_6}, url = {files/bibliography/81-AdvinGloblChngeRes-Whitford.pdf}, author = {Wendy Wisdom and Walter G. Whitford} } @proceedings {52072, title = {Electronic weighing, identification and subdermal body temperature sensing of range livestock}, year = {1980}, note = {Reproduced by kind permission of CSIRO PUBLISHING, Melbourne Australia, from Forage evaluation: concepts and techniques: proceedings of a workshop entitled {\textquoteright}Forage evaluation and utilization - an appraisal of concepts and techniques{\textquoteright}held in Armidale, N.S.W., 27-31 October, 1980, under the auspices of the U.S./Australia Cooperative Science Program / editors: J.L. Wheeler, R.D. Mochrie. Published jointly by CSIRO Australia and the American Forage and Grassland Council, 1981.}, month = {October 27-31, 1}, pages = {373-382}, address = {Armidale, NSW, Australia}, abstract = {Individual animal weights can be obtained manually or automatically in a computer-compatible format with an electronic scale. If an electronic identification, subdermal body temperature sensing unit is interfaced with an electronic scale, the weight, identification and subdermal body temperature of individually identified animals can be obtained either manually or automatically, thus eliminating transcriptional and phonetic errors. Electronics can be used at remote locations despite extreme temperatures, dust and fluctuation in battery power. For research purposes, daily weight fluctuations, watering behavior and subdermal body temperature can be recorded continuously. When the system becomes commercially available, increased livestock production at a lower cost will be possible.}, keywords = {electronic weighing, identification, range livestock, subdermal body temperature}, url = {/files/bibliography/192.pdf}, author = {D.M. Anderson and Landt, J.A. and Salazar, P.H.} } @article {52073, title = {Electronic Identification October 1, 1978 - September 30, 1979}, number = {LA-8315-PR Progress Report}, year = {1980}, month = {October 1, 1978 }, pages = {47}, abstract = {Livestock field testing of the electronic identification system has commenced with experiments conducted at the Jornada Experimental Range in Las Cruces, New Mexico. Five other sites which have been selected will be phased in during the comming year. The concept of electronic identification and temperature monitoring of livestock will then be tested in dairy, feedlot and open range environments to demonstrate its commercial application and feasibility. Work at Los Alamos Scientific Laboratory on the identification equipment has been directed toward improving the transponder package design and increasing the sensitivity of the receiver to the reflected transponder signal. Favorable results were obtained from the use of a hobby microcomputer in the electronic identification system. This indicates that the system is compatible with a low budget commercial system affordable to small livestock operations. A considerable amount of work has also been done relating to temperature-monitoring capability of the system because a great deal of difficulty is anticipated in making this a useful tool in the field trials. A radio telemetric physiological onitoring system has been assembled for use in monitoring animal temperature, and biological experiments have been done to test the acceptability of subdermal temperature monitoring in livestock.}, keywords = {electronic identification, livestock field testing}, isbn = {LA-8315-PR Progress Report}, url = {/files/bibliography/178.pdf}, author = {Araki, C.T. and Landt, J.A. and Holm, D.M. and Brown, R.R. and Seawright, G.L. and Payne, R.J. and D.M. Anderson} } @article {52137, title = {The effects of irradiating adaxial or abaxial leaf surface on the rate of net photosynthesis of Perezia nana and Helianthus annuus}, journal = {Photosynthetica}, volume = {13}, number = {3}, year = {1979}, note = {//NMSU//US-IBP//}, month = {1979}, pages = {287-293}, abstract = {Net photosynthetic rate (Pn) and leaf resistance (r1) to transpiration were evaluated while irradiating either the adaxial or abaxial leaf surfaces of Perezia nana (desert holly) and Helianthus annus (sunflower). The P. nana leaves are anatomically isolateral, borne vertically, and equal numbers of leaves are oriented in each of the four cardinal directions. H. annus leaves are borne horizontally and are anatomically anisolateral. P. nana showed no significant differences between Pn and r1 of the two surfaces whereas H. annus did. These data are discussed with respect to leaf display, mesophyll anatomy and stomatal density.}, keywords = {article, articles, evapotranspiration,Perezia, Helianthus,photosynthesis, journal, journals, Perezia,photosynthesis, photosynthesis,Helianthus, photosynthesis,Perezia, physiology,plant}, author = {J. P. Syvertsen and Gary L. Cunningham} } @mastersthesis {52148, title = {Energy allocation in desert winter annuals: test of the r- and k- selection theory}, year = {1978}, note = {//NMSU//NONE//}, month = {1978}, pages = {77}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Populations of three winter annuals were sampled in two or more of the U.S. southwestern deserts: Mojave, Sonoran, and Chihuahuan. These deserts represent different levels of environmental predictability as defined by rainfall patterns. The Mojave has the most winter rainfall and the Chihuahuan has the least winter rainfall, with the Sonoran intermediate. Collections of approximately 30 individuals of each species took place in a number of sites where the species occurred in each desert. Sites varied greatly in topography and soils. The purpose of this study was to determine if reproductive allocation varied between populations within and between deserts as predicted by the concept of r-K selection. For each species, large variations in reproductive allocation were found between populations sampled within a desert. The differences between sites could be paritally expelained by the difference in the topography and soils of the colleciton sites. No consistent differences were found in reproductive, vegetative or root allocation between populations of different deserts, relative to r- and K-selection theory. Dewert annuals appear to ahve adapted to unpredicatble rainfall patterns by methods different than simply increasing reproductive allocation, indicating that not all adjustments in life-history strategies cna be explained by invoking the r- and K-selection theory.}, keywords = {annual plant, reproduction, dissertation, dissertations, reproduction, annual plants, selection theory,annual plants, theses, thesis}, author = {Elaine DePree} } @article {52149, title = {Effects of nitrogen fertilization on primary production in a Chihuahuan Desert ecosystem}, journal = {Journal of Arid Environments}, volume = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {135-139}, abstract = {

In a Chihuahuan desert ecosytem, the growth responses to nitrogen amendment of a perennial shrub (creosotebush, Larrea tridentata) and a perennial grass (fluff grass, Erioneuron pulchellum) were made twice during the growing season: first during a period of average rainfall, then during a period of above average rainfall. Fluff grass exhibited a marked increase in biomass to 25 kg ha-1 and 100 kg ha-1 nitrogen fertilization. Creosotebush increased biomass production only at the higher level during both periods. These results suggest that productivity of a Chihuahuan desert system is partially nitrogen limited and that shallow-rooted plants utilized the available nitrogen at the 25 kg ha-1 fertilization level, thus making it unavailable to creosotebush.

