@proceedings {JRN55365, title = {Precision grazing: State of the science and opportunity for user feedback on new technologies}, year = {2022}, month = {3/29/2028}, abstract = {Precision farming technologies are an emerging management platform aimed at digitizing crop and animal production practices to enable detection and mediation of real-time environmental and welfare concerns and to equip producers with affordable, accurate, and easy-to-use tools to improve production sustainability. The goal of this symposium is to highlight current state-of-the-art precision grazing and digital ranching tools, techniques, and platforms under study and in development for application on extensive rangelands. The session will be broadly targeted toward scientists, government agencies, and producers, all of whom are presumed to benefit from precision grazing technologies. The morning session of the Precision Grazing symposium will feature a suite of rangeland scientists investigating various precision grazing tools including virtual fencing, tri-axial accelerometers, and grazing detection instruments, as well as producer outlooks on digital ranching necessities. The afternoon session will feature work conducted by the Sustainable Southwest Beef Coordinated Agricultural Project which is aimed at developing an integrated precision grazing system and dashboard that can track cattle and sheep welfare and geolocation, body condition scores, and other ranch infrastructure in near real time in various production systems.}, keywords = {feedback, new technologies, opportunity, Precision grazing, science, state}, author = {Matthew M. McIntosh and S. Spiegal and Skye Aney and Jean Steiner} } @article {JRN55319, title = {Poultry manureshed management: Opportunities and challenges for a vertically integrated industry}, journal = {Journal of Environmental Quality}, year = {2021}, month = {7/26/2021}, pages = {1-12}, abstract = {Manureshed management seeks to address systemic imbalances in nutrient distributions at scales beyond the farmgate and potentially across county and state boundaries. The U.S. poultry industry, which includes broilers, layers, pullets, and turkeys, has many characteristics that are compatible with achieving a vision of manureshed management, including a history of engaging in local and regional programs to better distribute manure resources. Despite widespread vertical integration that supports large-scale strategic decision making and dry manures that favor off-farm transport, there are still many challenges to poultry manureshed management that require engaging stakeholders other than just the poultry industry. Analysis of county-level nutrient budgets highlights the industry{\textquoteright}s {\textquotedblleft}mega-manureshed,{\textquotedblright} extending from the Mid-Atlantic, across the southeast, and into northwest Arkansas, Oklahoma, and Texas. The analysis also identifies areas with legacy nutrient build-up that are still present today. Implementing manureshed management in the U.S. poultry industry requires comprehensive consideration of manure treatment technologies, alternative uses such as bioenergy production, market development for treated manure products, transport of manure nutrients from source to sink areas, and manure brokering programs that promote manure nutrient distribution. Fortunately, past and present evolution and innovation within the industry places it as a likely leader of the manureshed vision.}, keywords = {Poultry manureshed management, vertically integrated industry}, doi = {10.1002/jeq2.20273}, url = {files/bibliography/21-033.pdf}, author = {Ray Bryant and Dinku Endale and S. Spiegal and Colton K Flynn and Robert J. Meinen and Michael Cavigelli and Peter J. A. Kleinman} } @article {JRN55337, title = {Predicting the geographic range of an invasive livestock disease across the contiguous USA under current and future climate conditions}, journal = {Climate}, volume = {9}, year = {2021}, month = {10/29/2021}, pages = {159}, abstract = {Vesicular stomatitis (VS) is the most common vesicular livestock disease in North America. Transmitted by direct contact and by several biting insect species, this disease results in quarantines and animal movement restrictions in horses, cattle and swine. As changes in climate drive shifts in geographic distributions of vectors and the viruses they transmit, there is considerable need to improve understanding of relationships among environmental drivers and patterns of disease occurrence. Multidisciplinary approaches integrating pathology, ecology, climatology, and biogeophysics are increasingly relied upon to disentangle complex relationships governing disease. We used a big data model integration approach combined with machine learning to estimate the potential geographic range of VS across the continental United States (CONUS) under long-term mean climate conditions over the past 30 years. The current extent of VS is confined to the western portion of the US and is related to summer and winter precipitation, winter maximum temperature, elevation, fall vegetation biomass, horse density, and proximity to water. Comparison with a climate-only model illustrates the importance of current processes-based parameters and identifies regions where uncertainty is likely to be greatest if mechanistic processes change. We then forecast shifts in the range of VS using climate change projections selected from CMIP5 climate models that most realistically simulate seasonal temperature and precipitation. Climate change scenarios that altered climatic conditions resulted in greater changes to potential range of VS, generally had non-uniform impacts in core areas of the current potential range of VS and expanded the range north and east. We expect that the heterogeneous impacts of climate change across the CONUS will be exacerbated with additional changes in land use and land cover affecting biodiversity and hydrological cycles that are connected to the ecology of insect vectors involved in VS transmission. }, keywords = {big data; machine learning; vesicular stomatitis; land use; macrosystems; climate change; MaxEnt; livestock epidemiology; climate impact assessment}, doi = {10.3390/cli9110159 }, url = {files/bibliography/21-049.pdf}, author = {N. Dylan Burruss and Luis L Rodriguez and Barbara Drolet and Kerrie Geil and Angela Pelzel-McCluskey and Lee W Cohnstaedt and J. D. Derner and Debra C. Peters} } @article {JRN55341, title = {Parameterizing an aeolian erosion (AERO) model for rangelands}, journal = {Aeolian Research}, volume = {54}, year = {2021}, month = {12/13/2021}, chapter = {100769}, abstract = {Aeolian processes are fundamental to arid and semi-arid ecosystems, but modeling approaches are poorly developed for assessing impacts of management and environmental change on sediment transport rates over meaningful spatial and temporal scales. For model estimates to provide value, estimates of sediment flux that encapsulate intra- and inter-annual and spatial variability are needed. Further, it is important to quantify and communicate transparent estimates of model uncertainty to users. Here, we present a wind erosion and dust emission model parameterized for rangelands using a Generalized Likelihood Uncertainty Estimation framework. Modeled horizontal sediment flux was calibrated using data from five diverse grassland and shrubland sites from the USDA National Wind Erosion Research Network. Observations of wind speed, vegetation height, length of gaps between vegetation, and percent bare ground were used as model inputs. Horizontal sediment flux estimates from 10,000 independently selected parameter sets were compared to flux observations from 44 \~{} month-long collection periods to calculate a likelihood measure for each model. Results show good agreement for individual sampling periods across sites with few observations falling outside prediction bounds and a one-to-one relationship between median predictions and observations. Additionally, combined distributions of sediment flux estimates from all sample periods for a given site closely approximated the probability of observing a given flux at that site. These results suggest AERO effectively represents temporal variability in aeolian transport rates at rangeland sites and provides robust assessments suitable for assessing land health and better predicting changes in air quality and the impacts of land management activities.}, keywords = {aeolian, assessment, dust emission, indicators, land management, monitoring, wind erosion}, doi = {10.1016/j.aeolia.2021.100769}, url = {files/bibliography/21-052.pdf}, author = {Brandon Edwards and Nicholas Webb and Magda Galloza and Justin Van Zee and Ericha Courtright and Brad Cooper and Loretta Metz and Jeffrey E. Herrick and Gregory S. Okin and Danielle Duni and John Tatarko and Negussie Tedela and Daniel N. Moriasi and Beth Newingham and Frederick B. Pierson and David P. Toledo and Scott Van Pelt} } @conference {JRN55425, title = {Participatory research and co-production of knowledge: Building on a century of Jornada experience to expand LTAR outcomes and impacts}, booktitle = {LTAR Annual Meeting}, year = {2021}, abstract = {The co-production of knowledge with stakeholders is a unique strength of the Agricultural Research Service. The objective of this poster is to share examples of how co-production has been successfully applied to achieve four very different sets of objectives with national to global impact: (1) developing standardized rangeland indicators and monitoring methods; (2) developing interpretive tools; (3) identifying research gaps and needs for tools and new indicators (e.g., AERO, phenology) to inform conservation planning; and (4) building understanding of management technologies and systems to meet stakeholder land use goals. Collaborative research examples include work with the Malpai Borderlands Group, the BLM{\textquoteright}s {\textquotedblleft}Restore New Mexico{\textquotedblright} program, the development and implementation of BLM AIM and NRCS NRI national inventory and monitoring programs, NRCS CEAP-Grazing Lands model development (AERO; RHEM) and data processing (Landscape Data Commons) for effects assessments of NRCS conservation practices, the Sustainable Southwest Beef Coordinated Agricultural Project, and the development of LandPKS and EDIT. Our approach to co-production is iterative and results from a 25+ year series of diverse engagement approaches (trainings, working groups, day-to-day involvement), which has led to directly applicable research and management tools. Current LTAR efforts, including the Jornada Common Experiment and those of the LTAR Rangeland Soil Erosion, Wind Erosion, Phenology, and Indicators Working Groups, provide opportunities to expand these long-term participatory research and co-production efforts to improve and extend LTAR research impacts. This poster illustrates lessons learned from the Jornada experience and highlights opportunities for broader collaboration across the LTAR network.}, keywords = {building, century, co-production, impacts, Jornada, Long-Term Agricultural Research outcomes, LTAR, Participatory, research}, author = {Sarah McCord and Brandon T Bestelmeyer and Dawn M. Browning and Laura M. Burkett and Brandon Edwards and Jeffrey E. Herrick and Emily Kachergis and Nika Lepak and Leticia Lister and Loretta Metz and Terri Schulz and S. Spiegal and Nicholas Webb} } @article {JRN55283, title = {Provoking a Cultural Shift in Data Quality}, journal = {BioScience}, year = {2021}, month = {March 31, 2021}, abstract = {Ecological studies require quality data to describe the nature of ecological processes and to advance understanding of ecosystem change. Increasing access to big data has magnified both the burden and the complexity of ensuring quality data. The costs of errors in ecology include low use of data, increased time spent cleaning data, and poor reproducibility that can result in a misunderstanding of ecosystem processes and dynamics, all of which can erode the efficacy of and trust in ecological research. Although conceptual and technological advances have improved ecological data access and management, a cultural shift is needed to embed data quality as a cultural practice. We present a comprehensive data quality framework to evoke this cultural shift. The data quality framework flexibly supports different collaboration models, supports all types of ecological data, and can be used to describe data quality within both short- and long-term ecological studies}, keywords = {Cultural shift, data quality, ecological, ecosystem}, doi = {10.1093/biosci/biab020}, url = {files/bibliography/21-017.pdf}, author = {Sarah McCord and Nicholas Webb and Justin Van Zee and Sarah Burnett and Erica M. Christensen and Ericha Courtright and C. Laney and Lunch, Claire and Connie J. Maxwell and Jason W. Karl and A. L. Slaughter and Nelson Stauffer and Craig Tweedie} } @article {JRN55410, title = {PS3: The Pheno-Synthesis software suite for integration and analysis of multi-scale, multi-platform phenological data}, journal = {Ecological Informatics}, volume = {65}, year = {2021}, month = {11/2021}, pages = {101400}, abstract = {Phenology is the study of recurring plant and animal life-cycle stages which can be observed across spatial and temporal scales that span orders of magnitude (e.g., organisms to landscapes). The variety of scales at which phenological processes operate is reflected in the range of methods for collecting phenologically relevant data, and the programs focused on these collections. Consideration of the scale at which phenological observations are made, and the platform used for observation, is critical for the interpretation of phenological data and the application of these data to both research questions and land management objectives. However, there is currently little capacity to facilitate access, integration and analysis of cross-scale, multi-platform phenological data. This paper reports on a new suite of software and analysis tools {\textendash} the {\textquotedblleft}Pheno-Synthesis Software Suite,{\textquotedblright} or PS3 {\textendash} to facilitate integration and analysis of phenological and ancillary data, enabling investigation and interpretation of phenological processes at scales ranging from organisms to landscapes and from days to decades. We use PS3 to investigate phenological processes in a semi-aride, mixed shrub-grass ecosystem, and find that the apparent importance of seasonal precipitation to vegetation activity (i.e., {\textquotedblleft}greenness{\textquotedblright}) is affected by the scale and platform of observation. We end by describing potential applications of PS3 to phenological modeling and forecasting, understanding patterns and drivers of phenological activity in real-world ecosystems, and supporting agricultural and natural resource management and decision-making.}, keywords = {Hierarchical modeling, landsat, MODIS, National Ecological Observatory Network, PhenoCam, phenology, remote sensing, USA National Phenology Network}, doi = {10.1016/j.ecoinf.2021.101400}, url = {files/bibliography/21-063.pdf}, author = {Jeffrey T. Morisette and Katharyn A. Duffy and Jake F. Weltzin and Dawn M. Browning and R. Lee Marsh and Aaron M. Friesz and Luke J. Zachmann and Kyle D. Enns and Vincent A. Landau and Katharine L.Gerst and Theresa Crimmins and Katherine D. Jones and Tony Chang and Brian W. Miller and Thomas K. Maiersperger and Andrew D. Richardson} } @proceedings {JRN55351, title = {Performance of Lora-WAN sensors for precision livestock tracking and biosensing applications}, year = {2021}, month = {11/2021}, edition = {Nairobi, Kenya}, abstract = {This study investigated the integration of Long Range Wide Area Network (LoRa WAN) communication technology and sensors for use as Internet of Things (IoT) platform for Precision Livestock-Farming (PLF) applications. The research was conducted at New Mexico State University{\textquoteright}s Clayton Livestock Research Centre. The functionality of LoRA WAN communication technology and performance of LoRa WAN motion and GPS sensors were tested using static sensors that were placed either, a) outdoors and at incremental distances from the LoRa WAN gateway antenna (Field, n=6), or b) housed indoors and close to the same LoRa WAN gateway antenna (Indoor, n=5). Accelerometer data, reported as motion intensity index, and GPS location were acquired, transmitted and logged at 1 and 15 minute intervals, respectively. We evaluated the tracker{\textquoteright}s GPS accuracy (GPSBias as the euclidean distance between the actual and projected tracker location) and variables associated with the tracker{\textquoteright}s data transmission capabilities. The results indicate that field trackers had a greater accuracy for remote sensing of GPS locations compared to indoor trackers facing increasing communication interference to acquire satellite signals (GPSBias; 5.20 vs. 17.76 m; P<0.01). Overall, the trackers and deployments appeared to have a comparable GPS accuracy to other tracking devices and systems available in the market. The total data packets that were successfully transmitted were similar between the indoor and field trackers, but the number of data packets that were processed varied between the two deployments (P=0.02). Due to the static deployment of indoor and field trackers, activity data was almost non-existent for most devices. However, same trackers embedded on collars that were mounted on mature cattle showed clear diurnal patterns consistent with time budgets exerted by grazing cattle. The pilot testing of GPS and accelerometer sensors using LoRa WAN technology revealed reasonable sensor sensitivity and reliability for integration in PLF platforms.}, author = {S. Nyamuryekung{\textquoteright}e and Andr{\'e}s F. Cibils and Richard E. Estell and M. Funk and Matthew M. McIntosh and Andrew Cox and S. A. Utsumi and Huiping Cao and LE Boucheron and Qixu Gong and H. Chen and S. Spiegal and G. Duff and V. Gouvea and Carolina Brandani} } @article {JRN55313, title = {Plant species richness in multiyear wet and dry periods in the Chihuahuan Desert}, journal = {Climate}, volume = {9}, year = {2021}, month = {8/13/2021}, pages = {130}, abstract = {In drylands, most studies of extreme precipitation events examine effects of individual years or short-term events, yet multiyear periods (>3 y) are expected to have larger impacts on ecosystem dynamics. Our goal was to take advantage of a sequence of multiple long-term (4-y) periods (dry, wet, average) that occurred naturally within a 26-y time frame to examine responses of plant species richness to extreme rainfall in grasslands and shrublands of the Chihuahuan Desert. Our hypothesis was that richness would be related to rainfall amount, and similar in periods with similar amounts of rainfall. Breakpoint analyses of water-year precipitation showed five sequential periods (1993{\textendash}2018): AVG1 (mean = 22 cm/y), DRY1 (mean = 18 cm/y), WET (mean = 30 cm/y), DRY2 (mean = 18 cm/y), and AVG2 (mean = 24 cm/y). Detailed analyses revealed changes in daily and seasonal metrics of precipitation over the course of the study: the amount of nongrowing season precipitation decreased since 1993, and summer growing season precipitation increased through time with a corresponding increase in frequency of extreme rainfall events. This increase in summer rainfall could explain the general loss in C3 species after the wet period at most locations through time. Total species richness in the wet period was among the highest in the five periods, with the deepest average storm depth in the summer and the fewest long duration (>45 day) dry intervals across all seasons. For other species-ecosystem combinations, two richness patterns were observed. Compared to AVG2, AVG1 had lower water-year precipitation yet more C3 species in upland grasslands, creosotebush, and mesquite shrublands, and more C4 perennial grasses in tarbush shrublands. AVG1 also had larger amounts of rainfall and more large storms in fall and spring with higher mean depths of storm and lower mean dry-day interval compared with AVG2. While DRY1 and DRY2 had the same amount of precipitation, DRY2 had more C4 species than DRY1 in creosote bush shrublands, and DRY1 had more C3 species than DRY2 in upland grasslands. Most differences in rainfall between these periods occurred in the summer. Legacy effects were observed for C3 species in upland grasslands where no significant change in richness occurred from DRY1 to WET compared with a 41\% loss of species from the WET to DRY2 period. The opposite asymmetry pattern was found for C4 subdominant species in creosote bush and mesquite shrublands, where an increase in richness occurred from DRY1 to WET followed by no change in richness from WET to DRY2. Our results show that understanding plant biodiversity of Chihuahuan Desert landscapes as precipitation continues to change will require daily and seasonal metrics of rainfall within a wet-dry period paradigm, as well as a consideration of species traits (photosynthetic pathways, lifespan, morphologies). Understanding these relationships can provide insights into predicting species-level dynamics in drylands under a changing climate.}, keywords = {climate change; extreme events; breakpoint analysis; Chihuahuan Desert; black grama grasslands; mesquite shrublands; precipitation characteristics; multiyear periods; legacies}, doi = {10.3390/cli9080130}, url = {files/bibliography/21-030.pdf}, author = {Debra C. Peters and Heather Savoy and Susan Stillman and Haitao Huang and Amy R. Hudson and O. E. Sala and Enrique Vivoni} } @article {JRN55205, title = {Phenological changes in the nutritive value of honey mesquite leaves, pods, and flowers in the Chihuahuan Desert}, journal = {Agrosystems, Geosciences \& Environment}, volume = {3}, year = {2020}, month = {04/2020}, chapter = {e20026}, abstract = {Honey mesquite [Prosopis glandulosa (Torr.) glandulosa] is a potential foraging resource in southwestern United States rangelands and in other semi-arid rangelands. Yet, intake by ruminants is limited. We conducted an in vitro digestion experiment to assess phenological changes in nutrient value and relative digestibility of honey mesquite leaves, pods, and flowers throughout the 2012 growing season. Crude protein (CP) content of leaves decreased (P < .001) during the year, while acid detergent fiber (ADF) and neutral detergent fiber (NDF) increased (P < .05). Crude protein content of pods decreased (P = .009) over time, but we did not detect (P > .10) any phenological changes in ADF or NDF levels during the study. A cubic response was observed with in vitro gas production and Julian date for both leaves and pods (P <= .01). Gas production from leaves collected in spring and early summer were lower than during late summer and early fall. Gas product1ion and nutrient content values suggest that concentration of secondary compounds of mesquite leaves may decrease in late summer. Gas production values of mesquite leaves were lowest in early and mid-summer when CP levels were high and fiber levels were low. Mesquite flowers and pods can be valuable forage resources for cattle. Although mesquite leaves contain nutrients, secondary compounds likely limit intake, especially in late spring and early summer when the CP in mesquite leaves would be most beneficial because quality of herbaceous forages in southwestern United States rangelands at that time is usually low.}, doi = {10.1002/agg2.20026}, url = {bibliography/20-014.pdf}, author = {Piedad Mayagoitia and C. Donovan Bailey and Richard E. Estell} } @article {JRN55267, title = {A phenotypic characterization of Rar{\'a}muri Criollo cattle introduced into the southwestern United States}, journal = {Archivos Latinoamericanos De Produccion Animal}, volume = {28}, year = {2020}, month = {11/5/2020}, pages = {111-119}, abstract = {Our objective was to describe key phenotypic characteristics of a population of Rar{\'a}muri Criollo (RC) cattle introduced from the Copper Canyon of Chihuahua, M{\'e}xico into the Southwestern United States almost two decades ago. We recorded 26 phenotypic traits of 37 RC individuals including mature cows, first--calf heifers, and mature bulls raised at the USDA--ARS Jornada Experimental Range in southern New Mexico. This herd of RC cattle exhibited intermediate body sizes (390 kg) compared to the smaller Corriente (300 kg) and larger Texas Longhorn (400 kg) and Florida Cracker cattle (400 kg). Coat colors were similar to those described for other Criollo biotypes but horn shape and size of RC appear to be different than that of other US--based Criollo breeds. Though smaller than commercial beef breeds, RC cattle appear to be well -matched to the Southwestern US environments as evidenced by previous studies that evaluated their grazing behavior, weight gains, and carcass quality. Rar{\'a}muri Criollo cattle are a genetic resource whose conservation could be critically important for climate change adaptation of ranches in the desert Southwest. https://ojs.alpa.uy/index.php/ojs_files/article/view/2832}, keywords = {beef cattle, climate change, genetic conservation, heritage breed}, url = {files/bibliography/21-003.pdf}, author = {Matthew M. McIntosh and Amy L. Gonzalez and Andr{\'e}s F. Cibils and Richard E. Estell and S. Nyamuryekung{\textquoteright}e and A.F.A. Rodriguez and S. Spiegal} } @conference {JRN55250, title = {The pipeline of phenological data in large scale automated forecasts}, booktitle = {Ecological Society of America}, year = {2020}, month = {08/2020}, address = {Virtual Conference}, abstract = {I built a near-term phenology-forecasting system which predicts the timing of budburst, flowers, ripe fruit, and fall colors for 78 species up to 6 months in advance and is updated every four days. Here I describe the flow of phenological data from raw observations to model output and presentation, addressing the challenges of continuous large data integration. Using open source tools and formats allows for robust workflows and pipelines, where adding new species, tracking model progression, and integrating the newest data is streamlined. Outlining these best practices will allow for the rapid development of robust forecasting tools in ecology. Poster $\#$82199}, author = {Shawn D. Taylor} } @article {JRN55095, title = {Plant phenology: Taking the pulse of rangelands}, journal = {Rangelands}, volume = {41}, year = {2019}, month = {06/2019}, pages = {129-134}, chapter = {129}, abstract = {Plant phenology{\textemdash}the timing of seasonal life cycle events{\textemdash}is a primary control on ecosystem productivity and an integrative indicator of species{\textquoteright} responses to the environment. Plant phenology data can be used to design better management systems by adjusting the timing of grazing, fire and other disturbances relative to the growth stage of key species and in planning restoration activities such as herbicide applications or targeted grazing. Repeated observations needed to understand phenology can be collected at various spatial scales with a variety of methods from field-based observations of individual plants to broad-scale observations of landscape {\textquotedblleft}greenness{\textquotedblright} from satellite imagery. Digital cameras mounted on towers (phenocams) provide a more cost-effective way to collect data to capture vegetation {\textquotedblleft}greenness.{\textquotedblright} Phenocam greenness values are used to generate plant canopy- and community-level metrics in real-time for a fraction of the cost of on-the-ground field observations. Phenocam greenness metrics also serve to link plant- or community-scale phenology observations collected in the field with those from satellite remote sensing and can reveal the plant species or functional groups contributing to satellite NDVI. Phenocam image time series also help interpret rangeland monitoring data by placing data in the context of inter- and intra-annual variability.}, keywords = {grasslands, invasive species, management tools, monitoring, phenocams, plant phenology}, doi = {doi.org/10.1016/j.rala.2019.02.001}, url = {files/bibliography/19-011.pdf}, author = {Dawn M. Browning and K. A. Snyder and Jeffrey E. Herrick} } @article {JRN55047, title = {Prioritizing land for investments based on short- and long-term land potential and degradation risk: A strategic approach}, journal = {Environmental Science and Policy}, volume = {96}, year = {2019}, month = {03/2019}, pages = {52-58}, chapter = {52}, abstract = {

The response hierarchy of {\textquotedblleft}Avoid \> reduce \> reverse{\textquotedblright} is widely accepted as the best strategy for prioritizing actions designed to address land degradation at hectare to national scales. This hierarchy is based on the assumption that the economic return on investment (ROI) will usually be higher for actions that help avoid degradation than for those required to restore already degraded land. While a useful first step, the hierarchy fails to account for how differences in land potential, defined as its potential to sustainably generate ecosystem services, may affect the ROI of actions at each level of the response hierarchy. The objective of this paper is to present a strategy for improving ROI at the landscape scale and above by systematically applying a more holistic understanding of land potential to the identification and prioritization of land investments. This objective is addressed in three sections. The first section explains how the potential short- and long-term resistance and resilience of the land can be used together with its potential productivity to prioritize actions designed to avoid, reduce and reverse degradation. In the second section we explain how this prioritization can be further optimized based on an understanding of degradation risk as indicated by the land{\textquoteright}s potential to generate relatively high short-term profits under management systems that are likely to increase degradation, or result in degradation of restored land. This potential, and land managers{\textquoteright} perception of it, depend on a wide variety of factors including markets, infrastructure, and access to technology. Together these first two sections provide a framework for increasing ROI, while reducing the risk of failure at hectare to national scales. In the final section we briefly describe the Land-Potential Knowledge System (LandPKS), a modular mobile app that makes it possible for virtually anyone with a smartphone to make the land potential determinations necessary to apply the framework described in the first two sections.

}, keywords = {economics, investment, land degradation, land evaluation, land restoration, return on investment}, doi = {doi.org/10.1016/j.envsci.2019.03.001}, url = {files/bibliography/19-003.pdf}, author = {Jeffrey E. Herrick and J. Neff and Amy Quandt and S. W. Salley and Jonathan Maynard and Amy Ganguli and Brandon T Bestelmeyer} } @conference {JRN54941, title = {Phenocams bridge the gap between field and satellite observations: Applications from agroecosystems}, booktitle = {US-International Association for Landscape Ecology}, year = {2018}, month = {04/2018}, address = {Chicago, Illinois}, abstract = {

Agro-ecosystems represent a gap in national research networks established to address ecological questions that site-level research cannot address. The Long-Term Agroecosystem Research (LTAR) network established by the U.S.D.A. Agriculture Research Service is intended to fill this gap. In this study, we combine data from two LTAR network sites in the arid southwestern U.S. spanning 18 site-years to evaluate relationships between greenness index values derived from near-surface phenocams (GCC) and MODIS satellite imagery (NDVI) with measures of ecosystem productivity. Two core data sets for sites in the LTAR network are aboveground net primary production (ANPP) estimated in the field and gross primary production (GPP) modeled from eddy covariance flux towers. We explore relationships between remotely-derived greenness using camera GCC and MODIS NDVI indices and ANPP and GPP from 2013 to 2016. We used ANPP at three camera sites on the Jornada Experimental Range (JER) in southern New Mexico and GPP at two camera sites at the Walnut Gulch Experimental Watershed (WGEW) in southern Arizona. We calculated pairwise Pearson correlations between growing season integrals of GPP derived from CO2 flux measurements and remotely-sensed indicators (camera GCC and NDVI) at the two WGEW sites. At JER, we calculated correlations between ANPP and growing season integrals of GCC and NDVI. Our analysis showcases methods for comparing ANPP computed annually and GPP estimated daily with time series GCC and NDVI. As LTAR site locations accumulate phenocam imagery, analyses will be expanded across the network to quantitatively evaluate the role of growing season dynamics and climate on primary productivity in agro-ecosystems.

}, author = {Dawn M. Browning and Ponce Campos, Guillermo and R.L. Scott and Debra C. Peters} } @article {JRN54899, title = {Playa-wetlands effects on dryland biogeochemistry: space and time interactions}, journal = {Journal of Geophysical Research - Biogeosciences}, year = {2018}, abstract = {

Playas are ephemerally flooded wetlands found in hydrologically closed dryland catchments. Recent research showed how upland-catchment biophysical characteristics control the amount of organic carbon and nutrients that accumulates in playas from upland grasslands and shrublands. Here we further explored the role of allochthonous and autochthonous processes in fixing carbon and accruing soil nutrients in playas across a desert basin. We assessed whether playas contribute soil nutrient, organic-carbon stocks, and primary productivity rates in amounts disproportionately higher or lower than upland grasslands and shrublands. We found that playas had higher soil carbon and nutrient storage but no difference in mean annual primary production. Playas, on average, had similar primary productivity than upland systems, because they exhibited lower productivity during extremely wet years that offset the larger productivity during average or below average precipitation years. These results suggest that playas contain higher carbon and soil nutrient stocks because of runoff-mediated allochthonous inputs, rather than autochthonous sources, since long-term average productivity was similar to upland ecosystems. We also used the precipitation-aboveground net primary production (ANPP) relationships to accurately measure run-on in playas using differences between playa and upland grassland ANPP. The dependence of playa ANPP on surface-water inputs from upland catchments makes them susceptible to future changes in extreme precipitation events.

}, keywords = {climate change, desert playas, groundwater recharge, Jornada LTER, organic carbon, precipitation variability, soil nutrients, watershed ecology}, doi = {10.1029/2017JG004176}, url = {files/bibliography/JRN54899.pdf}, author = {Owen P. McKenna and O. E. Sala} } @article {JRN54829, title = {Phenocams bridge the gap between field and satellite observations in an arid grassland ecosystem}, journal = {Remote Sensing of Environment}, volume = {9, 1071}, year = {2017}, month = {10/2017}, abstract = {

Near surface (i.e., camera) and satellite remote sensing metrics have become widely used indicators of plant growing seasons. While robust linkages have been established between field metrics and ecosystem exchange in many land cover types, assessment of how well remotely-derived season start and end dates depict field conditions in arid ecosystems remain unknown. We evaluated the correspondence between field measures of start (SOS; leaves unfolded and canopy greenness \> 0) and end of season (EOS) and canopy greenness for two widespread species in southwestern U.S. ecosystems with those metrics estimated from near-surface cameras and MODIS NDVI for five years (2012-2016). Using the Timesat software to estimate SOS and EOS from the phenocam green chromatic coordinate (GCC) greenness index resulted in good agreement with ground observations for honey mesquite but not black grama. Despite differences in the detectability of SOS and EOS for the two species, GCC was significantly correlated with field estimates of canopy greenness for both species throughout the growing season. MODIS NDVI for this arid grassland site was driven by the black grama signal although a mesquite signal is discernable in average rainfall years. Our findings suggest phenocams could help meet myriad needs in natural resource management.

}, doi = {doi:10.3390/rs9101071}, url = {files/bibliography/17-027.pdf}, author = {Dawn M. Browning and Jason W. Karl and Moran, David and Andrew D. Richardson and Craig Tweedie} } @article {JRN54668, title = {Pushing precipitation to the extremes in distributed experiments: recommendations for simulating wet and dry years}, journal = {Global Change Biology}, volume = {23}, year = {2017}, pages = {1774-1782}, abstract = {

Intensification of the global hydrological cycle, ranging from larger individual precipitation events to more extreme multiyear droughts, has the potential to cause widespread alterations in ecosystem structure and function. With evidence that the incidence of extreme precipitation years (defined statistically from historical precipitation records) is increasing, there is a clear need to identify ecosystems that are most vulnerable to these changes and understand why some ecosystems are more sensitive to extremes than others. To date, opportunistic studies of naturally occurring extreme precipitation years, combined with results from a relatively small number of experiments, have provided limited mechanistic understanding of differences in ecosystem sensitivity, suggesting that new approaches are needed. Coordinated distributed experiments (CDEs) arrayed across multiple ecosystem types and focused on water can enhance our understanding of differential ecosystem sensitivity to precipitation extremes, but there are many design challenges to overcome (e.g., cost, comparability, standardization). Here, we evaluate contemporary experimental approaches for manipulating precipitation under field conditions to inform the design of {\textquoteleft}Drought-Net{\textquoteright}, a relatively low-cost CDE that simulates extreme precipitation years. A common method for imposing both dry and wet years is to alter each ambient precipitation event. We endorse this approach for imposing extreme precipitation years because it simultaneously alters other precipitation characteristics (i.e., event size) consistent with natural precipitation patterns. However, we do not advocate applying identical treatment levels at all sites {\textendash} a common approach to standardization in CDEs. This is because precipitation variability varies \>fivefold globally resulting in a wide range of ecosystem-specific thresholds for defining extreme precipitation years. For CDEs focused on precipitation extremes, treatments should be based on each site{\textquoteright}s past climatic characteristics. This approach, though not often used by ecologists, allows ecological responses to be directly compared across disparate ecosystems and climates, facilitating process-level understanding of ecosystem sensitivity to precipitation extremes.

}, keywords = {climate extremes, drought, field experiments, precipitation regimes, wet years}, doi = {10.1111/gcb.13504}, url = {files/bibliography/JRN00660.pdf}, author = {A. K. Knapp and Avolio, Meghan L. and Claus Beier and Carroll, Charles J. W. and S.L. Collins and Dukes, Jeffrey S. and Fraser, Lauchlan H. and Griffin-Nolan, Robert J. and David L. Hoover and Jentsch, Anke and Loik, Michael E. and Richard P. Phillips and Post, Alison K. and O. E. Sala and Slette, Ingrid J. and Laura Yahdjian and M. D. Smith} } @article {JRN54785, title = {Predictor variable resolution governs modeled soil types}, volume = {62}, number = {17}, year = {2017}, month = {06/2017}, chapter = {6}, address = {CSA News}, abstract = {

Soil mapping identifies different soil types by compressing a unique suite of spatial patterns and processes across multiple spatial scales. It can be quite difficult to quantify spatial patterns of soil properties with remotely sensed predictor variables. More specifically, matching the right scale of a given predictor variable with a specific soil type remains a challenge in digital soil mapping. An example of how scaling predictor variables derived from remote sensing and topographic indices can affect classification accuracy of soil types in southeastern Arizona is presented in the March{\textendash}April 2017 issue of the Soil Science Society of America Journal. Support vector machine and random forest approaches produced the best results across a range of circular buffer windows for averaging predictors (0{\textendash}180 m) compared with other commonly used machine learning models. Classification accuracy increased with the size of averaging window up to 150 m; however, larger window resolution produced general soil maps that poorly identified soils with narrow, linear features. Incorporating multiscale predictors produced soil{\textendash}landscape features with a mix of general and detailed patterns.
These findings suggest that traditional soil survey concepts can inform new soil mapping efforts and optimize the extraction of landscape information to predict soil properties.

}, author = {Matthew Levi} } @proceedings {JRN54797, title = {Predicting Potential C Mineralization of Tundra Soils Using Spectroscopy Techniques}, volume = {April 25-26, 2017, Potomac, MD}, year = {2017}, month = {4/2017}, publisher = {DOE Environmental System Science (ESS)}, address = {Potomac, MD}, abstract = {

The large amounts of organic matter stored in permafrost-region soils are preserved in a relatively undecomposed state by the cold and wet environmental conditions limiting decomposer activity. With pending climate changes and the potential for warming of Arctic soils, there is a need to better understand the amount of the carbon stored in the soils of this region and its potential susceptibility to mineralization. Studies have suggested that soil C:N ratio or other indicators based on the molecular composition of soil organic matter could be good predictors of potential decomposability. In this study, we investigated the capability of diffuse reflectance Fourier-transform mid infrared (DRIFT) spectroscopy to predict the evolution of carbon dioxide (CO2) produced by Arctic tundra soils during a 60-day laboratory incubations. Soils collected from four tundra sites on the Arctic Coastal Plain and Foothills of the North Slope of Alaska were separated into active-layer organic, active-layer mineral, and upper permafrost and incubated at 1, 4, 8 and 16{\textdegree}C. Carbon dioxide production was measured throughout the incubations. Total soil organic carbon (SOC) and total nitrogen (TN) concentrations, and the DRIFT spectra of the soils were measured. Multivariate partial least squares (PLS) modeling was used to predict cumulative CO2 production, and the other measurements. DRIFT reliably estimated SOC, TN and the C:N of these soils. Predictive CO2 production models were good across the different temperatures (1{\textdegree}C, R2 =0.77; 4{\textdegree}C, R2=0.82; 8{\textdegree}C, R2=0.82; 16{\textdegree}C, R2=0.80), for soil horizons (Organic, R2=0.70; Mineral, R2=0.79; Permafrost, R2= 0.77), and for soils with low C and N concentrations (SOC\<10\%, R2=0.80; TN\<2\%, R2=0.76). The number of PLS factors involved varied across different CO2 production models from 7 to 19. Analysis of the standardized beta coefficients from the PLS models of CO2 production indicated a small number (8) of influential spectral bands. These bands were associated with clay mineral contents, silicates, and phenolic OH, aliphatic, carboxylic acid, and polysaccharide compounds. These bands were further explored to determine their relative importance in explaining CO2 production in soils and their indicator capabilities. Our results demonstrate that the DRIFT spectra contained information that can be used for predicting potential decomposability of tundra soils.

}, author = {Matamala, R. and Jastrow, J. and Zhoasheng Fan and Liang, C. and Calderon, Francisco and Michaelson, G. and Ping, C. and Mishra, U.} } @article {JRN54812, title = {Percolation observations in an arid piedmont watershed and linkages to historical conditions in the Chihuahuan Desert}, journal = {Ecosphere}, volume = {8}, year = {2017}, pages = {Article e02000}, abstract = {

A critical hydrologic process in arid and semiarid regions is the interaction between ephemeral channels and groundwater aquifers. Generally, it has been found that ephemeral channels contribute to groundwater recharge when streamflow infiltrates into the sandy bottoms of channels. This process has traditionally been studied in channels that drain large areas (tens to hundreds of square kilometers). Since the water table in arid and semiarid regions is typically far from the surface, measured streamflow losses or percolation into the deep vadose zone is equated to groundwater recharge. In this study, we use a water balance approach to estimate deep percolation in a first-order, instrumented watershed (4.7 ha) on a piedmont slope of the Jornada Experimental Range (JER) in the Chihuahuan Desert. Results indicate that runoff generated within the piedmont slope contributes significantly to deep percolation. During the short-term 6-yr study period, we estimated 385 mm of total percolation, 62 mm/yr, or a ratio of percolation to rainfall of 0.26. Based on the instrument network, we identified that percolation occurs inside channel areas when these receive overland sheetflow from hillslopes. We observed less streamflow leaving the watershed as compared to percolation during the study period, leading to an outlet streamflow to rainfall ratio of 0.02. Using long-term data sets available from the JER, we estimate that over the last 100 yr, 48 mm/yr of percolation occurs at the study site, a ratio of percolation to rainfall of 0.19. We then scale this up to determine the contribution of similarly sized watersheds on the piedmont slopes of the JER. These observations highlight the importance of arid piedmont slopes for generating groundwater recharge, in particular during above-average rainfall periods.

