@conference {JRN55402, title = {Vegetation dynamics in drylands related to the Pacific Decadal Oscillation in the 20th century}, booktitle = {Ecological Society of America annual conference}, year = {2022}, month = {3/1/2022}, abstract = {Background/questions/methods: Ecosystem transitions resulting from climatic drivers are observed at multiple time scales. In the arid southwest United States, the role of climate variation in the collapse and recovery of grassland communities is poorly understood. Here we use a quality-controlled vegetation monitoring dataset initiated in 1915 to ask what climate components were most closely correlated to perennial grass dynamics in the 20th century. We constructed a suite of models relating grass cover to climate variables known to influence dryland ecosystem behavior at multiple time scales, including annual precipitation, annual drought indices, El Nino Southern Oscillation (ENSO) index, and Pacific Decadal Oscillation (PDO) index. Results/conclusions: We found that dynamics of perennial grass collapse and recovery during the 20th century were most closely correlated to the Pacific Decadal Oscillation (PDO) index. The relationship out-performed models correlating grasses to yearly precipitation and drought indices, suggesting that ecosystem transitions attributed only to local disturbances were instead influenced by climate teleconnections. We also found that an incidence of grass recovery in the 1960s-70s was accompanied by a significant shift from core species (common, abundant species) to transient species (species that are patchy in space or time). Finally, the relationship between PDO and vegetation cover broke down after 1995, indicating that warming or land degradation overwhelmed multi-decadal variation driven by PDO.}, author = {Erica M. Christensen and D. K. James and Robb Randall and Brandon T Bestelmeyer} } @conference {JRN55405, title = {Vegetation dynamics in drylands related to the Pacific Decadal Oscillation in the 20th century}, booktitle = {Ecological Society of America (ESA)}, year = {2022}, month = {03/01/2022}, abstract = {Background/questions/methods: Ecosystem transitions resulting from climatic drivers are observed at multiple time scales. In the arid southwest United States, the role of climate variation in the collapse and recovery of grassland communities is poorly understood. Here we use a quality-controlled vegetation monitoring dataset initiated in 1915 to ask what climate components were most closely correlated to perennial grass dynamics in the 20th century. We constructed a suite of models relating grass cover to climate variables known to influence dryland ecosystem behavior at multiple time scales, including annual precipitation, annual drought indices, El Nino Southern Oscillation (ENSO) index, and Pacific Decadal Oscillation (PDO) index. Results/conclusions: We found that dynamics of perennial grass collapse and recovery during the 20th century were most closely correlated to the Pacific Decadal Oscillation (PDO) index. The relationship out-performed models correlating grasses to yearly precipitation and drought indices, suggesting that ecosystem transitions attributed only to local disturbances were instead influenced by climate teleconnections. We also found that an incidence of grass recovery in the 1960s-70s was accompanied by a significant shift from core species (common, abundant species) to transient species (species that are patchy in space or time). Finally, the relationship between PDO and vegetation cover broke down after 1995, indicating that warming or land degradation overwhelmed multi-decadal variation driven by PDO.}, author = {Erica M. Christensen and D. K. James and Rob Randall and Brandon T Bestelmeyer} } @conference {JRN55423, title = {Virtual fencing of nursing cattle grazing large pastures of Chihuahuan Desert rangelands}, booktitle = {Society for Range Management}, year = {2022}, abstract = {Virtual fencing (VF) is an emerging technology to control livestock dispersal. This technology includes collars that employ auditory-electric pulse cues to deter animals from trespassing into excluded zones. Our objective was to investigate VF application on extensive rangelands. VF-trained nursing Brangus cows were grazed in a 480 ha pasture at the New Mexico State University{\textquoteright}s Chihuahuan Desert Rangeland Research Center with the VF deactivated (control) or activated using three different polygon configurations. The VF-activated polygons excluded cattle from grazing either the East (209ha), West (200ha), or preferred Vegetation PV (80ha) within the pasture. Each pasture deployment lasted a week and the process was repeated on two groups of 11 and 18 cows, respectively. We analyzed 1) foraging behavior differences (control vs. VF-activated); 2) percentage of daily GPS locations within the excluded zones (control vs. VF-activated); and 3) number of auditory-electric pulses emitted during each VF-activated configuration (Excluded blocks East, West, or PV). The data were analyzed via an ANOVA to compare daily-derived variables. Cattle covered larger areas during control vs. VF-activated deployments (134.2 vs. 86.9ha P=0.04) with no differences in distance traveled nor cumulative activity index derived from the in-built motion sensors. When compared to the control, all VF-activated configurations significantly reduced the percentage of GPS positions within the excluded zone (East 52.27 vs. 0.67\%GPS P0<.01; West 18.49 vs. 0.49\%GPS P<0.01; PV 19.90 vs. 3.04\%GPS P<0.01; control vs. VF-activated respectively). Significantly (P<0.01) higher audio and electric pulses (2.09, 0.51 respectively) were emitted during the PV trials compared to East (1.12, 0.17) or West (1.12, 0.14) blocks. In conclusion, VF holds promise in controlling spatial exploration patterns of cattle in extensive rangelands. Polygon configuration requires further research to understand trade-offs between animal welfare and effective management.}, keywords = {cattle grazing, Chihuahuan Desert, large pastures, nursing, rangelands, virtual fencing}, author = {Nyamuryekung{\textquoteright}e, Shelemia and Andrew Cox and Perea, A. and Matthew M. McIntosh and Richard E. Estell and Andr{\'e}s F. Cibils and Holland, J. and Tony Waterhouse and G. Duff and M. Funk and Skye Aney and S. Spiegal and Brandon T Bestelmeyer and S. A. Utsumi} } @article {JRN55281, title = {Vector Surveillance, Host Species Richness, and Demographic Factors as West Nile Disease Risk Indicators}, journal = {Viruses}, volume = {13}, year = {2021}, month = {5/1/2021}, pages = {1-18}, abstract = {West Nile virus (WNV) is the most common arthropod-borne virus (arbovirus) in the United States (US) and is the leading cause of viral encephalitis in the country. The virus has affected tens of thousands of US persons total since its 1999 North America introduction, with thousands of new infections reported annually. Approximately 1\% of humans infected with WNV acquire neuroinvasive West Nile Disease (WND) with severe encephalitis and risk of death. Research describing WNV ecology is needed to improve public health surveillance, monitoring, and risk assessment. We applied Bayesian joint-spatiotemporal modeling to assess the association of vector surveillance data, host species richness, and a variety of other environmental and socioeconomic disease risk factors with neuroinvasive WND throughout the conterminous US. Our research revealed that an aging human population was the strongest disease indicator, but climatic and vector-host biotic interactions were also significant in determining risk of neuroinvasive WND. Our analysis also identified a geographic region of disproportionately high neuroinvasive WND disease risk that parallels the Continental Divide, and extends southward from the US{\textendash}Canada border in the states of Montana, North Dakota, and Wisconsin to the US{\textendash}Mexico border in western Texas. Our results aid in unraveling complex WNV ecology and can be applied to prioritize disease surveillance locations and risk assessment.}, keywords = {West Nile; mosquito; vector; spatiotemporal; neuroinvasive disease; Bayesian}, doi = {10.3390/v13050934}, url = {files/bibliography/21-015.pdf}, author = {John Humphreys and Katherine I. Young and Lee W Cohnstaedt and Kathryn A. Hanley and Debra C. Peters} } @article {JRN55272, title = {Vegetation Canopy Gap Size and Height: Critical Indicators for Wind Erosion Monitoring and Management}, journal = {Rangeland Ecology \& Management}, volume = {76}, year = {2021}, month = {May 2021}, pages = {78-83}, abstract = {Indicators of vegetation cover and structure are widely available for monitoring and managing rangeland wind erosion. Identifying which indicators are most appropriate for managers could improve wind erosion mitigation and restoration efforts. Vegetation cover directly protects the soil surface from erosive winds and reduces wind erosivity by extracting momentum from the air. The portion of the soil surface that is directly protected by vegetation is adequately described by fractional ground cover indicators. However, the aerodynamic sheltering effects of vegetation, which are more important for wind erosion than for water erosion, are not captured by these indicators. As wind erosion is a lateral process, the vertical structure and spatial distribution of vegetation are most important for controlling where, when, and how much wind erosion occurs on rangelands. These controlling factors can be described by indicators of the vegetation canopy gap size distribution and vegetation height, for which data are collected widely in the United States by standardized rangeland monitoring and assessment programs. In this paper we address why canopy gap size distribution and vegetation height are critical indicators of rangeland wind erosion and health. We review wind erosion processes to explain the physical role of these vegetation attributes. We then address the management implications including availability of data on the indicators on rangelands and needs to make the indicators and model estimates of wind erosion more accessible to the range management community.}, keywords = {canopy, dust monitoring, gap size, rangeland health, Vegetation height, wind erosion}, doi = {doi.org/10.1016/j.rama.2021.02.003}, url = {files/bibliography/21-007.pdf}, author = {Nicholas Webb and Sarah McCord and Brandon Edwards and Jeffrey E. Herrick and Emily Kachergis and Gregory S. Okin and Justin Van Zee} } @conference {JRN54997, title = {Variation of Seed Banks among Ecological States in the Chihuahuan Desert: Implications for Restoration}, booktitle = {72nd Society for Range Management International Meeting}, year = {2019}, month = {02/2019}, publisher = {Society for Range Management Meeting Abstracts}, organization = {Society for Range Management Meeting Abstracts}, address = {Minneapolis, Minnesota}, abstract = {

State transitions involving the encroachment of shrubs and loss of herbaceous species are known to be highly persistent in the Chihuahuan Desert, even when disturbances are reduced and shrubs are removed. The existing seedbank in these soils is poorly documented and seed bank limitation might constrain the recovery of historical herbaceous communities. From 2015 to 2017 we conducted a germinable seed bank study by collecting a total of 258 soil samples (each measuring 796 cm3) from randomly selected sites on 190,000 acres of the Jornada Experimental Range in Southern New Mexico. Sites were stratified by ecological states within each of the 10 ecological sites found on the range. Over a two-year period, these samples were provided ample water and monitored in greenhouse conditions. The soil yielded 12,777 seedlings from 159 species of vascular plants. Variance partitioning and redundancy analysis showed that ecological site and state explains significantly more variability in germinable seeds by species than spatial structure alone (15.17\% and 5.94\%, respectively; p=0.001); however, a considerable amount of unexplained variability exists. Seed banks in degraded states within ecological sites were generally limited with respect to desirable (native perennial) species with the exception of mesa dropseed grass (Sporobolus flexuosus) which occurred in 61.24\% of the sites and 39.54\% of the seedlings identified. Additionally, mesa dropseed is more widely dispersed than other desirable grass species within ecological sites. Our results suggest that seed bank limitation may contribute to the persistent absence of key herbaceous species. The prevalence of mesa dropseed in the seed bank {\textendash} even where it is not abundant aboveground {\textendash} suggests that establishment limitations including soil surface degradation and herbivory need to be overcome to trigger mesa dropseed increase, but that seeding may not be necessary.

}, author = {Kirsten B. Romig and D. K. James and Brandon T Bestelmeyer and Connie J. Maxwell and Joel R. Brown and S. W. Salley} } @conference {JRN55064, title = {Vulnerability of acequia communities to climate change}, booktitle = {Universities Council on Water Resources}, year = {2019}, month = {06/2019}, address = {Snowbird, UT}, abstract = {

Vulnerability to climate change can be conceptualized either as an outcome resulting from biophysical changes to a system, or as a condition that already exists in a system and is subject to complex interactions between biophysical and human factors. Much of the research on agricultural systems in the U.S. has used the outcome vulnerability framework and focuses on producing technical, infrastructural, or policy-level solutions to climate change impacts. These types of assessment do not necessarily consider a community{\textquoteright}s ability to apply these solutions. The alternative framework often applies the terms {\textquotedblleft}contextual{\textquotedblright} or {\textquotedblleft}starting point{\textquotedblright} vulnerability. Assessments using a contextual vulnerability framework incorporate biophysical, social, cultural, political, institutional and economic factors to define pre-existing vulnerabilities. Contextual vulnerability frameworks are well-suited for place-based research that seeks to formulate community-level responses to climate change impacts, especially where there are strong institutional factors to consider. In this paper, we first summarize the biophysical factors that acequia communities in Northern New Mexico will be exposed to under a changing climate, notably impacts on snowpack, water supply and the health of surrounding forests. We then review contextual vulnerabilities using a framework that draws on the five capitals model. Some of the key factors that reduce the vulnerability of acequia communities to climate impacts include the institutions associated with their community-based irrigation systems, and the social capital and {\textquotedblleft}reciprocal interdependence{\textquotedblright} that acequia membership generates. Contemporary factors that increase acequia vulnerability include land use change, property-rights fragmentation and population decline.

}, author = {Caitriana Steele and J.T. Reyes and Emile H. Elias} } @conference {JRN54942, title = {Vegetation effects on spatiotemporal variability in Aeolian mass flux over a range of ecological conditions}, booktitle = {International Conference on Aeolian Research}, year = {2018}, month = {06/2018}, address = {Bordeaux, France}, abstract = {

Issues of scale have long been a chief concern in efforts by the aeolian research community to monitor and model aeolian mass flux over spatially large areas. Observations over small sampling scales (\< 1 m2 ) dominate physical descriptions of aeolian transport processes and predictive mass flux equations. Consequently, those descriptions are unlikely to represent the controls of transport over space (\>\> 1 m2 ). Loss of process fidelity is compounded as area increases because additional sources of variance are introduced and unknown synergies occur between controlling factors (Figure 1). Uncertainty is further amplified by increasing landscape heterogeneity, but because monitoring efforts are often limited in scope, few data are available to adequately describe spatial variability of transport to produce unbiased areal estimates, particularly in vegetated landscapes. In this paper, we use transport and vegetation data from US National Wind Erosion Research Network (http://winderosionnetwork.org) sites to investigate spatiotemporal variability of transport and its controls for a range of vegetation conditions. For a given site, vegetation characteristics (e.g., canopy height, vegetative cover fraction, and gap size distribution) are recorded seasonally using standardized methods. Transport is measured using a stratified scheme of 27 MWAC collectors randomly located in groups of 3 within 9 cells in a 100 m2 plot. We use regression co-kriging to map monthly transport and investigate how vegetation as a controlling factor drives variability in transport. Results are expected to inform future modeling efforts and improve analyses of wind erosion and dust emission responses to land use and land cover change.