}, keywords = {article, articles, creosotebush, SEE , Erioneuron,nitrogen fertilization, Erioneuron,primary production, fertilization amendment, grass, Erioneuron, journal, journals, Larrea, also SEE , Larrea,nitrogen fertilization, Larrea,primary production, nitrogen fertilization,Erioneuron, nitrogen fertilization,Larrea, primary production, Erioneuron, primary production,Larrea}, doi = {10.1016/S0140-1963(18)31738-5}, url = {files/bibliography/78-JnlArdEnvnmnts-Whitford.pdf}, author = {George Ettershank and Jennifer Ettershank and Bryant, Martha and Walter G. Whitford} } @conference {52159, title = {Effects of range condition on summer steer gains}, booktitle = {31st Annual Meeting, Society for Range Management}, year = {1978}, month = {1978}, pages = {11-12}, keywords = {range condition, summer steer gains}, author = {J. K. Lewis and J. Lacey and Gibbens, Robert P. and Heintz, J. and Herndon, J. and Blome, L.} } @article {52169, title = {Energy dynamics of vegetative and reproductive growth in Spanish bayonet (Yucca baccata Torr.)}, journal = {The Southwestern Naturalist}, volume = {23}, number = {3}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {409-422}, abstract = {

Yucca baccata and Yucca elata are Chihuahuan desert plants which develop massive inflorescence stalks, large flowers and heavy fruits. A field study on the NMSU College Ranch found an average Y. baccata invests over 250 g of biomass (oven dry) into these reproductive structures, with about half of this in fruits. Its fruits are strongly affected by the yucca moth whose larvae develop inside the fruit and consume the maturing seeds. A comparative laboratory study found the optimum net photosynthesis rate of Y. baccata leaves below 25 C, whereas Y. elata leaves had an optimum above 30 C, assuming equivalent moisture and irradiance levels. These physiological differences correlate well with their observed patterns of vegetative and reproductive growth. Y. baccata grows better in cooler seasons and sites than Y. elata. A computer simulation study of reproductive and vegetative growth in Y. baccata indicated that an average-sized plant needs about 10-12\% of its dry biomass as stored carbohydrates in order to produce an average-sized inflorescence with flowers and fruits. A lesser amount resulted in depletion of stored energy to less than 1\%. Depending on environmental conditions, the simulation indicated that about three years were required to rebuild energy to the level needed for another reproductive effort.

}, keywords = {article, articles, journal, journals, photosynthesis, Yucca, physiology, Yucca, plant,spanish bayonet,Yucca, reproduction,Yucca, Yucca, energy dynamics, Yucca, photosynthesis, Yucca,physiology, Yucca,reproduction}, doi = {10.2307/3670249 }, url = {/files/bibliography/354.pdf}, author = {Wallen, Deborah R. and J. Ludwig} } @article {52175, title = {Effects of shrub defoliation on grass cover and rodent species in Chihuahuan Desert ecosystem}, journal = {Journal of Arid Environments}, volume = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {237-242}, abstract = {

Treatment of a nine-hectare desert shrub community with an herbicide (dicamba) resulted in reduction of the live canopy of creosotebush, Larrea tridentata, and an increase in coverage of bush muhly, Muhlenbergia porteri. After treatment, Dipodomys merriami was replaced by Dipodomys ordii as the dominant species. On untreated control areas, D. merriami maintained dominance. These changes are interpreted to result from a release of growth inhibition of M. porteri by creosotebush and habitat structure selection in Dipodomys.

}, keywords = {article, articles, Dipodomys,shrub defoliation, grass cover,shrub defoliation, herbicide, dicamba, journal, journals, Larrea,defoliation, Muhlenbergia,shrub defoliation, rodent,shrub defoliation, shrub defoliation, shrub defoliation,grass cover, shrub defoliation,rodents, shrub,defoliation}, url = {files/bibliography/78-.JAE-Whitford.pdf}, author = {Walter G. Whitford and Dick-Peddie, Scott and Walters, David and J. Ludwig} } @article {52176, title = {The effects of twig girdlers (Cerambycidae) and node borers (Bostrichidae) on primary production in mesquite (Prosopis glandulosa)}, journal = {Journal of Arid Environments}, volume = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {345-350}, abstract = {

Production of leaves and shoots on branches of mesquite shrubs which had been girdled by the mesquite twig girdler (Oncideres rhodisticta) was compared with the production of unaffected branches on girdled and ungridled shrubs. We made similar comparisons on mesquite which had been subjected to simulated girdling or terminal node destruction of 40-80 per cent of the branches. There was no significant difference in shoot and leaf growth in either natural or simulated damaged plants compared to controls. These studies suggest that the timing of the activity of stem-destroying insects may be important in minimizing damage to the plant.

}, keywords = {article, articles, Bostrichidae, Cerambycidae, journal, journals, node borer, primary production, Prosopis, Prosopis,node borer, Prosopis,twig girdler, twig girdler}, doi = {10.1016/S0140-1963(18)31715-4}, url = {files/bibliography/78-JournalArdEnvnmnts-Whitford.pdf}, author = {Walter G. Whitford and D. J. DePree and R. K. Johnson} } @article {52179, title = {The effect of non-structural carbohydrate levels on dark CO2 release in creosotebush}, journal = {Photosynthetica}, volume = {11}, number = {3}, year = {1977}, note = {//NMSU//US-IBP//}, month = {1977}, pages = {291-295}, abstract = {The effect of substrate levels on the rate of dark respiration of shoots of the warm desert evergreen perennial, Larrea tridentata DC Cov., was investigated. Rates of dark CO2 release were compared to both the concentration of total nonstructural carbohydrates (TNC) and the amount of CO2 accumulated during the light period immediately preceding the dark CO2 release measurements. Levels of TNC were measured at the beginning of an experiment and estimated during the course of an experiment from CO2 exchange data. The rate of dark CO2 release is a function of TNC concentration and not a function of CO2 accumulated in the preceding light period except when TNC concentrations are extremely low.}, keywords = {article, articles, carbon dioxide, Larrea, journal, journals, Larrea, carbohydrates, Larrea, carbon dioxide, model, CO2 exchange, Larrea, photosynthesis, Larrea}, author = {Gary L. Cunningham and J. P. Syvertsen} } @article {52186, title = {Environmental physiology of the banner-tailed kangaroo rat - II. influences of the burrow environment on metabolism and water loss}, journal = {Comparative Biochemistry and Physiology}, volume = {57A}, year = {1977}, note = {//NMSU//US-IBP//}, month = {1977}, pages = {471-477}, abstract = {1. Oxygen consumption and evaporative water loss were measured in response to burrow and control temperature, water vapor pressure and inspired CO2 concentration for Dipodomys spectabilis. 2. Oxygen uptake of banner-tail kangaroo rats increased in response to increased inspired CO2 and decreased temperature. 3. Oxygen consumption of the kangaroo rats decreased in response to a combination of elevated CO2 and water vapor pressure, relative to elevated CO2 in dry air, but there was no consistent response to increased water vapor pressure, alone or in combination with temperature. 4. Evaporative water loss and heat loss decreased with decreasing temperature and/or increasing water vapor pressure, but water loss increased at elevated inspired CO2 concentrations and decreased in response to the combination of elevated CO2 and water vapor. 