}, keywords = {Chihuahuan Desert, dryland ecohydrology, groundwater recharge, long term ecological research, Special Feature: Dynamic Deserts, watershed instrumentation}, doi = {10.1002/ecs2.2000 }, url = {files/bibliography/JRN00659.pdf}, author = {A. P. Schreiner-McGraw and Enrique Vivoni} } @article {JRN54597, title = {Point discharge current measurements beneath dust devils}, journal = {Journal of Atmospheric and Solar{\textendash}Terrestrial Physics}, volume = {150}, year = {2016}, pages = {55-60}, abstract = {

We document for the first time observations of point discharge currents under dust devils using a novel compact sensor deployed in summer 2016 at the USDA-ARS Jornada Experimental Range in New Mexico, USA. A consistent signature is noted in about a dozen events seen over 40 days, with a positive current ramping up towards closest approach, switching to a decaying negative current as the devil recedes. The currents, induced on a small wire about 10 cm above the ground, correlate with dust devil intensity (pressure drop) and dust loading, and reached several hundred picoAmps.

}, keywords = {atmospheric electricity, dust devils, meteorology}, doi = {http://dx.doi.org/10.1016/j.jastp.2016.10.017}, url = {/files/bibliography/16-023.pdf}, author = {Ralph D. Lorenz and Lynn D. Neakrase and John P. Anderson and Harrison, R. Giles and Nicoll, Keri A.} } @conference {JRN54449, title = {Protocols for vegetation and habitat monitoring with unmanned aerial vehicles: linking research to management on US public lands}, booktitle = {100th Annual Meeting of the Ecological Society of America}, year = {2015}, month = {08/2015}, publisher = {Ecological Society of America}, organization = {Ecological Society of America}, address = {Baltimore, MD}, abstract = {

Background/Question/Methods:\  Monitoring of the condition and trend of natural resources is critical for determining effectiveness of management actions and understanding ecosystem responses to broad-scale processes like climate change. While broad-scale remote sensing has generally improved the ability to monitoring ecosystems, many important fine-scale indicators must still be measured\ in situ\ through direct observation or via very-high-resolution (i.e., \< 10cm ground-sampling distance [GSD]) imaging. Recent research has shown that many field-derived indicators (e.g., cover, density, vegetation structure, canopy gaps) of ecosystems can be obtained via very-high-resolution (VHR) aerial photography or digital photogrammetric techniques. The relaxing of regulations on operating unmanned aerial systems (UAS) in national airspace in the United States has turned UAS into a viable platform for acquiring VHR imagery for natural resource monitoring programs. However, while much research has looked at using VHR imagery to estimate ecosystem indicators, the available technologies and techniques have not previously been synthesized into a protocol for integrating UAS-based image collection and analysis into a national monitoring program. Our objective was to create and test a multiple-indicator sampling protocol for UAS-based data collection that could be integrated into the Bureau of Land Management{\textquoteright}s Assessment, Inventory, and Monitoring program.Results/Conclusions: Our proposed protocol uses a double-sampling approach where statistical relationships between UAS-derived and field-measured indicators collected at the same locations are used to make indicator estimates to areas where only UAS images are collected. The protocol takes advantage of the UAS platform{\textquoteright}s ability to collect data quickly over field plot areas at GSD \< 1cm. Our protocol calls for use of a multi-rotor UAS (e.g., a {\textquotedblleft}quadcopter{\textquotedblright}) to collect downward-looking (i.e., nadir) images with 60\% forward overlap and 30\% sidelap augmented by oblique (i.e., 45{\textordmasculine} camera angle) images. The nadir images are used to assess, via image interpretation, vegetation cover by functional group, bare ground amount, and canopy gaps. The overlapping nadir and oblique images are used to create three-dimensional representations of the plot area to assess soil erosion, hydrologic connectivity, and vegetation height. We tested this protocol in Chihuahuan Desert shrubland sites and found a high degree of correspondence between field measurements and UAS-derived indicator estimates. The ability to realize the potential of UAS technologies for advancing monitoring of natural resources will depend not only on research verifying VHR imagery can be used to derive meaningful ecosystem indicators but also on being able to work these technologies into implementable protocols for monitoring programs.\  OOS-68-8.

}, author = {Jason W. Karl and Jeffrey K. Gillan} } @conference {JRN54409, title = {Preserving heterogeneity and consistency in hydrological model inversions by adjusting pedotransfer functions}, booktitle = {3rd Brazilian Soil Physics Meeting}, year = {2015}, month = {05/2015}, address = {Curitiban, Parana, Brazil}, abstract = {

Numerical modeling is the dominant method for quantifying water flow and the transport of dissolved constituents in surface soils as well as the deeper vadose zone.\  While the fundamental laws that govern the mechanics of the flow processes in terms of Richards{\textquoteright} and convection-dispersion equations are relatively simple in principle, the practical implementation and parametrization of realistic {\textquotedblleft}problems{\textquotedblright} remains difficult and fraught with many uncertainties.\  Besides defining appropriate boundary conditions (e.g., atmospheric forcing by rain and evapotranspiration as well as groundwater fluctuations), the practitioner must decide upon the dimensionality, space and time discretization and the internal structure of the problem (e.g., pedological structure and stratigraphy) and assign realistic hydraulic and chemical properties (water retention and unsaturated hydraulic conductivities and absorption coefficients) to all elements in the numerical grid.\ \  It is well-known that hydraulic properties are difficult to measure, making it virtually impossible to completely cover the variability within the simulated domain.\  Instead, inversion methods are often deployed which allows the determination of effective parameters by optimizing hydraulic parameters on observed time-series of moisture contents or matric potentials.\  Similar to laboratory measurements, field monitoring is expensive and problems with non-uniqueness of the inversion results often limits the level of detail that can be resolved in the subsurface.\  Without additional data or methods, lab measurements nor model inversions can completely characterize all the heterogeneity present at a site and the resulting model may therefore not be able to provide reliable flow estimates.

Pedotransfer functions are an alternative method for estimating hydraulic properties from {\textquotedblleft}cheap{\textquotedblright} and ubiquitous co-variates such as soil particle size and bulk density.\ \ \  The method is imperfect, however,\  because usually only approximate relations can be established that are database or site-specific and which do often not {\textquotedblleft}transfer{\textquotedblright} accurately to other locations.\ \  In this presentation we will discuss a method that will allow the preservation of heterogeneity by combining a 3D geostatistical model of texture and bulk density at a deep vadose zone site, with a pedotransfer function and model inversion.\  Instead of optimizing hydraulic parameters directly ({\textquoteright}direct optimization{\textquoteright}), the new method optimizes parameters in simple functions that scale pedotransfer estimates for the 3D geostatistical model.\  The new method has several advantages over typical inversion methods: 1) It does not require that the pedotransfer (PTF) model is perfect.\  Instead, the method allows the PTF to be adjusted to better represent the site. 2) It does not require that the site is sub-divided in homogeneous subdomains. as is typical for direct inversion methods.\  We will show that sub-division is still advisable, but that such sub-domains can retain their internal variability. 3) The new method leads to better results than direct optimization of hydraulic parameters and is amenable to cases where direct optimization is impossible (e.g. when data is sparse).\ \  The new method has a limited number of free parameters, ensuring a quick convergence upon a final solution.

Also presented some further refinements regarding a previously published PTF (Rosetta).\  Rosetta was previously optimized to predict van Genuchten-type\  (VG) hydraulic parameters without regarding the uncertainty of the VG parameters when they were optimized on measured data.\  We show that weighting by uncertainty improves the models performance (in terms of root mean square error) and virtually eliminates model bias.\  The new model also allows the computation of a full covariance matrix which is helpful for doing uncertainty analyses in numerical model simulations.

}, author = {Schaap, Marcel and Yongguang Zhang and Xu, Chi and Matthew Levi and Craig Rasmussen and Larsen, Josh} } @conference {JRN54427, title = {Projected future distribution of an invasive grass, Lehmann lovegrass, in the Chihuahuan Desert}, booktitle = {2015 LTER All Scientists Meeting}, year = {2015}, month = {08/2015}, address = {Estes Park, CO}, abstract = {

Lehmann lovegrass (Eragrostis lehmanniana), an invasive grass dominating many grassland sites in the Sonoran Desert, has had a limited distribution in the Chihuahuan Desert.\  Climate (precipitation and temperature) is suggested to be the main driver for the difference in the current spatial distributions of the species in the two deserts. Our goal was to predict the distribution of Lehmann lovegrass throughout the Chihuahuan Desert under current climate conditions and future climate scenarios. We used the SOILWAT model to simulate Lehman lovegrass seedling establishment at \> 60 locations in the US portion of the Chihuahuan Desert. We then extrapolated the results to the entire region by using the 1981-2010 mean precipitation and temperature data from PRISM and the soil data from the SSURGO database. Future climate conditions were adjusted as follows: daily temperature was increased by 2.5 oC, and daily precipitation was increased or decreased by 5 and 10\%. Our results showed that the simulated distribution of Lehmann lovegrass in the Chihuahuan Desert under current climatic conditions is mainly in the southern part of the region, similar to the observed distribution. The spatial distribution under future climate scenarios varies due to the combined effects of precipitation and temperature. The species distribution contracts when precipitation decreases 5 or 10\% or daily temperature increases 2.5 oC. The species distribution expands when temperature stays the same and precipitation increases 5 and 10\%. Our study shows that the distribution of Lehmann lovegrass in the Chihuahuan Desert will depend on the amount and direction of changes in future temperature and precipitation. This uncertainty in the projected distribution adds one more challenge to land management of this invasive grass under climate change. Paper No. 120.

}, author = {Jin Yao and Debra C. Peters} } @article {JRN53978, title = {The public water supply protection value of forests: A watershed-scale ecosystem services based upon total organic carbon}, journal = {Open Journal of Ecology}, volume = {4}, year = {2014}, month = {06/2014}, pages = {517-531}, chapter = {517}, abstract = {

We developed a cost-based methodology to assess the value of forested watersheds to improve water quality in public water supplies. The developed methodology is applicable to other source watersheds to determine ecosystem services for water quality. We assess the value of forest land for source water mitigation of total organic carbon (TOC) through the use of linked watershed and reservoir simulation models and cost-based valuation economics. Watershed modeling results indicated that expected urbanization will increase TOC loads to Converse Reservoir (Mobile, AL).\  Reservoir model results indicated that future median TOC concentrations increased by 1.1 mg\·L-1 between 1992 and 2020 at the source water intake. Depending upon dynamic reservoir TOC concentrations, additional drinking water treatment with powdered activated carbon (PAC) often is necessary between May and October to comply with Safe Drinking Water Act regulations. The cost for additional treatment was calculated using minimum and maximum volume treated with simulated TOC concentrations at the source water intake. Daily simulated TOC concentrations for the base scenario using 1992 land cover (3\% urban) were compared with simulated TOC concentrations following forest to urban land conversion predicted in the watershed by 2020 (22\% urban).\  The daily cost for additional drinking water treatment with PAC was calculated if simulated TOC concentrations exceeded 2.7 mg\·L-1. The mean increase in daily treatment costs between base and future scenarios ranged from $91 to $95 per km2 per day for forest land water purification ecosystem services.

}, keywords = {drinking water treatment, ecosystem services, land use change, urbanization, water quality}, doi = {10.4236/oje.2014.49042}, url = {/files/bibliography/14-021.pdf}, author = {Emile H. Elias and Leband, David and Dougherty, Mark and Lockaby, Graeme and Srivastava, Puneet} } @article {JRN54178, title = {Predicting risk of invasive species occurrence - remote-sensing strategies}, year = {2014}, pages = {59-77}, publisher = {US Department of Interior; US Geological Survey}, edition = {Scientific Investigations report 2012-5162}, chapter = {Chapter 6}, abstract = {

Remote sensing is a means to describe characteristics of an area without physically sampling the area. Remote sensors can be mounted on a satellite, plane, or other airborne structure. Remotely sensed data allow for landscape perspectives on management issues. Sensors measure the electromagnetic energy reflected from an object or area on the Earth{\textquoteright}s surface. These sensors measure energy at wavelengths that are beyond the range of human vision. The guiding principal is that different objects (for example, soils, plants, buildings, water) reflect and absorb light differently at varying wave{\textlnot}lengths. Graphically plotting the amount of radiation reflected at a given wavelength provides a unique signature for an object, especially if there is sufficient spectral resolution to distinguish its spectrum from those of other objects.\  Reflectance of clear water is typically low, with initial higher reflectance values in the blue end of the spectrum, which decreases as wavelength increases. Vegetation reflectance is typically low in both the blue and red regions of the spectrum due to absorption by chlorophyll. Because reflectance values peak at the green region, vegetation appears green. In the near infrared (NIR) region, reflectance is much higher than that in the visible bands due to leaf cellular structure. Therefore, vegetation can be identified by the high NIR but generally low visible reflectance. Spectral reflectance curves can be used to discriminate between vegetation types or plant species.

}, issn = {2012-5162}, doi = {10.3133/sir20125162}, url = {/files/bibliography/14-042.pdf}, author = {Kendal Young and Scott T. Schrader} } @article {49849, title = {Polyploidy enhances the occupation of heterogeneous environments through hydraulic related trade-offs in Atriplex canescens (Chenopodiaceae)}, journal = {New Phytologist}, volume = {197}, year = {2013}, month = {01/2013}, pages = {970-978}, chapter = {970}, abstract = {

Plant hydraulic characteristics were studied in diploid, tetraploid and hexaploid cytotypes of Atriplex canescens (Chenopodiaceae) to investigate the potential physiological mechanism underlying the intraspecific habitat differentiation among plants of different ploidy levels.\  Populations of A. canescens from different habitats of the Chihuahuan Desert (New Mexico, USA) were analyzed using flow cytometry to determine ploidy levels. Traits related to xylem water transport efficiency and safety against drought-induced hydraulic failure were measured in both stems and leaves.\  At the stem level, cytotypes of higher ploidy levels showed consistently lower leaf-specific hydraulic conductivity but greater resistance to drought-induced loss of hydraulic conductivity. At the leaf level, comparisons in hydraulics between cytotypes did not show a consistent pattern, but exhibited high plasticity to proximal environmental conditions related to soil water availability.\  The results suggest that there is a trade-off between stem hydraulic efficiency an safety across ploidy levels, which underlies the intraspecific niche differentiation among different cytotypes of A. canescens. Polyploidization is likely an important mechanism in adaptation to the environmental heterogeneity related to water availability, and variation in water-related physiology found in the present\  study suggests a fundamental basis for the coexistence of different cytotypes in desert environments.

}, keywords = {desert, drought tolerance, flow cytometry, niche differentiation, plant hydraulics, polyploidy, saltbush, water relations}, doi = {10.1111/nph.12051}, url = {/files/bibliography/13-007.pdf}, author = {Hao, Guang-You and M.E. Lucero and Stewat C. Sanderson and Zacharias, Elizabeth and Holbrook, N. Michele} } @conference {JRN53997, title = {Practical tools for monitoring and assessment of DLDD for economic assessments}, booktitle = {UNCCD 2nd Scientific Conference}, year = {2013}, month = {04/2013}, abstract = {

We will provide a series of brief introductions (4-8 minutes each) to a suite of practical tools that are being applied by land managers and policymakers throughout the world. The remainder of the side event will be devoted to hands-on demonstrations. The presentations will include both a description of the tools, and how they are being applied to guide land management at the local scale and (for some) to support national reporting to the UNCCD by the United States. The tools to be highlighted include (among others) (1) an entire dryland monitoring system that requires only a 1m stick, a single sheet of paper, and no ability to read or write (jornada.nmsu.edu + Riginos poster), (2) additional simple field tools including a 10 minute test for soil resistance to erosion (jornada.nmsu.edu + Herrick et al 2010 - Frontiers), (3) a user-friendly database for streamlining and standardizing data collection, and automatically generating land health indicators (jornada.nmsu.edu + Courtright Poster), (4) an assessment system for 3 key attributes of land health that has already been applied at over 30,000 locations (Herrick et al 2010 - Frontiers), (5) simple tools for analyzing aerial photography that do not require a background in GIS or remote sensing (landscapetoolbox.org), and (6) a tools for estimating how may measurements are needed at multiple spatial scales (landscapetoolbox.org). All of the tools and guides can be freely downloaded at jornada.nmsu.edu (click on \‘Monitoring\’) or landscapetoolbox.org, and some are available in several languages, including Chinese, Mongolian and Spanish.

}, author = {Jeffrey E. Herrick and Gordon R. Toevs} } @article {JRN52684, title = {Potential for using visual, auditory and olfactory cues to manage foraging behaviour and spatial distribution of rangeland livestock}, year = {2013}, abstract = {

This paper reviews the literature and reports on the current state of knowledge regarding the potential for managers to use visual (VC), auditory (AC) and olfactory (OC) cues to manage foraging behaviour and spatial distribution of rangeland livestock. We present evidence that free-ranging livestock use these sensory cues to make decisions about foraging, drinking, habitat selection and spatial distribution, and to detect and avoid predators. This knowledge provides managers with opportunities to favourably alter behavioural patterns of rangeland ungulates.\  Opportunities to use sensory cues to shape livestock spatial distribution patterns arise primarily from the abilities of animals to: (a) learn to respond to cue\–consequence associations that
enhance their ability to adapt to changing foraging environments on rangelands, (b) generalize learned cue\–consequence associations across spatial and temporal foraging scales and (c) influence one another\’s behaviour through social learning. Key literature on cue\–consequence principles is initially reviewed from fine-scale studies (e.g., controlled studies conducted in mazes, arenas).\  Applications of cue\–consequence principles are then highlighted from literature dealing with field-scale studies (e.g., controlled and observational studies conducted in large pastures or paddocks). We then discuss potential management implications derived from these studies.\  Finally, we summarize conclusions and recommendations for potential future research directions. The studies reviewed here suggest that VC, AC and OC associated with positive or negative reinforcers can be used to effectively direct livestock towards or away from selected areas.\  The feasibility of favourably altering grazing pressure on rangelands without having to build expensive, static fences has the potential to provide substantial economic and ecologic advantages.

}, keywords = {bonding, flerds, free-ranging livestock, grazing, rangeland management, Social models, Virtual fencing.}, doi = {10.1079/PAVSNNR20138049}, url = {/files/bibliography/13-030.pdf}, author = {Howery, Larry D. and Andr{\'e}s F. Cibils and D.M. Anderson} } @inbook {JRN52665, title = {Patterns of net primary production across sites}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {42-45}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {5}, address = {Springfield, Virginia}, abstract = {

Net primary production (NPP) is a fundamentally important and commonly measured ecosystem process that provides an integrative estimate of energy capture and flow into systems, and consequently the energy available for use by other trophic levels. A wide range of productivity levels occurs globally with high temporal dynamics among sites. This chapter discusses approaches to estimating NPP, highlights site-specific trends in productivity, and provides examples of past synthetic analyses across space and time. In terrestrial ecosystems, aboveground NPP are commonly measured or estimated. In many sites, spatial variation in NPP among locations within a site can overwhelm temporal variation.\  In terms temporal patterns, at some sites clear temporal trends exist: NPP either increases or decreases with time; at other sites, strong interannual variations exist.\  Past synthetic analyses have provided key insights into the relative roles of biotic versus abiotic drivers of dynamics as well as elucidating where and when biogeochemical versus climatic factors underlie patterns of NPP across biomes.\  The chapter proposes four questions that can be addressed as long-term data sets at more sites become available.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-5.pdf}, author = {A. K. Knapp and M. D. Smith and Debra C. Peters and S.L. Collins} } @article {49855, title = {Plant responses, climate pivot points, and trade-offs in water-limited ecosystems}, journal = {Ecosphere}, volume = {4}, year = {2013}, abstract = {

Plant species in dryland ecosystems are limited by water availability and may be vulnerable to increases in aridity. Methods are needed to monitor and assess the rate of change in plant abundance and composition in relation to climate, understand the potential for degradation in dryland ecosystems, and forecast future changes in plant species assemblages. I employ nearly a century of vegetation monitoring data from three North American deserts to demonstrate an approach to determine plant species responses to climate and critical points over a range of climatic conditions at which plant species shift from increases to decreases in abundance (climate pivot points). I assess these metrics from a site to regional scale and highlight how these indicators of plant performance can be modified by the physical and biotic environment. For example, shrubs were more responsive to drought and high temperatures on shallow soils with limited capacity to store water and fine-textured soils with slow percolation rates, whereas perennial grasses were more responsive to precipitation in sparse shrublands than in relatively dense grasslands and shrublands, where competition for water is likely more intense. The responses and associated climate pivot points of plant species aligned with their lifespan and structural characteristics, and the relationship between responses and climate pivot points provides evidence of the trade-off between the capacity of a plant species to increase in abundance when water is available and its drought resistance.

}, keywords = {arid, Chihuahuan Desert, climate change, Colorado Plateau, cross-site, desertification, early warning sign, long-term monitoring, plant canopy cover, Sonoran Desert}, doi = {10.1890/ES13-00132.1}, url = {files/bibliography/JRN00612.pdf}, author = {Seth M. Munson} } @article {49862, title = {Precipitation legacies in desert grassland primary production occur through previous-year tiller density}, journal = {Ecology}, volume = {94}, year = {2013}, month = {04/2013}, pages = {435-443}, chapter = {435}, abstract = {In arid ecosystems, current-year precipitation often explains only a small proportion of annual aboveground net primary production (ANPP). We hypothesized that lags in the response of ecosystems to changes in water availability explain this low explanatory power, and that lags result from legacies from transitions from dry to wet years or the reverse. We explored five hypotheses regarding the magnitude of legacies, two possible mechanisms, and the differential effect of previous dry or wet years on the legacy magnitude. We used a three-year manipulative experiment with five levels of rainfall in the first two years (-80\% and -50\% reduced annual precipitation (PPT), ambient, +50\% and +80\% increased PPT), and reversed treatments in year 3. Legacies of previous two years, which were dry or wet, accounted for a large fraction (20\%) of interannual variability in production on year 3. Legacies in ANPP were similar in absolute value for both types of precipitation transitions, and their magnitude was a function of the difference between previous and current-year precipitation. Tiller density accounted for 40\% of legacy variability, while nitrogen and carryover water availability showed no effect. Understanding responses to changes in interannual precipitation will assist in assessing ecosystem responses to climate change-induced increases in precipitation variability.}, keywords = {aboveground net primary production, ANPP, black grama, Bouteloua eriopoda, Chihuahuan Desert, desert grasslands, mesquite, precipitation legacies, prosopis glandulosa, rainfall manipulation, tiller dynamics}, doi = {10.1890/12-1237.1}, url = {/files/bibliography/13-017.pdf}, author = {Lara Reichmann and O. E. Sala and Debra C. Peters} } @proceedings {JRN54527, title = {Phenological patterns of Chihuahuan desert perennial grasses and shrubs in normal and below-average precipitation years}, volume = {Poster}, year = {2012}, month = {03/2012}, publisher = {Phenology Research and Observations of Southwest Ecosystems}, address = {Tucson, Arizona}, abstract = {Observations of plant phenology in Arid and semi-arid regions of the southwestern USA serve as salient indicators of plant responses to changing climate. Repeated consistent phenology observations in conjunction with local climatological (e.g., precipitation, temperature) and soil (e.g., moisture, temperature) measurements are key to elucidating the role of abiotic drivers in the timing of lifecycle events. We initiated weekly observations of plant phenology in March 2010 at a Soil Climate Analysis Network (SCAN) site on the Jornada Experimental Range in southern New Mexico. Weekly observations for 20 individuals across three functional groups - perennial grasses (Aristida purpurea, Sporobolus spp., and Pleuraphis mutica), the deciduous shrub honey mesquite (Prosopis glandulosa) and the evergreen shrub creosote (Larrea tridentata) {\textendash} were conducted using National Phenology Network (NPN) protocols. We compare and contrast phenology patterns by functional group in the context of precipitation for 2010 and 2011 rain years. Dates of first leaf (initial growth), open flowers and fruit production are noted; in addition, the time from initial growth to full canopy and from flower to fruit production were calculated for both growing seasons. Rainfall in the 2010 rain year (213.4-mm) was near the long-term average (245-mm). Aristida and Sporobolus grasses initiated growth prior to 17 Mar 2010. Mesquite initiated growth later (19 Apr 2010), but achieved full canopy within 4.5 weeks. In contrast, canopy development for grasses in 2010 occurred over 22 weeks. Time from first flower to fruit for grasses in 2010 ranged from 2 (for Sporobolus and Pleuraphis) to 2.7 weeks (for Aristida). Rainfall in the 2011 was far below average (89.4-mm) and encapsulated 242 consecutive dry days. Initial growth for all grasses was delayed until 11 Jul 2011, presumably due to deficit rainfall conditions. No grasses produced flowers or fruit in 2011. In contrast, mesquite and creosote shrubs initiated growth prior to the first rain event after 08 Oct 2010 (06 Jun 2011). We hypothesize that changes in soil temperature at depth trigger initial growth for deep-rooted shrubs. Next steps are to evaluate the soil temperature hypothesis with soil measurements and examine relationships between environmental variables and phenophase transitions using a proportional hazards model.}, author = {Dawn M. Browning and M. Mattocks} } @proceedings {JRN54534, title = {Patterns of soil community structure differ by scale and ecosystem type along a large-scale precipitation gradient}, volume = {COS 128-8}, year = {2012}, month = {08/2012}, publisher = {Ecological Society of America Abstracts}, address = {Portland, Oregon}, abstract = {Climate models predict increased variability in precipitation regimes, which will likely increase frequency/duration of drought. Reductions in soil moisture affect physical and chemical characteristics of the soil habitat and can influence soil organisms such as mites and nematodes. These organisms perform important roles in decomposition and nutrient cycling: changes to their community structuring have been shown to influence their contributions to these ecosystem processes. We investigated how soil moisture variation across regional scales might influence the community structure and population dynamics of mites and nematodes. Research consisted of three types of precipitation regimes: 1) a regional scale precipitation gradient of wet to dry: two grassland (wet{\textemdash}Konza Prairie, KS{\textemdash}KNZ; arid{\textemdash}Shortgrass Steppe, CO{\textemdash}SGS) and two desert (hot{\textemdash}Jornada Basin, NM{\textemdash}JRN; cold{\textemdash}McMurdo Dry Valleys, Antarctica{\textemdash}MCM) long-term ecological research (LTER) sites across the western US and Antarctica; 2) landscape-scale soil moisture gradients of three plots along a topographic transect at each site; and 3) existing experiments at each site manipulating natural variation in moisture availability. For 2 and 3, soil samples were collected once in fall of 2009 and three times each in 2010 and 2011, with nematodes and mites extracted, counted and sorted to trophic groups. Ordination analyses revealed that while nematode communities within two of the drier sites of the gradient (JRN and SGS) are similar, those of KNZ and MCM (the wettest and driest sites, respectively) are noticeably different. Regression analyses indicated patterns for nematode trophic groups across the entire gradient differ from those within individual sites; for example, across the entire gradient numbers of plant-feeding nematodes increase with available soil moisture, but within individual sites this pattern is only seen at JRN and decreases are observed at SGS and KNZ. In contrast, fungivorous nematodes increased with moisture across the entire gradient, while the only site displaying an increase was KNZ. Preliminary mite analyses suggest that mites also respond differently across different scales and sites. Soil moisture effects on soil invertebrate community structure appear to be dependent upon scale and ecosystem type. Notably, while populations of mites and nematodes tend to increase as sites increase in annual precipitation, in many cases populations decrease within sites as soil moisture increases. Future work will examine how modeling techniques may be employed to forecast changes to soil communities as moisture regimes are altered across regional and local scales.}, author = {Sylvain, Zachary A. and D.H. Wall and Karie Cherwin and Debra C. Peters and O. E. Sala and Lara Reichmann} } @conference {49937, title = {Patterns in reproductive phenology for dryland grasses and shrubs from 1993 to 2010 in the Chihuahuan Desert}, booktitle = {96th ESA Annual Meeting, Earth Stewardship: Preserving and enhancing earth{\textquoteright}s life-support systems}, year = {2011}, month = {08/2011}, publisher = {ESA}, organization = {ESA}, address = {Austin, TX}, abstract = {Arid and semi-arid regions of the southwestern USA are especially sensitive to changes in temperature as well as drought frequency and intensity. Timing of periodic life cycle events (i.e., phenology) is an integrated and salient indicator of plant responses to climate change. Spatially extensive phenology observations in these environments are uncommon and with few exceptions, there is a paucity of long-term records collected using standardized protocols. We examine an 18-year dataset of monthly observations of reproductive phenology for two species of perennial grasses and a deciduous shrub distributed across three upland grassland sites and three mesquite-dominated sites on the Jornada Basin LTER in southern New Mexico, USA. Our objective was to compare and contrast timing and duration of flower and fruit production for two perennial grass species (Bouteloua eriopoda [black grama], \ Sporobolus flexuosus [mesa dropseed]) with one co-existing shrub that has historically displaced grasses in this system (Prosopis glandulosa [honey mesquite]). Field observations are made monthly along two 75-m x 1-m belt transects at each site and constitute a count of individual plants in each of five phenophases: (1) dormant, (2) leaf-out with no reproductive structures, and producing (3) flowers, (4) seeds, or (5) fruits. The protocol simultaneously yields estimates of status and abundance. The appearance of first fruit for grasses (i.e., grains) occurred consistently in August or September, although the number of plants producing fruit was highly variable from year to year. Mesquite demonstrated remarkable synchrony in the production of first leaves (in April), flowers (in May), and fruit (in June) across four sites. The appearance of first fruit and peak fruit production was most often in the same month for mesquite and mesa dropseed. The time from first to peak fruit production in black grama was one month at two sites and in the same month at a third, suggesting local variability in rainfall or soil moisture dynamics may play a role in peak fruit production. Future analyses will examine relationships between the amount and seasonal distribution of rainfall with timing and abundance of fruit production. Understanding the role of abiotic factors in influencing the timing and success of reproductive events is especially relevant to the conservation and restoration of species of concern as well as in predicting plant responses to changes in climate.}, author = {Dawn M. Browning and John P. Anderson and Debra C. Peters} } @article {49934, title = {Protection from livestock fails to deter shrub proliferation in a desert landscape with a history of heavy grazing}, journal = {Ecological Applications}, volume = {21}, year = {2011}, month = {07/2011}, pages = {1629-1642}, chapter = {1629}, abstract = {Desertification is often characterized by the replacement of mesophytic grasses with xerophytic shrubs. Livestock grazing is considered a key driver of shrub encroachment, although most evidence is anecdotal or confounded by other factors. Mapping of velvet mesquite (Prosopis velutina) shrubs in and out of exclosures in 1932, 1948, and 2006 in semiarid grasslands of southeastern Arizona, USA, afforded the opportunity to quantify livestock grazing effects on mesquite proliferation over 74 years in the absence of fire to test the widespread assumption that livestock grazing promotes shrub proliferation. In 1932, shrub cover, density, and aboveground biomass were compared on grazed (12\%, 173 plants/ha, 4182 kg/ha) and newly protected areas (8\%, 203 plants/ha, 3119 kg/ha). By 1948, cover on both areas increased to 18\%; yet, density on the protected area increased 300\% (to 620 plants/ha), nearly twice that of the grazed area (325 plants/ha). From 1932 to 1948, differences in recruitment of new plants and growth of existing plants were reflected in biomass, which was higher on the protected area (415 plants/ha, 8788 kg/ha) relative to the grazed area (155 plants/ha, 7085 kg/ha), although mortality was equally low (0.06\%). In 2006, 42 years after an herbicide application reset mesquite cover to 10\% on both areas, aboveground mesquite mass was comparable on both areas (4700 kg/ha), but cover and density on the protected area (22\%, 960 plants/ha) exceeded that on the grazed area (15\%, 433 plants/ha). Mesquite mass in 2006 was substantially below 1948 levels, so continued accrual is likely. That shrub recovery from herbicides on a biomass basis was much less than recovery on a cover basis suggests that remotely sensed biomass estimates should integrate land management history. Contrary to widely held assumptions, protection from livestock since 1932 not only failed to deter woody-plant proliferation, but actually promoted it relative to grazed areas. Results suggest (1) that thresholds for grassland resistance to shrub encroachment had been crossed by the 1930s, and (2) fire management rather than grazing management may be key to maintaining grassland physiognomy in this bioclimatic region.}, keywords = {arid rangelands, land use legacy, landcover change, livestock grazing, mesquite, Prosopis velutina, shrub encroachment, shrub proliferation, Sonoran Desert, woody biomass}, doi = {10.1890/10-0542.1}, url = {/files/bibliography/11-014.pdf}, author = {Dawn M. Browning and Steven R. Archer} } @article {49953, title = {Patterns of net primary production across sites. Cross-site comparisons of state change dynamics}, year = {2011}, abstract = {

Net primary production (NPP) is a fundamentally important and commonly measured ecosystem process that provides an integrative estimate of energy capture and flow into systems and consequently of the energy available for use by other trophic levels. A wide range of productivity levels occurs globally (figure 5-1) with high temporal dynamics among sites (chapter 14). In this brief overview, we discuss approaches to estimating NPP, highlight site-specific trends in productivity, and provide examples of past synthetic analyses across space and time. We focus on aboveground components of NPP for reasons explained below.

}, keywords = {cross-site comparisons, global change, net primary production, NPP}, url = {files/bibliography/JRN00580.pdf}, author = {A. K. Knapp and M. D. Smith and Debra C. Peters and S.L. Collins} } @inbook {49978, title = {Perspectives on global change theory}, booktitle = {The Theory of Ecology}, year = {2011}, pages = {261-281}, publisher = {University of Chicago Press}, organization = {University of Chicago Press}, chapter = {12}, address = {Chicago}, abstract = {Human-caused global changes in ecological drivers, such as carbon dioxide concentrations, climate, and nitrogen deposition, as well as direct human impacts (land use change, species movements and extinctions, etc.) are increasingly recognized as key to understanding contemporary ecosystem dynamics, but a coherent theory of ecological responses to global change has not yet been developed. There are four attributes that characterize phenomena considered under global change (the direct and indirect effects of human actions) that collectively present unique challenges to existing theories. Two of these attributes occur under current conditions: (1) there is natural variation in environmental drivers and system responses within a hierarchy of interacting spatial and temporal scales, and (2) drivers and processes interact across scales such that spatial context and connectivity among spatial units are important to system dynamics; the other two attributes are unique to systems undergoing global change: (3) by definition, global change drivers have an anthropogenic origin that in many cases act outside the realm of natural selection, and (4) these drivers are changing in magnitude, frequency, and direction that result in trajectories of responses that differ from those studied in the past, and are often characterized by threshold behavior and regime shifts. We outline the characteristics of a theory of global change based on propositions derived from the four system attributes, and that draws upon existing theories from a range of sub-disciplines of ecology and other disciplines. This interacting scale theory has the potential to integrate much of our information about global change drivers and responses.}, keywords = {book, chapter, climate, ecological drivers, global change, human-caused, nitrogen}, url = {/files/bibliography/11-032.pdf}, author = {Debra C. Peters and Brandon T Bestelmeyer and A. K. Knapp} } @proceedings {49981, title = {Plant-soil feedbacks and the reversal of desertification with climate change}, year = {2011}, month = {04/2011}, pages = {292-296}, publisher = {International Rangeland Congress}, address = {Rosario, Argentina}, abstract = {Our objective was to provide a conceptual framework for perennial grass recovery in a series of wet years, which includes both plant-soil feedbacks that increase available water to grasses and effects of precipitation on a sequence of recovery-related processes. We tested hypotheses based on this framework for grasslands and shrublands in the Chihuahuan Desert, the largest desert in North America. Results show that a sequence of 5 wet years following 14 years of variable rainfall increased production in resource conserving ecosystem types greater than predicted based on rainfall alone. The increase in production was primarily by herbaceous plants, which captured water locally to increase plant available water to both existing plants and new recruits. The sequence of wet years allowed a series of linked plant processes to occur that resulted in the establishment and survival of perennial grasses and forbs. We predict that a continued series of wet years will maintain the herbaceous component of these systems, and may act to reverse desertification on degraded shrublands, and to maintain perennial grasslands without management inputs. Degraded shrublands located on slopes susceptible to runoff of water responded linearly to annual precipitation in multiple wet years, and are expected to be resistant to a shift back towards grasslands under a directional increase in precipitation.}, keywords = {Chihuahuan Desert, grasslands, precipitation, regime shift, shrublands}, url = {/files/bibliography/11-017.pdf}, author = {Debra C. Peters and Jin Yao and John P. Anderson and O. E. Sala} } @conference {49983, title = {Patchiness in wind erosion-deposition patterns in response to a recent state change reversal in the Chihuahuan Desert}, booktitle = {US-International Association for Landscape Ecology}, year = {2011}, month = {04/2011}, address = {Portland, OR}, abstract = {Shifts from shrub-dominated states to grasslands are believed to be irreversible as a result of positive feedbacks between woody plants and soil properties. In the Chihuahuan Desert, mesquite (Prosopis glandulosa) expansion into black grama (Bouteloua eriopoda) grasslands is maintained by wind redistribution of material from bare soil gaps to canopies beneath woody plants. However, a series of wet years starting in 2006 resulted in increased grass production, biomass, and lateral cover. We hypothesized that this increase in grasses modified the spatial distribution of gaps and therefore the patchiness of wind erosion-deposition dynamics. Further, we expected that positive feedbacks promoting grass recovery would act to interrupt long-term patterns of mesquite expansion. We tested this hypothesis by examining patterns of sand flux and changes in the spatial distribution of gaps through time in grasslands and shrublands at the Jornada Basin LTER from 1998 \– 2010. Wind-driven sediment deposition decreased markedly at mesquite-dominated sites beginning in 2007. The spatial variability of sediment deposition also decreased, indicating that an increase in the amount and homogeneity in herbaceous vegetation in previously unvegetated gaps reduced saltation by sand particles and stabilized the soil surface. These results indicate that a reduction in the spatial variability of bare gaps and changes in the structure of vegetated patches reduce the patchiness of wind erosion and deposition.\  Successful remediation of arid grasslands depends on our ability to exploit the altered spatial dynamics that have accompanied recent state change reversals.}, author = {Pillsbury, Finn C. and Debra C. Peters and Jin Yao and Gregory S. Okin} } @mastersthesis {49987, title = {Precipitation legacies on the functioning of arid ecosystems: biogeochemical and meristem density controls}, year = {2011}, month = {2011}, school = {Brown University}, type = {Ph.D Dissertation}, address = {Providence, RI}, abstract = {

In arid ecosystems, current-year precipitation often explains only a small proportion of annual aboveground net primary production (ANPP). We hypothesized that lags in the response of ecosystems to changes in water availability explain this low explanatory power, and that lags result from legacies from transitions from dry to wet years or the reverse. We explored five hypotheses regarding the magnitude of legacies, two possible mechanisms, and the differential effect of previous dry or wet years on the legacy magnitude. We used a three-year manipulative experiment with five levels of rainfall in the first two years (-80\% and -50\% reduced annual precipitation (PPT), ambient, +50\% and +80\% increased PPT), and reversed treatments in year 3. Legacies of previous two years, which were dry or wet, accounted for a large fraction (20\%) of interannual variability in production on year 3. Legacies in ANPP were similar in absolute value for both types of precipitation transitions, and their magnitude was a function of the difference between previous and current-year precipitation. Tiller density accounted for 40\% of legacy variability, while nitrogen and carry-over water availability showed no effect. Understanding responses to changes in interannual precipitation will assist in assessing ecosystem responses to climate change-induced increases in precipitation variability.