}, author = {Brandon Edwards and Nicholas Webb and Justin Van Zee and A. Chappell} } @article {JRN54928, title = {Vulnerability of field crops to midcentury temperature changes and yield effects in the Southwestern USA}, journal = {Journal of Climate Change}, volume = {148}, year = {2018}, month = {06/2018}, pages = {403-417}, chapter = {403}, abstract = {

Increased temperatures in the Southwestern USA will impact future crop production via multiple pathways. We used four methods to provide an illustrative analysis of midcentury temperature impacts to eight field crops. By midcentury, cropland area thermally suitable for maize cultivation is projected to decrease, while area suitable for cotton cultivation expands northward and nearly doubles in extent. The increase in area exposed to daily temperatures \>\ 35\ {\textdegree}C was highest for oat and maize. Estimates of yield reduction from heat stress for both maize and cotton indicate that historically, SW heat stress reduced cotton yield by 26\% and maize yield by 18\% compared to potential yield. By midcentury, we predict yield reduction from heat stress will reduce cotton and maize yields by 37 and 27\%, respectively, compared to potential yield. Our results contradict the notion that the warmest counties cultivating field crops will be the most impacted. Rather, future temperature, total crop area and crop sensitivity contribute to more complex county-level impacts. Identification of representative target environments under future temperature regimes can inform development of farm-based networks to evaluate new crop germplasm with increased heat tolerance and viable adaptation and management strategies to respond effectively to future temperatures.

}, doi = {doi.org/10.1007/s10584-017-2108-8}, url = {files/bibliography/18-025.pdf}, author = {Emile H. Elias and Marklein, Alison and John T Abatzoglou and Jake Dialesandro and Joel R. Brown and Caitriana Steele and A. Rango and Kerri Steenwerth} } @article {JRN54930, title = {Vulnerabilities of Southwestern U.S. rangeland-based animal agriculture to climate change}, journal = {Climatic Change}, volume = {148}, year = {2018}, month = {06/2018}, pages = {371-386}, chapter = {371}, abstract = {

The Southwestern US is a five-state region that has supported animal agriculture since the late 16th Century when European settlers crossed the Rio Grande into present day west Texas and southern New Mexico with herds of cattle, sheep, goats and horses. For the past 400\ years the rangeland livestock industry, in its many forms and manifestations, has developed management strategies and conservation practices that impart resilience to the climatic extremes, especially prolonged droughts, that are common and extensive across this region. Livestock production from rangelands in the southwest (SW) is adapted to low rainfall and high ambient temperatures, but will have to continue to adapt management strategies, such as reduced stocking rates, proper grazing management practices, employing animal genetics suited to arid environments with less herbaceous production, erosion control conservation practices, and alternative forage supplies, in an increasingly arid and variable climatic environment. Even though the aging demographics of western ranchers could be a deterrent to implementing various adaptations, there are examples of creative management coalitions to cope with climatic change that are emerging in the SW that can serve as instructive examples. More importantly, there are additional opportunities for incorporation of transformative practices and technologies that can sustain animal agriculture in the SW in a warmer environment. Animal agriculture in the SW is inherently resilient, and has the capacity to adapt and transform as needed to the climatic changes that are now occurring and will continue to occur across this region. However, producers and land managers will need to thoroughly understand the vulnerabilities and sensitivities that face them as well as the ecological characteristics of their specific landscapes in order to cope with the emerging climatic changes across the SW region.

}, doi = {doi.org/10.1007/s10584-016-1834-7}, url = {files/bibliography/18-008.pdf}, author = {Kris Havstad and Joel R. Brown and Richard E. Estell and Emile H. Elias and A. Rango and Caitriana Steele} } @article {JRN54792, title = {Vulnerability of California specialty crops to projected mid-century temperature changes}, journal = {Climatic Change}, volume = {148}, year = {2018}, month = {06/2018}, pages = {419-436}, chapter = {419}, abstract = {

Increasing global temperatures are likely to have major impacts on agriculture, but the effects will vary by crop and location. This paper describes the temperature sensitivity and exposure of selected specialty crops in California. We used literature synthesis to create several sensitivity indices (from 1 to 4) to changes in winter minimum and summer maximum temperature for the top 14 specialty crops. To estimate exposure, we used seasonal period change analysis of mid-century minimum and maximum temperature changes downscaled to county level from CMIP5 models. We described crop vulnerability on a county basis as (crop sensitivity index {\texttimes} county climate exposure {\texttimes} area of crop in county); individual crop vulnerabilities were combined to create an aggregate index of specialty crop vulnerability by county. We also conducted analyses scaled by crop value rather than area, and normalized to total specialty crop area in each county. Our analyses yielded a spatial assessment highlighting seasons and counties of highest vulnerability. Winter and summer vulnerability are correlated, but not highly so. High-producing counties (e.g., Fresno County in the San Joaquin Valley) are the most vulnerable in absolute terms, while northern Sacramento Valley counties are the most vulnerable in relative terms, due to their reliance on heat-sensitive perennial crops. Our results illustrate the importance of examining crop vulnerability from different angles. More physi- ological and economic research is needed to build a comprehensive picture of specialty crop vulnerability to climate change.

}, doi = {10.1007/s10584-017-2011-3}, url = {files/bibliography/18-023.pdf}, author = {Kerr, Amber and Jake Dialesandro and Kerri Steenwerth and Lopez-Brody, Nathan and Emile H. Elias} } @article {JRN54902, title = {Vegetation and terrain drivers of infiltration depth along a semiarid hillslope}, journal = {Science of the Total Environment}, volume = {644}, year = {2018}, pages = {1399-1408}, abstract = {

An improved understanding of the drivers controlling infiltration patterns in semiarid regions is of key importance, as they have important implications for ecosystem productivity, retention of resources and the restoration of degraded areas. The infiltration depth variability (ΔInf) in vegetation patches at the hillslope scale can be driven by different factors along the hillslope. Here we investigate the effects of vegetation and terrain attributes under hypothesis that these attributes exert a major control in\ ΔInf within the patches.We characterise the\ ΔInf within vegetation patches at a semiarid hillslope located at the Jornada Experimental Range at dry antecedent conditions preceding two winter frontal rainfall events.We measured these events that are typical during winter conditions, and are characterised by low intensity (0.67 and 4.48mm h-1) and a total rainfall of 10.4 and 4.6mm. High precision geo-referenced wetting front depth measurements were taken at various locations within the vegetation patches using differential GPS. Vegetation and terrain attributes were analysed to explain the\ ΔInf among the vegetation patches. The infiltration depths in the periphery of the patches were in general considerably deeper than those in the centre. The observations suggest that the upslope margin of the patches received additional water in the form of runon from upslope adjacent bare soil. Patch orientation with regard to the slope dictated the effect of the rest of the patch attributes and the distance to the hillslope crest on ΔInf. We found that primarily patch orientation, followed by shape and size modulate lateral surface water transport through their effects on overland flow paths and water retention; something that would be obscured under more simplistic characterisations based on bare versus uniform vegetated soil discrimination. {\textcopyright} 2018 Elsevier B.V. All rights reserved.

}, keywords = {hydrology, infiltration, patch dynamics, patch orientation, patch shape, patch size, vegetation patch}, doi = {10.1016/j.scitotenv.2018.07.052}, url = {files/bibliography/JRN54902.pdf}, author = {M. J. Rossi and Jorge Ares and Esteban Jobb{\'a}gy and Enrique Vivoni and Vervoort, R. W. and A. P. Schreiner-McGraw and Patricia M. Saco} } @conference {JRN54933, title = {Varying Geospatial Analyses to Assess Climate Risk and Adaptive Capacity in a Hotter, Drier Southwestern United States}, booktitle = {American Geophysical Union}, year = {2017}, month = {12/2017}, address = {New Orleans, Louisiana}, abstract = {

Assessing vulnerability of agricultural systems to climate variability and change is vital in securing food systems and sustaining rural livelihoods. Farmers, ranchers, and forest landowners rely on science-based, decision-relevant, and localized information to maintain production, ecological viability, and economic returns.
This contribution synthesizes a collection of research on the future of agricultural production in the American Southwest (SW). Research was based on a variety of geospatial methodologies and datasets to assess the vulnerability of rangelands and livestock, field crops, specialty crops, and forests in the SW to climate-risk and change. This collection emerged from the development of regional vulnerability assessments for agricultural climate-risk by the U.S. Department of Agriculture (USDA) Climate Hub Network, established to deliver science-based information and technologies to enable climate-informed decision-making.
Authors defined vulnerability differently based on their agricultural system of interest, although each primarily focuses on biophysical systems. We found that an inconsistent framework for vulnerability and climate risk was necessary to adequately capture the diversity, variability, and heterogeneity of SW landscapes, peoples, and agriculture. \ Through the diversity of research questions and methodologies, this collection of articles provides valuable information on various aspects of SW vulnerability. All articles relied on geographic information systems technology, with highly variable levels of complexity. Agricultural articles used National Agricultural Statistics Service data, either as tabular county level summaries or through the CropScape cropland raster datasets. Most relied on modeled historic and future climate information, but with differing assumptions regarding spatial resolution and temporal framework. We assert that it is essential to evaluate climate risk using a variety of complementary methodologies and perspectives. In addition, we found that spatial analysis supports informed adaptation, within and outside the SW United States. The persistence and adaptive capacity of agriculture in the water-limited Southwest serves as an instructive example and may offer solutions to reduce future climate risk.

}, author = {Emile H. Elias and J.T. Reyes and Caitriana Steele and A. Rango} } @article {JRN54804, title = {Vegetation in drylands: Effects on wind flow and aeolian sediment transport}, journal = {Land}, volume = {6, 64}, year = {2017}, month = {09/2017}, abstract = {

Drylands are characterised by patchy vegetation, erodible surfaces and erosive aeolian processes. Empirical and modelling studies have shown that vegetation elements provide drag on the overlying airflow, thus affecting wind velocity profiles and altering erosive dynamics on desert surfaces. However, these dynamics are significantly complicated by a variety of factors, including turbulence, and vegetation porosity and pliability effects. This has resulted in some uncertainty about the effect of vegetation on sediment transport in drylands. Here, we review recent progress in our understanding of the effects of dryland vegetation on wind flow and aeolian sediment transport processes. In particular, wind transport models have played a key role in simplifying aeolian processes in partly vegetated landscapes, but they remain challenging in some respects. We identify potential future avenues for research that would help to elucidate the roles of vegetation distribution, geometry and scale in shaping the entrainment, transport and redistribution of wind-blown material at multiple scales. Gaps in our collective knowledge must be addressed through a combination of rigorous field, wind tunnel and modelling experiments.

}, doi = {doi:10.3390/land6030064}, url = {files/bibliography/17-022.pdf}, author = {Mayaud, Jerome and Nicholas Webb} } @conference {JRN54618, title = {Vegetation selection by Angus crossbred vs. Raramuri Criollo nursing cows grazing Chihuauan Desert rangeland in summer}, booktitle = {69th Annual Meeting of the Society for Range Managment}, year = {2016}, month = {12/2016}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Corpus Christi, TX}, abstract = {
We examined vegetation selection patterns of nursing Angus X Hereford crossbred (AH) and Raramuri Criollo (RC) cows grazing Chihuahuan Desert vegetation during the growing season. Eleven cows of each group grazed separately in two large pastures (1190ha, 1165ha) from mid-July until mid-August 2015 (28 days). GPS coordinates were recorded at 10 min intervals on five cows of each group. Vegetation in the pastures included honey mesquite (Prosopis glandulosa) intermixed with perennial grasses on sandy soils or tobosa (Pleuraphis mutica) and burrograss (Schleropogon brevifolius) in lower areas with clayey soils. GPS data were overlaid on a vegetation map of the pastures in ArcGIS. Mapped vegetation types were: bare ground, burrograss, mesquite, mesquite dunes, other shrubs, Sporobolus spp., and tobosa. Ivlev{\textquoteright}s electivity index (E) for each vegetation type was calculated for all collared cows (n=10). A t-test revealed statistical differences in E between groups for all seven vegetation types. Compared to AH cows, RC showed higher preference for bare ground areas presumably dominated by annuals (ERC = 0.34; EAH = -1.00; P\<0.01) and burrograss areas (ERC = 0.19; EAH = -0.25; P\<0.01), lower preference for mesquite (ERC = 0.03; EAH = 0.13; P = 0.02), mesquite dunes (ERC = -0.08; EAH = 0.02; P\<0.01), and tobosa grasslands (ERC = -0.11; EAH = 0.12; P\<0.01), and lower avoidance of other shrubs (ERC = -0.26; EAH = -0.70; P= 0.04) and Sporobolus areas (ERC = -0.42; EAH = -0.88; P\<0.01). Our preliminary results suggest that RC cows employ foraging strategies during the growing season that differ significantly from AH cows which are commonly used in our region. \ 
}, author = {S. Nyamuryekung{\textquoteright}e and Andr{\'e}s F. Cibils and Richard E. Estell and Amy L. Gonzalez} } @conference {JRN54401, title = {Vulnerabilities and adaptive capacities of selected southwestern crops to climate change}, booktitle = {Climate Prediction Applications Science Workshop (CPASW)}, year = {2015}, month = {03/2015}, address = {Las Cruces, NM}, abstract = {

By the middle of the 21st Century, maximum annual temperatures in the Southwest (SW) are expected to increase by 2-4 C with the highest increases occurring in the summer months of Jun-Aug. While annual precipitation may remain similar to 1971-2000 values, Mar-May precipitation in the SW may decline up to 20\% in certain locations. These projections, along with likely increases in extreme events such as heat waves and droughts, will impact crop production via multiple pathways including water scarcity, temperature sensitivity and cumulative ecosystem effects. We present examples of the likely consequences for specific annual and perennial crops common in the SW United States. The main field crops in the SW by area and production value are alfalfa, cotton, wheat, corn and rice. The optimum temperature range for maximum grain yield of these crops will be exceeded in broader spatial and temporal scales across much of the SW. The winter chilling requirements for stone fruit and tree nuts will not be met by the middle of the 21st century, resulting in lower yields. The observed "summer slump" in alfalfa, which is related to high temperatures in southern CA and AZ, will likely continue and expand. There are several adaptive measures that can be implemented to ensure yields. Ensuring adequate irrigation water supply is necessary. Certain crops, such as barley and safflower, are well adapted to arid environments and may represent a viable substitute for more water-intensive and vulnerable crops. Planting drought tolerant cultivars may help sustain yields. For certain crops, such as corn, wheat and stone-fruits, growth in regions representing optimal thermal ranges may be the best option for sustained production.