5. Seasonal acclimatization of oxygen consumption was evident when data were plotted as responses to control exposures by month. 6. Oxygen uptake and heat loss measured under burrow conditions were related to the seasonal thermal cycle, in that metabolism decreased and heat loss increased during the months of highest burrow temperatures. 7. Evaporative water loss showed little seasonal change under either control or burrow conditions, but had a slight increase in September and October, months in which burrow water vapor pressure was reduced.}, keywords = {article, articles, Dipodomys, burrow environment, Dipodomys, physiology, journal, journals, rodent, bannertailed kangaroo rat, Dipodomys, rodent, Dipodomys, rodent, physiology}, author = {F. R. Kay} } @mastersthesis {52182, title = {Effects of range supplementation and season on botanical composition of cattle diets}, year = {1977}, note = {//NMSU//NONE//}, month = {1977}, pages = {41}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {botanical composition, cattle grazing,diet, cattle, diet, diet,cattle, dissertation, dissertations, range supplementation,cattle diet, theses, thesis}, author = {Gonz{\'a}lez Rodr{\'\i}guez, Jorge Karim} } @article {52203, title = {Ecological relationships in a desert anuran community}, journal = {Herpetologica}, volume = {32}, number = {1}, year = {1976}, note = {//NMSU//NONE//}, month = {1976}, pages = {7-18}, abstract = {

The surface activity and distribution patterns of five species of anurans inhabiting a watershed in the Chihuahuan Desert were studied from 1970-1974. Adult toads Bufo debilis, Bufo cognatus, Scaphiopus hammondi, Scaphiopus bombifrons and Scaphiopus couchi exhibited short periods of activity immediately following rain events. Juveniles of these species were active for as long as 55 days in the bottom of the ephemeral lake where vegetative cover and fissures in the clay-silt soil provided shelter and modified the microclimate due to reduced evaporation. Less than 1\% of the juveniles of S. bombifrons, S. hammondi and B. debilis survived to adult size. The importance of spatial separation within the flooded playa during breeding and possible character displacment of breeding calls are documented and their importance in maintaining this desert anuran community is discussed.

}, keywords = {amphibian, breeding, amphibian,activity, amphibian,Bufo, amphibian,Scaphiopus, anuran community, article, articles, ecology,anuran community, journal, journals, Scaphiopus, activity}, url = {files/bibliography/76-Herp-Whitford.pdf}, author = {Creusere, F. Michael and Walter G. Whitford} } @mastersthesis {52210, title = {The effect of grazing on vine mesquite (Panicum obtusum H.B.K.)}, year = {1976}, note = {//NMSU//NONE//}, month = {1976}, pages = {37}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The effect of grazing on vine mesquite (Panicum obtusum H.B.K.) was studied on a playa lake on the New Mexico State University Research Ranch between June 20, 1975, and October 11, 1975. The playa was about 40 acres, but the total fenced area was about 72 acres, i.e., the playa was encompassed within the total study area.... Stem plant material production was significantly different (P<.05) between the control and the north or south pasture. There was no significant difference between the stem production in the north and south pastures.}, keywords = {cattle grazing,Panicum, dissertation, dissertations, grass,Panicum, management,Panicum, Panicum,grazing, playa, grazing, rangeland, theses, thesis, vine mesquite, SEE }, author = {Musa, Yusufu} } @mastersthesis {52215, title = {Effects of grazing on herbage dynamics of vine mesquite (Panicum obtusum H.B.K.)}, year = {1976}, note = {//NMSU//NONE//}, month = {1976}, pages = {58}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The study reported herein was conducted to evaluate the effect of different degrees of grazing intensity on biomass production, rate of regrowth, vegetative reproduction, and vigor of vine mesquite grass (Panicum obtusum H.B.K.). The research took place during two grazing seasons (June 20, 1975 to October 11, 1975 and June 16, 1976 to August 30, 1976) on a playa lake which had not been grazed since 1971 on the New Mexico State University College Ranch. The study showed greater (P<.05) live-herbage biomass, standing dead and litter biomass, stolon production and mean plant heights in the control pasture than in the moderate or heavy grazing treatments during both seasons.... The study also showed significant (P<.05) differences in live-herbage biomass, standing dead and litter biomass production between sampling dates within the control treatment during both seasons.}, keywords = {cattle grazing, Panicum, dissertation, dissertations, grazing management,Panicum, Panicum,grazing, plant,Panicum, theses, thesis}, author = {Suleiman, Habibu} } @article {52223, title = {Environmental factors influencing semidesert grassland perennial grass demography}, journal = {Southwest Naturalist}, volume = {21}, year = {1976}, month = {1976}, pages = {259-274}, abstract = {Long-term chart quadrat records from the Jornada Experimental Range in south-central New Mexico were photographed, the negatives analyzed with a flying-spot scanner, and the information converted for computer analyses. Some 35 quadrats with data from about 30 to 50 years duration were used, giving records on the life span of 12,437 perennial grass plants of seven species. Maximum life spans varied from 28 years for Boutelouaeripoda to only 7 years for Hilariaarnica. Mean life span for plants living at least 1 year varied from 3.8 to 3.0 years for these species. Average age-specific survival rates for seven perennial grasses increased from 0.39 at age 1 up to a maximum of 0.68 at age 7 and down to 0.48 at age 12. The level of grazing over the past years had little effect on plant arrival but cattle movement and trampling caused the death of some newly established grasses. A water-budget model produced results that could be readily interpreted in understanding plant survival. The relationship between the number of days of effective moisture in a given time period and the age-specific survival rates for each age class was pronounced. The period between the second and fourth age classes was most critical as regards availability of water. For newly established plants with shallow root systems, the precipitation of the immediate growing season was more important than precipitation for longer antecedent intervals.}, url = {/files/bibliography/158.pdf}, author = {R. G. Wright and G.M. Van Dyne} } @article {52238, title = {Environmental physiology of the banner-tailed kangaroo rat - I. Influences of ambient temperature, humidity, and carbon dioxide on body temperature}, journal = {Comparative Biochemistry and Physiology}, volume = {50A}, year = {1975}, note = {//NMSU//US-IBP//}, month = {1975}, pages = {483-488}, abstract = {1. Mean body temperature of Dipodomys spectabilis acclimated to 25 C was constant at ambient temperatures form -5 to 15 C, and was reduced int eh thermoneutral zone (20-30 C). 2. Lethal air temperature was 40 C. 3. There was no apparent response of body temperature to levels of CO2 normally found in the burrow environment. 4. There was a suggestion of decreased body temperature at decreased vapor density or increased saturation deficit. 5. The major factor affecting body temperature of D. spectabilis was ambient temperature.