}, keywords = {arid ecosystems, biogeochemistry, black grama, Boutoloua eriopoda, carbon cycle, dissertation, grassland, meristem density controls, nitrogen cycle, precipitation, primary production, rainfall, rainout shelters, thesis}, url = {files/bibliography/JRN00581.pdf}, author = {Lara Reichmann} } @article {50013, title = {Practical guidance for developing state-and-transition models}, journal = {Rangelands}, volume = {32}, year = {2010}, month = {12/2010}, pages = {23-30}, chapter = {23}, abstract = {

State-and-transition models (STMs) are synthetic descriptions of the dynamics of vegetation and surface soils occurring within specific ecological sites. STMs consist of a diagram and narratives that describe the dynamics and its causes. STMs are developed using a broad array of evidence including historical information, local and professional knowledge, general ecological knowledge, and monitoring and experimental data from a specific ecological site or similar sites. We provide general guidance on the production of rangeland state-and-transition models with special attention to recent concepts. We describe preparation and a sequence of steps in the development of STMs that parallels the steps in ecological site development. STMs are usually developed alongside ecological site concepts because STMs help to define differences among sites. We follow the steps with a discussion of some common problems encountered by model developers and provide some advice for how to resolve them. We then conclude with some forward-looking ideas that bear upon the present-day development of STMs.

}, doi = {10.2111/RANGELANDS-D-10-00077.1}, url = {/files/bibliography/10-042.pdf}, author = {Brandon T Bestelmeyer and Moseley, Kendra and P. L. Shaver and H. Sanchez and D.D. Briske and Maria Fern{\'a}ndez-Gim{\'e}nez} } @proceedings {50020, title = {Precision of LVIS and MISR canopy height estimates for desert grassland shrub canopies assessed with field and UAV estimates in multiscale approach}, volume = {TUP2. PM.7}, year = {2010}, month = {07/25/2010}, address = {Honolulu, Hawaii}, abstract = {Many science questions in large-scale terrestrial ecology are concerned with changes in the Earth{\textquoteright}s carbon cycle and ecosystems and the consequences for the Earth{\textquoteright}s carbon budget, ecosystem sustainability, and biodiversity [1]. To address these questions, we must know the distribution of aboveground woody carbon stocks; how much, where, and why woody carbon stocks are changing; and what proportion of the annual net flux to/from land is the result of disturbance and recovery [2]. These questions can be addressed using measures of forest canopy physical structure (horizontal and vertical distributions) through the synergistic use of data from lidar and radar remote sensing instruments [3]. Although satellite systems with global observing capability are at least eight years away [4] many studies are being conducted to assess the capabilities and limitations of these technologies. It is known that full waveform lidar can provide good estimates of various canopy parameters, including height, in mediumdensity temperate forests, while performance in dense tropical and boreal forest and in shrub canopies is less well-defined. While savannas and grasslands with shrubs are low biomass environments, they are extensive, occupying around 40\% of the terrestrial land area. The goal of the research described here was thus to determine the performance of the NASA Laser Vegetation Imaging Sensor (LVIS) in estimating canopy height and aboveground standing live woody biomass in desert grasslands in southern New Mexico, USA, a region in which shrubs have mostly displaced native grasslands over the last 120 years.}, url = {/files/bibliography/10-025.pdf}, author = {M. Chopping and Aslan, Aslan and Hofton, Michelle and John M Blair and Andrea S. Laliberte and A. Rango} } @article {50031, title = {Prescribed burning to affect a state transition in a shrub-encroached desert grassland}, journal = {Journal of Arid Environments}, volume = {74}, year = {2010}, month = {2010}, pages = {1324-1328}, abstract = {

Prescribed burning is a commonly advocated and historical practice for control of woody species encroachment into grasslands on all continents. However, desert grasslands of the southwestern United States often lack needed herbaceous fuel loads for effective prescriptions, dominant perennial graminoids may have poor fire tolerance, and some systems contain fire-tolerant invasive species. We examined long term vegetation responses of black grama grassland that had been invaded by honey mesquite following a single prescribed burn. Vegetation responses to a 1995 prescribed burn were evaluated in a replicated randomized complete block design with a 2x2 factorial treatment structure. Treatments were prescribed burning and livestock exclusion for both a grassland-dominated and a shrub-encroached grassland state within a complex of sandy and shallow sandy ecological sites. Vegetation responses were measured in 2008, 13 years after the burn treatment application. Neither black grama basal cover not honey mesquite canopy cover were responsive (P\<0.05) to any treatment. A single prescribed burn would be ineffective as a shrub control practice in this environment. Repeated but infrequent prescribed burning within shrub encroached vegetative states, when used in combination with managed grazing, may be the management required for a transition to desert grassland states within these ecological sites.

}, keywords = {black grama, Bouteloua eriopoda, ecological sites, mesquite control, prosopis glandulosa, rangeland restoration, sandy ecological site}, doi = {10.1016/j.jaridenv.2010.05.035}, url = {/files/bibliography/10-017.pdf}, author = {Kris Havstad and D. K. James} } @article {50055, title = {Physiological and environmental regulation of interannual variability in CO2 exchange on rangelands in the western United States}, journal = {Global Change Biology}, volume = {16}, year = {2010}, note = {//USDA//LTER V/entered 02/03/2010, pdf available}, month = {2010}, pages = {990-1002}, abstract = {

For most ecosystems, net ecosystem exchange of CO2 (NEE) varies within and among years in response to environmental change. We analyzed measurements of CO2 exchange from eight native rangeland ecosystems in the western United States (58 site-years of data) in order to determine the contributions of photosynthetic and respiratory (physiological) components of CO2 exchange to environmentally caused variation in NEE. Rangelands included Great Plans grasslands, desert Shrubland, desert grasslands, and sagebrush steppe. We predicted that (1) week-to-week change in NEE and among-year-variation in the response of NEE to temperature, net radiation, and other environmental drivers would be better explained by change in maximum rates of ecosystem photorespiration at 10 {\textdegree}C (R10) and (2) among-year variation in the responses of NEE, Amax, and light-use efficiency to environmental drivers would be explained by changes in leaf area index (LAI). As predicted, NEE was better correlated with Amax than light-use efficiency or R10 for six of the eight rangelands. Week-to-week variation in NEE and physiological parameters correlated mainly with time-lagged indices of precipitation and water-related environmental variables, like potential evapotranspiration, for desert sites and with net radiation and temperature for Great Plains grasslands. For most rangelands, the response of NEE to a given change in temperature, net radiation, or evaporative demand differed among years because the response of photosynthetic parameters (Amax, light-use efficiency) to environmental drivers differed among years. Differences in photosynthetic responses were not explained by variation in LAI alone. A better understanding of controls on canopy photosynthesis will be required to predict variation in NEE of rangeland ecosystems.

}, keywords = {article, climatic variability, desert, grassland, journal, leaf area, light-use efficiency, method, Bowen ratio, NEE, net ecosystem exchange of CO2, precipitation, respiration, shrubland}, doi = {10.1111/j.1365-2486.2009.01966.x}, url = {files/bibliography/JRN50055.pdf}, author = {Polley, H. Wayne and Emmerich, William and James A. Bradford and P. L. Sims and Douglas A. Johnson and Nicanor Z. Saliendra and Svejcar, Tony and Angell, Raymond and Frank, Albert B. and Rebecca L. Phillips and K. A. Snyder and Jack A. Morgan} } @conference {JRN54481, title = {Performance of the snowmelt runoff model when remotely-sensed estimates of snow covered area are not available}, booktitle = {American Geophysical Union}, year = {2010}, month = {12/2010}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {The Snowmelt Runoff Model (SRM) is usually run with snow cover depletion data. These daily depletion data can be derived through interpolation of periodic, remotely sensed measurements of basin snow covered area (SCA). It is also possible to run SRM successfully without snow depletion data in {\textquotedblleft}no snow cover{\textquotedblright} mode. In this mode, accumulated winter precipitation is carried forward into the melt season. SRM will start to melt the accumulated winter precipitation incrementally when a degree-day threshold is passed. It is these data that are used in place of the daily snow cover depletion data.
We compared results from SRM run in three modes of operation: (i) {\textquotedblleft}no snow cover{\textquotedblright} mode, (ii) with depletion curves interpolated from SCA estimated using fine resolution satellite sensor data (30 m), and (iii) with depletion curves interpolated from SCA estimated using coarse resolution satellite sensor data (500 m). Comparisons were made for an average snow year (2001), a heavy snow year (2008) and a low snow year (2002) over 3 watersheds in the Upper Rio Grande basin. In this paper, we discuss the reasons why estimates of runoff differ between the three modes of operation. Factors that may contribute to the variation in the results include the quantity of precipitation preceding the melt season, basin size, basin elevation, proximity of climate stations and the quality of remotely sensed SCA data.
These results have relevance for water managers. If reasonable estimates of runoff from snowmelt can be obtained in {\textquotedblleft}no snow cover{\textquotedblright} mode, the usability of SRM is improved for the non-expert in remote sensing or when remotely-sensed SCA data are unreliable (e.g., in years of extreme cloudiness).}, author = {Caitriana Steele and A. Rango} } @article {50064, title = {Pack rats (Neotoma spp.): Keystone ecological engineers?}, journal = {Journal of Arid Environments}, volume = {74}, year = {2010}, note = {//NMSU,USDA//LTER V//entered 07/23/2010; pdf available}, month = {2010}, pages = {1450-1455}, chapter = {1450}, abstract = {

The potential role of two species of pack rats (Neotoma albigula) and Neotoma micropus) as keystone ecological engineers was examined by estimating the species diversity of invertebrates living in the nest middens, and nitrogen mineralization rates in soils associated with the middens. Although pack-rat middens in tarbush (Flourensia cernua) shrublands were smaller than those in creosotebush (Larrea tridentata) shrublands, they housed a higher abundance and diversity of arthropods. The Neotoma spp. middens were an important microhabitat for crickets (Gryllus sp.), wolf spiders (Lycosa spp.), and lycid beetle larvae (Lycidae) in all of the shrub habitats. There were five arthropod taxa that occupied all middens in the creosotebush shrubland, and 12 arthropod taxa that occupied all middens in the tarbush shrubland. Soils associated with pack-rat middens had significantly higher soil organic-matter content than reference soils. Nitrogen mineralization was significantly higher in soils associated with pack-rat middens than in reference soils. Neotoma spp. create habitats with moderate microclimates that are essential for several invertebrates, thus contributing to maintenance of biodiversity. The effects of middens on soil organic matter and nitrogen mineralization create nutrient-rich patches. Neotoma spp. affect biodiversity and critical ecosystem processes, thus supporting the designation of keystone ecological engineers. {\textcopyright} 2010 Published by Elsevier Ltd.

}, keywords = {habitat, mineralization, species diversity, stick nest, woodrat}, doi = {10.1016/j.jaridenv.2010.05.025}, url = {/files/bibliography/10-050.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @conference {50080, title = {Prospects of phenological monitoring in an arid southwestern U.S. rangeland using field observations with hyperspatial and moderate resolution imagery}, booktitle = {American Geophysical Union Fall Meeting}, year = {2009}, month = {12/2009}, address = {San Francisco, California}, abstract = {

Relating field observations of plant phenological events to remotely sensed depictions of land surface phenology remains a challenge to the vertical integration of data from disparate sources. This research conducted at the Jornada Basin Long-Term Ecological Research site in southern New Mexico capitalizes on legacy datasets pertaining to reproductive phenology and biomass and hyperspatial imagery. Large amounts of exposed bare soil and modest cover from shrubs and grasses in these arid and semi-arid ecosystems challenge the integration of field observations of phenology and remotely sensed data to monitor changes in land surface phenology. Drawing on established field protocols for reproductive phenology, hyperspatial imagery (4 cm), and object-based image analysis, we explore the utility of two approaches to scale detailed observations (i.e., field and 4 cm imagery) to the extent of long-term field plots (50 x 50m) and moderate resolution Landsat Thematic Mapper (TM) imagery (30 x 30m). Very high resolution color-infrared imagery was collected June 2007 across 15 LTER study sites that transect five distinct vegetation communities ranging from grass to shrub dominance. We examined two methods for scaling spectral vegetation indices (SVI) at 4 cm resolution: pixel averaging and object-based integration. Pixel averaging yields the mean SVI value for all pixels within the plot or TM pixel. Alternatively, the object-based method is based on a weighted average of SVI values that correspond to discrete image objects (e.g., individual shrubs or grass patches). Object-based image analysis of 4 cm imagery provides a detailed depiction of ground cover and allows us to extract species-specific contributions to upscaled SVI values. The ability to discern species- or functional-group contributions to remotely sensed signals of vegetation greenness can greatly enhance the design of field sampling protocols for phenological research. Furthermore, imagery from unmanned aerial vehicles (UAV) is a cost-effective and increasingly available resource and generation of UAV mosaics has been accomplished so that larger study areas can be addressed. This technology can provide a robust basis for scaling relationships for phenology-based research applications.

}, keywords = {computational methods, data processing, phenological, remote sensing}, author = {Dawn M. Browning and Andrea S. Laliberte and A. Rango and Jeffrey E. Herrick} } @article {50088, title = {Plant nitrogen and phosphorus limitation in 98 North American grassland soils}, journal = {Plant and Soil}, volume = {Online DOI 10.1007/s11104-009-0237-1}, year = {2009}, note = {//USDA//NONE//entered 12/09/2009. Published online. PDF available.}, month = {2009}, pages = {pp 1-12}, abstract = {The availability of nutrients is a critical determinant of ecological dynamics in grasslands, but the relationships between soil resource availability and nutrient limitation across ecosystems are not clear. To better understand how soil nutrient availability determines nutrient limitation in vegetation, we grew the same species of grass (Schizachyrium scoparium) in 98 North American grassland soils and fertilized them factorially with nitrogen (N) and phosphorus (P). On average adding N, P, and the two nutrients together increased biomass relative to unfertilized plants by 81\%, 22\%, and 131\%, respectively. Plants grown on low-P soils were not primarily limited by P. Instead, these plants were colimited by N and P, while plants grown on high-P soils were primarily limited by N and only secondarily limited by P. Limitation was not predicted by total soil N. The preponderance of colimitation between N and P on low-P soils suggests that low P availability alters the N cycle to constrain supplies to plants such that N and P are made available in proportion to their demand by plants.}, keywords = {article, biomass, grassland, colimitation, grass, Schizachyrium scoparium, grassland, journal, nitrogen, phosphorus, soil nitrogen, soil nutrients, nitrogen, soil nutrients, phosphorous, stoichiometry}, isbn = {0032-079X}, author = {Craine, Joseph Mitchell and Randall D. Jackson} } @conference {50106, title = {Patch-scale connectivity: Where and why does it matter?}, booktitle = {LTER All Scientists Meeting}, year = {2009}, month = {09/11/2009}, address = {Estes Park, Colorado}, abstract = {Patch-scale connectivity is frequently cited as a significant factor controlling redistribution of water, organic matter and nutrients in many arid and semi-arid ecosystems. The {\textquoteleft}leakiness{\textquoteright} of these systems has been cited as an indicator of degradation. Methods to limit or modify soil loss and redistribution are included in many restoration strategies. There are surprisingly few data, however, about the extent to which reducing connectivity at the patch to plot level results in increased resource retention or plant establishment, or how these effects might vary across the landscape. Our objectives were to (1) determine the extent to which reducing connectivity in plant interspaces can increase resource retention and plant establishment at plant and patch scales in three contrasting sites and (2) identify potential mechanisms and key landscape attributes that may explain among site differences. Two of the sites are on gravelly soils dominated by alluvial processes. One of these is on a geomorphically stable and the other on a geomorphically unstable surface. The third site is located on a sandy soil and is believed to be dominated by aeolian processes. Four paired treatment and control plots were established in late spring {\textendash} early summer 2008 and evaluated in fall 2008 with digital photographs. The results showed significant reductions in bare ground at all three sites that were associated with increases in litter cover. The reductions were much greater at the aeolian site (26\%) and the alluvial site on an geomorphically unstable surface (22\%) than on at the geomorphically stable, lower productivity site (3\%). Unique soil and geomorphic attributes at each of the sites are associated with mechanisms that may explain measured and observed differences. These preliminary results illustrate the importance of testing hypotheses about the importance of connectivity across a broad variety of plant communities and geomorphic surfaces.}, keywords = {connectivity, degradation, Patch-scale}, author = {Jeffrey E. Herrick and Debra C. Peters and Gregory S. Okin and John P. Anderson} } @conference {50105, title = {Prioritizing rangeland research and restoration based on societal outcomes}, booktitle = {62nd Society for Range Management Annual Meeting}, year = {2009}, month = {02/2009}, pages = {05-2}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Alb., NM}, abstract = {

Rangeland ecological research is generally driven by interest in a particular pattern, process or organism, by a desire to maximize a particular ecosystem service (such as livestock production) at a specific location, or by an interest in the effects of a particular management system on soils, vegetation or wildlife. Government managers and policymakers responsible for making the most effective use of funding to improve rangeland management are often required to base their decisions on science, but existing science is often inaccessible or irrelevant. It is also often presented in a form that makes it difficult to determine its relevance to management of a particular location. We propose a framework for increasing the relevance of science to policy and management, and the role of scientists in providing feedback to policymakers on how to increase the effectiveness of government programs that are designed to improve rangeland management. The framework consists of two components. The first is an ecological site-based system for prioritizing rangeland research, and for increasing the ability of managers to access and interpret relevant research results. This component includes a proposal for the adoption of a minimum set of required metadata for journal publications. The second component is designed to increase the quality and quantity of monitoring data collected in association with the implementation of conservation programs, and to increase the involvement of scientists in the interpretation of these data. We will conclude with a discussion of the benefits, costs and potential risks associated with adopting this framework.

}, keywords = {abstract, ecosystem, rangeland, SRM}, author = {Jeffrey E. Herrick and Thompson, D. and Brandon T Bestelmeyer and Joel R. Brown and Kris Havstad} } @conference {50122, title = {Preventing regime shifts on the Colorado Plateau: Application of ecological theshold concepts to land management decision making}, booktitle = {Ecological Society of America Abstracts}, year = {2009}, month = {August 2009}, pages = {PS 48-80}, abstract = {Investigating the mechanisms responsible for ecological thresholds is essential to understanding processes leading to ecosystem regime shifts. Dryland ecosystems are especially prone to threshold behavior wherein stressor-mediated alteration of patterns and processes can shift systems to alternative states resulting in compromised ecosystem services (e.g., maintenance of biological diversity and soil stability). Despite wide acceptance of the concept, few studies have used or quantified ecological thresholds for direct application to land management. By understanding and quantifying indicators of threshold behavior, land managers may be able to predict an ensuing threshold crossing and implement management actions to prevent a transition to persistent degraded conditions. We are using a combination of observational and experimental data, conceptual and simulation models, and meta-analyses to explore threshold dynamics across multiple ecological sites in dryland ecosystems of the Colorado Plateau region. A primary objective of this research is to determine indicators which (1) provide early warnings of ecosystem degradation in advance of a threshold crossing and (2) can be practically monitored by land management agencies of the Colorado Plateau region. Key degradational processes characteristic of dryland ecosystems include disturbance of biological soil crusts (BSCs), decreased soil stability and increased erosion, and invasion by nonnative plant species. Based on data from sites experiencing various disturbance intensities, we classified 10 biotic and abiotic degraded "syndromes" indicative of potential thresholds. Several syndromes were observed along axes using multivariate ordination. We detected nonlinear relationships between cover of BSCs and soil stability, with soil stability becoming unstable below thresholds in BSC cover. We used simulation models to understand the consequences of decreasing soil stability, and found wind erosion thresholds depend on interactions between soil stability, vegetation structure, and wind speed. Similarly, results suggest that invasions by nonnative plants and compositional shifts depend on interactions between soil properties, land use, proximity to invader propagules, and climate. These results illustrate that whereas general factors leading to degraded states or syndromes can be identified across regions, knowledge of specific mechanisms of threshold behavior for individual sites requires understanding interactions among multiple biotic and abiotic variables across spatial scales. We suggest that early warning indicators of regime shifts to degraded states must include a multivariate approach to quantifying threshold values for use by land management agencies.}, keywords = {ecosystem, regime shifts, stressor-mediated, threshold}, author = {M. Miller and S. L. Garman and Lauver,C.L. and Jayne Belnap and C.D. Allen and Brandon T Bestelmeyer and Jeffrey E. Herrick and D.A. Pyke and Gregory S. Okin and Seth M. Munson} } @conference {50131, title = {Production and biodiversity responses to extreme climatic events across a heterogeneous landscape}, booktitle = {US International Association for Landscape Ecology}, year = {2009}, abstract = {Rising concentrations of atmospheric gases are increasing temperatures globally, but the magnitude and trajectory of localized changes in precipitation are highly uncertain. This uncertainty in climate as a driver results in uncertainty in predictions of future ecosystem dynamics. To reduce this uncertainty, we used 18 years of ecosystem responses that included a series of both dry and wet years to predict future dynamics of a heterogeneous landscape consisting of grasslands and degraded shrublands. We show that long-term (150 year) historical trends in conversion between grasslands and shrublands can be either offset by multi-year increases in precipitation or reinforced by increases in drought. Production and biodiversity responses to extreme climatic events depend on the spatial context of the ecosystem, Although historical dynamics provide insights to the future, ecological response data collected under alternative climatic conditions are needed to account for uncertainty in the direction and magnitude of global change drivers in the future.}, keywords = {atmospheric, biodiversity, climatic, ecology, heterogeneous, temperatures}, author = {Debra C. Peters and Jin Yao and O. E. Sala} } @article {50160, title = { Patch structure dynamics and mechanisms of cyclical succession in a Patagonian steppe (Argentina).}, journal = {Journal of Arid Environments}, volume = {72}, year = {2008}, note = {//OTHER//LTER V//entered 06/02/2008 per DEP}, month = {2008}, pages = {1552-1561}, abstract = {The plant community in the Patagonian steppe is arranged in two structural patch types: scattered grasses and shrubs, which are often surrounded by a ring of grasses. Previous studies suggested that this pattern results from a cyclical succession driven by plant interactions. Although there is a good understanding of the factors affecting the formation of the grass rings encircling the shrubs, there is little evidence testing the causes of its fragmentation when the shrub dies, and the relation between the two structural patches. We evaluated the physiological status of two Stipa species in different degenerative stages of the ring surrounding Adesmia volckmanni shrubs, measuring microclimate and soil nutrients. Results support the cyclical succession model. As long as Adesmia shrubs are alive, both Stipa species coexist under its canopy, supported by facilitation via improved microclimate and nutrients under the shrub. After shrub death, degeneration of the ring of grasses is caused by competition. The species spatial distribution suggests that Stipa speciosa withstands poorer soil nitrogen levels than Stipa humilis. We suggest that when facilitation by the shrub ceases, S. speciosa may have a competitive advantage over S. humilis that may result in the dominance of S. speciosa in gaps between shrubs. {\textcopyright} 2008 Elsevier Ltd. All rights reserved.}, keywords = {article, journal, Patagonia, patch structure dynamics, succession}, author = {Armas, C. and Pugnaire, F. E. and O. E. Sala} } @book {50196, title = {Principles of Snow Hydrology}, series = {Principles of Snow Hydrology}, year = {2008}, month = {July 2008}, pages = {410}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, chapter = {410}, address = {Cambridge, NY}, abstract = {Snow hydrology is a specialized field of hydrology that is of particular importance for high latitudes and mountainous terrain. In many parts of the world, river and groundwater supplies for domestic, irrigation, industrial and ecosystem needs are generated from snowmelt, and an in-depth understanding of snow hydrology is of clear importance. Study of the impacts of global warming has also stimulated interest in snow hydrology because increased air temperatures are projected to have major impacts on the snow hydrology of cold regions. This book describes the factors that control the accumulation, melting, and runoff of water from seasonal snow packs over the surface of the earth. The book addresses not only the basic principles governing snow in the hydrologic cycle, but also the latest applications of remote sensing, and principles applicable to modeling Streamflow from snowmelt across large, mixed land use river basins. Individual chapters are devoted to climatology and distribution of snow, ground-based measurements and remote sensing of snowpack characteristics, snowpack energy exchange, snow chemistry, modeling snowmelt runoff (including the SRM model developed by Rango and others), and principles of snowpack management on urban, agricultural, forests, and range lands. This book is invaluable for al those needing an in-depth knowledge of snow hydrology. It is a reference book for practicing water resources managers and a textbook for advanced hydrology and water resources courses which span fields such as engineering, Earth sciences, meteorology, biogeochemistry, forestry and range management, and water resources planning.}, keywords = {book, chapter, hydrology, snow}, url = {http://www.cambridge.org/us/academic/subjects/earth-and-environmental-science/hydrology-hydrogeology-and-water-resources/principles-snow-hydrology}, author = {D. DeWalle and A. Rango} } @mastersthesis {50214, title = {Patterns of soil and vegetation change associated with grassland-shrubland transitions: a case study}, year = {2008}, note = {//USDA//LTER V//entered 7/23/2008; PDF availableProCite field[12]: In File, partial (7/23/2008)}, month = {2008}, pages = {152}, school = {New Mexico State University}, type = {pp}, address = {Las Cruces, New Mexico}, abstract = {The conversion of grasslands to shrublands has been a common feature of desertification in the northern Chihuahuan Desert and other arid and semi-arid regions of the world. This study examined the encroachment of mesquite (Prosopis glandulosa) onto grasslands dominated by tobosa (Pleuraphis mutica) and black grama (Bouteloua eriopoda) around Red Lake, a playa in the northwest corner of the USDA-ARS Jornada Experimental Range. To identify factors influencing mesquite encroachment, the influences of sand deposition onto the clay soils of the tobosa grasslands and soil properties (e.g., texture, gypsum content) were intensely studied. In addition, the influences of vegetation and erosion type (wind or water) on size and orientation of intercanopy gaps were assessed for all vegetation communities. Field vegetation assessments indicated that mesquite now dominates 55\% of the study area. GIS-based analyses of imagery from 1942 to 2003 found that mesquite dunelands replaced 37\% of the grasslands in the study area between 1942 and 1973, and dunelands subsequently increased only 3.7\% between 1973 and 2003. Mesquite encroachment was associated with increased size and decreased number of intercanopy gaps. Soil profile characterization revealed that mesquite encroachment may have been limited by high electrical conductivity and/or gypsum content of clay soils, but sand deposition on the surface did not appear to be a factor in the rate and extent of mesquite encroachment onto tobosa grasslands. In addition, cesium-137 analyses provided evidence for net erosion across the study area, with net deposition found only under grass canopies in the ecotones between the tobosa grasslands and the sand sheets dominated by mesquite dunelands. This research indicates that 1) sand deposition on fine-textured soils does not significantly facilitate mesquite encroachment; 2) the texture, electrical conductivity, and gypsum content of soils may affect the rate of mesquite encroachment but not the extent of colonization; 3) intercanopy gaps are influenced more by vegetation type (p < 0.05) than by wind or water vectors (p > 0.05); and 4) the formation of coppice dunes has led to the loss of landscape integrity.}, keywords = {dissertation, grassland-shrubland transition, soil change, soil function, soil characteristics, spatial variability, soil chemistry, soil erosion, soil patterns, soil properties, changes, soil, classification, soil, description, soil, drought, soil, methods, soil, vegetation changes, soil, vegetation on gypsum, soil,dune development, thesis, vegetation change, vegetation change, desertification, vegetation change, grass, vegetation change, wind erosion, vegetation change,mesquite influence, vegetation mapping, methods, vegetation mapping, photointerpretation, vegetation, history, vegetation, management, vegetation, patterns, vegetation, wind erosion, vegetation,gypsum soils, vegetation,shrub encroachment, vegetative succession, Prosopis dunes}, author = {N.K. Hansen} } @proceedings {50226, title = {Predicting soil erosion and deposition effects on plant establishment: A key to increasing restoration success}, volume = {1}, year = {2008}, month = {06/2007}, pages = {743}, abstract = {

Soil erosion and deposition can result in significant modification of the soil profile, including changes in soil surface texture and structure. A series of field studies and modeling exercises are currently being completed at the USDA-ARS Jornada Experimental Range, located in the northern Chihuahuan Desert in south-central New Mexico, USA to examine the effects of soil erosion and deposition on plant establishment. As predicted, model results showed that sand addition to the soil surface affected establishment differently depending on the amount of sand added and the initial soil texture. Field studies of areas where sand deposition has been occurring during past several decades indicate that plant community dynamics are controlled by a number of different factors in addition to sand deposition, and that feedbacks with the plant community itself are likely to be important. We conclude that careful characterization of site conditions and soil profile characteristics should be completed before restoration. At a minimum, changes in soil water characteristics should be predicted using texture relationships. In some cases, restoration treatments can be designed to improve water holding capacity by promoting soil deposition.

}, keywords = {land degradation, proceedings, restoration, seedling establishment, soil erosion}, url = {/files/bibliography/07-039.pdf}, author = {Jeffrey E. Herrick and Debra C. Peters and Brandon T Bestelmeyer and Gregory S. Okin and N.K. Hansen and Kris Havstad} } @proceedings {50233, title = {A procedure for orthorectification of sub-decimeter resolution imagery obtained with an unmanned aerial vehicle (UAV)}, year = {2008}, month = {April 28, 2009}, address = {Portland, OR}, abstract = {Digital aerial photography acquired with unmanned aerial vehicles (UAVs) has great value for resource management due to the flexibility and relatively low cost for image acquisition, and very high resolution imagery (5 cm) which allows for mapping bare soil and vegetation types, structure and patterns in great detail. While image acquisition is relatively straightforward, the creation of orthorectified, GIS-ready image mosaics presents multiple challenges. Those include relatively small image footprints, image distortion due to the use of low-cost digital cameras, difficulty in locating ground control points and in automatic generation of tie points, and relatively large errors in exterior orientation (camera position and attitude information from the UAV{\textquoteright}s GPS/IMU). We developed an automated procedure to improve the accuracy of the exterior orientation by matching the UAV images to an orthorectified reference image. Using the UAV reported exterior orientation and camera geometry, combined with the reference image and DEM, the algorithm simulates image acquisition and then computes the covariance between camera image and simulated image pixels. With this evaluation function, a heuristic search algorithm finds successive improvements to the external orientation, ultimately producing a corrected exterior orientation that allows orthorectification with minimal input of tie points and/or ground control points. The RMS error for a 5-cm resolution, 257-image mosaic was 48 cm. Cost and turnaround time for production of orthorectified mosaics from UAV imagery are considerable reduced due to less time and money spent on ground control point and manual tie point collection.}, keywords = {aerial photography, digital, high resolution, imagery, UAV}, url = {/files/bibliography/08-047.pdf}, author = {Andrea S. Laliberte and Craig Winters and A. Rango} } @article {50241, title = {Predicting and understanding ecosystem responses to climate change at continental scales}, journal = {Frontiers in Ecology and the Environment}, volume = {6}, number = {5}, year = {2008}, month = {June 2008}, pages = {273-280}, abstract = {

Climate is changing around the world across a range of scales from local to global, but ecological consequences remain difficult to understand and predict. Such predictions are complicated by changes in connectivity of resources, in particular water, nutrients, and propagules, that influence the way ecological responses scale from local to regional and from regional to continental. This paper describes ecological responses at regional to continental scales associated with four key meso-scale drivers that influence the ecosystems of the continental interior: drought, warming, snowpack disappearance, and altered fire regime. These drivers will affect, for example, atmospheric smoke, dust, and reactive nitrogen concentrations; stream discharge, nitrate concentrations, and sediment loads; and the vector-borne spread of invasive species and infectious diseases. A key component of the continental network should be simulation models that describe transport vectors, particularly atmospheric, hydrologic, and human transport processes, that connect different spatial scales.

}, keywords = {climate, continental scales, global ecosystem}, doi = {10.1890/070165}, url = {/files/bibliography/08-013.pdf}, author = {J. D. Marshall and John M Blair and Debra C. Peters and Gregory S. Okin and A. Rango and M. R. Williams} } @conference {50253, title = {Perspectives on global change theory}, booktitle = {Ecological Society of America Abstracts}, volume = {SYMP 2-7}, year = {2008}, month = {August 3, 2008}, abstract = {Global changes in ecological drivers, such as CO2 concentrations, climate, and nitrogen deposition, are increasingly recognized as key to understanding contemporary ecosystem dynamics, but a coherent theory of global change has not yet been developed. We outline the characteristics of a theory of global change that draws upon other theories from a range of sub-disciplines, including population biology, landscape ecology, and Earth system sciences. The theory is based on the following propositions: (1) global scale patterns can be understood via the hierarchy of interacting processes at finer scales, from plants to landscapes and regions, and fine-scale patterns often cannot be understood without knowledge of global processes; (2) dynamics at any location on the globe are affected to varying degrees by transfer processes that connect adjacent as well as distant locations, (3) transfer processes (wind, water, animals, humans) connect locations via the movement of organisms, materials, disturbance, and information, (4) spatial heterogeneity (i.e., pattern) determines how drivers and transfer processes interact across scales, and (5) the relative importance of fine- or broad-scale pattern-process relationships can vary through time, and alternate as the dominant factors controlling system dynamics. We develop the basis for this theory and provide supporting evidence for it. This multiple, interacting scale theory has the potential to integrate much of our information about global change drivers and responses.}, keywords = {abstract, abstracts, climate, ecological, global, nitrogen}, author = {Debra C. Peters and Brandon T Bestelmeyer and A. K. Knapp} } @proceedings {50263, title = {Predicitons for snow cover, glaciers and runoff in a changing climate}, year = {2008}, month = {09/2008}, pages = {277-280}, address = {Prague, Czech Republic}, abstract = {

The problem of evaluating the hydrological effects of climate change has opened a new field of applications for snowmelt runoff models. The Snowmelt Runoff Model (SRM) has been used to evaluate climate change effects on basins in North America, the Swiss Alps, and the Himalayas. Snow covered area depletes about one month earlier in response to warmer temperatures (+40C) with runoff peaks shifted accordingly. Runoff will be higher in winter at the expense of summer runoff. In glacerized basins, runoff is not only redistributed, but increased due to glacier melting. This improved knowledge facilitates long-term decisions concerning hydropower, flooding, water allocations, and water management in general.

}, keywords = {climate change, proceedings, runoff, snowmelt, SRM}, url = {/files/bibliography/08-038.pdf}, author = {A. Rango and J. Martinec} } @conference {50265, title = {Predictions for snow cover, glaciers and runoff in a changing climate}, booktitle = {Hydrology and Water Resrouces International Conference Proceedings}, year = {2008}, abstract = {The problem of evaluating the hydrological effects of climate change has opened a new field of applications for snowmelt runoff models. The Snowmelt Runoff Model (SRM) has been used to evaluate climate change effects on basins in North America, the Swiss Alps, and the Himalayas. Snow covered area depletes about one month earlier in response to warmer temperatures (+4oC) with runoff peaks shifted accordingly. Runoff will be higher in winter at the expense of summer runoff. In glacerized basins, runoff is not only redistributed, but increased due to glacier melting. This improved knowledge facilitates long-term decisions concerning hydropower, flooding, water allocations, and water management in general.}, keywords = {climate change, hydrology, runoff shifts, snowmelt runoff modelling, water management}, author = {A. Rango and J. Martinec} } @conference {50269, title = {Precipitation and nitrogen interactions in arid ecosystems}, booktitle = {Ecological Society of America Abstracts}, series = {93rd ESA Annual Meetings}, year = {2008}, month = {August 4-8, 2008}, pages = {COS 89-8}, address = {Milwaukee, WI}, abstract = {Arid and semi-arid ecosystems are among the most impoverished terrestrial systems in terms of water and nitrogen (N) availability. Productivity (NPP) is generally low, soil N pools are small and N loss through percolation is assumed to be negligible. Increased water availability can stimulate both N plant uptake (and hence NPP) and microbial N mineralization, but controls on N cycling are still poorly understood because of confounding temporal effects. We conducted an experiment with five levels of water input (-80\% reduced PPT, -50\% reduced, ambient PPT, +50\% increased, and 80\% increased PPT) and 2 levels of N fertilization in the Northern Chihuahuan desert (NM, USA) and estimated inorganic N pools, in situ net N mineralization and N leaching loss from the upper-root zone of N-NO-3 and N-NH-4.}, keywords = {abstract, nitrogen, terrestrail}, author = {Lara Reichmann and O. E. Sala and Debra C. Peters} } @article {50276, title = {Potential mechanisms to increase shrub intake and performance of small ruminants in Mediterranean shrubby ecosystems}, journal = {Small Ruminant Research}, volume = {74}, year = {2008}, month = {January 2008}, pages = {1-15}, abstract = {

Shrubby vegetation types called \“maquis\” and \“garrigue\” are widespread throughout the Mediterranean Basin, including the Adriatic littoral of Croatia. In Croatia and elsewhere, these shrublands represent traditional grazing areas and are a significant source of forage for small ruminants, particularly during the dry summer. Utilization of these Mediterranean shrublands is often limited by secondary compounds that adversely affect forage intake and animal health. Likewise, shrubs containing substantial quantities of secondary compounds dominate arid and semiarid rangelands globally. These secondary compounds reduce livestock productivity, cause significant toxicity and abortion problems, and reduce efficiency of use of rangeland shrubs worldwide. Feed additives (e.g., activated charcoal, polyethylene glycol, and calcium hydroxide) may be useful for enhancing shrub intake through decreased absorption and/or increased elimination of secondary compounds. The biological diversity of Mediterranean maquis vegetation may also positively influence shrub consumption by small ruminants. Consumption of combinations of shrubs containing varied classes of secondary compounds (e.g., tannins and saponins) may lead to complementary chemical interactions within the intestinal tract and/or post-absorption that reduces their toxic effects and/or increase efficiency of detoxification. Although goats consumed more total shrubs than sheep across experiments, both species responded similarly to supplemental charcoal, PEG, and calcium hydroxide.