}, author = {Emile H. Elias and A. Rango and Caitriana Steele and Kris Havstad} } @conference {JRN54451, title = {Visualizing and quantifying microtopographic change of dryland landscapes from an unmanned aircraft system}, 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:\  Soil and site stability are key attributes of assessing the health of dryland landscapes because these lands are susceptible to high rates of wind- and water-caused erosion. Field techniques for measuring and monitoring soil erosion in drylands are often labor intensive and require many field visits. As a result, such field methods usually cover only small areas. There is a growing effort to monitor natural resources at broad scales that is driving the need for new tools to monitoring soil erosion and its effects on ecological functions and resource availability. One remote-sensing technique that could be used to measure soil movement from very-high resolution (VHR) aerial imagery is digital elevation model (DEM) differencing, where a DEM of the land surface is created using aerial photogrammetry methods at multiple points in time. By geographically co-registering DEMs created from VHR imagery obtained via unmanned aerial systems (UAS) and subtracting one elevation surface from the other, an estimate of soil elevation change can be defined. Such analysis allows quantification and visualization of soil erosion, deposition, and redistribution. We tested this technique to model the soil surface change of Chihuahuan Desert shrublands located near Las Cruces, NM, USA. We acquired 20 overlapping aerial images from a BAT 4 UAS for six 50 x 50m test plots in May 2014 and in February 2015. From the imagery, we created 5-cm spatial resolution DEMs of each of the plots and subtracted one image date from the other to create a difference image.\  Results/Conclusions: Accuracy of the soil surface DEMs was shown to be very good compared to ground-based elevation profiles generated from a laser range finder slid along an erosion bridge. 95\% of aerial DEM height measurements were within 5 cm of the heights measured from the erosion bridge. The average difference between ground-based and aerial methods was less than 2 cm. Minor soil surface changes occurred between the image dates due to vehicular traffic and erosion processes. These changes were captured with strong agreement between the ground-based and aerial methods. Our results demonstrate that we can effectively observe the topographical change (cm scale) of rangeland soils from UAS platforms and gives distinct efficiency advantages for characterizing soil surface movement over broad areas. This information, available at scales that are commensurate with ecological processes operating in the study area, will allow for easier and more accurate quantification of resource distribution and loss.\  IGN6-5.\  OPS 4-16.

}, author = {Jeffrey K. Gillan and Jason W. Karl} } @article {JRN53962, title = {Virtual herding for flexible livestock management - a review}, journal = {The Rangeland Journal}, volume = {36}, year = {2014}, month = {06/2014}, pages = {205-221}, chapter = {205}, abstract = {

Free-ranging livestock play a pivotal role globally in the conversion of plant tissue into products and services that support man\’s many and changing lifestyles. With domestication came the task of providing livestock with an adequate plane of nutrition while simultaneously managing vegetation for sustainable production. Attempting to meld these two seemingly opposing management goals continues to be a major focus of rangeland research.\  Demand for multiple goods and services from rangelands today requires that livestock production make the smallest possible \“negative hoofprint.\” Advancements in global navigation satellite system, geographic information system, and electronic/computing technologies, coupled with improved understanding of animal behavior, positions virtual fencing (VF) as an increasingly attractive option for managing free-ranging livestock.\  Virtual fencing offers an alternative to conventional fencing by replacing physical barriers with sensory cues to control an animal\’s forward movement. Currently, audio and electrical stimulation are the cues employed. When VF becomes a commercial reality, manual labor will be replaced in large part with cognitive labor for real-time prescription-based livestock distribution management that is robust, accurate, precise and flexible.\  The goal is to manage rangeland ecosystems optimally for soils, plants, herbivores in addition to the plant and animal\’s microflora. However, maximizing the benefits of VF will require a paradigm shift in management by using VF as a \“virtual herder\” rather than simply as a tool to manage livestock within static physical barriers.

}, keywords = {grazing systems, hoof-action, livestock management, paddocks, pastures, plant-animal interface, rumen dynamics, stocking rate}, doi = {10.1071/RJ13092}, url = {/files/bibliography/14-015.pdf}, author = {D.M. Anderson and Richard E. Estell and Jerry L. Holechek and S. Ivey and Geoffrey Smith} } @article {JRN53944, title = {Valuing and rewarding ecosystem services from rangelands}, journal = {Rangelands}, volume = {36}, year = {2014}, month = {04/2014}, pages = {12-19}, chapter = {12}, abstract = {

Rangeland ecosystems provide a wide variety of ecosystem services. Some are relatively well quantified and have highly structured markets, while others are poorly defined and lack even rudimentary market opportunities. The highly variable nature of rangelands require a systematic approach to quantifying ecosystem services and assuring both public and private sector markets that prescribe changes in management do indeed result in enhanced outputs of goods and services. We propose the use of Ecological Site Descriptions and State and Transition Models to link ecosystem services to changes in management as a basis for a more transparent markets.

}, keywords = {Ecological Site Description, ecosystem services, rangelands, stewardship}, doi = {10.2111/rangelands-d-13-00075.1}, url = {/files/bibliography/14-010.pdf}, author = {MacLeod, Neil and Joel R. Brown} } @conference {JRN55166, title = { Virtual Fencing-A Corrective or Substantive Paradigm}, booktitle = {4TH AUSTRALIAN AND NEW ZEALAND SPATIALLY ENABLED LIVESTOCK MANAGEMENT SYMPOSIUM }, year = {2013}, month = {9/26/2013}, abstract = {

Grazing and browsing animals play a pivotal role in converting plant tissue into edible as well as non-edible products and services that support man{\textquoteright}s continually changing life styles. With domestication came the task of providing animals an adequate plane of nutrition for growth and reproduction while simultaneously managing vegetation for sustainable production. Attempting to resolve these two seemingly opposing management goals has occupied much of range animal ecology research to date. Today{\textquoteright}s demands for multiple goods and services from rangelands places even more of a focus on bringing about optimum livestock production with the smallest "hoof print" possible. Virtual fencing (VF) is an evolving methodology of animal control that requires at least a rudimentary understanding of the atmospheric sciences, soil science, plant science, animal science, the global navigation satelite system (GNSS), geographic information systems (GIS), ethology and 21st century electronics. Melding these diverse disciplines together to produce a methodology for controlling free-ranging animals stands out as holding much promise for managing animal dominated landscapes. When VF becomes a commercial reality the use of manual labor to control livestock will largely be replaced with cognitive labor that will result in prescription based livestock management that is robust, accurate, precise and flexible. By managing the spatio-temporal aspects of foraging in real-time controlled utilization of vegetation will be possible with prescription like precision. The end result will be ecosystem management capable of providing optimum plant as well as realistic growing conditions for animals without detracting from the additional demands being placed on rangelands today for goods and services beyond just providing nutrition for free-ranging livestock and wildlife. The methodology of VF should not be viewed as simply a new tool to caITy on current management but rather it offers the possibility of providing the basis for a new paradigm shift in managing stocking density in real-time. This approach to livestock management can be thought of as "virtual shepherding" for the 21st century.

}, author = {D.M. Anderson} } @article {49840, title = {Vegetation index differencing for broad-scale assessment of productivity under prolonged drought and sequential high rainfall conditions}, journal = {Remote Sensing}, volume = {5}, year = {2013}, month = {01/2013}, pages = {327-341}, chapter = {327}, abstract = {

Spatially-explicit depictions of plant productivity over large areas are critical to monitoring landscapes in highly heterogeneous arid ecosystems. Applying radiometric change detection techniques we sought to determine whether: (1) differences between pre- and post-growing season spectral vegetation index values effectively identify areas of significant change in vegetation; and (2) areas of significant change coincide with altered ecological states. We differenced NDVI values, standardized difference values to Z-scores to identify areas of significant increase and decrease in NDVI, and examined the ecological states associated with these areas. The vegetation index differencing method and translation of growing season NDVI to Z-scores permit examination of change over large areas and can be applied by non-experts. This method identified areas with potential for vegetation/ecological state transition and serves to guide field reconnaissance efforts that may ultimately inform land management decisions for millions of acres of federal lands.\ 

}, keywords = {change detection; rangeland monitoring; Landsat; ecological state mapping; state-and-transition models; phenology}, doi = {10.3390/rs5010327 }, url = {/files/bibliography/13-001.pdf}, author = {Dawn M. Browning and Caitriana Steele} } @article {49995, title = {Vegetation maps at the passage of the Taylor Grazing Act (1934): A baseline to evaluate rangeland change after a regime shift}, journal = {Rangelands}, volume = {33}, year = {2011}, month = {02/2011}, pages = {13-19}, chapter = {13}, abstract = {Data from New Mexico range survey maps created shortly after the passage of the Taylor Grazing Act in 1934 have been preserved and are being used to document changes in vegetation. The range survey data were collected at the time of a critical shift in rangeland policy and practice in federal lands of the United States. This paper describes the historical context of the post-Taylor range surveying, documents the process of creating the 1930s vegetation cover data from the maps, and illustrates how the data are being used to understand patterns of ecosystem change}, keywords = {1934, landscape change, range-survey maps, rangeland change, rangeland management, regime shift, Taylor Grazing Act, vegetation maps}, doi = {10.2111/RANGELANDS-D-10-00031.1}, url = {/files/bibliography/11-016.pdf}, author = {R. K. Skaggs and Edwards, Zach and Brandon T Bestelmeyer and J. Wright and Jebediah C. Williamson and Phil Smith} } @article {50121, title = {Vegetation controls on small-scale runoff and erosion dynamics in a degrading dryland environment}, journal = {Hydrological Processes}, volume = {23}, year = {2009}, note = {//USDA//LTER V//entered 06/26/2009}, month = {2009}, pages = {1617-1630}, abstract = {

This paper investigates the controls of vegetation on runoff and erosion dynamics in the dryland environment of Jornada, New Mexico, USA. As the American southwest has seen significant shifts in the dominant vegetation species in the past 150 years, an understanding of the vegetation effects on hydrological and erosional processes is vital for understanding and managing environmental change. Small-scale rainfall simulations were carried out to identify the hydrological and erosional processes resulting from the grassland and shrubland vegetation species. Results obtained using tree-regression analysis suggested that the primary vegetation control on runoff and erosion is the shrub type and canopy density, which directly affects the local microtopographic gradient of mounds beneath the shrubs. Significant interactions and feedbacks were found to occur among the local mound gradient, crust cover, soil aggregate stability and antecedent soil moisture between the different vegetation species for both the runoff and erosion responses. Although some of the shrub species were found to produce higher sediment yields than the grass species, the distinguishing feature of the grassland was the significantly higher enrichment in the fine sediment fraction compared to all other surface cover types. This enrichment in fines has important implications for nutrient movement in such environments. Copyright {\textcopyright} 2009 John Wiley \& Sons, Ltd.