}, keywords = {article, articles, banner-tailed kangaroo rat, Dipodomys,physiology, journal, journals, physiology, banner-tailed kangaroo rat, rodent, banner-tailed kangaroo rat, rodent, Dipodomys}, author = {F. R. Kay} } @mastersthesis {52266, title = {The ecology of the desert dwelling salamander Ambystoma tigrinum}, year = {1974}, note = {//LOCAL//NONE//}, month = {1974}, pages = {68}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {The tiger salamander, Ambystoma tigrinum, inhabits temporary desert ponds in southern New Mexico. The ponds, called playas and cattle tanks hold accumulated rain water runoff from intense summer storms for irregular intervals from months to years. The primary productivity of these ponds ecosystems is low, and the major energy source is allochthonous organic material used for heterotrophic productivity. The tiger salamander forms the highest trophic level in the pond ecosystem. Domination of the invertebrate community shifts from phyllopods immediately following pond flooding to aquatic insects in ponds lasting several months or more....A comparison of the habitat utilization of deserticolous anurans and urodeles is presented and the advantages of inhabiting temporary desert ponds is discussed. Neoteny, cannibalism, and differential transformation rates prepare aquatic tiger salamanders for the subterranean habitat.}, keywords = {Ambystoma, life history, amphibian, Ambystoma, amphibian,tiger salamander,Ambystoma, dissertation, dissertations, theses, thesis}, author = {Jeff Delson} } @article {52296, title = {The effect of carbonate deposition layers (caliche) on the water status of Larrea divaricata}, journal = {The American Midland Naturalist}, volume = {90}, number = {2}, year = {1973}, note = {//LOCAL//NONE//}, month = {1973}, pages = {474-480}, abstract = {The seasonal pattern of water status of Larrea divaricata was measured on three sites in southern New Mexico. One site had no carbonate deposition layer. One site had a carbonate deposition layer at a depth of 15 cm and the third had carbonate deposition at a depth of 25 cm. Larrea shrubs on sites with no carbonate deposition layer experienced less water stress during periods of greater precipitation. However, plants on sites with carbonate deposition layers showed less water stress when precipitation was low. These differences may in part account for local variations in size, density and pattern of spatial distribution of Larrea.}, keywords = {article, articles, calcium carbonate, deposition layers, caliche,Larrea, carbonate, SEE , journal, journals, Larrea,caliche, Larrea,water status}, author = {Gary L. Cunningham and J. H. Burk} } @mastersthesis {52315, title = {An evaluation of feedlot performance of Brangus, Hereford, and reciprocal crossbred steers}, year = {1973}, note = {//NMSU//NONE//}, month = {1973}, pages = {47}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {In 1966 New Mexico State University initiated a study to evaluate the performance of Brangus and Hereford cows in two distinct environments: Fort Stanton, a hilly grama grass environment, and the College Ranch, a desert grassland environment; and the performance of their straightbred and reciprocally crossbred steer calves in feedlot and carcass traits. The overall correlations between traits were: feed efficiency and average daily gain, r= -.58; feed efficiency and feed consumption, r= +.22; average daily gain and feed consumption, r= +.66.}, keywords = {cattle, food habits, cattle, genetics, cattle, management, cattle, productivity, dissertation, dissertations, theses, thesis}, author = {Shafer, Scott Malcolm} } @mastersthesis {52326, title = {Endomycorrhizae on desert plants with primary emphasis on Prosopis juliflora}, year = {1973}, note = {//NMSU//NONE//}, month = {1973}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {Roots of thirteen different species of desert plants were examined for the presence of mycorrhizae. Eleven of the thirteen plants contained endomycorrhizae, while none of the plants were found to possess ectomycorrhizae. Prosopis juliflora, Yucca elata, Opuntia sp., and Larrea tridentata contained sufficient endomycorrhizae in the root tissue to augment or assist the plants absorptive system. A more extensive study was performed on P. juliflora roots from greenhouse and field grown plants of approximately the same size and age to determine the distribution of endomycorrhizae within these roots. Endomycorrhizae were found in all the major branches from the mesquite taproot along with secondaries and tertiaries located in the top 25 cm of soil, but were never found in the taproot itself or the stem. Mycorrhizal spore distribution around P. juliflora was also determined. Two different spores were found in the soil around the mesquite roots. The distribution of Glomus fasciculatus spores in the soil followed closely the concentration and distribution of the mycorrhizae in the root. The results obtained to establish this relationship are diagrammatically summarized. Distribution of Glomus macrocarpus spores appeared to indicate no relationship of this spore with the concentration and distribution of mesquite roots.}, keywords = {dissertation, dissertations, endomycorrhizae,Prosopis, fungi, endomycorrhizae, Prosopis,endomycorrhizae, theses, thesis}, author = {Wilson, Steven Allen} } @inbook {52337, title = {Environmental modification for seedling establishment}, booktitle = {Biology and Utilization of Grasses}, year = {1972}, month = {1972}, pages = {101-114}, publisher = {Academic Press}, organization = {Academic Press}, address = {New York, NY}, abstract = {Under rangeland conditions most grasses should not.be seeded deeper than 2 cm. Harsh environmental conditions in the surface soil often prevent successful seedling establishment. Army and Hudspeth (1960) and Hudspeth and Taylor (1961) reported that under field conditions in the southern Great Plains sufficient moisture for seedling emergence of grasses planted at the customary shallow depths could not be maintained on bare surface soil except under extremely favorable weather conditions. The average annual precipitation in that area ranges from 36 to 58 cm. Environmental modification, particularly of the moisture and temperature, is imperative to insure greater success in grass establishment. Artificial and natural mulches and land-forming procedures offer increased possibilities for obtaining seedling establishment under difficult environmental conditions.}, keywords = {environmental modification, rangeland, seedling establishment}, url = {/files/bibliography/133.pdf}, author = {C.H. Herbel}, editor = {Youngner, V. and McKell, C.