@article {JRN55387, title = {Diet selection of raramuri criollo and angus x hereford crossbred cattle in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {205}, year = {2022}, month = {7/4/2022}, pages = {104823}, abstract = {Strategies to help producers cope with unpredictable forage production associated with low and variable precipitation patterns on arid rangelands are needed, particularly if global warming trends continue as projected. One option is to identify cattle biotypes compatible with less productive shrubby landscapes. One such biotype is the Raramuri Criollo (RC) from the Copper Canyon of northern Mexico. This small-framed animal exhibits travelling behaviors that allow it to exploit vegetation at a greater distance from water, although it is unknown whether RC have dietary preferences that differ from European breeds typically raised in the southwestern U.S.A. We examined diet selection of RC vs. desert adapted Angus x Hereford (AH) crossbreds typical of the region using DNA metabarcoding to determine the proportion of plant species in fecal samples. Fecal samples were collected from 10 cows of each breed in two adjacent pastures during two seasons (growing and dormancy; four weeks per season) for three consecutive years. Dominant plant species in fecal samples of both cattle breeds were Atriplex canescens (four-wing saltbush), Hoffmannseggia glauca (hog potato), Hopia obtusa (vine mesquite), Setaria leucopila (plains bristlegrass), Sporobolus spp. (S. contractus, S. flexuosus, and S. giganteus), Pleuraphis mutica (tobosa), and Bouteloua eriopoda (black grama), which is consistent with previous studies in the region using different techniques for assessing dietary plant composition of other breeds of cattle. Only a few differences were detected between breeds. Compared to AH, fecal samples from RC tended to contain a higher proportion of mesquite and Yucca spp. (P < 0.07) and less Ephedra spp. (P < 0.06). The only grass species that differed between breeds was black grama (P < 0.05), with AH fecal samples containing about twice as much as RC cows (\~{}8\% vs. 4\%). This finding could have important implications for conservation of black grama in the Chihuahuan Desert.}, keywords = {beef cattle, diet selection, DNA metabarcoding, Raramuri Criollo}, doi = {10.1016/j.jaridenv.2022.104823}, url = {files/bibliography/22-016.pdf}, author = {Richard E. Estell and S. Nyamuryekung{\textquoteright}e and D. K. James and S. Spiegal and Andr{\'e}s F. Cibils and Amy L. Gonzalez and Matthew M. McIntosh and Kirsten B. Romig} } @article {JRN55394, title = {Degradation influences equilibrium and non-equilibrium dynamics in rangelands: Implications in resilience and stability}, journal = {Applied Vegetation Science}, year = {2022}, month = {06/2022}, pages = {e12670}, abstract = {Question: Plant communities are structured by both equilibrium and non-equilibrium dynamics, which interact at different spatio-temporal scales. The influence of external factors on internal regulation processes might depend on ecological state, and thus, on system resilience. We asked if well conserved (reference) states have higher resilience to external factors than degraded states, considering the greater capacity for self-regulation expected of reference states.}, keywords = {Alternative States Amplitude, Elasticity, grazing, Malleability, Rainfall Events, resistance, States and Transitions Model, thresholds}, doi = {10.1111/avsc.12670}, url = {files/bibliography/22-017.pdf}, author = {Dardo Rub{\'e}n L{\'o}pez and Laura Cavallero and Priscila Willems and Brandon T Bestelmeyer and M. A. Brizuela} } @conference {JRN55377, title = {Deep learning models for identifying cropland attributes from near surface cameras}, booktitle = {Biogeosciences}, year = {2022}, abstract = {The PhenoCam network is a global array of near-surface cameras used to track vegetation processes. With hundreds of cameras taking up to 48 photos a day this data stream has provided novel insight into many biological processes, yet PhenoCams in agricultural research have been underutilized. Here we use images from LTAR agricultural sites in the PhenoCam network to build a classification model for identifying cropland attributes such as crop type and phenological states. A variety of crops are used to generalize the states into 21 classes across 3 mutually exclusive categories, ranging from emergence to senescence. Other factors such as crop type and flooded or snow covered fields are also included. Deep learning models designed for image classification do not have a temporal component, so we use a hidden markov model in the classification post-processing to account for the temporal autocorrelation of daily camera time series. Initial classification F1 scores, a 0-1 accuracy metric, ranged from 0.83-0.85 with held out validation data, and were increased to 0.86-0.87 after the post-processing steps. Results show the feasibility of a daily, local scale dataset of field states and phenological stages with potential to be applied to other near-surface cameras for agroecosystem monitoring.}, author = {Shawn D. Taylor and Dawn M. Browning} } @proceedings {JRN55359, title = {Digital ranching as aspirational system for resilient ranching on Southwestern US rangelands}, year = {2022}, month = {2/8/2022}, abstract = {The Sustainable Southwest Beef Project led by New Mexico State University is strategically partnering with ranchers, researchers, extension specialist, educators and industry stakeholders to pioneer a Digital Ranching Platform for improving sustainability outcomes on ranches of the Southwestern US. The goals of the platform are to improve the operational efficiency of managing beef production systems for profitability, climate-resilience, and adaptive capacity. Ultimately, end-users will implement near realtime tracking and scouting of livestock across large pastures, rapid assessments of animal welfare, remote monitoring of rain gauge tipping buckets and tracking of water levels in cattle drinking troughs dispersed across the ranch. Another module is providing unobtrusive scoring of cattle body condition using support vector machine classifiers feeding on video imagery collected by automated infrared depth cameras. Methodologically, our approach fuses traditional statistics and smart analytics with novel dashboard tools to rapidly provide management indicators computed from streams of real-time data which are concurrently collected, logged and transmitted through a network of high throughput sensors, gateways routers and cloud computing services. The IoT infrastructure includes field sensors and accelerometer and GPS sensors on animals, and operates on a Long Range Wide Area Network (LoRa WAN) using solar or grid power and Ethernet, WiFi backhaul, or GSM communication. Our software engineering and IT team is developing a unified web-based server and dashboard application that facilitates the aggregation, visualization and retrieval of computed data, and configurations of sensors. Current analytics seek to enhance the harmonization (i.e. common feature representation) and curation of data using preprocessing, cleansing and normalization steps prior to implementing machine learning variants for classification and predictions objectives. Pilot case studies suggest several advantages of the system along with areas for potential improvement of existing sensors, network infrastructure and engineering, which may enhance future applications of the system on cooperating commercial ranches. }, keywords = {aspirational system, digital ranching, resilient ranching, Southwestern US rangelands}, author = {S. A. Utsumi and S. Nyamuryekung{\textquoteright}e and Matthew M. McIntosh and Andr{\'e}s F. Cibils and Richard E. Estell and S. Spiegal and G. Duff and Huiping Cao and LE Boucheron and H. Chen and Le, T. and Winkler, Z. and Rahman, S. and Qixu Gong and Andrew Cox and Craig Gifford and John P Ragosta and V. Gouvea and Carolina Brandani and Tony Waterhouse and J P Holland and Emile H. Elias and Skye Aney and Brandon T Bestelmeyer and Jean Steiner} } @proceedings {JRN55358, title = {Digital tools for sustainable ranching on Southwestern US rangelands}, year = {2022}, month = {2/8/2022}, abstract = {The Sustainable Southwest Beef Project is partnering with ranchers and stakeholders to develop a Digital Ranching Platform aimed at informing decision making of ranch-level management tasks and climate -resilient livestock systems. This aspirational management approach fuses traditional statistical and advanced data science with visualization dashboards to inform key indicators of animal welfare and ranch resources. The system collects large streams of real-time data, which is logged and transmitted through a network of high throughput sensors, gateways and cloud computing services. Internet of Things infrastructure includes field sensors and high throughput GPS sensors, and accelerometers mounted on animals, operating on a Long Range Wide Area Network (LoRaWAN) solar or grid powered and Ethernet, WiFi backhaul, or GSM communication. Software engineering and IT project components are focused on unifying a web-based dashboard and server application for visualization and retrieval of computed data and configuration of field devices and sensors. Utilities include improvements of operational efficiencies through near- to real-time tracking and scouting of livestock, rapid animal welfare assessments, remote monitoring of rain gauge tipping buckets and tracking of water level in cattle drinking troughs. Procedures seek to facilitate the harmonization (i.e. common feature representation) and curation of varying streams of data (i.e. erroneous sensor data and missing data points) prior to implementing machine learning for advance classification and prediction objectives. Future analytics will aim to merge patterns of animal data with insights on animal activity budgets, early warnings of breeding status, and faulty animal health or grazing performance. Unobtrusive scoring of cattle body condition is being collected using machine learning classifiers via high throughput video imagery of infrared depth cameras. Pilot case studies suggested important utilities of the system and have reveled several areas for improvement of existing sensor and network infrastructure and applications, which will be discussed in this symposium. }, keywords = {digital tools, rangelands, southwestern US, sustainable ranching}, author = {S. A. Utsumi and S. Nyamuryekung{\textquoteright}e and Matthew M. McIntosh and Andr{\'e}s F. Cibils and Richard E. Estell and S. Spiegal and G. Duff and Huiping Cao and LE Boucheron and H. Chen and Le, T. and Winkler, Z. and Rahman, Z. and Qixu Gong and Andrew Cox and Craig Gifford and John P Ragosta and Krohn, M. and V. Gouvea and Carolina Brandani and Tony Waterhouse and J P Holland and Emile H. Elias and Skye Aney and Brandon T Bestelmeyer and Jean Steiner} } @article {JRN55284, title = {Declines in rodent abundance and diversity track regional climate variability in North American drylands}, journal = {Global Change Biology}, volume = {27}, year = {2021}, month = {5/4/2021}, pages = {4005-4023}, abstract = {Regional long-term monitoring can enhance the detection of biodiversity declines associated with climate change, improving future projections by reducing reliance on space-for-time substitution and increasing scalability. Rodents are diverse and important consumers in drylands, regions defined by the scarcity of water that cover 45\% of Earth{\textquoteright}s land surface and face increasingly drier and more variable climates. We analyzed abundance data for 22 rodent species across grassland, shrubland, ecotone, and woodland ecosystems in the southwestern USA. Two time series (1995-2006, 2004-2013) coincided with phases of the Pacific Decadal Oscillation (PDO), which influences drought in southwestern North America. Regionally, rodent species diversity declined 20-35\%, with greater losses during the later time period. Abundance also declined regionally, but only during 2004-2013, with losses of 5\% of animals captured. During the first time series (wetter climate), plant productivity outranked climate variables as the best regional predictor of rodent abundance for 70\% of taxa, whereas during the second period (drier climate), climate best explained variation in abundance for 60\% of taxa. Temporal dynamics in diversity and abundance differed spatially among ecosystems, with the largest declines in woodlands and shrublands of central New Mexico and Colorado. Which species were winners or losers under increasing drought and amplified interannual variability in drought depended on ecosystem type and the phase of the PDO. Fewer taxa were significant winners (18\%) than losers (30\%) under drought, but the identities of winners and losers differed among ecosystems for 70\% of taxa. Our results suggest that the sensitivities of rodent species to climate contributed to regional declines in diversity and abundance during 1995 - 2013. Whether these changes portend future declines in drought-sensitive consumers in the southwestern USA will depend on the climate during the next major PDO cycle.}, keywords = {biodiversity, climate change, Dipodomys, Onychomys, Peromyscus, small mammal, Standardized Precipitation Evapotranspiration Index}, doi = {10.1111/gcb.15672}, url = {files/bibliography/21-024.pdf}, author = {Pablo A. C{\'a}rdenas and Erica M. Christensen and Morgan Ernest and David C. Lightfoot and Robert L. Schooley and Paul Stapp and J.A. Rudgers} } @proceedings {JRN55323, title = {Data management in excel and R using national ecological observatory network{\textquoteright}s (NEON) small mammal data}, year = {2021}, month = {01/13/2021}, abstract = {Undergraduate STEM students are graduating into professions that require them to manage and work with data at many points of a data management life cycle. Within ecology, students are presented not only with many opportunities to collect data themselves, but increasingly to access and use public data collected by others. This activity introduces the basic concept of data management, spreadsheet management, and metadata to allow meaningful~data analysis. The accompanying presentation materials mention the importance of considering long-term data storage and data analysis using public data.}, doi = {10.25334/Q4XH5S}, author = {Marguerite Mauritz and Sarah McCord} } @conference {JRN55296, title = {Dam-offspring pairing using proximity loggers fitted on Raramuri Criollo cows and calves grazing desert rangeland}, booktitle = {Society for Range Management Meeting Abstracts}, year = {2021}, month = {2/15/2021}, abstract = {Proximity loggers are sensors that transmit and receive UHF radio signals and have been used to investigate social behavior in livestock. Previous studies that used these devices found that cow-calf contact events occur throughout the day at intervals that likely reflect nursing events. We determined the feasibility of utilizing proximity data to correctly identify cow-calf pairs within a herd of Raramuri Criollo cattle grazing Chihuahuan Desert rangeland. The study was conducted at the Jornada Experimental Range on a 4300 ha pasture that was lightly stocked (216 ha/AUM). Ten proximity loggers were deployed on five cow-calf pairs during the summer/fall of 2015 and 2016 (21days/deployment). All calves were <2 weeks old at the onset of the study. The loggers recorded time of initiation and duration of contacts any time another logger was within a one-meter radius of the subject. We used one-way analysis of variance to analyze daily contact duration patterns between each collared cow and all collared calves in the herd. Except for one cow in the herd (Dam25), all dams spent significantly more time within 1 m of their offspring vs. other collared calves in the herd (P<0.05). Proximity logger data yielded cow-calf pairings that were 100\% accurate. Newer less expensive technology such as Bluetooth-enabled wearable livestock sensors offers opportunities to track cow-calf contact patterns in real time and could help ranchers identify dam-offspring pairs using the analytical approach followed in this study. This approach could be particularly useful for rangeland cow-calf producers that run seedstock operations.}, author = {Simpson, C. and S. Nyamuryekung{\textquoteright}e and Andr{\'e}s F. Cibils and Richard E. Estell and Amy L. Gonzalez and Matthew M. McIntosh and S. Spiegal} } @article {JRN55339, title = {Data to explore circular manureshed management in beef supply chains of the United States and western Canada}, year = {2021}, publisher = {EDI Data Portal}, abstract = {Circular management of beef supply chains holds great promise for improving sustainability from grazing agroecosystem to dinner plate. In the United States and Canada, one approach to circularity entails transporting manure nutrients from cattle produced in feedlots back to the grazing agroecosystems where they originated to enrich haylands for further grazing cattle production. We provide data to assess this strategy centered around three grazing agroecosystems: Florida, New Mexico, and the provincial assemblage of Manitoba, Saskatchewan, Alberta, British Columbia. We describe four datasets that can be used to estimate the potential nutrient utilization of hay fed to grazing cattle in the three grazing agroecosystems and the magnitudes of feedlot manure nutrients available for transport back to them. We found that although biogeography and management differ among the three grazing agroecosystems, the hay allocated for grazing cattle represented approximately 65\% of the total harvested hay produced per agroecosystem after accounting for harvest losses, and that on average all three areas exported about 450,000 cattle annually for feedlot, pasture, and slaughter to states across the US. Although we highlight only three grazingland settings, our approach relies on methods that could ultimately be scaled nationally and internationally, with applicability to other animal industries for which circular management is an aspiration for sustainability outcomes. }, keywords = {beef supply chains, circular, data, explore, management, manureshed, United States, western Canada}, doi = {10.6073/pasta/8b73fec5b84eb0313a1891e4ee77cba2}, author = {S. Spiegal and Jo{\~a}o M.B. Vendramini and S. Bittman and Maria Silveira and Craig Gifford and C. A. Rotz and John P Ragosta and Peter J. A. Kleinman} } @article {JRN55213, title = {A Decision Support System for Incorporating Land Potential Information in the Evaluation of Restoration Outcomes}, journal = {Ecological Restoration}, volume = {38}, year = {2020}, month = {06/2020}, pages = {94-104}, abstract = {Regular monitoring and evaluation of rangeland restoration outcomes is necessary for accountability, adaptive management throughout the restoration process, and informing future project design. Monitoring and evaluating restoration outcomes can help restoration practitioners and land managers identify restoration successes and failures. Collecting information about differences in potential vegetation productivity in restored areas can help understand and predict these different outcomes. Here, we provide a decision-tree based framework for designing monitoring programs for restoration projects. We emphasize the need to collect land potential information to help evaluate and contextualize restoration outcomes. We then highlight a mobile phone application that can be used to collect basic land potential information with minimal time and training requirements. }, keywords = {LandPKS, monitoring, restoration success, retrospective assessment}, doi = {10.3368/er.38.2.94}, url = {files/bibliography/20-020.pdf}, author = {D.W. Kimiti and Amy Ganguli and Jeffrey E. Herrick and Jason W. Karl and C. Donovan Bailey} } @conference {JRN55239, title = {A data commons approach can help span scales and stakeholders to support ecosystem conservation and land use}, booktitle = {Ecological Society of America}, year = {2020}, month = {02/2020}, address = {Salt Lake City, Utah}, abstract = {Background: Drivers of ecosystem changes include climate change, changing land uses, land management, and invasive species. Research efforts are underway to understand the impacts these drives on ecosystem services and agricultural production systems. At the same time, land managers seek to understand these interactions and implement conservation practices to ensure that management objectives are being met. To address these research and management needs, scientists and land managers have developed a range of disconnected data collection and monitoring initiatives. A strength of these initiatives has been the adoption of a suite of standardized vegetation and soil monitoring methods. These methods measure vegetation cover and structure, as well as soil horizon characteristics across dryland ecosystems from the Chihuahan Desert to the Arctic Tundra to the Mongolian Steppe. Yet, using this multi-scale ecosystem information can be challenging as it is difficult to locate and access these standardized data, ensure that they are trustworthy, and connect them to models and analytical tools. Here we present the Landscape Data Commons, which provides common rangeland datasets, standardized analysis tools and linkages to models that can integrate and add value to the data. The Landscape Data Commons provides a capability to deliver monitoring-derived information to benefit research, policy and land management across the United States and internationally. Methods:Cumulatively, across research institutions, state and federal land management agencies, and non-profit organizations over 60,000 rangeland monitoring locations have been sampled since 1995 in the western US. In aggregate, these data provide a unique and underutilized opportunity to understand rangeland change and ecosystem patterns across physiographic gradients as well as land use and land ownership. In this talk, we will discuss the novel cyberinfrastructure developments which have facilitated the aggregation of these monitoring data. We will also present how the Landscape Data Commons is being leveraged to understand ecosystem change at local and regional scales in combination with wind erosion models, decision frameworks, citizen science and sensor big datasets. We provide community and landscape scale examples of how the Landscape Data Commons is helping to elucidate previously unquantified patterns in soil erosion, invasive species spread to inform land management decisions and further research into ecological dynamics. We will conclude by discussing how the principles of the Landscape Data Commons can be applied to address grand challenges in ecosystem science and management. Paper number $\#$82161.}, author = {Sarah McCord and Nicholas Webb and Kristopher Bonefont and Rachel Burke and Brandon Edwards and Brandon T Bestelmeyer and Jeffrey E. Herrick} } @article {JRN55191, title = {Do Young Calves Influence Movement Patterns of Nursing Raramuri Criollo Cows on Rangeland?}, journal = {Rangeland Ecology and Management}, volume = {73}, year = {2020}, month = {01/01/2020}, pages = {84-92}, abstract = {

We compared movement patterns of nursing versus non-nursing cows and characterized cow-calf proximity patterns over 2 years in two herds of Raramuri Criollo (RC) cattle that grazed either desert rangeland of southern New Mexico, United States, or woodlands of west-central Chihuahua, Mexico. At each site, 9{\textendash}14 randomly selected mature cows were fitted with Global Positioning System (GPS) collars configured to record animal position at 5-min intervals. Four to five GPS-collared nursing cows and their calves were also fitted with proximity loggers that recorded initiation time and duration of dam-calf contact events (\< 1 m logger-to-logger distance). All calves were \< 2 wk old at the onset of the study. Collared animals grazed with a herd of 30 and 35 cows at the NM site and with 68 and 87 cows at the Chihuahua site in 2015 and 2016, respectively. Non-nursing RC cows exhibited straighter travel paths and explored larger daily areas than their nursing counterparts. However, nursing and non-nursing RC cows in this study traveled similar distances each day, moved at comparable velocities, spent similar amounts of time close to drinkers, and did not differ in daily time spent grazing, resting, or traveling. A higher number of cow-calf contact events occurred during day versus nighttime hours, but total day versus night contact time was similar. As calves became older, the number of both day and nighttime contact events, as well as dam-offspring contact time, decreased significantly. Relative to their calves, dams explored larger areas of the pasture each day; however, cow-calf contact events occurred throughout the entire area grazed by the dams including areas surrounding the drinkers. Cow-calf interactions of RC cows resembled those of a strong follower regardless of the grazing environment and differed from previously reported mother-offspring relations in mainstream British beef cattle breeds.

}, doi = {10.1016/j.rama.2019.08.015}, url = {files/bibliography/20-008.pdf}, author = {S. Nyamuryekung{\textquoteright}e and Andr{\'e}s F. Cibils and Richard E. Estell and D. VanLeeuwen and Caitriana Steele and Roacho Estrada, O. and Felipe A. Rodr{\'\i}g Almeida and Amy L. Gonzalez and S. Spiegal} } @article {JRN55198, title = {Deciphering the past to inform the future: preparing for the next ({\textquotedblleft}really big{\textquotedblright}) extreme event}, journal = {Frontiers in Ecology and the Environment}, year = {2020}, month = {04/2020}, pages = {10.1002/fee.2194}, abstract = {

Climate change will bring more extremes in temperature and precipitation that will impact productivity and ecosystem resilience throughout agroecosystems worldwide. Historical events can be used to identify drivers that impact future events. A\  catastrophic drought in the US in the 1930s resulted in an abrupt boundary between areas severely impacted by the Dust Bowl and areas that were less severely affected. Historical primary production data confirmed the location of this boundary at the border between two\ states (Nebraska and Iowa). Local drivers of weather and soils explained production responses across the boundary before and after the drought (1926{\textendash}1948). During the drought, however, features at the landscape scale (soil properties and wind velocities) and regional scale (the Missouri River, its floodplain, and the nearby Loess Hills) explained most of the observed variance in primary production. The impact of future extreme events may be affected by land surface properties that either accentuate or ameliorate the effects of these events. Consideration of large-scale geomorphic processes may be necessary to interpret and manage for catastrophic events.

}, keywords = {agroecosystems, climate change, dust, dust bowl, future, historical, large-scale, regional-scale}, doi = {10.1002/fee.2194}, url = {bibliography/20-010.pdf}, author = {Debra C. Peters and N. Dylan Burruss and Gregory S. Okin and J. Hatfield and Stacey L P Scroggs and Haitao Huang and Colby Brungard and Jin Yao} } @article {JRN55309, title = {Digital soil mapping to support California ecological site development}, volume = {90}, year = {2020}, pages = {27-28}, chapter = {Government Publication/Report}, abstract = {In late January 2020, soil and rangeland scientists from the Agricultural Research Service (ARS) joined conservation staff from the Santa Lucia Conservancy in Carmel, California, to describe and sample grassland soils of the Central California Coastal Range. Recently, ARS scientists entered into a partnership with the Santa Lucia Conservancy, which stewards an 18,000-acre preserve of protected natural lands, to provide expertise and advice on rangeland ecology, develop state-and transition models, and analyze grazing and landscape data to evaluate grassland and rangeland response to the conservancy{\textquoteright}s targeted grazing program. ARS cooperators used digital soil mapping techniques to sample and map soils classes across the preserve{\textquoteright}s grasslands. Prior to sampling, we applied the conditioned Latin Hypercube Sampling (cLHS) method, a random stratified procedure that chooses sampling locations based on a suite of soil-forming environmental variables. Using cLHS with a sampling number optimization algorithm and a cost constrained implementation, we identified 41 soil and vegetation sampling sites across the preserve{\textquoteright}s coastal prairie and oak savanna landscapes. Many stakeholders and cooperators joined the soil and vegetation field sampling, including scientists from NRCS (Genevieve Landucci, Templeton, California), Point Blue Conservation Science (Chelsea Carey, Petaluma, California), the California Conservation Corps, Americorps Watershed Stewards Program, and the Santa Lucia Conservancy. The next step is to analyze chemical and physical properties of the soil samples and conduct analysis of the conservancy{\textquoteright}s vegetation and grazing data. Our collaboration helps support the Santa Lucia Conservancy{\textquoteright}s science-based mission to enable data-driven assessments of grassland and rangeland conditions, including the development of best management practices that promote native herbaceous plants, reduce noxious weeds, control non-native vegetation, and prevent brush encroachment.}, author = {S. W. Salley} } @proceedings {JRN55189, title = {Defining thresholds for wind erosion in desert rangeland STMs}, volume = {Session 9}, year = {2020}, month = {02/16/2020}, address = {Denver, CO}, abstract = {

Within the US, conventional understanding has been that most erosion is occurring in the Great Plains, but our knowledge about the extent and severity of rangeland wind erosion has been limited by monitoring and modeling technologies. Data from air quality monitoring programs like IMPROVE show there was a 75\% increase in spingtime fine dust concentrations between 2000 and 2014 across the western states, but we still have a limited understanding of where, when and how much erosion is occurring. Importantly, few tools are available to help managers assess why wind erosion is occurring in responses to land use and management. This information is needed to identify appropriate conservation practices. As a consequence, wind erosion isn{\textquoteright}t typically considered in assessments of land resource condition despite its importance for plant community dynamics, agroecosystem resilience, regional air quality and climate. To address this problem we developed an Aeolian EROsion (AERO) model designed to run on standardized soil and vegetation monitoring datasets that are collected across the west. AERO is a physically-based model that requires inputs of surface soil texture, bare soil fraction, canopy gap size distribution, average canopy height and time-series or probability distribution of wind speeds for a plot location. By leveraging large standardized monitoring datasets, like those collected by the NRCS NRI and BLM AIM programs, AERO can be used to develop an understanding of potential sediment transport rates and dust emissions across rangelands as influenced by soil properties and the kinds, amounts, proportions and structure of different vegetation species. From AERO applications, we are developing approaches based on the Ecological Land Resource Hierarchy to understand the range of potential wind erosion for different land units at different spatial scales. Our work is then exploring approaches to establish benchmarks based on structural and functional thresholds of concern that enable managers to evaluate how wind erosion responds to changes in the kinds, amounts and proportions of vegetation within ecological sites. By using AERO to integrate the indicators of vegetation structure, the model can also be used to identify functional thresholds for wind erosion and assess whether these thresholds can be generalized across ecological sites and states to inform management at broader spatial scales.

}, keywords = {desert rangeland STMs, thresholds, wind erosion}, author = {Nicholas Webb and Brandon Edwards and Rachel Burke and Sarah McCord and Justin Van Zee and Ericha Courtright and Brad Cooper} } @article {JRN55141, title = {Drought suppresses soil predators and promotes root herbivores in mesic, but not in xeric grasslands}, journal = {Proceedings of the National Academy of Sciences}, volume = {116}, year = {2019}, pages = {12883{\textendash}12888}, abstract = {

Precipitation changes among years and locations along gradients of mean annual precipitation (MAP). The way those changes interact and affect populations of soil organisms from arid to moist environments remains unknown. Temporal and spatial changes in precipitation could lead to shifts in functional composition of soil communities that are involved in key aspects of ecosystem functioning such as ecosystem primary production and carbon cycling. We experimentally reduced and increased growing-season precipitation for 2 y in field plots at arid, semiarid, and mesic grasslands to investigate temporal and spatial precipitation controls on the abundance and community functional composition of soil nematodes, a hyper-abundant and functionally diverse metazoan in terrestrial ecosystems. We found that total nematode abundance decreased with greater growing-season precipitation following increases in the abundance of predaceous nematodes that consumed and limited the abundance of nematodes lower in the trophic structure, including root feeders. The magnitude of these nematode responses to temporal changes in precipitation increased along the spatial gradient of long-term MAP, and significant effects only occurred at the mesic site. Contrary to the temporal pattern, nematode abundance increased with greater long-term MAP along the spatial gradient from arid to mesic grasslands. The projected increase in the frequency of extreme dry years in mesic grasslands will therefore weaken predation pressure belowground and increase populations of root-feeding nematodes, potentially leading to higher levels of plant infestation and plant damage that would exacerbate the negative effect of drought on ecosystem primary production and C cycling.

}, issn = {0027-8424}, doi = {10.1073/pnas.1900572116}, url = {files/bibliography/Francoetal2019.pdf}, author = {A. C. Franco and Laureano A. Gherardi and Cecilia M. de Tomasel and Andriuzzi, Walter S. and Ankrom, Katharine E. and Shaw, E. Ashley and Bach, Elizabeth M. and O. E. Sala and D.H. Wall} } @article {JRN55067, title = {Dust emission from crusted surfaces: Insights from field measurements and modelling}, journal = {Aeolian Research}, volume = {40}, year = {2019}, month = {06/2019}, pages = {1-14}, chapter = {1}, abstract = {

Crusted surfaces can be major sources of mineral dust emission. Quantitative understanding of dust emission from crusted surfaces is limited, because (1) theories on dust emission are not well tested for such surfaces; and (2) modelling is hampered by a lack of input data sufficient to describe the surface conditions. Combining detailed field measurements with physics-based numerical modelling, we present new insights into dust emission from crusted surfaces. Our measurements confirm that crust erodibility and dust-emission intensity can increase or decrease after previous erosion events. To support interpretation of the measurements and to test the applicability of a state-of-the-art parameterisation to simulate dust emission from crusted surfaces, we apply the dust emission scheme of Shao (2004). Saltation flux, which is input to the scheme, is approximated using the parameterisation of Kawamura (1964) and a scaling factor obtained from observations. Limitations of this approach are discussed. Our results show that the dust emission scheme is suitable to estimate dust emission from crusted surfaces if accurate input data and parameters describing the soil-surface condition are provided. The parameters were optimized for each dust event to achieve a best estimate. The variation of the resulting parameter values confirms the observed variability of dust-emission efficiency between the events and provides further evidence that it was caused by variations in crust erodibility. Our study demonstrates that available physics-based dust-emission parameterisations are able to simulate dust emissions under complicated conditions, but also that refined information on the soil-surface conditions are needed as input to the schemes.

}, doi = {doi.org/10.1016/j.aeolia.2019.05.001}, url = {files/bibliography/19-008.pdf}, author = {Martina Klose and Thomas E. Gill and Vicken Etyemezian and Nikolich, George and Ghodsi Zadeh, Zahra and Nicholas Webb and Scott Van Pelt} } @article {JRN55131, title = {Digital mapping of ecological land units using a nationally scalable modeling framework}, journal = {Soil Science Society of America Journal}, volume = {83}, year = {2019}, month = {06/2019}, pages = {666-686}, chapter = {666}, abstract = {

Ecological site descriptions (ESDs) and associated state-and-transition models (STMs) provide a nationally consistent classification and information system for defining ecological land units for management applications in the U.S. Current spatial representations of ESDs, however, occur via soil mapping and are therefore confined to the spatial resolution used to map soils within a survey area. \ Land management decisions occur across a range of spatial scales and therefore require ecological information that spans similar scales. Digital mapping provides an approach for optimizing the spatial scale of modeling products to best serve decision makers and have the greatest impact in addressing land management concerns. Here we present a spatial modeling framework for mapping ecological sites using machine learning algorithms, soil survey field observations, soil survey geographic databases, ecological site data, and a suite of remote sensing-based spatial covariates (e.g., hyper-temporal remote sensing, terrain attributes, climate data, land-cover, lithology). Based upon the theoretical association between ecological sites and landscape biophysical properties, we hypothesized that the spatial distribution of ecological sites could be predicted using readily available geospatial data. This modeling approach was tested at two study areas within the western U.S., representing 6.1 million ha on the Colorado Plateau and 7.5 million ha within the Chihuahuan Desert. Results show our approach was effective in mapping grouped ecological site classes (ESGs), with a 70\% correct classification based on 1,405 point observations across 8 expertly-defined ESG classes in the Colorado Plateau and a 79\% correct classification based on 2,589 point observations across 9 expertly-defined ESG classes in the Chihuahuan Desert. National coverage of the training and covariate data used in this study provides opportunities for a consistent national-scale mapping effort of ecological sites.

}, doi = {10.2136/sssaj2018.09.0346}, url = {files/bibliography/19-012.pdf}, author = {Jonathan Maynard and Travis Nauman and S. W. Salley and Brandon T Bestelmeyer and Danielle Duni and Curtis Talbot and Joel R. Brown} } @article {JRN55130, title = {Data jams: Promoting data literacy and science engagement while encouraging creativity}, journal = {Science Teacher}, year = {2018}, month = {08/2018}, pages = {48-53}, chapter = {48}, abstract = {

Thousands of students around the country have participated in activities using the Data Jam model, creating poetry, songs, videos, or sculpture to improve their data literacy, gain knowledge of local science research, and creatively express their findings. This article introduces the Data Jam model and how teachers can use it in classroom or after-school settings, supported by vignettes of student projects and feedback from teachers and students. Data is the lens through which we increasingly view our world, and scientific data literacy skills are a key component of the Next Generation Science Standards{\textquoteright} (NGSS) science and engineering practices (Berkowitz, Ford, and Brewer 2005). Understanding how to engage with data, however, can be challenging for students. Most have limited experience with authentic scientific data sets, and find them complex and intimidating. Clear, creative communication is crucial to helping students (and the general public) understand data and scientific findings. Interest in creative and artistic science communication tools has increased, as evidenced by the proliferation of projects such as the SciShow YouTube video series and the Dance Your Ph.D. contest from the American Association for the Advancement of Science (see {\textquotedblleft}On the web.{\textquotedblright}) Inspired by this movement, four science education organizations have developed the Data Jam model to engage high school students in learning about ecological research while igniting their creativity. Students analyze and interpret environmental data sets, then communicate their findings through a creative medium. This approach also supports the STEM to STEAM (science, technology, engineering, art, and math) movement, which was initially championed by the Rhode Island School of Design as a way to capitalize on the creative synergy between art and scientific disciplines.

}, url = {files/bibliography/18-027.pdf}, author = {Michelle Forster and Stephanie Bestelmeyer and Noelia Baez-Rodriguez and Alan Berkowitz and Bess Caplan and Rhea Esposito and Grace, Elizabeth and Steven McGee} } @article {JRN55005, title = {Digital soil mapping for predicting and managing fire in rangelands}, journal = {Fire Ecology}, year = {2018}, month = {12/2018}, pages = {1-12}, chapter = {1}, abstract = {

Background: Soil properties have important effects on fire occurrence and spread, but soils are often overlooked in
fire prediction models. Quantifying soil-fire linkages is limited by information in conventional soil maps, but digital
soil mapping products (e.g., detailed soil property maps) could improve both wildfire prediction models and post-fire
management decisions.
Results: Of our estimated 3.7 Mkm2 of rangeland in the continental US and Alaska, an average of 38 000 km2 burned
per year between 2008 and 2017. To highlight the role of soils in fire ecology, we present 1) a conceptual framework
explaining why soil information can be useful for fire models, 2) a comprehensive suite of literature examples that used
soil property information in traditional soil survey for predicting wildfire, and 3) specific examples of how more detailed
soil information can be applied for pre- and post-fire decisions.
Conclusions: Digital soil mapping can improve fire prediction models and inform post-fire management decisions

}, keywords = {digital soil mapping, fire effects, grasslands, shrublands, soil moisture, spatial modeling, wildfire}, doi = {doi.org/10.1186/s42408-018-0018-4}, url = {files/bibliography/19-006.pdf}, author = {Matthew Levi and Brandon T Bestelmeyer} } @conference {JRN54940, title = {Developing an integrated knowledge landscape map using a trans-disciplinary approach}, booktitle = {LTER All Scientists Meeting}, year = {2018}, month = {10/2018}, address = {Pacific Grove, California}, abstract = {

Our goal is to develop an operational trans-disciplinary approach to complex landscapes that facilitates integration of large and diverse types of data and knowledge to: (1) reduce the high spatial heterogeneity in sampling across heterogeneous landscapes and fill data/knowledge gaps for underrepresented locations; (2) characterize the non-stationarity of environmental drivers and ascertain the extent to which knowledge of the past can, or cannot, inform the future; and (3) inform land managers and others in prioritizing locations. We illustrate the utility of our approach to extend process-based understanding of ANPP at intensively studied locations to dynamics of ANPP at other under-represented locations, and to predict spatial variability in ANPP across the landscape.

}, author = {Debra C. Peters and Brandon T Bestelmeyer and Gregory S. Okin and O. E. Sala and Enrique Vivoni and Steven R. Archer and Colby Brungard and Jeffrey E. Herrick and Niall Hanan} } @proceedings {JRN54867, title = {Developing regionally specific grazing practices to promote production, profitability, and environmental quality}, volume = {January 28-February 2, 2018}, year = {2018}, month = {01/28/2018}, publisher = {Society for Range Management Meeting Proceedings}, address = {Sparks, Nevada}, abstract = {

Rangelands are valued for their capacity to provide diverse suites of ecosystem services, from food production to carbon storage to biological diversity. Although rangelands worldwide share common characteristics, differences among biogeographic regions result in differences in the types of opportunities for ranchers and other rangeland managers to preserve and enhance multiple services. For instance, opportunities to use grazing to promote biodiversity while meeting growing global demand for beef vary among the rangelands of Mediterranean California, the Chihuahuan Desert, and the Great Plains, USA. The drivers of these regional differences are biophysical, social, and economic. Understanding the drivers and their interactions can improve planning for regionally specific grazing practices, land uses, funding programs, and scientific research that optimize the provision of multiple services from U.S. rangelands. We present a model identifying the drivers that differentiate regional opportunities, and use it to compare grazing management options in Mediterranean California with those in other rangeland regions across the United States.

}, author = {S. Spiegal and Brandon T Bestelmeyer and Joel R. Brown} } @proceedings {JRN54858, title = {DIMA.Tools: An R package for working with the database for inventory, monitoring, and assessment}, volume = {January 28-February 2, 2018}, year = {2018}, month = {01/28/2018}, publisher = {Society for Range Management Meeting Proceedings}, address = {Reno, NV}, abstract = {

The Database for Inventory, Monitoring, and Assessment (DIMA) is a Microsoft Access database used to collect, store and summarize monitoring data. This database is used by both local and national monitoring efforts within the National Park Service, the Forest Service, the Bureau of Land Management, Agricultural Research Service, non-profit organizations, and land management agencies globally, including Mongolia. The Access format permits long-term storage of large datasets and enables electronic data capture in the field, sophisticated error checking procedures, and a graphical user interface, however analysis of large amounts of data in one or more DIMAs is difficult. Therefore, further analysis and the production of quality monitoring information often requires interacting with DIMA via other software interfaces such as R.Here we present an package for R, dima.tools, containing functions which simplify direct user access to raw data tables within DIMAs and combining data from multiple DIMAs. Additionally, common data manipulation functions are available in the package for low-level tasks like tidying data and joining data to metadata as well as higher-level functions for tasks like producing standard indicators and quality assurance and quality control checks. Together, these provide a reproducible framework for users to compute their own custom indicators and to complete complex analyses using other functions and packages in R.

}, author = {Nelson Stauffer and Sarah McCord} } @conference {JRN54806, title = {Drawing a representative sample from the NCSS soil database: Building blocks for the national wind erosion network}, booktitle = {ASA-CSSA-SSSA Annual Meeting Abstracts}, year = {2017}, month = {10/2017}, publisher = {ASA-CSSA-SSSA Annual Meeting Abstracts}, organization = {ASA-CSSA-SSSA Annual Meeting Abstracts}, address = {Tampa, Florida}, abstract = {

Developing national wind erosion models for the continental United States requires a comprehensive spatial representation of continuous soil particle size distributions (PSD) for model input. While the current coverage of soil survey is nearly complete, the most detailed particle size classes have categorical of sand, silt, and clay. The National Cooperative Soil Survey (NCSS) database has laboratory data for over 21,000 pedons, but continuous PSDs are not available. Existing soil maps provide the link between NCSS pedon data enable the transfer of detailed laboratory data to spatial representations. Extracting a representative sample from the existing NCSS data for expensive, detailed PSD analysis requires the ability to capture maximum variance with the minimal number of samples. We performed a sensitivity analysis of sample selection to compare the effect of different soil and geographic features on representation of the larger database. A conditioned Latin Hypercube sample design was used to select samples based on their feature space and compared to simple random samples. Comparisons of extracted sample datasets showed little difference for \ bulk density, water content (field capacity, wilting point, plant available water) and sand fractions. Stronger differences emerged with fewer samples in the dataset. Spatial coverage of all samples effectively represented the geographic coverage of the continental US. This exercise provides insight for how distributions of the PSDs may vary by selection method and also illustrates the ability of different sample sizes for representing the larger database. Our work will inform future sample selection from existing soil databases for modeling at continental scales.