}, keywords = {article, drylands, erosion, hydrology, journal, rainfall simulation, runoff, tree regression, vegetation}, doi = {10.1002/hyp.7293}, url = {files/bibliography/JRN00531.pdf}, author = {Michaelides, Katerina and Lister, Debbie and John Wainwright and A.J. Parsons} } @conference {50166, title = {Variation in ecological resilience: a fundamental concept for rangeland ecology}, booktitle = {Society for Range Management}, series = {Building Bridges: Grasslands to Rangelands}, year = {2008}, month = {Janury 26-31, 20}, pages = {1480}, address = {Louisville, KY}, abstract = {The concepts and terminology associated with ecological resilience are fast becoming a common language for the study of global change. We review the application of the broad concept of resilience to rangeland ecology, connecting it to several well-established rangeland concepts including equilibrial/nonequilibrial rangeland systems, ecological sites, succession, and state-and-transition models. We argue that resilience concepts have the potential to provide a holistic framework for rangeland ecology that links advances across disciplines including pedology, plant ecology, landscape ecology, rural sociology, and economics, and we illustrate this linkage. In order to realize this potential, however, we will need to move beyond vague metaphors to produce real-world examples and then general strategies that practitioners and scientists find worthwhile to emulate.}, keywords = {ecological, rangeland ecology, resilience}, author = {Brandon T Bestelmeyer and D.D. Briske and Joel R. Brown and Kris Havstad and R. K. Skaggs} } @conference {50167, title = {Vulnerability and triggers in threshold development: models from the Chihuahuan Desert}, booktitle = {Society for Range Management}, year = {2008}, month = {January 26-31, 2}, pages = {1487}, address = {Louisville, KY}, abstract = {We review models developed for the Draw and Loamy ecological sites in Major Land Resource Area 42.2 in southwestern New Mexico and review empirical support obtained for parts of the model. We describe evidence for 1) vulnerability to transitions and associated triggers and 2) the characteristics of alternative states. Remote-sensing based evidence supports the notion that fragmentation of grass cover creates vulnerability to transition, and anecdotal evidence supports the notion that high intensity storms serve as triggers that initiate erosion and gully formation. Field measurements indicate that degradation of soil structure, increased run-off, and reduced water infiltration are important feedbacks components driving the transition and reinforcing state changes. These relationships are strongly mediated by soil horizon development differences within the ecological site. The state-and-transition model thus links these scientific studies and provides indicators that can be used by managers to gauge the likelihood of threshold development.}, keywords = {threshold development}, author = {Brandon T Bestelmeyer and Jeffrey E. Herrick and Caitriana Steele} } @conference {50181, title = {Vegetation canopy structure from NASA EOS multiangle imaging}, booktitle = {AGU 2008 Fall meeting}, series = {AGU 2008 Fall Meeting}, year = {2008}, month = {December 15-19, }, pages = {B33D-04}, address = {San Francisco, CA}, abstract = {We used red band bidirectional reflectance data from the NASA Multiangle Imaging SpectroRadiometer (MISR) and the MODerate resolution Imaging Spectroradiometer (MODIS) mapped onto a 250 m grid in a multiangle approach to obtain estimates of woody plant fractional cover and crown height through adjustment of the mean radius and mean crown aspect ratio parameters of an hybrid geometric-optical (GO) model. We used a technique to rapidly obtain MISR surface reflectance estimates at 275 m resolution through regression on 1 km MISR land surface estimates previously corrected for atmospheric attenuation using MISR aerosol estimates. MISR data were used to make end of dry season maps from 2000-2007 for parts of southern New Mexico, while MODIS data were used to replicate previous results obtained using MISR for June 2002 over large parts of New Mexico and Arizona. We also examined the applicability of this method in Alaskan tundra and forest by adjusting the GO model against MISR data for winter (March 2000) and summer (August 2008) scenes. We found that the GO model crown aspect ratio from MISR followed dominant shrub species distributions in the USDA, ARS Jornada Experimental Range, enabling differentiation of the more spherical crowns of creosotebush (Larrea tridentata) from the more prolate crowns of honey mesquite (Prosopis glandulosa). The measurement limits determined from 2000-2007 maps for a large part of southern New Mexico are ~0.1 in fractional shrub crown cover and ~3 m in mean canopy height (results obtained using data acquired shortly after precipitation events that radically darkened and altered the structure and angular response of the background). Typical standard deviations over the period for 12 sites covering a range of cover types are on the order of 0.05 in crown cover and 2 m in mean canopy height. We found that the GO model can be inverted to retrieve reasonable distributions of canopy parameters in southwestern environments using MODIS V005 red band surface reflectance estimates at ~250 m spatial resolution accumulated over 16 day periods. The MODIS (N=895) and MISR (N=576) estimates of forest height and cover both showed agreement with USDA, Forest Service estimates, with MODIS mean absolute errors (MAE) of 0.09 and 8.4 m respectively; and MISR MAE of 0.10 and 2.2 m, respectively, noting that a sub-optimal background was used for the MODIS inversions. The MODIS and MISR MAE for estimates of aboveground woody biomass via regression against Forest Service estimates were both 10.1 Mg.ha-1. We found that red band MISR data for central Alaska can be used to obtain first-order estimates of forest cover and height using a snow-free summer scene and shrub cover using a winter scene with full snow cover. The GO model inversion results are often physically unrealistic but spatial distributions correspond to high resolution images and reflect the potential for the multiangle/GO method to retrieve meaningful information that is qualitatively different to that obtained using vegetation indices.}, author = {M. Chopping and J. V. Martonchik and Michael Bull and A. Rango and C. Schaaf and F. Zhao and Want, Z.} } @article {50308, title = {Virtual Fencing - past, present and future}, journal = {The Rangeland Journal}, volume = {29}, year = {2007}, month = {June 15, 2007}, pages = {65-78}, publisher = {CSIRO Publishing}, abstract = {Virtual fencing is a method of controlling animals without ground based natural or man made structures. Control occurs by altering an animal\&$\#$39;s behavior through one or more sensory cues administered to the animal after it has attempted to penetrate an electronically generated 2-dimensional boundary. This boundary can be any geometrical shape, and though unseen by the eye, is detected by an electronic computer system worn by the animal. Autonomous programmable systems use an electronic signal, most commonly from the Global Positioning System (GPS) of satellites that emit electronic signals in the radio frequency (RF) range. Algorithms within a Geographic Information System (GIS) within the computer system worn by the animal use these data to determine if a cue should be applied and if so what cue(s), where on the body the cues should be applied and for how long. The first commercial virtual fencing system, patented in 1973 for controlling domestic dogs, was successfully used in 1987 to contain goats in the first experiment to control livestock using virtual fencing. Since then researchers using commercial as well as custom designed systems have successfully demonstrated that virtual fencing can successfully hold as well as move livestock over the landscape (proof-of-concept). Commercial virtual livestock control systems do not yet exist; however, research in Australia and the United States continues toward this goal. Pending research needs relating to this method of animal control are discussed in light of the currently available technologies.}, keywords = {animal tracking, biotelemetry systems, Directional Virtual Fencing, dog training collars, DVFTM, electronic fences, Global Positioning System, GPS}, url = {/files/bibliography/07-018.pdf}, author = {D.M. Anderson} } @article {50315, title = {Virtual Fencing Applications: Implementing and Testing an Automated Cattle Control System}, journal = {Computers and Electronics in Agriculture}, volume = {56}, year = {2007}, month = {April 2007}, pages = {14-22}, abstract = {Managing livestock movement in extensive systems has environmental and production benefits. Currently permanent wire fencing is used to control cattle; this is both expensive and inflexible. Cattle are known to respond to auditory and visual cues and we investigated whether these can be used to manipulate their behavior. Twenty-five Belmont Red steers with a mean live weight (LW) of 270 kg were each randomly assigned to one of five treatments. Treatments consisted of a combination of cues (audio, tactile and visual stimuli) and consequence (electrical stimulation). The treatments were electrical stimulation alone, audio plus electrical stimulation, vibration plus electrical stimulation, light plus electrical stimulation and electrified electric fence (6 kV) plus electrical stimulation (experimental control). Cue stimuli were administered for 3 seconds followed immediately by electrical stimulation (consequence) of 1 kV for 1 second. The experiment tested the operational efficacy of on-animal control or virtual fencing system. A collar-halter device was designed to carry the electronics, batteries and equipment providing the stimuli, including audio, vibration, light and electrical of a prototype virtual fencing device. Cattle were allowed to travel along a 40 m alley to a group of peers and feed while their rate of travel and response to the stimuli recorded. The prototype virtual fencing control system was successful in modifying the behavioural of the cattle. The rate of travel along the alley demonstrated the large variability in behavioural response associated with tactile, visual and audible cues. The experiment demonstrated virtual fencing has potential for controlling cattle in extensive grazing systems. However, larger numbers of cattle need to be tested to derive a better understanding of the behavioral variance. Further controlled experimental work is also necessary to quantify the interaction between cues, consequences and cattle learning.}, keywords = {animal behaviour, fencing, free-ranging cattle, prototype virtual fencing device, sensory stimuli, wireless sensor network}, url = {/files/bibliography/07-009.pdf}, author = {Bishop-Hurley, G.J. and Swain, D.L. and D.M. Anderson and Sikka, P. and Crossman, C. and Peter Corke} } @article {50329, title = {Volatile compounds on the leaf surface of intact and regrowth tarbush (Flourensia cernua DC) canopies}, journal = {Journal of Chemical Ecology}, volume = {33}, year = {2007}, month = {September 25, 20}, pages = {1867-1875}, abstract = {

Shrub expansion into desert grasslands is a serious problem resulting in loss of forage and rangeland productivity. Flourensia cernua DC (tarbush) is one such shrub contributing to the decline of Chihuahuan Desert grasslands. Our previous research has shown tarbush consumption by sheep and goats to be negatively related to leaf surface concentration of individual terpenes and epicuticular wax. Concentrations of compounds such as terpenes often change with plant age and phenology. Our objective was to examine the effect of altering the vegetative state of tarbush on volatile chemicals. Ninety tarbush plants were randomly selected and all biomass within 10 cm of the soil surface was removed from 45 plants during winter dormancy. Leaves were collected the following summer during active growth from the canopy of intact controls and resprouts. Leaf surface volatiles were analyzed by gas chromatography-mass spectroscopy and subjected to univariate analysis of variance and stepwise discriminate analysis. Of the 87 compounds present on tarbush leaves, 35 were greater in canopy samples and 16 were greater in regrowth samples based on univariate analysis (P\< 0.05). Mean concentration of total volatiles on canopy leaves tended to be less (P = 0.062) than that of regrowth (3642 vs. 4684 {\`\i}g/g DM). Nine compounds in the discriminant analysis ({\'a}-muurolene, iso-borneol, unknown$\#$6, p-cymen-8-ol, unknown$\#$7, sabinene, {\^a}-caryophyllene, {\"a}-cadinene, and {\'a}-copaene) explained 95\% of the variation between canopy and regrowth samples. Lower cumulative concentration of volatile compounds in canopy than regrowth samples suggests repsrouts may be less vulnerable to herbivory than intact tarbush.

}, keywords = {Flourensia cernua, plant secondary metabolites, regrowth, tarbush, terpenes}, doi = {10.1007/s10886-007-9360-8 }, url = {/files/bibliography/07-029.pdf}, author = {E.L. Fredrickson and Richard E. Estell and M.D. Remmenga} } @proceedings {50406, title = {Virtual Fencing - A Concept into Reality}, year = {2006}, month = {June 14-15, 2006}, pages = {61-91}, address = {Rockhampton, Queensland, Australia}, abstract = {Virtual fencing is a method of controlling animals without ground based, natural or man made structures. Control occurs by altering an animal{\textquoteright}s behavior through one or more sensory cues administered to the animal after it has attempted to penetrate an electronically generated 3-dimensional boundary. This boundary can be any geometrical shape, and though unseen by the eye, is detected by an electronic computer system worn by the animal. Autonomous programmable systems use an electronic signal, most commonly from the Global Positioning System (GPS) of satellites that emanate electronic signals in the radio frequency (RF) range. Algorithms within a Geographic Information System (GIS) use these data to determine if a cue should be applied and if so what cue(s), where on the body the cues should be applied and for how long. The first commercial virtual fencing system, patented in 1973 for controlling domestic dogs, was successfully used in 1987 to contain goats in the first experiment to control livestock using virtual fencing. Since then researchers using commercial as well as custom designed systems have successfully demonstrated proof-of-concept that virtual fencing can successfully hold as well as move livestock over the landscape. Commercial virtual livestock control systems do not yet exist; however, research in Australia and the United States continues toward this goal. Pending research needs relating to this method of animal control are discussed in light of currently available technologies.}, keywords = {controlling animals, virtual fencing}, url = {/files/bibliography/06-073Proc.pdf}, author = {D.M. Anderson} } @article {50471, title = {Volatile composition of Guiterrizia sarothrae (broom snakeweed) as determined by steam distillation and solid phase microextraction}, journal = {Journal of Essential Oil Research}, volume = {18}, year = {2006}, month = {April 1, 2006}, pages = {121-125}, abstract = {Guiterrizia sarothrae (broom snakeweed, snakeweed) is a prevalent species on rangelands throughout much of the western United States. This plant has been intensely studied in order to minimize its negative impact on forage production and livestock health. Although G. sarothrae has been used for centuries to remedy various ailments, scientific investigations of the plant\¿s medicinal value are difficult to find in the literature. The objective of this study was to explore the volatile chemical composition of G. sarothrae. Shoots from 88 actively growing plants showing no signs of root borer infestation were selected from five sites on the Chihuahuan Desert of southern New Mexico. Volatiles were extracted from ground, composite tissues by steam distillation and by solid phase microextraction (SPME), then separated and analyzed by gas chromatography with mass spectral and flame ionization detection. Comparing retention indices and mass spectra to known compounds identified ninety chemicals. Retention indices and 70 eV mass spectra are also provided for seven unknowns. Compounds detected varied in quantity between extraction protocols. In oil, cryptone (6.4\%) and beta-eudesmol (5.9\%) were the only compounds comprising more than 5\% of the chromatographic peak area. In samples prepared by solid-phase microextraction, limonene (10.4\%), beta-pinene (9.6\%), beta-eudesmol (8.0\%), sabinene (7.8\%), cryptone (6.5\%), alpha-pinene (5.5\%), and ortho-cymene (5.2\%) accounted for 53\% of the extracted volatiles. The results presented reveal a complex volatile composition from which unique compounds may still be identified.}, url = {/files/bibliography/06-013.pdf}, author = {M.E. Lucero and Morrison, A. and E.L. Fredrickson and Richard E. Estell and D. Richman} } @article {50528, title = {Virtual Fencing - Automated Animal Control in the 21st Century}, volume = {1}, year = {2005}, month = {June 2005}, pages = {13}, chapter = {13}, abstract = {Controlling free-ranging animal distribution is among the most challenging jobs a producer faces when managing livestock. Melding of time-tested animal husbandry practices with cutting-edge technological advances and scientific breakthroughs coming from the disciplines of range, animal and ethological sciences.}, keywords = {animal, automated, control, fencing, virtual}, url = {/files/bibliography/05-012.pdf}, author = {D.M. Anderson} } @article {50553, title = {Vegetation changes in the Jornada Basin from 1858 to 1998}, journal = {Journal of Arid Environments}, volume = {61}, number = {4}, year = {2005}, month = {June 1, 2005}, pages = {651-668}, abstract = {

Notes made by land surveyors in 1858 were utilized to estimate cover of grasses and shrubs on the Jornada Experimental Range (JER) and the Chihuahuan Desert Range Research Center (CDRRC) in the northern Chihuahuan Desert, southern New Mexico, USA. Portions of these areas have previously been assessed for historical vegetation dynamics, but the entire 84,271 ha assessed in the 19th century has not been examined in total. In 1858, fair to very good grass cover occurred on 98 and 67 percent of the JER and CDRRC, respectively. Shrubs were present throughout both properties, but 45 percent of the JER and 18 percent of the CDRRC were shrub free. Reconnaissance surveys to determine carrying capacity for livestock, made in 1915-16 and 1928-29 on the JER and in 1938 on the CDRRC, show that shrubs had made large increases in area occupied at the time of the surveys. Vegetation-type maps were made of both properties in 1998. Mesquite (Prosopis glandulosa Torrey) was the primary dominant on 59 percent of the JER in 1998, and creosotebush [Larrea tridentate (Sess. \& Moc. Ex DC.) Cov.] was the primary dominant on 27 percent of the area. On the CDRRC, mesquite and creosotebush were primary dominants on 37 and 46 percent of the area, respectively. Grass cover has decreased greatly with the increase in shrubs, and only shrub control efforts have maintained the once abundant black grama [Bouteloua eriopoda (Torrey) Torrey] as a primary dominant on 1 percent or less of the area on both properties. Sustainable use as grazing land will require low levels of use because grasses cannot increase unless shrubs are eradicated and shrub control is likely to remain economically unfeasible for the foreseeable future. http://www.sciencedirect.com/science/article/pii/S0140196304002150

}, keywords = {changes, Jornada Basin, vegetation}, doi = {10.1016/j.jaridenv.2004.10.001}, url = {/files/bibliography/05-023.pdf}, author = {Gibbens, Robert P. and R.P. McNeely and Kris Havstad and Reldon F. Beck and B. Nolen} } @article {50569, title = {Variation of soil chemical properties in irrigated and non-irrigated areas of the Laguna region of Mexico}, journal = {Terra Latinoamericana}, volume = {23}, number = {4}, year = {2005}, note = {//NONE//LTER IV//added 07/29/2005; updated 04/17/2008; PDF on file}, month = {2005}, pages = {429-436}, abstract = {

Since approximately 1840, irrigation has been required for agriculture in the Laguna Region. This activity might have changed soil chemical properties throughout time. The objective of this work was to compile soil chemical data of irrigated soils in order to document the nature and changes of soil properties. Data of organic matter, pH, electrical conductivity and cation exchange capacity from irrigated areas and non-irrigated areas of 1975 and 1997 were compared. Also, digitized soil information of the Mexican Durango and Coahuila states was examined using a Geographic Information System to obtain soil maps of the region and to locate soil sample sites. Means comparison analysis was used to statistically contrast soil parameters from non-irrigated areas against irrigated areas. Also, histograms and graphs of soil data versus depth were used to display the ranges of soil properties. The results showed that organic matter diminished by 50 percent in irrigated soils in 1997 compared with 1975; pH values increased by 6\% in irrigated soils; cation exchange capacity decreased II\% in soils under irrigation; and the electrical conductivitydid not show statistical changes.