} } @mastersthesis {52354, title = {Effects of watering treatments on emergence of plant species in soil collected from different desert grassland sites}, year = {1971}, note = {//USDA//NONE//}, month = {1971}, pages = {48}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Research reported herein was conducted to determine the emergence of plant species from surface soil collected on black grama (Bouteloua eriopoda) grassland sites in good, fair and poor range condition under various soil moisture levels. The species that emerged and their numbers were compared to the species actually found on the field locations. The potential plants per square meter, represented as viable seed in upper two cms of soil on a black grama range site under the field capacity moisture level, compared with seedlings which emerged in the field locations were, respectively: "fair condition" 993.1 and 103.8; "good condition" 409.7 and 87.4; "poor condition" 687.5 and 147.5. For the conditons of the present experiment, the following conclusions were drawn: 1) The black grama site in good range condition had less plant potential represented as buried seeds, for total numbers of species, than fair and poor conditions; 2) There was no difference between fair and poor range conditions for total plants emerged; 3) Fair condition had more buried grass seed potential than good or poor conditions; 4) Poor condition had more buried seed potential than good condition, but the species were annuals or perennials of low grazing value; 5) When black grama grass dominated a given plant community, emergence in greenhouse of seed potential did not reflect total (seedlings and mature plants) vegetation composition. But when seedling numbers alone were compared to the field location vs. emergence on the greenhouse, a fair idea of seed potential was obtained; 6) Seedlings emerging in the greenhouse reflected the plants of the successsional stage actually sampled in the field locations; 7) The same species emerged when water equivalent to 1-inch in rainfall (925cc) was applied as when the soil was maintained at field capacity; 8) Fewer grass plants emerged when water equivalent to 1/2-inch rainfall (460cc) was applied than with 1-inch of water of field capacity; 9) Water equivalent to 1/4-inch in rainfall (230cc) did not produce significant germination when applied once each four days, but when applied every two days, a significant increase in emergence was observed.}, keywords = {dissertation, dissertations, germination,grassland species, grass, Bouteloua,germination, grass,germination, grassland, germination, seed,Bouteloua, theses, thesis}, author = {Aguirre, Edmundo L.} } @mastersthesis {52377, title = {The effects of soil moisture and soil temperature on decomposition of chitin and chitin containing complexes in soil}, year = {1971}, note = {//NMSU//US-IBP//}, month = {1971}, school = {New Mexico State University}, type = {Ph.D. Dissertation}, address = {Las Cruces, New Mexico}, abstract = {Decomposition studies were conducted using soil collected from the fringe of the playa utilized as the IBP Desert Jornada site. Commercial chitin, larvae casts and a mixture of elytra and thorax cuticle from mature adults of Tenebrio molitor L. were used as soil amendments.... A mathematical model to predict chitin decomposition rates at intermediate moisture-temperature combinations was constructed. A predictive third order regression curve for chitin decomposition at 25 C - 40\% moisture was generated that had a correlation coefficient of 0.9623 with regression curve of actual data obtained from a validation study.}, keywords = {chitin,decomposition, decomposition,chitin, decomposition,soil moisture, decomposition,soil temperature, dissertation, dissertations, theses, thesis}, author = {Wahlquist, Brent T.} } @mastersthesis {52404, title = {Environmental influences on water status in Fouquieria splendens}, year = {1970}, note = {//LOCAL//NONE//}, month = {1970}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {Water stress in Fouquieria splendons was studied. Leaf water potential was used as an index of water stress. Various environmental parameters (precipitation, soil water potential, air water potential, air and soil temperatures) known to affect water stress in other species and possibly contribute to the initiation of dormancy in F. splendons were investigated. Simple linear regression analyses were run, regressing leaf water potential onto each of the environmental parameters which were used as independent variables. It was found that precipitation was the factor that seemed to be significantly affecting leaf water potential. However, it seems that some factor, or factors, other than available moisture induced fall dormancy.}, keywords = {dissertation, dissertations, Fouquieria,water stress, plant,Fouquieria, plant,ocotilla,Fouquieria, theses, thesis}, author = {Wolfe, Helen Gay} } @article {52410, title = {Evaluation of aerial treatments for the control of creosotebush (Larrea tridentata)}, year = {1969}, month = {1969}, pages = {27-28}, institution = {Research Progress Report, Western Society of Weed Science}, abstract = {Creosotebush frequently occurs in almost pure standsin areas of the Southwest where it has invaded. Selective chemical control of creosotebush offers a means for natural revegetation where remnants of perennial grasses remain. This study was initiated to evalute the response of creosotebush to aerial application of materials which had appeared promising in small plot tests.}, keywords = {aerial treatments, creosotebush, Larrea tridentata}, url = {/files/bibliography/112.pdf}, author = {W. L. Gould and C.H. Herbel} } @article {52412, title = {Evaluation of herbicide treatments for the control of creosotebush (Larrea tridentata)}, year = {1969}, month = {1969}, pages = {26-27}, institution = {Research Progress Report, Western Society of Weed Science}, abstract = {Creosote bush is an evergreen xerophyte which has invaded extensive areas of desert rangeland in the Southwestern United States. Much of the infested area at one time was productive grassland, but drought and grazing by livestock has shifted the balance in favor of the brush so many areas are heavily infested with creosote bush and nearly devoid of grass. Control of the creosotebush is necessaryto effect revegetation. Creosote bush sprouts profusely from the crown when the topgrowth is removed mechanically. Satisfactory seeding methods have not been developed for the arid Southwest, so chemical treatments must be used which will selectively remove the brush and leave the grass. Treatments were applied on the Jornada Experimental Range near Las Cruces, New Mexico, from 1961 through 1965 to determine the most effective herbicides and the optimum date of application for the control of creosote bush. Simulated aerial application was made on 1/100 acre plots at 2-week intervals from July through October or November. In one year (1963), treatments were initiated in April. Treatments in 1961 included 2,4-D, 2,4,5-T, 2,4-DP, silvex, 2,3,6-trichlorobenzoic acid and amitrole-T. In 1962, dicamba wasadded to the list of herbicides and in 1963 picloram was added. The herbicide rate at each application date was 1/2 lb/A in 1961 and 1962, 1 lb/A in 1963 and 1 1/2 lb/A in 1964 and 1965, except that picloram was applied at 3/8 lb/A in 1963. On one spray date in 1962, 1963 and 1964, herbicides were applied at three rates to help elucidate the optimum herbicide rate. The dates of maximum toxicity, as determined by evaluating the degree of defoliation 2 years after herbicide application, varied yearly from late July to early November, but generally in a given year all the herbicides caused maximum defoliation on a common date of application. Treatments during September caused the highest degree of defoliation in 3 of the 5 years. Highest levels of defoliation occurred from treatments with dicamba, picloram and 2,3,6-TBA on 3 different dates in 2 of the years. Very little defoliation was obatined from treatments applied before July. This would indicate that creosotebush is most susceptible to herbicides when treated after the summer rainy season has started.