}, author = {Matthew Levi and Nicholas Webb} } @conference {JRN54646, title = {Is desertification a dirty word?}, booktitle = {Ecological Society of America}, year = {2016}, month = {08/2016}, publisher = {Ecological Society of America Abstracts}, organization = {Ecological Society of America Abstracts}, address = {Fort Lauderdale}, abstract = {

Desertification refers to land degradation in drylands. The term is widely used in ecology and is the basis for a United Nations convention. At best, it is a vague term. At worst, it has been referred to as the {\textquotedblleft}lie of the land{\textquotedblright} and a tool by which powerful actors disenfranchise less powerful ones. I argue that reference to specific state change processes can promote solutions. Desertification in reference to ecological processes should be stricken from scientific discourse. Nonetheless, like other dirty words, {\textquotedblleft}desertification{\textquotedblright} draws attention to critical problems.

}, author = {Brandon T Bestelmeyer} } @article {JRN54630, title = {Direct effects dominate responses to climate perturbations in grassland plant communities}, journal = {Nature Communications}, year = {2016}, pages = {1-10}, abstract = {

Theory predicts that strong indirect effects of environmental change will impact communities when niche differences between competitors are small and variation in the direct effects experienced by competitors is large, but empirical tests are lacking. Here we estimate negative frequency dependence, a proxy for niche differences, and quantify the direct and indirect effects of climate change on each species. Consistent with theory, in four of five communities indirect effects are strongest for species showing weak negative frequency dependence. Indirect effects are also stronger in communities where there is greater variation in direct effects. Overall responses to climate perturbations are driven primarily by direct effects, suggesting that single species models may be adequate for forecasting the impacts of climate change in these communities.

}, keywords = {black grama grass, Bouteloua eripoda, chart quadrat data, climate change, climate perturbations, environmental change, grass communities, model}, doi = {10.1038/ncomms11766}, url = {/files/bibliography/16-016.pdf}, author = {Chu, Chengjin and Kleinhesselink, Andrew R. and Kris Havstad and M.P. McClaran and Debra C. Peters and Vermeire, Lance T. and Wei, Haiyan and Peter B. Adler} } @conference {JRN54609, title = {Do climate model predictions agree with long-term precipitation trends in the arid southwestern United States?}, booktitle = {American Geophysical Union}, year = {2016}, month = {12/2016}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {
Researchers evaluating climate projections across southwestern North America observed a decreasing precipitation trend. Aridification was most pronounced in the cold (non-monsoonal) season, whereas downward trends in precipitation were smaller in the warm (monsoonal) season. In this region, based upon a multimodel mean of 20 Coupled Model Intercomparison Project 5 models using a business-as-usual (Representative Concentration Pathway 8.5) trajectory, midcentury precipitation is projected to increase slightly during the monsoonal time period (July-September; 6\%) and decrease slightly during the remainder of the year (October-June; -4\%). We use observed long-term (1915-2015) monthly precipitation records from 16 weather stations to investigate how well measured trends corroborate climate model predictions during the monsoonal and non-monsoonal timeframe. Running trend analysis using the Mann-Kendall test for 15 to 101 year moving windows reveals that half the stations showed significant (p=0.1), albeit small, increasing trends based on the longest term record. Trends based on shorter-term records reveal a period of significant precipitation decline at all stations representing the 1950s drought. Trends from 1930 to 2015 reveal significant annual, monsoonal and non-monsoonal increases in precipitation (Fig 1). The 1960 to 2015 time window shows no significant precipitation trends. The more recent time window (1980 to 2015) shows a slight, but not significant, increase in monsoonal precipitation and a larger, significant decline in non-monsoonal precipitation. GCM precipitation projections are consistent with more recent trends for the region. Running trends from the most recent time window (mid-1990s to 2015) at all stations show increasing monsoonal precipitation and decreasing Oct-Jun precipitation, with significant trends at 6 of 16 stations. Running trend analysis revealed that the long-term trends were not persistent throughout the series length, but depended on the period examined. Recent trends in Southwest precipitation are directionally consistent with anthropogenic climate change.
}, author = {Emile H. Elias and A. Rango and D. K. James and Connie J. Maxwell and John P. Anderson and John T Abatzoglou} } @article {JRN54560, title = {Defoliation of Flourensia cernua (tarbush) with high-density mixed-species stocking}, journal = {Journal of Arid Environments}, volume = {130}, year = {2016}, month = {04/2016}, pages = {62-67}, chapter = {62}, abstract = {

Interest in shrub use by livestock is increasing along with the rising demands placed on rangelands worldwide. Historically, Flourensia cernua (tarbush) has increased in the Chihuahuan Desert but receives limited use by cattle. Cattle, sheep and goats co-grazed eight 0.6 ha tarbush-dominated paddocks during two periods for up to nine days during two consecutive years. Cumulative tarbush defoliation across periods and years averaged 75.6\%, with a mean increase of 9.3\%/day (P \< 0.0001). Defoliation of individual shrubs varied from 5 to 99\% in 1989 and 0 - 100\% in 1990, indicating highly variable palatability among individual plants. Sheep lost 2.3 - 5.5 kg/hd (P \< 0.0001) across periods and years when forced to browse tarbush. In 1989, goats gained (P . 0.0345) 0.6 kg/hd in period 1, but the gain in period 2 was not significant (P . 0.2934). During 1990, goats lost 3.1 kg/hd (P . 0.0001) across periods. High-density mixed-species stocking of small areas for short time periods resulted in extensive tarbush use, primarily due to browsing by sheep and goats. Targeted use of tarbush for short time intervals may increase use of this highly nutritious forage and potentially serve as a form of biocontrol for this shrub.

}, keywords = {biocontrol, browsing, cattle, goats, sheep, shrubs}, doi = {10.1016/j.jaridenv.2016.03.013}, url = {/files/bibliography/16-008.pdf}, author = {Richard E. Estell and D.M. Anderson and D. K. James} } @conference {JRN54638, title = {Deducing dust emission mechanisms from field measurements}, booktitle = {9th International Conference on Aeolian Research}, year = {2016}, month = {07/2016}, publisher = {International Conference on Aeolian Research}, organization = {International Conference on Aeolian Research}, address = {Mildura, Australia}, abstract = {
Field observations are needed to both develop and test theories on dust emission for use in global modeling systems. The mechanism of dust emission (aerodynamic entrainment, saltation bombardment, aggregate disintegration) and the amount and particle-size distribution of emitted dust may vary under sediment supply- and transport-limited conditions. This complexity, which is caused by heterogeneity of the surface and the atmosphere, cannot be fully captured in either field measurements or models. However, uncertainty in dust emission modeling can be reduced through more detailed observational data on the dust emission mechanism itself. To date, most measurements do not provide enough information to allow for a determination of the mechanisms leading to dust emission and often focus on a small variety of soil and atmospheric settings. Additionally, data sets are often not directly comparable due to different measurement setups. As a consequence, the calibration of dust emission schemes has to rely on a selective set of observations, which leads to an idealization of the emission process in models and thus affects dust budget estimates. Here, we will present preliminary results of a study which aims to decipher the dust emission mechanism from field measurements as an input for future model development. Detailed and standardized field measurements will be conducted, which allow for a differentiation between dust emission mechanisms and for a comparison of dust emission for different surface and atmospheric conditions. Measurements include monitoring of the surface, loose erodible material, transported sediment, and meteorological data, and are conducted in different environmental settings in the southwestern United States.
}, author = {Martina Klose and Nicholas Webb and Justin Van Zee and Brad Cooper and Scott Van Pelt and Gregory S. Okin and Jason W. Karl} } @conference {JRN54613, title = {Disentangling dust emission mechanisms {\textendash} a field study}, booktitle = {American Geophysical Union Fall Meeting}, year = {2016}, month = {12/2016}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {

Field observations are needed to both develop and test theories on dust emission for use in global modeling systems. The dust emission mechanism (aerodynamic entrainment, saltation bombardment, aggregate disintegration) as well as the amount and particle-size distribution of emitted dust may vary under sediment supply- and transport-limited conditions. This variability, which is caused by heterogeneity of the surface and the atmosphere, cannot be fully captured in either field measurements or models. However, uncertainty in dust emission modeling can be reduced through more detailed observational data on the dust emission mechanism itself. To date, most measurements do not provide enough information to allow for a determination of the mechanisms leading to dust emission and often focus on a small variety of soil and atmospheric settings. Additionally, data sets are often not directly comparable due to different measurement setups. As a consequence, the calibration of dust emission schemes has to rely on a selective set of observations, which leads to an idealization of the emission process in models and thus affects dust budget estimates. Here, we will present preliminary results of a study which aims to decipher the dust emission mechanism from field measurements as an input for future model development. Detailed and standardized field measurements are conducted, which allow for a differentiation between dust emission mechanisms and for a comparison of dust emission for different surface and atmospheric conditions. Measurements include monitoring of the surface, loose erodible material, transported sediment, and meteorological data, and are conducted in different environmental settings in the southwestern United States.

}, author = {Martina Klose and Peterson, Sharalyn and Nicholas Webb and Justin Van Zee and Brad Cooper and Scott Van Pelt and Thomas E. Gill and Gregory S. Okin and Jason W. Karl} } @conference {JRN54641, title = {Deriving empirical benchmarks from existing monitoring datasets for rangeland adaptive management}, booktitle = {Society for Range Management Meeting}, year = {2016}, month = {01/2016}, publisher = {Society for Range Management Meeting Abstracts}, organization = {Society for Range Management Meeting Abstracts}, address = {Corpus Christi ,TX}, abstract = {
Under adaptive management, goals and decisions for managing rangeland resources are shaped by requirements like the Bureau of Land Management{\textquoteright}s (BLM{\textquoteright}s) Land Health Standards, which specify desired conditions. Without formalized, quantitative benchmarks for triggering management actions, adaptive management is challenging and subjective. Traditionally, monitoring and management benchmarks have been derived from key sites or expert opinion. However, these techniques are limited by time, scale, subjectivity, and may inform only on conditions that are no longer achievable. Empirical approaches for developing benchmarks for different indicators based on a growing corpus of rangeland monitoring data may provide a useful and defensible alternative. We describe use of BLM Assessment, Inventory, and Monitoring program data from northern California to establish quantitative monitoring benchmarks for BLM{\textquoteright}s Land Health Standards. Bare ground, canopy gap, and perennial grass cover were explored as testbed indicators. Benchmarks are necessarily tied to land potential units (e.g., ecological sites) and can be used to assign categories (e.g. {\textquotedblleft}meets objectives{\textquotedblright} and {\textquotedblleft}does not meet objectives{\textquotedblright}). When an indicator{\textquoteright}s value range is broadly distributed and encompasses potential reference conditions, as with bare ground and canopy gap, simple quantiles may be sufficient for setting criteria. For indicators with narrow and skewed distributions due to disturbance or management legacies, (e.g. perennial grass cover), this technique has limited application. Comparing conditions across land potential units is simpler with categories than with numerical values. Additionally, summarizing areas of interest by the proportion of sample units meeting success criteria makes clear that, although an area may overall meet management objectives, portions may not. This approach has potential for broad application, particularly with existing and ever-growing quantitative monitoring datasets available, and complements historic approaches which remain viable options in some cases.
}, author = {Nelson Stauffer and Jason W. Karl and Sarah McCord and Scott W. Miller} } @conference {JRN54417, title = {Distinguishing linear, nonlinear, transient and persistent vegetation dynamics to characterize empirical signatures of ecological resilience}, booktitle = {100th Annual Meeting, Ecological Society of America}, year = {2015}, month = {08/2015}, publisher = {ESA}, organization = {ESA}, address = {Baltimore, MD}, abstract = {

Background/Question/Methods To characterize and interpret ecological resilience and state change is a fundamental question in ecology. In the same ecosystem, across different communities, one can encounter relative stability, abrupt directional shifts, transient reversible change, as well as nondirectional drift through time. These behaviors can be regarded as varying expressions of ecological resilience. Analytical protocols, which can characterize and distinguish such behaviors and clarify relevant timescales, are generally limited in their ability to detect nonlinear events in multivariate ecological data. We explore whether and how four major types of vegetation dynamics: reversible change, nondirectional drift, abrupt directional change, and relative stability, can be distinguished in ecological time series. We analyzed 12 long-term replicated vegetation records based on permanent plots in North American grasslands to quantify the four types of vegetation dynamics through distance-based metrics of community change.
Results/Conclusions: Overall, relative stability and non-directional drift were the most common behaviors. Compositional stability was most common in the shortgrass and tallgrass sites. Abrupt directional vegetation shifts were recorded at the mixedgrass sites, sagebrush steppes, and in annual grasslands. Reversible dynamics were less frequent, but occurred in nearly all sites. These results quantify relative occurrence of different dynamics and offer insights into resilience-profiles of ecosystems. They also provide quantitative metrics that offer opportunities for application of resilience concepts to interpret ecosystem dynamics.\  Abstract $\#$ OOS 71-6.

}, author = {Bagchi, Sumanta and Singh, Navinder and Brandon T Bestelmeyer and D.D. Briske} } @article {JRN54148, title = {Desertification, land use, and the transformation of global drylands}, journal = {Frontiers in Ecology and the Environment}, volume = {13}, year = {2015}, month = {02/2015}, pages = {28-36}, chapter = {28}, abstract = {

Desertification is an escalating concern in global drylands, yet assessments to guide management and policy responses are limited by ambiguity concerning the definition of {\textquotedblleft}desertification{\textquotedblright} and what processes are involved. To improve clarity, we propose that assessments of desertification and land transformation be placed within a state change{\textendash}land-use change (SC{\textendash}LUC) framework. This framework considers desertification as state changes occurring within the context of particular land uses (eg rangeland, cropland) that interact with land-use change. State changes that can be readily reversed are distinguished from regime shifts, which are state changes involving persistent alterations to vegetation or soil properties. Pressures driving the transformation of rangelands to other types of land uses may be low, fluctuating, or high, and may influence and be influenced by state change. We discuss how the SC{\textendash}LUC perspective can guide more effective assessment of desertification and management of drylands.

}, keywords = {desertification, land management, land use, land use change, SC-LUC, state change}, doi = {10.1890/140162}, url = {/files/bibliography/15-004.pdf}, author = {Brandon T Bestelmeyer and Gregory S. Okin and Danielle Duni and Steven R. Archer and N. F. Sayre and Jebediah C. Williamson and Jeffrey E. Herrick} } @conference {JRN54405, title = {Digital soil mapping as a tool for quantifying state-and-transition models}, booktitle = {68th Annual Meeting of Society for Range Management}, year = {2015}, month = {02/2015}, publisher = {Sociiety for Range Management}, organization = {Sociiety for Range Management}, address = {Sacramento, CA}, abstract = {

Ecological sites and associated state-and-transition models (STMs) are rapidly becoming important land management tools in rangeland systems in the US and around the world. Descriptions of states and transitions are largely developed from expert knowledge and generally accepted species and community level responses to external drivers. A major limitation of current STMs is the lack of quantitative data on vegetation dynamics to describe state transitions. Detailed soil property characterization is also needed to better understand soil-landscape controls of state transitions resulting from land use and climate drivers. We used spatiotemporal patterns of normalized difference vegetation index (NDVI) response to precipitation and soil properties in southeastern Arizona to determine how hydraulic soil properties mediate attributes of vegetation dynamics at a landscape level. Pixels in a time series of NDVI derived from Landsat reflectance data were clustered according to types of vegetation dynamics for each pixel-time series combination. Clustered time series data were linked to a high-resolution digital soil map of physical soil properties related to soil moisture dynamics to help explain vegetation response patterns. Monthly PRISM climate data was used to interpret vegetation dynamics. Linking high-resolution soil property maps with vegetation dynamics at broad scales can be used to quantify the interactions between soil properties and land use/climate drivers on vegetation. This process can also be used for forecasting climate change effects on vegetation at relatively fine spatial scales.

}, author = {Matthew Levi and Brandon T Bestelmeyer and Joel R. Brown} } @conference {JRN54157, title = {Detection of honey mesquite leaves in cattle diets using fecal near infrared reflectance spectroscopy}, booktitle = {68th Annual Society for Range Management Meeting}, year = {2015}, month = {01/2015}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Sacramento, CA}, abstract = {

Honey mesquite (Prosopis glandulosa Torr.) is a common invasive shrub whose leaves contain secondary compounds that limit consumption by cattle. However, crude protein and fiber levels of mesquite leaves are similar to alfalfa hay. The ability to consume small quantities of mesquite leaves might make cattle more adaptable to southwestern rangelands. The objective of this study was to determine if consumption of mesquite leaves by cattle could be detected using fecal near infrared reflectance spectroscopy (NIRS). Six cannulated cows were fed either a cool season, warm season or cool and warm season mix grass hay ad libitum. Dry ground mesquite leaves were placed directly in the cannula to achieve 0, 1, 3 and 5\% of the diet. Each level of mesquite was fed for 7 days and then increased to the next concentration. Fecal samples were collected on day 6 and 7, dried, ground, and analyzed using NIRS. Samples were separated into calibration (warm and cool season grass) and validation data sets (mix). Hay intake dropped dramatically for 3 of the 6 cows at the 5\% mesquite level. No problems with intake or behavior were evident when mesquite comprised 3\% or less of the diet. Fecal NIRS under-predicted mesquite in diet at 0 and 1\% levels when two 0\% mesquite samples from the validation data set were included in the calibration and over-predicted mesquite at all levels without validation samples in the calibration. Including the 0\% mesquite fecal samples reduced the bias at higher mesquite levels (3 and 5\%) by about 1 percentage unit compared to calibrations without fecal samples from the 0\% diet. Simple coefficient of determinations did not differ (P \> 0.50) between the two calibrations and were about 0.70. Fecal NIRS may have the ability to estimate the amount of mesquite leaves consumed by cattle grazing rangelands.

}, author = {Piedad Mayagoitia and J.W. Walker and Pittarello, Marco and Richard E. Estell and C. Donovan Bailey} } @conference {JRN54404, title = {Detecting long-term vegetation change in an arid rangeland ecosystem: Investigating effects of spatial image support within satellite time-series}, booktitle = {68th Annual Meeting of the Society for Range Management}, year = {2015}, month = {02/2015}, publisher = {Sociiety for Range Management}, organization = {Sociiety for Range Management}, address = {Sacramento, CA}, abstract = {

Arid rangelands within the southwestern United States have been severely degraded over the past century due to intensive land-use practices (e.g., livestock overgrazing, recreation) and the increasing effects of drought and climate change. Consequently, there is a critical need to develop monitoring approaches that can detect significant changes in vegetation health and distribution across vast spatial extents. Multi-temporal remote sensing techniques are ideally suited to address these challenges; however, considerable uncertainty exists regarding the effects of changing image resolution on the ability to detect ecologically meaningful change from satellite time-series. The main objective of this study was to explicitly test the effects of changing image resolution on the ability of NDVI time-series to detect observed long-term changes in plant biomass.\  Satellite time series of NDVI were compiled for the period between 2000 and 2013 from the Landsat (30-meter, ~16-day resolution) and MODIS (250-meter, 16-day resolution) sensors at the Jornada Experimental Range (JER) in southwestern New Mexico. Each time-series image was coarsened using mean resampling to yield a range of spatial resolutions (i.e., Landsat: 30, 90, 240, 990 meters; MODIS: 250, 500, 1000, 3000 meters).\  Long-term plant biomass data from 15 sites at the JER, representing both grassland and shrubland ecosystems, were used to examine these scaling effects. Each time-series was decomposed into seasonal and long-term trend components using the Breaks For Additive Seasonal and Trend (BFAST) model and significant deviations from modeled trends were identified. Plant biomass data was then regressed against the decomposed time-series, with model results used to identify optimal spatial scales. Preliminary results indicate that finer resolution imagery produces stronger correlations with temporal shifts in plant biomass. However, when considering the use of finer resolution imagery, any potential improvement in identifying shifts in vegetation dynamics must be weighed against the higher computational requirements involved with its use.

}, author = {Jonathan Maynard and Jason W. Karl and Dawn M. Browning} } @conference {JRN54504, title = {Dust-on-snow and the timing of peak streamflow in the upper Rio Grande}, booktitle = {American Geophysical Union Fall Meeting}, year = {2015}, month = {12/2015}, publisher = {AGU}, organization = {AGU}, address = {San Francisco, CA}, abstract = {

Dust radiative forcing on high elevation snowpack is well-documented in the southern Rockies. Various field studies show that dust deposits decrease snow albedo and increase absorption of solar radiation, leading to earlier snowmelt and peak stream flows. These findings have implications for the use of temperature-index snow runoff models (such as the Snowmelt Runoff Model [SRM]) for predicting streamflow. In previous work, we have used SRM to simulate historical streamflow from 26 Upper Rio Grande sub-basins. Because dust radiative forcing can alter the relation between temperature and snowmelt, we wanted to find out if there is evidence of dust radiative forcing and earlier snowmelt in our study basins, particularly for those years where SRM was less successful in simulating streamflow. To accomplish this we have used openly-available data such as EPA air quality station measurements of particulate matter up to 10 micrometers (PM10); streamflow data from the USGS National Water Information System and Colorado Division of Water Resources; temperature, precipitation and snow water equivalent (SWE) from NRCS SNOTEL stations and remotely sensed data products from the MODIS sensor. Initial analyses indicate that a connection between seasonal dust concentration and streamflow timing (date of onset of warm-season snowmelt, date of streamflow center-of-volume) can be detected. This is further supported by time series analysis of MODIS-derived estimates of snow albedo and dust radiative-forcing in alpine and open subalpine snow fields.

}, author = {Caitriana Steele and Emile H. Elias and Moffitt, Ashlie and Beltran, Ismael and A. Rango} } @article {JRN54150, title = {Deforestation of "degraded" rangelands: The Argentine Chaco enters the next state of the anthropocene}, journal = {Rangelands}, volume = {36}, year = {2014}, month = {08/2014}, pages = {36-39}, chapter = {36}, abstract = {

Twenty years ago I completed my Master\’s work in the Chaco forests of northern Argentina. The native forests are, in fact, rangelands. In addition to livestock grazing, there is timber extraction, wildlife harvest (think tegu lizard cowboy boots), and charcoal production. I took part in a project comparing biodiversity among production systems. A new system promised to reverse biodiversity loss and soil degradation. But it\’s a moot point now since much of that forest has been cleared for cropland\—the highest rate of tropical forest loss in the world.

}, doi = {10.2111/Rangelands-D-14-00026.1}, url = {/files/bibliography/14-033.pdf}, author = {Brandon T Bestelmeyer} } @article {JRN53927, title = {Is differential use of Juniperus monosperma by small ruminants driven by terpenoid concentration}, journal = {Journal of Chemical Ecology}, volume = {40}, year = {2014}, month = {02/2014}, pages = {285-293}, chapter = {285}, abstract = {

We examined the relationship between volatile plant secondary metabolite concentrations and Juniperus monosperma herbivory by small ruminants. Two groups of animals (10 goats or 5 goats plus 4 sheep) browsed 16 paddocks (20 x 30 m) containing one-seed juniper for six days during two seasons. Juniper leaves were sampled from 311 saplings on the same day they were browsed. Saplings were categorized by size (short [\< 0.5 m], medium [0.5-1.0 m] or tall [\> 1.0 m]) and browsing intensity (light [\< 33\%], moderate [33-66\%] or heavy [\> 66\%]). Juniper bark was also collected from 12 saplings during spring. Total estimated terpenoid concentrations in leaves and bark were 18.3 \± 0.3 and 8.9 \± 0.8 mg/g, respectively, and the dominant terpene in both tissues was a-pinene (11.1 \± 0.2 and 7.6 \± 0.7 mg/g, respectively). Total terpenoid concentration was greater (P \< 0.001) in spring than summer (20.6 \± 0.5 vs. 16.7 \± 0.3 mg/g, respectively) and lower (P \< 0.001) in short saplings than medium or tall saplings (16.5 \± 0.6 vs. 19.8 \± 0.4 and 19.5 \± 0.4 mg/g, respectively). Total concentration also differed (P \< 0.001) among the three defoliation categories (16.1 \± 0.4, 18.7 \± 0.5, and 21.2 \± 0.6 mg/g for heavy, moderate, and light, respectively). The smallest subset of terpenes able to discriminate (P \< 0.001) between heavy and light browsing intensity categories included eight compounds ([E]-\ß-farnesene, bornyl acetate, \&$\#$39;-eudesmol, endo-fenchyl acetate, y-cadinene, a-pinene, cis-piperitol, and cis-p-menth-2-en-1-ol).

}, keywords = {goats, herbivory, one-seed juniper, Oxygenated terpenes, Resource availability hypothesis, sheep, targeted grazing, terpenes}, doi = {10.1007/s10886-014-0389-1}, url = {/files/bibliography/14-006.pdf}, author = {Richard E. Estell and S. A. Utsumi and Andr{\'e}s F. Cibils and D.M. Anderson} } @article {JRN54175, title = {Discernment of lint trash in raw cotton using multivariate analysis of excitation-emission luminescence spectra}, journal = {Journal Analyt Molecul Tech}, volume = {1}, year = {2014}, month = {05/2014}, pages = {9}, abstract = {

Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component Analysis (U-PCA) was applied to Rayleigh-corrected extract spectra from each plant component. This enabled distinction of seeds, stems, bracts and leaves as trash material. Sensitivity of U-PCA models to sample replicate selection was evaluated. This revealed significant sample dependence for U-PCA models using spectra from stems of both Pima and upland cotton varieties. Dependencies were also observed for seeds, burrs, walls, and fiber from Pima cotton. Spectra from fiber and seed samples of upland cotton also exhibited significant sample-selection sensitivity on U-PCA models. Application of parallel factor analysis (PARAFAC) further revealed three spectral factors enabling trash identification. Elucidated excitation and emission spectra of these factors exhibited excitation wavelengths of maximum intensity of 295, 320, and 400 nm and respective emission wavelengths of 348, 435, and 473 nm. These suggest the presence of 1) tryptophan-containing proteins or polypeptides, 2) NADH, periodic acid, or periodic acid-5{\textquoteright}-phosphate, and 3) 6,7-dihydoxy or 7-hydroxy-6-methoxy coumarins as discriminating components.

}, keywords = {fluorescence, parallel factor analysis, Pima cotton, principal component analysis, Upland cotton}, url = {/files/bibliography/14-034.pdf}, author = {Gamez, Elizabeth and Jiang, Fengshan and Ghale, Surja B. and Hughs, S.E. and D.M. Anderson and G.D. Rayson} } @article {JRN53970, title = {A double-sampling approach to deriving training and validation data for remotely-sensed vegetation products}, journal = {International Journal of Remote Sensing}, volume = {35}, year = {2014}, month = {02/2014}, pages = {1936-1955}, chapter = {1936}, abstract = {

The need for large sample sizes to train, calibrate, and validate remote-sensing products has driven an emphasis toward rapid, and in many cases, qualitative field methods. Double-sampling is an option for calibrating less-precise field measurements with data from a more precise method collected at a subset of sampling locations. While applicable to the creation of training and validation datasets for remote-sensing products, double-sampling has rarely been used in this context. Our objective was to compare vegetation indicators developed from a rapid ocular-estimation field protocol with the quantitative field protocol used by the Bureau of Land Management{\textquoteright}s Assessment, Inventory and Monitoring (AIM) program to determine if double-sampling could improve the relationship between field data and high-resolution satellite imagery.\  We used beta-regression to establish the relationship between AIM- and ocular-protocol estimates of vegetation cover from 50 field sites in the Piceance Basin of northwestern Colorado, USA. Using the defined regression models for eight vegetation indicators we adjusted the ocular-protocol estimates and compared the results, along with the original measurements, to 5m-resolution RapidEye satellite imagery. We found good correlation between AIM- and ocular-protocol estimates for dominant site components like shrub cover and bare ground, but low correlations for minor site components (e.g., annual grass cover) or indicators where observers were required to estimate over multiple life forms (e.g., total canopy cover). Correcting the ocular-protocol estimates with the AIM-protocol data significantly improved correlation with the RapidEye imagery for most indicators. As a means of improving training data for remote sensing projects, double-sampling should be used where a strong relationship exists between quantitative and qualitative field techniques. Accordingly, ocular techniques should be used only when they can generate reliable estimates of vegetation cover.

}, doi = {10.1080/01431161.2014.880820}, url = {/files/bibliography/14-019.pdf}, author = {Jason W. Karl and Jason Taylor and Matthew Bobo} } @conference {JRN54411, title = {Disaggregation of soil map units for improved ecological site mapping in rangelands}, booktitle = {Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meetings 2014}, year = {2014}, month = {11/2014}, publisher = {ASA, CSSA, SSSA}, organization = {ASA, CSSA, SSSA}, address = {Long Beach, CA}, abstract = {

Rangeland soils are often mapped with soil map units consisting of associations, complexes, and undifferentiated groups composed of varied soil components. Because different components may be related to different ecological sites, the unmapped heterogeneity within map units limits the potential uses of ecological sites for planning and assessment. Advances in digital soil mapping (DSM) techniques coupled with readily available environmental covariate layers present an opportunity to identify unique soil components that can provide a more detailed spatial representation of ecological sites. Our objectives were to utilize environmental covariate data and DSM techniques to identify individual soil components and ecological sites in a semiarid landscape of southeastern Arizona (~72,000 ha). We used a time-series of Landsat reflectance, high-resolution orthoimagery and a digital elevation model to derive indices reflecting soil, vegetation and topographic attributes. An unsupervised classification of the environmental covariates was performed with a maximum likelihood classification of isodata clusters to create unique landscape units. Field data from initial soil survey efforts were digitized and supplemented with additional targeted sampling locations to attribute landscape classes. Classification of integrated environmental covariate layers separated existing soil map unit boundaries and different soil components. Classified soil landscape units also captured information in detailed maps of ecological states illustrating the utility of linking DSM with ecological sites and states to provide rapid characterization of the landscape for improving rangeland management. Incorporating multiple imagery dates in the classification provided a means to overcome problems of management differences on the ground (e.g., fence lines) to facilitate more realistic separation of soil properties. Disaggregating soil map units into more explicit soil components presents a unique opportunity for developing a hierarchical soil map scalable to desired objectives that can overcome many of the problems associated with multi-component maps.

}, author = {Matthew Levi and Brandon T Bestelmeyer and Joel R. Brown} } @conference {JRN54123, title = {Disaggregation of soil map units for improved ecological site mapping in rangelands}, booktitle = {Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting}, year = {2014}, month = {11/2014}, publisher = {ASA CSSA, SSSA}, organization = {ASA CSSA, SSSA}, address = {Long Beach, CA}, abstract = {

Rangeland soils are often mapped with soil map units consisting of associations, complexes, and undifferentiated groups composed of varied soil components. Because different components may be related to different ecological sites, the unmapped heterogeneity within map units limits the potential uses of ecological sites for planning and assessment. Advances in digital soil mapping (DSM) techniques coupled with readily available environmental covariate layers present an opportunity to identify unique soil components that can provide a more detailed spatial representation of ecological sites. Our objectives were to utilize environmental covariate data and DSM techniques to identify individual soil components and ecological sites in a semiarid landscape of southeastern Arizona (~72,000 ha). We used a time-series of Landsat reflectance, high-resolution orthoimagery and a digital elevation model to derive indices reflecting soil, vegetation and topographic attributes. An unsupervised classification of the environmental covariates was performed with a maximum likelihood classification of isodata clusters to create unique landscape units. Field data from initial soil survey efforts were digitized and supplemented with additional targeted sampling locations to attribute landscape classes. Classification of integrated environmental covariate layers separated existing soil map unit boundaries and different soil components. Classified soil landscape units also captured information in detailed maps of ecological states illustrating the utility of linking DSM with ecological sites and states to provide rapid characterization of the landscape for improving rangeland management. Incorporating multiple imagery dates in the classification provided a means to overcome problems of management differences on the ground (e.g., fence lines) to facilitate more realistic separation of soil properties. Disaggregating soil map units into more explicit soil components presents a unique opportunity for developing a hierarchical soil map scalable to desired objectives that can overcome many of the problems associated with multi-component maps.

}, author = {Matthew Levi and Brandon T Bestelmeyer and Joel R. Brown} } @article {JRN54047, title = {Differential sensitivities of grassland structural components to changes in precipitation mediate productivity response in a desert ecosystem}, journal = {Functional Ecology}, volume = {28}, year = {2014}, pages = {1292-1298}, abstract = {

1. In arid and semi-arid ecosystems, there are legacies of previous-year precipitation on current- year above-ground net primary production. We hypothesized that legacies of past precipitation occur through changes in tiller density, stolon density, tiller growth, axillary bud density and percentage of viable axillary buds. We examined the sensitivity to current- and previousyear precipitation of these grassland structural components in Bouteloua eriopoda, the dominant grass in the northern Chihuahuan Desert.

2. We conducted a rainfall manipulation experiment consisting in -80\% reduced precipitation, ambient, +80\% increased precipitation treatments that were subjected to one of five precipitation levels in the previous two years (-80\% and -50\% reduced precipitation, ambient, +50\% and +80\% increased precipitation). The first two years preconditioned the experimental plots for year three, in which we created wet-to-dry and dry-to-wet transitions. Measurements were taken in year 3.

3. We found that stolon density was the most sensitive to changes in precipitation and that percent-active buds were insensitive.

4. We also found that past precipitation had a significant legacy on grassland structural components regardless of the precipitation received in the current year, and that the legacy occurs mostly through changes in stolon density.

5. Here, we showed that there is a differential sensitivity of structural components to current and past precipitation and supported previous findings that vegetation structure is one of the controls of productivity during precipitation transitions.

}, keywords = {axillary buds, Bouteloua eriopoda, desert grassland, meristem bank, precipitation legacies, rainfall manipulation, vegetative reproduction}, doi = {10.1111/1365-2435.12265}, url = {files/bibliography/JRN00622.pdf}, author = {Lara Reichmann and O. E. Sala} } @article {JRN53966, title = {Discovering ecologically relevant knowledge from published studies through geosemantic searching}, journal = {BioScience}, volume = {63}, year = {2013}, month = {08/2013}, pages = {674-682}, chapter = {674}, abstract = {

It is easier to search the globe for research on genes of a local plant or animal than to find local field research on that plant{\textquoteright}s ecology.\  While internet applications can find the closest coffee shop, it is difficult to find where the nearest relevant research was conducted.\  As a result, ecologists are often unaware of published local research, and are unlikely to find relevant studies from similar environments worldwide.\  Location information in ecological studies can be harnessed to enable geographic knowledge searches, and could be standardized to make searches more fruitful. To demonstrate this potential, we developed the JournalMap website (http://www.journalmap.org). Easy access to geographic distributions of knowledge opens new possibilities for using ecological research to detect and interpret ecological patterns and trends, evaluate current ecological knowledge, and facilitate knowledge creation. We call on journals and publishers to support standard reporting of study locations in publications and metadata, and we advocate for geo-referencing of past studies.

}, keywords = {georeferencing, knowledge discovery, metadata, semantic search, spatial distribution}, doi = {10.1525/bio.2013.63.8.10}, url = {/files/bibliography/13-038.pdf}, author = {Jason W. Karl and Jeffrey E. Herrick and Unnasch, Robert S. and Jeffrey K. Gillan and Ellis, Erie and Lutters, Wayne and Martin, Laura} } @inbook {49858, title = {Desertification of Rangelands}, booktitle = {Climate Vulnerability: Understanding and Addressing Threats to Essential Resources}, series = {Climate Vulnerability}, volume = {4}, number = {4}, year = {2013}, pages = {239-258}, publisher = {Academic Press}, organization = {Academic Press}, edition = {First}, abstract = {Desertification, the broad-scale conversion of perennial grasslands to dominance by xerophytic shrubs, and the attendant consequences to ecosystem services has affected arid and semiarid regions globally over the past several centuries. This state change is expected to continue in the future as environmental drivers continue to change. It is generally well-recognized that desertification is a cumulative threat that explicitly includes both climatic (e.g., drought) and land-use drivers (e.g., livestock overgrazing and inappropriate conversions of rangeland to cropland).\  However, a basis for ranking the relative importance of these drivers is lacking for many locations. In addition, the emergence of additional drivers (e.g., non-native forbs and grasses modifying historic fire regimes), will result in even more complex dynamics in the future. Clearly, directional changes in climate can have unanticipated effects, in particular for dryland regions with low and variable precipitation and high temperatures in the growing season. However, any change in climate will be operating across diverse landscapes that include a mosaic of human-dominated and natural states, each governed by different drivers and susceptible to different threats. Accounting for the separate and interactive effects of these threats on grassland-shrubland transitions will be necessary as we move forward into a difficult to predict, if not unknown, environmental world.}, keywords = {biodiversity, climate, desertification, dryland ecosystems, feedbacks, grasslands, invasive species, land management, land use, land-atmosphere interactions, shrublands, state change, thresholds, water, wind}, doi = {10.1016/B978-0-12-384703-4.00426-3}, url = {/files/bibliography/13-014.pdf}, author = {Debra C. Peters and Steven R. Archer and Brandon T Bestelmeyer and Brooks, Andrew and Joel R. Brown and Comrie, Andrew and Gimblett, H. Randy and Goldstein, Joshua H. and Kris Havstad and Lopez-Hoffman, L. and Curtis H. Monger and Gregory S. Okin and A. Rango and O. E. Sala and Craig Tweedie and Enrique Vivoni} } @inbook {JRN52667, title = {Disturbance regimes and ecological responses across sites}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {58-71}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {9}, address = {Springfield, Virginia}, abstract = {

Disturbances affect ecosystems in almost limitless ways. The effects of disturbances extend beyond the initial impacts that are usually visible to the human eye. Therefore, for many disturbances long-term data are needed to unravel their effects.\  This chapter first presents characteristics of disturbances for each of four major classes of disturbance: climatic, physical, biotic, and anthropogenic.\  It then discusses ecosystem responses by disturbance class.\  For climatic disturbances, ecosystem responses to hurricanes, drought, and global warming are discussed; for physical disturbances, wildfire on land and wave height in ocean; for biotic disturbance, herbivores feeding on lower tropic levels, invasive species, and a plant disease; for anthropogenic disturbance, changes in land use patterns.\  These long-term records of ecosystem responses to disturbance illustrate the complexity of disturbance effects. Ecosystem responses are influenced by multiple disturbances and interactions with other factors, which make it very difficult to attribute cause and effect. Clearly large-scale, multiple-site experiments are needed to further unravel the relationships between particular disturbance events and ecosystem responses.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-9.pdf}, author = {Debra C. Peters and Ariel E. Lugo and F.S. Chapin III and Tepley, A. J. and F. J. Swanson} } @article {49865, title = {Density fractionation and 13C reveal changes in soil carbon following woody encroachment in a desert ecosystem}, journal = {Biogeochemistry}, volume = {112}, year = {2013}, month = {03/2013}, pages = {409-422}, chapter = {409}, abstract = {Woody encroachment has dramatically changed land cover patterns in arid and semiarid systems (drylands) worldwide over the past 150 years. This change is known to influence bulk soil carbon (C) pools, but the implications for dynamics and stability of these pools are not well understood. Working in a Chihuahuan Desert C4 grassland encroached by C3 creosote bush (Larrea tridentata), we used two density fractionation techniques (2 and 7 pool density fractionations) and isotopic analysis to quantify changes in C pools and dynamics among vegetation microsites typical of an encroachment scenario (remnant intact grassland, shrub subcanopies, and in shrub intercanopy spaces within a shrubencroached area). The C concentration of bulk soils varied with microsite, with almost twice the C in shrub subcanopies as in intercanopy spaces or remnant grasslands. Estimated SOC accumulation rates from Larrea encroachment (4.79 g C m-2 year-1 under canopies and 1.75 g C m-2 year-1 when intercanopy losses were taken into account) were lower than reported for higher productivity Prosopis systems, but still represent a potentially large regional C sink. The composition of soil C varied among microsites, with the shrub subcanopy C composed of proportionally more light fraction C (\1.85 g cm-3) and C that was soluble in sodium polytungstate. Grassland soils contained very little carbonate C compared to shrub subcanopies or shrub intercanopy spaces. Stable isotope analyses indicate that inputs from C3 shrubs were incorporated into all density fractions, even in heavy fractions in which shrub inputs did not change overall C concentration. The seven density fractionation yielded unexpected \ð13C patterns, where the two heaviest fractions were strongly depleted in 13C, indicating strong fractionation following organic matter inputs. These results suggest that the utility of isotope mixing models for determining input sources may be limited in systems with similar fractionation patterns. We propose a five pool model for dryland soil C that includes a relatively dynamic light fraction, aggregate and heavy fractions that are stable in size but that reflect dynamic inputs and outputs, a potentially large and seasonally dynamic pool of soluble C, and a large pool of carbonate C. Combined, these results suggest that dryland soil C pools may be more dynamic than previously recognized.}, keywords = {black grama grass, Bouteloua, carbonates, creosotebush, dryland, Jornada, Larrea, soil carbon stabilization, soil organic matter, woody encroachment}, doi = {10.1007/s10533-012-9735-y}, url = {/files/bibliography/13-020.pdf}, author = {Heather L. Throop and Kate Lajtha and Kramer, Marc} } @conference {JRN54588, title = {Data support for a state-and-transition model: What have we learned?}, booktitle = {Society for Range Management, 65th Annual Meeting}, year = {2012}, month = {01/2012}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Spokane, WA}, abstract = {

State-and-transition models (STMs) were conceived as a means to synthesize knowledge about alternative plant communities and the processes that lead to transitions among them for specific land areas. STMs that have been developed over the past decade have often been limited by 1) a lack of detail on ecological mechanisms and management effects and 2) an over-reliance on expert knowledge and casual observations that are seldom critically evaluated. We used a state-and-transition model developed 10 years ago, in consultation with local experts, as a basis to examine how a model{\textquoteright}s structure would be changed via changes to model concepts, inclusion of a broad-scale, data-rich inventory dataset, and new experiments and monitoring. We found that elements of the initial model (Sandy ecological site, Chihuahuan Desert, Major Land Resource Area 42.2) were supported by the data, yet others were not. We found that the reference state was more resilient, an eroded shrubland state could attain higher grass cover, and that grasses and shrubs coexist over a wider range of values than previously assumed. We also found that the model could be simplified by reducing the number of states and quantitative criteria for ecological states and community phases were developed. This assessment suggests that a combination of local/expert knowledge and different kinds of data can be brought together to produce improved STMs. Even if this level of effort is not possible for all STMs in area, it should be possible for widespread or {\textquotedblleft}benchmark{\textquotedblright} ecological sites in most Major Land Resource Areas.