}, keywords = {activated charcoal, calcium hydroxide, mediterranean shrub, polyethylene glycol, saponins, small ruminants, tannins, terpenes}, doi = {10.1016/j.smallrumres.2007.07.006}, url = {/files/bibliography/08-002.pdf}, author = {Rogosic, J. and Richard E. Estell and Ivankovic, S. and Kezic, J. and Razov, J.} } @article {50332, title = {Plant acclimation to elevated CO2--From simple regularities to biogeographic chaos}, journal = {Ecological Modelling}, volume = {200}, year = {2007}, note = {//USDA//LTER-V//entered 07-31-2007}, month = {2007}, pages = {433-451}, abstract = {Upon exposure to altered levels of CO2, plants express a variety of acclimations to CO2 directly, over and above acclimations to indirect changes in temperature and water regimes. These acclimations commonly include increased photosynthetic CO2 assimilation and increased water-use efficiency with reduced N content and reduced stomatal conductance. The robust generic acclimations are explicable by combining simple models of carboxylation, stomatal control, energy balance, and functional balance. Species- or genotype-specific acclimations are overlaid on these generic acclimations. Several such specific acclimations that are often seen are readily incorporated in an extended model. These specific acclimations generate a great spread of values in key performance measures of photosynthesis, water- and N-use efficiencies, and rates of water and N use, even among C3 species that are the focus of this work. These performance measures contribute strongly to relative fitness and thus to evolving biogeographic distributions. The spread in fitness values is so large as to impend {\textquotedblleft}chaotic{\textquotedblright} shifts in biogeography (and, ultimately, evolution) that are not understandable with models specific to species or functional groups; rather, a systematic study of key physiological and developmental parameters is merited. Also merited is a coherent extension of the model used here, or similar models, to include other phenomena, including mycorrhizal associations, transience in resource availability, etc. The composition of useful approximate fitness functions from physiological and allocational responses is a major challenge, with some leads originating from the model. In the search to extract patterns of responses, arguments based on the responses being close to optimal or adaptive will be misleading, in view of the absence of selection pressure to perform adaptively at high CO2 for over 20 million years. I offer suggestions for more useful research designs. {\textcopyright} 2006 Elsevier B.V. All rights reserved.}, keywords = {acclimation, article, biogeography, carbon dioxide, model, climate change, CO2, CO2, journal, model, CO2 exchange, model,carbon dioxide, models}, author = {V. P. Gutschick} } @conference {50349, title = {Prioritizing ecological research and restoration based on societal outcomes}, booktitle = {Ecological Society of America Abstracts}, year = {2007}, month = {August 5-10, 200}, pages = {SYMP 12-5}, abstract = {Ecological research is commonly driven by interest in a particular pattern, process or organism, or by a desire to maximize a particular ecosystem service at a specific location. Ecologists often use the latter to justify funding for the former. This approach often (though not always) leads to irrelevant responses to unimportant problems, and short-term, narrowly-focused local responses to long-term problems with regional to global causes and consequences. We present a strategy for prioritizing ecological restoration and related research. The strategy begins by comparing anticipated long-term societal requirements for ecosystem services with the ecological potential of the land, and with its current capacity to provide these services with and without restoration. Key processes involved in degradation and recovery are identified, together with the spatial and temporal scales at which these processes must be addressed. Research on key processes is used to develop general and site-specific principles that are then flexibly applied to develop and test management strategies. The process is flexible, iterative and at times chaotic as scientists{\textquoteright} understanding of ecosystem processes and the relative importance of different ecosystem services evolves, particularly where the relationships between ecosystem services and societal outcomes are unclear. We will conclude by describing how this strategy has been flexibly applied by the USDA-ARS Jornada Experimental Range and the Jornada LTER to organize research on fundamental ecosystem processes that supports the development of restoration and management tools. We also provide examples from Mexico and Honduras showing how elements of this process can be applied internationally. Throughout this presentation, we describe how government and university researchers can significantly increase their impact on societal outcomes through collaborations that build on the relative strengths of their respective infrastructures (e.g. long-term vs. short-term, and technician vs. graduate student-based research) and with non-profit organizations, private landowners and government agencies.}, keywords = {ecological, prioritizing, restoration, societal}, author = {Jeffrey E. Herrick and J.P. Dobrowolski and M. Ayarza and Brandon T Bestelmeyer and Joel R. Brown and E.L. Fredrickson and Kris Havstad and Debra C. Peters} } @article {50397, title = {Predicting leaf and canopy 15N compositions from reflectance spectra}, journal = {Geophysical Research Letters}, volume = {34}, year = {2007}, pages = {L02401}, abstract = {We explored whether 15N concentration could be predicted from reflectance spectra of fresh leaves, and, if so, whether the spectral features were related to the 15N concentration on a canopy scale. Leaf scale reflectance (R) measurements were conducted in Ghanzi, Botswana using a spectrophotometer in March 2005 and canopy scale leaf R was measured in a series of successional fields in Northern Virginia, USA using the same instrument in September 2005. Results showed that there was a strong correlation between foliar 15N concentration and spectral data in both visible and near-infrared wavelength regions. Stepwise regressions showed that the first-difference of the log1/R [(log 1/R)\&$\#$39;] could explain 76 to 92\% of the variation in foliar \ä15N, providing the most reliable correlations with foliar 15N at bands near 600 and 700 nm. The present study indicates the possibility of estimating fresh leaf 15N abundance from high-resolution reflectance at leaf and canopy levels.}, keywords = {15N, canopy nitrogen, leaf nitrogen, nitrogen, spectral reflectance}, doi = {10.1029/2006GL028506}, author = {L. Wang and Gregory S. Okin and Jin Wang and Howard Epstein and Stephen A. Macko} } @article {50404, title = {Patterns of speciation in the yucca moths: parallel species radiations within the Tegeticula yuccasella species complex}, journal = {Systematic Biology}, volume = {55}, number = {3}, year = {2006}, note = {//USDA//NONE//Entered 1/9/2006; updated 4/14/2008}, month = {2006}, pages = {398-410}, abstract = {The interaction between yuccas and yucca moths has been central to understanding the origin and loss of obligate mutualism and mutualism reversal. Previous systematic research using mtDNA sequence data and characters associated with genitalic morphology revealed that a widespread pollinator species in the genus Tegeticula was in fact a complex of pollinator species that differed in host use and the placement of eggs into yucca flowers. Within this mutualistic clade two nonpollinating {\textquotedblleft}cheater{\textquotedblright} species evolved. Cheaters feed on yucca seeds but lack the tentacular mouthparts necessary for yucca pollination. Previous work suggested that the species complex formed via a rapid radiation within the last several million years. In this study, we use an expanded mtDNA sequence data set and AFLP markers to examine the phylogenetic relationships among this rapidly diverging clade of moths and compare these relationships to patterns in genitalic morphology. Topologies obtained from analyses of the mtDNA and AFLP data differed significantly. Both data sets, however, corroborated the hypothesis of a rapid species radiation and suggested that there were likely two independent species radiations. Morphological analyses based on oviposition habit produced species groupings more similar to the AFLP topology than the mtDNA topology and suggested the two radiations coincided with differences in oviposition habit. The evolution of cheating was reaffirmed to have evolved twice and the closest pollinating relative for one cheater species was identified by bothmtDNAand AFLP markers. For the other cheater species, however, the closest pollinating relative remains ambiguous, and mtDNA, AFLP, and morphological data suggest this cheater species may be diverged based on host use. Much of the divergence in the species complex can be explained by geographic isolation associated with the evolution of two oviposition habits.}, keywords = {AFLP, article, coevolution, hose use, insect, Tegeticula, journal, mtDNA, parallel species radiation, speciation, yucca moth, yucca moth, speciation}, isbn = {ISSN: 1063-5157 print / 1076-836X online; DOI: 10.1080/10635150600697325}, author = {David M. Althoff and K. A. Segraves and J. Leebens-Mack and Pellmyr, O.} } @article {50431, title = {Productivity and species richness in an arid ecosystem: a long-term perspective}, journal = {Plant Ecology}, volume = {186}, year = {2006}, note = {//NMSU, USDA//LTER V//Entered 3/27/2007}, month = {2006}, pages = {1-12}, abstract = {

There is little consensus on the form of the relationship between biodiversity and productivity, and most of the research examining it has been done in temperate grasslands, with arid ecosystems receiving comparatively little attention. Using 9 years of data collected using standardized sampling methods from five different community types in the Chihuahuan Desert (Jornada Basin Long-Term Ecological Research site, New Mexico, USA), we evaluate the relationship between productivity and species richness at multiple spatial scales. The relationship was consistently unimodal at the largest scale considered; however, community types differed in both the form of the relationship and the degree to which patterns fluctuated over time. Although significant linear and unimodal patterns were evident, these models fit poorly, suggesting that annual primary productivity is a weak predictor of mean species richness in arid communities. We suggest that productivity {\textendash}diversity relationships are best described by a boundary that places an upper limit on species coexistence across the gradient of productivity for a site. This upper limit often appears to be maximized at intermediate levels of productivity, but it has relatively few points on the downward portion of the boundary. By focusing efforts on characterizing boundaries, approaches should be developed to determine the factors that are reducing species richness compared to what would be expected, given the level of productivity.

}, keywords = {arid ecosystem, article, journal, primary production, productivity, quantile regression, species richness, unimodal}, doi = {10.1007/s11258-006-9107-6}, url = {files/bibliography/JRN00456.pdf}, author = {S.H. Cox and Bloch, Christopher P. and Richard Stevens and L. Huenneke} } @article {50433, title = {Photoluminescent distinction among plant life forms using phosphate buffered saline extract solutions}, journal = {Applied Spectroscopy}, volume = {60}, number = {7}, year = {2006}, month = {2006}, pages = {800-807}, abstract = {Photoluminescence of plant extract solutions has been investigated for discrimination of plant life forms (grasses, forbs and shrubs) using principle componet analysis (PCA). Clippings from each of six plant species representing three different plant life forms potentially found in the diets of free-ranging herbivores in the Chihuahuan Desert of North America were investigated for possible discernment. These plants included Sporobolus flexuosus (mesa dropseed, a grass), Pleuraphis mutica (tobosa, a grass), Dimorphocarpa wislizenii (spectacle pod, a forb), Sphaeralcea incana (pale globemallow, a forb), Flourensia cernua leaves (tarbush, a shrub), and Atriplex canescens leaves and stems (fourwing saltbush, a shrub). Emission spectra (370-600 nm) from phosphate buffered saline (PBS) extract solutions (pH 2.2, 7.5 and 12.5) were recorded for each plant with excitation at 365 nm. Use of PBS minimized chlorophyll interference. Discernment among plant life forms within these plant species was achieved.}, keywords = {PCA, photoluminescence, plant extract, principel componet analysis}, url = {/files/bibliography/06-029.pdf}, author = {T.L. Danielson and S. Obeidat and G.D. Rayson and D.M. Anderson and E.L. Fredrickson and Richard E. Estell} } @article {50436, title = {Population and clonal level responses of a perennial grass following fire in the northern Chihuahuan Desert}, journal = {Oecologia}, volume = {150}, year = {2006}, month = {August 2006}, pages = {29-39}, abstract = {

Our objective was to evaluate effects of fire, grazing, and clone size on response of Bouteloua eriopoda (black grama) in southern New Mexico. Small, medium, and large clones were mapped in five 0.91-m2 quadrats prior and two years following fire and grazing treatments. Maximum fire temperature at ground level was measured as an estimate of fire intensity. Our results showed that almost all responses were independent of grazing. Basal and canopy cover, recruitment, and clone basal area decreased with increased fire temperatures. Fire did not kill clones regardless of size. Surviving clones resprouted rapidly following fire that was likely influenced by above-average precipitation, We conclude that additional studies are needed under different weather conditions.

}, keywords = {chronic fire regimes, clones, fire intensity, fire temperature, fuels, livestock grazing, perennial grass, precipitation, resprouting, southwestern United States}, doi = {10.1007/s00442-006-0502-4}, url = {/files/bibliography/06-037.pdf}, author = {Drewa, P.B. and Debra C. Peters and Kris Havstad} } @article {50440, title = {Plant-Animal Interactions}, volume = {10}, number = {1}, year = {2006}, month = {April 10, 2006}, pages = {3}, publisher = {Jornada Basin Long-Term Ecological Research Program}, address = {Las Cruces, NM}, abstract = {Shrub invasion into desert grasslands is an ongoing concern for ecologists and land managers. These shrubs typically contain chemicals that make them unpalatable for livestock and wildlife. Tarbush is a shrub that has invaded productive soils in the northern Chihuahuan Desert. For several years, we have been using tarbush as a model invasive shrub to explore the chemicals involved in plant-animal interactions. From a chemical standpoint, not all tarbush are alike. Sheep and goats select some tarbush plants and avoid others based on the concentration of volatile chemicals on the leaves. When we removed these chemicals using organic solvents, lambs ate more tarbush. Furthermore, when we removed these chemicals from tarbush and added them to a palatable food, animals ate less. We are now examining effects of individual compounds to determine if specific chemicals are critical drivers of diet selection. To date, we have tested effects of 23 volatile chemicals (primarily terpenoids) on intake by lambs, and two more compounds are currently being examined. Only four chemicals (camphor, alpha-pinene, camphene, and caryophyllene oxide) reduced the amount of food eaten. By learning which specific compounds drive diet selection, we hope to ultimately be able to manipulate browsing behavior of livestock and other herbivores.}, keywords = {jornada trails, plant-animal interactions}, url = {jornadalter/site/pubs/newsletr/jornv10i1.pdf}, author = {Richard E. Estell} } @inbook {50454, title = {Productivity and Desertification 2006}, booktitle = {Encyclopedia of Science}, year = {2006}, pages = {1375-1377}, author = {Kris Havstad} } @article {50463, title = {Partitioning resistance to overland flow on rough mobile beds}, journal = {Earth Surface Processes and Landforms}, volume = {31}, number = {10}, year = {2006}, note = {//NONE//LTER V//Entered 11/14/2006}, month = {2006}, pages = {1280-1291}, abstract = {

For overland flows transporting predominantly bed load over rough mobile beds without rainfall, resistance to flow f may be divided into four components: surface resistance fs, formresistance ff, wave resistance fw, and bed-mobility resistance fm. In this study it is assumed that f = fs + ff + fw + fm, and an equation is developed for each component. The equations forfs and ff are borrowed from the literature, while those for fw and fm are developed from two series of flume experiments in which the beds are covered with various concentrations oflarge-scale roughness elements. The first series consists of 65 experiments on fixed beds, while the second series contains 194 experiments on mobile beds. All experiments wereperformed on the same slope (S = 0{\textperiodcentered}114) and with the same size of sediment (D = 0{\textperiodcentered}00074 m). The equations for fw and fm are derived by a combination of dimensional analysis andregression analysis. The analyses reveal that the major controls of fw and fm are the Froude number F and the concentration of the roughness elements Cr. When the equations for fwand fm are summed, the Cr terms cancel out, leaving fw+m = 0{\textperiodcentered}63F-2. An equation is developed that predicts total f, and the contributions of fs, ff, fw and fm to f are computed from the series1 and 2 experiments. An analysis of the first series reveals that in clear-water flows over fixed beds, fw accounts for 52 per cent of f. A similar analysis of the second series indicates that insediment-laden flows over mobile beds fw comprises 37 per cent and fm 32 per cent of f, so that together fw and fm account for almost 70 per cent of f. Finally, regression analysesindicate that where F \>{\textperiodcentered}5, fw and fm each vary with F -2 and fw/fm = 1{\textperiodcentered}18. The equation developed here for predicting total f applies only to the range of hydraulic, sediment, andbed roughness conditions represented by the experimental data. With additional data from a broader range of conditions the same methodology as employed here could be used to developa more general equation. Copyright {\textcopyright} 2006 John Wiley \& Sons, Ltd.

}, keywords = {article, flow resistance, hillslope hydrology, journal, overland flow}, doi = {10.1002/esp.1333}, url = {files/bibliography/JRN00453.pdf}, author = {Hu, Shixiong and Athol D. Abrahams} } @inbook {50466, title = {Patterns of net primary production in Chihuahuan desert ecosystems}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem: The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {232-246}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {11}, address = {New York, NY}, abstract = {The Jornada Basin of southern New Mexico has long been an important location for the study of productivity in semidesert ecosystems. Researchers have studied the magnitude and sustainability of plant production since the founding of the USDA Jornada Experimental Range (JER) in 1912. The consistent administration and research focus of the Jornada Experimental Range and of the Chihuahuan Desert Rangeland Research Center (CDRRC) have facilitated a number of long-term studies of vegetation dynamics and productivity. These long-term datasets are especially critical for understanding semiarid ecosystems, where interannual and decadal scale variation in climate is so great and where plant performance is so strongly constrained by the physical environment. Long-term data, including the net primary productivity data that are the focus of this chapter, are also essential for understanding the progression or, rather, degradation of ecosystem structure that has been called desertification.}, keywords = {1912, magnitude, plant, production, productivity, sustainability}, url = {/files/bibliography/06-062.pdf}, author = {L. Huenneke and W. H. Schlesinger}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @article {50470, title = {Plant-fungal interactions in Arid and Semi-arid Ecosystems: Large-scale impacts from microscale processes}, journal = {Journal of Arid Environments}, volume = {65}, year = {2006}, month = {April 1, 2006}, pages = {276-284}, abstract = {

The roles microbes play in shaping plant communities have historically been underestimated. Recent improvements in our abilities to detect, identify, and monitor microbial inhabitants of plant tissues are driving appreciation of amazingly complex dynamics. Microbial endophytes can modify plants at genetic, physiologic, and ecologic levels, inducing profound changes in the way plants respond to their environment. Microscale examination of Bouteloua eriopoda (black grama) and Atriplex canescens (four-wing saltbush) has revealed diverse fungal communities associated with individual plants at the cellular and subcellular levels. To explore thresholds of plant fitness defined by microbial communities, we transferred fungi inhabiting two perennial grasses, B. eriopoda and Sporobolus cryptandrus (sand dropseed), and one shrub, A. canescens, to a variety of nonhost plant species. Dramatic, whole-plant differences in morphology and biomass between treated and untreated plants were observed. In most cases, endophyte transfer at the cellular level produced larger plants with greater reproductive potential than the untransformed counterparts. We hypothesize that these transformed plants will continue to grow, reproduce, and disperse more rapidly than their native counterparts, propagating changes from the plant-microbe interface to ecologically significant scales.

}, keywords = {large-scale impacts, microscale processes, plant-fungal interactions}, doi = {10.1016/j.jaridenv.2005.08.014}, url = {/files/bibliography/06-011.pdf}, author = {M.E. Lucero and J.R. Barrow and P. Osuna and Reyes, I.} } @inbook {50487, title = {Plant Communities in the Jornada Basin: The Dynamic Landscape}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem: The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {211-231}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {10}, address = {New York, NY}, abstract = {Plant communities of the Jornada Basin LTER are characteristic of the northern Chihuahuan Desert, both in structure and dynamics. Five major vegetation types are often distinguished that differ in plant species cover and composition, as well as other factors, such as animal populations, soil properties, and elevation. Similar to many other parts of the Chihuahuan Desert, these plant communities have experienced major shifts in vegetation over the past 50-150 years. The most dramatic changes in vegetation have occurred as a result of woody plant encroachment into perennial grasslands. In this chapter, we describe the characteristics of each vegetation type and the documented changes in each type at the Jornada. We also discuss the key drivers (small and larger animal activity, drought, fire, and directional changes in climate) influencing these vegetation dynamics.}, keywords = {Chihuahuan Desert, Jornada Basin, LTER, synthesis book}, url = {/files/bibliography/06-061.pdf}, author = {Debra C. Peters and Gibbens, Robert P.}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @conference {50496, title = {Photoluminescence spectroscopy for the discernment of plants within animal diets}, booktitle = {Proceedings of Pittcon Meeting}, year = {2006}, abstract = {Identification of different animal diets of free ranging herbivores is of much interest. Spectroscopic probes offer the potential for real-time analyses compared to microphitological procedures. The inherent multi-dimensionality of photoluminescence spectroscopy (i.e., fluorescence and phosphorescence) is a significant benefit for the analysis of chemically complex samples. Unfortunately, analysis of multi-dimensional data requires the use of algorithms other than simple linear regression at a single wavelength. To evaluate the utility of multi-dimensional luminescence spectroscopy for animal diet determinations, the excitatin-emission spectral signatures of each of seven diet components (i.e., diet supplement concentrate, Pistacia lentiscus, Phylirea Latifolia media, Pinus Brutia, alfalfa hay and clover hay) were acquired. Post-digested diet samples (i.e., feces) resulting from each hay component were also included.}, keywords = {animal, diet, photoluminescence, spectroscopic}, author = {G.D. Rayson and S. Obeidat and D.M. Anderson and Landau, S.Y. and Glasser, T.} } @conference {50497, title = {Plant inoculation with obligate endophytes from arid rangelands grasses: Implications for water usage}, booktitle = {Symposium on Efficient Water Use in the Urban Landscape}, year = {2006}, month = {February 23-24, }, address = {Las Cruces, NM}, abstract = { Endophytic inoculation of grasses can result in significant agronomic advantages including increased drought tolerance and disease resistance as well as enhanced water and nutrient uptake. While some endophytes can increase plant toxicity, others are thought to be strictly beneficial. New attempts to induce novel grass-endophyte associations with harmless endophytes are needed. By means of a novel biotechnology technique, we have transferred obligate biotrophic fungal endophytes from local rangeland grass species to novel host grasses. Important differences in root growth habbit and shoot/root ratio were apparent. Implications for plant water and nutrient uptake are discussed.}, keywords = {disease resistance, drought tolerance, endophytic, inoculation}, author = {I. Reyes-Vera and M.E. Lucero and J.R. Barrow} } @inbook {50507, title = {Patterns and Controls of Soil Water in 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 = {107-132}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {5}, address = {New York, NY}, abstract = {This chapter focuses on the controls and patterns of soil moisture in the Jornada Basin. First, we describe general properties that commonly contribute to soil water heterogeneity; secondly, we offer a brief overview of soil water research in the Jornada Basin; and lastly, we describe specific patterns of soil water content and availability observed in the Jornada Basin. Our goal is to describe general patterns of soil water that are likely to occur across the Chihuahuan Desert region.}, keywords = {Chihuahuan Desert, Jornada Basin, LTER, synthesis book}, url = {/files/bibliography/06-056.pdf}, author = {K. A. Snyder and K. A. Mitchell and Jeffrey E. Herrick}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @article {50588, title = {Phylogeny and life history evolution of Prodoxus yucca moths (Lepidoptera: Prodoxidae)}, journal = {Systematic Entomology}, volume = {DOI: 10.1111/j.1365-3113.2005.00301.x}, year = {2005}, note = {//USDA//LTER IV//Entered 1/9/06}, month = {2005}, abstract = {Yucca moths (Lep., Prodoxidae) are well-known for their obligate pollination mutualism with yuccas. In addition to the pollinators, yuccas also host many non-pollinating yucca moths. Here the genus Prodoxus, the nonpollinating sister group of the pollinators, is revised using morphological and molecular data, their phylogenetic relationships are analysed, and the evolution of host tissue specialization explored. Twenty-two species are recognized, including nine new species: Prodoxus gypsicolor sp.n., P. sonorensis sp.n., P. carnerosanellus sp.n., P. tamaulipellus sp.n., P. weethumpi sp.n., P. tehuacanensis sp.n., P. californicus sp.n., P. mapimiensis sp.n. and P. atascosanellus sp.n. Prodoxus y-inversus Riley, P. coloradensis Riley and P. sordidus Riley are redescribed. The genus Agavenema is synonymized with Prodoxus. Phylogenetic analyses indicated that stalk-feeding is basal within the group, that there are three separate origins of fruit-feeding, and one origin of leaf-mining from a stalk-feeding ancestor. Although species with different feeding habits often coexist within hosts, the analyses suggest that ecological specialization and diversification within a host only may have occurred within one or possibly two hosts.}, keywords = {article, insect, Prodoxus, insect, yucca moth, insect,population ecology, journal, phylogeny, Lepidoptera, phylogeny, Prodoxidae, phylogeny, Prodoxus, phylogeny, yucca moth, pollination mutualism, yucca moth, pollination, yucca moth, yucca moth, Prodoxus, Yucca, pollination, Yucca, Prodoxus, Yucca, reproduction, Yucca, yucca moth}, author = {Pellmyr, Olle and Balc{\'a}zar-Lara, Manuel and David M. Althoff and K. A. Segraves and J. Leebens-Mack} } @article {50720, title = {Plant water relations and photosynthesis during and after drought in a Chihuahuan Desert arroyo}, journal = {Journal of Arid Environments}, volume = {59}, number = {1}, year = {2004}, month = {October 1, 2004}, pages = {27-39}, abstract = {

In order to understand the physiology and ecology of perennial shrub species occupying the banks of ephemeral streams we studied the plant water relations and gas-exchange characteristics of six perennial shrub species growing along an ephemeral stream (arroyo) in the northern Chihuahuan Desert. Two of the species are restricted to riparian habitats (Brickellia laciniata and Chilopsis linearis), three are classified as semi-riparian (Fallugia paradoxa, Prosopis glandulosa, and Rhus microphylla) and one is considered to be non-riparian (Flourensia cernua). Differences in gas-exchange patterns and water relations emerged among these six species, yet differences among obligate, semi-riparian, and non-riparian classes of species were evident, but not universal. Chilopsis and Brickellia did not develop the low plant water potentials that characterized some semi-riparian (Rhus) and non-riparian species (Flourensia) during periods of drought. Rates of photosynthesis and transpiration were highest in Prosopis throughout the study, and were relatively constant in Chilopsis during and after drought. Whether water became available as channel flow or direct rainfall appeared to play a role in the physiology of these arroyo shrubs.

}, keywords = {channel flow, gas exchange, phreatophytic, plant water potential, rainfall, riparian}, doi = {10.1016/j.jaridenv.2004.01.011}, url = {files/bibliography/JRN00415.pdf}, author = {A.G. de Soyza and K.T. Killingbeck and Walter G. Whitford} } @article {50673, title = {Precipitation pulses and carbon fluxes in semiarid and arid ecosystems}, journal = {Oecologia}, volume = {141}, number = {2}, year = {2004}, month = {October 1, 2004}, pages = {254-268}, abstract = {In the arid and semiarid regions of North America, discrete precipitation pulses are important triggers for biological activity. The timing and magnitude of these pulses may differentially affect the activity of plants and microbes, combining to influence the C balance of desert ecosystems. Here, we evaluate how a {\textquoteright}pulse{\textquoteright} of water influences physiological activity in plants, soils, and ecosystems and how characteristics, such as precipitation pulse size and frequency are important controllers of biological and physical processes in arid land ecosystems. We show that pulse size regulates C balance by determining the temporal duration of activity for different components of the biota. Microbial respiration responds to very small events, but the relationship between pulse size and duration of activity likely saturates at moderate event sizes. Photosynthetic activity of vascular plants generally increases following relatively larger pulses or a series of small pulses. In this case, the duration of physiological activity is an increasing function of pulse size up to events that are infrequent in these hydroclimatological regions. This differential responsiveness of photosynthesis and respiration results in arid ecosystems acting as immediate C sources to the atmosphere following rainfall, with subsequent periods of C accumulation should pulse size be sufficient to initiate vascular plant activity. Using the average pulse size distributions in the North American deserts, a simple modeling exercise shows that net ecosystem exchange of CO2 is sensitive to changes in the event size distribution representative of wet and dry years. An important regulator of the pulse response is initial soil and canopy conditions and the physical structuring of bare soil and beneath canopy patches on the landscape. Initial condition influences responses to pulses of varying magnitude, while bare- soil/beneath-canopy patches interact to introduce nonlinearity in the relationship between pulse size and soil water response. Building on this conceptual framework and developing a greater understanding of the complexities of these ecohydrologic systems may enhance our ability to describe the ecology of desert ecosystems and their sensitivity to global change.}, keywords = {arid, biological activity, carbon fluxes, ecosystems, precipitation, pulses, semiarid}, url = {http://www.springerlink.com/media/99a0unmhlkdv8ypgdmwk/contributions/j/c/f/4/jcf4lnwltcxt7wga.pdf}, author = {T. Huxman and K. A. Snyder and Tissue, D. and Leffler, J. and Pockman, W.T. and Sandquist, D.R. and Potts, D.L. and Schwinning, S.} } @article {50714, title = {Patterns of tree dieback in Queensland, Australia: the importance of drought stress and the role of resistance to cavitation}, journal = {Oecologia}, volume = {139}, number = {2}, year = {2004}, month = {April 1, 2004}, pages = {190-198}, abstract = {During the extreme 1992{\textendash}1997 El Ni{\~n}o drought event, widespread stem mortality, or tree dieback, of both mature and juvenile eucalypts occurred within the tropical savannas of northeast Australia. Most of the dieback occurred in individuals of the ironbark species complex (Eucalyptus crebra {\textendash} E. xanthoclada) while individuals of the bloodwood species Corymbia erythrophloia, exhibited significantly less stem mortality. Indicative of greater water stress, predawn and midday xylem water potentials of ironbark adults and saplings were significantly more negative than predawn values of bloodwoods. The very negative xylem water potentials in ironbarks suggest that stem mortality in both adult and juvenile ironbarks results from drought-induced embolism and that ironbarks perhaps have a shallower and less extensive root system than bloodwoods. Although predawn and midday water potentials for ironbark adults and saplings were similar, a census of mature and juvenile ironbark trees indicated that mortality was higher in adult trees. Cavitation vulnerability curves indicated that ironbark saplings may be better buffered against cavitation than adult trees. If they possess smaller root systems, saplings are more likely than adults to experience low xylem water potentials, even in nondrought years. Xylem conduits produced in adult trees during periods of normal rainfall, although perhaps more efficient in water conduction, may be more vulnerable to cavitation during infrequent severe droughts.}, keywords = {drought stress, Eucalyptus, hydraulic conductance, water relations, xylem cavitation}, url = {http://springerlink.metapress.com/media/aflnygwtwrn8502g9m7j/contributions/3/x/g/9/3xg9c2kfhveb253a.pdf}, author = {Rice, K.J. and Matzner, S.L. and Byer, W. and Joel R. Brown} } @article {50730, title = {Pairwise species associations in the perennial vegetation of the northern Chihuahuan Desert}, journal = {The Southwestern Naturalist}, volume = {49}, number = {1}, year = {2004}, month = {March 1, 2004}, pages = {1-10}, abstract = {We analyzed pairwise species associations based on presence/absence data from transects of perennial vegetation at 129 sites located in the northern Chihuahuan Desert. The sites were chosen to represent the range of commonly encountered desert vegetation types from grassland to shrubland. Twenty-four significant associations were found, all of which were positive (i.e., the species pairs co-occurred more frequently than would be expected by chance). Some of the species associations identified by our analysis have been noted in the literature previously but others have not and warrant further investigation. Given the nature and scale of the data used in our analysis, the associations we uncovered most likely represent species with similarities in ecological requirements or tolerances but might or might not indicate strong interaction at the scale of individual plants.}, keywords = {Chihuahuan Desert, pairwise species, perennial vegetation}, url = {/files/bibliography/04-077.pdf}, author = {S.J. Turner and A. R. Johnson and Walter G. Whitford} } @conference {50742, title = {A perceived role of carbon and water management by systemic dark septate fungi in Bouteloua eriopida (Torr.) Torr. in an arid ecosystem}, booktitle = {Fourth International Conference on Mycorrhizae}, year = {2003}, month = {August 10-15, 20}, address = {Montreal, Canada}, abstract = {Dark septate endophytic (DSE) fungi are the prevalent symbionts of native grasses and shrubs in arid southwestern USA rangelands. The nature and extent of colonization of Bouteloua eriopida (Torr.) Torr., an important native range grass of the northern Chihuahuan Desert, was evaluated using dual staining, light and electron microscopy. Several unique and ecologically important features of DSE fungi were revealed. Fungi preferentially reside in the apoplastic environment and function as protoplasts identified by associated lipid bodies. They form systemic intercellular networks in plants and intracellular structures within sieve elements, parenchyma and cortical cells. Endophyte-free plants have not been developed but some fungi were cultured independently. The composite association results in a hybrid organism better equipped to survive in severe nutrient and water stressed ecosystems. Fungi formed stained and pigmented hyphae and microsclerotia, characteristic of DSE in less active tissues. Loosely organized hyphae, embedded within a mucilaginous matrix on the root surface, suggested a protective barrier from dry soil. A precisely organized hyphal network on the leaf surface suggested a protective barrier from atmospheric stress. Colonization of guard and subsidiary cells of the stomatal complex suggested an influence of stomatal regulation and transpiration. The size and quantity of fungal associated lipid bodies suggested a role of carbon storage and management within the ecosystem.}, author = {J.R. Barrow and Aaltonen, R.E.} } @conference {50810, title = {The progression of shrub encroachment into a desert grassland in southern New Mexico from 1936-2003}, booktitle = {2003 Fall Meeting, American Geophysical Union}, year = {2003}, month = {December 8-12, 2}, pages = {F335}, address = {San Francisco, CA}, abstract = {Woody plant encroachment into arid and semiarid grass-dominated landscapes has been noted in many parts of the Southwestern United States. This shrub advance has been observed on both the USDA-ARS Jornada Experimental Range (JER) and the adjacent New Mexico State University Chihuahuan Desert Rangeland Research Center (CDRRC) in southern New Mexico using varying ground survey techniques extending back to 1858. These two experimental ranges have also been imaged numerous times using aerial photography (and recently with high resolution commercial satellites) starting with USDA flights in the 1930{\textquoteright}s. Since 1936, 37 separate aerial photography missions have been flown over parts of JER/CDRRC. Because rangeland remediation treatments are common in the Jornada Basin, it is difficult to find areas where no treatments, especially herbicide applications, have been employed to arrest the shrub advance. Aerial photographs were analyzed over Pasture 2 on the CDRRC where no herbicides or other treatments had been applied. There are 22 separate overflight dates covering Pasture 2 from 1936 to 2003. The aerial photos were scanned and digitized to analyze the amount of grass cover and its change over 60+ years. Despite encountering numerous difficulties in analyzing a greatly varying aerial photo data set (including varying resolutions, spectral intervals, moisture conditions, time of year of observation, and appearance of grass cover), the aerial photos provide an invaluable historic record. The grass cover obtained from remote sensing data in Pasture 2 is compared with the less frequent conventional vegetation ground surveys. The changing amounts of grass cover with time are related to various outside factors, such as persistent drought periods. The rate of shrub advance across Pasture 2 has a direct influence on changes in the water, carbon, and energy cycles of these arid lands.}, author = {A. Rango and Andrea S. Laliberte and S. Tartowski and Kris Havstad and Gibbens, Robert P. and Joel R. Brown and Reldon F. Beck} } @conference {50828, title = {Plant ecophysiological processes and soil water availability in semiarid and arid regions}, booktitle = {Society for Range Management, New Mexico Section, Winter Meeting}, year = {2003}, month = {January 21-23, 2}, pages = {2}, address = {Albuquerque, NM}, abstract = {The goal of this contributed paper was to demonstrate how determination of plant water source use through use of natural abundance stable isotopic tracer techniques has applications in riparian areas and on rangelands. Research was presented that determined what sources of water different plant species are using and how this varies spatially, due to differences in soil texture and geomorphology, and how this varies temporally, due to seasonally climate patterns. This knowledge is applicable to remediation and monitoring efforts because it provides information to land managers on what sources of water are available on different landscapes and what plant species will be capable of exploiting these water sources for biomass production. This research is also applicable to understanding how changes in the management of vegetation and hydrology interact on the landscape and result in different patterns of community structure.}, author = {K. A. Snyder} } @article {50838, title = {Phosphorus solubilization and uptake by dark septate fungi in fourwing saltbush, Atriplex canescens (Pursh) Nutt.}, journal = {Journal of Arid Environments}, volume = {51}, year = {2002}, month = {July 1, 2002}, pages = {449-459}, abstract = {Fourwing saltbush, Atriplex canescens (Pursh) Nutt., is an ecologically important range plant in arid southwestern USA rangelands. Native populations of this non-mycorrhizal, chenopodiacious shrub are extensively colonized by melanized dark septate fungi (DS). Seedling radicles of A. canescens are colonized at germination by a DS fungus identified as Aspergillus ustus that cannot be removed by heat or sterilization. The mutualistic association of A. canescens and A. ustus was evaluated by comparing plants treated with either no P (0P) or adequate plant available soluble P (30 ppm) in the root zone (AAP). Plant unavailable P (as rock phosphate (RP) or tricalcium phosphate (TCP)) was separated from the roots by a barrier that only allowed the passage of fungi. Plant roots in all treatments were internally colonized by A. ustus. A significant mutualistic response was observed in the RP and TCP treatments. Evidence for enhanced P uptake by the plant via the fungus was greater shoot and root biomass production and fungal density. Plants receiving P from plant unavailable P from TCP below the barrier via the fungus had equivalent shoot biomass and greater root biomass (P< 0.01) than plants receiving soluble P (AAP). Phosphorus use efficiency was increased in plants supplied P by fungi from plant unavailable P treatments. It was concluded that A. ustus utilized plant carbon for growth and the solubilization, uptake and transport of P to enhance shoot and root biomass. The potential benefits of DS fungi in arid ecosystems is discussed.}, keywords = {Atriplex canescens, fourwing saltbush, phosphorus solubilization, plant carbon, potential benefits}, url = {/files/bibliography/02-001.pdf}, author = {J.R. Barrow and Avila-Osuna, P.} } @article {50874, title = {Potential environmental controls on nitrogenase activity in biological crusts of the northern Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {52}, year = {2002}, note = {//NMSU, USDA//LTER IV//}, month = {2002}, pages = {293-304}, abstract = {

We used the acetylene reduction assay to analyse soil nitrogenase activity at the Jornada Long-Term Ecological Research site (northern Chihuahuan Desert, New Mexico, U.S.A.). A three-day irrigation and fertilization experiment showed that water and carbon (glucose) enhanced nitrogenase activity, while NH4NO3 reduced activity. Micronutrient (Mo, Fe, Co) and phosphorus fertilization had no significant effect. A survey of Jornada Basin soils did not reveal an inverse relationship between nitrogenase activity and the ratio of available nitrogen (N) to phosphorus (P), as hypothesized; however, the highest rates of nitrogenase activity were detected in tarbush floodplain soils with a low ratio of available N to P. These findings suggest that labile carbon and inorganic N may exert a stronger control on nitrogenase activity than phosphorus or micronutrient levels.