}, keywords = {agriculture, irrigated, article, GIS, history, agriculture, history, irrigation, irrigation, history, irrigation, practices, irrigation, water table, journal, La Laguna Region, Mexico, soil properties, changes, soil, cation exchange capacity, soil, electircal conductivity, soil, nutrients, soil, organic matter, soil, pH}, url = {files/bibliography/JRN00432.pdf}, author = {Inzunza-Ibarra, Marco A. and Curtis H. Monger} } @conference {50598, title = {Validation of surface temperature determination with aster thermal infrared data}, booktitle = {European Geophysical Society; American Geophysical Union; European Union of Geosciences}, year = {2005}, month = {April 28, 2005}, publisher = {European Geosciences Union}, organization = {European Geosciences Union}, abstract = {Simultaneous observation ground brightness temperatures and the multi-spectral thermal infrared observations from the Advanced Spaceborne Thermal Emission and Reflection (ASTER) radiometer were made on 6 occasions between 2001 and 2003 at the Jornada Experimental Range in New Mexico. This arid site is well suited for the comparison because low humidity minimizes atmospheric effects. The ASTER data were atmospherically corrected using NCEP profiles adjusted for local conditions The ground measurements were made with a handheld broadband radiometer at 49 locations over a 30 x 30 m grid at 6 different sites representative of the range of land cover conditions at the Jornada. The average broadband brightness temperature was generally found to be with in the range of the brightness temperatures observed by the 5 ASTER bands.}, keywords = {ASTER, infrared, multi-spectral, temperatures, thermal}, author = {T. J. Schmugge and Jerry Ritchie and A.F. Hsu and A. Rango and A.N. French} } @conference {50704, title = {Vegetation-water budget interactions: Implications for ecosystem dynamics at multiple scales}, booktitle = {89th Annual Meeting, Ecological Society of America}, year = {2004}, month = {August 1, 2004}, pages = {p. 397}, address = {Portland, OR}, abstract = {Landscape-scale water budgets are often assumed to be driven by broad-scale gradients in topo-edaphic factors that influence run-on, runoff, and local plant available water. Feedbacks between vegetation and hydrologic processes are typically ignored. However, in arid landscapes interactions between vegetation type, soil properties, and hydrologic processes can significantly affect plant available water with effects on production at multiple scales. Our goal was to develop a framework for predicting ecologically meaningful water budgets and plant biomass for heterogeneous landscapes using information from processes operating at finer spatial scales (plant, patch). We examined the role of fine-scale vegetation-soil process interactions and topo-edaphic factors in generating patch and landscape-scale hydrology with feedbacks to vegetation. We assessed the importance of these processes on the dynamics of {\textquoteright}beads{\textquoteright}---small patches of vegetation (< 100 m2) and microtopography interspersed across Chihuahuan Desert bajada landscapes. Fine-scale processes associated with plant canopies versus bare soil areas significantly affect run-on/runoff patterns and the {\textquoteright}fate{\textquoteright} of soil water (i.e., whether water is used for plant transpiration and production or lost to evaporation). Increasing plant cover is associated with increased {\textquoteright}trapping{\textquoteright} of soil water with effects on the ratio of evaporation to transpiration. We used a spatially interactive simulation model to integrate fine-scale processes to broader scales and to predict the consequences for vegetation cover of beads and associated landscapes. The consequences of {\textquoteright}missing{\textquoteright} the presence and function of beads and other fine-scale water catchment areas in developing landscape-scale water budgets is discussed.}, author = {Debra C. Peters and K. A. Snyder and John Wainwright and A.J. Parsons} } @article {50716, title = {Viewpoint: The need for qualitative research to understand ranch management}, journal = {Journal of Range Management}, volume = {57}, year = {2004}, month = {November 2004}, pages = {668-674}, chapter = {668}, abstract = {The use and management of rangelands involves both ecological and social processes, and it is in the interaction of these that conservation is or is not achieved. Overall, the ecological dimensions of rangelands and rangeland management have been studied in greater detail and are better understood than the social dimensions. This paper argues that qualitative methods are necessary to understand the management of rangelands by ranchers. Existing studies using quantitative methods have found little correlation between ranchers{\textquoteright} management practices and a variety of social factors. One consistent finding of these studies, however, is that profit is a secondary or insignificant motivation among ranchers, casting doubt on the premise that economic self-interest motivates ranchers to embrace improved management practices. The theoretical and methodological implications of this finding have not been adequately recognized in rangeland science. With its greater flexibility and attention to context, qualitative research can reveal social, historical, political, and economic factors that affect ranch management but have eluded quantitative studies. In addition, qualitative methods are better suited to capturing both the processes that generate ranchers{\textquoteright} "mental models" and the historical information needed in light of recent theoretical advances in rangeland ecology{\textquoteright} Suggestions for future research on ranch management include conducting case studies of smaller areas over longer temporal periods, focusing on interactions among ranchers, giving ranchers a greater role in identifying research needs, studying urbanization and other "new" rangeland issues, and drawing on research about pastoralist societies elsewhere.}, keywords = {land use change, mental models, qualitative research methods, ranch management, rnachers, social processes, sustainability}, url = {/files/bibliography/04-011.pdf}, author = {N. F. Sayre} } @proceedings {50758, title = {Validation of bidirectional reflectance models using the first scene acquired by the CHRIS sensor over the Jornada Experimental Range}, volume = {VII}, year = {2003}, month = {July 21-25, 2003}, pages = {4425-4427}, address = {Toulouse, France}, abstract = {

The Compact High Resolution Imaging Spectrometer flown on the PROBA satellite on August 5, 2002, obtained multiangular reflectance data over desert grasslands and shrublands in the USDA-ARS Jornada Experimental Range near Las Cruces, NM. An experimental satellite-borne sensor, the CHRIS is one of the few sources of consistent multiangular reflectance data on kilometer scales providing up to five looks at a given target within the space of a few minutes. Two images acquired at different sun-target-sensor geometries were used to examine the validity of a simplified geometric-optical model (SGM) of bidirectional reflectance that incorporates a prior, empirical knowledge of the scattering properties of the underlying soil. The model is based on principles of geometric-optics while providing a mechanism for encapsulating volume-scattering effects. It has been subjected to sensitivity studies and tested using a radiosity-based method with simulations driven by detailed plant maps and measurements of the optical properties of plants and soils. However, up to this point it has only been tested against multiangular data acquired from the air by tilting a digital multispectral camera; work here using data from the CHRIS sensor extends and corroborates the results presented in the previous studies.

}, doi = {10.1109/IGARSS.2003.1295535}, url = {http://ieeexplore.ieee.org/iel5/9010/28607/01295535.pdf?tp=\&arnumber=1295535\&isnumber=28607}, author = {M. Chopping and L. Su and T. J. Schmugge and A. Rango} } @conference {50783, title = {Validation of an LCTA-compatible approach to military land monitoring}, booktitle = {12th Annual ITAM Workshop}, year = {2003}, month = {August 18, 2003}, pages = {72}, address = {El Paso, TX}, abstract = {A recently developed integrated soil and vegetation rangeland monitoring protocol for arid and semiarid grasslands, shrublands and savanna ecosystems has been adapted to generate LCTA-compatible data while generating additional soil and vegetation indicators that are more sensitive to changes in ecosystem function. The sampling design is also more compatible with remote sensing data. In this presentation, we present the results of three experiments: (1) a comparison between standard LCTA methods and the new protocol in several plant communities in southern New Mexico, (2) a series of studies in which the new indicators are calibrated with more intensive measurements, and (3) an experiment designed to determine the number of measurements required to detect differences with specified alpha and beta at both plot and landscape scales in different plant communities. The results indicate that a much broader suite of functions can be monitored with a relatively small increase in time cost over traditional LCTA measurements while maintaining compatibility with existing datasets.}, author = {Jeffrey E. Herrick and M. Hildegard Reiser and Laura M. Burkett and Kris Havstad} } @article {50818, title = {Variability in soil redistribution in the northern Chihuahuan Desert based on Cesium-137 measurements}, journal = {Journal of Arid Environments}, volume = {55}, year = {2003}, month = {October 1, 2003}, pages = {737-746}, abstract = {A hypothesis for understanding the stability of Northern Chihuahuan Desert landscapes is that the distribution of soil resources changes from spatially homogeneous in arid grasslands to spatially heterogeneous in invading shrublands. Since radioactive fallout Cesium-137 was deposited uniformly across the landscape during the 1950s and 1960s and was quickly adsorbed to soil particles, any redistribution of Cs-137 across the landscape would be due to soil redistribution or instability at either plant-interspaces or on a landscape scale. The concentration of Cs-137 in soils collected from different vegetation communities (black grama grass, tarbush, tobosa grass, mesquite) at the USDA-ARS Jornada Experimental Range in the Northern Chihuahuan Desert in New Mexico was determined. At the black grama grass, and tobosa grass sites, Cs-137 was uniformly distributed at the plant interspace scale. At the mesquite sites, Cs-137 was concentrated in the dune area under mesquite shrubs with little to no Cs-137 in the interdune areas. Cesium-137 data support the hypothesis that significant soil redistribution has occurred at dune sites created by invading mesquite. In the arid grassland-shrub sites with black grama grass, tobosa grass, and tarbush the Cs-137 data support the hypothesis of spatially homogeneous distribution of soil resources. High concentrations of Cs-137 in the biological soil crusts (0-5mm) at the tarbush sites indicate that biological soil crusts can contribute to the stability of these sites.}, url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-47YPJF6-1-6\&_cdi=6845\&_user=1496926\&_orig=search\&_coverDate=12\%2F31\%2F2003\&_qd=1\&_sk=999449995\&view=c\&wchp=dGLbVtb-zSkzS\&md5=b1c60b9367b54f76bcbd2c401cb62c53\&ie=/sdarticle.pdf}, author = {Jerry Ritchie and Jeffrey E. Herrick and Ritchie, C.A.} } @article {50888, title = {Vegetation and climate characteristics of arid and semi-arid grasslands in North America and their biome transition zone}, journal = {Journal of Arid Environments}, volume = {51}, number = {1}, year = {2002}, month = {May 1, 2002}, pages = {55-78}, abstract = {

The objective of this study was to investigate the relationship among species richness, functional group composition, and climate for three sites representing the shortgrass steppe, the Chihuahuan desert grasslands, and their biome transition zone. We found perennial species richness increased as the climate became more favorable for plant growth. The biome transition zone was more similar to the Chihuahuan desert grassland site i most climate and vegetation characteristics, partly because of the shorter biogeographic distance between the two sites. This study clarified the ecological position of the biome transition zone site with respect to the adjacent biomes.

}, keywords = {annuals, Chihuahuan Desert grasslands, ECOTONE, perennials, Regional analysis, shortgrass steppe, species area curve}, doi = {10.1006/jare.2001.0929}, url = {/files/bibliography/02-038.pdf}, author = {Hochstrasser, T. and G. Kroel-Dulay and Debra C. Peters and J. R. Gosz} } @conference {50916, title = {Volatile compositions of root-borer infested and uninfested samples of Gutierrezia sarothrae (broom snakeweed)}, booktitle = {55th Annual Meeting, Society for Range Management}, year = {2002}, month = {2002}, pages = {8}, abstract = {Snakeweed (Gutierrezia sarothrae) is an abundant range subshrub in the western United States. Toxic to cattle and sheep, this plant is considered highly undesirable in the rangeland ecosystem. Much research has been carried out in an attempt to control or eliminate snakeweed. To date, no method has been satisfactorily effective. Snakeweed has two root-boring beetles that tunnel within the plant to develop. These grubs, Crossidius pullchellus (Coleoptera: Cerambycidae) and Myrmex linneolata (Coleoptera: Curculionidae) can cause much physical damage to snakeweed, but little is known about the chemical plant-insect interaction. In this study, we have used gas chromatography-mass spectroscopy (GC/MS) and GC-FID to identify and quantify differences in volatile chemicals present in snakeweed samples with and without root borers. At present, 81 volatile compounds have been identified, many of which have not been previously reported in snakeweed. Values of these compounds present in each group of samples are reported here. Statistical analysis is currently underway to determine the significance of differences in the levels of these chemicals between samples.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, proceeding, proceedings}, author = {Morrison, A. and M.E. Lucero and E.L. Fredrickson and M.D. Remmenga and D. Richman} } @article {50919, title = {Vegetation influences on water yields from grassland and shrubland ecosystems in the Chihuahuan desert}, journal = {Earth Surface Processes and Landforms}, volume = {27}, year = {2002}, note = {//NMSU//LTER-IV//}, month = {2002}, pages = {1011-1020}, abstract = {

This study examines runoff generated under simulated rainfall on Summerford bajada in the Jornada Basin, New Mexico, USA. Forty-five simulation experiments were conducted on 1 m2 and 2 m2 runoff plots on grassland, degraded grassland, shrub and intershrub environments located in grassland and shrubland communities. Average hydrographs generated for each environment show that runoff originates earlier on the vegetated plots than on the unvegetated plots. This early generation of runoff is attributed to soil infiltration rates being overwhelmed by the rapid concentration of water at the base of plants by stemflow. Hydrographs from the degraded grassland and intershrub plots rise continuously throughout the 30 min simulation events indicating that these plots do not achieve equilibrium runoff. This continuously rising form is attributed to the progressive development of raindrop-induced surface seals. Most grassland and shrub plots level out after the initial early rise indicating equilibrium runoff is achieved. Some shrub plots, however, display a decline in discharge after the early rise. The delayed infiltration of water into macropores beneath shrubs with vegetation in their understories is proposed to explain this declining form. Water yields predicted at the community level indicate that the shrubland sheds 150\% more water for a given storm event than the grassland. Copyright {\textcopyright} 2002 John Wiley \& Sons, Ltd.