}, author = {Brandon T Bestelmeyer and D.D. Briske and Maria Fern{\'a}ndez-Gim{\'e}nez and Wu, X.B.} } @proceedings {JRN54531, title = {Deciphering landscape complexity to predict (non)linear responses to extreme climatic events}, volume = {H54D-04}, year = {2012}, month = {12/2012}, publisher = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {Extreme events are increasing in frequency and magnitude for many landscapes globally. Ecologically, most of the focus on extreme climatic events has been on effects of either short-term pulses (floods, freezes) or long-term drought. Multi-year increases in precipitation are also occurring with little known consequences, in particular for landscapes with high spatial variation in soils, geomorphology, and vegetation. We used long-term data from the Chihuahuan Desert in North America to compare ecosystem responses to precipitation in dry, average, and wet periods for a landscape consisting of five major ecosystem types. These types are dominated by one of two life forms (grasses or shrubs) that are located on different soils and topographic positions. We then used a process-based simulation model integrated with additional long-term data to identify the processes driving dynamics in each climatic period for different landscape locations. For some ecosystem types, ecological responses in average and dry periods could be linearly extrapolated to predict responses in an extended wet period, and the same set of processes occurred regardless of climatic period. However, for much of the landscape, a different set of biotic-abiotic processes and their feedbacks became operative in a wet period. This sequence of processes led to nonlinear dynamics through time. Our results show that dynamics of complex landscapes can be deciphered given information and long-term data on linked biotic-abiotic processes across spatial and temporal scales. Understanding the role of sequential processes and landscape complexity in ecosystem responses to multi-year climatic patterns is needed to improve predictions of landscape scale responses to climate.}, author = {Debra C. Peters and Jin Yao and Dawn M. Browning and Danielle Duni and Haitao Huang and A. Rango} } @article {49900, title = {Directional climate change and potential reversal of desertification in arid and semiarid ecosystems}, journal = {Global Change Biology}, volume = {18}, year = {2012}, month = {01/2012}, pages = {151-163}, chapter = {151}, abstract = {Our objective was to determine if long-term increases in precipitation can maintain grasslands susceptible to desertification, and initiate a reversal of historic regime shifts on desertified shrublands. Perennial grass production and species richness in a multi-year wet period were hypothesized to be greater than expected based on precipitation in a sequence of dry years. These responses were expected to differ for grasslands and shrublands with different dominant species and topo-edaphic properties. Long-term trends in desertification were documented using vegetation maps beginning in 1858, 1915, 1928, and 1998). These trends were compared with herbaceous and woody species responses to a sequence of dry (1994\–2003) and wet years (2004\–2008) for two grassland (uplands, playas) and three desertified shrubland types (honey mesquite, creosotebush, tarbush) in the Chihuahuan Desert. Analyses showed that both types of grasslands decreased in spatial extent since 1858 whereas areas dominated by mesquite or creosotebush increased. Production of upland grasslands in the wet period was greater than expected based on responses during the dry period whereas the relationships between species richness and precipitation was the same for both periods. Precipitation was not important to responses in playa grasslands in either period. For all ecosystem types, the production response in wet years primarily was an increase in herbaceous plants, and the most pronounced responses occurred on sandy sites (upland grasslands, mesquite shrubland). Results suggest that multiple wet years are needed to initiate a sequence of grass establishment and survival processes that can maintain upland grasslands without management inputs and lead to a state change reversal in desertified shrublands. Restoration strategies need to take advantage of opportunities provided by future climates while recognizing the importance of ecosystem type.}, keywords = {extreme events, grasslands, regime shift, shrublands, spatial content, wet-dry climatic periods}, doi = {10.1111/j.1365-2486.2011.02498.x}, url = {/files/bibliography/12-002.pdf}, author = {Debra C. Peters and Jin Yao and O. E. Sala and John P. Anderson} } @article {49914, title = {Do long-lived ants affect soil microbial communities?}, journal = {Biology and Fertility of Soils}, volume = {48}, year = {2012}, month = {01/15/2012}, pages = {227-233}, chapter = {227}, abstract = {

This study was designed to test the hypothesis that desert ant species that build nests that remain viable at a particular point in space for more than a decade produce soil conditions that enhance microbial biomass and functional diversity. We studied the effects of a seed-harvester ant, Pogonomyrmex rugosus, and two generalist ant species, Aphaeonogaster cockerelli and Myrmecocystus depilis, on soil microbial communities. Microbial biomass was higher in P. rugosus-modified soils than in reference soils when soil water content was higher than 3\%. Microbial biomass was either higher in reference soils or exhibited no difference in reference soils and nest-modified soils of A. cockerelli and M. depilis. There were differences in microbial functional diversity and microbial community level physiological profiles (MicroResp method) between ant-nest-modified and reference soils of the three ant species on some sampling dates. Temporal pattenrs of soil microbial communities associated with the ant species resulted from differences in soil moisture, density, and species composition of the annual plant c0ommunities associated with the ant nests and in reference areas. Differences in annual plant communities associated with ant nests and surrounding areas resulted in different chemical inputs into the soil organic-matter pools. This study shows that generalizations about the effects of long-lived ant nests on soil biota in arid regions must consider feeding behaviors of the ant species and temporal patterns of rainfall.

}, keywords = {ant, aphaenogaster cockerelli, Climate-Community-level physiological profile, CLPP, functional diversity, honeypot ant, microbial biomass, MicroResp method, Myrmecocystus debilis, Pogonomyrmex rugosus}, doi = {10.1007/s00374-011-0619-4}, url = {/files/bibliography/12-014.pdf}, author = {Walter G. Whitford and O. Ginzburg and Berg, Naama and Yosef Steinberger} } @article {49919, title = {Differentiating among plant spectra by combining pH dependent photoluminescence spectroscopy with multi-way principal component analysis (MPCA)}, journal = {The Open Agriculture Journal}, volume = {5}, year = {2011}, pages = {1-9}, chapter = {1}, abstract = {

Photoluminescence spectroscopic probes offer the potential for real-time measurements of animal diet composition. Spectral emission signatures (excitation at 365 nm) from three different pH (2.2, 7.5 and 12.5) phosphate buffered saline (PBS) extracts from two grasses, Sporobolus flexuosus (Thurb. ex Vasey) Rydb., [mesa dropseed], and Pleuraphis mutica Buckley [tobosa], two forbs, Dimorphocarpa wislizenii (Engelm.) Rollins [spectacle pod], and Sphaeralcea incana Torrey [pale globemallow], and leaves and twigs from two shrubs Flourensia cernua DC. [tarbush], and Atriplex canescens (Pursh) Nutt., [fourwing saltbush] were examined. Since pH has been shown to be pivotal in affecting extraction efficiency of other plant compounds pH seemed appropriate as an additional dimension within our multi-way principal component analysis (MPCA) to differentiate among six different plant species. In particular, MPCA allowed differentiation between Sporobolus and Pleuraphis that was not possible using only principal component analysis (PCA). This research suggests MPCA may be a more appropriate tool than PCA when attempting to discriminate among plant species.

}, keywords = {botanical composition, chemometrics, fluorescence, luminescence, phosphate buffered saline (PBS)}, doi = {10.2174/1874331501105010001 }, url = {/files/bibliography/11-005.pdf}, author = {D.M. Anderson and T.L. Danielson and S. Obeidat and G.D. Rayson and Richard E. Estell and B. Bai and E.L. Fredrickson} } @article {49924, title = {Dust emissions from undisturbed and disturbed, crusted playa surfaces: cattle trampling effects}, journal = {Aeolian Research}, volume = {3}, year = {2011}, month = {05/2011}, pages = {31-41}, chapter = {31}, abstract = { Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM10 emissions from a bare, fine-textured playa surface located in the far northern Chihuahua Desert. The natural, undisturbed crust and its subjection to two levels of animal disturbance (one and ten cow passes) were tested. The wind tunnel generated dust emissions under controlled conditions for firstly an initial blow-off of the surface, followed by two longer runs with sand added to the flow as an abrader material. Dust was measured using a GRIMM particle monitor. For the study playa, no significant differences in PM10 concentration and emission flux were found between the untrampled surface and following a single animal pass. This was the case for both the initial blow-offs and tests on plots under a steady abrader rate. Significantly higher dust loading was only associated with the effect of 10 animal passes. In the blow-offs, the higer PM10 yield after 10 passes reflected the greater availability of easily entrainable fine particles. Under abrasion, the effect of the heaviest trampling increased the emission flux by a third and abrasion efficiency by around 50\% more than values on the untrampled surface. This enhanced abrasion efficiency peristed for a 30 minute period under abrasion before the positive effect of the disturbance was no longer evident. The findings highlight the role of a threshold of disturbance that determines if supply-limited surfaces will exhibit enhanced wind erosion or not after undergoing perturbation.}, keywords = {anthropogenic dust, mineral aerosols, playas, wind erosion, wind tunnel}, doi = {10.1016/j.aeolia.2011.03.007}, url = {/files/bibliography/11-008.pdf}, author = {Matthew C. Baddock and Teddy M. Zobeck and Scott Van Pelt and E.L. Fredrickson} } @article {49935, title = {Digital soil mapping in the absence of field training data: A case study using terrain attributes and semiautomated soil signature derivation to distinguish ecological potential}, journal = {Applied and Environmental Soil Science}, volume = {2001}, year = {2011}, month = {04/2011}, pages = {421904}, chapter = {421904}, abstract = {Spatially-explicit data for soil properties governing plant water availability are needed to understand mechanisms influencing plant species distributions and predict plant responses to changing climate. This is especially important for arid and semi-arid regions. Spatial data representing surrogates for soil forming factors are becoming widely available (e.g. spectral and terrain layers). However, field-based training data remain a limiting factor, particularly across remote and extensive drylands. We present a method to map soils with Landsat ETM+ imagery and high resolution (5 m) terrain (IFSAR) data based on statistical properties of the input data layers that do not rely on field training data. We then characterize soil classes mapped using this semi-automated technique. The method distinguished spectrally distinct soil classes that differed in subsurface rather than surface properties. Field evaluations of the soil classification in conjunction with analysis of long-term vegetation dynamics indicate the approach was successful in mapping areas with similar soil properties and ecological potential.}, doi = {10.1155/2011/421904}, url = {/files/bibliography/11-006.pdf}, author = {Dawn M. Browning and Danielle Duni} } @article {49940, title = {The database for inventory, monitoring, and assessment (DIMA)}, journal = {Rangelands}, volume = {33}, year = {2011}, month = {08/2011}, pages = {21-26}, chapter = {21}, abstract = {Land managers increasingly need to collect, store, and analyze monitoring and assessment datasets that include multiple methods and occur over multiple years. The Database for Inventory,Monitoring and Assessment (DIMA) is a highly customizable software tool for data collection, management, and interpretation. DIMA is a free Microsoft Access database that can be used easily without extensive knowledge of Access (download DIMA from http://jornada.nmsu.edu/monit-assess/dima/download). Data can be entered for common, nationally accepted vegetation and soil monitoring methods in the field using a Tablet PC (touch screen entry) or in the office on a standard computer (keyboard entry) with user-specified choice lists.}, doi = {doi: 10.2111/1551-501X-33.4.21}, url = {/files/bibliography/11-025.pdf}, author = {Ericha Courtright and Justin Van Zee} } @article {49942, title = {Disentangling road network impacts: the need for a holistic approach}, journal = {Journal of Soil and Water Conservation}, volume = {66}, year = {2011}, month = {April 2011}, pages = {31A-36A}, chapter = {31A}, doi = {10.2489/jswc.66.2.31A}, url = {/files/bibliography/11-003.pdf}, author = {Danielle Duni and Jeffrey E. Herrick} } @conference {49943, title = {Distribution of antiherbivory compounds in Flourensia cernua}, booktitle = {American Society of Animal Science Joint Annual Meeting}, year = {2011}, month = {07/2011}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, address = {New Orleans, LA}, abstract = {Flourensia cernua is serving as a shrub model to study the influence of terpenes on intake by livestock at this location. Two studies (n=20 plants per study) were conducted to examine within plant distribution of volatile compounds to improve sampling protocol. Leaves from 3 positions (outer canopy, subcanopy, and basal) were collected from 4 quadrants (based on ordinal direction) in Exp. 1. Leaves were removed from 2 leaders of current year\&$\#$39;s growth for each position in each quadrant. In Exp. 2, 10 leaders of current year\&$\#$39;s growth were collected from the outer canopy in each quadrant and 3 leaf age categories were formed by separating leaders into thirds and removing leaves. Chemicals were extracted from 5 leaves in duplicate with ethanol and analyzed with gas chromatography/mass spectrometry. Data were log transformed and analyzed by univariate ANOVA and means were separated using Tukey\&$\#$39;s HSD. Ninety-three volatile compounds (including 15 unknowns) were present on the leaf surface of F. cernua. Only 7 compounds (including 3 unknowns) in Exp. 1 and 9 in Exp. 2 differed (P\<0.05) among quadrants, and no consistent effect of quadrant was observed in either study. In Exp. 1, 31 compounds differed (P\<0.05) among leaf positions, but outer canopy and subcanopy leaves did not differ for any compound. Basal leaves contained greater concentrations than outer canopy and subcanopy leaves for 10 compounds, and less than the other 2 positions for 10 compounds. Thirty-two compounds differed for leaf age in Exp. 2, with immature leaves containing greater concentrations than mature leaves for 30 compounds and greater than the middle age category for 26 compounds (P\<0.05). Total concentration (cumulative concentration of all compounds) did not differ among leaf positions but differed for leaf age (greater in immature than mature leaves; P\<0.05). Compounds that differed in Exp. 1 were represented about equally by mono- and sesquiterpenes, whereas compounds affected by leaf age were predominantly sesquiterpenes (only 3 of 32 were monoterpenes). Both leaf position and age affect terpene concentrations and sampling variability in this shrub.}, keywords = {chemical distribution, leaf age, terpenes}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James and D.M. Anderson} } @proceedings {JRN54546, title = {Deriving shrub heights from high resolution stereo-pair aerial imagery: An application for broad-scale rangeland monitoring}, volume = {p. 0114}, year = {2011}, month = {01/2012}, publisher = {Society for Range Management}, address = {Spokane, Washington}, abstract = {Vertical vegetation structure in rangeland ecosystems can be a valuable indicator for monitoring rangeland health or progress toward management objectives because of its importance for assessing riparian areas, post-fire recovery, wind erosion, and wildlife habitat. Federal land management agencies are directed to monitor and manage rangelands at landscapes scales, but traditional field methods for measuring vegetation heights are often too costly and time consuming to apply at these broad scales. Emerging remote sensing techniques (e.g., LiDAR or synthetic aperture radar) are too expensive, require specialized sensors, or are not of high enough resolution for broad-scale application. An alternative remote sensing approach is to measure vegetation heights from digital stereo aerial photographs. The purpose of this study was to test the feasibility and accuracy of estimating shrub heights from highresolution (HR, 3-cm ground sampling distance) digital stereo-pair aerial images. Overlapping HR imagery was taken in March 2009 near Lake Mead National Recreation Area and 5 cm resolution digital terrain models (DTMs) were created for five 2,500 m2 test plots. Average shrub heights from the DTMs were compared to field measurements from the test plots, yielding results suggesting this technique has potential for estimating shrub heights. However, compared to typical field methods, average shrub heights from the DTMs were consistently underestimated because the resolution of the imagery was not able to capture fine branches measured in the field. Through the use of statistically derived correction factors, though, vegetation heights from HR DTMs could be a valuable technique for broad-scale rangeland monitoring needs.}, author = {Jeffrey K. Gillan and Jason W. Karl and Danielle Duni} } @article {49951, title = {DIMA quick start; database for inventory, monitoring and assessment}, year = {2011}, pages = {1-37}, publisher = {USDA ARS Jornada Experimental Range}, abstract = {The Database for Inventory, Monitoring and Assessment (DIMA) is a highly-customized Microsoft Access database for collecting data electronically in the field and for organizing, storing and reporting those data for monitoring and assessment.\  While DIMA can be used for any number of different monitoring data collection needs, it is particularly well suited to collecting data for the BLM\’s Assessment, Inventory and Monitoring (AIM) Strategy following the BLM Core Indicators and Methods.\  It is much easier to use DIMA if you have a basic understanding of what data base being stored in it and how they are organized.}, url = {/files/bibliography/11-027.pdf}, author = {Jason W. Karl and Jeffrey E. Herrick and Ericha Courtright} } @article {49967, title = {Dust: small-scale processes with global consequences}, journal = {EOS Transactions, American Geophysical Union}, volume = {92}, year = {2011}, pages = {241-243}, abstract = {

[1] Desert dust, both modern and ancient, is a critical component of the Earth system. Atmospheric dust has important effects on climate by changing the atmospheric radiation budget, while deposited dust influences biogeochemical cycles in the oceans and on land. Dust deposited on snow and ice decreases its albedo, allowing more light to be trapped at the surface, thus increasing the rate of melt and influencing energy budgets and river discharge. In the human realm, dust contributes to the transport of allergens and pathogens and when inhaled can cause or aggravate respiratory diseases. Dust storms also represent a significant hazard to road and air travel. Because it affects so many Earth processes, dust is studied from a variety of perspectives and at multiple scales, with various disciplines examining emissions for different purposes using disparate strategies. Thus, the range of objectives in studying dust, as well as experimental approaches and results, has not yet been systematically integrated. Key research questions surrounding the production and sources of dust could benefit from improved collaboration among different research communities. These questions involve the origins of dust, factors that influence dust production and emission, and methods through which dust can be monitored.

}, keywords = {desert dust, dust emissions, remote sensing, small-scale processes}, doi = {10.1029/2011EO290001 }, url = {files/bibliography/JRN00562.pdf}, author = {Gregory S. Okin and Joanna E. Bullard and Reynolds, R. L. and Ballantine, J.-A. C. and Schepanski, K. and Todd, M. C. and Jayne Belnap and Matthew C. Baddock and Thomas E. Gill and M. Miller} } @article {49976, title = {Disturbance regimes and ecological responses across sites}, year = {2011}, keywords = {cross-site comparisons, disturbance regimes, ecological responses, ecological systems, global change}, author = {Debra C. Peters and Ariel E. Lugo and F.S. Chapin III and Tepley, A. J. and F. J. Swanson} } @proceedings {49996, title = {Discriminatory power of MicroResp analyses across variable spatial scales in semiarid ecological zones}, year = {2011}, month = {08/2011}, publisher = {Nature Proceedings}, address = {Bad Nauheim, Germany}, abstract = {ndirect assessment of enzymatic activity potential via substrate induced respiration is a common tool used to evaluate variability in soil microbial activity induced by environmental or management variables. The MicroResp\™ method for total soil sample catabolic profiling has been employed to estimate divergence in microbial activities under contrasting conditions. Here we evaluate the potential for the method to discriminate across samples exposed to similar ecological conditions at distinct geographical locations, and across samples exposed to distinct soil management conditions. Samples used in this report came from four spatially distinct arid or semi arid locations in New Mexico, USA and Jordan. For all scales of comparison, similar conditions such as rhizosphere and non-rhizosphere soils, disturbance levels, soil depth and distance from plants were considered as factors. Catabolic profiles vary within and between sampling locations as a function of soil characteristics as induced by proximity to plants, plant species, sampling depth and land disturbance.}, doi = {http://dx.doi.org/10.1038/npre.2011.6204.1}, url = {/files/bibliography/11-030.pdf}, author = {Tahtamouni, Mohammad E. and Unc, Adrian and M.E. Lucero and Sa{\textquoteright}eb Khresat} } @conference {JRN54457, title = {Degraded states, novel ecosystems, or reconfigured landscapes: How should we view ecosystem change in a changing world?}, booktitle = {63rd Society for Range Management Annual Meetings}, year = {2010}, month = {02/2010}, publisher = {Sociiety for Range Management}, organization = {Sociiety for Range Management}, address = {Denver, CO}, abstract = {

Climate change is predicted to cause gradual warming and changes in the amount and distribution of rainfall. Thus, the default assumption should be that attributes of rangelands will change, rather than stay as they have been. The talks in this symposium have described what may happen to rangeland communities and why. Here, we explore how managers and policymakers might evaluate and react to predicted ecosystem change. First, ecosystem change can be viewed as degradation to an alternative state in which the risks of transition have increased but managerial attention can preserve functions, and some essential services, of the original ecosystem. Second, ecosystem change may inevitably produce novel ecosystems with combinations of species, functions, and ecosystem services that are distinct from ancestral ecosystems (particularly via invasive species) and that should be accepted for what they are. Third, ecosystem change may reconfigure the relationships among attributes that existed in the ancestral landscape, such that adaptive management can be used to promote a combination of new and previously emphasized functions and services in different parts of a landscape. Depending on the nature of baseline, climate-driven ecosystem responses and managers{\textquoteright} ability to influence them, each of these reactions should be considered. We conclude by exploring how these distinct scenarios might be captured in state-and-transition models. Abstract $\#$ SYM-109.

}, author = {Brandon T Bestelmeyer and Joel R. Brown} } @conference {50039, title = {The devil is in the details: overcoming the challenge of implementing consistent ecosystem indicators for cross-scale ecosystem understanding}, booktitle = {7th International Conference on Ecological Informatics (ISEI7)}, year = {2010}, month = {12/2010}, address = {Ghent, Belgium}, abstract = {Addressing environmental challenges requires understanding and monitoring of ecosystem responses to direct and indirect human impacts from local to global scales. Because it is generally not possible to sample at a sufficiently high density across a large spatial extent with a single data program, achieving a cross-scale understanding of ecosystem responses to global change requires the collection and synthesis of data from a number of sources, including broad-scale monitoring efforts, sensor arrays, networks of long-term research sites, and locally-collected datasets. Previous studies have highlighted the importance of data accessibility, metadata and data ontologies, database structures, and scientific workflows for discovering and integrating data. However, two critical aspects of data semantics (consistency in definitions of basic ecosystem indicators observational units, compatibility of methods of measurement) can greatly affect the ability to combine datasets measuring the same attribute. Consistency and compatibility among datasets can be achieved if there is general agreement and coordination on how observational units are defined and measured. While the need for standard indicators and methods is broadly agreed upon, the coordination and implementation of such standards has proved challenging. We review different approaches to achieving consistency and compatibility in ecological data along a continuum of observer control, from completely dispersed, independent data collection without standard protocols across sites (e.g., U.S. Long Term Ecological Research sites) to a mix of independent and standardized data collections (e.g., EcoTrends Project) and then completely centralized data collection and storage according to formal protocols (e.g., U.S. Natural Resource Inventory, National Climate Data Center). In the context of a national, multi-scale monitoring effort being developed for the U.S. Bureau of Land Management, we then consider external factors that have necessitated adoption of standard indicators and methods and the impact these are having on the degree to which datasets can be integrated to answer questions across a range of spatial scales. Finally, we provide recommendations for implementing minimum standard indicators and methods for ecological data collection that can be supplemented for local needs. Improving data consistency and compatibility through standard indicators and methods will support a broad-scale framework for synthesis of ecological information that is necessary to link different sources of data across scales to address pressing environmental challenges at scales at which they are occurring.}, author = {Jason W. Karl and Debra C. Peters} } @conference {JRN54455, title = {Differences in MODIS EVI-based rainfall use efficiency among ecological states of the northern Chihuahuan Desert}, booktitle = {63rd Society for Range Management Annual Meetings}, year = {2010}, month = {02/2010}, publisher = {Sociiety for Range Management}, organization = {Sociiety for Range Management}, address = {Denver, CO}, abstract = {

Shrub encroachment into grasslands of the northern Chihuahuan Desert has resulted in often dramatic and geographically extensive changes in vegetation composition and soil structure. The nature of these transformations and their dependencies on soil characteristics have been largely conceptualized in state and transition models. Reduced perennial plant cover and heightened erosion in shrub interspaces suggests a reduced capacity for shrub-dominated sites to convert rainfall, typically the limiting resource in arid ecosystems, into plant biomass. We examined this hypothesis in the Jornada Basin, New Mexico using the MODIS Enhanced Vegetation Index (EVI) as a surrogate for primary productivity. The time frame of the study (2002-2008) coincided with a regional transition from below to above normal rainfall, providing an opportunity to assess vegetation response to increased moisture availability. A relatively dense network of rain gauges on the Jornada Experimental Range and Chihuahuan Desert Rangeland Research Center allowed for satisfactory rainfall interpolation at the scale of MODIS 250 meter imagery. Problems arising from spatial heterogeneity in soil brightness and vegetation structure were reduced by computing linear relationships between annual integrated EVI (I-EVI) and rainfall on a per-pixel basis across the study area. The coefficient of determination (r2), slope and intercept of these regressions were then mapped as a means of assessing spatial patterns in rainfall use efficiency (RUE). Here, we illustrate the results of this approach. We evaluate RUE metrics against ground-based ecological state classifications and satellite-derived shrub cover estimates, and we show that temporal, pixel-based assessments of RUE offer valuable insight into the functioning of Chihuahuan Desert vegetation states, despite some common problems associated with interpreting vegetation indices in ecosystems with low and diverse plant cover.

}, author = {Jebediah C. Williamson and Brandon T Bestelmeyer} } @conference {50069, title = {Does woody plant encroachment increase ecosystem carbon stocks?}, booktitle = {Ecological Society of America 94th Annual Meeting}, year = {2009}, month = {August 2009}, pages = {PS 46-59}, address = {Albuquerque, NM, August 2-7, 2009}, abstract = {Drylands account for ~30-35\% of terrestrial primary production and are an important component of the global carbon cycle. Changes in dryland vegetation thus have implications for carbon uptake and storage. One widely observed change is the conversion of grasslands to shrublands and woodlands. Although regarded as significantly impacting the North American terrestrial carbon sink, estimates are highly uncertain. Shrub proliferation typically increases aboveground carbon pools. However, the majority of organic carbon in drylands resides as soil organic carbon (SOC). Reports of impacts of shrub proliferation on SOC are equivocal and range from substantial decreases to no net change to substantial increases.~We quantified changes in ecosystem carbon pools accompanying shrub (Prosopis velutina) proliferation in Arizona grasslands. Size and location of P. velutina plants in a 0.4 ha area were determined in 1932, 1948 and 2006. Aboveground C mass of P. velutina was calculated using allometric equations. SOC (0-20 cm) was quantified along bole-to-dripline transects for a range of shrub sizes. A predictive model of SOC mass as a function of shrub size (basal diameter) was developed, applied to each individual on each date and summed across all shrubs to estimate aboveground shrub and SOC stocks over time (g C m-2).~Results/Conclusions: Aboveground shrub C mass increased from 1932 (217 g m-2) to 1948 (362 g m-2) and then declined to 224 g m-2 in 2006 as a result of an herbicide application in 1965/66. The herbicide application ostensibly shifted the population structure to smaller plants (mean plant canopy area declined from 6.3 [1948] to 3.8 m2 [2006]), but was coupled with an increase in plant density (323 ha-1 in 1948; 443 ha-1 in 2006).~SOC comprised 72-81\% of the soil plus aboveground shrub carbon pool. In the absence of shrubs, SOC mass was 896 g C m-2; accounting for the influence of shrubs increased SOC mass to 912 g C m-2 in 1932 and to 940 kg C m-2 by 2006, a 3\% increase despite the herbicide application. Our results confirm Prosopis encroachment into semi-arid grasslands will increase carbon storage in both the aboveground and near-surface SOC pools. Because SOC accumulation increases with tree size, historically invaded landscapes with larger individuals will be greater carbon sinks than more recently invaded landscapes.~ Land management practices (brush control) can dramatically reduce the aboveground C pool, but it recovers fairly quickly, with a potentially lagged, but poorly understood impact on the SOC pool.}, keywords = {cargon, terrestrail;}, author = {Steven R. Archer and Heather L. Throop and Dawn M. Browning and K. Predick} } @conference {50082, title = {Does livestock grazing influence spatial patterns of woody plant proliferation?}, booktitle = {Ecological Society of America Abstracts}, year = {2009}, month = {August 2009}, pages = {COS 127-10}, abstract = {Patterns of woody plant proliferation in grasslands and savannas influence rates of erosion, spread of disturbance, and nutrient pools.~ Spatial pattern is the outcome of plant dispersal, recruitment, competition/facilitation, and disturbance. We quantified effects of livestock grazing, a widely cited driver of shrub encroachment, on the spatial patterns of velvet mesquite (Prosopis velutina) distribution and recruitment in southeastern Arizona. ~Field surveys of plant canopy size and location spanning 74 years (1932, 1948, and 2006) were conducted on areas grazed by livestock since the late 1800s and on areas protected from livestock since 1932.~ Point pattern analysis and Moran{\textquoteright}s I were used to quantify changes in distribution and spatial autocorrelation over time.}, keywords = {erosion, grasslands, nutrient, savannas, spatial pattern}, author = {Dawn M. Browning and Steven R. Archer and Janet Franklin and Guertin, D. P.} } @article {50124, title = {The Desert Project--An analysis of aridland soil-geomorphic processes}, year = {2009}, note = {//USDA//NONE//entered 06/22/2010; pdf availableProCite field[12]: In File (02/05/2010)}, month = {2009}, pages = {76}, institution = {New Mexico Agricultural Experimental Station}, type = {pp}, address = {Las Cruces, New Mexico}, abstract = {In this report, soil-geomorphic maps, cross sections, three-dimensional diagrams, tables of soil characterization data, and photographs are used to illustrate a variety of soil-geomorphic features in the Desert Project.}, keywords = {calcium carbonate, caliche, climate, hydrogeology, paleoclimate, paleogeomorphology, report, soil chronology, soil taxonomy, soil, buried charcoal, soil, geomorphology, soil, radiocarbon dating, soil, sedimentation, soil, volcanic ash, soil-geomorphic relations}, isbn = {Bulletin 798}, url = {http://aces.nmsu.edu/pubs/research/weather_climate/BL798.pdf}, author = {Curtis H. Monger and L. H. Gile and J. Hawley and R. Grossman} } @article {50126, title = {Do changes in connectivity explain desertification?}, journal = {BioScience}, volume = {59}, number = {3}, year = {2009}, month = {March 2009}, pages = {237-244}, abstract = {Desertification, broad-scale land degradation in drylands, is a major environmental hazard facing inhabitants of the world{\textquoteright}s deserts as well as an important component of global change. There is no unifying framework that simply and effectively explains different forms of desertification. Here we argue for the unifying concept that diverse forms of desertification, and its remediation, are driven by changes in the length of connected pathways for the movement of fire, water and soil resources. Biophysical feedbacks exist that increase the length of connected pathways explaining the persistence of desertified landscapes around the globe. Management of connectivity in the context of environmental and socioeconomic change is essential to understand, and potentially reverse, the harmful effects of desertification.Desertification, broad-scale land degradation in drylands, is a major environmental hazard facing inhabitants of the world{\textquoteright}s deserts as well as an important component of global change. There is no unifying framework that simply and effectively explains different forms of desertification. Here we argue for the unifying concept that diverse forms of desertification, and its remediation, are driven by changes in the length of connected pathways for the movement of fire, water and soil resources. Biophysical feedbacks exist that increase the length of connected pathways explaining the persistence of desertified landscapes around the globe. Management of connectivity in the context of environmental and socioeconomic change is essential to understand, and potentially reverse, the harmful effects of desertification.}, keywords = {connectivity, desertifiction, erosion, fire, vegetation dynamics}, url = {/files/bibliography/09-007.pdf}, author = {Gregory S. Okin and A.J. Parsons and John Wainwright and Jeffrey E. Herrick and Brandon T Bestelmeyer and Debra C. Peters and E.L. Fredrickson} } @article {50162, title = {Do symbiotic microbes have a role in plant evolution, performance and response to stress?}, journal = {Communicative and Integrative Biology}, volume = {1}, number = {1}, year = {2008}, month = {September 1, 200}, pages = {69-73}, abstract = {

Vascular plants have been considered as autonomous organisms especially when their performance has been interpreted at the genome and cellular level. In reality, vascular plants provide a unique ecological niche for diverse communities of cryptic symbiotic microbes which often contribute multiple benefits, such as enhanced photosynthetic efficiency, nutrient and water use and tolerance to abiotic and biotic stress. These benefits are similar to improvements sought by plant scientists working to develop ecologically sustainable crops for food, fiber and biofuels. Native desert plants include a community of indigenous endosymbiotic fungi that are structural components with cells, tissues, cell cultures, and regenerated plants. These fungi regulate plant growth and development and contribute genes and natural products that enable plants to adapt to changing environments. A method developed for transferring these endophytes from cell cultures to non-host plants promises to be a revolutionary approach for the development of novel plant germplasm and has application in the field of plant biotechnology.

}, keywords = {cryptic, Symbiotic, vascular}, url = {/files/bibliography/08-033.pdf}, author = {J.R. Barrow and M.E. Lucero and I. Reyes-Vera and Kris Havstad} } @article {50185, title = {Does drought control emergence and survival of grass seedlings in semi-arid rangelands? An example with a Patagonian species}, journal = {Journal of Arid Environments}, volume = {72}, year = {2008}, note = {//OTHER//OTHER//entered 06/02/2008 per DEP}, month = {2008}, pages = {161-174}, keywords = {article, drought, grass seedling, grass seedling, emergence, grass seedling, survival, journal, rangeland}, author = {Cipriotti, P. A. and P. Flombaum and O. E. Sala and M. Aguiar} } @article {JRN54005, title = {Detecting land cover change at the Jornada Experimental Range, New Mexico with ASTER emissivities}, journal = {Remote Sensing of Environment}, volume = {112}, year = {2008}, month = {04/2008}, pages = {1730-1748}, chapter = {1730}, abstract = {

Multispectral thermal infrared remote sensing of surface emissivities can detect and monitor long term land vegetation cover changes over arid regions. The technique is based on the link between spectral emissivities within the 8.5\–9.5\ \μm interval and density of sparsely covered terrains. The link exists regardless of plant color, which means that it is often possible to distinguish bare soils from senescent and non-green vegetation. This capability is typically not feasible with vegetation indices. The method is demonstrated and verified using ASTER remote sensing observations between 2001 and 2003 over the Jornada Experimental Range, a semi-arid site in southern New Mexico, USA. A compilation of 27 nearly cloud-free, multispectral thermal infrared scenes revealed spatially coherent patterns of spectral emissivities decreasing at rates on the order of 3\% per year with R2 values of \∼\ 0.82. These patterns are interpreted as regions of decreased vegetation densities, a view supported by ground-based leaf area index transect data. The multi-year trend revealed by ASTER\&$\#$39;s 90-m resolution data are independently confirmed by 1-km data from Terra MODIS. Comparable NDVI images do not detect the long-term spatially coherent changes in vegetation. These results show that multispectral thermal infrared data, used in conjunction with visible and near infrared data, could be particularly valuable for monitoring land cover changes.

}, keywords = {ASTER, emissivity, Jornada, land cover change, MODIS, Thermal infrared}, doi = {10.1016/j.rse.2007.08.020}, author = {A.N. French and T. J. Schmugge and Jerry Ritchie and A.F. Hsu and Jacob, F. and Ogawa, K.} } @conference {50210, title = {Do sampling methods differ in their utility for ecological monitoring? Comparison of line-point intercept, grid-point intercept, and ocular estimate methods}, booktitle = {Ecological Society fo America Abstracts}, year = {2008}, month = {August 3-8, 2008}, pages = {PS 83-125}, address = {Milwaukee, WI}, abstract = {This study compared the utility of three sampling methods for ecological monitoring based on: interchangeability of data (rank correlations), precision (coefficient of variation), cost (minutes/transect), and potential of each method to generate multiple indicators. Species richness and foliar cover by species were measured for each method on four transects (70 m) in 15 sites (three in each of five plant communities) in the northern Chihuahuan Desert. Randomized species accumulation curves and rank correlations of the three methods were conducted with these data.}, keywords = {ecological monitoring}, author = {Godinez-Alvarez, H. and Jeffrey E. Herrick and M. Mattocks and David P. Toledo} } @conference {50228, title = {Dynamic soil property reference values and soil resilience: Keys to developing innovative, sustainable solutions for American agriculture?}, booktitle = {Geological Society of America}, series = {2008 Joint Meetings}, year = {2008}, month = {10/2008}, pages = {679-5}, address = {Houston, TX}, abstract = {

Farmers, ranchers, conservationists and other land managers can benefit from four types of soil information when developing new management systems and deciding where to apply currently available systems: (1) values for relatively static soil properties and relationships to plant growth, (2) values for relatively dynamic soil properties that have a significant effect on soil functions such as supporting plant growth, (3) reference values for the potential range of variability for these dynamic soil properties for their soil(s), and (4) information on resistance to degradation and the extent and rate of recovery (resilience) that should be expected in response to a change in management or other perturbation to their soil(s). The first type of information is widely available through existing soil surveys. The second can be easily measured. The third would be generated through the implementation of the strategic plan for integrating dynamic soil properties into the National Cooperative Soil Survey. The value of this dataset would continue to increase with the number and diversity of management systems and/or ecological states included. Increased availability of standardized, quantitative data on the current range of variability for their soil would help farmers define realistic targets, while providing baseline values for innovative land managers to attempt to exceed. This has the potential to extend the benefits of competition beyond yield maximization. The fourth type of information (resilience) would help land managers increase their ability to anticipate and avoid degradation, while targeting limited resources to target opportunities to promote recovery. This paper will illustrate the points above using several short- and long-term datasets.