}, keywords = {article, articles, journal, journals, nitrogenase activity, soil crust, biological}, doi = {10.1006/jare.2002.1007}, url = {files/bibliography/21-013.pdf}, author = {Anne E. Hartley and W. H. Schlesinger} } @inbook {50877, title = {Productivity and Desertification}, booktitle = {Encyclopedia of Soil Science}, year = {2002}, month = {August 13, 2002}, pages = {340-342}, publisher = {Marcel Dekker, Inc.}, organization = {Marcel Dekker, Inc.}, abstract = {Rangeland degradation frequently occurs in desert environments throughout the world. Although productivity in desert rangelands is 1 to 3 orders of magnitude lower than in forest ecosystems, desert rangelands cannot be viewed as either simple or unproductive systems. Productivity is strongly coupled to precipitation, but nutrients and their availability strongly regulate both primary and secondary production. Degradation of desert grasslands is often characterized by replacement of perennial herbaceous species by long-lived woody shrubs and by an associated reduction in the capacity of the ecosystem to perform some functions. These reductions may be irreversible on human time scales. Numerous causes have been proposed for this grassland-to-shrubland transition including overgrazing, exclusion of fire, dispersal of seeds of woody species by herbivores and a combination of natural and anthropogenic stressors. It is not likely that the historical effects of any one factor can be clearly and singularly associated with desert grassland degradation. We can not necessarily differentiate between cases in which certain stressor(s) are directly responsible for changes and cases in which they simply facilitate the transition from a community that evolved under a previous climatic regime to one that is better adapted to current conditions. It is now understood that these changes can be long-lived, non-linear and resistant to remediation. The dynamics of desert rangeland degradation have been conceptualized for the Chihuahuan Desert of North America. Allogenic forces contributed to reductions in herbaceous cover and to increased dispersal of seeds of competitive woody species. Autogenic forces then reinforced spatial redistribution patches.}, url = {/files/bibliography/02-098.pdf}, author = {Kris Havstad} } @article {50900, title = {Presence/absence of a keystone species as an indicator of rangeland health}, journal = {Journal of Arid Environments}, volume = {50}, number = {3}, year = {2002}, month = {March 1, 2002}, pages = {513-519}, abstract = {

We examined the relationship between a Chihuahuan Desert grassland keystone species (banner-tailed kangaroo rat, Dipodomys spectabilis) and several vegetation and soil indicators of rangeland health in order to define a threshold indicator value for irreversible change in ecosystem structure and function. The abundance of occupied and/or abandoned D. spectabilis burrow-mounds was assessed at 117 sites in south central New Mexico where previous studies had reported vegetation cover and composition. The most robust indicator for presence/absence of D. spectabilis was shrub cover. D. spectabilis did not occur at sites with shrub cover greater than 20\%. It was concluded that a threshold value of 20\% shrub cover could be applied to assessment and monitoring of Chihuahuan Desert rangelands because higher shrub cover results in the local extinction of this keystone species. The combination of data on the presence/absence of a keystone species with vegetation and soil indicators provides a method for identifying thresholds of degradation that may be irreversible.

}, keywords = {banner-tailed kangaroo rat, Chihuahuan Desert, degradation threshold, desertification, Dipodomys spectabilis, environmental indicators}, doi = {10.1006/jare.2001.0900}, url = {files/bibliography/02-JAE-Whitford.pdf}, author = {Krogh, S.N. and Zeisset, M.S. and E. Jackson and Walter G. Whitford} } @article {50926, title = {Plant species dominance at a grassland-shrubland ecotone: An individual-based gap dynamics model of herbaceous and woody species}, journal = {Ecological Modelling}, volume = {152}, number = {1}, year = {2002}, month = {June 1, 2002}, pages = {5-32}, abstract = {

Transition zones or ecotones between biomes are predicted to be particularly sensitive areas to directional changes in climate. However, for many ecotones, there is little understanding of the key processes that allow dominant species from adjacent biomes to coexist at transition zones and how differences in these processes affect species responses to changes in environmental conditions. The objective of this study was to examine the relationship between plant life history traits and patterns in dominance and composition at a grassland{\textendash}shrubland transition zone in order to predict shifts in dominance with directional changes in climate. It was hypothesized that differences in life history traits allow species from adjacent biomes to coexist at this transition zone, and that these dominance patterns are dynamic through time as a result of species-specific responses to changes in climate. A mixed lifeform individual plant-based gap dynamics model (ECOTONE) was developed to examine consequences of differences in recruitment, resource acquisition, and mortality to patterns in species dominance and composition under a variety of soils and climatic conditions. This model is unique because it represents interactions among multiple potential dominant species that include congeneric species of one lifeform as well as herbaceous and woody lifeforms across multiple spatial scales. Similar to other gap models, ECOTONE simulates the recruitment, growth, and mortality of individual plants on a small plot through time at an annual timestep. ECOTONE differs from other gap models in the degree of detail involved in determining successful recruitment by each species and in the simulation of belowground resources. Individual plant root distributions and resource availability by depth are dynamic. Soil water content is simulated on a daily timestep and nitrogen is simulated monthly. Multiple spatial scales can be simulated using a grid of plots connected by seed dispersal. ECOTONE was parameterized for two soil types at the Sevilleta National Wildlife Refuge (SEV), a site located within the transition zone between two major biomes in North America. Shortgrass steppe communities are dominated by the perennial grass Bouteloua gracilis (blue grama) and Chihuahuan desert communities are dominated by the perennial grass Bouteloua eriopoda (black grama) or the shrub Larrea tridentata (creosotebush). Experiments were conducted to provide key parameters related to recruitment and growth that were supplemented with information from the literature for remaining parameters. Model output was verified using field estimates of cover and biomass for the three dominant species as well as other groups of species. Simulation analyses were conducted under current climate and for a directional change in climate. Nitrogen was assumed constant for all runs to allow a focus on water availability constraints as affected by climate. Under current climatic conditions, simulated biomass on sandy loam soils was dominated by B. eriopoda with smaller biomass of B. gracilis and other species groups. By contrast, simulated biomass on a loamy sand soil was codominated by B. eriopoda and L. tridentata with very small biomass attributed to other species groups. Under a GFDL climate change scenario of increased year-round temperatures and increased summer precipitation, vegetation patterns shifted to a clear dominance of biomass by B. eriopoda on both soil types. These results show that temporal partitioning of soil water is important to codominance by the two Bouteloua species, and that spatial and temporal partitioning of soil water is important for grass{\textendash}shrub interactions. The results also suggest that global climate change may provide a mechanism for the recovery of B. eriopoda following shrub invasion in the Southwestern U.S. Thus, an individual-based modeling approach is capable of representing complex interactions among herbaceous and woody species as well as between congeneric species with different life history traits at a biome transition zone. This modeling approach is useful in improving our understanding of key processes driving these vegetation dynamics as well in predicting shifts in dominance as environmental conditions change in the future.

}, keywords = {Bouteloua species, Chihuahuan Desert, climate change, creosotebush, ECOTONE, shortgrass steppe}, doi = {10.1016/S0304-3800(01)00460-4}, url = {files/bibliography/JRN00362.pdf}, author = {Debra C. Peters} } @article {50959, title = {Phylogeographic structure in the bogus yucca moth Prodoxus quinquepunctellus (Prodoxidae): Comparisons with coexisting pollinator yucca moths}, journal = {Molecular Phylogenetics and Evolution}, volume = {21}, number = {1}, year = {2001}, note = {//USDA//LTER IV//Entered 1/6/06}, month = {2001}, pages = {117-127}, abstract = {

The pollination mutualism between yucca moths and yuccas highlights the potential importance of host plant specificity in insect diversification. Historically, one pollinator moth species, Tegeticula yuccasella, was believed to pollinate most yuccas. Recent phylogenetic studies have revealed that it is a complex of at least 13 distinct species, eight of which are specific to one yucca species. Moths in the closely related genus Prodoxus also specialize on yuccas, but they do not pollinate and their larvae feed on different plant parts. Previous research demonstrated that the geographically widespread Prodoxus quinquepunctellus can rapidly specialize to its host plants and may harbor hidden species diversity. We examined the phylogeographic structure of P. quinquepunctellus across its range to compare patterns of diversification with six coexisting pollinator yucca moth species. Morphometric and mtDNA cytochrome oxidase I sequence data indicated that P. quinquepunctellus as currently described contains two species. There was a deep division between moth populations in the eastern and the western United States, with limited sympatry in central Texas; these clades are considered separate species and are redescribed as P. decipiens and P. quinquepunctellus (sensu stricto), respectively. Sequence data also showed a lesser division within P. quinquepunctellus s.s. between the western populations on the Colorado Plateau and those elsewhere. The divergence among the three emerging lineages corresponded with major biogeographic provinces, whereas AMOVA indicated that host plant specialization has been relatively unimportant in diversification. In comparison, the six pollinator species comprise three lineages, one eastern and two western. A pollinator species endemic to the Colorado Plateau has evolved in both of the western lineages. The east\– west division and the separate evolution of two Colorado Plateau pollinator species suggest that similar biogeographic factors have influenced diversification in both Tegeticula and Prodoxus. For the pollinators, however, each lineage has produced a monophagous species, a pattern not seen in P. quinquepunctellus. \© 2001 Academic Press

}, keywords = {article, insect, Tegeticula, insect, yucca moth, insect,population ecology, journal, pollination mutualism, yucca moth, pollination, yucca moth, yucca moth, Tegeticula, Yucca, pollination, Yucca, Prodoxus, Yucca, reproduction, Yucca, yucca moth}, url = {doi:10.1006/mpev.2001.0995, available online at http://www.idealibrary.com}, author = {David M. Althoff and Groman, Joshua D. and K. A. Segraves and Pellmyr, Olle} } @article {50987, title = {Pen confinement of yearling ewes with cows or heifers for 14 days to produce bonded sheep}, journal = {Small Ruminant Research}, volume = {40}, year = {2001}, month = {June 1, 2001}, pages = {291-297}, abstract = {

Mixed species stocking uses forage resources more efficiently when compared to single species stocking, especially in pastures having complex assemblages of forage species. When mixed species (sheep and cattle) remain consistently as a cohesive group (flerd), predation risks are lessened and fencing and herding costs are reduced. To maintain a cohesive egroup, a 30-day bonding period is recommended in which young sheep and bovine pairs are penned together. This research tested if pen confinement can be reduced from 30 to 14 days, reducing feed, labor and overhead costs. Sixteen mature cows (7 to 8 years of age) and 16 9-month-old heifers were randomly paired with 1 of 32 yearling ewe lambs. Eight cow/ewe (PC) and eight heifer/ewe (PH) pairs were maintained individually in 2mx6m pens for 14 days. The other eight-cow/ewe (NC) and heifer/ewe (NH) pairs were separated by species with each species maintained on separate pastures for 14-day period. After 14 days, pairs were released in observation paddocks and separation distances between treatment pairs were measured during a 30-minute open field test. Separation distance did not differ (P=0.973) between the PC and PH treatments; however, separation distance for NC vs NH, NC versus PC, and NH vs PH all differed. Mean separation distance (meters) and standard errors were 40+/-3.9, 3+/-0.3, 76+/-5.3, and 4+/-1.4 for CH, PH, CC and PC treatments, respectively. Previously penned animals spent more time grazing and less time walking than nonpenned animals. Cow age was not found important in establishing a bond. These data suggest that an interspecific bond using pen confinement can be formed within 14 days, representing 53\% savings in time and associated costs when compared to confinement lasting 30 days.

}, keywords = {beef cattle, bonded sheep, bonding, cows, heifers, Mixed species stocking, Multispecies stocking, pen confinement, sheep, yearling ewes}, doi = {10.1016/S0921-4488(01)00183-3}, url = {/files/bibliography/01-022.pdf}, author = {E.L. Fredrickson and D.M. Anderson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and M.D. Remmenga} } @article {50989, title = {Particle production and aeolian transport from a "supply-limited" source area in the Chihuahuan desert, New Mexico, United States}, journal = {Journal of Geophysical Research}, volume = {106}, number = {D6}, year = {2001}, note = {//USDA//LTER IV//entered 07/16/2001;correction 08/19/2008}, month = {2001}, pages = {5267-5278}, abstract = {Wind erosion mechanisms were investigated for the "scrape site" at the Jornada Experimental Range near Las Cruces, New Mexico, in the Chihuahuan desert. The scrape site was denuded of vegetation and scraped flat in 1991. We adopted the site in 1994 because it offered an opportunity to study wind erosion mechanisms for a large area of unprotected sandy and crusted soil in an otherwise natural setting and over a period of several years. We installed and operated the following instrumentation for a period of 35 months; three meteorological towers, each 2 m in height, with wind speed sensors at 0.2, 0.5, 1.0, and 2.0 m above ground; air temperature at 0.2 and 2 m height; rain gauge; seven sets of particle collectors at 0.1, 0.5, and 1.0 m heights; and three fast-response particle mass flux sensors at 0.02, 0.1, 0.2, and 0.5 m heights; all along a transect crossing the site and parallel to the predominant southwesterly wind direction. The minimum threshold friction velocity for the scrape site with a thin layer of loose material was 25 cm s-1. This minimum threshold velocity increased to as high as 100 cm s-1 depending on the degree of particle depletion and the site{\textquoteright}s status which varied between supply unlimited just after a high wind episode and supply limited which was more typical for the rest of the time. The dominant mechanism producing fresh sediment for transport was sandblasting of the surface crust. The measurements showed that supply and availability of loose, fine particles on the surface is a strong control of rates of erosion rather than wind energy alone.}, keywords = {aeolian processes, particle production, aeolian processes, Scrape Site, aeolian processes, transport, article, articles, dust emission, journal, journals, soil erosion, wind erosion}, author = {D. E. Gillette and Chen, Weinan} } @conference {51056, title = {A portable rainfall simulator for small paired-plot comparisons}, booktitle = {Soil Science Society of America Annual Meeting}, year = {2001}, note = {CD-ROM not available to create pdf file; no pdf number. August 1, 2001}, month = {October 15, 2001}, pages = {CD-ROM}, abstract = {We describe the design and calibration of an inexpensive rainfall simulator in which a manually operated pulley system is used to move a nozzle along a 3m track, uniformly covering an area of up to 1 x 2.5m. Nozzle heights can be set up to 3m from the ground surface. High or low intensity rainfall events can be simulated using a VeeJet and cone nozzle. The simulator, pump and 500-gallon water tank are transported in a pickup truck. Garden hoses transport water from the tank to the simulator, allowing plots to be located in remote sites. Using a VeeJet nozzle, water distribution within 0.5m2 (70.7 x 70.7cm) plots remained uniform in winds up to 40kph, as long as all sides of the simulator were protected with tarps: the average difference between the highest and lowest rates recorded by 5 gauges in each plot was just 11\% of the mean (n = 23 runs). Cone nozzles produced only slightly less uniform distributions. Nearly 80\% and 55\% of drop sizes sfell between 1 and 3mm for the VeeJet and cone nozzle, respectively. We present equilibrium infiltration rates and sediment production data from experiments designed to quantify disturbance effects based on simultaneous measurements from paired plots.}, author = {Justin Van Zee and Jeffrey E. Herrick} } @article {51058, title = {Persistence of biosolids in a Chihuahuan Desert rangeland 18 years after application}, journal = {Arid Land Research and Management}, volume = {15}, year = {2001}, note = {//?//LTER IV//}, month = {2001}, pages = {223-232}, abstract = {

The experimental application of municipal biosolids to degraded arid and semiarid rangelands has been practiced for many years and is becoming more common in the western United States. Previous studies have examined the effects of applying biosolids to land areas that have been degraded by one or more different factors including overgrazing, fire suppression, and increased drought frequency, duration, or intensity. However,few of these studies have measured the persistence of biosolids in the soil. This study is an attempt to recover information from an abandoned reclamation effort in which municipal biosolids were spread on a degraded rangeland on the Jornada Experimental Range in southern New Mexico. The biosolids were applied in 1979 and were still present in substantial amounts when soil samples were taken in 1997. An estimated 32\% of the applied biosolids persisted as fragments greater than 2 mm in diameter for almost 20 years. There were no apparent benefits of biosolid application at this site in terms of vegetation establishment within the first four years, and there was no correlation between vegetation patterns and the concentration of biosolids remaining in the soil in 1997. It is hypothesized that much of the applied sludge remains in the soil because of the recalcitrant nature of digested biosolids combined with the environmental conditions of soil in and systems. Long-term? results from biosolid addition experiments in and and semiarid rangelands should be considered before the practice is widely, used for reclamation of degraded rangeland sites.

}, keywords = {article, articles, biosolids, Chihuahuan Desert, journal, journals}, doi = {10.1080/15324980152119784 }, url = {files/bibliography/JRN00342_0.pdf}, author = {Walton, M. and Jeffrey E. Herrick and Gibbens, Robert P. and M.D. Remmenga} } @article {51057, title = {Persistence of municipal biosolids in a Chihuahuan Desert rangeland 18 years after application}, journal = {Arid Land Research and Management}, volume = {15}, year = {2001}, month = {January 1, 2001}, pages = {223-232}, abstract = {

The experimental application of municipal biosolids to degraded arid and semi-arid rangelands has been practiced for many years and is becoming more common in the western United States. Previous studies have examined the effects of applying biosolids to land areas that have been degraded by one or more different factors including overgrazing, fire suppression, and increased drought frequency, duration, or intensity. However, few of these studies have measured the persistence of biosolids in the soil. This study is an attempt to recover information from an abandoned reclamation effort in which municipal biosolids were spread on a degraded rangeland on the Jornada Experimental Range in southern New Mexico. The biosolids were applied in 1979 and were still present in substantial amounts when soil samples were taken in 1997. An estimated 32\% of the applied biosolids persisted as fragments greater than 2 mm in diameter for almost twenty years. There were no apparent benefits of biosolid application at this sit in terms of vegetation establishment within the first four years, and there was no correlation between vegetation patterns and the concentration of biosolids remaining in the soil in 1997. It is hypothesized that much of the applied sludge remains in the soil because of the recalcitrant nature of digested biosolids combined with the environmental conditions of soil in arid systems. Long-term results from biosolid addition experiments in arid and semi-arid rangelands should be considered before the practice is widely used for reclamation of degraded rangeland sites.

}, url = {/files/bibliography/01-051.pdf}, author = {Walton, M. and Jeffrey E. Herrick and Gibbens, Robert P. and M.D. Remmenga} } @article {JRN54979, title = {The Potential for Semiarid Community Type Differentiation via Exploitation of the Directional SIgnal: Tests with AVHRR Data}, journal = {IEEE 2000 International Geoscience and Remote Sensing Symposium}, year = {2000}, pages = {1957-1959}, chapter = {1957}, abstract = {

Community-level vegetation type differentiation is regarded as an important application of remote sensing in monitoring the health of semiarid environments and yet it has proved difficult to discriminate more than two or three community types with confidence when using coarse spatial resolution data from off-nadir scanning sensors such as the AVHRR, even when multi-temporal datasets are used.
Attempts to relate vegetation phenology to community typeusing AVHRR data have produced mixed results and large classification errors have been attributed to subpixel scale topographc and soil background variations, lack of in-flight calibration, inaccurate reflectance retrieval and poor registration. While these are important factors, anisotropy in surface reflectance as a result of the bidirectional reflectance distribution function (BRDF) also causes severe perturbations in the signal and yet this is rarely accounted for adequately. Recent years have seen a wider acknowledgement of this fundamental aspect of optical remote sensing, although it is
usually approached as a problem. The extent of the improvement in community type differentiation may be considerable when a BRDF model is used to separate isotropic and anisotropic components. Here this potential is tested using data from the AVHRR over semi-arid regions.

}, url = {files/bibliography/Rango2000-04.pdf}, author = {M. Chopping and A. Rango and Jerry Ritchie} } @article {51069, title = {Potential growth and drought tolerance of eight desert grasses: lack of a trade-off?}, journal = {Oecologia}, volume = {123}, number = {1}, year = {2000}, note = {//NMSU,USDA//LTER III//updated keywords 4/7/2009; pdf available}, month = {2000}, pages = {90-98}, abstract = {

Eight perennial C-4 grasses from the Jornada del Muerto Basin show 5-fold differences in relative growth rates under well-watered conditions (RGRmax). In a controled environment, the hypothesis was tested that there is an inverse relationship (trade-off) between RgRmax and the capacity of these species to tolerate drought. Based on these controlled-environment results, it is hypothesized that the commonly reported correlation between plant growth potential and drought tolerance in the field may in some cases be explained by differential effects of plants on soil-water content rather than by differences in species responses to drought.

}, keywords = {article, articles, C-4, drought tolerance, grass, grass, drought tolerance, journal, journals, photosynthetic pathway, plant, Aristida purpurea, plant, Bouteloua eriopoda, plant, Eragrostis lehmanniana, plant, Hilaria mutica, plant, Muhlenbergia porteri, plant, Panicum obtusum, plant, Scleropogon brevifolius, plant, Sporobolus flexuosus, water stress, xerophytism}, doi = {10.1007/s004420050993 }, url = {files/bibliography/JRN00310.pdf}, author = {Roberto J. Fern{\'a}ndez and J. F. Reynolds} } @proceedings {51078, title = {Protected areas management and research: Complement or conflict?}, year = {2000}, month = {January 23-25, 2}, pages = {1-9}, address = {Abu Dhabi, United Arab Emirates}, abstract = {

Land areas designated as research sites and those designated as protected areas can share similar potential problems and basic needs. Both types of land uses require varying levels of management. In neither case can management be viewed as a passive activity. Though protected areas may not require large spatial scale manipulations or intensive inputs characteristic of research sites, these areas can not be managed simply as "islands" within surrounding landscapes of differing land uses. For example, protected areas can be impacted by numerous disturbances that originate off-site. In this sense, management of protected areas requires knowledge and technologies applicable to its local environment. In addition, management of protected areas requires technically skilled science-based personnel. A research program embedded within a protected area can synergistically service the knowledge and personnel needs required for land management. More importantly, an active research program can provide relevant information to users of land surrounding protected areas. Technology transfer activities resulting from on-site research can improve community-based support for protected areas and improve adoption of conservation practices.

}, keywords = {conservation practices, protected areas management, research sites, technology transfer}, url = {/files/bibliography/726.pdf}, author = {Kris Havstad} } @conference {51101, title = {Plant species dominance and disturbance at a grassland-shrubland ecotone}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {175}, address = {Snowbird, UT}, abstract = {The objective of this study was to evaluate the role of presence and identity of dominant species on vegetation patterns at a shortgrass steppe- Chihuahuan desert ecotone. Species removals were conducted: (1) to identify new dominant species and assemblages after the current dominant is removed, and (2) to determine if dominant species with different life history traits shave different legacy effects on recovery of other species through time. This study was conducted at the Sevilleta LTER in central New Mexico where communities may be dominated or codominated by one of two perennial grasses (blue grama, black grama) and one shrub (creosotebush). Within each community, all plants of the dominant species were removed from within 5 3m x 4m plots in 1995, and have been removed annually since that time. Five control plots were also located at each site. Cover and density by species have been estimated annually since 1995. Annuals dominated all removal plots one year after removals were initiated. Subsequent recovery patterns depended upon the dominant species removed. Blue grama removal resulted in establishment and growth of perennial forbs whereas removal of black grama promoted recovery by perennial grasses. Removal of creosotebush in mixed communities with black grama resulted in recovery by perennial forbs, grasses, and shrubs whereas removal of this species in shrub-dominated communities resulted in little change in the vegetation. Legacy effects were most important in the first few years after removals were initiated. These results indicate that removal of dominant species by disturbances have dramatic effects on vegetation patterns that may alter the landscape mosaic at this arid-semiarid ecotone.}, keywords = {disturbance, ECOTONE, grassland, plant species dominance, Sevilleta LTER, shrubland}, author = {Debra C. Peters} } @conference {51102, title = {Plant-soil feedbacks and recruitment constraints on perennial grass recovery following shrub invasion}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {372}, address = {Snowbird, UT}, abstract = {Recent climate change simulation analyses predict an expansion of Chihuahuan Desert grasslands and reduction in shrublands in the southwestern U.S. Our objective is to evaluate the importance of plant life history traits and soil development processes to responses of these ecosystems. We are using a spatially interactive gap dynamics model (ECOTONE) to predict vegetation responses for a variety of initial soil conditions, from well-structured soils with relatively high soil organic matter to highly degraded soils. Our model includes feedbacks between soil organic matter, water availability, plant recruitment, and growth. We are simulating sites located throughout the Chihuahuan Desert including the SEV-LTER and JER-LTER. We are also examining the importance of seed dispersal to the recovery of perennial grasses. Our results show that recovery at the landscape scale is highly heterogeneous and depends both on nthe initial vegetation and soil properties, as well as the modification of these properties through time due to plant-soil feedbacks. Recruitment is more important than plant growth in determining grass response. Recovery is also affected by climate interacting with vegetation and soil properties. Our plans include expanding the spatial component of the model to include the redistribution of water, soil, and nutrients across the landscape.}, keywords = {ECOTONE, perennial grass, predict, recovery, seed dispersal, shrub invasion}, author = {Debra C. Peters and Jeffrey E. Herrick} } @article {51123, title = {Plot-scale studies of vegetation, overland flow and erosion interactions: case studies from Arizona and New Mexico}, journal = {Hydrological Processes}, volume = {14}, year = {2000}, note = {//NMSU//LTER III//entered 04/17/2007; udpated 07/28/2008}, month = {2000}, pages = {2921-2943}, abstract = {

Rainfall-simulation experiments have been carried out on a series of plots ranging in size from 1 m2 to c 500 m2 in order to observe process and flux-rate changes resulting from the replacement of the dominant vegetation type from grassland to shrubland in the southwest. Results have demonstrated variations in infiltration rates, flow, hydraulics, splash and interrill erosion rates and nutrient transport rates. Furthermore, the shrubland areas develop rills, which are responsible for significant increases in overall erosion rates. The small-plot experiments allow the definition of controlling factors on the processes, and highlight the importance of vegetation controls. Although the small-plot approach has a number of significant advantages, it also has a number of disadvantages, which are discussed in detail. Some of these problems can be overcome with a careful consideration of experimental design. It is argued that plot-scale studies play an important part in improving our understanding of complex, open systems, but need to be integrated with other approaches such as the monitoring of natural events and computer modelling so that mutually consistent understandings of complex, ecohydrological systems can be achieved.

}, keywords = {article, articles, erosion, interrill, erosion, raindrop, erosion, splash, hydrology, ecosystem dynamics, hydrology, erosion, hydrology, grassland, hydrology, natural runoff, hydrology, nutrient transport, hydrology, overland-flow hydraulics, hydrology, processes, hydrology, raindrop processes, hydrology, rainfall simulation, hydrology, rills, hydrology, sediment transport, hydrology, shrubland, hydrology, soil infiltration, hydrology, Walnut Gulch, hydrology,infiltration, journal, journals, rainfall simulation, erosion, rainfall simulation, grasslands, rainfall simulation, infiltration, rainfall simulation, nutrient transport, rainfall simulation, shrubs}, doi = {10.1002/1099-1085(200011/12)14:16/17<2921::AID-HYP127>3.0.CO;2-7}, url = {files/bibliography/JRN00309.pdf}, author = {John Wainwright and A.J. Parsons and Athol D. Abrahams} } @article {51125, title = {Pollen competition in a natural population of Cucurbita foetidissima (Cucurbitaceae)}, journal = {American Journal of Botany}, volume = {87}, number = {4}, year = {2000}, note = {//NMSU//NONE// entered 03/23/2009; PDF available}, month = {2000}, pages = {527-532}, abstract = {The pollen competition hypothesis predicts that when the number of pollen grains deposited onto stigmas exceeds the number of ovules, selection can operate in the time frame between deposition and fertilization. Moreover, because of the overlap in gene expression between the two phases of the life cycle, selection on microgametophytes may alter the resulting sporophytic generation. The extent to which pollen competition occurs in nature has been unclear, because tests of the predictions of the pollen competition hypothesis have used cultivars and/or artificial growth conditions and hand-pollination techniques. In this study we used a wild species, Cucurbita foetidissima, in its natural habitat (southern New Mexico) to determine the amount and timing of the arrival of pollen onto stigmas, the relationship between pollen deposition and seed number, and the effects of the intensity of pollen competition on progeny vigor. We found that ~900 pollen grains are necessary for full seed set and that a single visit by a pollinator results in the deposition of 653.0 \± 101.8 pollen grains. About 29\% of the flowers receiving a single pollinator visit had 900 or more pollen grains on its stigma. Moreover, within 2 h or anthesis, \>4000 pollen grains were deposited onto a typical stigma, indicating that multiple pollinator visits must have occurred. Fruits produced by multiple visits had greater seed numbers (206 vs. 147) than fruits produced by a single visit. Finally, the progeny produced by multiple pollinator visits were more vigorous than those produced by single visits with respect to five measures of vegetative growth (MANCOVA, Wilks\&$\#$39; lambda = 0.96, F6.370 = 2.54, P\< 0.02. these data demonstrate that conditions for pollen competition exist in nature and support the prediction that pollen competition enhances offspring vigor.}, keywords = {article, journal, plant, Cucurbita, plant, Cucurbitaceae, plant, pollen, plant, pollen competition}, url = {http://www.jstor.org/stable/2656596}, author = {Winsor, James A. and Peretz, Shani and Stephenson, Andrew G.} } @article {51126, title = {A preliminary assessment of regional scale carbon stocks and fluxes of a desert using field measurements, satellite images and model simulations}, year = {2000}, note = {//USDA//LTER IV// Listed in LTER IV 2004 annual report}, month = {2000}, pages = {107}, institution = {U.S. Forest Service, Raleigh NC}, keywords = {book, books, chapter, chapters, model, remote sensing, remote sensing, carbon, remote sensing, ecosystem health, remote sensing, model simulations, remote sensing, vegetation, report, reports}, author = {Zhan, X. and William P. Kustas and A.N. French and Jerry Ritchie and J.H. Prueger and Lawrence E. Hipps and A. Rango and T. J. Schmugge and B. Nolen and M. Chopping} } @proceedings {51155, title = {People and rangeland biodiversity - North America}, volume = {2}, year = {1999}, month = {July 17-23, 1999}, pages = {634-638}, address = {Townsville, Australia}, abstract = {

Biological diversity refers to life at all levels of organization, from genes within populations to the global arrays of species (Wilson 1992). It is often assumed, though, that any discussion of biodiversity is focused at the species level. However, this discussion is still highly complex given that we know only a small percentage of the total microbial, plant, and animal species. Though estimates of microbial, plant, and animal species are as imprecise as between 5 and 50 million (Tilman 1999), there are many arguments for conserving biodiversity. For rangeland management, the concept of biological diversity is typically focused on plant species richness, evenness, and heterogeneity at community-level spatial scales (West 1993). Species diversity is clearly a major determinant of many ecological processes, especially those related to resilience and resistance (Tilman 1998). Given that over 75\% of the earth{\textquoteright}s ecosystems are manipulated for human purposes (Moguel \& Toledo 1999), maintaining abilities of these systems to buffer (resistence) and recover from disturbances (resilience) is key to conserving inherent ecological functions (Peterson et al. 1998). For example, one consequence of species loss is a limit to the potential ways an ecosystem can reorganize following disturbance, an important component of ecosystem resilience (Peterson et al. 1998). It is well recognized that we are currently in the midst of the sixth major period of extinction on earth and that this current extinction period is biologically driven (Chapin et al. 1998). The potential for significant impacts on ecosystem functions due to losses of biodiversity is large and immediate.

}, url = {/files/bibliography/659.pdf}, author = {Kris Havstad and Debra C. Peters} } @article {51165, title = {Preliminary results from reseeding degraded Dera Ghazi Khan rangeland to improve small ruminant production in Pakistan}, journal = {Small Ruminants Research}, volume = {32}, number = {1}, year = {1999}, month = {March 1, 1999}, pages = {43-49}, abstract = {

Thatta Leghari rangeland in the Dera Ghazi Khan district of Pakistan covers an area of 1004\ ha. Its topography is undulating, soil is calcareous and low in organic matter and supports a native standing crop of mainly unpalatable herbaceous vegetation. Due to uncontrolled grazing the range has degraded from its productive potential. Between 1992 and 1993 the native range (1004\ ha) was not grazed. Then in 1992 and 1993, a 600\ ha area was reseeded with two introduced grasses, Gorkha (Lasiurus sindicus) and Buffel grass (Cenchrus ciliaris). Forage production on both the reseeded and native range was measured in 1992 and 1993 at the end of the growing season during October. Weather during these 2 years reflected the long term mean conditions with respect to temperature and distribution of precipitation. The reseeded area produced 10 times (4000\ kg/ha) more forage than the native range (425\ kg/ha) in 1992 and more than twice the forage (1250\ kg/ha vs 534\ kg/ha) in 1993, a year with 37\ mm less total rainfall. Proximate analysis of the forage harvested in 1993 was determined for both treatments. Buffel grass was higher in crude protein (7.8\%) than Gorkha (6.2\%) and chimber (5.9\%; Eleusine flagellifera) a native grass. The native shrub, lana (Salsola foetida) had a higher energy value, 2.7\ Mcal/kg, than all of the other species. Daily goat and sheep diets consisted of 51\% and 32\% shrub, respectively, with grasses comprising the remainder. Forbs composed 35\% of the sheep diet whereas, shrubs (51\%) dominated the goat diets on the reseeded rangeland. Liveweight gain differed (p\<0.05) between goats (34\ g/day) and sheep (14\ g/day). These preliminary results indicate that reseeding may be an important intervention for Pakistan rangeland improvement, for improving nutrition for small ruminants.

}, keywords = {behavior, forage species, Pakistan, rangeland, reseeding, Sheep and goat}, doi = {10.1016/S0921-4488(98)00157-6}, url = {/files/bibliography/668.pdf}, author = {Khan, M.F. and D.M. Anderson and Nutkani, M.I. and Butt, N.M.} } @conference {51166, title = {Plant species associations with different patch types at a semiarid-arid grassland ECOTONE}, booktitle = {5th World Congress, International Association for Landscape Ecology}, volume = {I (A-K)}, year = {1999}, month = {July 29-August 3}, pages = {85-86}, address = {Snowmass Village, Colorado}, abstract = {The objective of this study was to investigate the relationship between subordinate species and the mosaic of dominant grasses at a semiarid-arid grassland ecotone and to compare these localized patterns of species to their geographic range. In central New Mexico, USA, a biome transition zone occurs where Bouteloua gracilis, the dominant of the shortgrass steppe, and Bouteloua eriopoda, the dominant in Chihuahuan Desert grasslands dominate. We used a multiple scale (0.25-256 m2) design to sample species occurrence in 60 patches dominated by either of these two grasses (30+30). Patches of the two types were interspersed across the landscape within a 1500ha area. Soil samples (0-20cm) were collected to test the hypothesis that soil texture controls the distribution of the dominant grasses. Patches dominated by B. gracilis had soils with significantly higher clay content relative to the other patch type. Of the 44 species with sufficient frequency for statistical analyses, 15 were associated with B. gracilis dominated patches, and 10 with B. eriopoda dominated ones. These two sets of species did not clearly differ in their geographic distributions. Our results indicate that this transitional mosaic is composed of patches with different species composition but it is not a mosaic of the interacting biomes.}, author = {G. Kroel-Dulay and Odor, P. and Debra C. Peters} } @inbook {51191, title = {Plants and water in drylands}, booktitle = {Eco-hydrology}, year = {1999}, note = {//?//LTER III//ProCite field[6]: In}, month = {1999}, pages = {78-126}, publisher = {Routledge}, organization = {Routledge}, address = {London}, abstract = {

It could be argued that the understanding of eco-hydrological processes is critical in drylands for two reasons. First, in most cases the aridity of the dry lands means that the supply of water is the dominant control on the growth and maintenance of plants. Second, most drylands are characterised by extreme variability in water availability. Plants must adapt to use this variable source. In addition, large amounts of soil erosion during storm events can remove the uppermost, relatively fertile and moisture-retaining parts of the soil profile and thus enhance the importance of moisture availability as the dominant control on dry land vegetation. In this chapter, we will explore these interrelationships and feedback mechanisms at a number of spatial and temporal scales. In doing so, we have divided the material into three major sections.

}, keywords = {book, books, chapter, chapters, plant, water, report, reports, water, plant}, doi = {10.4324/9780203980095 }, author = {John Wainwright and Mulligan, M. and J. Thornes}, editor = {Baird, A. J. and Wiley, L. (eds.)} } @article {51202, title = {Predicting sediment transport by interrill overland flow on rough surfaces}, journal = {Earth Surface Processes and Landforms}, volume = {23}, year = {1998}, note = {//NONE//LTER III//}, month = {1998}, pages = {481-492}, abstract = {

Modeling soil erosion requires an equation for predicting the sediment transport capacity by interrill overland flow on rough surfaces. The conventional practice of partitioning total shear stress into grain and form shear stress and predicting transport capacity using grain shear stress lacks rigor and is prone to underestimation. This study therefore explores the possibility that inasmuch as surface roughness affects flow hydraulic variables which, in turn, determine transport capacity, there may be one or more hydraulic variables which capture the effect of surface roughness on transport capacity sufficiently well for good predictions of transport capacity to be achieved from data on these variables alone. To investigate this possibility, regression analyses were performed on data from 1506 flume experiments in which discharge, slope, water temperature, rainfall intensity, and roughness size, shape and concentration were varied. The analyses reveal that 89.8 per cent of the variance in transport capacity can be accounted for by excess flow power and flow depth. Including roughness size and concentration in the regression improves that explained variance by only 3.5 per cent. Evidently, flow depth, when used in combination with excess flow power, largely captures the effect of surface roughness on transport capacity. This finding promises to simplify greatly the task of developing a general sediment transport equation for interrill overland flow on rough surfaces. {\textcopyright}1998 John Wiley \& Sons, Ltd.