}, keywords = {article, articles, hydrology, ecosystem dynamics, hydrology, grassland, hydrology, processes, hydrology, rainfall simulation, hydrology, shrubland, hydrology, water budget, hydrology, water yield, hydrology,infiltration, hydrology,runoff, journal, journals, runoff, stemflow, Larrea, water yield}, doi = {10.1002/esp.389}, url = {files/bibliography/JRN00374.pdf}, author = {Melissa Neave and Athol D. Abrahams} } @proceedings {50963, title = {Virtual fencing - a prescription range animal management tool for the 21st century}, year = {2001}, month = {March 12-13, 200}, pages = {85-94}, address = {Aberdeen, Scotland}, abstract = {Optimum forage utilization requires herbivores to be moved periodically commensurate with the landscape{\textquoteright}s productivity. Stationary conventional fencing has been tried alone and with other tools and techniques to affect animal distribution and forage utilization; none consistently permit flexible management in real time. Virtual fencing has the potential to automate animal management and provide autonomous animal control. Virtual fencing systems require animals to wear an electronics package that includes hardware, software and an antenna to receive radio frequency (RF) signals. A patented virtual fence device is described that uses RF signals emanating from navigation satellites of the Global Positioning System (GPS). These signals are used to locate the animal{\textquoteright}s geographic location and can be logged at programmable intervals of 1 second or more. They are used to build virtual fences that can be programmed to take any geometrical shape, manipulated in space and time and surround areas as wel as individuals. The unit{\textquoteright}s Geographic Information System (GIS) data continuously compares the animal{\textquoteright}s location and angle of approach to that of the closest virtual fence. Should an animal attempt to penetrate a virtual fence, algorithms within the unit{\textquoteright}s central processing unit determine the suite of programmable cues to apply to the animal{\textquoteright}s left or right side to maximize the animal{\textquoteright}s distance of separation from a virtual fence in the least amount of travel. The cues begin with the least and progresses to the most aversive, depending on the animal{\textquoteright}s proximity to the virtual fence. If the animal fails to respond at the highest level of cuing, the unit shuts down in a failsafe manner to prevent unnecessary stress to the animal.}, keywords = {automate animal management, autonomous animal control, Global Positioning System, radio frequency signals, virtual fencing}, url = {/files/bibliography/01-002.pdf}, author = {D.M. Anderson} } @article {51076, title = {Variation in body temperature and thermoregulatory behavior between two populations of the lesser earless lizard, Holbrookia maculata}, journal = {Contemporary Herpetology}, volume = {2000}, number = {1}, year = {2000}, note = {//NMSU,OTHER//NONE// Retrieved from online March 28, 2000}, month = {2000}, abstract = {Body temperatures and thermoregulatory behavior of field-active Holbrookiamaculata were evaluated for two sites at approximately equal elevation (approximately1200 m) in southern New Mexico: 1) a population at White Sands National Monument, and 2) a population at the Jornada Long-term Ecological Research site. H.maculata at WS had significantly lower body temperatures (mean = 36.3{\textdegree}C) than those measured at the Jornada Long-term Ecological Research site (mean = 39.5{\textdegree}C). The slope of a regression of body temperature on air temperature was significantly different between populations (White Sands National Monument; 0.65, the Jornada Long-term Ecological Research site; 0.36). The microhabitats in which individuals were first observed correlated with body temperatures at White Sands National Monument, but not at the Jornada Long-term Ecological Research site. ~ These data suggest that environmental temperature differences between sites influenced body temperatures and thermoregulation in behavior H.maculata.}, keywords = {article, articles, journal, journals, lizard, Holbrookia, lizard, physiology, lizard, thermoregulation, physiology, reptiles, White Sands, lizard}, isbn = {1094-2246}, url = {http://eagle.cc.ukans.edu/~cnaar/CH/ch/2000/1/index.htm //This is an online journal. There are no other type of reprint.}, author = {Hager, Stephen B.} } @article {51091, title = {Variability in soil heat flux from a mesquite dune site}, journal = {Agricultural and Forest Meteorology}, volume = {103}, year = {2000}, note = {//USDA//LTER III//}, month = {2000}, pages = {249-264}, abstract = {

For many natural and agricultural landscapes, vegetation partially covers the ground surface, resulting in significant variations in soil heat flux between interspace areas and underneath vegetation. This is particularly apparent in arid and semiarid regions where vegetation cover is low and clustered or {\textquoteright}clumped{\textquoteright} with large areas of exposed soil. Surface heterogeneity presents significant challenges to the use of standard micro-meteorological measurement techniques for estimating surface energy balance components. The objective of this study was to use an array of 20 soil heat flux plates and soil temperature sensors to characterize the spatial and temporal variability in soil heat flux as affected by vegetation and micro-topographic effects of mesquite dunes in the Jornada Experimental Range in southern New Mexico. Maximum differences in soil heat flux among sensors were nearly 300 W m-2. Maximum differences among individual sensors under similar cover conditions (i.e., no cover or interdune, partial or open canopy cover and full canopy cover) were significant, reaching values of 200-250 W m-2. The {\textquoteright}area-average{\textquoteright} soil heat flux from the array was compared with an estimate using three sensors from a nearby micro-meteorological station. These sensors were positioned to obtain soil heat flux estimates representative of the three main cover conditions: namely, no cover or interdune, partial or open canopy cover, and full canopy cover. Comparisons between the array-average soil heat flux and the three-sensor system indicate that maximum differences on the order of 50 to nearly 100 W m-2 are obtained in the early morning and mid-afternoon periods, respectively. These discrepancies are caused by shading from the vegetation and micro-topography. The array-derived soil heat flux also produced a significantly higher temporal varying soil heat flux/net radiation ratio than what has been observed in other studies under more uniform cover conditions. Results from this study suggest that, to determine the number and location of sensors needed for estimating area-average soil heat flux in this type of landscape, one needs to account not only for the clustering of the vegetation cover but also micro-topography. Published by Elsevier Science B.V.

}, keywords = {article, articles, JORNEX, soil heat flux, journal, journals, mesquite dune, soil heat flux, remote sensing, JORNEX, soil heat flux, JORNEX, soil heat flux, mesquite dune}, doi = {10.1016/S0168-1923(00)00131-3}, url = {files/bibliography/JRN00315.pdf}, author = {William P. Kustas and J.H. Prueger and J. Hatfield and K. Ramalingam and Lawrence E. Hipps} } @conference {51177, title = {Vegetation-soil feedbacks and sensitivity of Chihuahuan Desert ecosystem boundaries to climate change}, booktitle = {84th Annual Meeting, Ecological Society of America}, volume = {80}, year = {1999}, month = {August 8-12, 199}, pages = {69}, address = {Spokane, WA}, abstract = {

Geographic distributions of species and ecosystems are predicted to shift with regional and global changes in climate. Our objective was to predict changes in the regional distribution of Chihuahuan desert grasslands using a landscape-scale approach that incorporates vegetation-soil feedbacks. We used a spatially-explicit individual plant-based model to simulate vegetation responses at locations differing in species composition, soils, and climate. The model incorporates feedbacks among vegetation and soil properties and processes that are important to perennial grass establishment and survival. We used the model to predict the landscape and regional locations most likely to shift from shrub- to grass-dominated vegetation in response to changes in climate. Because climate and texture vary at different scales, our results generated a complex mosaic of sensitivity of these ecosystems to climate change. Soil texture was more important than initial soil organic matter content in the shift from shrub to grasses. Feedbacks between soil organic matter and changes in species composition increased the rate of this change. Our results demonstrate the importance of including landscape-scale variability in vegetation and soil processes in predicting ecosystem boundary shifts in response to global climate change.

}, author = {Debra C. Peters and Jeffrey E. Herrick} } @article {51205, title = {Vulnerability of desert soil surfaces to wind erosion: the influences of crust development, soil texture, and disturbance}, journal = {Journal of Arid Environments}, volume = {39}, year = {1998}, note = {//??//LTER-III//}, month = {1998}, pages = {133-142}, keywords = {article, articles, disturbance, wind, journal, journals, soil properties, soil texture, wind erosion}, author = {Jayne Belnap and D. E. Gillette} } @conference {51227, title = {Vegetation structure at a grassland-shrubland ecotone: Biotic versus abiotic factors leading to shrub invasion}, booktitle = {83rd Annual Meeting, Ecological Society of America}, volume = {79}, year = {1998}, month = {1998}, pages = {71}, address = {Baltimore, Maryland}, abstract = {The invasion of serai-arid grasslands in the Southwestern US by shrubs is usually attributed to the complex interactions between grazing, climate, and fire. However, different soils may have different sensitivities to invasion, such that shrubs would be confined to certain sites. Our objective was to evaluate the relationship between vegetation structure and variation in soil characteristics for a 500m x l00m grid across a grassland-shrubland transition zone. Soil samples to a depth of 30cm were taken from 10 x l0m quadrats and cover of the dominant species as well as importance of disturbance was assessed. Shrub cover was higher when die soil was shallower on a l0 xl0m scale. Vegetation and soil sampling around individual plants revealed that the probability of germination of shrub seedlings was higher within the canopy area of the shrub than it was in the interspaces, indicating that the microclimate and soil were more favorable around the adults. These results suggest that the shrub invasion took place mainly on soil less favorable for grassland. These favorable microsites may support a source population of shrubs for further spread in the landscape.}, author = {Hochstrasser, T. and D.P. Coffin} } @inbook {51256, title = {Validation of indicators}, booktitle = {Ecosystem Health}, year = {1998}, month = {1998}, pages = {205-209}, publisher = {Blackwell Science, Inc.}, organization = {Blackwell Science, Inc.}, chapter = {12}, address = {Malden, MA}, abstract = {

Assessing the health of any ecosystem requires the measurement of a number of indicators. For an assessment of ecosystem health to have real value, it must not only address status, but also evaluate the risk of that status changing to a less healthy state. Although numerous indicators of ecosystem health have been proposed (Rapport et al 1985; National Research Council 1993), few have been tested to date. Such testing must incorporate evaluation of the indicator{\textquoteright}s sensitivity so as to provide unambiguous and reliable values for the assessment of ecosystem status. Indicator sensitivity must also be known so as to enable an evaluation of the risk of change in the health status of the ecosystem.

}, url = {/files/bibliography/640.pdf}, author = {Walter G. Whitford}, editor = {D. J. Rapport and Costanza, R. and Epstein, P.R. and C. Gaudet and Levins, R.} } @article {51255, title = {Vegetation, soil, and animal indicators of rangeland health}, journal = {Environmental Monitoring Assessment}, volume = {51}, year = {1998}, month = {June 1, 1998}, pages = {179-200}, abstract = {

We studied indicators of rangeland health on benchmark sites with long, well documented records of protection from stress by domestic livestock or histories of environmental stress and vegetation change. We measured ecosystem properties (metrics) that were clearly linked to ecosystem processes. We focused on conservation of soil and water as key processes in healthy ecosystems, and on maintenance of biodiversity and productivity as important functions of healthy ecosystems. Measurements from which indicators of rangeland health were derived included: sizes of unvegetated patches, cover and species composition of perennial grasses, cover and species composition of shrubs and herbaceous perennials, soil slaking, and abundance and species composition of the bird fauna. Indicators that provided an interpretable range of values over the gradient from irreversibly degraded sites to healthy sites included: bare patch index, cover of long-lived grasses, palatability index, and weighted soil surface stability index. Indicators for which values above a threshold may serve as an indicator of rangeland health include: cover of plant species toxic to livestock, cover of exotic species, and cover of increaser species. Several other indicator metrics were judged not sensitive nor interpretable. Examples of application of rangeland health indicators to evaluate the success of various restoration efforts supported the contention that a suite of indicators are required to assess rangeland health. Bird species diversity and ant species diversity were not related to the status of the sample site and were judged inadequate as indicators of maintenance of biodiversity.

}, doi = {10.1023/A:1005987219356}, url = {/files/bibliography/641.pdf}, author = {Walter G. Whitford and A.G. de Soyza and Justin Van Zee and Jeffrey E. Herrick and Kris Havstad} } @article {51304, title = {Variation in Creosotebush (Larrea tridentata) canopy morphology in relation to habitat, soil fertility and associated annual plant communities}, journal = {American Midland Naturalist}, volume = {137}, year = {1997}, month = {1997}, pages = {13-26}, abstract = {

Differences in creosotebush (Larrea tridentata) crown morphology may reflect chances in relative demand for water vs. nutrient resources, coinciding with shrub growth and development. Creosotebushes with inverted, cone-shaped crowns were more abundant in water-limited environments; whereas, hemispherical-shaped creosotebushes were more abundant in less water-limited environments. Cone-shaped creosotebushes accumulated substantially less litter under their canopies than did creosotebushes with hemispherical-shaped crowns. Soil nutrient concentrations under conical shrubs were similar to those in intershrub spaces and both of these were less than soil nutrient concentrations under hemispherical shrubs. In ecosystems where overland flow of water exerted a greater influence on movement of organic litter than did wind, shrub shape had little effect on long-term litter accumulation. No persistent differences in the biomass or diversity of ephemeral taxa exploiting undershrub areas were found, probably because the positive effects of greater nutrient resources under hemispherical shrubs were offset by the limitations imposed by the larger, more dense canopies of hemispherical shrubs. Overall, creosotebush morphology affected litter accumulation patterns and soil nutrient patterns and must be considered when assessing the heterogeneity of desert ecosystems in the southwestern U.S.

}, keywords = {desert soils, deserts, nitrogen, Plant morphology, plants, shrubs, soil morphology, soil nutrients, Stems, Vegetation canopies}, doi = {10.2307/2426751 }, url = {/files/bibliography/510.pdf}, author = {A.G. de Soyza and Walter G. Whitford and E. Martinez-Meza and Justin Van Zee} } @article {51427, title = {Variability in soils and vegetation associated with harvester ant (Pogonomyrmex rugosus) nests on a Chihuahuan Desert watershed}, journal = {Biology and Fertility of Soils}, volume = {20}, year = {1995}, month = {1995}, pages = {169-173}, abstract = {

The effects of harvester ant (Pogonomyrmex rugosus) nests on the density and cover of spring annual plants and on soil characteristics were measured at three locations characterized by different soils and dominant vegetation on a desert watershed. There were few differences in vegetation and soils associated with harvester ant nests at locations at the base of the watershed where brief periods of flooding and sediment deposition occur at periodic intervals. At mid-slope locations, there were significant increases in total nitrogen, inorganic phosphorus, and cover (biomass) of four species of spring annuals at the edges of nest disks when compared with reference sites. The spring annuals that exhibited increased cover were species that increase biomass as a function of available nitrogen. At a clay-loam, Scleropogon-Hilaria, grassland site, there were significant reductions in the concentrations of Ca2+ and Mg2+, significant increases in nitrate and total nitrogen, but a significant increase in cover in only one species of annual plant. The data demonstrate that the effects of ants on soil properties and vegetation vary with site location and soil type.

}, keywords = {annual plants, desert, Harvester ants, Pogonomyrmex rugosus, soil nutrients, spatial variability}, doi = {10.1007/BF00336554}, url = {/files/bibliography/463.pdf}, author = {Walter G. Whitford and DiMarco, R.} } @inbook {51462, title = {The vulnerability of biotic diversity}, booktitle = {Industrial Ecology}, year = {1994}, note = {//NONE//LTER III//ProCite field[6]: In}, month = {1994}, pages = {245-260}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, abstract = {

The presence or absence of a single species can cause a dramatic change in ecosystems,
but our ability to predict which species can cause such change is limited. The
disappearance of species can indicate changes in the ability of an ecosystem to sustain life
over a long period of time. While there is an enormous literature on the losses of species
associated with various industrial activities, the focus here is on changes in the earth{\textquoteright}s
atmosphere that may cause biotic impoverishment.