}, keywords = {cresotebush, desert rangeland, herbicide treatments, invasion, Larrea tridentata}, url = {/files/bibliography/110.pdf}, author = {W. L. Gould and C.H. Herbel} } @mastersthesis {52419, title = {Energy dynamics and net productivity of annual plants in southern New Mexico}, year = {1969}, note = {//LOCAL//NONE//}, month = {1969}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {Species composition and energy dynamics of annual plants were measured at three elevations between Las Cruces and the Organ Mountains during 1968. Production was measured by randomly selecting plants which were in anthesis and referring to permanent quadrats to record phenology and densities throughout the growing season. Caloric contents were determined for the roots and shoots of each species. Energy measurements varied from 37.45 kcal/m2 at 4400{\textquoteright} in March to 514.62 kcal/m2 at 5000{\textquoteright} in June. The productivity for the growing season was 751.82 kcal/m2 and the average production was 4.08 kcal/m2/day (1.08 g/m2/day) during a 184 day growing period. Productivity varied from one site to another and varied throughout the growing season. Factors which produced this variation were precipitation, topography, and edapic factors.}, keywords = {annual plant, energy dynamics, annual plant, productivity, dissertation, dissertations, theses, thesis}, author = {Hettinger, Loren Robert} } @article {52426, title = {Effects of high temperatures on emergence and initial growth of range plants}, journal = {Agronomy Journal}, volume = {61}, year = {1969}, month = {1969}, pages = {621-624}, abstract = {The daily soil temperatures used in this light chamber study were patterned after observations made under field conditions: 18 to 39C where the surface was sparsely shaded by brush and 18 to 53C where the surface was left bare. The soil moisture was maintained at field capacity. Emergence of sacaton (Sporobolus wrightii Munro), vine mesquite (Panicum obtusum HBK), bush muhly (Muhlenbergia porteri Scribn.) and fourwing saltbush [Atriplex canescens (Pursh) Nutt.] was adversely affected by the high-temperature regime. Survival of all 14 accessions except rhodesgrass (Chloris gayana Kunth), {\textquoteright}Vaughn{\textquoteright} sideoats grama [Bouteloua curtipendula (Michx.) Torr.] and black grama [B. eriopoda (Torr.) Torr.] was reduced by the high-temperature regime. At the close of the 21-day trial, most species had stopped growing or were growing very slowly under the high-temperature regime. The shoot weights for the plants growing in the low-temperature regime averaged nearly twice as much as those growing in the high-temperature regime. There was no significant difference in root weight per seedling between temperature regimes. The root lengths of black grama, {\textquoteright}Vaughn{\textquoteright} sideoats grama, tobosa [Hilaria mutica (Buckl.) Benth.], lehmann lovegrass (Erogrostis lehmanniana Nees) and alkali sacaton [Sporobolus airoides (Torr.) Torr.] were not reduced significantly by the high-temperature regime. The high temperatures were detrimental in one way or another to all species even when moisture was adequate, but black grama and sideoats grama performed satisfactorily.}, keywords = {root length, root weight, shoot height, shoot weight, survival}, url = {/files/bibliography/121.pdf}, author = {R. E. Sosebee and C.H. Herbel} } @mastersthesis {52429, title = {Emergence from soil, germination, water use, and production of russian thistle (Salsola kali L.)}, year = {1969}, note = {//??//NONE//}, month = {1969}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, germination,Salsola, plant,also SEE , plant,russian thistle,Salsola, plant,Salsola, Salsola,phenology, theses, thesis}, author = {Wolde-Yohannis, K.} } @article {52431, title = {Energy requirements of Uta stansburiana}, journal = {Copeia}, volume = {4}, year = {1968}, note = {//LOCAL//NONE//}, month = {1968}, pages = {678-683}, abstract = {

Field data on the type and duration of above ground activity were obtained for a population of Uta stansburiana. These lizards were estimated to spend 2188 hr per year above ground, approximately 1/3 of this time in active movement, and 6652 hr per year in burrows. Air, substratum, and burrow temperatures were recorded weekly throughout the year. Resting and active oxygen comsumption were measured in the laboratory by a modified manometric technique. Resting oxygen consumption increased from a mean of 0.17 cc g/hr at 15 degrees to 0.34 cc g/hr at 35 degrees C. Active oxygen comsuption increased from 0.64 cc g/hr at 15 degrees to 1.1 cc g/hr at 35 degrees C. Oxygen consumption was usesd with field estimates of activity and environmental temperatures to calculate the energy budget for an adult U. stansburiana, 58 KCal/yr. Approximately 0.1\% of the net primary productivity of a creosote bush (Larrea) community was estimated to be dissipated by the U. stansburiana. Thus these lizards play a minor role in the energy transfers in a Larrea community.

}, keywords = {article, articles, behavior, Uta, journal, journals, lizard, physiology, lizard, side-blotched, lizard, Uta, lizard,behavior, reptile, also SEE }, doi = {10.2307/1441833}, url = {files/bibliography/68-Copeia-Whitford.pdf}, author = {Charles E. Alexander and Walter G. Whitford} } @conference {52436, title = {Effect of the esophageal fistula on chemical composition of feeds}, booktitle = {Journal of Animal Science}, volume = {27}, year = {1968}, month = {1968}, pages = {1183}, abstract = {Organic matter recovery of seven feeds collected through esophageal fistulae of three steers varied from 87.5 to 95.2\% and averaged 90.4\%. The seven feeds were alfalfa hay, tobosa hay, 70\% alfalfa-30\% milo pellet, 20\% alfalfa-80\% concentrate mixture, 20\% cottonseed hulls-80\% concentrate mixture, ground milo and cottonseed meal. The fistual samples were significantly higher in ash for all feeds except cottonseed meal, higher in protein for ground milo and higher in A.O.A.C. fiber for alfalfa hay; but, they were lower in ether extract for the alfalfa-milo pellet, alfalfa-concentrate mixture, cottonseed hulls-concentrate mixture and ground milo, and lower in A.O.A.C. fiber for tobosa hay. Fistula samples of grazed forage contained significantly more silica, ash, protein, ether extract, detergent fiber and detergent lignin but less A.O.A.C. fiber than hand-plucked samples obtained from seven pastures of tobosa [Hilaria mutica (Buckl.) Benth.]. Because of relatively high silica content of the samples (8.0\%), chemical composition was compared on a silica-free basis. There were seven pastsure treatments and pasture differences were significant for all constituents except ash. Pasture x method interaction was significant for ash and protein. Detergent fiber was significantly higher than A.O.A.C. fiber for both hand-plucked and fistula samples in all pastures.}, keywords = {chemical composition, esophageal fistula, feeds}, author = {H.E. Kiesling and Nelson, A.B. and C.H. Herbel} } @mastersthesis {52439, title = {Ecotypic variation in seed and seedling characteristics in New Mexico galleta grass}, year = {1968}, note = {//NMSU//NONE//}, month = {1968}, pages = {33}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Ecotypic variation in seed and seedling characteristics of New Mexico galleta grass were studied at the New Mexico Agricultural Experiment Station ranch at Las Cruces, New Mexico. Live clonal material of galleta grass was collected from Fort Stanton, Bernardo, Quemdo, Naschitti, Cuba, Los Lunas and Tucumcari, New Mexico. The material was collected in the fall of 1966 and held in the greenhouse until the spring of 1967. It was then transplanted to study plots located on the ranch.