}, keywords = {article, articles, hydrology, model, hydrology, sediment transport, journal, journals, model,sediment yields}, doi = {10.1002/(SICI)1096-9837(199812)23:12<1087::AID-ESP934>3.0.CO;2-4}, url = {files/bibliography/JRN00261.pdf}, author = {Athol D. Abrahams and Gary Li and Krishnan, Chitra and Atkinson, Joseph F.} } @article {51203, title = {Pro-active livestock management--Capitalizing on animal behavior}, journal = {Journal of Arid Land Studies}, volume = {7S}, year = {1998}, month = {1998}, pages = {113-116}, abstract = {This paper describes a technique for modifying sheep and or goat behavior to reduce canine predation, management time and fencing requirements under mixed-species stocking. Procedures to modify behavior of individual animals are outlined. The concept involves bonding small ruminants to cattle to produce a cohesive group termed a flerd. A flerd acts as a single interdependent cohesive livestock unit under free-ranging conditions rather than as distinct flocks and herds coexisting in the same area.}, keywords = {behavior, canine predation, herds, livestock}, url = {/files/bibliography/98-002.pdf}, author = {D.M. Anderson} } @article {51216, title = {Perspectives on desertification: Southwestern United States}, journal = {Journal of Arid Environments}, volume = {39}, year = {1998}, month = {1998}, pages = {191-207}, abstract = {

Several climatic changes occurred in the northern Chihuahuan Desert and other parts of the southwest United States during the last 12,000 years leading to a markedly warmer and drier climate.\  Vegetation changed in response to this climatic shift. Generally, this transition was from coniferous woodland to grasslands and eventually to the present day desert scrub.\  Pre-Columbian inhabitants of this region adapted by changing from hunter-gatherer to primarily agrarian economics.\  European immigrations into the southwest U.S. beginning in the mid 1500s greatly affected this region.\  The greatest impact occurred after the U.S. Civil war in the 1860s.\  Before that time land use tended to be localized near small agricultural areas, mines, and military installations.\  The post-war range livestock industry expanded dramatically, especially during the 1880s {\textendash} a period of general abuse of arid lands in the region.\  Recognition of this abuse and the deteriorating productivity of the land led to greater government involvement, including establishment of experimental stations and eventually management of the public domain by governmental agencies.\  Fire suppression, mismanaged grazing, changing climatic conditions, loss of soil and increasing atmospheric CO2 concentrations, mainly due to the burning of fossil fuels, are among the probable causes of continued desertification trends\ \  Urban and rural populations, presently technologically isolated from their environment, need to better understand the dynamic nature of their environment.\  A greater degree of co-operation among diverse entities will be crucial.

}, keywords = {Chihuahuan Desert, desertification, Sonoran Desert, south-west United States}, doi = {10.1006/jare.1998.0390}, url = {/files/bibliography/613.pdf}, author = {E.L. Fredrickson and Kris Havstad and Richard E. Estell and P.W. Hyder} } @proceedings {51218, title = {Perennial grass survival response to Russian knapweed soil allelochemicals}, volume = {51}, year = {1998}, month = {1998}, pages = {65-66}, abstract = {

Russian knapweed is an aggressive, noxious weed that dominates areas by forming monocultures. Development of Russian knapweed monocultures can be partly explained by allelopathy. Russian knapweed exudes polyacetylenes from its roots throughout the growing season and these compounds have been shown to inhibit the growth of certain plant species. A field experiment was established to determine the influence of Russian knapweed soil allelochemicals in situ on the seedling growth of lettuce, blue grama, western wheatgrass, prairie junegrass, and sand dropseed. The experiment was a randomized complete block design with 4 replications. Each transect included 10 seedlings of each bioassay species transplanted inside and directly outside a dense stand of Russian knapweed. Seedlings were irrigated over the course of 15 days. Seedling vigor was ranked visually at 3-day intervals. Blue grama survival inside the stand was 30\% less than outside 3 days after the experiment began. Survival of prairie junegrass, the stand, sand dropseed, western wheatgrass, were less inside compared to outside the stand. A greenhouse experiment was also completed to assess allelopathic potential of Russian knapweed infested soils at three soil depths, (0 to 5, 5 to 10, and 10 to 15 cm). The greenhouse experiment was a randomized complete block design with 4 replications. Response variables, including plant height, number of leaves/tillers, and a visual estimate of vigor, were measured at the onset of the experiment and after 1, 3, and 5 weeks. Differences were not detected between the treatments. However, volunteer seedling emergence was significantly lower for soil from inside the stand. The results will be used to develop an allelopathic parameter for a computer simulation model of Russian knapweed invasion dynamics.

}, author = {Grant, D.W. and Beck, K.G. and D.P. Coffin} } @conference {51232, title = {Plant species diversity along a climatic gradient in the southwestern US}, booktitle = {83rd Annual Meeting, Ecological Society of America}, volume = {79}, year = {1998}, month = {1998}, pages = {185}, abstract = {Spatial and temporal variation in plain species diversity results from multiple factors including land use history, disturbance regime and soil characteristics. At the biome level, climate is the main driving factor of species distributions. The objective of this study was to investigate, the change in species richness and diversity in two grassland biomes of the US (the Shortgrass Steppe and the Chiuahuan Desert Grasslands) for sites along a climatic gradient 4x4m quadrats were sampled from a 50 ha area on three sites representing the two biomes and their ecotone. Results show that the total species richness and diversity decreased as the climate became more arid. Furthermore, a marked shift from a predominance of perennial forbs to equal numbers of annual and perennial forbs vas observed with increased aridity. The grasslands on the ecotone between the two biomes supported a diversity similar to the Chihuahuan desert grassland rather than an expected increased diversity relative to the biomes. Our results suggest that different functional groups of species respond more to long versus short term weather conditions.}, author = {G. Kroel-Dulay and Hochstrasser, T. and D.P. Coffin and J. R. Gosz} } @article {51248, title = {Plant-soil interactions in deserts}, journal = {Biogeochemistry}, volume = {42}, year = {1998}, note = {//USDA//LTER-III//}, month = {1998}, pages = {169-187}, abstract = {

Geostatistical analyses show that the distribution of soil N, P and K is strongly associated with the presence of shrubs in desert habitats. Shrubs concentrate the biogeochemical cycle of these elements in "islands of fertility" that are localized benath their canopies, while adjacent barren, intershrub spaces are comparatively devoid of biotic activity. Both physical and biological processes are involved in the formation of shrub islands. Losses of semiarid grassland in favor of invading shrubs initiate these changes in the distribution of soil nutrients, which may promote the further invasion and persistence of shrubs and cause potential feedbacks between desertification and the Earth{\textquoteright}s climate system.

}, keywords = {article, articles, biogeochemistry, calcite, biogeochemistry, calcium carbonate, biogeochemistry,desertification, biogeochemistry,nitrogen, desertification, erosion, geostatistics, journal, journals, nitogen, phosphorus, Prosopis, soil nutrients, soil heterogeneity, soil, aridisols, soil, nutrients}, doi = {10.1023/A:1005939924434 }, url = {files/bibliography/JRN00260.pdf}, author = {W. H. Schlesinger and A. M. Pilmanis} } @conference {51277, title = {Perspectives on desertification: Southwestern United States}, booktitle = {International Symposium Workshop, Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {1997}, pages = {10}, abstract = {Several climatic changes occurred in the northern Chihuahuan Desert and other parts of the southwest United States during the last 12,000 years, leading to a markedly warmer and drier climate. Vegetation also changed in response to the climatic shift. Generally this transition was from coniferous woodland to grasslands and eventually to the present day desert scrub. Pre-Columbian people occupying this region adapted by changing from hunter-gatherer to largely agrarian economies. During this time the level of cooperation among people apparently increased as shown by the formation of pueblos (cities) and greater trade among diverse regions. This increase in cooperation probably resulted as a response to increasing aridity and more frequent droughts. Recent European immigration into the southwest U.S. beginning in the mid 1500s greatly affected this region. The greatest impact occurred after the U.S. Civil War in the 1860s. Before the 1860s land use tended to be localized around small agricultural areas, mines, and military installations. After the war, however, the range livestock industry expanded dramatically, especially in the 1880s. During this time grazing land was viewed as limitless, but as H.L. Bentley stated in 1898, "... grasses were entirely consumed; their roots were trampled into the dust.. ." This period represents a time of general abuse of arid lands in the region. Recognition of the abuse and the deteriorating productivity of the land led to greater government involvement, including establishing experimental stations and eventually managing of the public domain by governmental agencies. Despite improved land management, desertification processes continue. Continued livestock grazing, changing climatic conditions, soil loss, and increasing atmospheric CO2 concentrations (mainly due to the burning of fossil fuels) are among the probable causes of current desertification trends. Urban and rural populations, now technologically isolated from their environment, need to better understand the dynamic nature of their environment and adapt to these conditions to lessen the human influ-snce on the desertification process. A greater degree of cooperation among diverse entities will be crucial.}, author = {E.L. Fredrickson and Kris Havstad and Richard E. Estell and P.W. Hyder} } @article {51317, title = {The potential of laser-induced fluorescence (LIF) spectra of sheep feces to determine diet botanical composition}, journal = {Small Ruminant Research}, volume = {21}, number = {1-2}, year = {1996}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1996. (http://www.sciencedirect.com/science/journal/09214488)}, month = {June 1, 1996}, pages = {1-10}, abstract = {

Laser-induced fluorescence (LIF) peaks near 470 nm ({\textquoteleft}blue{\textquoteright}) and 650 nm ({\textquoteleft}red{\textquoteright}) from sheep feces treated with chloroform (CHCl3) displayed spectral signatures that varied with diet. Fecal samples were obtained rectally over 3 days in a replicated study consisting of four diets (treatments) fed to 16 Polypay and Polypay {\texttimes} Rambouillet lambs (four lambs per treatment). Basal diet consisted of tobosa (Pleuraphis mutica Buckley [formally Hilaria mutica (Buckl.) Benth.] hay with 0\% (control), 10\%, 20\% or 30\% tarbush (Flourensia cernua D.C.) added on a dry matter basis. Feces were dried at 60 {\textdegree}C, treated with chloroform and the extract from both crushed and intact fecal material was then excited by laser input at 355 nm. Tarbush leaves gave LIF only in the blue region of the spectrum. However, tobosa hay and all fecal pellets produced a bimodal LIF spectral distribution with a lower, broader peak feature in the blue region and a narrower well defined taller feature in the red region of the spectrum. Chloroform did not exhibit fluorescence peaks between 400 nm and 800 nm. As tarbush in the diet increased, so did the magnitude of counts in the blue region of the spectrum. The LIF red/blue intensity ratios appear to be more reliable than actual counts in differentiating feces of sheep fed tobosa diets containing differing amounts of tarbush. red/blue ratios decreased (P\< 0.05) linearly (P\< 0.005) for both crushed and intact sheep fecal pellets as the tarbush/tobosa ratio in the diet increased. Inconsistencies in count amplitudes and wavelengths in either one or both regions (red or blue) of the spectrum and in red/blue ratios (especially on Day 3 for crushed fecal samples) are discussed in terms of sample preparation procedures and sampling days. Our results suggest that further testing of the LIF technique is warranted using diets consisting of several species.

}, keywords = {botanical composition, diets, fecal samples, laser-induced fluorescence (LIF), sheep}, doi = {10.1016/0921-4488(95)00817-9}, url = {/files/bibliography/466.pdf}, author = {D.M. Anderson and Nachman, P. and Richard E. Estell and Ruekgauer, T. and Kris Havstad and E.L. Fredrickson and L. W. Murray} } @proceedings {51334, title = {Physiological control of evapotranspiration by shrubs: scaling measurements from leaf to stand with the aid of comprehensive models}, volume = {Gen. Tech. Rep. INT-GTR-338}, year = {1996}, note = {//USDA//LTER-III//ProCite field[6]: InProCite field[8]: Compilers}, month = {May 23-25, 1995}, pages = {214-219}, publisher = {U.S. Department of Agriculture, Forest Service, Intermountain Research Station}, address = {Las Cruces, NM}, abstract = {

Plants exert major control over hydrologic budget- and, thus, over their own community stability- by their own transpiration and by their partial control over soil evaporation via soil shading. Furthermore, they exert major control over atmospheric humidity and consequent radiation balance in climate. Predicting further plant status and future climate will require predicting evapotranspiration (ET) over large regions and under varied climates. Models that are useful for diverse sites and species will require understanding of ET control at the process level, physiologically and micrometeorologically. ET prediction also presents significant challenges in quantifying vegetation and its spatial and physiological heterogeneity. We review how process-level understanding can be gained and tested by scaling down from satellite data and scaling up from leaf gas exchange. We have synthesized a model of leaf conductance and fitted its parameters to data on Larrea tridentata and Prosopis glandulosa. To scale up to whole-shrub and whole-stand evapotranspiration, we must sum over all leaves, accounting for (1) their different current microclimates and (2) their physiological states of acclimation to long-term histories of temperature and irradiance. We have developed models for each of these phenomena and are fitting them to data on many individual leaves. Our model can be integrated to predict whole-plant and whole-stand ET. We outline tests that will be performed on a 1000 m x 300 m transect of mixed shrubland on the Jornada Experimental Range.

}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, evapotranspiration, shrubs, model, shrub evapotranspiration, plant physiology, evapotranspiration, plant, evapotranspiration, proceeding, proceedings, shrub, evapotranspiration}, url = {files/bibliography/JRN00214.pdf}, author = {V. P. Gutschick}, editor = {J.R. Barrow and McArthur, E.D. and R. E. Sosebee and R. J. Tausch} } @article {51341, title = {Post-drought vegetation dynamics on arid rangelands in southern New Mexico}, year = {1996}, month = {1996}, pages = {102 pp}, institution = {College of Agriculture and Home Economics, New Mexico State University}, address = {Las Cruces, NM}, abstract = {

The arid and semiarid Southwest has frequent droughty periods that have a marked effect on the vegetation. Precipitation is extremely variable, both temporally and spatially (Martin and Cable 1974, Paulsen and Ares 1962). Perennial grasses provide the most reliable forage on grass-shrub ranges (Martin 1975). Cover for most species varied greatly from year to year in southern Arizona (Martin and Cable 1974). During the 1916{\textendash}18 drought, black grama{\textquoteright}s basal cover on the Jornada Experimental Range (JER) in southern New Mexico declined to 42\% of predrought cover (Nelson 1934). Black grama was the major plant species on lighter-textured soils. It practically recovered its stand during two years of favorable precipitation (1919{\textendash}20), then dropped very suddenly in the following two years of drought to the extremely low point of 11\% of the original cover. Black grama cover remained at a low level for the remainder of the 1921{\textendash}25 drought, then increased to its original size when summer rainfall was above average from 1926 to 1929. The accumulated deficits from 1915{\textendash}1988 headquarters from the 1921{\textendash}25 drought were 185 mm.2 From 1926 to 1929, July-September rainfall was 115 mm above average. Nelson (1934) found that black grama cover is mainly influenced by plant vigor at the start of the current growing season, as determined by rainfall from the previous summer. Changes in black grama basal area were closely correlated with precipitation during a 15-month period from July 1 of one year through September 30 of the next year.

}, url = {/files/bibliography/489.pdf}, author = {C.H. Herbel and Gibbens, Robert P.} } @inbook {51361, title = {Plio-Pleistocene pumice floods in the ancestral Rio Grande, southern Rio Grande rift, USA}, booktitle = {Sedimentary Geology}, volume = {103}, year = {1996}, note = {//LOCAL,USDA//LTER-III//ProCite field[6]: In}, month = {1996}, pages = {1-8}, publisher = {Elsevier Science B.V.}, organization = {Elsevier Science B.V.}, address = {Amsterdam, the Netherlands}, abstract = {

At least four times during the late Pliocene and early Pleistocene pyroclastic eruptions in the Jemez volcanic field, northern Rio Grande rift, flooded the ancestral Rio Grande with gravel-size pumice. Following as much as 400 km of fluvial transport, the pumice was deposited in beds 0.2 to 2.0 m thick in the Camp Rice Formation of the southern Rio Grande rift. A combination of reversal magnetostratigraphy and single-crystal sanidine 40Ar/39Ar dating constrains the ages of pumice-clast conglomerates at 3.1, ~ 2.0, 1.6, and 1.6 Ma. The coarsest pumice beds (cobbles, boulders) were deposited as antidune-like bedforms in a fluvial channel and as a crevasse-play sheet. Granule and pebble-sized pumice was deposited as dune bedforms in a fluvial channels and as ripple bedforms on the floodplain. The abundance of pumice clasts in the gravel fraction (60-100\%) suggest very rapid transport downriver, probably in a few days or weeks. The two older pumice-clast conglomerates correlate with the Puye Formation in the Jemez volcanic field, whereas the younger two are coeval to the Lower Bandelier Tuff and Cerro Toledo Rhyolite.

}, keywords = {book, books, chapter, chapters, geomorphology, processes, geomorphology, pumice flood, pumice flood, report, reports, volcano, pumice flood}, doi = {10.1016/0037-0738(96)00009-7}, url = {files/bibliography/JRN00215.pdf}, author = {Greg H. Mack and McIntosh, William C. and Leeder, Michael R. and Curtis H. Monger}, editor = {Crook, K.A.W. and Miall, A.D. and Sellwood, B.W.} } @article {51388, title = {Potential toxicity and feed value of onions for sheep}, journal = {Livestock Production Science}, volume = {42}, year = {1995}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1995. (http://www.sciencedirect.com/science/journal/03016226)}, month = {1995}, pages = {45-54}, abstract = {

The feeding, ruminal effects and potential toxicity of cull onions bulbs (Allium cepa) was compared to whole sorghum grain for growing wethers. In Expt. 1, 56 Polypay X Rambouillet wethers (avg. initial BW of 32.7 {\textpm} 0.88 kg) were assigned randomly to one of four dietary treatments (dry matter basis): (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\% was pelleted alfalfa (19\% CP). All wethers were group fed (seven wethers per pen; two replicates per treatment) for 6 weeks. Weight gain during the trial did not differ (P\> 0.05) among treatments. Packed cell volume tended to be less (P = 0.057) for the 33\% and 50\% onion groups during weeks 1 and 2, and was less (P\< 0.0001) for the same groups during week 3 (34, 33, 29 and 29\% for CON, 17, 33 and 50\%, respectively). Serum lactate dehydrogenase was increased (P\< 0.05) at weeks 3 and 6 in sheep on the 33\% and 50\% onion treatments. During Expt. 2, 15 ruminally cannulated wethers were individually fed diets similar to those Expt. 1, except onions were fed to replace sorghum grain to provide 0, 25 and 50\% of the dietary DM as onions. Ruminal fluid (P\> 0.05) and particulate passage (P\> 0.05) were not altered by feeding onions. Water intake by drinking decreased (P\< 0.0001) as percentage of onions in the diet increased, whereas total water intake (drinking and fed) increased (P\< 0.0001). Effects of onions on volatile fatty acid concentrations and ruminal pH were minimal (P\< 0.05), whereas ruminal ammonia-N concentration was greater (P\< 0.05) in wethers fed onions. We conclude that under conditions similar to those in our study, onions can be fed safely to sheep with weight gains comparable to those from whole sorghum grain.

}, keywords = {Allium cepa, digestion, sheep}, doi = {10.1016/0301-6226(94)00066-G}, url = {/files/bibliography/442.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @proceedings {51390, title = {Post-partum anestrus and fall pregnancy in 2-year-old range cows supplemented with protein and fat}, volume = {45}, year = {1995}, month = {1995}, pages = {76-79}, abstract = {

The objectives of this study were to determine the effect of supplements containing 50\% bypass protein with and without 10\% fat on rebreeding performance of two year old range cows. Sixty-three black Angus x Hereford cows with nursing calves at the USDA Jornada Experimental Range were divided by calving date and sex of calf into one of three pastures. Cows received either a 20\% crude protein supplement (20\%S), 48 \% crude protein supplement (which was 50\% bypass protein) (48\%S) or 48\%S with 10\% added fat (in the form of Alifet) (48\%S+F) from calving until breeding (February to May). Cattle were weighed before calving, before exposure to bulls and again at weaning. Serum samples were collected twice before (10 d intervals) breeding to determine percentage of cows that had cycled prior initiating the breeding season.

}, keywords = {beef cows, reproduction}, url = {/files/bibliography/443.pdf}, author = {Gambill, D.M. and M.K. Petersen and Hawkins, D.E. and Luna, I.T. and Corona, J.S.S. and Dunlap, D. and Kris Havstad} } @article {51393, title = {Pedogenic carbonate in soils of the Isaacks{\textquoteright} ranch surface, southern New Mexico}, journal = {Soil Science Society of America Journal}, volume = {59}, number = {2}, year = {1995}, note = {//LOCAL//NONE//}, month = {1995}, pages = {501-508}, abstract = {Pedogenic carbonate has potential as a chronological tool for vast areas of arid and semiarid regions. However, much more work is needed on variations in carbonate accumulation in soils of the same age. A long gully and study trench in southern New Mexico provide continuous exposures of soils of a drainageway and ridge of Isaacks{\textquoteright} Ranch age (8000-15 000 yr). A fine-loamy Typic Haplargid in the drainageway has a Stage II carbonate horizon and 108 kg/m2 of carbonate. Two coarse-loamy Typic Haplargids of the ridge side have Stage II carbonate horizons and 78 and 97 kg/m2 of carbonate, distinctly less than for the soil of the drainageway. The difference is attributed to finer texture (which would slow the wetting fronts) in the drainageway, and more water there for movement of carbonate into the soil. At the ridge crest, a facies change from coarse-loamy to sandy materials caused a change from Stage II nodules to Stage I coatings on grains. In the sandy material, a Typic Torripsamment has 22 kg/m2 of carbonate. In the coarse-loamy materials, a Typic Torriorthent has 60 kg/m2 of carbonate; the coarse-loamy materials must have captured carbonate that moved to greater depths in the Torripsamment. Although the totals obtained must be considered estimates, they indicate that the amount of pedogenic carbonate in Isaacks{\textquoteright} Ranch soils may range up to fivefold, that landscape position is an important factor in this range, and that texture of the parent materials can have a major effect on the amount of carbonate in soils of a given age regardless of landscape position.}, keywords = {article, articles, journal, journals, soil, pedogenic carbonates}, author = {L. H. Gile} } @inbook {51413, title = {Pedology in arid lands archaeological research: An example from southern New Mexico--Western Texas}, booktitle = {Pedological perspectives in archaeological research}, volume = {Special Publication 44}, year = {1995}, note = {//LOCAL//LTER III//ProCite field[6]: In}, month = {1995}, pages = {35-50}, publisher = {Soil Science Society of America}, organization = {Soil Science Society of America}, address = {Madison, WI}, abstract = {

Pedology is a key component of arid lands archaeological research, providing information about landscape evolution, the stratigraphic context of artifacts, and environmental change. As an example, a pedologic study was conducted for archaeologists at the Fort Bliss Military Installation, which covers slightly \>445 000 hectares of the northern Chihuahuan desert in southern New Mexico and western Texas. Part one of the study consisted of (i) mapping geomorphic surfaces and (ii) mapping deflated areas. Maps of geomorphic surfaces reveal the age and evolution of the arid landscape, and where archaeological sites might be buried. Deflation maps reveal areas where soils are deflated, stable, or recently buried. Artifact visibility is highest in deflated areas, but the stratigraphic integrity is generally lost. Areas buried by eolian sands, on the other hand, are most likely to contain artifacts with stratigraphic integrity, but artifact visibility is low. Part two of the study focused on paleoenvironmental changes. The most useful paleoenvironmental information was obtained from erosion-sedimentation history, fossil pollen preserved in buried soils, and 13C and 18O signatures in soil carbonates. Erosion, pollen, isotopes all revealed a major period of desertification beginning at the middle Holocene about the time Paleoindians gave way to people of the Archaic period.

}, keywords = {archeology, dunes \& artifacts, book, books, chapter, chapters, pedology, report, reports, soil, geomorphology}, doi = {10.2136/sssaspecpub44.c3 }, url = {files/bibliography/JRN00193.pdf}, author = {Curtis H. Monger}, editor = {Collins, M. E.} } @article {51430, title = {Persistence of desertified ecosystems: explanations and implications}, journal = {Environmental Monitoring Assessment}, volume = {37}, year = {1995}, month = {1995}, pages = {319-332}, abstract = {

Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were conducted to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are resistant and resilient to disturbance. Between 16 and 25\% of the intercepted rainfall is channelized to deep soil storage by stemflow and root channelization. Stemflow water is nutrient enriched and contributes to the {\textquotedblleft}islands of fertility{\textquotedblright} that develop under desert shrubs. Drought and rainfall augmentation experiments during the growing season after 5 consecutive years of summer drought found that (1) growth of creosotebushes, Larrea tridentata, was not significantly affected, (2) perennial grasses and forbs disappeared on droughted plots, (3) nitrogen mineralization increased in the short term, and (4) densities and biomass of spring annual plants increased on the droughted plots. Doubling summer rainfall for 5 consecutive years had less-significant effects. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes when remeasured in 1993. These data indicate that the shrub-dominated ecosystems persist because they are resistant and resilient to climatic and anthropogenic stresses.

}, keywords = {desertified, ecosystems, explanations, implications}, doi = {DOI: 10.1007/BF00546898}, url = {/files/bibliography/464.pdf}, author = {Walter G. Whitford and G. Martinez-Turanzas and E. Martinez-Meza} } @proceedings {51432, title = {Persistence of desertified ecosystems: Explanations and implications}, volume = {Reprinted from Environmental Monitoring and Assessment, Volume 37, Nos. 1-3, 1995}, year = {1995}, note = { //NMSU, USDA//LTER III//ProCite field[6]: In}, month = {October 24-29, 1}, pages = {319-332}, publisher = {Kluwer Academic Publishers}, address = {Tucson, Arizona}, abstract = { Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were done to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are resistant and resilient to disturbance. Between 16 and 25\% of the intercepted rainfall is channelized to deep soil storage by stemflow and root channelization. Stemflow water is nutrient enriched and contributes to the \"islands of fertility\" that develop under desert shrubs. Drought and rainfall augmentation experiments during the growing season after 5 consectuvie years of summer drought found that (1) growth of creosotebushes, Larrea tridentata, was not significantly affected, (2) perennial grasses and forbs disappeared on droughted plots, (3) nitrogen mineralization increased in the short term, and (4) densities and biomass of spring annual plants increased on the droughted plots. Doubling summer rainfal for 5 consecutive years had less-significant effects. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes when remeasured in 1993. These data indicate that the shrub-dominated ecosystems persist because they are resistant and resilient to climatic and anthropogenic stresses.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, desertification, shrubs, desertification,Prosopis dunelands, herbicide impact, Prosopis duneland, proceeding, proceedings, rainfall simulation,Larrea, shrub, desertification, shrub, stemflow, stemflow, shrub}, isbn = {0-7923-3919-3}, author = {Walter G. Whitford and G. Martinez-Turanzas and E. Martinez-Meza}, editor = {D. A. Mouat and Charles F. Hutchinson} } @conference {51465, title = {Persistence of desertified ecosystems: explanations and implications}, booktitle = {International Symposium and Workshop on Desertification in Developed Countries: Why Can{\textquoteright}t We Control It?}, year = {1994}, month = {October 24-29, 1}, pages = {18-19}, address = {Tucson, AZ}, abstract = {

Desertification in much of the southwestern U.S. and northern Mexico has resulted in the replacement of perennial grasslands with desert scrublands. Scrublands dominated by C3 shrubs exhibit long-term persistence, resist control efforts, and are resilient in areas where control and revegetation with grasses have been attempted. Experiments using 5 consecutive years of summer drought using \"rain-out\" shelters and 5 consecutive years of approximately doubling the summer rainfall resulted in no significant changes in annual net above-ground primary production of creasotebush, barren tridentata, in either of the treatments. There were significant changes in species composition and above-grind net primary production of spring annual plants and some reduction of perennial grasses and fortis in droughted plots. There were small changes in decomposition rates and nitrogen mineralization potential but no quantitative differences in the Studies of shrub water budgets demonstrated that between 6 percent and 25 percent of the intercepted rainfall was translocated to deep soil storage by stemflow and root channelization. Nutrient minerals in stemflow water on creosotebush were 5 to 10 times more concentrated in stemflow than in thrnttghfsli and bulk precipitation. These data demonstrate that once shrubs are established, islands of resource enrichment of water and nutrients develop under the shrubs. The result is self-reinforcing systems that are resistant to disturbance. The characteristics of the shrub-dominated ecosystems documented in the experiments demonstrate that they are likely to persist with climate change. The data from these studies suggest that management of desertified landscapes in North America should focus on maintaining the residual grasslands and on the economic uses of the shrub-dominated ecosystems.

}, keywords = {desert scrublands, desertification, desertified landscapes, maintaining grasslands, management}, author = {Walter G. Whitford and G. Martinez-Turanzas and E. Martinez-Meza} } @article {51466, title = {Plant production and soil microorganisms in late-successional ecosystems: A continental-scale study}, journal = {Ecology}, volume = {75}, year = {1994}, note = {//??//LTER III//}, month = {1994}, pages = {2333-2347}, abstract = {

Annual C inputs from plant production in terrestrial ecosystems only meet the maintenance energy requirements of soil microorganisms, allowing for little or no net annual increase in their biomass. Because microbial growth within soil is limited by C availability, we reasoned that plant production should, in part, control the biomass of soil microorganisms. We also reasoned that soil texture should further modify the influence of plant production on soil C availability because fine{\textemdash}textured soils typically support more microbial biomass than coarse{\textemdash}textured soils. To test these ideas, we quantified the relationship between aboveground net primary production (ANPP) and soil microbial biomass in late{\textemdash}successional ecosystems distributed along a continent{\textemdash}wide gradient in North America. We also measured labile pools of C and N within the soil because they represent potential substrate for microbial activity. Ecosystems ranged from a Douglas{\textemdash}fir forest in the western United States to the grasslands of the mid{\textemdash}continent to the hardwood forest in the eastern U.S. Estimates of ANPP obtained from the literature ranged from 82 to 1460 g{\textdegree}m{\textemdash}2{\textdegree}yr{\textemdash}1. Microbial biomass C and N were estimated by the fumigation{\textemdash}incubation technique. Labile soil pools of C and N and first{\textemdash}order rate constants for microbial respiration and net N mineralization were estimated using a long{\textemdash}term (32 wk) laboratory incubation. Regression analyses were used to relate ANPP and soil texture with microbial biomass and labile soil C and N pools. Microbial biomass carbon ranged from 2 g/m2 in the desert grassland to 134 g/m2 in the tallgrass prairie; microbial N displayed a similar trend among ecosystems. Labile C pools, derived from a first{\textemdash}order rate equation, ranged from 115 g/m2 in the desert grassland to 491 g/m2 in the southern hardwood forest. First{\textemdash}order rate constants for microbial respiration (k) fell within a narrow range of values (0.180 to 0.357 wk{\textemdash}1), suggesting that labile C pools were chemically similar among this diverse set of ecosystems. Potential net N mineralization rates over the 32{\textemdash}wk incubation were linear in most ecosystems with first{\textemdash}order responses only in the alpine tundra, tallgrass prairie, and forests. Microbial biomass C displayed a positive, linear relationship with ANPP (r2 = 0.51), but was not significantly related to soil texture. Labile C also was linearly related to ANPP (r2 = 0.32) and to soil texture (r2 = 0.33). Results indicate that microbial biomass and labile organic matter pools change predictably across broad gradients of ANPP, supporting the idea that microbial growth in soil is constrained by C availability.

}, keywords = {article, articles, ecosystem, plant production, ecosystem, soil microorganisms, journal, journals, plant productivity, soil processes, soil microorganism, plant productivity, succession, plant production, succession, soil miroorganisms}, doi = {10.2307/1940888}, url = {files/bibliography/JRN00177.pdf}, author = {Zak, D. R. and D. Tilman and R. R. Parmenter and Rice, C. W. and F. M. Fisher and Vose, J. and Milchunas, D. and Martin, C. W.} } @article {51490, title = {Pollination ecology of Yucca elata: an experimental study of a mutualistic association}, journal = {Oecologia}, volume = {93}, year = {1993}, note = {//LOCAL//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1993}, pages = {512-517}, abstract = {

The pollination biology of a population of 250 Yucca elata and the prodoxid yucca moth Tegeticula yuccasella have a mutualistic association that is essential for the successful sexual reproduction of both species. However, a wide range of other invertebrate species visit flowers during the day and at night. Our aim was to quantify the role of yucca moths and other invertebrate visitors in pollination and fruit set, using manipulative field experiments. Inflorescences were bagged during the day or night (N= 12 Inflorescences) to restrict flower visitors to either nocturnal or diuranl groups. Yucca moths were active exclusively nocturnally during the flowering period and thus did not visit Inflorescences that were unbagged during the day. None of the 4022 flowers exposed only to diurnal visitors set fruit, whereas 4.6\% of the 4974 flowers exposed only to nocturnal visitors (including yucca moths) produced mature fruit. The proportion of flowers production fruit in the latter treatment was not significantly different from unbagged control Inflorescences. In a series of experimental manipulations we also determined that: (1) flowers opened at dusk and were open for tow days on average, but were only receptive to pollen on the first night of opening; (2) pollen must be pushed down the stigmatic tube to affect pollination; and (3) most plants require out-cross pollination to produce fruit. The combination of these results strongly suggests that yucca moths are the only species affecting pollination in Y. elata and that if another species was to affect pollination, it would be a rare event.

}, keywords = {article, articles, invertebrate, Tegeticula, invertebrate, yucca moth, journal, journals, mutualism, plant, Yucca, pollination ecology, Tegeticula, Yucca, yucca moth, Tegeticula, Yucca, pollination ecology}, doi = {10.1007/BF00328959}, url = {files/bibliography/93-Oecologia-Whitford.pdf}, author = {Craig D. James and Hoffman, M. Timm and David C. Lightfoot and Gregory S. Forbes and Walter G. Whitford} } @article {51502, title = {Preliminary data on the spider and solpugid fauna of the Jornada}, year = {1993}, note = {//NMSU, USDA//NONE//Manuscript//ProCite field[2]: Dept. of Entomology, NMSU}, month = {1993}, type = {unpublished hard copy}, abstract = {Las Cruces, New MexicoNew Mexico State University}, keywords = {list, spiders, list,solpugid fauna, solpugid fauna,list, spider,list}, author = {D. Richman} } @conference {51527, title = {Perceptions from review of 80 years of range research in the Chihuahuan Desert}, booktitle = {Annual Meeting, Society for Range Management}, year = {1992}, month = {1992}, pages = {No. 086}, abstract = {Rangeland research has been conducted in the northern Chihuahuan Desert of southern New Mexico for the past 80 years. Early scientists with the well recognized names of Jardine, Forsling, and Chapline, were followed by Campbell, Canfield, and Parker and, more recently, by Paulsen and Herbel. Their research efforts were impressive and productivity was substantial. Four observations from a review of their published record are: (1) Basic tenets of management were established in the early 1920s while later research simply refined and/or slightly expanded these tenets. (2) Range improvement has been a constant thrust, but many tools resulting from this research are not currently applicable. (3) Current management concerns remain poorly assessed, especially as related to applicable data on grazing capacity and vegetation dynamics. (4) And, recent research efforts are more diverse, basic, descriptive and less directly applicable to management needs. It could be concluded that range science has failed to illuminate principles applicable to today{\textquoteright}s management issues in the Southwest. This general viewpoint and the viewpoint that range science and range management are separate but complementary endeavors have been recently expressed (Provenza, F.D., 1991, JRM 44:281-183). However, review of literature (especially from biological sciences) presents numerous basic principles with application to rangelands. The present deficit is lack of application of these principles by range researchers to the development of tools and new uses of current tools suitable for management goals given the reality of present day constraints. A recent survey of future range research topics indicates ecology and improvements as top priorities with a scattering of other interests (Hardesty, L.H., 1991, JRM 44:289-294). To effectively use the next 80 years of research we must continually identify current management needs, utilize applicable principles identified from all scientific fields, and emphasize development of usable tools.}, keywords = {application of principles, Chihuahuan Desert, management issues, perceptions, range research}, author = {Kris Havstad} } @proceedings {51528, title = {Production alternatives}, year = {1992}, month = {1992}, pages = {255-256}, author = {C.H. Herbel} } @article {51578, title = {Productivity of creosotebush foliage and associated canopy arthropods along a desert roadside}, journal = {American Midland Naturalist}, volume = {125}, year = {1991}, month = {1991}, pages = {310-322}, abstract = {

A sampling study was designed to test the hypothesis that creosotebush (Larrea tridentata) shrubs along a roadside were larger, more vigorous and supported greater populations of foliage arthropods than shrubs growing 20 m away from the road margin. Structural and chemical attributes of shrubs and associated foliage arthropods were measured. Roadside shrubs were larger, had denser foliage, more flowers, higher foliar nitrogen contents and lower foliar resin contents than shrubs growing away from the road. Foliage arthropod densities were significantly higher on roadside shrubs. Sap-feeding herbivores dominated numerically and accounted for most of the differences in arthropod abundances between roadside and nonroadside shrubs. Numbers of foliage arthropods were positively correlated with shrub size, density and foliar nitrogen contents, and negatively correlated with foliar resin contents. These findings, in concordance with other studies, indicate that in arid environments productive, vigorous plants are preferred hosts for herbivorous insects.