}, keywords = {biodiversity, book, books, chapter, chapters, report, reports}, author = {W. H. Schlesinger}, editor = {Socolow, R. and Andrews, C. and Berkhout, F. and Thomas, V. (eds.)} } @article {51463, title = {Variation of clonal, mesquite-associated rhizobial and bradyrhizobial populations from surface and deep soils by symbiotic gene region restriction fragment length polymorphism and plasmid profile analysis}, journal = {Applied and Environmental Microbiology}, volume = {60}, number = {4}, year = {1994}, note = {//OTHER//LTER//Listed in LTER3 proposal as citing LTER2 support//}, month = {1994}, pages = {1146-1153}, abstract = {

Genetic characteristics of 14 Rhizobium and 9 Bradyrhizobium mesquite (Prosopis glandulosa)-nodulating strains isolated from surface (0- to 0.5-m) and deep (4- to 6-m) rooting zones were determined in order to examine the hypothesis that surface- and deep-soil symbiont populations were related but had become genetically distinct during adaptation to contrasting soil conditions. To examine genetic diversity, Southern blots of PstI-digested genomic DNA were sequentially hybridized with the nodDABC region of Rhizobium meliloti, the Klebsiella pneumoniae nifHDK region encoding nitrogenase structural genes, and the chomosome-localized ndvB region of R. meliloti. Plasmid profile and host plant nodulation assays were also made. Isolates from mesquite nodulated beans and cowpeas but not alfalfa, clover, or soybeans. Mesquite was nodulated by diverse species of symbionts (R. meliloti, Rhizobium leguminosarum bv. phaseoli, and Parasponia bradyrhizobia). There were no differences within the groups of mesquite-associated rhizobia or bradyrhizobia in cross-inoculation response. The ndvB hybridization results showed the greatest genetic diversity among rhizobial strains. The pattern of ndvB-hybridizing fragments suggested that surface and deep strains were clonally related, but groups of related strains from each soil depth could be distinguished. Less variation was found with nifHDK and nodDABC probes. Large plasmids (\>1,500 kb) were observed in all rhizobia and some bradyrhizobia. Profiles of plasmids of less than 1,000 kb were related to the soil depth and the genus of the symbiont. We suggest that interacting selection pressures for symbiotic competence and free-living survival, coupled with soil conditions that restrict genetic exchange between surface and deep-soil populations, led to the observed patterns of genetic diversity.

}, keywords = {article, articles, bradyrhizobia, genetics,bradyrhizobia, genetics,rhizobia, journal, journals, plasmid profile analysis, Prosopis,bradyrhizobia, Prosopis,rhizobia, rhizobia, root,Prosopis rhizobia, soil,bradyrhizobia, soil,rhizobia}, url = {files/bibliography/JRN00182.pdf}, author = {P. M. Thomas and K. F. Golly and Judith W. Zyskind and R. A. Virginia} } @article {51646, title = {Vegetation patterns, microtopography and soils on a Chihuahuan desert playa}, journal = {Journal of Vegetation Science}, volume = {1}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {403-410}, abstract = {

Spatial patterns of vegetation on an ephemeral lake bed (playa) in the northern Chihuahuan desert were closely correlated with elevation. Distributions of species along a 265 m transect from the center to the edge of the playa showed abrupt boundaries at 110 m and 220 m. These boundaries seem related to the maximum elevation covered with standing water following complete flooding, and to an edaphic boundary between heavy clay soils at the center of the playa and adjacent soils. The complete turnover in species composition across this transect, with an elevation change of only 85 cm, indicates that environmental gradients resulting from flooding and soil development are steep. Vegetative patterns within the lowest part of the playa were patchy, with patch diameters ranging from 2 to 5 m. These patches appear to be produced by differences in the duration and frequency of flooding between small knolls and depressions resulting from gilgai microtopography.

}, keywords = {article, articles, ephemeral lakebed, SEE , journal, journals, microtopography, gilgai, playa, flooding, playa, microtopography, playa, soils, playa, vegetation patterns, soil, playa, topo-edaphic gradient}, doi = {10.2307/3235717}, url = {files/bibliography/JRN00133.pdf}, author = {Steven M. Wondzell and Joe M. Cornelius and Gary L. Cunningham} } @conference {51760, title = {Vegetation parameters inside and outside livestock exclosures on three Chihuahuan Desert grassland communities}, booktitle = {40th Annual Meeting, Society for Range Management}, year = {1987}, month = {1987}, pages = {34}, author = {T.L. Atwood and Reldon F. Beck and Gibbens, Robert P.} } @article {51782, title = {Variation in insect densities on desert creosotebush: is nitrogen a factor?}, journal = {Ecology}, volume = {68}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1987}, pages = {547-557}, abstract = {

A field experiment was conducted to assess the effects of nitrogen and water on the densities and taxonomic and trophic compositions of arthropods on the foliage of desert creosotebush (Larrea tridentata). Nitrogen and water were manipulated through a series of fertilizer and irrigation treatments applied to naturally growing creosotebush shrubs at a site in the northern Chihuahuan Desert. Water with nitrogen, and nitrogen fertilization alone, significantly increased creosotebush foliage production and foliar nitrogen contents. Foliage production, foliar nitrogen contents, and numbers of foliage arthropods were all higher in the late spring than in the mid or late summer. Numbers of foliage arthropods increased significantly on fertilized plants in the late spring. Water treatments alone had no effect on numbers of foliage arthropods, but a positive water-fertilizer interaction effect on numbers of foliage arthropods was evident in the late spring. Overall, there were significant positive correlations between foliage production, foliar nitrogen contents, and foliage arthropod densities. Photophagous sap-sucking insects accounted for the majority of arthropods on creosotebush, and their densities varied most in relation to foliage production and foliar nitrogen contents. Results of our study demonstrated that sap-sucking phytophagous insects are more responsive than leaf-chewing insects to increased nitrogen content of creosotebush foliage, and that much of the between-plant variation in densities of phytophagous insects within a stand of creosotebush may be due to sap-sucking insects tracking variable foliar nitrogen.

}, keywords = {arthropod, Larrea, arthropod, list, article, articles, insect, phytophagous, journal, journals, Larrea, arthropods, list, arthropod, nitrogen amendment, nitrogen, Larrea, phytophagous insect, rainfall simulation, water amendment}, doi = {10.2307/1938460 }, url = {files/bibliography/JRN00064.pdf}, author = {David C. Lightfoot and Walter G. Whitford} } @article {51802, title = {Variation of soil and vegetation with distance along a transect in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {13}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//updated 6/22/2010; pdf available}, month = {1987}, pages = {53-63}, abstract = {

The number of systematic studies of the coincidence of soil and vegetation zones in arid areas is relatively limited. In this study the spatial variability of soil morphological characteristics, soil moisture and vegetation were determined along a 3-km transect in the Chihuahuan Desert in southern New Mexico. There is extensive spatial variability in soil physical properties, in water content and in vegetation along the transect. However, using a multivariate technique, it was found that this spatial variability could be partitioned into distinct zones. The boundaries between zones based on soil morphological characteristics coincide closely with boundaries based on soil water content and those based on vegetation. It is concluded that the multivariate moving split-window technique is a valuable tool for evaluating soil and vegetation boundaries along transects.

}, keywords = {article, articles, journal, journals, soil, soil moisture,transect, soil morphology, soil, spatial variability, technique, moving split window, transect, soil moisture, transect,soil variation, transect,vegetation variation, vegetation, vegetation, spatial variability}, url = {files/bibliography/JRN00065.pdf}, author = {Peter J. Wierenga and Jan M. H. Hendrickx and M. H. Nash and J. Ludwig and LeRoy A. Daugherty} } @conference {51814, title = {Vegetation changes following 20 years of protection on black grama sites originally grazed at four intensities}, booktitle = {39th Annual Meeting, Society for Range Management}, year = {1986}, month = {1986}, pages = {110}, keywords = {black grama sites, changes, vegetation}, author = {Reldon F. Beck and T.L. Atwood and Gibbens, Robert P.} } @proceedings {51828, title = {Vegetation and community types of the Chihuahuan Desert}, year = {1986}, note = { //LOCAL//NONE//ProCite field[6]: In}, month = {10/1986}, pages = {20-39}, publisher = {Allen Press}, address = {Chihuahuan Desert Research Institute, Sul Ross State University}, abstract = {

A classification of plant communities of the Chihuahuan Desert Region, inclusive of all montane habitats is presented. A total of 16 intergrading communities is recognized including eight Desert Scrub and Woodland communities: Chihuahuan Desert Scrub (with 5 facies), Lechuguilla Scrub, Yucca Woodland, Prosopis-Atriplex Scrub, Alkali Scrub, Gypsophilous Scrub, Arborescent Cactus Scrub, and Riparian Woodland; three Grassland communities: Grama Grassland, Sacaton Grassland, and Tobosa Grassland; a Chaparral community: Montane Chaparral; and four Montane Woodland communities: Juniper-Pinyon Woodland, Oak Woodland, Pine Woodland, and Mixed Fir Forest.\ 

}, keywords = {abstract, abstracts, chaparral community, community types, conference, conference proceedings, conferences, grassland community, montane chaparral community, montane woodland community, proceeding, proceedings, shrub community, vegetation types, woodland community}, url = {files/bibliography/JRN00116.pdf}, author = {Henrickson, James and Johnston, Marshall C.}, editor = {Barlow, Jon C. and Michael A. Powell and Timmermann, Barbara N. (eds.)} } @proceedings {51830, title = {Vegetation changes on arid rangelands of the southwestern United States}, year = {1986}, month = {1986}, pages = {8-10}, address = {Adelaide, Australia}, abstract = {

Vegetation changes on arid rangelands of the southwestern United States in the last 100 years are described. Reasons and solutions to the problems resulting from these changes are discussed. Shrubs have increased dramatically with a corresponding reduction of herbaceous plants. Encroachment of woody plants into previously shrubless areas is closely correlated with man{\textquoteright}s activities combined with drought. Man has been a disturber of natural systems and his ability to create disturbances has increased as technology has increased. Increased use of arid rangelands of the southwestern United States is possible with intensive practices such as brush control, revegetation where needed, and improved grazing management.

}, url = {/files/bibliography/295.pdf}, author = {C.H. Herbel} } @mastersthesis {51858, title = {Variation in diurnal ant species composition and relative abundance on a desert watershed}, year = {1986}, note = {//NMSU//LTER I//}, month = {1986}, pages = {59}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Variation in ant species composition and relative abundance was studied on a desert watershed 45 km NNE of Las Cruces, New Mexico.... The results of this study suggest that the community structure investigated is the result of individual species{\textquoteright} responses to their physical environment. They also suggest that species response to their physical environment may play a more direct role in structuring communities than modification of competitive relations between species as suggested by the view of desert ant communities structured by interspecific exploitive competition.}, keywords = {ant community, species composition, ant, species composition, community, ant species composition, dissertation, dissertations, insect, ant, theses, thesis}, author = {Steven Scott Van Vactor} } @article {51884, title = {Vegetation changes on arid rangelands of the Southwest}, journal = {Rangelands}, volume = {7}, year = {1985}, month = {1985}, pages = {19-21}, abstract = {

Change, an inherent characteristic of ecosystems, is a recognized feature of vegetation in the arid and semiarid portions of the southwestern United States. Territorial surveys in the 19th century and terrestrial photography in the 19th century and early 20th century have been used to establish a base for vegetation conditions and then for recording variations from this base. All evidence indicates a dramatic shift from land with a high proportion of grassy vegetation to one dominated by shrubs. Most of these changes have occurred in the last 50-100 years. Following are some of the reasons and possible solutions to problems resulting from these changes that would be applicable to parts of Arizona, New Mexico, and Texas, with possible use in other arid and semiarid regions of the world.

}, url = {/files/bibliography/278.pdf}, author = {C.H. Herbel} } @article {51948, title = {Vegetation changes from 1935 to 1980 in mesquite dunelands and former grasslands of southern New Mexico}, journal = {Journal of Range Management}, volume = {36}, number = {3}, year = {1983}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {May 1, 1983}, pages = {370-374}, abstract = {

On the Jornada Experimental Range in southern New Mexico, 2 belt transects, 30.5 cm in width and totaling 2,l88 m length, were established in 1935 on 2 areas where honey mesquite (Prosopis glandulosa Torr.) was spreading into black grama [Bouteloloua eriopoda (Torr.) Torr.] grassland. Maps were made of the transects which portrayed the vegetation occurring in each of the 7,180 contiguous, 0.09-m2 \ plots along the transect. The vegetation on the transects in 1980 was compared to that portrayed by the transect maps made in 1935. One transect bad been read in 1950 and 1955. During the 45-year period mesquite attained complete dominance and many new mesquite dunes formed. Black grama had a relatively high frequency in 1935 but had completely disappeared by 1980, both on an area grazed by livestock and on an area protected from grazing. Mesa dropseed [Sporobolus flexuosus (Thurb.) Rydb.], fluff grass [Erioneuron pulchelbum (H.B.K.) Tateoka] and broom snakeweed [Xanthocephalum sarothrae (Pursh) Shinners] increased in abundance, even during the drought period between 1950 and 1955. Only 25\% of the perennial forb species encountered in 1935-55 were found in 1980.