}, keywords = {reference, resilience, soil, value}, author = {Jeffrey E. Herrick and Brandon T Bestelmeyer and Joel R. Brown} } @proceedings {50262, title = {Development of an operational UAV / Remote sensing capability for rangeland management}, year = {2008}, month = {April 2008}, pages = {CDROM 9 pp.}, abstract = {Rangeland comprises approximately 70\% of the Earth{\textquoteright}s land surface area. Much of this vast space is in very remote areas with difficult access. Unmanned Aerial Vehicles (UAVs) have great potential for rangeland management applications. UAVs have several advantages over satellites and piloted aircraft: they can be deployed quickly and repeatedly; they are less costly and safer than piloted aircraft; they are flexible in terms of flying height and timing of missions; and they can obtain imagery at sub-decimeter resolution. This hyperspatial imagery allows for observation of individual plants, patches, gaps, and patterns over the landscape not previously possible. Our experiments have shown that this capability, from an off-the-shelf small-UAV is directly applicable to operational agency needs for evaluating rangeland health. At the Jornada Experimental Range in southern New Mexico, USA, ongoing research is aimed at determining the utility of UAVs for rangeland mapping and monitoring. For use by operational agencies to carry out their mandated responsibilities, various requirements must be met: an affordable and reliable platform; a capability for autonomous, low altitude flights; takeoff and landing in minimal size and rugged areas; and an easily applied data analysis methodology. There are a number of image processing and orthorectification challenges; image distortion associated with inexpensive, consumer grade digital cameras; difficulty of detecting sufficient ground-control points in small area photos; accuracy of exterior information (X.Y,Z, roll, pitch, and heading); and the large number of images that can be collected. Recent results of this research are presented.}, keywords = {imagery, remote sensing, UAV, unmanned aerial vehicle}, url = {/files/bibliography/08-048.pdf}, author = {A. Rango and Andrea S. Laliberte and Jeffrey E. Herrick and Craig Winters and Kris Havstad} } @conference {50272, title = {Does energy flux determine ant diversity? A case study in an arid ecosystem}, booktitle = {93rd Ecological Society of America Annual Meetings}, year = {2008}, month = {August 3, 2008}, pages = {PS 71-14}, abstract = {Ants are highly diverse, widespread, and abundant organisms playing important roles in ecosystem functioning. For these reasons, it is useful to know what structures their diversity. Biodiversity is ultimately constrained by energy availability and the relationship between energy and diversity has been considered at global scales. Energy flux measured as net primary productivity (NPP), however, also varies considerably at landscape scales. In this work, we asked if patterns of ant diversity within a landscape can be predicted by variation in energy flux. To answer this question, we studied ant biodiversity and its relationship to NPP in the Chihuahuan Desert. This study was carried out at the Jornada Basin in southern New Mexico, in a portion of about 100,000 ha that comprises a variety of soils and geomorphology that result in substantial differences in NPP. We measured the peak standing crop biomass (as a proxy for NPP) of 20 sites that comprise 5 different types of vegetation states (grasslands, shrublands and ecotones between them), as well as the richness, abundance and biomass of ants.}, keywords = {ant, diversity, energy}, author = {Rio-Casanova, L. and Brandon T Bestelmeyer} } @article {50281, title = {Data-driven identification of group dynamics for motion prediciton and control}, journal = {Journal of Field Robotics}, volume = {25}, number = {6-7}, year = {2008}, month = {June 1, 2008}, pages = {305-324}, abstract = {

A distributed model structure for representing groups of coupled dynamic agents is proposed, and the Least Squares method is used for fitting model parameters based on measured position data. The difference equation model embodies a minimalist approach, only incorporating factors essential to the movement and interaction of physical bodies. The model combines effects from an agent\’s inertia, interactions between agents, and interactions between each agent and its environment. GPS tracking data were collected in field experiments from a group of three cows and a group of ten cows over the course of several days using custom-designed, head mounted sensor boxes. These data are used with the Least Squares method to fit the model to the cow groups. The modeling technique is shown to capture overall characteristics of the group as well as attributes of individual group members. Applications to livestock management are described, and the potential for surveillance, prediction, and control of various kinds of groups of dynamical agents are suggested.

}, keywords = {control, data-driven, journal, Least Squares, motion prediction}, doi = {10.1002/rob.20243}, url = {/files/bibliography/08-014.pdf}, author = {Schwager, M. and Deweiler, C. and Vasilescu, L. and D.M. Anderson and D. Rus} } @proceedings {50301, title = {Differences in rangeland use pattterns of young cows with different stress coping styles: Preliminary results}, year = {2008}, month = {July 18, 2008}, pages = {23-26}, address = {Corona, NM}, abstract = {Individuals in most animal groups exhibit consistent behavioral differences within or across situations (feeding, mating, predator avoidance, etc.) known as behavioral syndromes (Sih et al. 2004). Proactive (more nervous) vs. reactive (calmer) behavioral syndromes have been observed in many animal species and have been shown to influence how individuals cope with stress (Koolhaas et al. 1999). We investigated the relationships between stress coping styles, patterns of rangeland use, and performance of thirty six 3-year-old cows during two consecutive calving seasons (2006-07). We found that calmer cows (classified as reactive) spent more time at water, explored smaller areas in any given day, had lower body weights, longer postpartum anestrous periods, and weaned lighter calves than cows classified as proactive (more nervous cows). Because our results are based on a limited number of animals which belong to a fairly docile herd, they should be considered preliminary. Further work investigating these relationships is underway.}, keywords = {Corona, proceedings, stress}, url = {/files/bibliography/08-028.pdf}, author = {Wesley, R.L. and Andr{\'e}s F. Cibils and Pollak, E.R. and S.H. Cox and Mulliniks, J.T. and M.K. Petersen and E.L. Fredrickson} } @article {50304, title = {Do litter decomposition and nitrogen mineralization show the same trend in the response to dry and wet years in the Patagonian steppe?}, journal = {Journal of Arid Environments}, volume = {72}, year = {2008}, note = {//OTHER//LTER V//entered 06/02/2008 per DEP; updated 06/26/2009 [pdf obtained; abstract added]}, month = {2008}, pages = {687-695}, abstract = {

In arid environments, dry and wet years have similar number of small rainfall events but wet years result from the occurrence of a few large rainfall events. What are the implications of these different precipitation patterns on ecosystem functioning? Here, we examined the differential response of soil processes to wet and dry years. Specifically, we assessed litter decomposition and soil N mineralization responses to precipitation excess in the Patagonian steppe, and compared with responses to drought conditions previously reported for this ecosystem.Litter decomposition rates did not differ significantly between simulated wet year and control, while litter decomposition rates decreased under a drought of a similar absolute magnitude. We hypothesize that decomposition rate in this ecosystem may be driven more by number of rainfall events than by total precipitation amount. Net nitrification increased in the simulated wet year but only for a short period of time. Moreover, irrigation positive effects on nitrification were offset by negative effects on net ammonification. Consequently, net N mineralization was not affected by water availability. Our results suggest that the different microorganisms responsible of nitrification and ammonification have differential sensitivity to water availability and that the environmental controls might be overwhelmed by substrate availability in longer time scales. {\textcopyright} 2007 Elsevier Ltd. All rights reserved.

}, keywords = {article, journal, litter decomposition, Patagonian steppe, nitrogen mineralization, Patagonian steppe, Patagonian steppe}, doi = {10.1016/j.jaridenv.2007.09.005}, url = {files/bibliography/JRN00496.pdf}, author = {Laura Yahdjian and O. E. Sala} } @article {50313, title = {Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland-shrubland ecotones}, journal = {Journal of Vegetation Science}, volume = {18}, year = {2007}, month = {March 1, 2007}, pages = {363-370}, abstract = {Does shrub invasion at ecotones indirectly limit grass establishment by increasing mammalian seedling herbivory, Chihuahuan Desert, New Mexico? We tested the hypothesis that herbivore-related mortality of seedlings of the dominant perennial grass Bouteloua eriopoda would be highest in shrub-dominated portions of grassland-shrubland ecotones. We tested the hypothesis in two Chihuahuan Desert sites featuring similar shrub encroachment patterns but different shrub species, grass cover, and different abundances of small mammals. Within each site we transplanted B. eriopoda seedlings to grass-dominated, middle, and shrub-dominated positions of replicate ecotones during the time of year (mid-summer) when they would naturally appear and monitored seedling fates. We estimated population size/activity of putative small mammal herbivores. Seedlings were killed by mammals in greater number in shrubland than in grassland or middle ecotone positions at the site withlarge herbivore numbers. At the site with low herbivore numbers, most seedlings were killed in middle ecotone positions. The abundance patterns of herbivores did not parallel patterns of seedling herbivory across the ecotones or between sites. Seedling herbivory is an improtant process and is related to vegetation composition, but the mechanisms underlying the relationship are not clear. We speculate that variation in small mammal foraging behvior may contribute to seedling herbivory patterns. Restoration strategies in the Chihuahuan Desert need to account for the abundance and/or behavior of native herbivores.}, keywords = {alternative state, Bouteloua eriopoda, Chihuahuan Desert, desertifiction, Dipodomys, foraging behavior, Lepus californicus, restoration, small mammal}, url = {/files/bibliography/07-005.pdf}, author = {Brandon T Bestelmeyer and Khalil, N.I. and Debra C. Peters} } @proceedings {50360, title = {Differences in volatile profiles between populations of Ceratoides lanata var. subspinosa (Rydb.) J.T. Howell}, volume = {RMRS-P-47}, year = {2007}, month = {August 10-12, 20}, pages = {142-146}, publisher = {USDA Forest Service, Rocky Mountain Research Station}, address = { Lubbock, TX}, abstract = {Ceratoides lanata (Rydb.) J.T. Howell, common winterfat, is valued for its nutrient content and palatability to livestock. However, the subspecies Ceratoides lanata var. subspinosa (Rydb.) J.T. Howell, first described in the Mojave desert, is considered unpalatable. This characterization has been supported by data from livestock grazing studies at the Jornada Experimental Range in southern New Mexico. Curiously, observation of subspinosa revealed several populations in central New Mexico which were heavily grazed. Volatile terpene profiles have frequently been associated with differences in palatability in various plant species. To determine whether differences in volatile profiles between subspinosa populations would correlate with apparent differences in palatability, plants from 13 populations of subspinosa were collected in the fall of 2000. Volatile analysis of ground shoot samples using solid-phase microextraction and gas chromatography-mass spectroscopy consistently identified 33 compounds. Limonene, myrcene, and 3-carene were the most abundant compounds in all populations, comprising 81\% and 85\% of the volatiles detected in heavily grazed and ungrazed plants, respectively. This is thought to be the first time C. lanata subspinosa volatiles have been described. Compounds present in at least half of either the heavily grazed or ungrazed plants were subjected to a stepwise discriminate analysis of relative quantities. The analysis identified a subset of 14 chromatographic peaks (myrcene, 3-hexenol, 3-carene, AR-curcumene, limonene, n-hexanol, p-cymene, a mixture thought to contain alpha-pinene, alpha-thujene, and tricyclene, a mixture thought to contain n-decanal, and five unknowns) which may distinguish between palatable and unpalatable phenotypes. When a discriminate rule based on these chemicals was applied to chemical data from individual plants at all sites, none of the plants were misclassified. The possibility that these varied oil profiles may be used to distinguish palatable from unpalatable phenotypes is discussed. http://www.fs.fed.us/rm/pubs/rmrs_p047/rmrs_p047_142_146.pdf}, keywords = {ceratoides, lanata, populations, subspinosa, Volatile}, url = {/files/bibliography/07-022.pdf}, author = {M.E. Lucero and Richard E. Estell and D.M. Anderson and E.L. Fredrickson and M.D. Remmenga}, editor = {R. E. Sosebee and Wester, D.B. and Britton, C.M. and McArthur, E.D. and S.G. Kitchen} } @conference {50375, title = {Development of a UAV rangeland remote sensing capability}, booktitle = {Proceedings Grazing Lands Conservation Initiative. Third National Conference on Grazing Lands}, year = {2007}, note = {ProCite field[23]: December 10-13, 2006}, month = {May 1, 2007}, pages = {319}, address = {St. Louis, Missouri}, abstract = {Starting in 2000, experiments have been conducted at the Jornada Experimental Range near Las Cruces, NM to evaluate the utility of Unmanned Aerial Vehicles (UAVs) for applications on arid rangelands. When compared to all types of remote sensing research ongoing at Jornada and other locations, UAVs have the following advantages: flexible timing of missions, high resolution images, repeat coverage for monitoring, lower cost and safer operation than piloted aircraft, and the system can be operated by one individual, if necessary. The UAVs fill a niche in remote sensing of rangeland between ground-based photography and piloted aircraft. The high resolution possible (less than 5 cm) allows observations of individual plants, patches, gaps, and patterns over the landscape not previously possible. This capability has immediate application for assessment of rangeland health and ecosystem change. The low operating cost and simple data products make the system logical for transfer to operational agencies for collection of data in specific locations in vast public land areas in a timely manner.}, keywords = {applications, remote sensing, UAV}, author = {A. Rango and Andrea S. Laliberte and Jeffrey E. Herrick} } @proceedings {50383, title = {Data-driven identification of group dynamics for motion prediction and control}, year = {2007}, abstract = {A decentralized model structure for representing groups of coupled dynamic agents is proposed, and the Least Squares method is used for fitting model parameters based on observed position data. The physically motivated, difference equation model combines effects from agent dynamics, interactions between (probably should have been among rather than between since n=3) agents, and interactions between (probably should have been among rather than between since n=3) each agent and its environment. The technique is implemented to identify a model for a group of three cows using GPS tracking data. The model is shown to capture overall characteristics of the group as well as attributes of individual group members. Applications to surveillance, prediction, and control of various kinds of groups of dynamical agents are suggested.}, keywords = {control, data-driven, dynamic, prediction, proceeding, proceedings}, author = {Schwager, M. and D.M. Anderson and D. Rus} } @article {50387, title = {Differentiation of semi-arid vegetation types based on multi-angular observations from MISR and MODIS}, journal = {International Journal of Remote Sensing}, volume = {28}, year = {2007}, month = {11/2007}, pages = {1419-1424}, abstract = {Mapping accurately vegetation type is one of the main challenges for monitoring arid and semiarid grasslands with remote sensing. The multi-angle approach has been demonstrated to be useful for mapping vegetation types in deserts. This letter presents a study on the use of directional reflectance derived from two sensor systems, using two different models to analyze the data and two different classifiers as a means of mapping vegetation types. The multiangle Imaging SpecroRadiometer (MISR) and the Moderation Resolution Imaging Specroradiometer (MODIS) provide multi-spectral and angular, off-nadir observations. In this study, we demonstrate that reflectance from MISR observations and reflectance anisotropy patterns derived from MODIS observations are capable of working together to increase classification accuracy. The patterns are described by parameters of the Modified Rahman-Pinty-Verstraete and the RossThin- LiSparseMODIS bidirectional reflectance distribution function (BRDF) models. The anisotropy patterns derived from MODIS observations are highly complementary to reflectance derived from radiances observed by MISR. Support vector machine algorithms exploit the information carried by the same data sets more effectively than the maximum likelihood classifier.}, keywords = {bidirectional reflectance, classification, semi-arid land}, doi = {10.1080/01431160601085995}, url = {/files/bibliography/07-032.pdf}, author = {L. Su and M. Chopping and A. Rango and J. V. Martonchik and Debra C. Peters} } @conference {50408, title = {Determining vegetation coverage and changes in land use under the Quesungual slash and mulch agroforestry system}, booktitle = {Ecological Society of America Abstracts}, year = {2006}, month = {August 8, 2006}, pages = {Paper No. 62989}, address = {Memphis, TN}, abstract = {Land use throughout history has changed to suit the needs of the people, but just as the needs of the people have changed so should the methods employed to cultivate the land. As of 1985 producers in the municipality of Candelaria in the Department of Lempira in Honduras have been applying a locally developed method known as the Quesungual Slash and Mulch Agroforestry System (QSMAS). Candelaria is an area composed of slopes that commonly exceed 45 degrees, which results in high erosion rates from cultivated fields. The QSMAS is an alternative to traditional slash and burn management, which requires extensive periods of time for recovery and contributes to soil erosion. The three main characteristics that distinguish the QSMAS from other traditional methods are the elimination of annual burning to allow accumulation of crop residue, management of native trees to provide a partial canopy that encourages rapid forest regeneration during fallow, and zero tillage in order to maintain soil structure and high mulch coverage. QSMAS provides the ability to reduce the time required by land to recover under fallow, which in turn may reduce the amount of land that exceeds land degradation thresholds. An extensive amount of research has been done to understand the dynamics of the system at the plot level however; little research has analyzed the extent of adoption and the change in tree coverage due to adoption. The objectives of this project are 1) develop methodology to monitor the changes in land cover and land use through remote sensing imagery, and 2) apply these methods and ground-based measurements in a pilot study to quantify land coverage and land use in an area near the municipality of Candelaria. Preliminary analysis indicates difficulty in distinguishing parcels within the same region of Silvopastoral and those applying the QSMAS system.}, keywords = {agroforestry, Quesungual}, author = {Noemi Baquera and Jeffrey E. Herrick and M. Ayarza} } @article {50483, title = {Disentangling complex landscapes: new insights into arid and semiarid system dynamics}, journal = {BioScience}, volume = {56}, number = {6}, year = {2006}, month = {June 2006}, pages = {491-501}, abstract = {

Although desertification is a global phenomenon and numerous studies have provided information on dynamics at specific sites, spatial and temporal variation in response to desertification have led to alternative, and often controversial, hypotheses about the key factors that determine these dynamics. We present a new research framework that includes five interacting elements to explain these dynamics: (1) historical legacies, environmental driving variables, (3) a soil-geomorphic template, (4) horizontal and vertical transport vectors, and (5) redistribution of resources within and among spatial units. We offer a six-step operational approach that is applicable to many landscapes, and illustrate its utility for understanding present-day landscape organization, forecasting future dynamics, and making effective management decisions.

}, keywords = {alternative states, cross-scale interactions, desertification, feedbacks and thresholds, nonlinear dynamics}, doi = {10.1641/0006-3568(2006)56[491:DCLNII]2.0.CO;2}, url = {/files/bibliography/06-021.pdf}, author = {Debra C. Peters and Brandon T Bestelmeyer and Jeffrey E. Herrick and E.L. Fredrickson and Curtis H. Monger and Kris Havstad} } @article {50501, title = {Determinants of biodiversity change: ecological tools for building scenarios}, journal = {Ecology}, volume = {87}, year = {2006}, note = {//Other//LTER-V//entered 08/15/2007}, month = {2006}, pages = {1875-1876}, abstract = {

As defined in the recent Millenium Ecosystem Assessment (MA), biodiversity scenarios are "plausible alternative futures." They do not attempt to predict the precise future state of biodiversity, but rather they identify the consequences of the different paths that human society may follow for biodiversity. Scenarios are designed to assist decision makers by identifying costs and benefits, in terms of biodiversity, of alternative actions. Within the framework of the MA, the first stage in developing biodiversity scenarios was to identify the major drivers of biodiversity change in the next 50{\textendash}100 years. Land-use change, climate change, and nutrient enrichment were identified as the major drivers of biodiversity change in terrestrial and freshwater ecosystems. The next steps in constructing successful biodiversity scenarios are (1) assessing changes in drivers of different socioeconomic scenarios and (2) developing the algorithms that relate changes in drivers with changes in biodiversity. This Special Feature focuses on a key component of the second of these two steps: evaluating the current tools used by ecologists to develop scenarios based on changes in drivers of biodiversity change.

}, keywords = {article, biodiversity losses, biodiversity scenario, biodiversity, freshwater, biodiversity, river discharge, ecosystem services, global scenarios, journal, land-use change, model, MA, model, Millenium Ecosystem Assessment}, doi = {10.1890/0012-9658(2006)87\%5B1875:DOBCET\%5D2.0.CO;2}, url = {files/bibliography/JRN00441.pdf}, author = {O. E. Sala and R. B. Jackson} } @conference {50519, title = {Dynamic soil properties as a part of soil survey updates: illustration of the utility of the results from Arches National Park, Utah}, booktitle = {Western Society of Soil Science}, year = {2006}, month = {June 19, 2006}, abstract = {Sampling dynamic soil properties as a part of soil survey updates can provide results which meet user needs for recognizing soil and ecosystem change. We have identified and illustrated results for three potential needs: (1) an ability to detect a functionally significant difference in soil and ecosystem properties, (2) indicators that reflect functional differences in states on an ecological site, and (3) information for Ecological Site Descriptions. On park, as well as other lands, these results will facilitate an understanding of soil and ecosystem change. They can also be used to help design assessment and monitoring systems to address a variety of objectives including avoiding relatively irreversible human-induced changes to soil and ecosystem function. Although this pilot project focused on National Park lands, the methods and types of applications described in this paper can be utilized elsewhere.}, keywords = {Arches National Park, properties, soil, survey, Utah}, author = {J.P. Ward and A.J. Tugel and Jeffrey E. Herrick and M.D. Remmenga and Scott, C. and Truman, D. and Parslow, V. and Biggam, P. and C. Seybold and Benham, E.C.} } @conference {50526, title = {Directional Virtual Fencing (DVF TM) and its Impact on the Paradigm of Free-Ranging Animal Control}, booktitle = {Annual Conference of the Quivira Coalition Proceedings}, year = {2005}, month = {January 13-15, 2}, pages = {43}, publisher = {Quivira Caolition}, organization = {Quivira Caolition}, address = {Albuquerque, NM}, abstract = {Melding time-tested animal husbandary practices with cutting-edge technological advances and scientific breakthroughs coming from the disciplines of range, animal and ethological sciences provides an exciting platform from which to address free-ranging animal control in the 21st century. Decades of agricultural research have consistently revealed that flexibility is the first key in the proper management of complex biological systems. However, some tools that are available in rangeland management thwart flexibility and conventional fencing can sometimes fit into this category. Where legal as well as health and safety issues are of paramount concern in controlling animals, conventional fences are the tool of choice and will remain so well into the foreseeable future. However, where adaptive management is the goal, new tools such as Directional Virtual Fencing (DVFTM) will provide flexible animal control within a sound ecological framework. This methodology capitalizes on using animal behavior to attain spatial and temporal management goals focused on optimizing both plant and animal productivity. Workshop participants will learn what DVFTM is and how it differs from conventional methods of controlling free-ranging animals with particular emphasis on when, where and by whom DVFTM should be used when it becomes commercially available. Results from previous and ongoing studies in which Virtual Boundaries (VBTM) are being used to control animal groups will be discussed. A final focus will be to highlight researchable areas that currently remain unanswered concerning virtual animal control. The goal of this workshop is to expand our view of foraging from not only a process but to a potentially useful tool for carrying out rangeland remediation.}, keywords = {animals, directional virtual, fencing, free-ranging}, author = {D.M. Anderson} } @conference {50529, title = {Directional Virtual Fencing (DVF{\texttrademark}) and flerds}, booktitle = {58th Annual Meeting Society for Range Management}, year = {2005}, month = {February 5, 2005}, address = {Fort Worth, Texas}, abstract = {Controlling free-ranging animals is among the most challenging jobs a producer faces when managing livestock. Combining a practical understanding of animal behavior with emerging technologies provides opportunities to autonomously control the temporal and spatial location of cattle and sheep on arid rangelands without conventional fencing. Flerd refers to a mixed species group of sheep (flock) and cattle (herd) in which sheep consistently remain within line-of-sight of cattle even when given the opportunity to remain only with peers. This atypical sheep behavior results from modifying sheep behavior, preferably at an early age, through a process called bonding. Using Directional Virtual Fencing (DVFTM), which delivers audio sound and/or electric shock cues to either the right or left side of a cow{\textquoteright}s head, it was possible to contain cattle behind an activated Virtual Boundary (VBTM) that defines the perimeter of a Virtual Paddock (VPTM) using Global Positioning System (GPS) technology. Peer relationships among and between individual sheep affected flerd cohesiveness when combining bonded sheep with cows equipped with DVFTM devices. Preliminary results indicate three cows wearing DVFTM devices influenced the spatial location of 13 ewes and 1 wether.}, keywords = {cattle, Directional Virtual Fencing, flerds, free-ranging animals, sheep}, author = {D.M. Anderson and Nayak, P. and B. Nolen and E.L. Fredrickson and Richard E. Estell and C.S. Hale and Kris Havstad} } @article {50534, title = {Does desertification diminish biodiversity? Enhancement of ant diversity by shrub invasion in southwestern USA}, journal = {Diversity and Distributions}, volume = {11}, year = {2005}, month = {January 1, 2005}, pages = {45-55}, abstract = {

The conversion of desert grasslands to shrublands is a long-standing concern in the southwestern United States, but the effects of this change on native animals defy generalization. Here, I consider evidence that shrub invasion and encroachment, particularly that of honey mesquite (Prosopis glandulosa), has led to increasing ecological dominance and diversity of ants in general, as well as increases in specific native taxa. The effects of shrub invasion on ants were measured at two scales: (1) between Chihuahuan Desert landscapes that vary slightly in temperature and strongly in the dominance of mesquite, and (2) across variation in mesquite density occurring within a generally mesquite-dominated landscape. Ant richness and numerical dominance was measured at pitfall traps over 2 years and baits were used to assess ecological dominance across different temperatures. The mesquite-dominated Jornada site harbored four times the number of ant foragers found at the relatively \&$\#$39;pristine\&$\#$39; Sevilleta site with several ecologically-dominant taxa driving this pattern, especially Dorymyrmex bicolor. Species richness and ecological dominance was also greatest at the Jornada. Within the Jornada landscape, turnover in species composition was related to mesquite density, but local richness and abundance was unrelated to mesquite density. Coupled with the results of previous manipulative experiments and comparative studies, there is support for the notion that ant diversity is not negatively affected by shrub invasion but that several taxa prosper from it. The Jornada is uniquely saturated by dominant ant taxa, perhaps as a consequence of an overall high level of shrub availability that provides a reliable source of carbohydrate-rich plant exudates. This raises important questions about the relationship between environmental degradation, ecosystem productivity, and animal diversity.

}, doi = {10.1111/j.1366-9516.2005.00122.x}, url = {/files/bibliography/05-001.pdf}, author = {Brandon T Bestelmeyer} } @article {50548, title = {Desert grassland canopy arthropod species richness: temporal patterns and effects of intense, short-duration livestock grazing}, journal = {Journal of Arid Environments}, volume = {60}, number = {4}, year = {2005}, month = {March 1, 2005}, pages = {627-646}, abstract = {

Arthropods living in the canopies of two woody shrub species (a sub-shrub (Gutierrezia sarothrae) and a large shrub (Prosopis glandulosa)) and perennial grasses plus associated herbaceous species, were sampled on 18, 0.5 hectare plots in a Chihuahuan Desert grassland for five consecutive years. Mesquite shrubs were removed from nine plots, six plots were grazed by yearling cattle in August and six plots were grazed in February for the last 3 years of the 5 year study. Arthropod species richness ranged between 154 and 353 on grasses, from 120 to 266 on G. sarothrae, and from 69 to 116 on P. glandulosa. There was a significant relationship between the number of families of insects on grass and G. sarothrae and growing season rainfall but species richness was not a function of growing season rainfall on any of the plants. Several of the arthropod families that were the most species rich in this grassland were found on all of the plants sampled, i.e. Salticid spiders, Bruchid and Curculionid beetles, Cicadellid and Psyllid homopterans, and ants (Formicidae). There were more species rich families that were shared by grasses and the sub-shrub G. sarothrae than with mesquite. The absence of a relationship between growing season rainfall and species richness was attributed to variation in life history characteristics of arthropods and to the non-linear responses of annual and perennial desert grassland plants to rainfall.

There were no significant differences in insect family or species richness on any of the plant types as a result of removal of mesquite (P. glandulosa) from selected plots. Intense, short duration (24\ h) grazing by livestock during in late summer resulted in reduced species richness in the grass-herb vegetation layer but had no effect on insect species richness on snakeweed or mesquite shrubs. Livestock grazing in winter had no effect on insect species richness on any of the vegetation sampled.

}, keywords = {arthropods, canopy, Chihuahuan Desert, desert grassland, livestock grazing, species richness}, doi = {10.1016/j.jaridenv.2004.07.004}, url = {/files/bibliography/05-020.pdf}, author = {Gregory S. Forbes and Justin Van Zee and W. E. Smith and Walter G. Whitford} } @conference {50550, title = {Drought as a Dynamic Process: Recovering from Long Term Rangeland Impacts of Drought}, booktitle = {2005 3rd Annual Drought Summit: "The Drought: It Ain{\textquoteright}t OVer {\textquoteright}Til It{\textquoteright}s Over, and It Ain{\textquoteright}t Over!", USDA Natural Resources Conservation Service}, year = {2005}, month = {October 6, 2005}, pages = {pp. 20}, publisher = {University of New Mexico Continuing Education Center}, organization = {University of New Mexico Continuing Education Center}, address = {Albuquerque, NM}, abstract = {Central tenets of living with drought rangelands are complex, often unpredictable lanscapes, in which drought is a constant feature. The effects of drought are dependent on prior conditions that are largely the result of the continual interplay of humans and their environment. By investing in human capital, and the large social context, we can better manage this interplay to meet a diversity of needs. It is knowledge, and the creation of knowledge, through monitoring and scientific investigation, that allows land management professionals to better adapt and innovate to ever chaning conditions. Likewise, the greater society provides the ethic and the needed flexibility for the land manager to operate within. Without first adressing this often ignored framework, use of other management tools are likely to be costly, have short-lived benefits, and uninteded consequences.}, keywords = {drought management, long term, rangeland}, author = {E.L. Fredrickson} } @article {50564, title = {Determining Research Gaps in Disturbance Data for Fort Bliss and a Conceptual Model}, number = {ERDC/CERL TR-05-038}, year = {2005}, month = {November 2005}, pages = {32}, publisher = {U.S. Corps of Engineers}, address = {Washington, DC}, abstract = {

Numerous research and outside monitoring efforts have been completed for Fort Bliss, Texas. This report summarizes results from previous experiments on military disturbances at this site, and identifies research gaps in disturbance data. These studies (and others) are used to develop conceptual models of the impact of military disturbances on vegetation dynamics in arid lands.

}, keywords = {disturbance data, Fort Bliss, government publication}, url = {/files/bibliography/06-017.pdf}, author = {Hochstrasser, T. and Debra C. Peters and J.S. Fehmi} } @conference {50615, title = {Development of wildlife habitat quality indicators from common vegetation measurements}, booktitle = {Society for Range Management, 58th Annual Meeting and Trade Show}, year = {2005}, month = {February 5, 2005}, pages = {Paper No. 347}, address = {Fort Worth, TX}, abstract = {Wildlife management decisions are often constrained by insufficient information about species-specific wildlife habitat quality. Many vegetation monitoring programs include data on vegetation cover and composition, yet these data are not readily interpreted for wildlife habitat quality assessments because they have not been correlated with more traditional wildlife habitat indicators. The purpose of this study was to evaluate the utility of different vegetation measurements to develop wildlife habitat quality indicators that are correlated with indicators generated from a vegetation cover pole method. Line-point intercept, plant height, gap intercept, and visual obstruction measurements were used to estimate the spatial distribution of above-ground vegetation in grassland, shrubland and woodland communities in New Mexico. Results indicate that visual obstruction measurements constituted a more reliable and more efficiently quantified index of vegetation structure than plant height in shrubland and woodlands, but not in the grassland site. Results showed that indicators generated from standard vegetation measurements are correlated with traditional habitat quality indicators generated from the cover pole. However, the form and strength of these relationships vary among plant communities.}, keywords = {quality indicators, vegetation measurements, wildlife habitat}, author = {David P. Toledo and Jeffrey E. Herrick and Laurie Abbott} } @article {50622, title = {Directional Virtual Fencing (DVF-trademark)}, journal = {Grassroots, Newsletter of the Grassland Society of Southern Africa}, volume = {4}, number = {1}, year = {2004}, month = {February 1, 2004}, pages = {10-13}, abstract = {A novel method is described for controlling free-ranging cows using Global Positioning System (GPS) technology and electromechanical cues delivered through a device termed Directional Virtual Fencing (DVFTM). The device is described as a tool to control animal movement, as well as a device to move groups of animals over the landscape in a manner humane to both instrumented and non-instrumented animals.}, url = {/files/bibliography/03-052.pdf}, author = {D.M. Anderson} } @conference {50623, title = {Directional Virtual Fencing (DVF{\texttrademark})}, booktitle = {57th Annual Meeting of Society for Range Management}, year = {2004}, month = {January 24-30, 2}, pages = {Abstract No. 6}, address = {Salt Lake City, UT}, abstract = {Previous methods for promoting uniform spatial distribution of animals across a landscape have produced mixed results, yet none provide opportunities for real-time management. With Directional Virtual Fencing (DVF)(TM) prescriptive real-time animal management is imminent. The animal-mounted DVF(TM) device combines Global Positioning System (GPS) technology with electro-mechanically produced cues controlled by proprietary algorithms in the device{\textquoteright}s Central Processing Unit (CPU) to control animals in real time. The GPS component in the DVF(TM) device gives animal position on the landscape, while a Geographic Information System (GIS) allows preprogrammed, latitude-longitude pairs to define a Virtual Center Line (VCL)(TM) inside a Virtual Boundary (VB)(TM)). If the VB(TM) is penetrated by an instrumented animal, the direction of its head with respect to the VCL(TM) determines to which side of the animal the independently programmable, left and right side cues will be delivered to elicit the shortest turning direction for movement away from the VCL(TM) with the least cuing stress. Cue intensity is ramped from low at the VB(TM) perimeter to high at the VCL(TM). Should the animal fail to respond appropriately, cuing can be programmed to stop. Cow heart rate is elevated during cuing; however, the increase is only transitory as evidenced by animals quickly returning to graze in the opposite direction following cuing. Preliminary data from a small herd (n = 6) suggests not every animal in a group will need to wear a DVF(TM) device if the goal is to control the group{\textquoteright}s distribution across a landscape.}, keywords = {fencing, Geographic Information System, Global Positioning System, virtual, virtual boundary}, author = {D.M. Anderson and Price, M.A. and E.L. Fredrickson and B. Nolen and C.S. Hale and Kris Havstad} } @proceedings {50643, title = {Differences in grass-shrub transition zone canopy composition from CHRIS/Proba multiangle data}, year = {2004}, month = {September 20, 20}, abstract = {The surface spectral-directional reflectance of a grass-shrub transition zone at 631 nm was estimated from spectral radiance images in a narrow (~10 nm wide) band recorded by the Compact High-Resolution Imaging Spectrometer (CHRIS) flown on the European Space Agency{\textquoteright}s Proba micro-satellite. An experimental satellite-borne sensor developed by Sira Electro-Optics Ltd. (UK), CHRIS is one of the few sources of multi-angular reflectance data on kilometer scales, providing up to five looks in different directions at a given target within the space of a few minutes. For a selected December 23, 2003, overpass, orbital ephemeris were used to obtain the viewing geometry for the set of four available images. The images were resampled to a consistent 25-m grid and used to invert a simple geometric bidirectional reflectance distribution (BRDF) model for plant number density, plant width and plant height. The retrieved parameters were compared to subsets of high-resolution aerial photographs. The inversions did not always result in the expected parameter behavior and further work is required to determine the underlying reasons, which may include decoupling model parameter response to brightness and anisotropy.}, keywords = {canopy composition, CHRIS, grass-shrub transition, multiangle data, PROBA}, url = {/files/bibliography/04-034.pdf}, author = {M. Chopping and Snyder, C. and Andrea S. Laliberte and A. Rango and Connie J. Maxwell} } @article {50650, title = {Deposition and removal of fugitive dust in the arid southwestern United States: Measurements and model results}, journal = {Journal of the Air \& Waste Management Association}, volume = {54}, number = {9}, year = {2004}, note = {//local//NONE//}, month = {2004}, pages = {1099-1111}, abstract = {This work was motivated by the need to better reconcile emission factors for fugitive dust with the amount of geologic material found on ambient filter samples. The deposition of particulate matter with aerodynamic diameter less than or equal to 10 mum (PM10), generated by travel over an unpaved road, over the first 100 m of transport downwind of the road was examined at Ft. Bliss, near El Paso, TX. The field conditions, typical for warm days in the and southwestern United States, represented sparsely vegetated terrain under neutral to unstable atmospheric conditions. Emission fluxes of PM10 dust were obtained from towers downwind of the unpaved road at 7, 50, and 100 m. The horizontal flux measurements at the 7 m and 100 m towers indicated that PM10 deposition to the vegetation and ground was too small to measure. The data indicated, with 95\% confidence, that the loss of PM10 between the source of emission at the unpaved road, represented by the 7 m tower, and a point 100 m downwind was less than 9.5\%. A Gaussian model was used to simulate the plume. Values of the vertical standard deviation sigma(z) and the deposition velocity V, were similar to the U.S. Environmental Protection Agency (EPA) ISC3 model. For the field conditions, the model predicted that removal of PM10 unpaved road dust by deposition over the distance between the point of emission and 100 m downwind would be less than 5\%. However, the model results also indicated that particles larger than 10 mum (aerodynamic diameter) would deposit more appreciably. The model was consistent with changes observed in size distributions between 7 m and 100 m downwind, which were measured with optical particle counters. The Gaussian model predictions were also compared with another study conducted over rough terrain and stable atmospheric conditions. Under such conditions, measured PM10 removal rates over 95 m of downwind transport were reported to be between 86\% and 89\%, whereas the Gaussian model predicted only a 30\% removal. One explanation for the large discrepancy between measurements and model results was the possibility that under the conditions of the study, the dust plume was comparable in vertical extent to,the roughness elements, thereby violating one of the model assumptions. Results of the field study reported here and the previous work over rough terrain bound the extent of particle deposition expected to occur under most unpaved road emission scenarios.}, keywords = {aeolian, boundary-layer, aeolian, emissions, aeolian, PM10 emissions, aeolian, vertical dispersion}, author = {Vicken Etyemezian and Ahonen, S. and Nikolic, D. and J. Gillies and Kuhns, H. and D. E. Gillette and Veranth, J.} } @article {50679, title = {Distribution of plant species at a transition zone between the shortgrass steppe and the Chihuahuan Desert grassland}, journal = {Journal of Vegetation Science}, volume = {15}, number = {4}, year = {2004}, month = {August 1, 2004}, pages = {531-538}, abstract = {The objective of this study was to compare plant species and life form composition of two patch types at a shortgrass steppe, Chihuahuan Desert grassland biome transition zone in central New Mexico, USA. We sought to determine if species were associated with different patch types and if that association was related to differences in soil texture between patch types and the geographic range of subordinate species. Patches dominated by either blue grama, the dominant species in the shortgrass steppe, or black grama, the dominant species in the Chihuahuan Desert grasslands, were sampled at multiple scales for the occurrence of subordinate species and soil texture. Of the 52 subordinate species analyzed, 16 species were associated with blue-grama-dominated patches and 12 species with black-grama-dominated patches. Patches dominated by blue grama were richer in annual grasses and forbs, whereas patches dominated by black grama contained more perennials forbs and shrubs and subshrubs. Soils of blue-grama-dominated patches had higher clay and lower rock contents compared with soils of black-grama-dominated patches. Differences in species characteristics of the dominant species, as well as differences in soil texture between patch types, contribute to patch-scale variation in species and life form composition. Our results show that patch types at this biome transition zone have characteristic life form and species composition, but species are associated to patch types due to local constraints, independently from their affinity to the adjacent biomes.}, url = {/files/bibliography/04-051.pdf}, author = {G. Kroel-Dulay and Odor, P. and Debra C. Peters and Hochstrasser, T.} } @article {50733, title = {Diazotrophic community structure and function in two successional stages of biological soil crusts from the Colorado Plateau and Chihuahuan Desert}, journal = {Applied and Environmental Microbiology}, volume = {70}, number = {2}, year = {2004}, note = {//JER//LTER IV//}, month = {2004}, pages = {973-983}, abstract = {

The objective of this study was to characterize the community structure and activity of N2-fixing microorganisms in mature and poorly developed biological soil crusts from both the Colorado Plateau and Chihuahuan Desert. Nitrogenase activity was approximately 10 and 2.5 times higher in mature crusts than in poorly developed crusts at the Colorado Plateau site and Chihuahuan Desert site, respectively. Analysis of nifH sequences by clone sequ3ncing and the terminal restriction fragment length polymorphism technique indicated that the crust diazotrophic community was 80 to 90\% heterocystous cyanobacteria most closely related to Nostoc spp. and that the composition of N2-fixing species did not vary significantly between the poorly developed and mature crusts at either site. In contrast, the abundance of nifH sequences was approximately 7.5 times greater (per microgram of total DNA) in mature crusts than in poorly developed crusts at a given site as measured by quantitative PCR. 16S rRNA gene clone sequencing and microscopic analysis of the cyanobacterial community within both crust types demonstrated a transition from a Microcoleus vaginatus-dominated, poorly developed crust to mature crusts harboring a greater percentage of Nostoc and Scytonema spp. We hypothesize that ecological factors, such as soil instability and water stress, may constrain the growth of N2-fixing microorganisms at our study sites and that the transition to a mature, nitrogen-producing crust initially requires bioengineering of the surface microenvironment by Microcoleus vaginatus.