}, keywords = {arthropods, creosotebush}, doi = {10.2307/2426235 }, url = {/files/bibliography/JRN00139.pdf}, author = {David C. Lightfoot and Walter G. Whitford} } @article {51584, title = {Pressure solution: possible mechanism for silicate grain dissolution in a petrocalcic horizon}, journal = {Soil Science Society of America Journal}, volume = {55}, number = {6}, year = {1991}, note = {//LOCAL//NONE//}, month = {1991}, pages = {1625-1629}, abstract = {In the petrocalcic horizon of a middle Pleistocene soil in southern New Mexico, up to 58\% of the silicate grains have dissolution features, such as embayed and serrated edges. The purpose of this study was to determine if pressure solution produced the dissolution features. Samples were analyzed in thin section using light and electron microscopy, and by measuring pH and Si concentration of saturated paste extracts. Four lines of evidence support the pressure-solution mechanism in the petrocalcic horizon: (i) silicate grains are smooth where they contact pores, but serrated where they contact calcite; (ii) dissolution pits on silicate grains generally match the shapes of impacted calcite crystals; (iii) silicate grains are concentrated into horizontal layers in the upper petrocalcic horizon, which testifies to the pressure generated by crystallizing calcite; and (iv) outside the petrocalcic horizon where crystallization pressure is less, silicate grains coated with calcite crystals have fewer dissolution features than grains in the petrocalcic horizon. No relationship was apparent between silicate-grain dissolution and petrocalcic-horizon pH or Si concentration. The pH (7.6) was below, and the Si concentration (8.6 mg L-1) was above the levels required for dissolution. Thus, pressure generated by crystallizing calcite appears to have caused dissolution features on the silicate grains in the petrocalcic horizon.}, keywords = {article, articles, calcite, geomorphology, petrocalcic horizon, journal, journals, soil, petrocalcic horizon, soil,silicate dissolution}, author = {Curtis H. Monger and LeRoy A. Daugherty} } @mastersthesis {51586, title = {Postweaning growth and cyclicity of barzona, beefmaster and brangus heifers grazing semidesert rangeland}, year = {1991}, note = {//??//NONE//}, month = {1991}, pages = {46}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle grazing, productivity, dissertation, dissertations, theses, thesis}, author = {Morupisi, Carter Nkatla} } @article {51591, title = {Processes controlling ammonia volatilization from Chihuahuan Desert soils}, journal = {Soil Biology and Biochemistry}, volume = {23}, number = {7}, year = {1991}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1991}, pages = {637-642}, abstract = {

Ammonia volatilization was measured at three sites in the Chihuahuan Desert of southern New Mexico, U.S.A. In dry soils, ammonia volatilization ranged from 9 to 11 ug N m-2 day -1 in a shrubland site after an experimental addition of water. Ammonia volatilization also increased with experimental additions of NH4Cl and decreased with additions of sucrose. Competition by nitrifiers for available NH4+ had little effect on NH3 volatilization; N-Serve, added to inhibit nitrification, decreased NH3 volatilization in a grassland site and had little effect at other sites. We suggest that NH3 volatilization is controlled by the rate of mineralization of NH4+ from soil organic matter, and mineralization is stimulated by rainfall. Overall rates of NH3 volatilization from undisturbed desert ecosystems appear to be much lower than those reported for rangeland and agricultural soils.

}, keywords = {ammonia volatilization, article, articles, biogeochemistry, ammonia volatilization, biogeochemistry, ammonium mineralization, journal, journals, nutrient cycling, shrubland,ammonia, soil, ammonia volatilization, soil,ammonium mineralization}, doi = {10.1016/0038-0717(91)90076-V}, url = {files/bibliography/JRN00138.pdf}, author = {W. H. Schlesinger and Peterjohn, William T.} } @mastersthesis {51607, title = {The physiological ecology of Gutierrezia sarothrae (Pursh) Rusby in the Chihuahuan desert of southern New Mexico}, year = {1990}, note = {//??//NONE//}, month = {1990}, pages = {115}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, Gutierrezia,physiology, physiology,Gutierrezia, theses, thesis}, author = {Briede, Jan-Willem} } @article {51619, title = {Phytophagous insects enhance nitrogen flux in a desert creosotebush community}, journal = {Oecologia}, volume = {82}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {18-25}, abstract = {

We tested the hypothesis that herbivorous insects on desert shrubs contribute to short-term nitrogen cycling, and increase rates of nitrogen flux from nutrient rich plants. Creosotebush (Larrea tridentata) shrubs were treated with different combinations of fertilizer and water augmentations, resulting in different levels of foliage production and foliar nitrogen contents. Foliage arthropod populations, and nitrogen in canopy dry throughfall, wet throughfall and stemflow were measured to assess nitrogen flux rates relative to arthropod abundances on manipulated and unmanipulated shrubs over a one-month period during peak productivity. Numbers and biomass of foliage arthropods were significantly higher on fertilized shrubs. Sap-sucking phytophagous insects accounted for the greatest numbers of foliage arthropods, but leaf-chewing phytophagous insects represented the greatest biomass of foliage arthropods. Measured amounts of bulk frass (from leaf-chewing insects) were not significantly different among the various treatments. Amounts of nitrogen from dry and wet throughfall and stemflow were significantly greater under fertilized shrubs due to fine frass input from sap-sucking insects. Increased numbers and biomass of phytophagous insects on fertilized shrubs increased canopy to soil nitrogen flux due to increased levels of herbivory and excrement. Nitrogen excreted by foliage arthropods accounted for about 20\% of the total one month canopy to soil nitrogen flux, while leaf litter accounted fro about 80\%.

}, keywords = {arthropod, also SEE , article, articles, creosotebush, insect, phytophagous, journal, journals, nitrogen amendment, nitrogen cycling, Larrea, nitrogen flux, phytophagous insects, rainfall simulation, water amendment}, doi = {10.1007/BF00318528}, url = {files/bibliography/JRN00126.pdf}, author = {David C. Lightfoot and Walter G. Whitford} } @article {51621, title = {Population dynamics of a playa community in the Chihuahuan Desert}, journal = {The Southwestern Naturalist}, volume = {35}, number = {4}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//updated 04/14/2008; PDF available}, month = {1990}, pages = {393-402}, abstract = {

Population responses of desert playa organisms were examined following two separate rain storms (spring and late summer-fall) that flooded a playa and stock tank located in southern New Mexico. Invertebrate species that appeared following both floods included the crustaceans Streptocephalus texanus, thamnocephalus platyurus, Eulimnadia texana, Triops longicaudatus, Moina wierzejskii and the rotifers Brachionus sp., Polyarthra sp., and Pedalia sp. Moina wierzejskii produced three generations during the single spring flood while other species produced a single generation. Initial population levels for all species were very high. Fairy shrimp levels decreased quickly, and population levels of Moina wierzejskii were depressed until levels of all other species were low. Arthropod species did not produce large numbers of drought-resistant eggs in response to the lowering of the water level. Tadpoles of two species of anurans, the spadefoot toad (Scaphiopus multiplacatus) and the true toad (Bufo cognatus) occurred in the playa following spring flooding. Tadpoles of Bufo cognatus were not collected after the late summer rain. Tadpoles, particularly spadefoot toads, preyed on other tadpoles and fairy shrimp (Anostraca). Apparently, both biotic and abiotic factors were important in the population dynamics of playa organisms. Biotic interactions appeared more important during the second flood when the population densities of most species were higher.

}, keywords = {article, articles, flooding,playa, invertebrate,playa, journal, journals, playa, flooding, playa,anurans, playa,arthropods, playa,invertebrates, playa,population dynamics, population dynamics,playa}, doi = {10.2307/3672036 }, url = {files/bibliography/90-SWNat-Whitford.pdf}, author = {William P. MacKay and S. J. Loring and T. M. Frost and Walter G. Whitford} } @article {51658, title = {Plant-feeding nematodes in deep-rooting desert ecosystems}, journal = {Ecology}, volume = {70}, number = {6}, year = {1989}, note = {//NMSU,USDA//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {1665-1678}, abstract = {

In the Chihuahuan Desert of southern New Mexico, mesquite (Prosopis glandulosa) occurs in a variety of landscape positions where water may accumulate to varying depths. The structure of Chihuahuan Desert landscapes has changed dramatically in the past 100 yr with mesquite expanding from its original distribution (playa, arroyo) into grassland and dune ecosystems. Our objective was to examine spatial and seasonal distribution of plant-feeding nematodes and the potential importance of herbivory in four mesquite communities (playa, arroyo, dunes, grassland) hypothesized to differ in rooting depth and distribution. These sites were compared to a more shallow-rooted creosote bush (Larrea tridentata) community. Intact soil cores were recovered to depths of 13 m beneath the canopies of mesquite or creosote bush using a continuous sampling tube drilling system in the winter, spring, and fall in Jornada LTER site, Las Cruces, New Mexico.

}, keywords = {article, articles, creosotebush, nemotode, deep soil, herbivory, journal, journals, mesquite, nematode, nematode, arroyo, nematode, creosotebush, nematode, dune, nematode, grassland, nematode, plant-feeding, nematode, playa, roots, nematodes, soil fauna, deep-rooted plants, soil,nematodes}, doi = {10.2307/1938101}, url = {files/bibliography/JRN00103.pdf}, author = {D. W. Freckman and R. A. Virginia} } @conference {51659, title = {Phenology of native and introduced grasses in southern New Mexico}, booktitle = {42nd Annual Meeting, Society for Range Management}, year = {1989}, month = {1989}, pages = {61}, author = {Gibbens, Robert P.} } @article {51679, title = {Patterns of stratified soil water loss in a Chihuahuan Desert community}, journal = {Soil Science}, volume = {148}, number = {4}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {244-249}, abstract = {An accurate assessment of the moisture content of surface soils in arid and semiarid systems is necessary to predict the productivities of shallow-rooted plants and decomposition rates of surface and near-surface litter. Soil water loss has often been assumed to proceed in a stepwise manner, beginning at the surface and proceeding to deeper layers as the profile dries. However, recent studies suggest that plants draw water simultaneously from many or all soil layers where roots are present. We examined the potential significance of this phenomenon in a semiarid ecosystem utilizing two simulation models, one integrating soil water loss throughout the profile and the other sequentially removing water from soil horizons. Field observations indicate greater moisture retention in shallow soils than could be explained by a stepwise removal of water; a better correlation was achieved by simultaneously drawing water from all horizons.}, keywords = {arid ecosystem, article, articles, evapotranspiration, journal, journals, model, soil water loss, model, SWATS, plants,shallow-rooted, soil water content, soil water loss, soil water potential}, author = {Daryl L. Moorhead and J. F. Reynolds and P. J. Fonteyn} } @proceedings {51708, title = {The potential use of animals for the dispersal and establishment of native forage plants}, year = {1988}, month = {1988}, pages = {121}, author = {J.R. Barrow} } @article {51742, title = {Pollen selection for heat tolerance in cotton}, journal = {Crop Science}, volume = {28}, number = {5}, year = {1988}, month = {1988}, pages = {857-859}, abstract = {

Pollen from cotton (Gossypium hirsutum L.) cultivars, which demonstrate heat tolerance in the field, generally express higher fertility after heat treatment than pollen from heat sensitive cultivars. The objective of this study was to determine, if pollen could be heat treated to eliminate all but those grains with genetic heat tolerance. Genes for heat tolerance could then be selected in the pollen and effectively transferred by the backcross method. A highly heat tolerant breeding line, 7456, of G. barbadense L. was used as the donor parent and {\textquoteright}Paymaster 404{\textquoteright}, a heat sensitive cultivar, as the recurrent parent and all crosses were made with pollen treated 15 h at 35 {\textdegree}C generate F1, F2, and first and second backcross populations. Increased heat tolerance, as measured by fertile pollen after heat treatment, was observed in plants from all populations. Similar heat tolerance patterns were observed in the parents, F1, F 2, and first backcross populations, when plants were grown to maturity at high temperatures in a growth chamber. Pollen selection through heat treatment allows screening for large numbers of genetic combinations in pollen and may be a valuable method of breeding for heat tolerance and possibly other stress tolerance characteristics.

}, doi = {10.2135/cropsci1988.0011183X002800050030x}, url = {/files/bibliography/336.pdf}, author = {Rodriguez-Garay, B. and J.R. Barrow} } @article {51781, title = {Phosphorous and pH tolerances in the germination of the desert shrub Larrea tridentata (Zygophyllaceae)}, journal = {Madro{\~n}o}, volume = {34}, number = {1}, year = {1987}, note = {//NMSU//NONE, LTER//}, month = {1987}, pages = {63-68}, abstract = {Seeds of Larrea tridentata, a dominant shrub of deserts in the southwestern U.S., were germinated on both a pH and phosphorus (P) gradient to determine if requirements for germination can help explain the field distribution of Larrea. Germination decreased significantly above pH 8, which is consistent with the conspicuous absence of Larrea from high pH sodic or saline desert soils. Although Larrea tends to be absent from noncalcareous soil, seed germination was not inhibited in acidic solutions. Germination showed no response to P or to interactions of pH and P. In contrast, recent literature has suggested that Larrea may be restricted to calcareous soils of low phosphorus availability due to toxicity of high concentrations of P to seedlings.}, keywords = {article, articles, germination, Larrea, journal, journals, Larrea, germination, phosphorous, Larrea, germination, soil pH, pH tolerances, Larrea, phosphorous, seed, germination}, author = {Kate Lajtha and Weishampel, John and W. H. Schlesinger} } @article {51783, title = {Primary productivity in arid lands: myths and realities}, journal = {Journal of Arid Environments}, volume = {13}, year = {1987}, note = {//NMSU//US-IBP//}, month = {1987}, pages = {1-7}, abstract = {We tend to view arid environments as harsh and water-limited, due to low amounts of precipitation. In fact, many sites within desert regions receive considerable amounts of water due to run-on; for example, washes (arroyos, wadis). The productivity of these can be high. However, in reality, their extent is small. We often assume productivity of deserts to be only water-limited. Recent research in arid ecosystems indicates, however, that nutrients can be critical to production. We also think of desert precipitation as being unpredictable, in addition to low in quantity. Nevertheless, many of the major arid lands of the world are characterized by highly seasonal patterns of precipitation. Native plant and animal populations have evolved numerous tactics which capitalized on the predictable timing of precipitation. Humans have learned to exploit this predictability by growing crops and raising livestock that can gain from seasonal patters. Humans also manipulate arid environments by removing the limits of productivity through irrigation and fertilization and, while some cases of agricultural production are noteworthy, the reality is that the cost/benefit ratio is not favorable. Furthermore, extensive arid and semi-arid areas are undergoing rapid desertification. Monitoring desertification is essential to our future understanding of arid and semi-arid land productivity.}, keywords = {article, articles, journal, journals, plant, primary production, precipitation, primary production, primary production, nitrogen amendment, primary production, rainfall patterns, rainfall, SEE }, author = {J. Ludwig} } @conference {51797, title = {Photosynthesis and water relations of mesquite and fourwing saltbush cohabiting sand dunes in the northern Chihuahuan Desert}, booktitle = {40th Annual Meeting, Society for Range Management}, year = {1987}, month = {1987}, pages = {150}, author = {Sisson, W.B. and Gibbens, Robert P.} } @article {51815, title = {Preliminary analyses and comparisons of sediment yield data from the New Mexico LTER site (Jornada site)}, year = {1986}, note = {//NMSU//LTER I//ProCite field[6]: In}, month = {1986}, pages = {25-34}, institution = {Illinois Department of Energy and Natural Resources}, address = {Champaign, Illinois}, abstract = {

This is a report on the preliminary analyses of water and sediment yield data collected at the Jornada LTER site north of Las Cruces, New Mexico. The report is intended to serve two purposes: to supply LTER personnel a general overview of the data collected to date in order to facilitate future experimental plans, and to provide a summary of the data for those involved in water and sediment studies at other LTER sites. The analyses are limited in scope to those data provided by LTER experiments, both ongoing and as completed by two graduate students. Numerous statistical tests and comparisons were conducted on the data sets in order to determine similarities, differences, and functional relationships where they existed. We used the Statistical Analysis System (SAS) on the New Mexico State University (NMSU) IBM 3081D mainframe computer to summarize and analyze the data. The three data sets we used were collected by Elkins (1983) for his Ph.D degree, by Bach (1984) for her M.S. degree, and by LTER personnel in an ongoing study (W.G. Whitford, Department of Biology, New Mexico State University, unpublished data). We analyzed 385 plot events (number of times measurements were taken from a plot), with 272 of these supplied by LTER personnel. A detailed analysis is provided in the analysis section of this report.

}, keywords = {book, books, chapter, chapters, grassland, playa, hydrology, natural runoff, hydrology, rainfall simulation, hydrology, runoff, hydrology, shrubland, hydrology, termites, hydrology,grassland, rainfall simulation, rainfall, runoff, report, reports, sediment yield, termite,hydrology}, isbn = {State Water Survey Contract Report 387}, author = {Bolin, Susan B. and Timothy J. Ward}, editor = {J. Rodger Adams} } @book {51826, title = {Physiographic provinces I and II}, series = {New Mexico in Maps}, year = {1986}, note = {//LOCAL//NONE//ProCite field[6]: In}, month = {1986}, pages = {23-31}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, edition = {Second Edition}, address = {Albuquerque, New Mexico}, abstract = {A physiographic province is a region with a particular pattern of landforms that differs significantly from that of adjacent regions. Each province has a distinctive geologic framework and particular combinations of topographic and hydrographic features that have evolved through geologic time. The individual landforms (e.g., mountains, canyons, alluvial fans) that in aggregate make up the varied natural landscapes of a given province reflect a variety of geomorphic processes. In New Mexico these range from the action of deep-seated (hypogene) forces, including volcanism and tectonism, such as erosion and sedimentation by water or wind.}, keywords = {book, books, chapter, chapters, geomorphic processes, map,physiographic provinces, physiographic provinces, map, report, reports}, author = {J. Hawley}, editor = {Jerry L. Williams (ed.)} } @proceedings {51834, title = {Polypay sheep and their usefulness in farm flock operations}, year = {1986}, month = {1986}, pages = {89-103}, abstract = {

The shepherding of sheep is essentially as old as the existence of man. Man{\textquoteright}s very survival, especially in harsh environments, at times has been very dependent on the attributes of sheep. His wealth has been equated to the number of sheep he owned, and his comfort and well-being were greatly enhanced by his flock of sheep.

}, url = {/files/bibliography/299.pdf}, author = {Clarence V. Hulet} } @article {51837, title = {Plant response to variations in nitrogen availability in a desert shrubland community}, journal = {Biogeochemistry}, volume = {2}, year = {1986}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1986}, pages = {29-37}, abstract = {

Spatial variations in nitrogen availability were studied in a desert community codominated by Larrea tridentata (DC.) Cov. and Prosopis glandulosa Torr. Measurements of natural 15N values in tissues suggested that Prosopis obtains approximately half of its nitrogen through direct symbiotic fixation. Soils were collected under 1) Prosopis shrubs, 2) Larrea shrubs \< 2 m from Prosopis (LP), and 3) Larrea\< 2 m from other Larrea but \> 5 m from the nearest Prosopis (LL). Prosopis soils showed significantly higher rates of nitrogen mineralization than LL soils in both A and B horizons. Rates of mineralization in LP soils were significantly higher than rates in LL soils only in the B horizon and were not significantly different from rates in Prosopis soils. Leaf nitrogen concentrations were significantly higher in LP shrubs (2.06\%) than in LL shrubs (1.78\%), although 15N values did not differ between the two shrub types. Nitrogen concentrations in Perezia nana Gray, a perennial herb, were greater in plants under Prosopis shrubs (2.09\%) than under LP shrubs (1.93\%) or LL shrubs (1.67\%). Despite apparent differences in nitrogen availability, biomass of Larrea and density of Perezia did not differ significantly among these sites.

}, keywords = {article, articles, desert shrublands, journal, journals, Larrea,nitrogen, nitrogen availability, nitrogen mineralization, nitrogen stable isotopes, Prosopis,nitrogen}, doi = {10.1007/BF02186963 }, url = {files/bibliography/JRN00038.pdf}, author = {Kate Lajtha and W. H. Schlesinger} } @book {51841, title = {Primary production variability in desert ecosystems}, series = {Pattern and Process in Desert Ecosystems}, year = {1986}, note = {//NMSU//US-IBP//ProCite field[6]: In}, month = {1986}, pages = {5-17}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {

The primary objective of this paper is to report and discuss variations in AAGNPP of deserts. Specific objectives are related to a number of questions. What ecosystem types within and between deserts have the greatest variations in AAGNPP? Under what environmental conditions are highs and lows observed? Are factors other than water availability limiting ANPP in deserts? What is the probable contribution of belowground production to total annual net primary production (ANPP)? Before discussing these question, I will first attempt to precisely define what I mean by primary production. Then I will present a brief history of primary production studies in deserts, pointing out the recentness of such studies. I will also discuss the methodological difficulties in measuring ANPP in deserts, which largely explains the paucity of primary production studies in deserts.

}, keywords = {book, books, chapter, chapters, primary production, methods, primary production, variability, report, reports}, doi = {10.2307/1308782 }, url = {files/bibliography/86-UNM-Whitford.pdf}, author = {J. Ludwig}, editor = {Walter G. Whitford} } @proceedings {51857, title = {Pleistocene climates and endemism in the Chihuahuan Desert flora}, year = {1986}, note = { //LOCAL//NONE//ProCite field[6]: In}, month = {October 20-21, 1}, pages = {1-19}, publisher = {Allen Press}, address = {Chihuahuan Desert Research Institute, Sul Ross State University}, abstract = {

Chronological series of radiocarbon dated plant macrofossil assemblages from small geographic areas are providing excellent developmental sequences of vegetation for the last 35,000 years in the northern Chihuahuan Desert. Midden vegetation chronologies have been completed along a latitudinal gradient from the San Andres (33 degrees 11{\textquoteright} N) and Sacramento mountains, New Mexico, and the Jueco Mountains (32 degrees N), and the Rio Grande Village area (29 degrees 30{\textquoteright}N) and Maravillas Canyon ( 29 degrees 33{\textquoteright}N) in the Big Bend of Texas. Although the chronologies demonstrate some differences in composition and the timing of vegetation changes, they agree in a stepwise progression with the most mesic pinyon-juniper-oak vegetation in the Late Wisconsin and the most xeric in the last 4000 years. The Middle Holocene (about 8000-4500 years ago) was apparently very warm with strongly developed summer monsoons and a maximum expansion of grasslands. About 4500 year ago, a creosote-desertscrub corridor between the Chihuahuan and Sonoran deserts was established for the first time since the last interglacial. Deserts are probably at their maximum expansion today with the harshest climates of the present interglacial.

}, keywords = {abstract, abstracts, Chihuahuan Desert, endemic flora, Chihuahuan Desert, paleoclimate, climate,pleistocene, conference, conference proceedings, conferences, ecosystem, pleistocene climates, endemism, flora,succession, packrat middens, pleistocene climates, proceeding, proceedings, succession, Chihuahuan Desert flora, succession,flora}, url = {/files/bibliography/VanDevender_1986_Pleistocene-climates-and-endemism-in-desert-flora.pdf}, author = {T.R. Van Devender}, editor = {Barlow, Jon C. and Michael A. Powell and Timmermann, Barbara N. (eds.)} } @proceedings {51863, title = {Pattern in desert ecosystems: water availability and nutrient interactions}, volume = {Vol. 3A/B}, year = {1986}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//ProCite field[6]: In}, month = {1986}, pages = {109-117}, publisher = {Hebrew University Press}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, nutrient, interactions, proceeding, proceedings, water, availability}, author = {Walter G. Whitford} } @article {51875, title = {Predation versus resource limitation in survival of adult burrowing spiders (Araneae: Lycosidae)}, journal = {Oecologia}, volume = {67}, year = {1985}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1985}, pages = {71-75}, abstract = {

The influences of food supply and density on adult survival were examined in the burrowing wolf spider Geolycosa rafaelana (Lycosidae), using manipulations of spider populations on eight 400 sq m experimental plots. A total of 110 adult spiders were captured, weighed, marked, and returned to their burrows during April{\textendash}May 1983. Treatments of (1) food supplementation, (2) density reduction, (3) food supplementation combined with density reduction, and (4) no manipulation (control) were applied to the eight populations, and adult survival and reproduction were monitored during May{\textendash}October 1983. Survival rates were higher for nonreproducing adult female populations with reduced density, and lower for nonreproducing females in populations with food supplementation. A pompilid wasp, Paracyphononyx funereus, was documented as a parasitoid of G. rafaelana, producing 50\%{\textendash}65\% mortality in adult females during winter, and 4{\textendash}5\% mortality in adult females during summer. The observed survival responses were correlated with variations in predation, while parasitism did not appear to be strongly density-dependent.

}, keywords = {article, articles, Geolycosa, also SEE , Geolycosa,predation, Geolycosa,resource limitation, journal, journals, predation,spider, spider, Geolycosa, wolf spider, SEE }, doi = {10.1007/BF00378453}, url = {files/bibliography/JRN00023.pdf}, author = {Marsha R. Conley} } @mastersthesis {51901, title = {Population regulation and prey community impact of Geolycosa rafaelana (Chamberlin) (Araneae: Lycosidae)}, year = {1984}, note = {//NMSU//NONE//}, month = {1984}, pages = {68}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {The influences of food supply and density on adult survival were examined in the burrowing wolf spider Geolycosa rafaelana (Lycosidae), using manipulations of spider populations on eight 400 sq m experimental plots. A total of 110 adult spiders were captured, weighed, marked, and returned to their burrows during April - May 1983. Treatments of (1) food supplementation, (2) density reduction, (3) food supplementation combined with density reduction, and (4) no manipulation (control) were applied to the eight populations, and adult survival and reproduction were monitored during May - October 1983. Population survival rates were higher for nonreproducing adult females in one population with reduced density, and lower for nonreproducing females in one population with food supplementation. A pompilid wasp, Paracyphononyx funereus, was discovered as a parasitoid of G. rafaelana, producing 50-65\% mortality in adult females during winter, and 4-5\% mortality in adult females during summer. Predation (as indicated by absence of adult remains in burrow) was significantly higher in populations receiving food supplementation and accounted for 0-100\% of the mortality in individual populations. The role of G. rafaelana as a structuring force in the arthropod community was examined with an experiment employing an additional eight 400 sq m plots. Adult spiders on these plots were censused during March 1983, and subsequently removed from four of the plots during June 1983. Spiders on the remaining four plots were left undisturbed and were monitored monthly for activity, during June - October 1983. Nocturnal ground-dwelling arthropods were sampled weekly, 29 June - 10 October, using pitfall traps on each plot. Ant colonies were censused on the eight plots in August 1983. Analyses of similarity in species composition, species diversity, and mean biomass indicated no consistent difference in arthropod community structure between control and removal plots. Additional comparisons for nine species of ants occurring on the plots disclosed no difference in colony densities on control versus removal plots.}, keywords = {dissertation, dissertations, Geolycosa, SEE , Geolycosa,food habits, spider, Geolycosa, spider, parasitism, spider, predation, spider, wolf spider,Geolycosa, theses, thesis}, author = {Marsha R. Conley} } @article {51914, title = {Polypay breed improvement}, journal = {Lamb and Wool Products}, volume = {1}, number = {5}, year = {1984}, month = {1984}, pages = {7-10}, abstract = {

While living with my family in New Zealand a few years ago, we experienced many new things. One of these. which should be of great significance to this group. was that the per capita consumption of lamb, hogget, and mutton was higher than that of any other meat. I asked why. After some investigation, I found that the retail price of lamb and hogget was less than that of any other meat --- including chicken. Then, we might suppose that although this would naturally stimulate sales. the New Zealand sheep farmer would soon go broke unless he got better prices. However, that also has not happened. Then, how can we account for this apparent paradox?

}, url = {/files/bibliography/264.pdf}, author = {Clarence V. Hulet} } @mastersthesis {51919, title = {Performance and diet quality of goats grazing creosotebush dominated rangeland and their effect on plant community}, year = {1984}, note = {//??//NONE//}, month = {1984}, pages = {83}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, goat, diet, goat, productivity, Larrea community, goat grazing, theses, thesis}, author = {Morrical, Daniel Gene} } @mastersthesis {51938, title = {Potential mediation of subterranean termites in infiltration, runoff, and erosional soil loss on a desert watershed}, year = {1983}, note = {//NMSU//NONE, LTER//updated 03/20/2008}, month = {1983}, pages = {137}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {The effects of subterranean termite activity on hydrologic responses from small plots of varying vegetal cover receiving simulated rainfall were investigated on a Chihuahuan desert watershed. Chlordane, a highly recalcitrant insecticide, was used as a chemical machanism for the elimination of termite activity. A spray nozzle infiltrometer was used to deliver an approximate 5 in/hr rainfall intensity for a duration of 45 minutes to each 1 m2 plot. Two simulated rain events were applied to each selected plot to emulate both dry and wet antecedent soil moisture conditions....These investigations demonstrated that under conditions of low vegetational density, characteristic of most arid and semi-arid ecosystems, the eradication or alteration of biological components of those ecosystems might initialize or accelerate desertification processes culminating in elevated system stress and lower productivity.}, keywords = {dissertation, dissertations, erosion,termite effects, hydrology,termite effects, infiltration,termite effects, insecticide,Chlordane, Larrea community,termite activity, runoff,termite effects, soil, erosional loss, soil,Chlordane treated, termite,hydrology, termite,infiltration, theses, thesis}, author = {Ned Z. Elkins} } @article {51939, title = {Pre-dispersal seed feeding insects of a desert legume, Astragalus nutallianus}, journal = {The Southwestern Naturalist}, volume = {28}, number = {4}, year = {1983}, note = {//NMSU//NONE//}, month = {1983}, pages = {466-469}, abstract = {

During the spring of 1979, we conducted surveys of the pre-dispersal seed-eating insect guild of loco weeds, Astraglus nutallianus D.C. Two alluvial plains (bajadas) separated by approximately 25 km, were surveyed. The bajadas are on the Mt. Summerford watersheds on the New Mexico State University Experimental Range, 40 km NNE of Las Cruces, N.M. On each site we classified the loco weeds into 5 relative density classes based on distance to nearest neighbor of the same species. Distance classes in meters were 0-0.5, 0.5-1.0, 1.0-5.0, 5.0-10.0 and 10.0-20.0. At least 10 plants in each of the density class areas were up rooted, place in plastic bags and transported to the laboratory. We recorded the number of plants of other species within a 1.5 m radius of each plant collected. All pods were stripped from each plant, and the total number of pods and the number of pods damaged by seed-eating insects were counted. A subsample of insect damaged and undamaged pods were opened and the number of seeds present in each was recorded. Another subsample was placed in containers to rear the larvae present. The plant, devoid of pods, was oven dried and weighed.

}, keywords = {article, articles, Astragalus,seed feeding insects, granivore, Astragalus, insect, foraging stategy,seed feeding, insect, seed feeding, journal, journals, plant, Astragalus, plant, locoweed, Astragalus}, url = {files/bibliography/83-SWNat-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @conference {51947, title = {Performance of beef cows on semidesert range in response to supplements containing sewage solids offered periodically throughout 5 years}, booktitle = {Journal of Animal Science}, volume = {57(Suppl 1)}, year = {1983}, month = {1983}, pages = {436}, abstract = {

Air-dried solids from primary sewage sludge were gamma-irradiated (1 megarad) and used as 50\% or more of d.m. in experimental range supplements (RS, 20-22\% crude protein) fed to beef cows in late gestation-early lactation during 92 {\textpm} 10 days each year for 5 years when forage lacked protein. Other cows in the same herd received no supplement (NONE) or cottonseed meal (CSM) at the same times. Intakes of RS or CSM were about .45 kg/hd in the first 3 years; .9 kg/hd for RS and CSM in the fourth year, and .45 kg/hd for CSM and .9 kg/hd for RS in the fifth year. Calf weights at weaning did not differ (P\>.25) in the first 3 years (NONE, 171; CSM, 179; and RS, 176 kg) but were increased (P\<.05) by CSM (192 kg) over RS (180 kg) or NONE (177 kg) in the last two years. Calf crops were increased 10 to 12\% over NONE by CSM during all 5 years and increased 11\% over NONE by RS during the first 3 years; but in the last 2 years (when RS intakes were .9 kg/hd) RS decreased calf crop 8\% below NONE. No evidence of toxicity was found in terms of symptoms: blood clinica profiles; heavy metals in blood, milk, or livers sampled yearly; liver mixed-function oxidase activity; or, histopathology of organs and tissues of cows at slaughter after 5 years. But RS diminished liver vitamin A when fed as sole diet to sheep and, apparently, RS exacerbated vitamin A deficiency in the cow herd during the two final breeding seasons.

}, keywords = {beef cows, long-term, range supplements, reproduction, sewage solids}, author = {Head, M.A. and Geoffrey Smith and C.H. Herbel and H.E. Kiesling and Urquhart, N.S.} } @conference {51951, title = {Part-year confinement and early weaning of range cattle}, booktitle = {36th Annual Meeting, Society for Range Management}, year = {1983}, month = {1983}, pages = {No. 291}, keywords = {confinement, range cattle, weaning}, author = {C.H. Herbel and Wallace, J.D.} } @article {51950, title = {Principles of intensive range improvements}, journal = {Journal of Range Management}, volume = {36}, number = {2}, year = {1983}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {March 1, 1983}, pages = {140-144}, abstract = {

Our expanding population is demanding more productivity and other contributions from our rangelands. Range science is concerned with the plants, animals, soils, and waters on rangelands, particularly the interaction of these factors. Native plant communities should only be used as guides to determine site potential. Extensive practices on rangelands include manipulation of animals and burning. Intensive practices include control of unwanted plants, revegetation, and fertilization. When properly conducted, intensive manipulation practices often result in much higher production than before treatment. Each land manager determines the desired level of productivity based on economic, cultural, political, and social factors, and the availability of technology. The most effective method for control of unwanted plants varies with the sites, the species, and the degree of infestation. Revegetation may be required where desirable vegetation has been depleted by past grazing abuses, droughts, and encroachment of unwanted plants. Water is generally the primary factor limiting plant growth but when that need has been satisfied, additional plant nutrients such as nitrogen and phosphorus may be useful. The more costly practices are riskier and require higher management inputs, but the potential benefits are great. With changing technology or favorable economic conditions, the range manager may decide to intensify his range improvement efforts.