}, doi = {10.2307/3898490}, url = {/files/bibliography/235.pdf}, author = {J.T. Hennessy and Gibbens, Robert P. and J.M. Tromble and Manual Cardenas} } @conference {51986, title = {Vegetation and edaphic influences on infiltration rates in arid and semiarid rangelands}, booktitle = {American Society of Agricultural Engineers, Conference on Advances in Infiltration}, year = {1983}, month = {1983}, pages = {385}, address = {Chicago, IL}, author = {Wood, M. K. and Weitz, M. and J.M. Tromble} } @proceedings {52001, title = {Verification of a continuous flow fermentation system and effect of dilution rate on rumen fermentation and microbial numbers}, volume = {33}, year = {1982}, month = {1982}, pages = {29-31}, keywords = {fermentation, micorbial, rumen}, url = {/files/bibliography/82-002.pdf}, author = {Richard E. Estell and Galyean, M.L. and Melchor Ortiz and Leighton, E.A.} } @article {52049, title = {Validation of primary production model of the desert shrub Larrea tridentata using soil-moisture augmentation experiments}, journal = {Oecologia}, volume = {51}, year = {1981}, note = {//NMSU//US-IBP//}, month = {1981}, pages = {357-363.}, abstract = {In previous papers we have described and verified a primary production model of the desert shrub Larrea tridentata. Here we address the validation phase of the evaluation of this model. Two versions of the model which differ in the priority scheme used for allocating carbon to reproductive or vegetative organs were compared on the basis of their usefulness and reliability over a range of soil-moisture conditions. Over an entire growing season when soil-moisture conditions were near "normal" both versions of the model were adequate predictors of total above-ground vegetative growth and one was an adequate predictor of reproductive growth as well. A more detailed analysis revealed that the versions varied in the range of soil-moisture conditions over which they were adequate and that neither was adequate when soil-moisture had remained high for extended periods. The validation process has revealed some likely areas for model improvement to increase adequacy.}, keywords = {article, articles, journal, journals, Larrea,productivity model, Larrea,soil-moisture augmentation, model, Larrea, model,primary production, plant, Larrea, rainfall simulation,Larrea}, author = {J. F. Reynolds and Gary L. Cunningham} } @article {52136, title = {Vegetation and soil patterns on a Chihuahuan Desert bajada}, journal = {The American Midland Naturalist}, volume = {101}, number = {1}, year = {1979}, note = {//NMSU//US-IBP//}, month = {1979}, pages = {28-37}, abstract = {Vegetation and soils were sampled along a 1100-m transect on a bajada in southern New Mexico to determine if present vegetation patterns can be interpreted from soil patterns. Species cover was measured in 66 plots, each 50.3 m2. Of these, 22 were randomly chosen as sites for soil pits, which were described and analyses conducted on the top (A1) horizon. The plots were clustered into four communities: Erioneuron pulchellum desert grassland transition, Larrea tridentata desert shrub, Bouteloua curtipendula semidesert grassland and Bouteloua eriopoda desert grassland. Soils of these communities differ significantly in pH, Mg, organic carbon and total nitrogen. These soil chemistry differences could be due to relatively recent changes from Bouteloua grassland and Larrea shrubland, as indicated by our dead shrub data and as documented for many bajadas in southern New Mexico. However, soil series and geomorphic surface patterns, which are not readily affected by recent vegetation changes, suggest that Larrea may always have been an important shrub on shallow calcareous soils (of erosional surfaces) in southern New Mexico. Its importance as a mosaic type in the once extensive desert grasslands has probably been underestimated.}, keywords = {article, articles, biogeochemistry,soil patterns, journal, journals, soil geomorphology, soil patterns, soil, nitrogen, transect,soil patterns, transect,vegetation patterns}, author = {Rebecca A. Stein and J. Ludwig} } @article {52147, title = {Vegetative and reproductive growth patterns in desert willow (Chilopsis linearis (Cav.) Sweet)}, journal = {The Southwestern Naturalist}, volume = {23}, number = {2}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {239-246}, abstract = {The patterns of leaf and fruit production of desert willow, Chilopsis linearis (Cav.) Sweet, in relation to temperature and precipitation pattterns in the Chihuahuan Desert of southern New Mexico were examined by harvesting shoot samples monthly during four growing seasons. On a site with 1.1 individuals per hectare, leaf production was about 5 kg.ha-1 in two years with dry springs and moist summers. In a year with a moist spring and a moist summer, leaf and fruit production was doubled. This high rate of production in the field during favorable periods supports previous laboratory studies that Chilopsis has a high acclimation potential under cool to moderate temperatures. However, in a year with a hot, dry spring and summer Chilopsis was adversely affected. This also supports previous studies that the net photosynthesis rate of Chilopsis was greatly reduced under high preconditioning temperatures and rapidly decreased as water potentials dropped below -10 bars.}, keywords = {article, articles, Chilopsis,productivity, Chilopsis,reproduction, journal, journals, plant, desert willow, Chilopsis, plant,Chilopsis, reproduction,Chilopsis}, author = {Elaine DePree and J. Ludwig} } @mastersthesis {52193, title = {Vegetation and soil patterns on Chihuahuan Desert bajada}, year = {1977}, note = {//NMSU//US-IBP//}, month = {1977}, pages = {67}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Vegetation an soils were sampled along a 1100 meter transect on a bajada in southern New Mexico in an effort to determine if present vegetation patterns are reflected in the soil.... It is thought that a hundred years ago this area was a grassland covered predominantly by Bouteloua sp. with scattered shrubs. present vegetational patterns are very different and this may be due to disturbance by grazing, which decrease the grass cover and opened areas to shrubs. In present Larrea tridentata areas, data for nitrogen and organic carbon indicate a significant deterioration of the original soils. It was observed on the study site that soil erosion was more extensive in the Larrea tridentata community than in the grassland communities.}, keywords = {biogeochemistry,soil patterns, dissertation, dissertations, soil geomorphology, soil patterns, soil, nitrogen, theses, thesis, transect,soil patterns, transect,vegetation patterns}, author = {Rebecca A. Stein} } @conference {52269, title = {Vegetative and environmental response to chemical control of mesquite}, booktitle = {27th Annual Meeting, Society for Range Management}, year = {1974}, month = {1974}, pages = {41}, keywords = {chemical control, environmental response, mesquite, vegetative response}, author = {W. L. Gould and C.H. Herbel} } @mastersthesis {52440, title = {Vitamin A injections for range beef cows}, year = {1968}, note = {//USDA//NONE//}, month = {1968}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, abstract = {Intramuscular vitamin A injections of 1,000,000 or 2,000,000 I.U. in Hereford and Santa Gertrudis range cows did not significantly affect the weaning weights of calves in two experiments at the Jornada Experimental Range. Santa Gertrudis calves weighed significantly (P<.01) more than Hereford calves, 122 pounds more in 1966 and 90 pounds more in 1967. Sex of calf differences were significant only in 1966.}, keywords = {biochemistry, cattle nutrition, cattle, blood, cattle, nutrition, cattle,productivity, dissertation, dissertations, nutrition, cattle, theses, thesis}, author = {Abelardo Escobar Prieto} } @article {52476, title = {Vegetational changes on a semidesert grassland range from 1858 to 1963}, journal = {Ecological Monographs}, volume = {35}, number = {2}, year = {1965}, month = {1965}, pages = {139-164}, abstract = {

Extensive areas of the semidesert grassland of the Southwest are dominated by creosotebush [Larrea tridentata (DC) Coville], mesquite [Prosopis julifiora (Swartz) DC], and tarbush (Flourensia cernua DC). Mesquite occurs on 93,000,000 acres; creosotebush is present on 46,500,000; and tarbush occurs on 13,250,000 acres (Platt, 1959). Although the species are indigenous, they have invaded large areas in the past 100 years. Some areas invaded by tarbush still have a good understory of grass. However, loss of forage production occurs in early stages of mesquite invasion (Norris, 1950). In creosotebush-dominated areas, forage production is negligible (Gardner, 1951). The productivity of the rangeland greatly influences the economy of the Southwest. Therefore, it is important for the rancher to conserve and, where necessary, improve the range resource. Some knowledge of original vegetation conditions is essential in properly evaluating the potential of various sites. Much has been written about the semidesert grassland, including quotations from many early travelers. Some authors have based general assumptions on these quotations. However, the quotations are difficult to evaluate properly. In making their observations, many early travelers were influenced by the seasons and by their personal emotions. Furthermore, very few of the areas described by early travelers can actually be relocated for present-day comparisons. This study aims to show the degree of encroachment of brush on the study area and also the nature of the invasion on various soil types. Vegetation surveys of 1858, 1915, 1928, and 1963 were compared. Factors possibly responsible for the changes in vegetation were examined. This study was conducted on the Jornada Experimental Range, which is 23 mi north of Las Cruces, New Mexico.

}, keywords = {brush invasion, creosotebush, mesquite, monograph, semidesert grassland, tarbush, vegetation change}, doi = {10.2307/1948415}, url = {/files/bibliography/091.pdf}, author = {L.C. Buffington and C.H. Herbel} } @mastersthesis {52492, title = {Vegetational changes on a semidesert range from 1858 to 1963}, year = {1964}, note = {//USDA//NONE//}, month = {1964}, pages = {93}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The purpose of this study was to show the degree of encroachment of brush and also to study the nature of the invasion on the various soil types. Vegetation surveys of 1858, 1915, 1928, and 1963, formed the basis for comparisons. Factors possibly responsible for changes in vegetation were examined. The study was conducted on 144,475 acres of the Jornada Experimental Range, located 23 miles northeast of Las Cruces, New Mexico....Climatic change was not considered a major factor in brush invasion; however, periodic drought had some effect on brush invasion. Selective grazing by livestock also aided in the establishment of brush. Livestock are important in the dispersion of mesquite seeds. Early-day fires were not considered to be a factor in the maintenance of brush-free range, since no fires were reported by early travelers on the Jornada plain.}, keywords = {creosotebush, SEE , dissertation, dissertations, Flourensia,encroachment, grassland, shrub encroachment, history,vegetation changes, Larrea,encroachment, mesquite, SEE , Prosopis,encroachment, shrub, encroachment, succession, tarbush,SEE , theses, thesis, vegetation,shrub encroachment}, author = {L.C. Buffington} } @article {52537, title = {Vegetation of the creosotebush area of the Rio Grande Valley in New Mexico}, journal = {Ecological Monographs}, volume = {21}, year = {1951}, note = {//LOCAL//NONE//}, month = {1951}, pages = {379-403}, abstract = {The valley of the Rio Grande in New Mexico is bordered by a narrow belt of brush dominated mainly by creosotebush (Larrea divaricata) nearly as far north as the mouth of the Rio Puerco. This area is one of sparse vegetation and low rainfall. Par to the precipitation, however, falls as intense storms, resulting in flash floods from arroyos. These flash flows cause appreciable damage to highway and irrigation installations and to crops and agricultural land in the valley. The information presented in the present paper was collected during the course of investigations on arroyo control along the Rio Grande. It is derived from notes and measurements made in the shrub belt from Las Cruces, New Mexico, as far north as creosotebush is prominent in the vegetation, a distance of approximately 170 miles (Fig. 1).}, keywords = {arroyo, vegetation of, article, articles, cactus, distribution, Ephedra, Flourensia, plant associations, Flourensia,history, grass, distribution, history, Flourensia, history, Larrea, history,vegetation, journal, journals, Larrea community, Larrea, history, list,Larrea associated plants, Prosopis,plant associations, shrub, history, vegetation,Larrea community, washes, SEE }, author = {J. Gardner} } @article {52593, title = {Vegetation on gypsum soils of the Jornada plain, New Mexico}, journal = {Ecology}, volume = {19}, number = {4}, year = {1938}, month = {October 1938}, pages = {572-577}, abstract = {The small number of plant species and their sparse distribution on gypsum is a real problem on many ranges in the Southwest. Herrick ({\textquoteright}04) states that the great Jornada del Muerto plain is evidently underlain at no great depth by deposits of the Red Bed series, a gypsum-bearing formation extending from New Mexico into Texas, Oklahoma and Kansas. The White Sands in New Mexico, now mostly within a national monument, is a spectacular gypsum formation with both active and stabilized dunes containing from 96 to 98 percent hydrous calcium sulphate (Cockerell and Garcia, {\textquoteright}98; Coville and MacDougal, {\textquoteright}03; Macbride, {\textquoteright}05). Just a few miles west over the San Andres Mountains on the Jornada Experimental Range,{\textquoteright} several thousand acres are occupied by gypsum soils or by sandy soils underlain by gypsum at shallow depths. Regular observations of these two soil types from 1925 to 1934 with available climatic, vegetative, and grazing records constitute the basis for this report.}, keywords = {gypsum soils, Jornada del Muerto plain, observations, vegetation}, url = {/files/bibliography/041.pdf}, author = {R.S. Campbell and Campbell, I.F.} } @article {52595, title = {Vegetational density and composition of black grama type ranges as influenced by semideferred grazing}, year = {1938}, month = {August 1938}, pages = {2 }, publisher = {Research Notes Southwestern Forest and Range Experiment Station Note No.35}, abstract = {

It is not at all improbable that the first blades of grass that ever grew were in part grazed by some prehistoric plant-eating animal. All meat is a direct or indirect product of grass; therefore, grazing is not a new influence thrust suddenly into the environment of the plant but one that has existed throughout the ages. In the natural state, forces of nature operated to maintain a balance between animal life and the vegetation upon which it subsisted. No problems remained too long unsolved; no adjustments were too long delayed. If it had not been so, the ranges as we know them would have been eaten out of existence ages ago. To maintain abalance, the methods nature employed were direct and often harsh, consisting mainly of drought, reduction in birth rate, the predator and epidemic disease. With the accession of the stockmen to the ranges, a new influence was introduced which brought swift changes in the environment. Ranges were stocked with domestic animals, numbers of stock and their distribution were artificially regulated, the predator was practically eliminated, and disease was prevented. Drought alone remains uncontrolled and unpredictable. However, its force may be reduced and the impact eased by conservative stocking. The stockmen of the Southwest have originated many ingenious plans and systems of grazing in their efforts to minimize the ill effects of drought. The more promising of these practices have been incorporated into the designs of experiments conducted on the Jornada Experimental Range during the past quarter of a century.

}, keywords = {black grama composition, government publication, semideferred grazing, vegetation density}, url = {/files/bibliography/042.pdf}, author = {Canfield, R.H.} } @article {52615, title = {Values and limitations of clipped quadrats}, journal = {Ecology}, volume = {14}, number = {1}, year = {1933}, month = {January 1933}, pages = {35-39}, abstract = {

Many investigators have used the clipping method to obtain data representing the effects of varying intensities of harvesting grasses and other herbaceous vegetation. The work of Sarvis (\’23), Sampson and Malmsten (\’26), and Stapledon and Milton (\’30) on crop and pasture plants; and Harrison (\’31) on the maintenance of turf on golf courses illustrates the breadth of the field in which the method has been used. In range research, the yield and vigor of grasses under varying degrees of use have been the principal data desired to supplement actual grazing experiments. Many tests have shown the effects of various treatments upon the quality of the vegetation and also upon plant succession.

}, keywords = {clipping method, harvesting grasses, intensities, quadrats}, url = {/files/bibliography/024.pdf}, author = {Culley, M. J. and R.S. Campbell and Canfield, R.H.} } @article {52625, title = {Vegetative succession in the Prosopis sand dunes of southern New Mexico}, journal = {Ecology}, volume = {10}, number = {4}, year = {1929}, month = {October 1929}, pages = {392-398}, abstract = {

The Jornada Range Reserve, on which this study was made, was established in 1912 and has been conducted by the U.S. Forest Service as a range experiment station since 1915. It is a typical semi-desert range adjacent to the Rio Grande Valley in Dona Ana County, New Mexico, about 50 miles north of the Mexico boundary. There are about 145,000 acres (58,000 hectares) in the mesa portion of which approximately one-fourth is covered by the Prosopis sand dune type, consisting of low, evenly distributed dunes occupied principally by mesquite (Prosopis glandulosa Torr.), with " blow outs " (wind formed hollows) in between the dunes. The soils of the mesa are mostly Quaternary alluvium with older sands and gravels (Darton, {\textquoteright}22), and the Prosopis type is always found in the loose, wind-blown phase of the more sandy soils. The community is rather extensive in southern New Mexico, although it is not mentioned by Watson ({\textquoteright}12) in his description of the northern part of the state.

}, keywords = {Prosopis sand dunes, sandy soils, southern New Mexico, vegetative succession}, url = {/files/bibliography/017.pdf}, author = {R.S. Campbell} }