}, keywords = {article, articles, bacteria, cyanobacteria, community structure, microorganisms, cryptobiotic crust, journal, journals, nitrogen fixation, soil crusts, soil biota, diazotrophic community}, doi = {10.1128/AEM.70.2.973-983.2004}, url = {files/bibliography/JRN00407.pdf}, author = {Yeager, Chris M. and Kornosky, Jennifer L. and Housman, David C. and Grote, Edmund E. and Jayne Belnap and Kuske, Cheryl R.} } @article {50736, title = {Disposition of rainwater under creosotebush}, journal = {Hydrological Processes}, volume = {17}, year = {2003}, note = {//NMSU//LTER IV//}, month = {2003}, pages = {2555-2566}, abstract = {

In desert shrubland ecosystems water and nutrients re concentrated beneath shrub canopies in {\textquoteright}resource islands{\textquoteright}. Rain falling onto these islands reaches the ground as either stemflow or throughfall and then either infiltrates into the soil or runs off as overland flow. This study investigates the partitioning of rainwater between stemflow and throughfall in the first instance and between infiltration and runoff in the second. Two series of 40 rainfall simulation experiments were performed on 16 creosotebush shrubs in the Jornada Basin, New Mexico. The first series of experiments was designed to measure the surface runoff and was performed with each shrub in its growth position. The second series was designed to measure stemflow reaching the shrub base and was conducted with the shrub suspended above the ground. The experimental data show that once equilibrium is achieved, 16\% of the rainfall intercepted by the canopy or 6.7\% of the rain falling inside the shrub area (i.e., the area inside the shrubs circumscribing ellipse) is funneled to the shrub base as stemflow. This redistribution of the rainfall by stemflow is a function of the ratio of canopy area (i.e., the area covered by the shrub canopy) to collar area (i.e., a circular area centered on the shrub base), with stemflow rate being positively correlated and throughfall rate being negatively correlated with this ration. The surface runoff rate expressed as a proportion of the rate at which rainwater arrives at a point (i.e., stemflow rate plus throughfall rate) is the runoff coefficient. A multiple regression reveals that 75\% of the variance in the runoff coefficient can be explained by three independent variables: the rainfall rate, the ratio of the canopy area to the collar area, and the presence or absence of subcanopy vegetation. Although the last variable is a dummy variable, it accounts for 66.4\% of the variance in the runoff coefficient. This suggests that the density and extent of the subcanopy vegetation is the single most important control of the partitioning of rainwater between runoff and infiltration beneath creosotebush. Although these findings pertain to creosotebush, similar findings might be expected for other desert shrubs that generate significant stemflow and have subcanopy vegetation. Copyright {\textcopyright} 2003 John Wiley \& Sons, Ltd.

}, keywords = {article, articles, creosotebush, hydrology, creosotebush,also SEE , hydrology, creosotebush, hydrology, infiltration, hydrology, overland flow, hydrology, resource islands, hydrology, stemflow, journal, journals, rainfall simulation, hydrology, rainwater, resource islands, hydrology}, doi = {10.1002/hyp.1272}, url = {files/bibliography/JRN00382.pdf}, author = {Athol D. Abrahams and A.J. Parsons and John Wainwright} } @article {50751, title = {Development and use of state-and-transition models for rangelands}, journal = {Journal of Range Management}, volume = {56}, number = {2}, year = {2003}, month = {March 1, 2003}, pages = {114-126}, abstract = {

State-and-transition models have received a great deal of attention since introduction of the to range management concept in 1989. Recently, sets of state-and-transition models have been produced that can be used by agency personnel and private citizens, but there is little guidance available for developing and interpreting models. Thus, we address the following questions: 1) how is information assembled to create site-specific models for entire regions, 2) how are models constructed, 3) what are the challenges to their validity, and 4) how should models be used? We review the general structure of state-and-transition models, emphasizing the distinction between the easily-reversible changes among communities within states and the more persistent, threshold behavior of changes among states (transitions). Both succession and transitions occur, so these models are complementary. Ecological sites serve as a framework for developing and selecting models. We illustrate the importance of clearly delineating ecological sites to produce models and describe how we have dealt with poorly-delineated sites. Producing specific models requires an understanding of ecological mechanisms underlying transitions. Mechanisms tend to fall within discrete categories based upon fundamental ecological processes and their relationships are readily understood. A knowledge of mechanisms is related to the use of ecological indicators to anticipate thresholds. We conclude models should include 1) reference values for quantitative indicators, 2) lists of key indicators and descriptions of changes suggesting an approach to a threshold, and 3) a rigorous documentation of the theory and assumptions (and their alternatives) underlying the structure of each model.

}, url = {/files/bibliography/03-006.pdf}, author = {Brandon T Bestelmeyer and Joel R. Brown and Kris Havstad and Alexander, R. and Chavez, G. and Jeffrey E. Herrick} } @article {50752, title = {Development of badlands and gullies in the Sneeuberg, Great Karoo, South Africa}, journal = {Catena}, volume = {50}, year = {2003}, note = {//South Africa//NONE//}, month = {2003}, pages = {165-184}, author = {Boardman, J. and A.J. Parsons and Holland, R. and Holmes, P. J. and Washington, R.} } @proceedings {50757, title = {Desert landscape scene simulation with simple geometric and radiosity models}, volume = {VI}, year = {2003}, month = {July 21-25, 2003}, pages = {2269-2271}, address = {Toulouse, France}, abstract = {

Previous attempts to model landscape-level, remotely sensed scenes over Chihuahuan Desert grass-shrub transition zones using the simple geometric model (SGM) with measured, large-shrub densities did not result in good matches with multiangular observations from the air. One of the findings of a previous study was that the understory of small shrubs and forbs, such as broom snakeweed (Gutierezzia sarothrae), plays an important role in determining brightness. This has been further explored in modeling studies and shown to be important when using either simple geometric or radiosity modeling techniques. Good matches with observations were found using both techniques when models were driven by field-measured parameters (plant heights, radii, densities, and a background soil BRDF) and explicit plant maps constructed from air photograph and field survey data. The work described here extends modeling to the landscape level (over an area almost 1 km2). This is achieved by estimating understory (small plant) density via a relation with mean image grayscale values masked for large plants in scanned aerial photographs and IKONOS panchromatic imagery. The results indicate that good representations of remotely sensed scenes can be obtained by modeling as long as the soil anisotropy and the understory are taken into account. Future work must address improving estimates of understory density.

}, doi = {10.1109/IGARSS.2003.1294411}, url = {http://ieeexplore.ieee.org/iel5/9010/28604/01294411.pdf?tp=\&arnumber=1294411\&isnumber=28604}, author = {M. Chopping and L. Su and A. Rango and Connie J. Maxwell} } @article {50771, title = {Distribution of Russian knapweed in Colorado: Climate and environmental factors}, journal = {Journal of Range Management}, volume = {56}, number = {6}, year = {2003}, note = {ProCite field[29]: July 29, 2002ProCite field[36]: 2007ProCite field[39]: 03-007}, month = {May 1, 2003}, pages = {206-212}, abstract = {Russian knapweed (Acroptilon repens (L.) DC.) was introduced to the western United States during the early 1900s. This invasive perennial was a contaminant of alfalfa seed and was distributed widely across Colorado. Thus, current distributions reflect the climate and soils tolerances of Russian knapweed and management history rather than dispersal processes. We surveyed extension and weed agents across Colorado and were able to locate 528 current or recently eliminated Russian knapweed stands. These patches were superimposed on climate and soils maps to identify 1-km grid cells that were known to contain Russian knapweed. The status of Russian knapweed within a cell was used as the dependent variable in a logistic regression model to define the environmental envelope for this species. At the scale of our analysis, Russian knapweed was most prevalent on fine-textured soils (clay and clay loam) and in warmer, drier regions of Colorado (precipitation 18-73 cm/yr, mean annual temperature 1-12 C). June precipitation was the most important single factor, although nearly all environmental, annual and monthly climatic factors were significantly related to Russian knapweed occurrence. The multivariate logistic regression model we developed was used to predict the probability of Russian knapweed occurrence for the entire state of Colorado. Our predictions matched the areas of highest abundance of Russian knapweed from a new field survey and also indicated areas of high risk that were not identified by the field survey.}, url = {http://jrm.library.arizona.edu/jrm/GetFileServlet?file=file:///data1/pdf/TheJournalOfRangeManagement/Volume56/Number3/azu_jrm_v56_n3_206_212_m.pdf\&type=application/pdf}, author = {Sarah Goslee and Beck, K.G. and Debra C. Peters} } @article {50788, title = {A digital photographic technique for assessing forage utilization}, journal = {Journal of Range Management}, volume = {56}, number = {2}, year = {2003}, month = {March 1, 2003}, pages = {140-145}, abstract = {Changes in forage utilization have been difficult to measure nondestructively without some level of subjectivity. This subjectivity, combined with a lack of reproducibility of visual estimates, has made forage utilization measurement techniques a topic of considerable discussion. The objective of this study was to develop and test the accuracy and repeatability of an objective, computer-based technique for measuring changes in plant biomass. Digital photographs of target plants acquired before and after partial defoliation were analyzed using readily available image analysis software. Resulting data were used to develop a simple linear random coefficient model (RC) for estimation of plant biomass removed based on the area of the plant in the photo. Sample collection took approximately 20 minutes/plant for alfalfa (Medicago sativa L.). Analysis of images took another 60 to 90 minutes. Regression analysis gave an R2 of 0.969 for predicted vs. observed plant weights. Testing this model using 10 alfalfa plants yielded weight estimates of defoliated plants accurate to within +/- 8.5\%. The advantage of the RC model is its ability to use easily obtained coefficients from simple linear regression models developed from each plant in a way that accounts for the lack of independence between samples within an individual plant. The technique described here offers an objective and accurate method for measuring changes in plant biomass with possible applications in ecology, botany, and range science. In particular, application of this technique for estimating forage utilization may improve accuracy of estimates and, thereby, improve range management practices.}, url = {/files/bibliography/03-015.pdf}, author = {P.W. Hyder and E.L. Fredrickson and M.D. Remmenga and Richard E. Estell and Pieper, Rex D. and D.M. Anderson} } @article {50789, title = {Desertification and biopedturbation in the northern Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {53}, number = {1}, year = {2003}, month = {January 1, 2003}, pages = {1-14}, abstract = {

We examined the relationship between biopedturbation (animal-caused soil disturbance) and several vegetation and soil-based indicators of rangeland condition to evaluate the effects of desertification on animal soil disturbance. The area, volume, and abundance of various biopedturbation types were assessed at 117 sites in south-central New Mexico where vegetative cover and composition had previously been measured. There were significant relationships between biopedturbation and selected rangeland condition indicators. Increasing percentages of grass cover were positively associated with increasing total area of biopedturbation. Increasing percentages of shrub cover and mean bare patch size were negatively associated with total biopedturbation area. Biopedturbation area and volume were related to indicators of rangeland condition and percent shrub cover best predicts the area of soil disturbed by animals. This relationship, however, cannot reliably predict total biopedturbation area or the area of soil disturbance types.

}, keywords = {Biopedturbation, Chihuahuan Desert, condition indicators, desertification, disturbance, rangeland, soil}, doi = {10.1006/jare.2002.1022}, url = {/files/bibliography/03-009.pdf}, author = {E. Jackson and Krogh, S.N. and Walter G. Whitford} } @article {50790, title = {Decomposition of leaf and root litter of Chihuahuan Desert shrubs: Effects of three years of summer drought}, journal = {Journal of Arid Environments}, volume = {53}, number = {1}, year = {2003}, month = {January 1, 2003}, pages = {21-39}, abstract = {

One of the more uncertain aspects of nutrient cycling in desert ecosystems is the extent to which decomposition is controlled by water availability. Some of this uncertainty may be partly related to the duration of the studies and/or differences in the chemical composition of the decaying litter. We conducted a 3-year field study of rainfall to determine the impact of summer (June through September) drought on decomposition of leaf and root litter of two shrub species (Larrea tridentata and Prosopis glandulosa) in the northern Chihuahuan Desert, New Mexico, USA. In both species, leaf litter decayed at a faster rate and was less effected by drought than root litter. Drought had no influence on the rates of decomposition of leaves of either species during the first 18 months but caused decay rates to decline by about 25\% during the latter half of the study. Drought decreased decay of root litter in both species by about 25\% throughout the 3 years. There was a general increase in percent nitrogen (\%N) of decomposing leaf litter in both species. Root litter \%N declined slightly in Larrea but remained relatively constant in Prosopis. Using a modified version of the CENTURY model, we were able to predict most aspects of observed leaf and root litter mass loss and nitrogen dynamics. Overall, the results of this study suggest that relatively large changes in precipitation produce comparatively small changes in rates of decay of both leaf and root litter.

}, keywords = {CENTURY model, Larrea tridentata, Mass loss, nutrient cycling, prosopis glandulosa}, doi = {10.1006/jare.2002.1025}, url = {files/bibliography/JRN00380.pdf}, author = {P. R. Kemp and J. F. Reynolds and R. A. Virginia and Walter G. Whitford} } @proceedings {50813, title = {A developing method for directional virtual fencing (DVF trademark) and real-time range management using remote sensing, GIS and GPS}, year = {2003}, month = {November 10-14, }, pages = {Paper No. TS-11.4}, address = {Honolulu, HI}, abstract = {New technologies have progressed in recent years to the point where capabilities exist to permit development of real-time, rangeland management systems. Various possibilities are available for estimating total forage production using multispectral remote sensing capabilities and spectral indices. Optimum utilization requires herbivores to be moved in a timely manner commensurate with the landscape{\textquoteright}s productivity and facilitated by a Directional Virtual Fencing (DVF) device. DVF combines Global Positioning System (GPS) technology and electromechanically produced directional cues in an innovative approach to control free-ranging animal location and direction of movement in a humane and reproducible manner in real time. A geographically referenced Virtual Boundary (VB) programmed into the unit{\textquoteright}s Geographic Information System (GIS) is combined with the GPS data to determine when a VB is approached and when to move the animal away from the VB. Development, testing, validation, and improvement of the total system is ongoing at the Jornada Experimental Range in southern New Mexico.}, author = {A. Rango and D.M. Anderson and C.S. Hale and Kris Havstad} } @proceedings {50809, title = {Development of a remote-sensing snowmelt runoff forecasting system in the Rio Grande Basin}, year = {2003}, note = {As of 9 July, in press}, month = {04/2003}, address = {Scottsdale, AZ}, abstract = {

Large river basins in arid and semiarid regions such as the Rio Grande need forecasting systems that make use of data obtained from new technologies. For the Rio Grande Basin, we are developing a forecasting system comprised of two linked models designed to use remote sensing data, namely, SRM and SLURP. SLURP requires MODIS satellite data for land use and evapotranspiration determination, and SRM requires MODIS snow-covered area data plus snow water equivalent data from the meteor-burst data relay of SNOTEL. Working on some tributary basins, we have produced streamflow forecasts for 2001-2003. We are in the process of expanding the forecasting to all the snowmelt sub-basins, as well as basins where rainfall dominates. The final product should assist local, state, and federal agencies in making improved water management decisions in the complex and water-limited Rio Grande Basin.

}, url = {files/bibliography/Rango2003-01.pdf}, author = {A. Rango and E. Gomez-Landesa and Kris Havstad and M. Bleiweiss and Tanksley, K. and D. DeWalle and J. Martinec and G. Kite} } @article {50829, title = {Defoliation alters water uptake by deep and shallow roots of Prosopis velutina (velvet mesquite)}, journal = {Functional Ecology}, volume = {17}, number = {3}, year = {2003}, month = {June 1, 2003}, pages = {363-374}, abstract = {1. Prosopis velutina Woot. (Velvet Mesquite) at a site with limited groundwater availability derived a greater percentage of water from shallow soil at the onset of the summer rainy season than did trees at a site with greater availability of groundwater. Predawn leaf water potentials were not a strong indicator of shallow water use for this species with roots in multiple soil layers.2. We experimentally defoliated P. velutina plants to determine if reduced-canopy photosynthesis would alter vertical patterns of root activity. After natural rain events, hydrogen isotope ratios of xylem sap indicated that defoliated P. velutina took up a greater percentage of its water from shallow soils than did undefoliated plants.3. Irrigation with deuterium-labelled water further demonstrated that undefoliated plants were able to use shallow soil water. Defoliation appeared to affect the ability of trees to use deep-water sources.4. Reduced carbon assimilation limited water uptake from deep soil layers. These data highlight that there are internal physiological controls on carbon allocation that may limit water uptake from different soil layers. During periods of high vapour pressure deficit or soil drought, when leaf gas exchange and carbon assimilation decline, this may create positive feedbacks where plants are unable to forage for deep water due to carbon limitations.}, url = {/files/bibliography/03-034.pdf}, author = {K. A. Snyder and Williams, D.G.} } @article {50860, title = {Do morphological changes mediate plant responses to water stress? A steady-state experiment with two C4 grasses}, journal = {New Phytologist}, volume = {155}, number = {1}, year = {2002}, note = {//USDA//LTER IV//entered 6/27/2002; updated 4/7/2009; pdf available}, month = {2002}, pages = {79-88}, abstract = {It was hypothesized that plant growth reduction under water stress is caused primarily by a reduction of leaf-area ration (LAR, leaf area per unit of total plant dry mass). Two perennial Chihuahuan desert grass species (slow-growing Bouteloua eriopoda and fast-growing Eragrostis lehmanniana) were subjected over 6 weeks to a combination of two water-supply regimes (control and drought) and two levels of atmospheric CO2 partial pressure (375 and 750 {\`\i}mol mol-1). Drought reduced final biomass in Bouteloua by 60\% regardless of CO2 concentration. Eragrostis experienced a similar biomass reduction at 375 {\`\i}mol mol-1, but large plants under elevated CO2 attained growth rates comparable to those of controls. Overall, for plants of similar size, drought reduced LAR in both species much more strongly than it affected net assimilation rate. This reduction in LAR was caused by reductions in both specific leaf area and leaf weight ratio. We conclude that reduced growth under drought can be considered as a byproduct of the same plastic, developmental responses that result in a reduced water loss.}, keywords = {article, articles, Bouteloua eriopoda, Bouteloua, drought, Bouteloua, growth analysis, Bouteloua, plasticity, Bouteloua, water use efficiency (WUE), drought tolerance, grass, drought, Bouteloua, drought, Eragrostis, Eragrostis lehmanniana, Eragrostis, drought, Eragrostis, growth analysis, Eragrostis, plasticity, Eragrostis, water use efficiency (WUE), journal, journals, plant, Bouteloua, plant, Eragrostis, water-use efficience, Bouteloua, water-use efficiency, Eragrostis}, url = {http://www.newphytologist.com}, author = {Roberto J. Fern{\'a}ndez and Wang, Mengben and J. F. Reynolds} } @proceedings {50865, title = {Desertification: Weaving together the complexities of time and place}, year = {2002}, month = {September 17-20,}, pages = {18-26}, address = {Durango, Mexico}, abstract = {Desertification is an active process in the Chihuahuan Desert that is typified by a vegetation transition from desert grasslands to desert scrub. Throughout much of geological time, deserts have waxed and waned without human intervention. Currently, it is difficult to segregate human and nonhuman causes. One obvious cause of this transition is a dynamic interaction between plant species with and without specific adaptations to large animal herbivory. An examination of vegetation change with time reveals that deserts are complex, chaotic, and often catastrophic. New models are being developed to deal with the resulting uncertainty. These models include complex adaptive systems and adaptive management. These models are discussed and applied to conditions prevalent in the Chihuahuan Desert.}, url = {/files/bibliography/02-023.pdf}, author = {E.L. Fredrickson and Amy L. Gonzalez} } @conference {50875, title = {Dietary preferences of black-tailed prairie dogs (Cynomys ludovicianus) reintroduced into a Chihuahuan Desert grassland}, booktitle = {55th Annual Meeting, Society for Range Management}, year = {2002}, month = {February 13, 200}, pages = {67}, address = {Kansas City, MO}, abstract = {During the first half of the last century, black-tailed prairie dogs (Cynomys ludovicianus) were exterminated from most of their range in the Chihuahuan Desert. Their removal coincides with the transition of desert grasslands to desert scrub conditions. The role of prairie dog extermination in facilitating this transition is currently unknown. In addition, prairie dogs were recently considered for listing as a threatened species. Subsequent rulings from this action have resulted in greater need for methods to manage prairie dog populations. To better understand how prairie dogs affect Chihuahuan Desert vegetation dynamics and to improve the success of reintroduction efforts, a study was undertaken to assess the dietary preferences of black-tailed prairie dogs reintroduced into a Chihuahuan Desesrt grassland. Three colonies were established in an alkali sacaton (Sporobulus airoides)/tobosa (Pleuraphis mutica)/burrograss (Scleropogon brevifolius) grassland with deep, well drained, silt-loam soils. Ten active burrows were randomly selected within each colony and vegetative cover composition and species biomass were estimated using 20-m transects. Feces were obtained from the entrance of each burrow for microhistological analysis. Preliminary results for four seasons suggest grasses are preferred to forbs with vine mesquite (Panicum obtusum) being highly preferred.}, author = {Hartsough, M.J. and E.L. Fredrickson and J. Truett and Reldon F. Beck} } @article {50881, title = {A dynamic cone penetrometer for measuring soil penetration resistance}, journal = {Soil Science Society of America Journal}, volume = {66}, number = {4}, year = {2002}, month = {July 1, 2002}, pages = {1320-1324}, abstract = {

Recognition of the importance of soil compaction is increasing, but instrument cost, measurement repeatability and data interpretation limit its measurement on agricultural and rangelands. The dynamic penetrometer described here follows ASAE standards but replaces the proving ring with a strike plate, a shaft extension and a sliding hammer. The penetrometer cone eis pushed into the soil by successive hammer blows. Penetration resistance is calculated as the work by the soil needed to stop cone movement divided by the penetration distance. The work by the soil is defined as the kinetic energy of the hammer when it impacts the strike plate. Construction cost is approximately US$100. The standard drop height and hammer mass ensure measurements are consistent between operators.

}, keywords = {agricultural, American Society of Agricutlural Engineers standards, cone movement, dynamic penetrometer, ensure measurements, hammer mass, impacts, kinetic energy, penetration distance, Penetration resistance, proving ring, rangelands, shaft extension, sliding hammer, soil, soil compaction, standard drop height, strike plate}, doi = {10.2136/sssaj2002.1320}, url = {/files/bibliography/02-034.pdf}, author = {Jeffrey E. Herrick and Jones, T.L.} } @conference {50889, title = {Disturbance, vegetation and climate: determining critical factors affecting recovery in desert grasslands}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {159}, address = {Tucson, AZ}, abstract = {In arid ecosystems, disturbances such as fire and grazing are attributed both to ecosystem degradation and to restoration. The objective of this study was to determine the disturbance and climatic conditions that maintain current vegetation and the conditions that result in a shift to different vegetation types. Because life history and physiological characteristics of plants can filter the impact of disturbances, vegetation change may also depend on the current vegetation type. We used an individual-based simulation model (ECOTONE) to investigate how differences in characteristics of grasses and shrubs determine their responses to disturbances under different climate scenarios in the desert grasslands of southern New Mexico. The simulated disturbance types included those that remove aboveground biomass from the entire plant community, those that only remove the biomass from certain species, and those that only affect soil characteristics. Climatic conditions during recovery from disturbance were simulated to include short-term and long-term droughts and wet periods. We found the timing of the disturbance with respect to climatic events played an important role in determining the lifeform that recovered more quickly. Drought impacted grass recovery more than shrub recovery. Dispersal and establishment characteristics were the most important traits for grass recovery, whereas the most important characteristic for shrubs was biomass allocation pattern. Our results revealed complex interactions among vegetation, disturbance, and climate and all three appear important for maintenance and restoration of grasslands in arid regions.}, author = {Hochstrasser, T. and Debra C. Peters and J.S. Fehmi} } @conference {50892, title = {Dynamic soil properties and advancing the science of soil change}, booktitle = {Annual Meeting, American Society of Agronomy-Crop Science Society of America-Soil Science Society of America}, volume = {CD-ROM}, year = {2002}, month = {November 10-14, }, pages = {Abstract No. S05-tugel1102030-Oral}, address = {Indianapolis, IN}, abstract = {To make a consistent inventory of the soil resource, soil classification, mapping and interpretation are supported by pedological concepts based on soil properties that change relatively little. Concepts of soil change in soil survey are based primarily on the pedogenic time scale of thousands of years. However, management, disturbances and land use can change soil properties over periods of hundreds of years or less. There is increasing demand for information about management time-scale changes in resource condition, ecological processes, and the capacity of soil to function (e.g., support productivity and biodiversity, partition water, cycle nutrients, and filter and buffer contaminants). Pedological concepts for soil change need to include dynamic soil properties and their role in ecological processes, soil resistance and resilience. Information on dynamic and relatively static soil properties needs to be integrated to describe and predict the effects of management on soil functions, to develop soil interpretations, and to predict the sustainability of the soil resource. Pedologists, biologists and ecologists working together can advance the science of soil change.}, author = {D. B. Hudson and A.J. Tugel and Puckett, W. and Norfleet, M.L.} } @article {50893, title = {Desertification alters patterns of aboveground net primary production in Chihuahuan ecosystems}, journal = {Global Change Biology}, volume = {8}, year = {2002}, note = {//NMSU,USDA//LTER IV//}, month = {2002}, pages = {247-264}, abstract = {

The Chihuahuan desert of New Mexico has changed in historical times from semiarid grassland to desert shrublands dominated by Larrea tridentata and Prosopis glandulosa. Similar displacement of perennial grasslands by shrubs typifies desertification in many regions. Such structural vegetation change could alter average values of net primary productivity, as well as spatial and temporal patterns of production. We investigated patterns of aboveground plant biomass and net primary production in five ecosystem types of the Jornada Basin Long-Term Ecological Research (LTER) site. Comparisons of shrub-dominated desertified systems and remnant grass-dominated systems allowed us to test the prediction that shrublands are more heterogeneous spatially, but less variable over time, than grasslands.We measured aboveground plant biomass and aboveground net primary productivity (ANPP) by species, three times per year for 10 years, in 15 sites of five ecosystem types (three each in Larrea shrubland, Bouteloua eriopoda grassland, Prosopis dune systems, Flourensia cernua alluvial flats, and grass-dominated dry lakes or playas). Spatial heterogeneity of biomass at the scale of our measurements was significantly greater in shrub-dominated systems than in grass-dominated vegetation. ANPP was homogeneous across space in grass-dominated systems, and in most growing seasons was significantly more patchy in shrub vegetation. Substantial interannual variability in ANPP complicates comparison of mean values cross ecosystem types, but grasslands tended to support higher ANPP values than did shrub-dominated systems. There were significant interactions between ecosystem type and season.Grasslands demonstrated higher interannual variation than did shrub systems. Desertification has apparently altered the seasonality of productivity in these systems; grasslands were dominated by summer growth, while sites dominated by Larrea or Prosopis tended to have higher spring ANPP. Production was frequently uncorrelated across sites of an ecosystem type, suggesting that factors other than season, regional climate, or dominant vegetation may be significant determinants of actual NPP.

}, keywords = {article, articles, climate change, community dynamics, climate, Chihuahuan Desert, climate, desertification, climate, grassland, desertification, journal, journals, Larrea tridentata, net primary production, plant community, change, plant community, creosotebush, plant community, diversity, plant community, mesquite, plant community, productivity, plant community, tarbush, plant community, vegetation sampling, plant, environmental change, plant, Flourensia, plant, Larrea tridentata, plant, primary production, plant, productivity, plant, Prosopis, plants, net primary production, playa, productivity, playa, vegetation patterns, prosopis glandulosa}, doi = {10.1046/j.1365-2486.2002.00473.x}, url = {files/bibliography/JRN00354.pdf}, author = {L. Huenneke and John P. Anderson and M.D. Remmenga and W. H. Schlesinger} } @article {50895, title = {Distribution and concentration of total phenolics, condensed tannins, and nordihydroguaiaretic acid (NDGA) in creosotebush (Larrea tridentata)}, journal = {Biochemical Systematics and Ecology}, volume = {30}, number = {10}, year = {2002}, month = {November 1, 2002}, pages = {905-912}, abstract = {Shrubs have been replacing arid grasslands over large parts of the American southwest for most of the last century. Multiple mechanisms have been proposed to explain this vegetation shift. One hypothesis invokes allelopathy as a mechanism for maintenance of shrub dominance in former arid grasslands. This paper focuses on the presence and distribution of compounds with allelopathic and/or phytotoxic potential found within creosotebush [Larrea tridentata (Sess. \& Moc. ex DC.) Cov. Total phenolics, condensed tannins and nordihydroguaiaretic acid (NDGA) were measured in nine categories of tissue within creosotebush. Total phenolic and condensed tannin concentrations were determined using colorimetric methods while NDGA content was determined with high performance liquid chromatography (HPLC). Total phenolics were present throughout the plant with highest concentrations in leaves (36.2 mg/g), green stems (40.8 mg/g) and roots (mean for all root categories = 28.6 mg/g). Condensed tannins were found in all tissues except larger woody stems (5 to 12mm in diameter) with highest concentrations in flowers (1.7 mg/g), seeds (1.1 mg/g), and roots less than 5mm in diameter (1.1 mg/g). Flowers, leaves, green stems and small woody stems (<5mm in diameter) all contained NDGA with highest concentrations in leaves (38.3 mg/g) and green stems (32.5 mg/g). The distribution and nature of secondary compounds are variable among various locations within the plant. Moreover, secondary compounds are present in locations and concentrations that suggest they could have a role in allelopathic and/or phytotoxic interactions with surrounding organisms.}, url = {/files/bibliography/02-044.pdf}, author = {P.W. Hyder and E.L. Fredrickson and Richard E. Estell and M.R. Tellez and Gibbens, Robert P.} } @conference {50897, title = {Desertification and biopedturbation in the Chihuahuan Desert}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {369}, address = {Tucson, AZ}, abstract = {We examined the relationship between biopedturbation (animal-caused soil disturbance) and several vegetation- and soil-based indicators of rangeland health to evaluate the effects of desertification on animal soil disturbance. The area, volume and abundance of various disturbance types were assessed at 117 sites in south-central New Mexico where vegetative cover and composition had been previously measured. There were significant relationships between biopedturbation and selected rangeland health indicators. Increasing percentage of shrub cover and bare patch size were both negatively associated with total soil disturbance area. Shrub cover best predicted the area of soild disturbed by animals. This relationship, however, cannot reliably predict total biopedturbation area or the area of soil disturbance types.}, author = {E. Jackson and Walter G. Whitford} } @conference {50898, title = {Does kangaroo rat graminivory contribute to the persistence of desertified shrublands?}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {177}, address = {Tucson, AZ}, abstract = {Medium-sized kangaroo rats (Dipodomys merriani and D. Ordi) have been shown to be keystone species in the dynamics of desert bunchgrasses, and the mechanism has been suggested to be through direct graminivory of the grasses. We tested the hypotheses that kangaroo rats preferentially consumed grasses from small tussocks or tussocks that were surrounded by open habitat by observing the extent and effects on growth and inflorescence production of graminivory in grasses from which kangaroo rats were excluded, as well as on grasses varying in tussock size or the extent of surrounding cover. Our data support the above hypotheses with grasses protected from kangaroo rat graminivory showing significantly elevated leaf growth, tiller growth and inflorescence production. Grass tillers subject to kangaroo rat graminivory did not recover and produce inflorescences when protected from kangaroo rats. Furthermore, grass tussocks that were protected by surrounding vegetation or large grass tussocks suffered significantly lower graminivory than tussocks in the open or small tussocks, respectively. We used these observations to develop a conceptual model whereby kangaroo rats may contribute to the persistence of desertified shrublands.}, author = {G. I. H. Kerley and Walter G. Whitford} } @article {50920, title = {Desert dogma revisited: coupling of stomatal conductance and photosynthesis in the desert shrub, Larrea tridentata}, journal = {Plant, Cell and Environment}, volume = {25}, year = {2002}, note = {//NMSU//LTER IV//}, month = {2002}, pages = {909-921}, abstract = {The success of the desert shrub Larrea tridentata (creosotebush) has been largely attributed to temperature acclimation and stomatal control of photosynthesis (A) under drought stress. However, there is a paucity of field data on these relationships. To address this void, we conducted a joint field and modeling study that encompassed a diverse set of environmental conditions. At a Larrea-dominated site in southern New Mexico we manipulated soil moisture during the growing season over a 2-year period and measured plant pre-dawn water potential ({\O}pd), stomatal conductance (g) and A of individual shrubs. We used these data to develop a semi-mechanistic photosynthesis model (A-Season) that explicitly couples internal CO2 (Ci) and g. Vapor pressure deficit (VPD) and {\O}pd affect instantaneous g in a manner that is consistent with a biophysical model of stomatal regulation of leaf water potential. Ci is modeled as a function of g, derived from a simplification of a typical A-Ci curve. After incorporating the effects of growing temperature on stomatal behavior, the model was able to capture the large diurnal fluctuations in A, g and Ci and the observed hysteresis in g versus Ci dynamics. Our field data and application of the A-Season model suggest that dogma attributed to Larrea{\textquoteright}s success is supported with regard to stomatal responses to VPD and {\O}pd but not for mechanisms of temperature acclimation and CO2 demand.}, keywords = {article, articles, journal, journals, Larrea, evapotranspiration, Larrea, photosynthesis, Larrea, transpiration, Larrea,gas-exchange, model, A-Season, model, Ball-Berry, model, Larrea, model, Leuning, model, Pitman, photosynthesis, Larrea, physiology, Larrea}, author = {Ogle, K. and J. F. Reynolds} } @mastersthesis {50921, title = {The development of an in vitro system to determine the role of endophytic fungus (Aspergillus ustus) on Daucus carota roots}, year = {2002}, note = {//NONE//LTER IV//ProCite field[12]: Not in File (11/08/2005)}, month = {2002}, pages = {134}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {dissertation, fungi, Aspergillus, fungi, endophytic, thesis}, author = {P. Osuna-Avila} } @inbook {50937, title = {Desertification}, booktitle = {Encyclopedia of Global Change}, year = {2002}, note = {//??//LTER III//ProCite field[6]: In}, month = {2002}, pages = {253-256}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {book, books, chapter, chapters, desertification, report, reports}, author = {W. H. Schlesinger}, editor = {A.S. Goudie and Cuff, D. J. (eds.)} } @conference {50972, title = {Developing and applying state-and-transition models to manage rangelands}, booktitle = {86th Annual Meeting, Ecological Society of America}, year = {2001}, month = {August 5-10, 200}, pages = {7}, address = {Madison, WI}, abstract = {State-and-transition models represent theories about the causes of threshold changes between ecosystem types in response to temporal changes in land use and/or climate. In contrast to the quantitative climax model that views ecosystem change as gradual and reversible, the state-and-transition concept holds that disturbances catalyze a shift in positive feedbacks between plants and ecosystem properties, such as nutrient availability and erosion potential, that may lead to irreversible changes in plant and animal composition. Applying this concept to rangeland management will require attention to the processes underlying threshold changes in varying contexts. We propose a set of standard definitions and a format for displaying individual state-and-transition models. We discuss how various sources of information on the processes underlying plant community pattern and dynamics can be brought together to develop predictive state-and-transition models. We argue the utility of models depends critically upon 1) the identification of appropriate spatial and temporal scales for measurement and management, 2) the identification of appropriate windows of climatic, topographic, and soil conditions within which systems behave similarly and that serve as a basis for model classification, 3) the recognition of system openness to landscape influences, and 4) acknowledgment of the case-contingent operation of different mechanisms. We illustrate how insights from community and landscape ecology can be blended with the historical perspective and practical experiences of land managers to build models.}, author = {Brandon T Bestelmeyer and T.K. Stringham and Joel R. Brown and Kris Havstad} } @proceedings {50998, title = {Development and transfer of monitoring and assessment technologies for North American rangelands}, year = {2001}, month = {November 6-7, 20}, pages = {1-4}, address = {Weslaco, TX}, abstract = {The USDA/ARS action plan for the National Program in Rangeland, Pasture, and Forages contains five research components. The first component of this action plan, developed in 1999-2000, is entitled "Ecosystems and their Sustainable Management." One of the main problem areas within this research component is "Monitoring and Assessment Technologies" with the following three goals: (1) Develop and calibrate monitoring systems that reflect basic ecosystem functions and are rapid, quantitative, repeatable, and applicable at a variety of spatial scales. Systems should be designed to function in diverse ecosystems, integrate new tools as they become available, and permit users to select from a range of indicators depending on their objectives, the particular ecosystem, and available resources. (2) Develop new tools to monitor and assess rangelands and pastures at large scales and others to scale up data collected at individual points in the landscape and to interpret data in the context of processes occurring across large areas. (3) Develop additional tools that more precisely reflect specific ecosystem functions and that can be used to distinguish fluctuations in ecosystem processes from directional trends in these processes.}, keywords = {assessment, monitoring, North American rangelands, sustainable management, technologies}, author = {Kris Havstad} } @conference {51004, title = {Disturbance effects on infiltration and erosion susceptibility for biologically crusted soils in the Mojave Desert}, booktitle = {86th Annual Meeting, Ecological Society of America}, year = {2001}, month = {August 5-10, 200}, pages = {291}, address = {Madison, WI}, abstract = {The effects of soil surface disturbance on water infiltration into arid and semi-arid soils have been widely debated in both the popular and scientific literature. Previous studies suggest biological crusting reduces infiltration on soils with >80\% sand content. We tested the hypothesis that trampling would significantly increase infiltration and sediment production at sandy Mojave Desert sites dominated by biological crusts. W used a rainfall simulator to apply an intense 30-minute storm to four trampled and nontrampled plots at each of three sites with physical crusts and three sites with biological crusts, as indicated by soil chlorophyll analyses. Differences in crust cover were attributed to historic disturbance regime. Trampling reduced the infiltration rate 36\% at both the physically and biologically crusted sites. Trampling increased sediment production by a factor of 2.4 at the sites dominated by physical crusts and by a factor of 4.1 at the biologically crusted sites. Chlorophyll content was negatively correlated with sediment production and positively correlated with soil aggregate stability. We concluded maintenance of biological crusts should reduce soil erosion. The hypothesis that biological crusts reduce infiltration capacity on sandy soils was not supported by the data.}, author = {Jeffrey E. Herrick and Jayne Belnap and Justin Van Zee and J. Johansen} } @inbook {51009, title = {Deserts}, booktitle = {Global Biodiversity in a Changing Environment: Scenarios for the 21st Century}, year = {2001}, note = {//?//LTER IV// Updated 12/17/2005ProCite field[6]: In}, month = {2001}, pages = {201-222}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {New York, NY}, keywords = {book, books, chapter, chapters, desert, report, reports}, author = {L. Huenneke}, editor = {O. E. Sala and F.S. Chapin III and E. Huber-Sannwald} } @article {51015, title = {Detecting fragmentation of cover in desert grasslands using line intercept}, journal = {Journal of Range Management}, volume = {54}, number = {1}, year = {2001}, month = {January 1, 2001}, pages = {61-66}, abstract = {We examined the relationship between a Chihuahuan Desert grassland keystone species (banner-tailed kangaroo rat, Dipodomys spectabilis) and several vegetation and soil indicators of rangeland health in order to define a threshold indicator value for irreversible change in ecosystem structure and function. The abundance of occupied and/or abandoned D. spectabilis burrow-mounds was assessed at 117 sites in south central New Mexico where previous studies had reported vegetation cover and composition. The most robust indicator for presence/absence of D. spectabilis was shrub cover. D. spectabilis did not occur at sites with shrub cover greater than 20\%. It was concluded that a threshold value of 20\% shrub cover could be applied to assessment and monitoring of Chihuahuan Desert rangelands because higher shrub cover results in the local extinction of this keystone species. The combination of data on the presence/absence of a keystone species with vegetation and soil indicators provides a method for identifying thresholds of degradation that may be irreversible.}, keywords = {Chihuahuan Desert, grassland, indicators, keystone species, rangeland health, shrub cover}, url = {http://jrm.library.arizona.edu/jrm/GetFileServlet?file=file:///data1/pdf/TheJournalOfRangeManagement/Volume54/Number1/azu_jrm_v54_n1_61_66_m.pdf\&type=application/pdf}, author = {Kuehl, R.O. and M.P. McClaran and Justin Van Zee} } @article {51027, title = {Degradation of sandy arid shrubland environments: observations, process modelling, and management implications}, journal = {Journal of Arid Environments}, volume = {47}, year = {2001}, note = {//USDA//LTER IV// In file and Updated 12/15/2005}, month = {2001}, pages = {123-144}, abstract = {

Field remote sensing, and modelling observations from a degraded Mojave Desert shrubland were used to develop a model of the progressive degradation of areas adjacent to sites of direct anthropogenic disturbance. Aeolian removal and transport and dust, sand, and litter are the primary mechanisms of degradation, killing plants by burial and abrasion, interrupting natural processes of nutrient accumulation, and allowing the loss of soil resources by abiotic transport. It is concluded that any arid shrubland with wind-erodible soils is susceptible to degradation, and where possible development of these lands should be avoided.