}, keywords = {dissertation, dissertations, grass, ecotypic variation, grass, galleta, seed, galleta grass, theses, thesis}, author = {Law, Lamont Worthen} } @mastersthesis {52459, title = {Energy requirements of the side-blotched lizard (Uta stansburiana)}, year = {1966}, note = {//LOCAL//NONE//}, month = {1966}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {The environmental temperature, oxygen consumption, diel activity, and critical thermal minimum in Uta stansburiana, was studied to estimate the yearly energy requirements for a population of this lizard. There was no significant difference between the critical thermal minimum of lizards acclimated at 15-25 degrees C and 25-35 degrees C. However, a significant difference (P<0.05) was found between groups acclimated to 15 and 35 degrees C. The mean CTMin of lizards acclimated to 15,25, and 35 degrees C was 7.5, 7.8, and 9.6 degrees C respectively. Dawson and Bartholomew (1956); Roberts (1966) found conclusive evidence that acclimation, as measured by oxygen consumption, did not occur in Uta stansburiana. However, in this study Uta were found to acclimate to temperature, at least with respect to the minimum teperature at which coordinate muscular movement is possible. Measurements of resting and active oxygen consumptionwere made on the laboratory at 15,25, and 35 degrees C. The mean oxygen consumption for animals at rest increased from 0.17 cc/gram/hour at 15 degrees C, to 0.34 cc/gram/hour at 35 degrees C, with no significant difference between the 25 and 35 degrees C acclimated groups. Active metabolism increased from 0.64 cc/gram/hour at 15 degrees C, to 1.1 cc/gram/hour/ at 35 degrees C, with no signigicant difference between ther 15 and 25 degrees C acclimated groups. The Q(10) values for resting individuals at 15 to 25 degrees C and 25 to 35 were 1.55 and 1.29 respectively, whereas Q(10) values for active animals at the same temperatures were 1.17 and 1.46 respectively. In order to calculate the yearly energy budget for a population of Uta stansburiana, it was necesssary to estimate the number of hours the lizards spend in active movement, resting above ground, and in burrows. Data for this calculation was obtained by field observation and climatological data for this area. The estimated number of Calories dissipated per year were calculated from the net productivity of Calories per acre per month. Assuming an adult density of 18.4 individuals per acre (Tinkle, McGregor, and Dana 1962) in a Larrea community, a population of Uta stansburiana would dissipate approximately 1053.4 Calories/population/acre/year or 57.2478 Calories/animal/year, assuming that its diet consists of mainly protein material from the consumption of insects. However, to calculate an accurate percentage of the total dissipation of energy derived from their habitat, information reguarding the energy requirement for insects, the animals source of food, is needed, Therefore, without this information, the percentage of primary productivity consumed by a populatoin of Uta stansburiana cannot accurately be determined.}, keywords = {behavior, Uta, dissertation, dissertations, lizard, side-blotched, lizard, Uta, lizard,behavior, lizard,physiology, reptile, also SEE , theses, thesis, Uta, activity, Uta,physiology}, author = {Charles E. Alexander} } @mastersthesis {52475, title = {The effects of soil temperature and moisture on seedling emergence and initial growth}, year = {1966}, note = {//LOCAL//NONE//}, month = {1966}, pages = {61}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The purpose of this study was to determine the actual difference in the effects on seedling emergence and initial growth of two soil temperature regimes observed under field conditions; 70 to 105 F where surface was shaded by brush and 70 to 135 where surface was left bare. In Phase I, there were few significant differences within the attributes measured under the low temperature regime. In the high temperature regime, survival and early growth of vaughn sideoats grama and black grama were outstanding among the 14 species tested. In Phase II, black grama was better able to tolerate the higher soil temperature and moisture stress than boer lovegrass.}, keywords = {dissertation, dissertations, germination, soil moisture, germination, soil temperature, grass,seedlings, theses, thesis}, author = {R. E. Sosebee} } @mastersthesis {52484, title = {Estimated intake and nutritive value of range forage grazed by Hereford and Santa Gertrudis cows}, year = {1965}, note = {//NMSU//NONE//}, month = {1965}, pages = {33}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Organic matter intake and digestibility of range forage by Hereford and Santa Gertrudis cows were studied in the desert grassland area of southern New Mexico using lignin as an indicator over a 3-yr. period. Feces were collected monthly from two cows of each breed for a 4-hr. and 6-hr. period using fecal collection bags and harnesses. The use of the lignin content of hand-plucked forage samples provided better estimates of organic matter intake than did the lignin content of forage samples collected by the rumen evacuation method. When using hand-plucked forage samples the estimated intake of Herefords was slightly above the dry matter requirements but the intake for Santa Gertrudis was below requirements. Forage intake estimates based on rumen samples were not satisfactory for either breed. Forage sampling methods were significantly (p<.01) different for the nutritional components: organic matter, protein, fiber and lignin. Hand-plucked samples were highest in organic matter but rumen samples contained higher levels of protein, fiber and lignin. Chemical composition was not significantly different between breeds. Within breeds, monthly variation of protein content was not consistent, thus a significant (P<.01) breed x months interactions. For protein the breed x method interaction was significant (P<.05) but there were no monthly differences within hand-plucked or rumen samples.}, keywords = {cattle, food habits, cattle, management, cattle, nutrition, cattle, range forage, dissertation, dissertations, food habits, cattle, theses, thesis}, author = {Hill, Kenneth R.} } @mastersthesis {52487, title = {Estimates of inbreeding, sex, age of dam and year effects on beef calf performance}, year = {1965}, note = {//?///NONE//}, month = {1965}, pages = {50}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle, breeding, cattle,productivity, dissertation, dissertations, theses, thesis}, author = {Moore, John Verne} } @mastersthesis {52495, title = {The effect of plane of nutrition upon the levels of certain blood constituents in weaning hereford heifers in southern New Mexico}, year = {1964}, note = {//??//NONE//}, month = {1964}, pages = {102}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle, nutrition, cattle, physiology, cattle,blood constituents, dissertation, dissertations, theses, thesis}, author = {Mufarrih, Muhamed E.} } @mastersthesis {52502, title = {Estimating grass herbage production on desert plains grassland range}, year = {1963}, note = {//NMSU//NONE//}, month = {1963}, pages = {37}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, grass, productivity, model, grass production, productivity, grass, theses, thesis}, author = {E. Parker} } @mastersthesis {52516, title = {The effects of aqueous extracts of creosotebush on germination and growth of some desert plains grassland plants}, year = {1960}, note = {//NMSU//NONE//}, month = {1960}, pages = {55}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The purpose of this study was to determine if the creosotebush contains an inhibitor which may be a contributing factor to the invasion of creosotebush on grassland. Aqueous extracts from creosotebush plant material, of relatively high concentration, significantly reduced the germination of black grama caryopses, prevented the development of radicles and significantly reduced plumule growth of both black grama and bush muhly. The extract was not inhibitory to germination or seedling growth of creosotebush.