}, url = {/files/bibliography/237.pdf}, author = {C.H. Herbel} } @article {51958, title = {Phenological patterns of Chihuahuan Desert plants in relation to the timing of water availability}, journal = {Journal of Ecology}, volume = {71}, year = {1983}, note = {//LOCAL//NONE//}, month = {1983}, pages = {427-436}, abstract = {Phenology, density, and cover of plant species occurring in a single Chihuahuan desert habitat were studied for 2 years as a function of habitat moisture with the objective of relating plant species diversity to water partitioning. Much of the temporal variation in growth and phenology between species was correlated with differences in life form and photosynthetic pathway. The annual plant species consisted of a winter-spring group containing only species with the C3 photosynthetic pathway which utilize the moisture from frontal storms of winter, and a summer group containing a large majority of species with the C4 photosynthetic pathway which utilize the moisture from convectional storms of late summer. The perennial plant species consisted of C3 and C4 forbs, C4 grasses, C3 shrubs and CAM shrubs. The C3 forbs showed greatest activity in spring or autumn while the C4 forbs and grasses were most active in the summer and autumn. The C3 shrubs and CAM shrubs were active at various times from spring to autumn and not as dependent as the other groups on available soil moisture. There was above average precipitation in late summer and autumn during the first year of study and an early and prolonged drought in autumn of the second year. Some species of perennial C3 forbs and C4 grasses responded to the abundant precipitation of the first autumn with increased density or cover in the second year, but there was little change in the shrub species. The drought in the second year caused a reduction in the number of species and individuals of both C3 and C4 annual plants. The results suggest that the high species diversity in this habitat is partly a result of the different life form and photosynthetic pathway groups, each being adapted for utilizing a particular phase of the seasonally and yearly variable water.}, keywords = {article, articles, journal, journals, phenology, annual plants, phenology, photosynthetic pathway, photosynthetic pathway, plant, phenology, water availability}, author = {P. R. Kemp} } @article {51997, title = {Patterns of prehistoric land use in Dona Ana County, New Mexico}, year = {1982}, note = {//??//NONE//}, month = {1982}, institution = {New Mexico State University}, address = {Las Cruces, New Mexico}, keywords = {book, books, chapter, chapters, history, prehistoric land use, report, reports}, isbn = {Cultural Resources Management Division Report 471}, author = {Duran, M. S.} } @article {52010, title = {Photosynthetic pathway types of evergreen rosette plants (Liliaceae) of the Chihuahuan Desert}, journal = {Oecologia}, volume = {55}, year = {1982}, note = {//LOCAL//NONE//}, month = {1982}, pages = {149-156}, abstract = {Diurnal patterns of CO2 exchange and titratable acidity were monitored in sex species of evergreen rosette plants growing in controlled environment chambers and under outdoor environmental conditions. These patterns indicated that two of the species, Yucca baccata and Y. torreyi, were constitutive CAM plants while the other species, Y. elata, Y. campestris, Nolina microcarpa, and Dasylirion wheeleri, were C3 plants. C3 species did not exhibit CAM when grown in any of several different temperature, photoperiod, and moisture regimes. Both photosynthetic pathway types appear adapted to desert environments and all species show environmentally induced changes in their photosynthetic responses consistent with desert adaptation. The results of this study do not indicate that changes in the photosynthetic pathway type are an adaptation in any of these species.}, keywords = {article, articles, Dasylirion, photosynthetic pathway, journal, journals, Liliaceae, photosynthetic pathway, Nolina, photosynthetic pathway, photosynthetic pathway, Liliaceae, plant, Dasylirion, plant, Nolina, plant, photosynthetic pathway, plant, Yucca, Yucca, photosynthetic pathway}, author = {P. R. Kemp and Pietra E. Gardetto} } @article {52057, title = {Photosynthesis, growth and ultraviolet irradiance absorbance of Cucurbita pepo L. leaves exposed to ultraviolet-B radiation (280-315 nm)}, journal = {Plant Physiology}, volume = {67}, year = {1981}, month = {1981}, pages = {120-124}, url = {/files/bibliography/204.pdf}, author = {Sisson, W.B.} } @mastersthesis {52059, title = {Population dynamics of grass-forb complexes on a semidesert range and some demographic aspects of James rushpea (Hoffmanseggia jamesii Torr. and Gray)}, year = {1981}, note = {//USDA//NONE//}, month = {1981}, pages = {169}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {Dynamics of forbs and important grass species from 1915 to 1974 were investigated utilizing records from long-term charted quadrats on the Jornada Experimental Range, USDA, SEA-AR, in southern New Mexico. A short-term demographic study focusing on longevity and age-structure of the perennial forb, James rushpea (Hoffmanseggia jamesii), was also conducted using a technique for counting growth increments. Interesting results were obtained by the study of some demographic aspects of James rushpea. A maximum number of 9 growth increments was found for this species. A highly significant correlation (P<.001) was found between the number of growth increments and the cormlike base circumference (cm.). Age-structure of this species was described by two patterns: A J-shaped pattern on protected and highly disturbed sites, and an inverse J-shaped pattern on lightly grazed sites.}, keywords = {demography, Hoffmanseggia, demography,grass-forb complexes, dissertation, dissertations, grass-forb complex,population dynamics, Hoffmanseggia,demography, plant,James rushpea,Hoffmanseggia, population dynamics,grass-forb, theses, thesis}, author = {Suliman, Mustafa Mohamed} } @article {52066, title = {Postweaning growth and carcass characteristics of crossbred steers}, journal = {Proceedings, Western Section, American Society of Animal Science}, volume = {32}, year = {1981}, note = {//NMSU//NONE//}, month = {1981}, pages = {303-306}, abstract = {Steers of various percentages of Brangus (B), Hereford (H) and Charolais (C) breeding were evaluated for the effects of individual genotype, maternal breed and breeding system on postweaning growth and carcass characteristics.}, keywords = {article, articles, cattle, genetics, cattle, management, cattle, nutrition, cattle,productivity, genetics, cattle, journal, journals}, author = {Jamie Fred Williams and B. J. Rankin} } @article {52069, title = {Population age structure and its relationship to the maintenance of a semidesert grassland undergoing invasion by mesquite}, journal = {The Southwest Naturalist}, volume = {26}, year = {1981}, month = {1981}, pages = {13-22}, url = {/files/bibliography/209.pdf}, author = {R. G. Wright and G.M. Van Dyne} } @mastersthesis {52081, title = {Predaceous microathropods as potential regulators of microbial grazing during litter decomposition in a Chihuahuan desert ecosystem}, year = {1980}, note = {//??//NONE//}, month = {1980}, pages = {45}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {decomposition, litter, decomposition,microarthropods, dissertation, dissertations, litter decomposition, microarthropod,decomposition, microathropod,microbial grazing, microbial grazing, theses, thesis}, author = {Ned Z. Elkins} } @mastersthesis {52085, title = {Pronghorn antelope studies on the Jornada del Muerto}, year = {1980}, note = {//USDA, NMSU//NONE//}, month = {1980}, pages = {50}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Pronghorn antelope (Antilocapra americana) were studied during summer and fall 1979, and winter and spring 1980 at the Jornada Del Muerto Plains, 23 miles north of Las Cruces, New Mexico, to determine the actual locations of pronghorns, their numbers, vegetations utilized and seasonal movements. Pronghorn numbers were determined by direct ground counts and aerial surveys. The maximum number of pronghorns observed in one day, without duplication, was considered the total count. A total of 42 and 68 pronghorns were counted in 1979 and 1980, respectively. Does began to have kids about the 5th of May and stopped the 18th of May in 1980. High kid production in 1979 (1.08 kids/adult female) occurred along with above-average precipitation (39.65 cm), which provided enough forage for pregnant females. The Jornada Experimental Range and the College Ranch contained a northern and southern pronghorn herd. The northern herd moved to the south in early winter and both herds wintered close to each other, mainly in Pasture 8 of the College Ranch. The pronghorn population was scattered in smaller groups during the remainder of the year. The study indicated that pronghorns restricted their distribution to the grassland vegetational complex within the study area. Currently the grassland complex comprises 29.4\% of the total vegetation, but more than 75\% of the pronghorn observations were recorded in grasslands. The size of the grassland complex and low annual rainfall are the main factors for the slow increase in pronghorn numbers. Poachers and predators possibly have a slight effect while fences did not seem to be a barrier restricting the movement of pronghorns within the study area.}, keywords = {Antilocapra, reproduction, Antilocapra,distribution, dissertation, dissertations, mammal, Antilocapra, mammal, pronghorn antelope, Antilocapra, pronghorn antelope, SEE , theses, thesis}, author = {Ghaly, Magdi Yousif} } @proceedings {52089, title = {Present status of electronic identification}, year = {1980}, month = {November 3-7, 19}, pages = {20 }, publisher = {Los Alamos Scientific Lab, Preprint LA-UR-80-3166}, address = {Louisville, KY}, abstract = {Electronic identification of animals was first seriously discussed at a USAHA meeting in Miami in 1972 when Henri Majeau of Boeing Aircraft Company discussed his design, John Hanton of Montana State discussed his concept and Dale Holm discussed a Los Alamos Scientific Laboratory (LASL) design. At subsequent meetings of the USAHA, reports have described the technical progress of the LASL design as particular problems were surmounted. By the end of 1977, implantable identification had been demonstrated. It was felt that most of the significant technical problems had been overcome and commercial manufacturers could be expected to enter into the development and testing. An announcement was made in the Commerce Business Daily in January 1978 to stimulate commercial interest in manufacturing equipment for a field test. As reported last year, this resulted in a letter contract that was signed in September 1979 with Raytheon Service Company to produce equipment for the field test. A LASL system was installed at the USDA Jornada Experimental Range at Las Cruces, New Mexico, in the fall of 1979 to demonstrate the capability of the LASL system in a field environment. Subsequent negotiations with Raytheon resulted in withdrawal of their bid. With this development a reevaluation of the program was made by the USDA/APHIS and LASL.}, keywords = {electronic identification, status}, url = {/files/bibliography/181.pdf}, author = {Holm, D.M. and Araki, C.T. and Landt, J.A. and Sanders, W.M. and Seawright, G.L. and D.M. Anderson} } @book {52098, title = {Predicting primary productivity for forest and desert ecosystem models}, series = {Predicting Photosynthesis for Ecosystem Models}, volume = {Volume II}, year = {1980}, note = {//NMSU//US-IBP//ProCite field[6]: In}, month = {1980}, pages = {169-207}, publisher = {CRC Press, Inc.}, organization = {CRC Press, Inc.}, address = {Boca Raton, Florida}, abstract = {A major goal of the Analysis of Ecosystems Program of the U.S. International Biological Program (IBP) was to understand how entire ecosystems function so that their behavior, particularly in response to man-made stresses, might be predictable. A significant part of the research was focused on increasing our knowledge of productivity in natural ecosystems. Productivity was broadly defined so as to include not only energy flux within the trophic structure of the ecosystem but also the attendant water and nutrient fluxes. A major component of the research design in each of the various IBP Biome projects (i.e., grassland, desert, tundra, and deciduous and coniferous forests) was the development of ecosystem-level models of energy and material fluxes.}, keywords = {book, books, carbon allocation, Larrea, carbon-balance paradigm, chapter, chapters, desert, ecosystem models, forest, Larrea,productivity, model, primary productivity, Larrea, model, primary productivity, Pinus, model,carbon-balance, model,growth, model,primary productivity, Pinus,productivity, primary production,model, report, reports, shrub,model}, author = {J. F. Reynolds and Strain, B. R. and Gary L. Cunningham and Knoerr, K. R.}, editor = {Hesketh, J. D. and J. W. Jones (eds.)} } @mastersthesis {52115, title = {Postweaning growth and reproductive performance of Brangus and crossbred heifers}, year = {1980}, note = {//NMSU//NONE//}, month = {1980}, pages = {47}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {A study utilizing 131 crossbreed and Brangus heifers was conducted during two years at the New Mexico State University, College Ranch. Postweaning growth and reproductive traits were evaluated for effects of year, breed of heifer, and breed x year interactions.}, keywords = {cattle, genetics, cattle, reproduction, cattle,productivity, dissertation, dissertations, theses, thesis}, author = {Willemsma, Hank A.} } @mastersthesis {52118, title = {Phenological development and impact of season and intensity of defoliation on Sporobolus flexuosus and Bouteloua eriopoda}, year = {1980}, note = {//NMSU//NONE//}, month = {1980}, pages = {110}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The objectives of this study were to determine how eight seasonal defoliation patterns affect regrowth of dry matter yield and basal diameter of mesa dropseed (Sporobolus flexuosus [Thrub.] Rhydb.) and black grama (Bouteloua eriopoda [Torr.] Torr.); determine how these defoliation patterns affect the reproductive potential of black grama; quantify seasonal phenological stages of growth in both species; and interpret the data in terms of management application. Regrowth and basal diameter of both species clipped to remove 30 percent the first year during vegetative growth had increased after two growing seasons. Therefore, for continued forage production, light use prior to floral development is recommended. Regrowth, basal diameter, and stolon numbers increased over two growing seasons in black grama plants clipped to simulate light use at dormancy. Therefore, light use of black grama during the winter is encouraged.}, keywords = {Bouteloua, defoliation, Bouteloua,management, Bouteloua,phenology, cattle grazing, Bouteloua, cattle grazing, Sporobolus, dissertation, dissertations, grass, Bouteloua, grass, Sporobolus, grassland, management, grassland, reproduction, productivity,grassland, Sporobolus, defoliation, Sporobolus,management, Sporobolus,phenology, theses, thesis}, author = {Young, Steve A.} } @proceedings {52123, title = {Production patterns of Larrea in the northern Chihuahuan Desert}, year = {1979}, note = {//??//NONE//ProCite field[6]: In}, month = {1979}, pages = {139-150}, publisher = {Centro de Investigacion en Quimica Aplicada}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, Larrea,productivity, proceeding, proceedings, productivity,Larrea, shrub, Larrea}, author = {J. Ludwig and P. Flavill}, editor = {Campos-Lopez, E. and Mabry, T. J. and Fernandez-Tavizon, S. (eds.)} } @conference {52132, title = {Photosynthesis, growth, and UV irradiance absorbance of Cucurbita pepo leaves exposed to UV-B radiation (280-315 nm)}, booktitle = {Western Section of the American Society for Plant Physiology}, year = {1979}, month = {1979}, address = {Reno, NV}, author = {Sisson, W.B.} } @article {52140, title = {Postweaning growth and reproductive performance of Hereford, Brangus and reciprocal crossbred heifers}, journal = {Proceedings, Western Section, American Society of Animal Science}, volume = {30}, year = {1979}, note = {//NMSU//NMSU//}, month = {1979}, pages = {28-33}, abstract = {Hereford, Brangus and reciprocal crossbred heifers from two distinct New Mexico environments and three consecutive calf crops were evaluated for the effects of year, ranch source (environment), breed of sire, breed of dam, heterosis and residual genotype X environment interactions on postweaning growth and reproductive performance.}, keywords = {article, articles, cattle, genetics, cattle, management, cattle, productivity, cattle, reproduction, journal, journals}, author = {J. A. Winder and B. J. Rankin} } @mastersthesis {52141, title = {Postweaning growth and reproductive performance of Hereford, Brangus, and reciprocal crossbred heifers}, year = {1979}, note = {//NMSU//NONE//}, month = {1979}, pages = {63}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Hereford, Brangus and reciprocal crossbred heifers from two distinct New Mexico environments were evaluated for the effects of year, ranch source, breed of sire, breed of dam, heterosis and various interaction components on postweaning growth and reproductive traits.}, keywords = {cattle, genetics, cattle, management, cattle, productivity, cattle, reproduction, dissertation, dissertations, theses, thesis}, author = {J. A. Winder} } @article {52170, title = {Primary productivity and water use in native forest, grassland, and desert ecosystem}, journal = {Ecology}, volume = {59}, number = {6}, year = {1978}, note = {//NMSU, USDA//US-IBP//}, month = {1978}, pages = {1239-1247}, abstract = {The relationship between aboveground net primary production (ANPP) and water use varied significantly among ecosystem types. For both hot deserts and shortgrass prairie-cold deserts which are water limited, ANPP is linearly related to annual water use above a minimum amount of water, estimated at 38 to 170 mm, respectively, needed annually to sustain each system. Once the minimum water to sustain ANPP is reached, ANPP increases an estimated 0.38 g and 1.09 g per 1000 g of additional water in the hot desert and the shortgrass prairie-cold desert. In forest systems not water stressed, ANPP was not related to water use. For grasslands representing a gradient from water stressed toward not water stressed, ANPP correspondingly declined per unit of water used. Classically evaluating water-use efficiency as annual ANPP divided by annual evapotranspiration, forests are the most efficient, 0.9 to 1.8 g ANPP/1000 g water, followed by shortgrass prairie, 0.2 to 0.7, then hot deserts, 0.1 to 0.3.}, keywords = {article, articles, Bouteloua,productivity, evapotranspiration, grassland, forests, grass,Bouteloua, grassland, evapotranspiration, grassland, primary production, journal, journals, primary production, grassland, productivity, grassland, water-use efficiency}, author = {Webb, Warren and Szarek, Stan and W. K. Lauenroth and Kinerson, Russell and Smith, Milton} } @article {52228, title = {Primary production and carbon allocation in creosotebush}, year = {1975}, note = {//??//US-IBP//}, month = {1975}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, Larrea,carbon allocation, Larrea,primary production, primary production,Larrea, report, reports}, isbn = {Research Memorandum 75-9}, author = {Gary L. Cunningham and J. P. Syvertsen and Feather, T. V.} } @article {52267, title = {Populations and trophic structure of a desert grassland invertebrate community}, year = {1974}, note = {//USDA//US-IBP//}, month = {1974}, institution = {Colorado State University}, address = {Ft. Collins, Colorado}, keywords = {book, books, chapter, chapters, grassland,insect biomass, grassland,insect populations, insect biomass, invertebrate community, invertebrate populations, invertebrate, see ALSO , invertebrate,trophic structure, report, reports}, isbn = {Technical Report 248}, author = {M. A. Ellstrom and Watts, J. G.} } @article {52282, title = {Primary production on the Jornada site for 1972}, year = {1974}, month = {1974}, pages = {29}, institution = {International Biological Program, Grassland Biome Technical Report 249}, keywords = {Jornada, popular publication, production}, author = {Pieper, Rex D. and C.H. Herbel} } @mastersthesis {52299, title = {Populations and trophic structure of a desert grassland invertebrate community}, year = {1973}, note = {//USDA//US-IBP//}, month = {1973}, pages = {100}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Invertebrate populations and biomass were measured on the Jornada desert grassland study site, United States International Biological Program, Grassland Biome, over a period from July 1970 to October 1972. Samples were taken at appproximately monthly intervals from both grazed and ungrazed treatments using randomly placed quick traps and a D-Vac vacuum insect collector....Supplementary sampling with the sweep net, pitfall trap, and light trap revealed that quick trap sampling was inefficient for some taxa. At least five invertebrate families which were taken by supplementary methods were entirely absent from quick trap samples.}, keywords = {dissertation, dissertations, grassland, invertebrate biomass, grassland, invertebrate populations, invertebrate community, invertebrate, biomass, invertebrate, populations, invertebrate, see ALSO , invertebrate,trophic structure, theses, thesis}, author = {M. A. Ellstrom} } @mastersthesis {52311, title = {Physiological and ecological aspects of aestivation of recently metamorphosed desert anurans}, year = {1973}, note = {//NMSU//NONE//}, month = {1973}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {Recently metamorphosed Scaphiopus hammondi, Bufo cognatus and B. debilis, collected from a flooded playa in southern New Mexico, were allowed to burrow within soil containers (in the laboratory) which simulated natural winter conditions. Standard rates of oxygen consumption (QO2) obtained at 15 C, indicated that in aestivating S. hammondi juveniles, QO2 was 25\% of that obtained for active toadlets. Scaphiopus juveniles were the most successful burrowers, in the laboratory containers, with a 60\% overwintering survival; both B. cognatus and B. debilis were poor burrowers, with none surviving. Body water decreased approximately 13\% and fat reserves by more than 33\% in overwintering S. hammondi toadlets. Juvenile S. hammondi lose water to the dry desert soil (at greater than 35 bars), and metabolize body lipids at rates which allow the majority to remain burrowed for at least 18 months.}, keywords = {amphibian, also SEE , anuran, aestivation, anuran, ecology, anuran, physiology, Bufo, dissertation, dissertations, Scaphiopus, theses, thesis, toad, SEE }, author = {Kenneth H. Meltzer} } @article {52325, title = {Pattern and process in grassland bird communities}, journal = {Ecological Monographs}, volume = {43}, year = {1973}, month = {1973}, pages = {237-270}, abstract = {Variations in abundance and distribution of bird species and avifaunal and community organization at regional, local, and within-plot levels were studied during 1969 and 1970 at a shortgrass prairie in Colorado and during 1970 at six additional International Biological Program (IBP) grassland sites.}, keywords = {article, articles, journal, journals}, author = {J.A. Wiens} } @mastersthesis {52327, title = {Physiology of the desert millipede Orthoporus ornatus}, year = {1973}, note = {//??//NONE//}, month = {1973}, school = {University of New Mexico}, type = {M.S. Thesis}, address = {Albuquerque, New Mexico}, keywords = {dissertation, dissertations, insect,millipede,Orthoporus, insect,Orthoporus,physiology, physiology,Orthoporus, theses, thesis}, author = {Wooten, R. C.} } @article {52333, title = {Pollen study of some Holocene alluvial deposits in Dona Ana County, southern New Mexico}, journal = {The Texas Journal of Science}, volume = {24}, year = {1972}, note = {//LOCAL//NONE//}, month = {1972}, pages = {203-220}, abstract = {The fossil pollen spectra of 3 radiocarbon dated alluvial deposits at Gardner Spring, New Mexico were studied. The oldest of these sections spans the time from 5,000 to less than 4,000 radiocarbon years B.P. and indicates a desert shrub to grassland transition. This finding indicates that the dry altithermal of the Bryan-Antevs model may have been a reality in southern New Mexico. The 2nd deposit dated at younger than 2300 radiocarbon years indicates a drying trend that probably was not extreme. The 3rd deposit studied is younger than 1100 radiocarbon years and seems to indicate conditions very similar to those at the time end of the oldest cycle of deposition and grassland conditions.}, keywords = {article, articles, fossil pollen, geomorphology,alluvial deposits,pollen, Holocene,pollen, journal, journals, pollen, Holocene alluvial deposits, pollen, radiocarbon dating, radiocarbon dating,pollen, soil,alluvial deposits}, author = {Freeman, C. E.} } @article {52341, title = {Proteolytic activity of soil microorganisms}, year = {1972}, note = {//??//US-IBP//}, month = {1972}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, chapter, chapters, proteolytic activity,microorganisms, report, reports, soil microorganisms}, isbn = {Research Memorandum 72-42}, author = {R. T. O{\textquoteright}Brien} } @conference {52343, title = {Primary production of a desert grassland ecosystem}, booktitle = {25th Annual Meeting, Society for Range Management}, year = {1972}, month = {1972}, pages = {8}, keywords = {desert grassland ecosystem}, author = {Pieper, Rex D. and C.H. Herbel and J. W. Russell} } @article {52346, title = {Preliminary producer data synthesis, 1970, Comprehensive Network Sites}, year = {1972}, note = {//??//US-IBP//}, month = {1972}, institution = {Colorado State University}, address = {Ft. Collins, Colorado}, keywords = {book, books, chapter, chapters, producers, report, reports}, isbn = {Technical Report 161}, author = {P. G. Risser} } @article {52364, title = {Physiological responses to temperature in the patch-nosed snake, Salvadora hexalepis}, journal = {Herpetologica}, volume = {27}, number = {3}, year = {1971}, note = {//NMSU//NONE//}, month = {1971}, pages = {289-295}, abstract = {

Salvadora hexalepis had a mean preferred body temperature in the laboratory of 33.0 C, a mean critical thermal minimum of 7.0 C, and a mean critical thermal maximum of 43.8 C. Oxygen consumption and heart rate increased with temperature, and greatest changes in these parameters at high and low temperature extremes. Cardiac and metabolic responses area what would be predicted for a reptile the size of S. hexalepis. A wide range of thermal tolerance is suggested as an important adaptation for a snake that is primarily a lizard predator.

}, keywords = {article, articles, journal, journals, snake, patch-nosed snake, Salvadora, snake, physiology, snake, Salvadora, physiology}, url = {files/bibliography/71-Herpetologica-Whitford.pdf}, author = {Jacobson, Elliot R. and Walter G. Whitford} } @article {52369, title = {Primary producers, invertebrates, birds, and decomposers on the Jornada site, 1971}, year = {1971}, note = {//??//US-IBP//}, month = {1971}, institution = {Colorado State University}, address = {Ft. Collins, Colorado}, keywords = {bird, book, books, chapter, chapters, decomposition, invertebrates, primary producers, report, reports}, isbn = {Technical Report 200}, author = {Pieper, Rex D. and M. A. Ellstrom and E.E. Staffeldt and Ralph J. Raitt} } @article {52370, title = {Physiological responses to temperature in the horned lizards Phrynosoma cornutum and Phrynosoma douglassi}, journal = {Copeia}, volume = {3}, year = {1971}, note = {//LOCAL//NONE//}, month = {1971}, pages = {498-504}, abstract = {

In the laboratory, Phrynosoma cornutum and Phrynosoma douglassii from central New Mexico had mean preferred body temperatures of 38.5 C and 35 C respectively.... Differences in the oxygen pulse values of these species at high and low temperature extremes indicate differences in the cardiac output and efficiency. It is suggested that P. douglassii may have a more efficient transport of oxygen by the respiratory pigments at low temperatures than P. cornutum.

}, keywords = {article, articles, journal, journals, lizard,physiology, lizard,thermoregulation, Phrynosoma, Phrynosoma,thermoregulation, reptile, Phrynosoma, reptile,horned lizard}, doi = {10.2307/1442447 }, url = {files/bibliography/71-Copeia-Whitford.pdf}, author = {Abelardo Escobar Prieto and Walter G. Whitford} } @proceedings {52374, title = {Plant community structure}, year = {1971}, note = {//USDA//US-IBP//NMSU library QH541.5 .P7 .P74//ProCite field[6]: In}, month = {September 1, 197}, pages = {41-58}, publisher = {Colorado State University}, address = {Colorado State University, Fort Collins, Colorado}, abstract = { The 1970 field season data show that 65\% of the aboveground plant biomass on the Grassland Biome study sites was composed of grasses and that the tribes Andropogoneae and Chlorideae and the family Compositeae contribute well over half the total live biomass. The Hays, Osage, Bison, and Bridger Network Sites have bunchgrasses as the dominant growth form, while Jornada, Pantex, and Pawnee have mostly sod grasses. Dickinson and Cottonwood have a substantial representation of both growth forms. If the Network Sites are ordinated by either floral or vegetational similarities, the resulting configurations are very similar and closely approximate a site ordination based on environmental variables. There appears to be a general increase in phenological diversity with an increase in the amount of live standing crop. The concepts of pattern, species diversity, and aerial cover were evaluated on only a few sites, so biome wide comparisons were not possible. Phenology was measured throughout the 1970 growing season, but the interpretation of these data has proved difficult. Certain elementary characteristics such as height of vegetation, and proportion of warm and cool season grasses, showed a consistent relationship across the network. However, one of the most interesting aspects of the grassland structural data is the fact that many characteristics do not show a uniform response, indicating the multitude of adaptive strategies employed within the grassland ecosystem.}, keywords = {abstract, abstracts, biomass,grassland, conference, conference proceedings, conferences, grassland community, structure, proceeding, proceedings}, author = {P. G. Risser}, editor = {Norman R. French} } @proceedings {52381, title = {Pattern and process in grassland bird communities}, year = {1971}, note = {//USDA//US-IBP//NMSU library QH541.5 .P7 .P74//ProCite field[6]: In}, month = {September 1, 197}, pages = {147-212}, publisher = {Colorado State University}, address = {Colorado State University, Fort Collins, Colorado}, abstract = { Data collected during 1969 and 1970 in the U.S. IBP Grassland Biome Program are synthesized to examine patterns and processes characterizing breeding bird populations and communities in grasslands, with the overall intent of clarifying the role of birds as consumers in grassland ecosystems.}, keywords = {abstract, abstracts, Aves community, Aves community, grassland, conference, conference proceedings, conferences, grassland, bird communities, grassland,bird community, proceeding, proceedings}, author = {J.A. Wiens}, editor = {Norman R. French} } @article {52398, title = {Preliminary report on sampling of primary producers, invertebrates, and decomposers on the Jornada site, 1970}, year = {1970}, note = {//??//US-IBP//}, month = {1970}, institution = {Colorado State University}, address = {Ft. Collins, Colorado}, keywords = {book, books, chapter, chapters, decomposition, invertebrates, primary producers, report, reports}, isbn = {Technical Report 105}, author = {Pieper, Rex D. and Cannaughton, M. and Fitzenrider, R.} } @article {52423, title = {Performance of hereford and Santa Gertrudis cattle on an arid New Mexico range}, year = {1969}, month = {May 1, 1969}, pages = {15 }, institution = {USDA, Agricultural Research Service}, address = {Las Cruces, NM}, abstract = {The dominant breed of beef cattle on the arid rangelands of Southwestern United States is Hereford. Cattle with some Zebu (Brahman) breeding may be better adapted to the hot, arid environment of this area. Santa Gertrudis was selected as a breed in this latter category. An 8-year-study of calf weaning weights and percentage calf crop weaned and a 3-year-study of blood composition of cows of these two breeds was conducted on the Jornada Experimental Range, 25 miles north of Las Cruces, New Mexico.}, keywords = {hereford, New Mexico range, performance, Santa Gertrudis}, url = {/files/bibliography/120.pdf}, author = {Nelson, A.B. and Holland, L.A. and C.H. Herbel} } @mastersthesis {52441, title = {Phenology of desert ephemerals in southern New Mexico}, year = {1968}, note = {//LOCAL//NONE//}, month = {1968}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {During the spring and summer of 1967, phenology and occurrence patterns of ephemerals were observed on selected desert mesa sites east of Las Cruces, New Mexico. Twelve 4.5 ft. square quadrats, located at three elevations (4400{\textquoteright}, 4600{\textquoteright}, 5000{\textquoteright}) were read and mapped bi-monthly. Seedling development, floral bud formation, flowering, fruit formation, and death were recorded for all plants in each quadrat. No "spring" ephemerals were present on the plots in 1967. This was predicted because 1966-1967 late fall-early winter moisture was virtually absent. However, 1967-1968 late fall-early winter rains caused the plots to exhibit heavy growth of spring ephemerals. The appearance of summer ephemerals was closely correlated with summer rains in 1967. Phenological diagrams for four groups of plants were constructed illustrating differences in phenology.}, keywords = {dissertation, dissertations, ephemeral,phenology, phenology,ephemerals, theses, thesis}, author = {Shiffler, Wendell J.} } @article {52443, title = {Physiological responses to temperature and desiccation in the endemic New Mexico plethodontids, Plethodon neomexicanus and Aneides hardii}, journal = {Copeia}, volume = {2}, year = {1968}, note = {//LOCAL//NONE//}, month = {1968}, pages = {247-251}, abstract = {

Measurements of the critical maximum (CTM), oxygen consumption, and heart rate of Plethodon neomexicanus and Aneides hardii were made for comparison with similar data for other members of the family Plethodontidae. At an acclimation temperature of 20 C, the mean CTM for A. hardii was 33.3 C, and for P. neomexicanus, 33.5 C. Mean oxygen consumption increased from 30.9 u1/g/hr at 5 C to 93.9 u1/g/hr at 25 C in A. hardii and from 35.4 u1/g/hr at 5 c to 60.9 u1/g/hr at 25 C in P. neomexicanus. The metabolism-temperature (M-T) curve for P. neomexicanus was similar to that of Desmognathus quadramaculatus, and eastern plethodontid, but the M-T curve of A. hardii was more comparable to that of a lunged salamander. Heart rate increase directly with temperature in both species. The mean heart rate increased from 22/min at 10 C to 64/min at 25 C in A. hardii and from 24/min at 10 C to 73/min at 25 C in P. neomexicanus. The low CTM recorded for these species may be related to the low temperatures characteristic of their microhabitat. The difference in M-T curves in these species may reflect differences in surface area-mass relationships resulting in differences in cutaneous gas exchange.

}, keywords = {amphibian, Aneides, amphibian, physiology, amphibian, Plethodon, amphibian,desiccation, amphibian,salamander,Aneides, amphibian,salamander,Plethodon, Aneides,physiology, article, articles, journal, journals, physiology, amphibian, Plethodon,physiology, salamander, also SEE }, doi = {10.2307/1441750 }, url = {files/bibliography/68-Copeia1_Whitford.pdf}, author = {Walter G. Whitford} } @mastersthesis {52452, title = {Physiological responses to temperature in the horned lizards Phrynosoma cornutum and Phrynosoma douglassi}, year = {1967}, note = {//LOCAL//NONE//}, month = {1967}, pages = {25}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Physiological responses to temperature were studied in Phyrnosoma cornutum and P. douglassi.... The results of these studies indicate that the wide range of distribution of P. douglassi is in part due to its wide zone of thermo-mobility and low CTMin as compared to P. cornutum. Differences in the oxygen pulse values of the two species at two temperature extremes differences in the cardiac output and efficiency. P. douglassi may have a more efficient mechanism for the transport of oxygen by the respiratory pigments of the blood at low temperatures than P. cornutum.}, keywords = {dissertation, dissertations, lizard,physiology, lizard,thermoregulation, Phrynosoma, Phrynosoma,thermoregulation, reptile, Phrynosoma, reptile,horned lizard, theses, thesis}, author = {Abelardo Escobar Prieto} } @article {52463, title = {Periodic sedimentation and soil formation on an alluvial-fan piedmont in southern New Mexico}, journal = {Soil Science Society of America Proceedings}, volume = {30}, number = {2}, year = {1966}, note = {//LOCAL//NONE//}, month = {1966}, pages = {261-268}, abstract = {Gullies cut in alluvial-fan piedmont deposits at the southern end of the Jornada del Muerto basin, New Mexico, reveal evidence of periodic sedimentation and soil formation. The gullies show a succession of four major sediments, each of which has a distinct soil, indicating that each period of sediment deposition was followed by a period of stability and soil formation. The two youngest sediments are restricted primarily to a broad drainageway position and have soils with relatively weak B and carbonate horizons. The next older sediment, buried in the broad drainageway, has a soil that has prominent textural B and carbonate horizons and that emerges at the land surface on either side of the drainageway. Towards the basin axis the sediments thin and there is mergence of the land-surface soil with the oldest soil exposed in the gullies. The land-surface soils overlie much older soils and in places are so thin that the buried soils must be considered in classification of the land-surface soils. Gradual mergence zones of major sediments can conceal complexities greater than might be suggested by the generally smooth relief. Filling of channels in old sediments by younger sediments can cause prominent and abrupt soil changes no suggested by the smooth relief and uniform slope which crosses the soil boundaries. These phenomena are especially prevalent in and adjacent to drainageways an din areas of thinning of major sediments.}, keywords = {article, articles, geomorphology, alluvial-fan piedmont, geomorphology,sedimentation, geomorphology,soil formation, journal, journals, soil formation}, author = {L. H. Gile and J. Hawley} } @proceedings {52483, title = {Performance of hereford and Santa Gertrudis cattle on arid range in southwestern United States}, year = {1965}, month = {1965}, pages = {F-19--F-20}, abstract = {The performance of Hereford and Santa Gertrudis cattle on the Jornada Experimental Range was studied for 3 years. The test herd consisted of 15 cows of each breed stocked separately on two pastures of about the same shape. They were rotated between these two pastures annually. The activities of one Hereford cow and one Santa Gertrudis cow were noted for a 24-hr period every 4 weeks during the 3-yr period. A cow from each breed was observed during the daylight hours each 28-day period for the first 17 months. Generally, Herefords spent more time grazing (42.9\% v. 37.2\%), standing-ruminating (8.6\% v. 6.8\%), and rubbing (1.1 times per day v. 0.1 times), while the Santa Gertrudis spent more time walking (12.1\% v. 6.6\%). They spent about the same time ruminating-lying (23.0\%), standing-idle (7.5\%), lying-idle (10.1\%), nursing (1 .6\%), watering (1.2 times), salting (0.3 times), defecating (6.5 times), and urinating (6.2 times). At the same time as the activities were being observed, the location within a pasture of the cow while grazing was noted. Utilization checks of perennial grasses in various zones (half-mile intervals from water) within a pasture were taken at periodic intervals. These data indicate that there was essentially no difference in the grazing distribution patterns in these pastures in each of which it was 3{\textonehalf} miles from water to the opposite side of the pasture.}, keywords = {arid range, cattle, hereford, Santa Gertrudis, southwestern United States}, url = {/files/bibliography/093.pdf}, author = {C.H. Herbel and Nelson, A.B.} } @proceedings {52522, title = {Procedures for field evaluation of drought tolerance}, year = {1958}, month = {1958}, keywords = {drought tolerance, field evaluation, procedures}, author = {C.H. Herbel} } @mastersthesis {52530, title = {Phenotypic and genetic relationships between type and weight of range cattle at different periods}, year = {1954}, note = {//??//NONE//}, month = {1954}, pages = {27}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle,breeding, cattle,genetics, cattle,productivity, dissertation, dissertations, genetics,cattle, theses, thesis}, author = {Romo, Anthony} } @article {52548, title = {Perennial grass composition as an indicator of condition of Southwestern mixed grass ranges}, journal = {Ecology}, volume = {29}, number = {2}, year = {1948}, month = {April 1948}, pages = {190-204}, abstract = {Events usually record their own history. Main results stand forth boldly but the signs that foreshadow them often are unnoticed. So it is with the marks left by good and poor range management. Realizing the range can tell its own story best, range managers have come to rely on indicators that may be observed on the ground and which reflect the condition of the range (Talbot, {\textquoteright}37). Among the commonly noted indicators of the condition of the range is density of forage plant cover, whether unpalatable and noxious plants occur in normal or abnormal abundance, and the absence or presence of accelerated soil erosion. Usually these indicators are evidence of a condition already existing. In the Southwest, often they fail to indicate early stages of range recovery or to forewarn of impending range deterioration. For example, unpalatable, deep-rooted shrubs are less important in indicator value than perennial grasses because they may move in slowly on overused ranges and often persist even though the grass cover has improved under good range management. Investigations conducted on the Santa Rita Experimental Rangeshow that the native grasses exhibit marked individuality in their response to various intensities of grazing and, thereby, indicate the early stages of trend either toward range recovery or toward range deterioration. This phenomenon is possible because the perennial grasses bear the brunt of grazing and, therefore, shows an earlier response than do lightly grazed or nongrazed associated plants. The present condition of grazing lands indicates there is a serious need for additional guides or criteria on which needed changes in range management can be made. The purpose of this article is twofold: (1) To present data regarding the floristic composition of perennial grass population as indicators of range recovery and range deterioration on mixed grass ranges of southern Arizona. (2) To portray the characteristic perennial grass patterns resulting from different grazing treatments on two specific range types on the Santa Rita Experimental Range in order to aid in the recognition of similar relationships on comparable ranges.}, keywords = {density of forage plant cover, indicator, perennial grass composition, range condition}, url = {/files/bibliography/070.pdf}, author = {Canfield, R.H.} } @article {52567, title = {Progress in utilization standards for western ranges}, journal = {Journal of the Washington Academy of Sciences}, volume = {33}, number = {6}, year = {1943}, month = {June 15, 1943}, pages = {161-169}, abstract = {Range utilization is essential to the welfare of the West and of the United States as a whole. The western range territory provides one-third of the cattle and calves, two-thirds of the sheep, and three-fourths of the wool and mohair grown in the United States. These livestock products are important even in ordinary times. They are indispensable during war. Because of the huge armed force, millions of war workers at strenuous toil, and lend-lease aid to the Allies, the country each year is using double its domestic wool production, and civilian meat consumption has been cut by more than one-third in order to balance consumption with supply.}, keywords = {livestock products, range utilization, wartime}, url = {/files/bibliography/061.pdf}, author = {R.S. Campbell} } @article {52606, title = {Poisonous drymaria on ranges of southern New Mexico}, journal = {Western Livestock}, volume = {21}, year = {1936}, month = {1936}, pages = {1, 4}, keywords = {drymaria, poisonous, southern New Mexico}, author = {E. L. Little Jr.} } @article {52613, title = {Partial phyllody of Yucca elata}, journal = {The Botanical Gazette}, volume = {94}, number = {(3)}, year = {1933}, month = {March 1, 1933}, pages = {619-620}, abstract = {

Observations on phyllody in Yucca elata, previously reported from the Jornada Experimental Range in southern New Mexico, dealt with specimens in which differentiation of flowers failed completely. All of the cases found from 1926 to 1931 were of this type. In July 1993, however, three specimens of partial phyllody were noticed. These specimens of partial phyllody, two of which are shown in figure 1, were produced in 1931, probably during the early summer. When they were found a year later, the panicles were dry, the capsules open and most of the seeds were dispersed. Even though the stalks were a year old, they were sufficiently well preserved to demonstrate this unusual feature for Y. elata.

}, keywords = {cause of condition, phyllody, Yucca elata}, url = {/files/bibliography/022.pdf}, author = {R.S. Campbell and Keller, J.G.} } @article {52619, title = {Plant succession and grazing capacity on clay soils in southern New Mexico}, journal = {Journal of Agricultural Research}, volume = {43}, number = {12}, year = {1931}, month = {December 15, 193}, pages = {1027-1051}, abstract = {

It is common knowledge that continued overgrazing, such as is prevalent on the semidesert ranges of the Southwest, reduces the stand of desirable forage plants and leads to serious range depletion, especially during periods of drought. Such depletion allows erosion of the valuable topsoil layer and permits rainfall to run off in torrential floods, with consequent damage to agricutlural lands and urban property in the valleys. Native vegetation, therefore, plays an improtant role not only in range conservation and improvement, but also in the protection of watersheds.

}, keywords = {clay soils, grazing capacity, plant succession, southern New Mexico}, url = {/files/bibliography/020.pdf}, author = {R.S. Campbell} } @article {52626, title = {The poisoning of livestock by Drymaria pachyphylla}, year = {1929}, note = {//??//NONE//}, month = {1929}, institution = {New Mexico Agricultural Experiment Station}, keywords = {book, books, cattle,toxic plants, chapter, chapters, Drymaria,toxicity, plant,Drymaria, report, reports, toxicity,Drymaria}, isbn = {Bulletin 173}, author = {Lantow, J. L.} } @article {52648, title = {Preliminary Report on Flora of New Mexico}, volume = {19}, year = {1913}, month = {June 24, 1913}, publisher = {U.S. Department of Agriculture}, keywords = {flora, New Mexico}, author = {Wooton, E.O. and Standley, P. C.} } @article {JRN55001, title = {Past and Present Research on the Jornada Experimental Range and Future Needs}, year = {1912}, type = {Historical Document }, abstract = {

The Jornada Range was set aside for experimental purposes by presidential proclamation in 1912. From 1912 to 1915 it was controlled by the Bureau of Plant Industry. From 1915 to 1953 it was under the jurisdiction of the Forest Service. In 1953 all range seeding research for domestic livestock and grazing management on rangelands not integrated in use with national forest ranges was transferred to the Agricultural Research Service. So, since 1953, the Jornada has been operated by the Arid Pasture and Range Section, Crops Research Division of the ARS.

}, url = {files/bibliography/Herbel-01.pdf}, author = {C.H. Herbel} }