}, keywords = {agriculture, article, articles, desertification, journal, journals, landscape, ecosystem dynamics, management, shrublands, model, process, Mojave Desert, paleolakes, shrubland, degradation, shrublands, wind erosion}, doi = {10.1006/jare.2000.0711}, url = {files/bibliography/JRN00324.pdf}, author = {Gregory S. Okin and Murray Bruce and W. H. Schlesinger} } @inbook {51026, title = {Desertification in an arid shrubland in the southwestern United States}, booktitle = {Land Degradation}, year = {2001}, note = {//NMSU,USDA//LTER IV//ProCite field[6]: In}, month = {2001}, pages = {53-70}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, address = {Dordrecht}, abstract = {

In the Mojave Desert of the southwestern U.S. human destruction of soil crusts and removal of vegetation have led to progressive, expanding degradation of adjacent arid shrublands. Aeolian mobilisation of dust, sand and litter triggered by anthropogenic disturbance contributes to the destruction of islands of fertility in adjacent areas by killing shrubs through burial and abrasion. This interrupts nutrient-accumulation processes and allows the loss of soil resources by abiotic transport. Thus the processes of degradation spread across the landscape driven largely by abiotic processes.

Soil chemical analyses and remote sensing observations presented here are designed to test a model hypothesis of degradation of arid shrublands. Nutrient and non-nutrient chemical species in the soil act as tracers of material transport and provide clues as to the nature of progressive anthropogenic degradation in arid shrublands. Remote sensing yields information about short- and long-term effects on the landscape as well as important constraints on the magnitude of degradation. Field, chemical and remote sensing observations argue for an extension of recent definitions and models of desertification to include the loss of islands of fertility in established shrublands. This extended model places arid shrublands in a continuum of physical and ecological processes and ecosystems that links semiarid grasslands with Sahara-like hyperarid barren lands.

}, keywords = {book, books, chapter, chapters, desertification, shrubland, Model Hypothesis, Mojave Desert, report, reports, Semiarid Grassland, shrubland, desertification, soil crust, wind erosion}, doi = {10.1007/978-94-017-2033-5_4}, url = {files/bibliography/JRN00325.pdf}, author = {Gregory S. Okin and Murray, B. and W. H. Schlesinger}, editor = {Conacher, A. J. ed.} } @article {51025, title = {Distribution of vegetation in wind-dominated landscapes: implications for wind erosion modeling and landscape processes}, journal = {Journal of Geophysical Research}, volume = {106}, year = {2001}, note = {//USDA//LTER IV//}, month = {2001}, pages = {9673-9684}, abstract = {

Dust emission and wind erosion from arid and semiarid environments provide a major source of global atmospheric aerosols. Well-known relations between wind stress and saltation sand flux for sand sheets and relations between sand flux and dust emission by sandblasting have enabled construction of dust models that have only been partly successful in predicting atmospheric mineral dust concentrations. Most models of wind erosion assume that vegetation is evenly distributed. Through the use of field, Fourier transform, and semivariogram analysis, we show that mesquite dunelands in the Chihuahuan Desert of southern New Mexico, United States, have anisotropic shrub distributions. Elongated areas of bare soil, {\textquotedblleft}streets,{\textquotedblright} which are aligned with the prevailing winds may partially explain discrepancies between observed and predicted atmospheric dust concentrations. Soils in the streets are not protected from winds blowing down the streets and may therefore produce more dust than if vegetation were more evenly distributed. Currently, few desert landscape evolution models take the role of wind explicitly into account. The existence of streets implies that wind plays a major role in the evolution of vegetated arid and semiarid landscapes with wind-erodible soils. Here wind acts in tandem with water to enforce islands of fertility centered around individual shrubs and may provide an explanation for reduced soil fertility observed in shrublands. Furthermore, in order for mathematical models of dust flux to be successful in these landscapes, new landscape models are required which incorporate the existence and orientation of streets.

}, keywords = {aeolian processes, vegetation effects, aeolian processes, wind erosion, article, articles, journal, journals, model, wind erosion, wind erosion, }, doi = {10.1007/978-94-017-2033-5_4}, url = {files/bibliography/JRN00327.pdf}, author = {Gregory S. Okin and D. E. Gillette} } @inbook {51035, title = {Desertification}, booktitle = {Encyclopedia of Biodiversity, Volume 2}, year = {2001}, note = {//NONE//NONE//ProCite field[6]: InProCite field[8]: Editor-in-ChiefProCite field[36]: In}, month = {2001}, pages = {61-78}, publisher = {Academic Press}, organization = {Academic Press}, address = {San Diego, CA}, abstract = {The phenomenon of desertification involves the loss of biological or economic productivity and biodiversity in arid and semiarid croplands, pastures, rangelands, and subhumid woodlands due mainly to nonsustainable human activities, such as overcultivation, fuel gathering, overgrazing by domestic animals, deforestation, and poor irrigation practices, and is often triggered or exacerbated by climate variability, mainly drought.}, keywords = {book, books, chapter, chapters, desertification, model, desertification, report, reports}, author = {J. F. Reynolds}, editor = {Simon Asher (ed. Levin} } @article {JRN54298, title = {Dispersion of kangaroo rat mounds at multiple scales in New Mexico, USA}, journal = {Landscape Ecology}, volume = {6}, year = {2001}, pages = {267-277}, author = {Robert L. Schooley and J.A. Wiens} } @inbook {51045, title = {The Dynamics of Soil Carbon in Rangelands}, booktitle = {Carbon Sequestration Potential of U.S. Grazing Lands}, year = {2001}, note = {ARIS entry by Rangeland Resources Research, Cheyenne, WY}, month = {2001}, pages = {267-290}, publisher = {Ann Arbor Press}, organization = {Ann Arbor Press}, chapter = {11}, address = {Chelsea, MI}, abstract = {Carbon dynamics of rangeland soils are very complex and only limited detailed research has been conducted to assess the role of management and grazing strategies on soil C changes and the potential for enhanced C sequestration. Soil erosion also can impact the soil C pools in rangeland ecosystems, but much of the erosion does not result in loss of C from the landscape but rather a repositioning on the landscape. In an attempt to estimate the effects of management on the C storage potential of the rangeland ecosystems, we have reviewed the literature on the subject and made some assumptions in order to make some qualitative estimates of C sequestration potential and potential avoided losses of C through management. We believe about 19 Tg C yr-1 can be sequestered through management on lands that are in need of improved management and through soil C regeneration in CRP lands. However, we estimate that 44 Tg C yr-1 can be maintained through ensured good management and by preventing CRP lands from being brought back into crop production. The estimated 63 Tg C yr-1 that can be sequestered and/or prevented from being lost from well- managed rangelands and through maintenance of CRP lands may be small in comparison to the estimates of C sequestration by improved production prac- tices on croplands in the U.S.; however, this level of C storage in a natural ecosystem tends to be more stable and less prone to major C losses through erosional losses and shifts in management.}, keywords = {C storage, grazing strategies, management, rangeland, sequestration, soil carbon}, url = {/files/bibliography/01-073.pdf}, author = {G.E. Schuman and Jeffrey E. Herrick and Janzen, H.H.} } @article {51096, title = {Demographic variation in a desert shrub, Larrea tridentata, in response to a thinning treatment}, journal = {Journal of Arid Environments}, volume = {45}, year = {2000}, note = {//USDA//LTER III//}, month = {2000}, pages = {315-323}, abstract = {We performed a perturbation experiment to determine the relative importance of intra-specific competition on the demographic performance of a population of creosotebush, Larrea tridentata. From 1992 to 1995, we following 1000 individuals, half of which were in plots subjected to a thinning treatment, and the other half were in unmanipulated plots. We found no significant response to the thinning treatment for any of the traits studied. The strict interpretation of these results is that intra-specific competition is not important in this Larrea population.}, keywords = {article, articles, competition, creosotebush, journal, journals, Larrea, competition, Larrea, density-dependence, Larrea, population regulation, population dynamics, Larrea}, author = {Richard E. Miller and L. Huenneke} } @conference {51109, title = {Development of techniques for the elucidation of plant-based diets of free-ranging herbivores using fluorescence spectroscopy}, booktitle = {Annual Meeting, Federation of Analytical Chemistry and Spectroscopy Societies}, year = {2000}, month = {2000}, pages = {p. 267}, abstract = {The determination of the dietary intake of domestic livestock is necessary for their effective management. This becomes more difficult when the animals are allowed to feed on native flora in open rangeland. Efforts in the past to provide information regarding a particular animal{\textquoteright}s dietary habits have used either highly invasive techniques or methods that are time eand labor intensive and very subjective. The development instrumentation to enable the interrogation of samples using multi-dimensional fluorescence measurements for rapid, objective identification of those plants eaten by a specific animal is the objective of the present study. Initial work has concentrated on the generation of a spectral database for each of six plants. These plants were selected because of their consumption by free-ranging sheep and cattle in the northern Chihuahuan Desert of the southwestern United States. The plants were collected from within the USDA AJornada Experimental Range in southern New Mexico. These plants include species of grasses (tobosa hay and mesa dropseed), forbs (spectacle pod and pale globemallow), and shrubs (tarbush and four-wing salt bush). The application of post-processing algorithms to these fluorescence emission spectra have also been pursued. Excitation of extract solutions from five plants of each species at 369 nm has yielded significant spectral signatures in the wavelength region of 400-600 nm.}, keywords = {dietary intake, livestock, measurements, multi-dimensional fluorescence}, author = {G.D. Rayson and T.L. Danielson and D.M. Anderson and Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @inbook {51111, title = {Drylands and global change: Rainfall variability and sustainable rangeland production}, booktitle = {Proceedings of the 12th Toyota Conference: Challenge of Plant and Agricultural Sciences to the Crisis of the Biosphere on the Earth in the 21st Century}, year = {2000}, note = {//NMSU,USDA//LTER III//ProCite field[6]: In}, month = {2000}, pages = {73-86}, publisher = {R. G. Landes Company}, organization = {R. G. Landes Company}, address = {Austin, Texas}, abstract = {This chapter reviews the extent of global change in drylands and some of its ecological and societal consequences. It also discusses rainfall variability as one component of potential climate change and how it affects primary production in rangelands. This is illustrated with a case study of a rangeland in southern New Mexico using a physiologically-based ecosystem model. It suggests that basic ecological knowledge should be an essential component of assessment frameworks.}, keywords = {book, books, chapter, chapters, climate variability, global change, desertification, global change, rainfall variability, global change, rangeland production, model, PALS, plant production, rainfall variability, rainfall, global change, rainfall, rangeland production, rangeland production, global change, report, reports}, author = {J. F. Reynolds and Roberto J. Fern{\'a}ndez and P. R. Kemp}, editor = {Watanabe, K. N. and Komanine, A. (eds.)} } @article {51142, title = {Demography of Bouteloua gracilis in a mixed prairie: analysis of genets and individuals}, journal = {Journal of Ecology}, volume = {87}, number = {2}, year = {1999}, month = {April 1, 1999}, pages = {233-243}, abstract = {

1 We analysed a data set containing the locations and sizes of individual plants from five 1-m2 permanent quadrats that had been mapped annually from 1934 to 1972. We digitized each map and used geographical information software to evaluate annual recruitment and mortality, age structure, survivorship and longevity of genets and individuals of Bouteloua gracilis.

2 Ninety-one per cent of the years between 1938 and 1972 had at least one seedling recruited. An average of 10.3 genets died annually, although the variability among years was high (CV\ =\ 70\%). The number of seedlings recruited each year was significantly correlated with the number of genets dying. Most genets died before age 10 and the average life span was 3.7 years, although some genets were much longer lived (\>\ 38 years).

3 The average number of individuals per genet was 1.3. Excluding seedlings, 56\% of the genets were represented by a single individual. The annual number of individuals in the 5\ m2 ranged from 29 to 278. Average mortality of individuals was 25.8 per year and the variability among years was high (CV\ =\ 91\%).

4 The plant community appeared to be relatively stable and openings created by mortality were recolonized by recruitment. Climatic variability did not have a large influence on demography.

}, keywords = {clonal fragmentation, grassland, mortality, plants, recruitment}, doi = {10.1046/j.1365-2745.1999.00344.x}, url = {/files/bibliography/653.pdf}, author = {J.L. Fair and W. K. Lauenroth and D.P. Coffin} } @inbook {51153, title = {Desert rangelands, degradation and nutrients}, booktitle = {Rangeland Desertification}, year = {1999}, month = {1999}, pages = {77-87}, publisher = {Kluwer Academic Press}, organization = {Kluwer Academic Press}, address = {Dordrecht, The Netherlands}, abstract = {

It is well recognized that rangeland environments, especially degraded environments, are relatively infertile. Though arid lands are moisture limited, it is often stated that they are nutrient regulated. A discussion of rangeland soil nutrients relative to landscape degradation should include: (1) dynamics of nutrient distributions; (2) soil properties affecting nutrient fluxes; (3) indicators of soil quality; and 4) nutrient based strategies for remediation. Nutrient distribution is strongly influenced by vegetation structure, and spatial nutrient patterns are closely linked to aspects of primary productivity and species composition. Effects of vegetation on nutrient spatial patterns can persist for decades, even if vegetation is altered by natural or anthropogenic disturbances. Though abiotic processes strongly shape physical features of arid landscapes, biotic activities directly affect soil nutrients. Unfortunately, assessment and monitoring technologies based on soil properties which quantify integrity of nutrient related processes have not been fully developed. Approaches for remediating degraded conditions need to exploit nutrient spatial and temporal heterogeneities. Remediation should be targeted to the most fertile sites, even if these are only relatively small parts of the overall landscape. Understanding nutrient dynamics is a key to triggering autogenic remediation of degraded rangelands.

}, keywords = {desert grassland, desertification, nitrogen, nutrient dynamics, phosphorus}, doi = {10.1007/978-94-015-9602-2_7}, url = {/files/bibliography/661.pdf}, author = {Kris Havstad and Jeffrey E. Herrick and W. H. Schlesinger}, editor = {Arnalds, O. and Steven R. Archer} } @conference {51158, title = {Decomposing the complexity of species coexistence patterns: an example from a semiarid grassland-shrubland transition zone}, booktitle = {5th World Congress, International Association for Landscape Ecology}, volume = {I (A-K)}, year = {1999}, month = {July 29-August 3}, pages = {67}, address = {Snowmass Village, Colorado}, abstract = {One of the greatest difficulties in species diversity studies is to understand the biotic and abiotic factors driving coexistence patterns at the landscape scale. Our objective was to decompose the complex patterns of species coexistence on a landscape into a multiscale, stratified mosaic of habitat types. We defined the structure of a number of factors (soil texture, kangaroo rat burrows and presence of dominant grasses or shrubs) at a grassland/shrubland ecotone in central New Mexico, USA and evaluated plant species diversity associated with each factor. We measured species diversity for each habitat type on the appropriate scale defined by each factor. Because the spatial pattern of soil texture was correlated with the other two factors, the effect of dominant plants and kangaroo rats could not be completely separated from effects of soils. We found important differences between the number and abundance of species coexisting with dominant grasses compared to shrubs. Species diversity was negatively correlated with the density of dominant plants, yet was positively related to burrowing activities of kangaroo rats. Our results demonstrate the importance of stratifying the landscape based on biotic and abiotic factors in order to distinguish the separate effects of each factor on species coexistence patterns.}, author = {Hochstrasser, T. and Debra C. Peters} } @conference {51174, title = {Disturbance and landscape change: Residential development and landscape structure in the Pikes Peak region, Colorado, USA}, booktitle = {5th World Congress, International Association for Landscape Ecology}, volume = {II (L-Z)}, year = {1999}, month = {July 29-August 3}, pages = {Abstract 114}, address = {Snowmass Village, Colorado}, abstract = {

Disturbances interact with biotic and abiotic landscape elements at multiple scales to drive changes in landscape structure. In turn, landscape structure affects the kinds, frequencies, intensities, and extent of disturbances actuated in the system. We analyzed the interactions of residential development as a disturbance with landscape structure to identify patch characteristics sensitive to disturbance, spatial and temporal trends in residential development, and the corresponding dynamics in landscape structural metrics. We sought to develop a model that would enable managers to use landscape structural change as an indicator of disturbances that could reverberate through multiple scales of ecological organization. Our approach was to use GIS linked with FRAGSTATS to detect trends in both residential development and landscape structural metrics. We further analyzed the potential impact of these trends on habitats and biodiversity. We found that patch desirability for development often coincides with patch ecological sensitivity. Development causes increased fragmentation and decreased connectivity of existing patches, with increased edge and clustering of both existing patch types and developed patches. Our results indicate that residential development changes landscape structure, associated wildlife habitats, and biodiversity. This information is critical for regional planning and management processes aimed at coexistence of natural and cultural components.

}, author = {Nasseth, D.L. and Debra C. Peters} } @inbook {51184, title = {Do landscape structural and functional units exist?}, booktitle = {Integrating Hydrology, Ecosystem Dynamics, and Biogeochemistry in Complex Landscapes}, year = {1999}, note = {//NMSU,USDA//LTER III//ProCite field[6]: InProCite field[36]: In}, month = {1999}, pages = {273-296}, publisher = {John Wiley and Sons}, organization = {John Wiley and Sons}, address = {Chichester, U.K.}, abstract = {

The complexity of landscapes requires that simplified constructs or frameworks be developed for understanding and predictions. Toward this goal, the question is posed, "Do landscape structural and functional units exist?" The argument is in favor of the existence of landscape units, but acknowledge that there are no generic recipes for simplifying the real world for use in landscape models. While simplification is the key to achieving understanding and prediction, explicit consideration of scale multiplicity in studying complex landscapes is dictated by the hierarchical properties of landscapes. Therefore, we suggest that the hierarchical patch dynamics paradigm provides a conceptual framework to accomplish these objectives.

}, keywords = {biogeochemistry, ecosystem dynamics, biogeochemistry, hydrology, book, books, chapter, chapters, hydrology, biogeochemistry, hydrology, ecosystem dynamics, landscape, biogeochemistry, landscape, ecosystem dynamics, landscape, hydrology, model, landscape, report, reports}, url = {files/bibliography/JRN00274.pdf}, author = {J. F. Reynolds and Jianguo Wu}, editor = {Tenhunen, J. D. and P. (eds.) Kabat} } @article {51187, title = {Diversity of arthropod responses to host-plant water stress in a desert ecosystem in southern New Mexico}, journal = {American Midland Naturalist}, volume = {142}, year = {1999}, note = {//NMSU//LTER III//}, month = {1999}, pages = {281-290}, abstract = {

Previous studies of insect-plant interactions have produced the contradictory Plant Stress Hypothesis (that stressed plants are more suitable hosts for phytophages) and Plant Vigor Hypothesis (that vigorous plants are more suitable hosts for phytophages). However, experimental studies of phytophage responses to host stress have involved only one, or a few, related phytophagous species, not whole communities of organisms associated with a particular plant species. We evaluated responses of various arthropods associated with creosotebush Larrea tridentata to manipulated water availability and plant stress in southern New Mexico during 1990-1991. Of 44 arthropod groups (taxa or functional groups) evaluated in our study only two taxa (including a lepidopteran folivore) showed significant negative response to water availability, thereby supporting the Plant Stress Hypothesis. Ten taxa (including eight phytophages) responded positively to water availability, supporting the Plant Vigor Hypothesis. One phytophage showed a nonlinear response, supporting neither hypothesis. Detrended Correspondence Analysis significantly distinguished the arthropod community on water-deprived shrubs from the communities on watered shrubs. The variation in responses among phytophagous insects on creosotebush indicated that the effect of plant water stress likely reflects the choice of phytophage, and perhaps the host plant, being studied. Therefore, neither the Plant Stress Hypothesis nor the Plant Vigor Hypothesis can explain responses of all phytophages on a particular plant species.

}, keywords = {arthropod, water stress, article, articles, Detrended Correspondence Analysis, insect, phytophagous, insect-plant interaction, journal, journals, phytophagous insect, Plant Stress Hypothesis, plant stress, arthropods, Plant Vigor Hypothesis}, doi = {10.1674/0003-0031(1999)142[0281:DOARTH]2.0.CO;2 }, url = {files/bibliography/JRN00273.pdf}, author = {Schowalter, T. D. and David C. Lightfoot and Walter G. Whitford} } @article {51207, title = {Disturbance intensity and above- and belowground herbivory effects on long-term (14 y) recovery of a semiarid grassland}, journal = {Plant Ecology}, volume = {139}, number = {2}, year = {1998}, month = {December 1, 1998}, pages = {221-233}, abstract = {

The importance of disturbance intensity and herbivory by cattle and white grubs, or the larvae of June beetles (including Phyllophaga fimbripes), to recovery of shortgrass steppe ecosystems in Colorado, U.S.A. were evaluated over a fourteen year time period. Disturbance intensity was defined by survival of the dominant grass species (Bouteloua gracilis) after an outbreak of root feeding activity by white grubs. Sixteen patches of vegetation consisting of four pairs of adjacent ungrazed-grazed by cattle locations with two replicates that were recently affected by white grubs were selected in 1977. Disturbance intensity was determined in 1977 by the area in each patch that contained live tillers of B. gracilis. Permanent plots were located both within and outside of each patch. Plant basal cover and density by species were estimated at time of peak aboveground biomass in six different years on each plot.

}, keywords = {Bouteloua gracilis, cattle grazing, june beetle larvae, root feeders, shortgrass steppe, succession}, doi = {10.1023/A:1009789017151}, url = {/files/bibliography/606.pdf}, author = {D.P. Coffin and Laycock, W.A. and W. K. Lauenroth} } @conference {51214, title = {Dispersal of Lehmann lovegrass by sheep}, booktitle = {Annual Meeting, Society for Range Management}, year = {1998}, month = {1998}, pages = {38}, abstract = {Lehman lovegrass seed are dispersed by wind and water; however, domestic animals also may be effective seed dispersal agents. Animal dispersion of Lehmann lovegrass has not been examined and was the objective of the present study conducted on the Jornada Experimental Range during the years 1995 and 1996. Two seed dispersal methods were evaluated: broadcasting and seed dispersal via sheep feces using two levels of precipitation. To determine treatment effects the following variables were measured: percentage of plots with Lehmann lovegrass seedlings, number of seedlings per plot and seedling vigor at the end of the growing season. The results showed that broadcast seeding produced three to four times more plots with Lehmann lovegrass seedlings than seed dispersed in sheep feces. The number seedlings per plot also were higher in broadcast seeded plots. Seedling vigor at the end of the growing season did not differ by seed dispersal method. Precipitation level did not effect the variables measured. Although not as effective as broadcast seeding, the germination and persistence of Lehmann lovegrass seeds in sheep feces does indicate that sheep should be considered as dispersal agents of Lehmann lovegrass.}, author = {Flores, M.A. and E.L. Fredrickson and Pieper, Rex D. and L. W. Murray} } @conference {51221, title = {Desert vegetation responses to natural and anthropomorphic stressors}, booktitle = {Annual Meeting of the Society for Range Management}, year = {1998}, month = {1998}, pages = {No. 7}, abstract = {

Disturbances in desert ecosystems can be either chronic or acute in effect, and natural or anthopomorphic in origin. We hypothesize that that severity of effects of an acute disturbance is shaped by ecosystem structure. We designed a long-term study to test this hypothesis. Within a grassland/shrubland ecotone we have applied livestock grazing (a 24 h defoliation of standing crop within a 365 d period) during either winter dormancy or summer growth periods. These grazing treatments are applied in either mesquite present or mesquite removed 0.5 ha inclosures. We expect that vegetation dynamics of the mesquite present treatment will demonstrate a threshold of mesquite at approximated 8\% canopy cover that will result in persistent shrub dominated community irrespective of season of defoliation.

}, author = {Kris Havstad and Walter G. Whitford and Gibbens, Robert P. and J.M. Lenz and Justin Van Zee and A.G. de Soyza} } @inbook {51257, title = {The desert grasslands}, booktitle = {Ecosystem Health}, year = {1998}, month = {1998}, pages = {313-323}, publisher = {Blackwell Science, Inc.}, organization = {Blackwell Science, Inc.}, chapter = {20}, address = {Malden, MA}, abstract = {

The desert grasslands are widely distributed in North America, occupying much of southeastern Arizona, the southern half of New Mexico, and west Texas in the United States and extending southward through 13 states in Mexico, from Sonora to Puebla. They represent more than 500,000 km2 of basin and valley lands that skirt the hills and mountain ranges of southwestern North America (McClaran 1995). The entire geographic range of the desert grasslands has seen a rapid decline in grass cover and an increase in cover by woody shrubs, especially mesquite (Prosopis spp.) and creosotebush (Larrea tridentata). Traditionally, the desert grasslands have supported extensive stands of perennial bunch grasses, known colloquially as the grama grasses, which reproduce primarily by stolons. Other, smaller bunch grasses occupied habitat patches such as infrequently inundated swales that support a cover of tabosa grass, Hilaria mutica.

}, url = {/files/bibliography/639.pdf}, author = {Walter G. Whitford}, editor = {D. J. Rapport and Costanza, R. and Epstein, P.R. and C. Gaudet and Levins, R.} } @article {51264, title = {Disturbance of biological soil crusts: Impacts on potential wind erodibility of sandy desert soils in southeastern Utah, U.S.A.}, journal = {Land Degradation and Rehabilitation}, year = {1997}, note = {//?//LTER III//}, month = {1997}, abstract = {

Friction threshold velocities (FTVs) were determined for biological soil crusts in different stages of recovery. Particles on the surface of crusts that had been relatively undisturbed for at least 20 years were found to have significantly higher FTVs than those that had been disturbed 5, 10 or 1 years previously (376, 87, and 46 cm sec-1, respectively). FTV{\textquoteright}s for crust breakage was also much higher for undisturbed crusts when compared to the previously disturbed crusts (573, 148, and 88 cm sec-1, respectively). All crusted surfaces were more stable than bare sand, which had an FTV of 16 cm sec-1. Disturbance treatments were then applied to the three crustal classes. Disturbance significantly reduced the FTVs of all classes by 73{\textendash}92 per cent. Comparing crustal FTVs with mean and high monthly wind speeds found in this region, it was observed that only crusts that had been undisturbed for approximately 20 years or more were able to protect soil surfaces from wind gusts expected on the average of once a month. Other crustal classes, as well as all disturbance treatments, had FTVs lower or equal to that of commonly occurring winds in this region. Because most of the crustal biomass occurs in the top 0{\textperiodcentered}3 mm of soils, even slight soil loss can negatively influence stability and nutrient inputs to this ecosystem.

}, keywords = {article, articles, cryptobiotic crust, journal, journals, soil crust, soil erosion, soil properties, soil,biota, wind erosion}, doi = {10.1002/(SICI)1099-145X(199712)8:4<355::AID-LDR266>3.0.CO;2-H}, url = {files/bibliography/JRN00235.pdf}, author = {Jayne Belnap and D. E. Gillette} } @book {51299, title = {Defining plant functional types for models of desertification}, series = {Plant Functional Types}, year = {1997}, note = {//NMSU, USDA//LTER III//ProCite field[6]: In}, month = {1997}, pages = {195-216}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {book, books, chapter, chapters, desertification, model, model, desertification, report, reports}, author = {J. F. Reynolds and R. A. Virginia and W. H. Schlesinger}, editor = {Smith, T. M. and Shugart, H. H. and Woodward, F. I. (eds.)} } @article {51313, title = {Desertification and animal biodiversity in the desert grasslands of North America}, journal = {Journal of Arid Environments}, volume = {37}, year = {1997}, month = {1997}, pages = {709-720}, abstract = {

Studies of breeding birds and small mammals were conducted at a series of sites that form a gradient of severity of desertification. Desert grassland sites represented the least changed landscape units and mesquite coppice dunes represented the most severe degradation, an irreversibly degraded landscape unit. The hypothesis that desertification reduces species diversity was not supported by the data. Species richness and diversities (Shannon-Weaver H') of breeding birds were higher in the desertified areas than in the grassland with one exception. Data from a site dominated by the exotic African grass, Eragrostis lehmanniana, in south-eastern Arizona showed that breeding bird diversity was lower at that site than at a site in the same region that was dominated by native grasses. Species richness, diversity (H'), and abundance of small mammals were also higher in desertified areas than in desert grassland. Most grassland species of birds and mammals persist in the desertified habitats and species that are characteristic of shrublands colonize desertified desert grasslands. This accounts for the increases in species richness. However some species such as the banner-tailed kangaroo rat, Dipodomys spectabilis, are eliminated when grassland degrades to mesquite coppice dune or eroded creosotebush communities. These data suggest that other measures of faunal biodiversity such as keystone species may be better measures of the impact of desertification on animal biodiversity.

}, keywords = {biodiversity, breeding birds, desert grasslands, desertification, exotic species, rodents}, doi = {10.1006/jare.1997.0313}, url = {/files/bibliography/600.pdf}, author = {Walter G. Whitford} } @conference {51312, title = {Desertification and biodiversity}, booktitle = {International Symposium and Workshop Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {May 12-16, 1997}, pages = {Abstract 44}, address = {Tucson, AZ}, abstract = {

Desertification is widely recognized as causing dramatic and frequently irreversible changes in the composition and cover of vegetation and loss of soil and soil productivity. Conventional wisdom holds that such change should result in equally dramatic changes in faunal biodiversity. Intensive study of breeding birds, winter birds, ant communities, soil microarthropods, small mammals, and ground arthropods failed to provide clear or consistent patterns that could be related to the degree of degradation and/or exposure to chronic anthropogenic stressors. We examine the problem of measurements of faunal biodiversity in rangeland ecosystems. Measurements that include data on keystone species, critical link species, exotic and alien species, and distribution of life forms may provide better assessment opportunities and have the potential for incorporation into monitoring systems. Examples of these data are given for Chihuahuan Desert ecosystems.

}, author = {Walter G. Whitford and P.U. Alkon and W. E. Smith and Justin Van Zee} } @conference {51314, title = {Development of arid rangeland remediation approaches: community participation in research}, booktitle = {International Symposium and Workshop Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {May 12-16, 1997}, pages = {Abstract 79}, address = {Tucson, AZ}, author = {J. A. Winder and Jeffrey E. Herrick and E.L. Fredrickson and Kris Havstad and J.R. Barrow} } @article {51316, title = {Differences in ewe and wether behavior when bonded to cattle}, journal = {Applied Animal Behaviour Science}, volume = {47}, year = {1996}, note = {Reprinted with permission from Elsevier, {\textcopyright} 1996. http://www.sciencedirect.com/science/journal/01681591}, month = {1996}, pages = {201-209}, abstract = {

Under mixed stocking, both intra- and inter-species associations exist. Sheep normally do not associate with cattle when the two species are grazed together. However, sheep can be made to consistently stay close to (bond) and follow cattle if forced in close association with cattle at an early age for a period of time. The cohesiveness of this inter-species association under free-ranging conditions varies due to many factors, including sheep gender. Bonded wethers stay nearer to cattle than do bonded ewes. However, the distance of separation between bonded sheep groups and cattle groups during grazing increases over time. Though the mechanism(s) for these phenomena are not presently understood, keeping a few bonded wethers with bonded ewes may enhance the establishment and maintenance of consistently coherent range flerds (flocks + herds).

}, keywords = {cattle, grazing, predation, sheep, social grouping}, doi = {10.1016/0168-1591(95)00676-1}, url = {/files/bibliography/465.pdf}, author = {D.M. Anderson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and R. Libeau and L. W. Murray} } @article {51348, title = {Dung decomposition and pedoturbation in a seasonally dry tropical pasture}, journal = {Biology and Fertility of Soils}, volume = {23}, year = {1996}, month = {August 1996}, pages = {177-181}, abstract = {

Rates of dung decomposition and the associated accumulation of soil transported to the surface were compared for dung deposited during a dry and a wet season in a Costa Rican pasture. Average decomposition rates for the first 140 days after deposition were significantly lower for dung patches deposited at the beginning of the dry season than for patches deposited at the beginning of the wet season (0.73 vs. 1.50 g/day-1 on a dry weight basis). A strong linear relationship was found between dung removal and soil accumulation at the original soil surface, with an average of 2.0 g soil accumulated for every gram of dung which was removed. This relationship was not affected by deposition season. The lack of a seasonal difference, along with the relatively low decomposition rates during the wet season, were explained by the dominance of termites in the dung patches throughout the year. Evidence of dung beetle activity was never recorded during the dry season and was found in only 18 of the 45 dung patches recovered during the wet season.

}, keywords = {Cattle dung, decomposition, Pedoturbation, soil restoration, termites, Tropical pastures}, doi = {10.1007/BF00336060}, url = {/files/bibliography/491.pdf}, author = {Jeffrey E. Herrick and Lal, L.} } @proceedings {51383, title = {Dynamics of carbon storage in degraded arid land environments: a case study from the Jornada experimental range, New Mexico, (USA)}, year = {1995}, note = {//NMSU,USDA//LTER III//ProCite field[6]: In}, month = {1998}, pages = {132-148}, publisher = {The University of Arizona Press}, address = {Nairobi, Kenya}, abstract = {This paper reviews spatial and temporal dynamics of carbon storage related to Holocene climatic change and recent shrub invasion (due to desertification) in the Jornada Basin, New Mexico (USA). It evaluates the role of regional climate history, vegetation distribution, and soil characteristics as controls on carbon cycling in this system. Ecosystem-level changes in above- and below-ground carbon pools in grassland and desertified shrub communities are compared to quantify changes in the net carbon balance associated with desertification. An assessment is made, in the context of the Jornada desertification model, of the potential opportunities to sequester carbon in drylands and to identify current research needs.}, keywords = {abstract, abstracts, carbon storage, soil, carbon, model, conference, conference proceedings, conferences, desertification, model, global change, carbon sequestration, model, desertification, proceeding, proceedings}, author = {S. L. Connin and R. A. Virginia and Chamberlain Page and L. Huenneke and Harrison, Kevin and W. H. Schlesinger}, editor = {Squires, Victor R. and Glenn, Edward P. and Ayoub, Ali T. eds.} } @conference {51386, title = {Detection of temporal changes in shrub densities using meteorological satellite data}, booktitle = {Wildland Shrub Symposium}, year = {1995}, month = {May 23-25, 1995}, pages = {23}, abstract = {In 1988, personnel with the Jornada Experimental Range in southern New Mexico chemically treated a large grassland area for mesquite. he treatment was successful in killing nearly 100\% of the mesquite plants present. Since treatment plant recovery and invasion has resulted in current mesquite densities of about 3\% cover. We accessed 90 dates of vegetation index information derived from meteorological satellite imagery recorded over seven growing seasons. The data were used to track the density of mesquite from pre-treatment through five years post-treatment. Differences in seasonal landscape greenness characteristics derived by analysis of the satellite data show the effect of the chemical treatment, as well as the re-invasion of the mesquite. This research demonstrates the potential utility of satellite derived information in assessing vegetation response to implementation of range management strategies. Similar techniques applied over longer time periods could be utilized to monitor ecosystem health and desertification processes.}, author = {M.D. Eve and Peters, A.J.} } @article {51411, title = {On definition and quantification of heterogeneity}, journal = {Oikos}, volume = {73}, number = {2}, year = {1995}, note = {//OTHER//LTER III//}, month = {1995}, pages = {280-284}, abstract = {

General guidelines on the quantitative representation of heterogeneity in ecology are still lacking. Without a precise definition and sound quantification of heterogeneity, statements involving the concept will continue to be confusing, and comparative studies and hypothesis testing will be ineffective. To solve this problem we propose an operational definition of ecological heterogeneity that facilitates quantification based on the data types of concern. We use two examples to demonstrate how our definition and quantification of spatial heterogeneity can be applied in practice.

}, keywords = {article, articles, heterogeneity, journal, journals, model, spatial heterogeneity, spatial heterogeneity}, doi = {10.2307/3545921}, url = {files/bibliography/JRN00192.pdf}, author = {Harbin Li and J. F. Reynolds} } @article {51414, title = {Decomposition processes: Modelling approaches and applications}, journal = {Science of the Total Environment}, volume = {183}, year = {1995}, note = {//??//LTER III//}, month = {1995}, pages = {137-149}, abstract = {

Decomposition is a fundamental ecosystem process, strongly influencing ecosystem dynamics through the release of organically bound nutrients. Decomposition is also a complex phenomenon that can be modified by changes in the characteristics of the decaying materials or prevailing environmental conditions. For these reasons, the impacts of local, regional or global environmental changes on the quality and turnover of dead organic matter are of considerable interests. However, realistic limits to the complexity, as well as temporal and spatial scales, or experimental studies restrict their usefulness in extrapolating long-term or large-scale results of simultaneous environmental changes. Alternatively, many simulation models have been constructed to gain insight to potential impacts of anthropogenic activities. Because structure and approach determine the strengths and limitations of a model, they must be considered when applying one to a problem or otherwise interpreting model behaviour. There are two basically different types of models: (1) empirical models generally ignore underlying processes when describing system behaviour, while (2) mechanistic models reproduce system behaviour by simulating underlying processes. The former models are usually accurate within the range of conditions for which they are constructed but tend to be unreliable when extended beyond these limits. In contrast, application of a mechanistic model to novel conditions assumes only that the underlying mechanisms behave in a consistent manner. In this paper, we examine models developed at different levels of resolution to simulate various aspects of decomposition and nutrient cycling and how they have been used to assess potential impacts of environmental changes on terrestrial ecosystems.