}, keywords = {black grama, Bouteloua, germination, bush muhly, dissertation, dissertations, germination success, Larrea, extract, Larrea, germination, Muhlenbergia, germination, seed, germination, Larrea extract, theses, thesis}, author = {Knipe, Oren D.} } @article {52515, title = {The effects of limited moisture on germination and initial growth of six grass species}, journal = {Journal of Range Management}, volume = {13}, number = {6}, year = {1960}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {November 1, 1960}, pages = {297-302}, abstract = {Vast areas of rangeland in the Southwestern states which were formerly dominated by perennial grasses are now badly in need of revegetation. This condition presents a problem in the selection of grass species for reseeding. Growing-season precipitation results from convectional storms and is erratic in distribution both as to time and location. This, coupled with the high evaporation rate from sparsely vegetated loamy sand and sandy loam soils characteristic of much of the region, makes for low effectiveness of precipitation. Therefore, species selected for reseeding should be those which are best adapted to germination and survival under conditions of limited moisture. The objectives of this study were to determine the effect of different degrees of moisture stress on time required for germination, total germination and initial seedling growth of six warm season grass species.}, keywords = {germination, grass species, growth, limited moisture, reseeding, revegetation}, url = {/files/bibliography/082.pdf}, author = {Knipe, D. and C.H. Herbel} } @mastersthesis {52527, title = {Effects of various environmental factors on the occurrence of cancer eye in Hereford cattle}, year = {1956}, note = {//??//NONE//}, month = {1956}, pages = {18}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle,disease, cancer eye, disease, cancer eye, dissertation, dissertations, theses, thesis}, author = {Harrington, F. Eugene} } @mastersthesis {52528, title = {The effects of mild inbreeding on weaning weight and grade of Hereford cattle}, year = {1954}, note = {//NMSU//NONE//}, month = {1954}, pages = {29}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The effects of mild inbreeding on weaning weight and grade of range Hereford calves were analyzed. Partial regression coefficients were estimated for certain factors which effect weaning weight and grade. The factors which could be studied and which were assumed to affect weaning weight and grade were age of calf in days, sex, size of dam at 18 months, inbreeding of the calf and inbreeding of the dam. The study included calves sired by 34 bulls over a 14 year period.}, keywords = {cattle, inbreeding, dissertation, dissertations, genetics, cattle inbreeding, history, cattle breeding, theses, thesis}, author = {McCleery, Neil B.} } @article {52540, title = {Effect of Rodents, Rabbits, and Cattle on Two Vegetation Types in Semidesert Range Land}, number = {Bulletin 353}, year = {1950}, month = {January 1950}, pages = {24}, institution = {New Mexico Agricultural Experimental Station}, address = {Las Cruces}, keywords = {bulletin, cattle, rabbits, rangeland, rodents, vegetation}, url = {/files/bibliography/103.pdf}, author = {Norris, J. J.} } @article {52541, title = {Effects of rodents, rabbits, and cattle on two vegetation types in semi-desert range land}, year = {1950}, note = {//??//NONE//}, month = {1950}, institution = {New Mexico Agricultural Experiment Station}, address = {Las Cruces, New Mexico}, keywords = {book, books, cattle,effect on vegetation, chapter, chapters, rabbit,effect on vegetation, report, reports, rodent,effect on vegetation}, isbn = {Bulletin 353}, author = {Norris, J. J.} } @article {52552, title = {Effect of Water-Retaining and Water-Spreading Structures in Revegetating Semidesert Range Land}, volume = {341}, number = {341}, year = {1947}, institution = {New Mexico College of A. \& M.A.}, address = {State College, NM}, isbn = {Bulletin 341}, url = {/files/bibliography/044.pdf}, author = {Valentine, K. A.} } @article {52559, title = {The effect of sex on weaning weight of range calves}, journal = {Journal of Animal Science}, volume = {4}, year = {1945}, note = {//??//NONE//(New Mexico Agr. Exp. Station Journal Article 31)//}, month = {1945}, pages = {15-19}, keywords = {article, articles, cattle, productivity, journal, journals}, author = {Koger, M. and Knox, J. H.} } @article {52585, title = {Electric fence effective on range}, journal = {The Hereford Journal}, volume = {29}, number = {17}, year = {1939}, month = {January 1, 1939}, pages = {54}, abstract = {Preliminary results in the range use of one-wire electric fences on the Jornada Experimental Range of the Southwestern Forest and Range Experiment Station indicate that such fences have possibilities as a cheap and effective means of controlling livestock on the range. In August 1938, 3.5 miles of one-wire fence was constructed around one of the large tobosa flats on the Jornada for the purpose of holding cattle on the tobosa summer feed and, at the same time, protecting the surrounding grama grass from heavy use during the growing season. Following the heavy rains in July, the tobosa grass was green and succulent and, when the fence was built, the soil was very damp. However, before the electrical unit ordered arrived, the soil had dried out thoroughly and the first results on this dry soil were disappointing. About 140 yearling heifers were placed inside the enclosure and, at first, they passed back and forth under the wire freely. After about 3 days, a light shower fell wetting the ground to a depth of about on-half inch and, following this there was no more passing back and forth under or even approaching the charged wire.}, keywords = {controlling livestock, electric fences, Jornada Experimental Range, range}, url = {/files/bibliography/045.pdf}, author = {F.N. Ares} } @article {52588, title = {The effect of intensity and frequency of clipping on density and yield of black grama and tobosa grass}, year = {1939}, month = {May 1939}, pages = {32 }, publisher = {U.S. Government Printing Office}, abstract = {In spite of any difficulties pertaining to finance, economics and periodically adverse climatic conditions that may beset the stockman of the semidesert grasslands, there probably never will come a time when cattle economically produced by conservative year-long grazing on the native forage will cease to be generally profitable. However, if this source of feed is to be perpetually enjoyed, certain fundamental principles of range conservation that give due consideration to the preservation of the main forage plants are required to be observed in grazing use. This is especially true in the Southwest where one of the most extensive grass areas, comprising some 14 million acres of semidesert grasslands, has developed under an average rainfall of approximately 10 inches annually. These lands, which are restricted to the law hills, valleys, and mesas lying at elevations below the pinon-juniper type in western Texas, southern New Mexico, and southeastern Arizona, are conceded to be chiefly valuable for the grazing of domestic livestock, principally cattle.}, keywords = {black grama, frequency, government publication, intensity of clipping, tobosa grass, yield}, url = {/files/bibliography/048.pdf}, author = {Canfield, R.H.} }