}, keywords = {article, articles, decomposition, model, journal, journals, model, decomposition}, doi = {10.1016/0048-9697(95)04974-6}, url = {files/bibliography/JRN00185.pdf}, author = {Daryl L. Moorhead and Sinsabaugh, R. and Linkins, A. E. and J. F. Reynolds} } @mastersthesis {51384, title = {Detailed soil survey of the Jornada LTER (Long Term Ecological Research) transect vicinity, southern New Mexico}, year = {1995}, note = {//NMSU//LTER III// Date sent: Thu, 14 Sep 2000 15:48:02 -0600To: "John Anderson"From: Monger Subject: Re: Pubs by Rojas?Well....... Not yet. We have one manuscript on my desk looking me in the face, but it hasn{\textquoteright}t been submitted for publication yet. So, for now all we have is the M.S. thesis.See you,CurtisProCite field[12]: Abstract only}, month = {1995}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {This study presents a detailed soil map of the upper portion of the Jornada LTER site on the bajada between Summerford Mountain and College Playa. It also offers an explanation why some dark soils in the Summerford grassland give a false impression of high organic matter. The purpose of this study is to help LTER scientists better understand the flora and fauna distribution on the LTER site, which are greatly affected by soil variability. The study consisted of two parts: the field study and the laboratory analysis. For the field study, aerial photography was used in conjunction with field observations, which included describing soil profiles in hand-dug pits and with a soil auger. Data for laboratory analysis were collected from 17 pedons along the upper LTER I transect, which extends from the Summerford grassland at the base of the northern Dona Ana Mountains downward tothe New Mexico State University College Playa. Laboratory analysis included organic carbon, calcium carbonate, particle size distribution and pH. The 17 sites were selected based on topography, soil color and vegetation patterns. Seven pedons were placed in the Summerford grassland area and compared to ten pedons downslope from the grassland along the LTER transect. In addition to the aridic moisture regime criterion, soils were classified based on the presence of the following diagnostic horizons: mollic, ochric, cambic, argillic and calcic. Two soil order were classified in the study area: Mollisols and Aridisols. Mollisols occur in the upper part of the Summerford grassland where mollic epipedons occurs as deep A horizon with high accumulation of organic matter. They include Aridic Haplustolls, Aridic Argiustolls, and Torriorthentic Haplustolls. Aridisols occur downslope where shrubs become more predominant. These include Typic Haplargids, Typic Haplocambids, Typic Haplocalcids, Ustic Haplargids and Ustic Haplocambids. For the family differentiate, all pedons described have a coarse-loamy particle-size class. The mineralogical and the soil temperature classes are mixed, thermic based on correlation to previous studies. To determine why some soils in the Summerford grassland had a false impression of high organic carbon content, thin sections were made by impregnating peds with blue-epoxy, and observing them with a polarized microscope. The false impression of high organic carbon content was found to be a result of most of the organic matter occurring as a thin coating on gravels and sand grains with very low organic matter in the pore spaces. Although the coating make up a small percentage of soil by weight, they effectively darken the horizon.}, keywords = {dissertation, dissertations, soil carbon, soil mapping, soil properties, soil survey, soil texture, soil, aridisols, soil, boundaries, soil, cambic horizon, soil, classification, soil, description, soil, geomorphology, soil, K horizon, soil, landscape, soil, morphology, soil, organic carbon, soil, spatial variability, theses, thesis}, author = {Encina Rojas, Arnulfo} } @article {51428, title = {Desertification: Implications and limitations of the ecosystem health metaphor}, volume = {I(28)}, year = {1995}, month = {1995}, pages = {273-292}, abstract = {

The semi-arid and arid regions of the world may provide some valuable insights into the applicability of the ecosystem {\textquotedblleft}health{\textquotedblright} and ecosystem {\textquotedblleft}medicine{\textquotedblright} metaphors. These regions provide an example of the applications and limitations of the metaphor because they have experienced and continue to experience degradation and change. Attempts at rehabilitation of degraded areas has proven to be expensive or impossible. Those parameters that are frequently examined to determine the {\textquotedblleft}health{\textquotedblright} of ecosystems may be more robust in ecosystems that are generally considered to be degraded than in those perceived as healthy. Most such areas have suffered loss of productivity as measured by the capacity to support livestock and human inhabitants. Those losses in livestock productivity resulted from changes in the biological and physical characteristics of the ecosystems within these regions.

}, doi = {10.1007/978-3-642-79464-3_17}, url = {/files/bibliography/JRN00186.pdf}, author = {Walter G. Whitford}, editor = {D. J. Rapport and C. Gaudet and P. (eds.) Calow} } @inbook {51431, title = {Diversity, spatial variability, and functional roles of invertebrates in desert grassland ecosystems}, booktitle = {The Desert Grassland}, year = {1995}, note = {//NMSU, USDA//LTER III//ProCite field[6]: In}, month = {1995}, pages = {152-195}, publisher = {University of Arizona Press}, organization = {University of Arizona Press}, address = {Tucson, AZ}, abstract = {

Any analysis of the community structure and functional roles of desert grassland invertebrates is constrained by the fact that there are few, if any, patches of grasslands undisturbed by humans and their domestic livestock. The desert grasslands currently exist as scattered patches surrounded by large expanses of desertscrub or as a grassland matrix with shrubs. Much of the area that was desert grassland in the 1850s is now classified as desertscrub (Buffington and Herbel 1965; York and Dick-Peddie 1969). Further, the remaining desert grassland remnants are diverse in terms of soil characteristics and grass species composition. In some areas, exotic introduced grasses have become dominant; in others, remnant grasslands are dominated by species of grasses that are relatively unpalatable to domestic livestock. The invertebrate fauna of desert grasslands is incredibly diverse and includes several phyla. while mammal, bird, reptile, and vascular plant species occur in the tens to hundreds, invertebrate species in desert grasslands number in the thousands or tens of thousands, and many of the less conspicuous species have never been described by taxonomists. Much of this fauna is never seen by the casual observer. If you were asked, "What invertebrates did you see on your morning walk in the desert grassland?" your response would probably be "ants." Ants are the most conspicuous and, along with unseen subterranean termites, the most numerous macroinvertebrates in arid environments. However, the fauna of desert grasslands includes many microscopic organisms and many large but cryptic species as well as the obvious and familiar ones (Crawford 1981; Wallwork 1982). Most of what we know about desert grassland invertebrates and their general life history characteristics is based on data from economically important species (Crawford 1981).

}, keywords = {biodiversity, invertebrates, book, books, chapter, chapters, ecosystem dynamics, invertebrates, grassland, invertebrate community, invertebrate community, invertebrate,grassland, report, reports}, url = {files/bibliography/JRN00188.pdf}, author = {Walter G. Whitford and Gregory S. Forbes and G. I. H. Kerley}, editor = {M.P. McClaran and T.R. Van Devender} } @article {51455, title = {Desert dwelling small mammals as granivores: intercontinental variations}, journal = {Austrialian Journal of Zoology}, volume = {42}, year = {1994}, note = {//NMSU,USDA//LTER-III//}, month = {1994}, pages = {543-555}, abstract = {

Deserts are, by definition, environmentally similar, and this has lead to hypotheses of convergence in the properties of desert biotic communities as well as the components of these communities. There is considerable evidence for convergence in some characteristics of desert biota, ranging from plant growth forms to the well-known bipedal, nocturnal rodents. One area that has received considerable attention has been granivory by desert rodents, largely because of the effort focused on the North American desert heteromyids, and also because the process of granivory has far-reaching ramifications for desert plant communities. Specific tests for convergence in the impact of rodents as granivores, by means of bait-removal experiments, however, have shown that the high levels of seed removal by rodents in the North American deserts differs from that of rodents in the South American, Australian and South African deserts, where ants are the most important seed harvesters. The only studies to measure the impact of rodents on desert seed fluxes confirm these patterns, with rodents consuming up to 86\% of seed production in North American deserts, but less than 1\% of seed production in South African deserts. A review of dietary data for desert rodents confirms these trends, with little evidence for the presence of granivores in deserts besides those of North America. A variety of hypotheses have attempted to explain these variations in desert rodent granivory. These include recent extinctions of granivores, that seed burial, low soil nutrients and/or limiting seed production prevented the radiation of granivorous small mammals, and that particular deserts are too young or too recently colonised by rodents for granivorous rodents to have evolved. However, none of these hypotheses are supported by available evidence. Alternative hypotheses suggesting that climate variability may have precluded the development of specialised granivores need to be tested. In particular, more data are needed to confirm these patterns of granivory, and gain an understanding of the effects of Pleistocene and recent desert climate variability on seed production. An alternative perspective suggests that the presence of the heteromyid rodents may explain the high levels of granivory by small mammals in North American deserts. The variability in granivory by small mammals between deserts suggests that deserts will also differ in terms of anti-granivore adaptations of plants, seed fluxes and the mechanisms whereby small mammals coexist.

}, keywords = {article, articles, journal, journals}, doi = {10.1071/ZO9940543}, url = {files/bibliography/94-AusJrnlofZoology-Whitford.pdf}, author = {G. I. H. Kerley and Walter G. Whitford} } @mastersthesis {51506, title = {Diurnal diet composition and behavior of cattle and sheep on Chihuahuan Desert range}, volume = {PhD}, year = {1993}, note = {Available in JER Library}, month = {1993}, pages = {162 }, school = {New Mexico State University}, type = {Dissertation }, address = {Las Cruces}, keywords = {behavior, cattle, Chihuahuan Desert, diet composition, dissertation, diurnal, research notes, sheep}, author = {J. N. Smith} } @conference {51511, title = {Determining botanical composition of free-ranging animal diets using physical properties of fecal material}, booktitle = {Annual Meeting, Society for Range Management}, year = {1992}, month = {1992}, pages = {P097}, abstract = {Techniques for sampling plants or animals to determine botanical composition of free-ranging livestock diets are tedious and costly. Estimates of diet selection using animal rather than agronomic techniques should provide the most accurate data for management of range livestock. Microhistological analysis of masticate and fecal material has been used extensively to determine diet quality in free-ranging herbivores. However, the major limitation with procedures requiring microscopic analysis is the time required for training, preparation and identification. We propose that physical properties of fecal material, including water adsorption and particle size distribution, may be useful in identifying animals within a species with higher proportions of browse in their diets. Preliminary analyses of dried Angora goat feces collected from animals housed in metabolism stalls indicates feces derived solely from monocots imbibed 63\% less water than feces from animals consuming a mixture of monocots and dicots. Data will be presented on additional analyses of other physical properties and more specific dietary components. Determination of inexpensive and rapid yet accurate techniques to separate herbivore diets into grasses, forbs and browse components would be a valuable tool for both scientific and management purposes.}, author = {D.M. Anderson and Kris Havstad and Richard E. Estell and E.L. Fredrickson and L. W. Murray} } @proceedings {51513, title = {Desert soils and soil biota}, year = {1992}, note = {//OTHER//LTER II//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: In}, month = {1992}, publisher = {Latting Press}, keywords = {abstract, abstracts, California,soil biota, conference, conference proceedings, conferences, proceeding, proceedings, soil,biota}, author = {Bainbridge, D. A. and R. A. Virginia}, editor = {Latting, J. (ed.)} } @article {51532, title = {Diet selection of cattle and bonded small ruminants grazing arid rangeland}, journal = {Sheep Research Journal}, volume = {8}, number = {1}, year = {1992}, month = {1992}, pages = {11-18}, abstract = {

Cattle, sheep and goats, when together on the same range are referred to as grazing in common, or as being managed under mixed grazing (Allen, 1991). Most mixed grazing schemes are designed to take advantage of dietary differences among livestock species. Grazing strategies involving more than one animal species should promote more uniform forage utilization and greater livestock production than is possible under single species grazing (Anderson et al., 1985).

}, keywords = {goats, grazing behavior, liveweight, microhistological analysis, Mixed stocking, sheep}, url = {/files/bibliography/389.pdf}, author = {Clarence V. Hulet and D.M. Anderson and V.B. Nakamatsu and L. W. Murray and Pieper, Rex D.} } @book {51534, title = {Desertification}, series = {Encyclopedia of Earth Science}, year = {1992}, note = {//??//LTER II//Listed in LTER3 proposal as citing LTER2 support// Updated 12/17/2005ProCite field[6]: In}, month = {1992}, publisher = {Academic Press}, organization = {Academic Press}, address = {San Diego}, keywords = {book, books, chapter, chapters, desertification, report, reports}, author = {W. M. Jarrell} } @conference {51554, title = {Defoliating tarbush under multispecies management}, booktitle = {4th US/Mexico Border Conference on Recreation, Parks and Wildlife}, year = {1991}, month = {May 1-3, 1991}, abstract = {Tarbush (Flourensiacernua DC.) is a native, perennial, deciduous, warm-season shrub that grows on fertile clay loam soils of the Chihuahuan Desert. Blooming tarbush has been shown to be toxic to ruminants; however, vegetative tarbush can be safely browsed. Under conventional grazing strategies tarbush seldom exceeds 13\% of free cattle, sheep and domestic goat diets. Past management practices have encouraged elimination of tarbush by mechanical or chemical means. In an attempt to increase tarbush defoliation, cattle, sheep and Spanish and Angora goats (8:2017:2; 23 AU/ha) were combined to stock 8 0.6 ha paddocks, 4 at a time, over 28 d. Animals were periodically observed to document diets using a modified bite-count technique. Mean annualtarbush leaf, flower and twig production was 385 kg/ha based on 20 plants adjacent to the paddocks that were harvested and separated. Some tarbush received detectable use within the first 48 hours. Defoliation on 120 randomly chosen, individual plants ranged from 5 to 99\%. The mean vegetative position of the eight paddocks was 30\% grasses, 6\% forbs and 11\% shrubs other than tarbush. Sheep lost weight (2.3 to 3.0 kg/hd) and body condition (0.8 units), regardless of paddock. Goat body condition did not change overall. Overall, cattle, sheep and Spanish and Angora goat diets were 48, 67, 82 and 84\% tarbush, respectively. Short intervals of high-density multispecies stocking reduced tarbush foliage. No health problems were observed in any of the animal species. However, unique plant and animal differences existed which affected tarbush use.}, author = {D.M. Anderson and Gibbens, Robert P. and Clarence V. Hulet and Kris Havstad and Richard E. Estell} } @article {51559, title = {On determining the statistical significance of discontinuities within ordered ecological data}, journal = {Ecology}, volume = {72}, number = {6}, year = {1991}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1991}, pages = {2057-2070}, abstract = {

Current ecological theory hypothesizes that boundaries between adjacent ecosystems units are important in determining ecosystem structure and function across heterogeneous landscapes, and that such boundaries are potentially important sites for early detection of global climate change effects. Hence, there is an increasing research effort to elucidate the structure and function of ecological boundaries. Yet traditional data analysis methods focus primarily on homogeneous units rather than on the boundaries between them; thus, new methods are being developed for detecting, characterizing and classifying boundaries, e.g., split moving-window boundary analysis (SMW). SMW is a simple yet sensitive method for locating discontinuities that may exist within multivariate, serial data (ordered in one dimension) at various scales relative to the length of the data series. However, SMW is subjective and relative, and therefore locates apparent dicontinuities even within random, serial data. In this paper we present two nonparametric methods for determining the statistical significance of discontinuities detected by SMW. First, we describe a Monte-Carlo method for determining the statistical significance of scale-dependant discontinuities (i.e., discontinuities that are significant relative to only one scale). Second, we propose a nonparametric, scale-independent method (it also is dependent upon scale size, but to a much lesser degree than the Monte Carlo method) that is more appropriate for locating statistically discontinuities that separate different, relatively homogeneous groups of varying size along a series. We examine the robustness of these two methods using computer-generated data having varying intensities of imposed discontinuities, and illustrate their application to locating boundaries between vegetation samples collected at systematic intervals across a desert landscape in southern New Mexico, USA.

}, keywords = {article, articles, journal, journals, model,boundary analysis, model,Monte Carlo simulation, statistical methods, technique,ecosystem boundary analysis, transect,ecosystem boundaries, transect,spatial discontinuities, transect,vegetation boundaries, vegetation, ecosystem boundaries, vegetation,spatial pattern}, doi = {10.2307/1941559}, url = {files/bibliography/JRN00137.pdf}, author = {Joe M. Cornelius and J. F. Reynolds} } @article {51560, title = {The distribution of vascular plant species and guilds in space and time along a desert gradient}, journal = {Journal of Vegetation Science}, volume = {2}, year = {1991}, note = {//NMSU//LTER II//Journal - Short//}, month = {1991}, pages = {59-72}, abstract = {

We studied distribution patterns of vascular plant species and environmental variables for three years along a permanent transect traversing a closed-drainage watershed in the northern Chihuahuan Desert of south-central New Mexico, USA. The transect extended for 2.7 km from a basin floor playa (1310 m elevation, fine-textured soil), across a piedmont slope, and onto the base of a granitic mountain (1410 m elevation, coarse-textured soil). The gradients in elevation and soils across our transect, along with variable seasonal rainfall, downslope redistribution of water and organic matter, and soil texture-related variation in infiltration, water holding capacity, and moisture release characteristics, interact to generate a complex spatial and temporal gradient of available soil water and nitrogen. We grouped plant species into guilds according to growth form and photosynthetic pathway type. These guilds are spatially and temporally differentiated along the transect such that particular groups utilize particular seasonal phases or spatial regions of the gradient. We identified six distinct plant communities along the transect. C4 perennial grasses dominated the mesic/high nitrogen portion of the gradient, which occurred at the highest (upper piedmont grassland, dominated by Bouteloua eriopoda) and lowest (playa, dominated by Panicum obtusum) elevations along the transect. C3 shrubs were dominant in the xeric/low nitrogen portion of the gradient located near the middle of the transect (bajada shrubland, dominated by Larrea tridentata). C3 shrubs also dominated a narrow zone of vegetation located adjacent to the playa (playa fringe, dominated by Prosopis glandulosa). C4 perennial grasses, C3 subshrubs, and C3 and C4 perennial forbs and annuals were co-dominant in the intermediate locations along the gradient, which occurred below (mixed basin slopes), and above (lower piedmont grassland) the bajada shrubland. Life-form distribution patterns at the small scale of our study reflect some of the patterning that occurs at larger scales in response to climate gradients. The distributions of some species and guilds along the transect are apparently modified by competitive interactions.

}, keywords = {article, articles, community classification, gradient analysis, growth form, journal, journals, photosynthetic pathway, plant community,classification, transect,community classification, transect,plant distribution}, doi = {10.2307/3235898}, url = {files/bibliography/JRN00142.pdf}, author = {Joe M. Cornelius and P. R. Kemp and J. Ludwig and Gary L. Cunningham} } @article {51596, title = {Dependence of standing crop on range condition rating in New Mexico}, journal = {Journal of Range Management}, volume = {44}, year = {1991}, note = {//??//NONE//}, month = {1991}, pages = {602-605}, keywords = {article, articles, journal, journals, range management, rangeland,condition rating}, author = {Tiedeman, J. A. and Reldon F. Beck and Ecret, R. V.} } @article {51601, title = {Diet selection of bonded and nonbonded free-ranging sheep and cattle}, journal = {Applied Animal Behavior Science}, volume = {26}, year = {1990}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1990. (http://www.sciencedirect.com/science/journal/01681591)}, month = {1990}, pages = {231-242}, abstract = {

Compared with monospecies stocking, numerous studies substantiate that multispecies stocking can efficiently increase use within and among the mosaic pattern of rangeland plant life forms. However, multispecies stocking may fail to bring anticipitated biological and financial results because of severe small ruminant losses, often because of coyote (Canis latrans) predation. Previously published data have demonstrated that when young lambs are bonded to cattle, they will follow cattle under free-ranging conditions. This close association under free-ranging conditions has been shown to reduce coyote predation on lambs. However, in addition to protection, lambs that stay with cattle may have their diet selection influenced. Differences between cattle and sheep diets were estimated using microhistological analysis of heifer and lamb feces. The data indicated differences between pastures, animal species, and bonded and non-bonded lamb diets. Lambs bonded to cattle grazed 7\% more grass, 5\% fewer forbs and 4\% fewer shrubs between April and June than non-bonded lambs. Cattle diets were not influenced by either bonded or non-bonded lambs grazing in the same pasture and averaged 57\% grass, 35\% forbs and 8\% shrubs. In contrast, bonded sheep diets averaged 35\% grass, 59\% forbs and 5\% shrubs. The relatively large differences between heifer and lamb diets, and the relatively small differences between bonded and non-bonded lamb diets, do not negatively impact the potential benefits to be gained from multispecies stocking using bonded sheep. Managing bonded sheep with cattle under free-ranging conditions may result in more uniform spatial use of the vegetation than would occur if either species were managed alone.

}, doi = {10.1016/0168-1591(90)90139-5}, url = {/files/bibliography/352.pdf}, author = {D.M. Anderson and Clarence V. Hulet and Hamadeh, S.K. and J. N. Smith and L. W. Murray} } @article {51609, title = {Decomposition patterns of surface leaf litter of six plant species along a Chihuahuan Desert watershed}, journal = {The American Midland Naturalist}, volume = {123}, number = {2}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {319-330}, abstract = {

Mass losses from litter bags of surface creosote bush litter placed along a Chihuahuan Desert watershed were measured to answer the following questions: (1) Do edaphic factors affect organic matter losses? (2) Are there differences in mass losses between the litter of the site-dominant plant species and creosote bush leaf litter? We hypothesized that (1) mass losses of all litter types would be higher at the base of the watershed and lower on the upper portions of the watershed and (2) mass losses of the litter of the site-dominant plants would be higher than those of creosote bush leaf litter in the same site. Mass losses from creosote bush leaf litter did not follow the moisture-organic matter gradient present in the watershed. Mass losses where higher at mid-slope run-on areas than in upper-slope erosional sites and the dry lake basin. Mass losses were highest where subterranean termite activity was the highest. There were differences between losses from the litter of the site-dominant and creosote bush leaf litter in some instances, but these differences were not attributable to differences in lignin content nor C:N ratio. Mass losses of litter of site-dominant species were not always higher than that of creosote bush leaf litter in the same site. Mass losses were best described by the double exponential model.

}, keywords = {article, articles, decomposition, Larrea, decomposition,litter, journal, journals, Larrea, decomposition, litter, decomposition, litter,also SEE , shrub, Larrea, transect,litter decomposition}, doi = {10.2307/2426560 }, url = {files/bibliography/JRN00119.pdf}, author = {J. G. Cepeda-Pizarro and Walter G. Whitford} } @mastersthesis {51611, title = {Diet botanical composition and fecal chemical indices of cows and steers on semidesert rangleland}, year = {1990}, note = {//??//NONE//}, month = {1990}, pages = {79}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle, diet, cattle,fecal chemical indices, dissertation, dissertations, theses, thesis}, author = {Ferrando, Carlos Alberto} } @article {51612, title = {Decomposition and soil nitrogen availability in Chihuahuan Desert field microcosms}, journal = {Soil Biology and Biochemistry}, volume = {22}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {241-249}, abstract = {

We examined the relationship between the decomposition of seven litter and root substrates, soil N availability, and populations of soil biota in field microcosm for 13 months. Most of the variation of N loss from the substrates was a function of initial substrate N concentration. Small portions of the variation of substrate mass loss and soil inorganic N were explained by initial substrate N concentration. Most of the variation of substrate mass losss, soil inorganic N, and soil biota populations was explained by differences between the decomposition of roots vs litter and of annual roots vs perennial roots. N loss from roots was more rapid than from litter. Mass of bacteria plus yeast in root microcosms was lower, nematode populations were higher, and the potential N mineralization rate at 9 months was higher than in litter microcosms. These results suggest that organic matter turnover in root microcosms was more rapid than in litter microcosms. Mass loss from annual roots was higher but N loss was lower than from perennial roots. Bacteria plus yeast mass in annual-root microcosms was lower, nematode populations were higher, and soil inorganic N was less than in perennial-root microcosms. The addition of annual roots reduced inorganic N concentrations below that of the unamended controls and the other substrate treatment on month 6 and 9 samples indicating that annual-root decomposition led to N immobiliaztion or dentrification. The addition of litter or perennial-roots increased soil inorganic N concentrations above the unamended control in the month 9 samples. The decomposition of N-poor annual plant roots may significantly reduce N availability in desert ecosystems.

}, keywords = {article, articles, decomposition, soil biota, journal, journals, soil bacteria, soil biota, soil microcosm, soil nitrogen, soil yeast, soil, litter decomposition, soil, nematode population, soil, root decomposition}, doi = {10.1016/0038-0717(90)90093-F}, url = {files/bibliography/JRN00118.pdf}, author = {F. M. Fisher and D. W. Freckman and Walter G. Whitford} } @article {51632, title = {Denitrification: enzyme content and activity in desert soils}, journal = {Soil Biology and Biochemistry}, volume = {23}, number = {9}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {845-855}, abstract = {

The content of denitrifying enzymes in upland desert soil was strongly associated with indices of N and C availability. Combinations of several predictors could explain 71\% of the variance in enzyme content in Chihuahuan desert soils and 87\% of the variance in soils from various deserts in the southwestern U.S.A. A significant fraction of the enzyme content in wet desert soil is derived form a persistent pool of enzymes capable of tolerating extended periods of desiccation. The synthesis of new denitrifying enzymes appears to involve a complex interaction between available C, N, and soil moisture. The activity of denitrifying enzymes in desert soil was optimal at a pH of 7.0 and a temperature of 40 C. The Q10 for denitrification was 1.74, and the activation energy was bout 41 kJ mol-1. In addition, enzyme activity in freshly wet soil was not limited by NO-3 availability, and only slightly limited by the availability of C. Thus, wet desert soil appears to provide optimal conditions for several variables that can influence denitrification.

}, keywords = {article, articles, denitrification, enzyme content, journal, journals, soil carbon, soil nitrogen, soil, denitrifying enzymes}, doi = {10.1016/0038-0717(91)90096-3}, url = {files/bibliography/JRN00120.pdf}, author = {Peterjohn, William T.} } @article {51634, title = {Distance traveled by free-ranging supplemented and nonsupplemented lactating and nonlactating cows}, journal = {Applied Animal Behavior Science}, volume = {28}, year = {1990}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1990. (http://www.sciencedirect.com/science/journal/01681591)}, month = {1990}, pages = {221-232}, abstract = {

Daily travel of protein supplemented and non-supplemented lactating and non-lactating mature (\>4 years of age) Santa Gertrudis X Hereford and Hereford X Santa Gertrudis crossbred cows was estimated between 29 May and 18 August 1986. The study was conducted on semidesert rangeland in south-central New Mexico. Ambient air temperatures ranged between 7 and 38{\textdegree}C. Relative humidity ranged between 15 and 91\%, with precipitation 49\% above the long-term January{\textendash}August mean of 147 mm. Four lactating and 4 non-lactating cows were fed an average of 1.4 kg per head day-1 of a 41\% crude protein cottonseed supplement every 3.5 days. Ten similar non-supplemented cows, 5 lactating and 5 non-lactating, were grazed with the supplemented animals in paddocks averaging \>2000 ha in size. To monitor travel, the 18 cows were each bi-pedometered with digital pedometers attached to their front legs.

}, doi = {10.1016/0168-1591(90)90101-I}, url = {/files/bibliography/358.pdf}, author = {R. R. Rouda and D.M. Anderson and L. W. Murray and J. N. Smith} } @article {JRN55152, title = {Decomposition along a rainfall gradient in the Judean desert, Israel}, journal = {Oecologia}, volume = {82}, year = {1990}, month = {March 1990}, pages = {322-324}, abstract = {

The effect of a rainfall gradient, from a semiarid to extremely arid, on decomposition, were studied in the Judean desert, Israel. During the study period, the rainfall gradient obtained ranged from 308 mm to 24.4 mm. There was a annual mass loss of approximately 20\% and 16\% in the semi-arid and extremely arid regions, respectively. No significant correlation was found between the total rainfall and total mass losses. The data suggest that in an area where the conditions are not suitable for biological activity, the decomposition processes result from abiotic conditions, like temperature and radiation.

}, keywords = {decomposition, desert, gradient, rainfall}, doi = {10.1007/BF00317478 }, url = {files/bibliography/90-Oecologia-Whitford.pdf}, author = {Yosef Steinberger and Avi Shmida and Walter G. Whitford} } @proceedings {51643, title = {Desert restoration: the role of woody legumes}, volume = {23-30}, year = {1990}, note = {//OTHER//LTER II//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: In}, month = {1990}, publisher = {Island Press}, abstract = {

Recent ecological studies of plant production, nutrient cycling, and water use by legume woodlands in the California Sonoran Desert and the Chihuahuan Desert of New Mexico have provided useful information for restoration efforts in these and in other arid and semiarid regions of the world. Where possible, nitrogen-fixing woody legumes should be included in desert revegetation programs since they enhance soil fertility. Understand and working to duplicate or mimic the natural patterns of moisture and nutrient availability found in these desert woodlands may improve the success rate for their revegetation.

}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, legume, desert restoration, proceeding, proceedings, restoration, legumes}, author = {R. A. Virginia}, editor = {Berger, J. J. (ed.)} } @mastersthesis {51680, title = {Differential biomass allocations of Gutierrezia sarothrae and Gutierrezia microcephala on a Chihuahuan Desert site}, year = {1989}, note = {//NMSU//NONE//}, month = {1989}, pages = {50}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Reproductive and vegetative biomass for Gutierrezia sarothrae and G. microcephala were measured along a transect on a Chihuahuan Desert site. The central portion of the transect contained an overlap zone where both species co-occurred. A single species zone existed at each end of the transect. Total biomass and reproductive allocation were calculated by species per zone to determine if lower overall biomass accumulation or increased reproductive allocation could be measured as a response to ecotone. It was found the Gutierrezia sarothrae did not show either lower overall biomass or increased reproductive allocation on the edge of its distribution. Gutierrezia microcephala did not show a lower overall biomass accumulation but did show an increased reproductive allocation response to the edge of its distribution.}, keywords = {biomass,Gutierrez, dissertation, dissertations, ecotone,Gutierrezia, Gutierrezia,biomass allocation, plant, Gutierrezia, biomass, plant, Gutierrezia, reproduction, theses, thesis, transect,Gutierrezia}, author = {Muldavin, Deborah} } @article {51695, title = {Determination of hydrologic parameters for selected soils in Arizona and New Mexico utilizing rainfall simulation}, year = {1989}, note = {//OTHER//NONE//}, month = {1989}, institution = {New Mexico Water Resources Research Institute}, address = {Las Cruces, New Mexico}, abstract = {This technical report contains the results from a study to determine hydrologic parameters for selected soils in Arizona and New Mexico. Data analyses indicate that the infiltration characteristics among the sites are quite similar. Differences can be attributed to the amount of organic ground cover on a plot, the antecedent water content of the soil prior to the experiment, and the surface roughness as measured with a point frame....}, keywords = {book, books, chapter, chapters, hydrology, processes, hydrology,infiltration, hydrology,model, hydrology,nutrients, hydrology,runoff plot, hydrology,sediment yield, model,hydrology, nutrient,runoff, rainfall simulation, report, reports, soil erosion}, isbn = {WRRI Report No. 243}, author = {Timothy J. Ward and Bolin, Susan B.} } @article {51725, title = {Depth distribution and seasonal populations of mesquite-nodulating rhizobia in warm desert ecosystems}, journal = {Soil Science Society of America Journal}, volume = {52}, number = {6}, year = {1988}, note = {//NMSU, USDA//LTER II//}, month = {1988}, pages = {1644-1650}, abstract = {

Deeply rooted woody legumes are common in desert ecosystems yet little is known about the distribution of their rhizobial symbionts in relation to their roots and soil properties of the systems. The distribution of mesquite (Prosopis glandulosa Torr.)- nodulating rhizobia was investigated to depths of 13 m in warm desert eco systems. Soils were collected under mesquite from sand dune and playa ecosystems in the California Sonoran Desert, and from sand dune, playa, arroyo, and grassland ecosystems in Ten Chihuahuan Desert of southern New Mexico. A Larrea tridentata (DC.) Coville (creosote bush) ecosystem in New Mexico, containing no mesquite, was sampled as a reference. Three intact soil cores from each ecosystem were removed during the winter, spring, and fall from the New Mexico sites, and the winter from the California sites. Significant rhizobial population densities were measured in soil from 1- to 4-m depths at the sand due, arroyo, and the playa ecosystems. Tat the playa ecosystem in New Mexico population densities \>105 cells kg-1 were measured in soils from 8-m depth, and root nodules containing rhizobia were recovered in soil samples from 3-, 4-, and 7-m depths. Multiple-regression analysis of rhizobial concentration against soil NH4-N, PO4-P, electrical conductivity, and gravimetric water content indicated that no single soil factor was related significantly to rhizobial concentration across the ecosystems. Rhizobial densities varied with season in the dune and arroyo ecosystems. In these desert ecosystems significant rhizobial populations, root nodules, and presumable symbiotic N2 fixation occur at soil depths rarely studied.

}, keywords = {article, articles, journal, journals, plant, Prosopis, Prosopis, nodulating rhizobia, rhizobia, Prosopis-nodulating}, doi = {10.2136/sssaj1988.03615995005200060026x}, url = {files/bibliography/JRN00073.pdf}, author = {Jenkins, Michael B. and R. A. Virginia and W. M. Jarrell} } @article {51735, title = {Distribution of annual plants in North American deserts}, journal = {Journal of Arid Environments}, volume = {15}, year = {1988}, note = {//NMSU//LTER I, US-IBP//}, month = {1988}, pages = {221-227}, abstract = {

Early researchers concluded that the winter-annual flora was richest in the California deserts and became relatively poorer towards the east, whereas summer-annuals were richest in the deserts of western Texas and their richness progressively declined in to eastern California. US/IBP Desert Biome and subsequent studies support these trends and add much relevant information. Winter-annuals have the C3 photosynthetic pathway, whereas most summer-annuals have the C4 pathway. While the Sonoran and Chihuahuan deserts have a few C3 {\textquoteright}summer{\textquoteright} annuals (actually {\textquoteright}winter{\textquoteright} annuals which can persist into the summer), the Mojave Desert lacks C3 summer-annuals. The Great Basin Desert has only a few prevalent winter or summer-annuals (mostly introduced species). Studies of the micro-distribution of desert-annuals have shown their close association with perennial shrubs. Some shrubs produce substances that are reportedly toxic to some annuals; the role of such toxins in structuring annual plant communities is unclear. The importance of nutrients associated with shrub canopies on the micro-distribution of many desert-annuals is becoming evident through LTER and other studies.

}, keywords = {annual plant, c3 and c4, annual plant, distribution, article, articles, journal, journals, plant, also SEE , plant, annual}, doi = {10.1016/S0140-1963(18)31059-0}, url = {files/bibliography/JRN00074.pdf}, author = {J. Ludwig and Gary L. Cunningham and P. D. Whitson} } @proceedings {51750, title = {Decomposition and nutrient cycling in disturbed arid ecosystems}, year = {1988}, note = {//NMSU//LTER I//ProCite field[6]: In}, month = {1988}, pages = {136-161}, publisher = {Westview Press}, abstract = {

Several studies focused on the effects of organic mulches of soil biota and soil processes in surface mined areas are reviewed. The effects of overgrazing and subsequent rangeland degradation on soil processes are described. Amending mine spoil materials with recalcitrant mulch materials, bark and wood chips, resulted in increased abundances and diversity of soil microflora and microfauna which resulted in decomposition rates similar to unmined soils. Other organic mulches, straw and sewage sludge, had short term or no effect on biota and decomposition. On surface mined areas reconstructed by contouring with a surface layer of topsoil amended with straw, the soil biota and processes were most similar to unmined soil the first year post restoration and diverged greatly by the fourth year. This restoration procedure failed to maintain a viable soil biota. Addition of organic amendments to intact but degraded rangeland had no long-term effect on soil processes, soil biota or vegetative production. In arid rangelands the shift in vegetation from grassland to shrubland has resulted in lowered nitrogen availability as evidenced by low total soil nitrogen and reduced nitrogen mineralization potential.

}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, decomposition, disturbed ecosystem,reclamation, mine reclamation, nitrogen mineralization, nutrient cycling, proceeding, proceedings, rangeland, surface mine reclamation, soil biota, soil restoration}, doi = {10.4324/9780429314216-7}, author = {Walter G. Whitford}, editor = {Allen, E. B. (ed.)} } @article {51749, title = {Decomposition of roots in a Chihuahuan Desert ecosystem}, journal = {Oecologia}, volume = {75}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {8-11}, abstract = {

Mass losses of tethered buried roots of two woody shrubs and two herbaceous annuals buried in plots irrigated at 25 mm/moth-1, 6 mm/week-1 and no irrigation were measured. At the end of 1 year, 10-15\% of the mass of the herbaceous annual roots remained and 60\% of the mass of woody shrub roots remained. There were no differences in mass loss attributable to added water. Rates of mass losses of roots in the Chihuahuan Desert were equal to or higher than those reported from mesic ecosystems. Roots of woody shrubs had relatively constant C:N ratios through the experiment. There was significant N immobilization in Baileya multiradiata roots. Percent mass loss of grass roots, Erioneuron pulchellum, and herbaceous annual roots, B. multiradiata, in plots without termites was 15\%. These data suggest that subterranean termites are responsible for most of the mass loss and mineralization of carbon and nitrogen in dead grass and herbaceous roots in the northern Chihuahuan Desert.

}, keywords = {article, articles, decomposition, roots, decomposition,roots, journal, journals, nitrogen immobilization, pesticide, Chlordane, rainfall simulation, decomposition, buried roots, root,decomposition, termite,decomposition}, doi = {10.1007/BF00378807}, url = {files/bibliography/JRN00072.pdf}, author = {Walter G. Whitford and Stinnett, K. and John P. Anderson} } @proceedings {51758, title = {Direct measures of the grazing animal{\textquoteright}s nutritional status}, year = {1987}, note = {Permission to post articles granted by the Society for Range Management; http://www.rangelands.org}, month = {1987}, pages = {40-57}, address = {Boise, ID}, abstract = {Accurate, precise, rapid and cost effective procedures must characterize the techniques used to measure an animal{\textquoteright}s nutritional status. The classical information on the grazing animal{\textquoteright}s nutritional status has been determined by monitoring the chemical composition of the standing crop, the botanical and chemical composition of diets using esophageally fistulated animals, and the use of physical measurements including liveweight. Tissue and body fluid analyses for the diagnosis of nutritional problems have been stimulated by the development of automated equipment. Techniques that use body condition scores, based on a visual appraisal or external palpation for subcutaneous fat, correlate well with stored energy in the animal. Body condition correlates with reproductive efficiency and milk production. Prepartum condition can be used to effectively manage fat and thin livestock according to their nutritional needs for optimum sustained production. To understand and accurately manage the complex relationships that exist at the plant-animal interface, no single measure will be adequate to describe {\textquoteright}the nutritional status of grazing animals. However, body condition scores should be considered as a cost- effective tool that can be used by both the producer and researcher.}, url = {/files/bibliography/305.pdf}, author = {D.M. Anderson} } @article {51775, title = {Diet and forage intake of cattle on desert grassland range}, journal = {Journal of Range Management}, volume = {40}, number = {4}, year = {1987}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {July 1, 1987}, pages = {339-342}, abstract = {

Cattle production on desert grassland ranges in southern New Mexico has been low, although limited research shows diet nutritional quality of cattle is adequate to meet production needs during most seasons. Forage intake data are lacking for cattle on desert grassland ranges. Five esophageal-fistulated steers were used to evaluate diet quality and botanical composition on desert grassland range in southern New Mexico. Another 6 steers were used to collect feces to determine intake. Cattle changed their diet with seasonal advance to maximize diet quality. Crude protein concentrations of cattle diets were well above those needed for lactation and daily gain during spring and summer. Diet samples were high in neutral detergent fiber (66-81\%), suggesting low energy in the forage. Low forage intake was the main nutritional constraint Identified. Even during the summer growing season, organic matter intake never exceeded 1.5\% of body weight. We speculate low intakes may have resulted from high summer temperatures that reduced grazing time. During the late fall and winter, low forage quality appears to explain suppressed Intake. Protein supplementation in late fall and winter, and energy supplementation in spring, should be advantageous. We caution that data on diet quality without information on forage intake may poorly describe nutritional status of range cattle.

}, keywords = {forages, nutrition, rangelands, ruminants}, doi = {10.2307/3898733 }, url = {/files/bibliography/315.pdf}, author = {M.D. Hakkila and Jerry L. Holechek and Wallace, J.D. and D.M. Anderson and Manual Cardenas} } @article {51788, title = {Diurnal activity patterns and vertical migration in desert soil microarthropods}, journal = {Pedobiologia}, volume = {30}, year = {1987}, note = {//NMSU//LTER I//}, month = {1987}, pages = {65-71}, abstract = {

The objectives of this research were to test the \"migration\" and \"cryptobiosis\" hypotheses and to examine the effect of increased soil moisture and reduced soil temperature on activity patterns of microarthropods in surface litter.... We concluded that the active resident population of soil microarthropods in surface litter accumulations in a desert is a function of time of day, which affects diurnal migrant species, and litter temperature, which affects activity of species that are capable of cryptobiosis. Physiological studies of species that appear capable of cryptobiosis are needed before we can assess the flexibility that this adaptation allows its possessor with respect to utilization of the rich energy and nutrient sources characteristic of leaf litter accumulations. This is especially important in deserts where soil organic matter is often less than 1\% by mass.

}, keywords = {Acarina, also SEE , article, articles, collembola, insect, Collembola, insect, Psocoptera, journal, journals, list,microarthropod, microarthropod, activity patterns, mite, activity patterns, mite, soil moisture, mite, surface litter, mite, temperature, mite, vertical migration, psocoptera, soil acari, cryptobiosis}, doi = {10.1016/0038-0717(81)90087-0}, url = {files/bibliography/JRN00053.pdf}, author = {William P. MacKay and Solange Silva and Walter G. Whitford} } @mastersthesis {51798, title = {Digestibility and intake of diets containing creosotebush by goats}, year = {1987}, note = {//??//NONE//}, month = {1987}, pages = {48}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, goat,diet, Larrea,goat diet, theses, thesis}, author = {Solis Ruiz, Ezequiel} } @proceedings {51817, title = {Designing and prototyping a scientific problem solving environment: the NMSU science workbench}, volume = {16}, year = {1986}, note = {//LOCAL//LTER//Listed in LTER2 proposal as citing LTER1 support//ProCite field[6]: In}, month = {1986}, pages = {383-409}, publisher = {The Belle W. Baruch Library in Marine Science}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, data management, proceeding, proceedings}, author = {W.H. Conley and Slator, B. and Martha Anderson and Sitze, R.}, editor = {Meiheuer, W. (ed.)} } @mastersthesis {51839, title = {Dietary botanical composition of goats grazing creosotebush-dominated rangeland}, year = {1986}, note = {//NMSU//NONE//}, month = {1986}, pages = {69}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Botanical composition of goats{\textquoteright} (Capra hircus) diets on creosotebush-dominated rangelands was evaluated by microhistological techniques. Four esophageal-fistulated goats were used to collect forage during five periods. A 2 x 3 x 5 factorial treatment design was utilized to evaluate stocking rates (2 goats/ha, 1 goat/ha and an ungrazed control pasture ) and breed of goat (Spanish vs Angora). Goat grazing was initiated August 1982 and continued until October 1983. Species selectivity by goats was determined by preference indices and was affected by species availability in many periods. There were no effects (P>.05) of breed on animal dietary selectivity. Grass, forbs, and shrubs comprised 37\%, 13\% and 45\%, respectively, of goats{\textquoteright} diets averaged over the study periods. Most abundant species in the diets were wolfberry (Lycium spp.), bush muhly (Muhlenbergia porteri), tarbush (Flourencia cernua) and fluffgrass (Erioneuron pulchellum). Goats were highly selective for plant species of low herbage biomass. Shrubs were used mostly in January, June and October while grass was utilized in March and September. Dietary shrub composition differed (P<.05) on the heavy stocking rate from that under the moderate and control treatments. Most forb species were only eaten during certain periods when they were more readily available.}, keywords = {Capra, diet, dissertation, dissertations, goat, Capra, goat, diet, goat, esophageal-fistulation, grazing, goat, Larrea, goat diet, mammal, goat, Capra, theses, thesis}, author = {Laribi, Mohamed Mouldi} } @book {51865, title = {Decomposition and nutrient cycling in deserts}, series = {Pattern and Process in Desert Ecosystems}, year = {1986}, note = {//NMSU//LTER I//ProCite field[6]: In}, month = {1986}, pages = {93-117}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {

The results of the recent International Biological Program and other studies suggest that nutrients, especially nitrogen, may limit productivity in desert ecosystems when moisture is available. Few studies examined decomposition processes in desert ecosystems prior to the initiation of our work, but here were fairly extensive efforts focused on nitrogen processes in desert ecosystems as part of the International Biological Program. In this review, I will address the problem of both decomposition and nutrient cycling processes in desert ecosystems and attempt, wherever possible, to demonstrate the relationships between these processes and primary productivity. Since these processes are mediated via the soil biota, I will emphasize soil biotic interactions and their importance, where these are known or suspected.

}, keywords = {book, books, chapter, chapters, decomposition, desertification, decomposition, desertification, mineralization, ecosystem, desertification, nutrient cycling, report, reports}, doi = { 10.1016/B978-012747261-4/50010-9}, url = {files/bibliography/86-EclgyOfDsrtSystm-Whitford.pdf}, author = {Walter G. Whitford}, editor = {Walter G. Whitford} } @mastersthesis {51868, title = {Development and production of bush muhly (Muhlenbergia porteri (Scribn.) ex Beal.) and sand dropseed (Sporobolus cryptandrus (Torr.) Gray) following herbicidal control of mesquite}, year = {1986}, note = {//NMSU//NONE//}, month = {1986}, pages = {68}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Herbicidal treatment of mesquite is one of the many ways of controlling this shrubby species. Dense mesquite stands impair grass production in many areas of southwestern United States. Grass recovery is related to the structural characteristics of the plant which often differs among species. The objectives of this study were to describe the structural changes in basal circumference, crown diameter, height, stem number, internode number, branch number and phenology of bush muhly (Muhlenbergia porteri [Scribn.] ex Beal.) and sand dropseed (Sporobolus cryptandrus [Torr.] Gray.) in a sprayed and non-sprayed mesquite community; determine the growth of the two species as influenced by mesquite canopy and to relate different plant attributes measured to standing dry weight and determine how the herbicide treatment and the mesquite canopy affect soil water at three soil depths. The study was conducted at the New Mexico State University College Ranch, located approximately 32 km north of Las Cruces in Dona Ana County, New Mexico.}, keywords = {brush control,Prosopis, community, Prosopis, dissertation, dissertations, grass, bush muhly,Muhlenbergia, grass, sand dropseed,Sporobolus, herbicide,Prosopis, Muhlenbergia,phenology, productivity, Muhlenbergia, productivity, Sporobolus, Prosopis,herbicide, Sporobolus,phenology, theses, thesis}, author = {Amade Younga} } @proceedings {51893, title = {The detrital food web and surface mine reclamation}, year = {1985}, note = {//OTHER//NONE//ProCite field[6]: In}, month = {October 8-10, 19}, address = {Denver, Colorado}, abstract = {Soil microorganisms and microfauna are major constituents of the detrital food web. As they decompose plant and animal residues they recycle essential plant nutrients. In so doing they regulate the productivity of the system. Because of their major role in system regulation this presentation will investigate the processes involved in the development of a detrital food web in disturbed mine spoils.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, decomposition, mine spoils, food web, detrital, mine spoils,decomposition, proceeding, proceedings}, author = {L. W. Parker and Walter G. Whitford} } @article {51898, title = {Distribution and diversity patterns of soil mites and other microarthropods in a Chihuahuan Desert site}, journal = {Journal of Arid Environments}, volume = {9}, year = {1985}, note = {//NMSU//LTER I//}, month = {1985}, pages = {215-231}, abstract = {

Mites were more abundant than Collembola in all sites except in Prosopis litter from the edge of a playa. At this site, collembolan density was estimated to be 24 460/m2. Four orders of mites occurred in the sites surveyed: Prostigmata, Cryptostigmata, Mesostigmata and (infrequently) Astigmata. Mesostigmata were numerous only in Atriplex litter. Prostigmata and Cryptostigmata were equally abundant only in the litter under Prosopis and on the bajada site and mineral soil under Fallugia. Elsewhere, Cryptostigmata tended to be more numerous than Prostigmata where the organic content of the substratum was high (\>30\%) and vice versa. The highest total mite density occurred in the Juniperus litter (29 486/m2), the lowest in Larrea litter (8274/m2). An Index of Diversity, calculated for the various groups of microarthropods at the 12 sites, was very variable. The equitability component of this species diversity provided a good indicator of the relative stability of the sites studied.

}, keywords = {collembola, distribution patterns, diversity patterns, invertebrate, journals, mite, soil}, author = {J. A. Wallwork and B. W. Kamill and Walter G. Whitford} } @proceedings {51899, title = {The dynamics of liveweight in cattle grazing southwestern United States semiarid rangeland}, year = {1984}, month = {May 13, 1984}, pages = {402-403}, address = {Adelaide, Australia}, abstract = {This paper alleges that information necessary to make management decisions, such as calving date, and improved precision in estimating characteristics of an individual cow{\textquoteright}s liveweight profile can be obtained when liveweights taken frequently and automatically are compared to liveweights taken at greater than 27-day intervals using conventional methods. The measurement, liveweight, is used to evaluate biological and economic components of production animal agriculture. Changes in liveweight are dynamic, both diurnally and seasonally, mainly in response to body fluids anti fill (Anderson and Tietjen, 1982). To reduce variability in the mean liveweight between animals, past research has been directed to evaluate number of animals to be weighed, time of weighing, type and length of fasting, and the use of consecutive weighings (Hughes, 1976). Until the advent of single animal electronic scales and individual electronic animal identification, frequent weighing of free ranging cattle was not practical (Anderson, Landt and Salazar, 1981). Automatic liveweight data acquisition reduces the incidence of transcriptional and phonetic errors and variability in data taken during manual weighing arising from nervous animalsthat move excessively on the scale platform. Analyses in this paper compare liveweight data of free ranging cattle obtained when both infrequent manual and automatic weighings were recorded. Prior to drinking, automatically obtained individual liveweights were taken whenever animals entered the corral to drink water.}, keywords = {cattle, grazing, liveweight, management, semiarid rangeland}, url = {/files/bibliography/286.pdf}, author = {D.M. Anderson and Weeks, D.L.} } @conference {51906, title = {Demographic sensitivity of two perennial grasses in arid grassland}, booktitle = {37th Annual Meeting, Society for Range Management}, year = {1984}, month = {1984}, pages = {No. 266}, keywords = {arid grassland, demographic sensitivity, perennial grasses}, author = {Gross, B.D. and Gibbens, Robert P.} } @article {51900, title = {Development of the Polypay breed of sheep}, journal = {Journal of Animal Science}, volume = {58}, number = {1}, year = {1984}, month = {1984}, pages = {15-24}, abstract = {

Achievement of improved reproductive performance in most domestic sheep breeds of the United States has been regarded with considerablecaution because of low heritabilities for reproductive traits. However, this view is changing with increasing availability of exotic breeds that have high reproductive capacity. The characterization of these exotic breeds in crosses with domestic breeds has shown that major improvement in reproductive rate is attainable. Crossbreeding has been demonstrated to be an effective method for exploiting the commercial value of highly prolific breeds (Turner, 1969; Carter, 1976; Dickerson, 1977; Jakubec, 1977; Meyer et al., 1977). The development of composite breeds that combine the potential for greatly increased reproductive rate along with the desired growth, carcass and fleece attributes is an important extension from crossbreeding for achieving important and permanent increases in production efficiency (Carter, 1976; Smith et al., 1979; Hulet et al.,1981).

}, url = {/files/bibliography/267.pdf}, author = {Clarence V. Hulet and Ercanbrack, S.K. and A. D. Knight} } @proceedings {51931, title = {Diets obtained from esophageally fistulated heifers and steers simultaneously grazing semidesert tobosa rangeland}, volume = {34}, year = {1983}, month = {1983}, pages = {161-164}, abstract = {

The espohageally fistulated animal is a well recognized and accepeted range nutrition research tool. Esophageally fistulated animal studies have been conducted to evaluate diet differences between kinds and breed of animals, various grazing management strategies, different seasons of use, geographic locations, and diurnal diet patters. This study was conducted to determine how diet samples taken from one class of animals compare to diet samples taken from another class of animal within the same species. Cattle of mixed Bos taurus breeding prepresented by four esophageally fistulated mature steers and five esophageally fistulated growing heifers were used. the two groups were allowed to simultaneously graze tobosa (Hilaria mutica rangleland daily for a period of approximately 30 minutes between June 19 and June 29, 1979. The diet chemical components, crude protein and in vitro organic matter were analyzed. Analysis of the botanical components of the deit indicated five grasses thriteen forbs and three shrubs. This diversity in botanical composition contributed to a diet which had a mean grass, forb, and shrub content of 35, 51 and 14\%, respectively. Analysis of the dependent variables indicated that deits between the animal higher (p\<.10) in crute protein and three forb components. Heifer deits were 2.4\% higher (P\<.05) in crude protein compared to the steer diets. These results indicated caution should be used when extrapolating diet data collected from one class of animal to anohter class of animal within the same species. In addition to sex sex differences tarbush (Flourensia cernua), considered an invader shrub species, contrubuted to 92\% fo g of the diets in which botanical components were analyzed.

}, url = {/files/bibliography/227.pdf}, author = {D.M. Anderson and Jerry L. Holechek} } @inbook {51954, title = {Development of the Polypay breed of sheep}, booktitle = {Sheep and Goat Handbook}, year = {1983}, month = {1983}, pages = {137-151}, publisher = {Winrock International, Westview Press}, organization = {Winrock International, Westview Press}, address = {Boulder, CO}, abstract = {

Development of the Polypay breed was undertaken to combine into a composite breed the potential for greatly increased reproductive capacity along with desirable growth rate and carcass quality. Four breeds were selected for the foundation of the new breed-the Rambouillet and the Targhee for hardiness, large body size, long breeding season, herding instinct and fleece characteristics; the Dorset for carcass quality, milking ability and long breeding season and the Finnsheep for early puberty, early postpartum fertility and high lambing rate. Dorset x Targhee and Finnsheep x Rambouillet matings were first made in 1968, and reciprocal Dorset-Targhee x Finn-Rambouillet matings were initiated in 1969. Beginning in 1970, the respective two-breed crosses and the four-breed cross (Polypay) were each mated inter se and selected, along with straight bred Rambouillets and Targhees, or lamb production when given two opportunities to lamb/year. Initial comparisons among straightbreds and inter se mated groups showed few important differences in meat-type body conformation, body condition or growth rate, but superior annual reproductive performance by Polypays. Fertility of Polypays at 1 yr of age was high and comparable to that of the Finn- Rambouillets. Response of Polypays to twice-a-year lambing was superior to responses of Rambouillets, Targhees, Dorset-Targhees or Finn-Rambouillets. The 1974 to 1975 annual production of young Polypays was about 13\% more lambs weaned than from Finn-Rambouilets and 18\% more weight of lamb weaned than from Dorset-Targhees, the best of the other groups for these traits. The current (1979 to 1981) reproductive performance of Polypay ewes selected for high once-a-year lambing rate under typical range management conditions is very competitive with that of 89 Finn cross- breds. Annual production of mature Polypays on the twice-a-year lambing schedule was 1.78 lambs weaned and 58.6 kg of lamb weaned/ewe put into fall breeding.

}, keywords = {Composite Breed Development, Polypay, Reproductive Performance, Selection}, url = {https://pdfs.semanticscholar.org/dae2/6928c6101933dc0b1bc6a0dc17684083152c.pdf}, author = {Clarence V. Hulet and Ercanbrack, S.K. and A. D. Knight}, editor = {Baker, F.H.} } @article {51980, title = {Decomposition rates of various quantities of buried litter in a desert}, journal = {The Southwestern Naturalist}, volume = {28}, year = {1983}, note = {//NMSU//NONE, LTER//}, month = {1983}, pages = {111-112}, abstract = {

Creosobebush (Larrea tridentata) fine litter was treated with either the general biocide HgCl2 and CuSO4 or water (controls) and buried 5 cm beneath the soil surface in the northern Chihuahuan Desert. The treated litter showed significantly less mass loss than controls during the three month summer-autumn field study; controls lost about 20\% of the original mass while treated litter lost less than 2\%. In addition, the total nitrogen content of the control litter increased from an initial concentration of about 14.08 g kg-1 to 17.62 g kg-1 dry weight by the end of the study, while treated litter nitrogen content decreased to 13.30 g kg-1. Results suggest abiotic processes other than leaching have little effect on the decomposition of buried litter in this environment.

}, keywords = {article, articles, decomposition, buried litter, decomposition,litter,Larrea, journal, journals, Larrea, decomposition, litter,Larrea decomposition}, url = {files/bibliography/JRN00006_0.pdf}, author = {Urbaniak, Sandra and Walter G. Whitford} } @proceedings {51988, title = {Developing grazing strategies on arid and semiarid rangelands}, year = {1982}, month = {1982}, pages = {124-133}, address = {College Station, TX}, abstract = {Livestock operators have always sought ways to improve their returns from the land. At first glance, the situation appears relatively simple: we wish to graze ranges to optimize livestock production and yet maintain the range in a highly productive state. However, the problem becomes extremely complex when one considers the wide range of climatic and managerial conditions across the rangelands of the world. Use of specialized grazing systems has been one method to increase rangeland productivity. Although intensive research into grazing schemes is fairly recent, specialized grazing methods have been utilized for many years (Hickey, 1966; Davies, 1976; Voisin, 1959). Many of these methods were developed for use on improved pastures under relatively high precipitation but principles may apply to rangelands. Most schemes on arid and semiarid rangelands have been relatively simple. Interest in specialized grazing systems in the U.S. has peaked and then waned during the last 100 years. During the late part of the 19th and the early part of the present century, early range workers such as J. G. Smith, J. L. Jardine and A. W. Sampson advocated some type of rotational grazing to promote range improvement. Sampson (1913) initiated studies on rotational grazing in the Wallowa Mountains of Oregon. After World War II, interest in grazing systems was renewed by work of Hormay (1961) in California and Merrill (1954) in Texas. Two symposia on grazing systems were sponsored by the Society for Range Management (Sampson, 1951; Heady, 1969). However, adoption of specialized grazing systems by private ranchers has been slow. Success stories such as the one portrayed by Leo Merrill at Sonora did not persuade ranchers to develop such systems. Recently, however, a range ecologist from Zimbabwe has again kindled interest in a method of grazing in which intensive management provides the opportunity for high flexibility when grazing livestock. Private ranchers, as well as those grazing under permit on public ranges, have become interested in short duration grazing, more recently termed the Savory Grazing Method, in spite of relatively high initial investment costs. Since little detailed information is available on short duration grazing in North America, several universities and research stations have undertaken research to test certain hypotheses about short duration grazing. The purpose of this paper is to review some of the considerations and expectations for initiating specialized grazing strategies.}, keywords = {arid rangelands, grazing strategies, grazing systems, review, semiarid rangelands}, url = {/files/bibliography/210.pdf}, author = {Allison, C.D. and D.M. Anderson and Reldon F. Beck and G.B. Donart and Pieper, Rex D. and Schickedanz, J.G.} } @proceedings {51990, title = {Drylot shrink of cattle grazing semidesert rangeland during February, May, July and October}, volume = {33}, year = {1982}, month = {July 7-9, 1982}, pages = {242-245}, abstract = {Selling cattle by liveweight is the preferred method for economic remuneration (Ares, 1942; Hall, 1977). As a research tool, liveweight is used extensively by scientists to describe treatment effects (Morris, 1967). Bone, tissue, pelage, various fluids and digestive tract contents (fill) combine to give liveweight. Even though bone, tissue and pelage vary between animals (Andersson et al., 1979; Murray, 1980), fill and fluids are the most variable components. Fill and fluids can change diurnally in response to forage quantity (Currie, 1975), forage quality (Ward, 1975), physiological status (Allen, 1946), handling method (Brownson, 1973), animal behavior (Arnold and Dudzinski, 1978) and weather (Fuquay, 1981), besides the interaction of one or more of these factors operating simultaneously (Hughes, 1976). There is not unanimous agreement on the best method to reduce variability in liveweight between animals due to differences in fill and fluids. Matches (1981) advocates a dry lot shrink when liveweights are used to evaluate short-term grazing experiments. Harris et al. (1967) on the other hand, indicate that gathering animals prior to morning grazing followed immediately by weighing will give precise liveweights. Time of day when weighing is done is important if variability in fill and fluids is to be kept to a minimum. Water intake for example can occur any time during a 24-hour period as documented by Low et al. (1981). This study was conducted to evaluate the liveweight profile resulting from a drylot shrink of cattle grazing semiarid rangeland during February, May, July and October.}, keywords = {cattle, drylot shrink, liveweight profile, semidesert rangeland}, url = {/files/bibliography/214.pdf}, author = {D.M. Anderson and Tietjen, G.} } @proceedings {52042, title = {Drought and grazing management decisions}, year = {1981}, month = {1981}, pages = {187-192}, publisher = {Texas Agriculture Extension Service}, address = {Del Rio, TX}, abstract = {

Drought is unique among spells of weather; it creeps upon us gradually, almost mysteriously, but its consequences are a terrible reality. In many instances the damaging effects of drought on the vegetation are not fully realized until it is over. The semiarid and arid lands which make up the greater part of the grazing areas of the world are subjected to protracted periods of deficient precipitation and hence decreased production of forage. It is a common practice for grazing lands to be fully stocked on the basis of the average or better season before a drought. Consequently, if grazing is not immediately reduced in proportion to the decline in forage production, there will be heavy overgrazing with subsequent injury to the forage species. The deterioration of many grazing lands began during protracted drought periods. There generally is no problem in managing the range resource during the wetter years. The years of less than average precipitation set the pattern of land use, and must be anticipated and planned for safe utilization of the range.

}, url = {/files/bibliography/201.pdf}, author = {C.H. Herbel and Gibbens, Robert P.} } @article {52063, title = {Diurnal migration and responses to simulated rainfall in desert soil microarthropods and nematodes}, journal = {Soil Biology and Biochemistry}, volume = {13}, year = {1981}, note = {//LOCAL//NONE//}, month = {1981}, pages = {417-425}, abstract = {

Diurnal patterns of microarthropod abundance in surface leaf litter were related to its moisture content. Leaf litter moisture was nearly 7\% by weight at 0800 h but fell to less than 1 \% by mid-day. Oribatid and tydeid mites moved into litter in the early morning and back into the soil before mid-day. There were no significant differences in numbers of nematodes in litter or soil and 78098\% of the nematodes were anhydrobiotic (coiled) in soil and litter at all times sampled. Following simulated rainfall there were fewer microarthropods in litter at mid-day in the absence of marked decreases in soil and litter moisture content. During drying, there were gradual reductions in numbers and species diversity of litter microarthropods. Nematode numbers did not change as litter dried. Anhydrobiotic nematodes in the soil increased from 14\% on day 1 to 85\% on day 4. Between 24 and 36 h after simulated rainfall, the proportion of anhydrobiotic litter nematodes increased from 35 to 80\%. Within 1 h after simulated rainfall, there were marked increases in numbers and diversity of microarthropods in surface litter. No collembolans were extracted from dry litter controls but the wet litter was dominated by isotomid, sminthurid and onychiurid collembolans. There were increases in numbers and diversity of oribatid, tydeid and gamasid mites in the wet surface litter within 1 h after wetting compared to controls.

}, keywords = {article, articles, journal, journals, microarthropod,diurnal migration, microarthropod,simulated rainfall, nematode,diurnal migration, nematode,rainfall simulation, rainfall simulation}, doi = {10.1016/0038-0717(81)90087-0}, url = {files/bibliography/81-SoilBioandBioChem-Whitford.pdf}, author = {Walter G. Whitford and D. W. Freckman and Ned Z. Elkins and L. W. Parker and Parmalee, Rob and Janice Phillips and Tucker, Suzanne} } @mastersthesis {52116, title = {Diversity and density of ants on herbicide treated rangelands}, year = {1980}, note = {//USDA//NONE//}, month = {1980}, pages = {55}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Ant species diversity and colony density were studied on desert-grassland habitats sprayed with 2,4,5-T for mesquite (Prosopis glandulosa) control.... Nest densities were highest on the two untreated sites, but diversity and richness were greater on the herbicide-treated sites. These differences in ant populations probably developed as food resources, interspecific competition and favorable nest sites changed following habitat perturbation. Omnivorous ants were dominant on all sites, but their diversity was higher on sites where Conomyrms spp. were reduced. Seed harvesting ants were most dense on sites where perennial grass cover was high and soils were stable. Ants adapted to a liquid diet (honey-dew) were not affected adversely by the vegetation changes on sprayed sites. Densities of fungus-growing ant colonies were significantly higher on the two herbicide-treated sites. These higher densities may be due to the synchronization of nuptial flights of the ants and the mesquite leaf fall which aided in the successful establishment of new colonies by queens who had access to a food source unavailable to queens on areas not treated with herbicide.}, keywords = {ant, diversity, ant, herbicide, ant,density, arthropod, also SEE , brush control, herbicide, dissertation, dissertations, herbicide,rangeland, theses, thesis}, author = {Wendy Wisdom} } @proceedings {52134, title = {Dried irradiated sewage solids as supplemental feed for cattle}, year = {1979}, month = {1979}, author = {Geoffrey Smith and H.E. Kiesling and Ray, E.E. and Orcasberro, R. and Trujillo, P.A. and C.H. Herbel and Sivinski, J. S.} } @article {52165, title = {The distribution and phytosociology of Yucca elata in southern New Mexico}, journal = {The American Midland Naturalist}, volume = {100}, number = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {202-212}, abstract = {

The ecological distribution and phytosociological characteristics, i.e., species correlations and associations and spatial patterning, of Yucca elata were examined on the New Mexico State University Jornada Ranch. Yucca elata has a similar geographical and edaphic distribution on the Jornada as in the Chihuahuan Desert as a whole. Yucca elata is significantly associated with Prosopis glandulosa and Xanthocephalum sarothrae around a playa site on the Jornada Ranch. However, a general lack of significant correlations and associations between Y. elata and other species in desert scrub and grassland communities indicates the ubiquitous nature of this species. It reaches its best development in the desert grassland community and occurs in the more mesic areas of the desert scrub communities, possibly being a relic of past grassland vegetation in these areas. Individual canopies exhibit strong clumping due to vegetative propagation being the dominant form of reproduction. Cattle and fire disturbance appear to increase clumping in the species.

}, keywords = {article, articles, journal, journals, Yucca,distribution, Yucca,phytosociology}, doi = {10.2307/2424790 }, url = {/files/bibliography/309.pdf}, author = {Stanley D. Smith and J. Ludwig} } @article {52181, title = {Distribution and trophic structure of nematodes in desert soils}, journal = {Ecological Bulletin (Stockholm)}, volume = {25}, year = {1977}, note = {//??//??//}, month = {1977}, pages = {511-574}, keywords = {article, articles, journal, journals, nematode,distribution, nematode,trophic structure}, author = {D. W. Freckman and Mankau, R.} } @proceedings {52188, title = {Distributional adaptations of root systems in desert environments}, volume = {Range Science Dept. No. 26}, year = {1977}, note = {//NMSU//US-IBP//ProCite field[6]: In}, month = {1977}, pages = {85-90}, publisher = {Colorado State University}, edition = {No. 26}, abstract = {Early studies on the distribution patterns of root systems of desert plants are reexamined in view of recent IBP studies. Unpublished studies on root habits of desert plants in North America are used along with studies from other deserts of the world to support conclusions. Desert shrub species with the broadest local and geographical distribution have a generalized type of root system, where a tap root and lateral roots are both capable of extensive horizontal and vertical distribution. This appears to be an adaptation where these species can establish on the highly varied desert soils. However, this distribution adaptation is probably not unique to desert shrubs and thus is not a special adaptive mechanism for drought resistance. Other anatomical, morphological, and physiological adaptations exhibited by desert shrubs are probably of greater importance to their establishment and long-term survival.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, proceeding, proceedings, root systems, shrub, root system, shrub, root:shoot ratios}, author = {J. Ludwig}, editor = {J. K. Marshall (ed.)} } @mastersthesis {52195, title = {The development and use of a mathematical model to describe the effects of leaf angle and shading on the net CO2 exchange of Perezia nana}, year = {1977}, note = {//??//NONE//}, month = {1977}, pages = {72}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, keywords = {carbon dioxide,Perezia, dissertation, dissertations, model,CO2 exchange, model,leaf angle \& shading, Perezia,CO2 exchange, photosynthesis,Perezia, physiology,Perezia, theses, thesis}, author = {J. P. Syvertsen} } @article {52211, title = {Dynamics of bird communities in the Chihuahuan Desert, New Mexico}, journal = {The Condor}, volume = {78}, number = {4}, year = {1976}, note = {//NMSU, USDA//US-IBP//}, month = {1976}, pages = {427-442}, abstract = {

The initiation in 1971 of regular, year-round bird censuses and reproductive studies on three sites of the Analysis of Ecosystems, U. S. International Biological Program (IBP) provided the means and incentive to overcome the disadvantages of studying temporal changes as just outlined.... The data thus provide a basis for discussion of both within- and between-community variation in a number of community characteristics. In this paper we will stress overall levels of numbers and biomass, temporal changes in them, and the factors that might be responsible for them.

}, keywords = {article, articles, bird community, climate, bird community,food supply, journal, journals, list,birds}, url = {/files/bibliography/218.pdf}, author = {Ralph J. Raitt and Stuart L. Pimm} } @mastersthesis {52242, title = {Developmental morphology of the vegetative shoots of two cultivars of Bouteloua gracilis (H.B.K.) Lag ex Steud. in relation to clipping}, year = {1975}, note = {//??//NONE//}, month = {1975}, pages = {59}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {Bouteloua,morphology, dissertation, dissertations, grass,Bouteloua, theses, thesis}, author = {de Luna-Villarreal, R. R.} } @proceedings {52232, title = {The desert soil-geomorphology project}, volume = {26th Field Conference}, year = {1975}, note = {//LOCAL//NONE//}, month = {1975}, pages = {183-185}, publisher = {New Mexico Bureau of Mines and Mineral Resources}, abstract = {The Desert Soil-Geomorphology Project refers to a Soil Conservation Service, USDA, investigation between 1957 and 1972, of landscape evolution and soil development in a 400 sq mi area of Dona Ana County, New Mexico (Fig. 1). Its primary purpose was to gather basic information on soil-geomorphic relationships that would lead to increased accuracy and efficiency of the Soil Survey program in arid and semi-arid regions of the western states. A team of soil scientists and geologists from the S.C.S. Soil Survey Investigations Division under the direction of Guy D. Smith staffed the project.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, Desert Project,publication list, geomorphology, landscape, evolution, list,Desert Project publications, proceeding, proceedings, soil, development, soil-geomorphic relationships}, author = {J. Hawley} } @mastersthesis {52244, title = {The distribution and productivity of Flourensia cernua D.C. (tarbush) in southern New Mexico}, year = {1975}, note = {//LOCAL//NONE//}, month = {1975}, pages = {74}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The absolute cover and productivity pre new growth shoot of Flourensia cernua D.C. were looked at with respect to 16 selected soil variables and xylem sap potential along a 1400 m belt transect traversing 5 different plant communities near an enclosed basin in southern New Mexico.... Productivity per new growth shoot, xylem sap potentials, and soil water potentials were observed to be their highest in a Hilaria community with the lowest absolute cover value of Flourensia. The low absolute cover of Flourensia in this community was attributed primarily to the large absolute cover of Hilaria for it had been found by others that Flourensia will increase in disturbed Hilaria communities.}, keywords = {dissertation, dissertations, Flourensia, distribution, Flourensia, plant cover, Flourensia, productivity, productivity,Flourensia, soil, Flourensia, theses, thesis}, author = {T. O{\textquoteright}Laughlin} } @article {52277, title = {Dispersal and host location of the horn fly}, journal = {Environmental Entomology}, volume = {3}, number = {1}, year = {1974}, note = {//NMSU, USDA//NONE//}, month = {1974}, pages = {107-111}, abstract = {Horn fly host location in relation to various environmental factors was investigated. There were no significant differences between the success of newly emerged horn flies and day-old flies in locating hosts, or between males and females of either age. In a variety of weather conditions, horn fly dispersal and subsequent host location appeared to be random with respect to predominant wind direction. Directional movements, however, were influenced by temperature, wind velocity, and humidity. The temperature threshold for host location was cs. 18.3 degrees Celsius, and successful location increased as temperature increased from that level. Host location was more successful at low wind velocities; very few flies successfully located a host at high (10-20 mph) wind velocities. Increased wind velocity was the most important adverse factor affecting upwind orientation, while higher humidity levels appeared to assist host location on the upwind positions. High air temperature was the most important factor aiding host location on animals downwind and crosswind to fly-release points. Higher humidity and wind velocity contributed to lower levels of host location in downwind positions. Flies released in evening (2130 h) and early morning (0330 h) were more successful in host location than those released in daylight hours, i.e., 0930 and 1530 h. Horn flies were able to fly 7.3 miles in a 10-h period to locate a bovine host. There was a strong tendency for both parous and nulliparous flies to transfer from one host to another.}, keywords = {article, articles, cattle, horn fly, horn fly, insect, horn fly, journal, journals, parasite, horn fly}, author = {Kinzer, H. G. and Reeves, J. M.} } @article {52286, title = {Decomposition carbon and nitrogen changes}, year = {1974}, note = {//??//US-IBP//}, month = {1974}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {book, books, carbon,decomposition, chapter, chapters, decomposition,carbon, decomposition,nitrogen, nitrogen,decomposition, report, reports}, isbn = {Research Memorandum 74-38}, author = {E.E. Staffeldt and Besmond, K.} } @mastersthesis {52291, title = {Distribution and ecology of two pocket gopher species in south central New Mexico}, year = {1973}, note = {//??//??//}, month = {1973}, school = {New Mexico State University}, type = {M.S. Thesis}, address = {Las Cruces, New Mexico}, keywords = {dissertation, dissertations, mammal, SEE , rodent,distribution, rodent,ecology, rodent,pocket gopher, theses, thesis}, author = {M. S. Alberico} } @conference {52330, title = {A demographic study of some semidesert grassland plants}, booktitle = {25th Annual Meeting, Society for Range Management}, year = {1972}, month = {1972}, pages = {7-8}, keywords = {demographic study, semidesert grassland plants}, author = {P.L. Dittberner and C.H. Herbel} } @article {52338, title = {Drought effects on a semidesert grassland range}, journal = {Ecology}, volume = {3}, year = {1972}, month = {1972}, pages = {1084-1093}, abstract = {A vegetational survey on the Jornada Experimental Range in southern New Mexico, taken annually from 1941 through 1957, is the basis for a study of the effects of the great drought of 1951 through 1956. Both cover and yields were studied. Observations were stratified into seven classes based on a consideration of landform and soil characteristics. Seasonal and annual precipitation during the drought averaged 55\% of the pre-drought average. The most severe drought years were 1951, 1953 and 1956. Both the cover and yield of Bouteloua eriopoda (Torr.) Torr., the dominant species on the upland sandy soils, were greatly reduced by drought. However, drought damage was much more severe on the deep than on shallow sands. When the impermeable caliche layer occurred at shallow depths, moisture relations during drought were apparently much better than when caliche occurred at greater depths. Another result of drought was the invasion of Prosopis juliflora (Sw.) DC. in areas where grass stands have been thinned by drought. Sporobolus spp. and Aristida spp., minor components of the climax, were more susceptible to drought damage than Bouteloua eriopoda. Yields of perennial grasses per unit cover were as great during the drought as prior to the drought. Both winterspring and summer precipitation are important in preventing death losses of black grama. In arid areas, it seems necessary to consider both cover and species composition in arriving at a potential for a site.}, keywords = {cover composition, drought effects, semidesert range, species composition}, url = {/files/bibliography/135.pdf}, author = {C.H. Herbel and F.N. Ares and Robert Anderson Wright} } @article {52340, title = {Distribution and balance of biomass and nutrients in a desert shrub ecosystem}, year = {1972}, note = {//??//US-IBP//}, month = {1972-73-74}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {biomass,distribution, book, books, chapter, chapters, nutrient,distribution, report, reports, shrub ecosystem,biomass distribution, shrub ecosystem,nutrient distribution}, isbn = {Research Memorandum 72-14, 73-8, 74-6}, author = {Klemmedson, J. O. and Barth, R.} } @article {52351, title = {Demography and role of herbivorous ants in a desert ecosystem as functions of vegetation, soil and climate variables}, year = {1972}, note = {//??//US-IBP//}, month = {1972}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant,demography, ant,herbivorous, book, books, chapter, chapters, demography,ants, herbivory,ants, report, reports}, isbn = {Research Memorandum 72-32}, author = {Walter G. Whitford and George Ettershank} } @mastersthesis {52353, title = {A demographic study of a semidesert grassland}, year = {1972}, note = {//??//NONE//}, month = {1972}, pages = {221}, school = {Colorado State University}, type = {Ph.D. Dissertationpp}, address = {Ft. Collins, Colorado}, keywords = {demography, plant, dissertation, dissertations, grasslands, plant demography, plant demography, chart quadrat maps, technique, chart quadrat maps, theses, thesis}, author = {R. G. Wright} } @mastersthesis {52355, title = {The distribution of shrubs along a soil water potential gradient in a desert arroyo system}, year = {1971}, note = {//??//NONE//}, month = {1971}, pages = {21}, school = {New Mexico State University}, type = {M.S Thesispp}, address = {Las Cruces, New Mexico}, abstract = {The soil water potential gradient was ascertained by placing 12 gypsum electrical resistance soil moisture blocks at 12 locations along an arroyo. The electrical resistances of the block were measured at weekly intervals during the growing season. The soil water potential values were integrated over the 26 week-period for each of the 12 locations. The results were values indicative of the total soil moisture stress the plants were subjected to during their growing period. A general integrated soil water potential curve was calculated by regressing these values onto distance down the arroyo....The results showed that the vegetation was responding not only to the soil water potential gradient, but also to the effects of interference from other species. Three types of response patterns were seen.}, keywords = {arroyo,shrub distribution, dissertation, dissertations, shrub, arroyo distribution, theses, thesis}, author = {F. R. Balding} } @mastersthesis {52358, title = {A demographic study of some semidesert grassland plants}, year = {1971}, note = {//USDA//NONE//}, month = {1971}, pages = {81}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {This study determined the lifespans of some of the more important species of semidesert grassland plants and investigated the use of life tables in the evaluation of plant demographic studies.}, keywords = {demography, grassland plants, dissertation, dissertations, grassland, plant demography, plant, demography, theses, thesis}, author = {P.L. Dittberner} } @proceedings {52373, title = {Decomposer and nutrient cycling investigations in the Grassland Biome}, year = {1971}, note = {//USDA//US-IBP//NMSU library QH541.5 .P7 .P74//ProCite field[6]: In}, month = {September 1, 197}, pages = {133-146}, publisher = {Colorado State University}, address = {Colorado State University, Fort Collins, Colorado}, abstract = { Microbial numbers and biomass have been measured at the Pawnee Site, and some data are available from Comprehensive Sites. Peak bacterial numbers in the surface soil are generally in the range of 20 to 40 x 10(to the 6th power)/g, with some higher values noted at Pawnee. At the Pawnee Site fungal populations have influenced long-term grazing treatments. Higher propagula densities were found on the lightly grazed pastures, but a larger number of high frequency species were present under heavy grazing. Estimates of dry weight microbial biomass at the Pawnee Site indicate a maximum of about 100 g/m2 to a depth of 30 cm. The substrate supply is apparently only sufficient for 5 to 10 generations of cells per year.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, decomposition,grassland, grassland, microbial biomass, grassland,decomposition, grassland,nutrient cycling, microbial biomass, grassland, nitrogen cycling,grassland, nutrient cycling,grassland, proceeding, proceedings}, author = {Reuss, J. O.}, editor = {Norman R. French} } @conference {52434, title = {Drought effects on a southern New Mexico range and the nature of recovery}, booktitle = {21st Annual Meeting, Society for Range Management}, year = {1968}, month = {1968}, pages = {56-57}, keywords = {drought, effects, recovery, southern New Mexico}, author = {C.H. Herbel} } @mastersthesis {52500, title = {Drought and its effect on condition and production of a desert grassland range}, year = {1963}, note = {//NMSU, USDA//NONE//}, month = {1963}, pages = {57}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Drought is a major factor responsible for reduction of herbage production and stand of perennial grasses over wide areas of the Southwestern United States. This study was undertaken to show the relative severity of the 1947-57 drought period in southern New Mexico; show place to placed variation of drought severity of native forage producing perennial grasses to moisture deficiencies. Associated factors of grazing by livestock, rodents and rabbits, mesquite invasion and low production of viable seed are often responsible for retarding recovery of depleted range areas.}, keywords = {dissertation, dissertations, drought, grassland, grassland, drought, history, drought, precipitation, drought, theses, thesis}, author = {Lohmiller, Robert George} } @article {52553, title = {Distance from water as a factor in grazing capacity of rangeland}, journal = {Journal of Forestry}, volume = {45}, year = {1947}, note = {//??//NONE//Journal - short//(New Mexico Agr. Experiment Station Journal Article 44)//}, month = {1947}, pages = {749-754}, abstract = {

An important factor influencing use of range forage is nearness to water supply. The author points out how intensity of grazing use declines with increased distance from water. \ Applying these\  results to a specific pasture made possible a correction ordinary range-carrying capacity estimates to values in accordance with good range use.

}, keywords = {article, articles, grazing management,water, journal, journals, water,grazing management}, url = {/files/bibliography/030.pdf}, author = {Valentine, K. A.} } @article {52557, title = {Determining the grazing use of grasses by scaling}, journal = {Journal of Forestry}, volume = {44}, year = {1946}, note = {//??//NONE//(New Mexico Agr. Experiment Station Journal Article 39)//}, month = {1946}, pages = {528-529}, keywords = {article, articles, grazing management,scaling method, journal, journals}, author = {Valentine, K. A.} }