@proceedings {JRN55371, title = {Nutrient circularity for sustainability in beef supply chains: Comparing the performance of three manureshed approaches}, year = {2022}, month = {4/4/2022}, abstract = {Expectations of the beef industry are multiplying as communities seek to build sustainable agri-food systems for the long term. Nutrient circularity {\textendash} recovering nutrients from manures and post-harvest byproducts and reusing them for agricultural production {\textendash} is a promising yet complex strategy for achieving sustainability goals from grazing pasture to dinner plate. In the United States and Canada, flows of cattle from land-based systems to feedlots in the built environment provide opportunities for circular management, in which concentrated feedlot manure is cycled back onto either corn fed to cattle in the feedlot phase or the hay fed to grazing cattle in {\textquotedblleft}earlier{\textquotedblright} links of the cattle supply chain. However, such flows can span great distances because feedlots that produce large volumes of manure tend to be concentrated in particular regions, but the Corn Belt that could use much of their nutrient loads is in the Upper Midwest and the hay-grazing systems that send cattle to feedlots are widely distributed. Systematically recycling manure from concentrated feedlots back to the land-based systems where cattle originated can help the US and Canadian beef industries meet their goals, but such efforts would require initial investments to transform management practices, trade structures, and social networks. With these major societal investments at stake, a reliable understanding of the tradeoffs of various approaches is needed. In turn understanding tradeoffs requires reliable data about geographically-specific flows coupled with expertise from multiple disciplines to interpret the data. Yet this sort of knowledge is rare. We sought to help fill this knowledge gap by comparing three manure recycling strategies using the conceptual framework of the {\textquotedblright}manureshed{\textquotedblright} {\textendash} the lands where surplus manure nutrients from concentrated animal feeding sites can be recycled to meet production, environmental, and socio-economic goals.}, keywords = {beef supply chains, manureshed, Nutrient circularity, sustainability}, author = {S. Spiegal and Meredith Gwendwr and S. Bittman and Maria Silveira and Jo{\~a}o M.B. Vendramini and C. A. Rotz and Colton K Flynn and Mark Boggess and Peter J. A. Kleinman} } @article {JRN55347, title = {A North American dust emission climatology (2001{\textendash}2020) calibrated to dust point sources from satellite observations}, journal = {Aeolian Research}, volume = {54}, year = {2021}, month = {11/10/2021}, pages = {100766}, abstract = {Measurements of atmospheric dust have long influenced our understanding of dust sources and dust model calibration. However, assessing dust emission magnitude and frequency may reveal different dust source dynamics and is critical for informing land management. Here we use MODIS (500 m) albedo-based daily wind friction estimates to produce a new dust emission climatology of North America (2001{\textendash}2020), calibrated by the novel use of dust point sources from optical satellite observations (rather than being tuned to dust in the atmosphere). Calibrated dust emission occurred predominantly in the biomes of the Great Plains (GP) and North American Deserts (NAD), in broad agreement with maps of aerosol optical depth and dust deposition but with considerably smaller frequency and magnitude. Combined, these biomes produced 7.2 Tg y-1 with contributions split between biomes (59.8\% NAD, 40.2\% GP) due to the contrasting conditions. Dust emission is dependent on different wind friction conditions on either side of the Rocky Mountains. In general, across the deserts, aerodynamic roughness was persistently small and dust sources were activated in areas prone to large wind speeds; desert dust emissions were wind speed limited. Across the Great Plains, large winds persist, and dust emission occurred when vegetation cover was reduced; vegetated dust emissions were roughness limited. We found comparable aerodynamic roughness exists across biomes/vegetation classes demonstrating that dust emission areas are not restricted to a single biome, instead they are spread across an {\textquoteleft}envelope{\textquoteright} of conducive wind friction conditions. Wind friction dynamics, describing the interplay between changing vegetation roughness (e.g., due to climate and land management) and changing winds (stilling and its reversal), influence modelled dust emission magnitude and frequency and its current and future climatology. We confirm previous results that in the second half of the 21st century the southern Great Plains is the most vulnerable to increased dust emission and show for the first time that risk is due to increased wind friction (by decreased vegetation roughness and / or increased wind speed). Regardless of how well calibrated models are to atmospheric dust, assuming roughness is static in time and / or homogeneous over space, will not adequately represent current and future dust source dynamics.}, keywords = {Albedo, dust emission, ecoregions, Land cover type, MODIS, remote sensing}, doi = {10.1016/j.aeolia.2021.100766}, url = {files/bibliography/21-054.pdf}, author = {Mark Hennen and A. Chappell and Brandon Edwards and Akasha M. Faist and Tarek Kandakji and Matthew C. Baddock and Brandi Wheeler and Gayle Tyree and Ronald Treminio and Nicholas Webb} } @article {JRN55333, title = {Nitrogen dynamics after low-emission applications of dairy slurry or fertilizer on perennial grass: a long term field study employing natural abundance of δ15N}, journal = {Plant Soil}, volume = {465}, year = {2021}, month = {6/9/2021}, pages = {415{\textendash}430}, abstract = {Defining the long-term effects of liquid dairy manure (LDM) applied by a recommended low emission method is important to ensure sustainable grass production and dairy operations. We used natural abundance δ15N and conventional measurements in a long term field experiment to better understand the long-term fate of N applied as LDM, mineral fertilizer (MIN) and both (ALT). Methods We investigated the effects of long-term applications of LDM (with low-emission trailing shoe), MIN, and alternating LDM and MIN (ALT) on grass N uptake, soil N stocks, N losses and δ15N natural abundance in grass, soil and fine heavy fraction (silt + clay size heavy soil). Nominal annual rates of total N were 200 and 400 kg ha-1 for MIN and 400 and 800 kg ha-1 for LDM.}, keywords = {Crop N uptake, Fine heavy fraction, Grass herbage, Liquid dairy manure, Mineral fertilizer, Nitrogen use efficiency, Soil N, Δ15N natural abundance}, doi = {10.1007/s11104-021-04998-7}, url = {files/bibliography/21-045.pdf}, author = {H. Zhang and D. E. Hunt and B. Ellert and E. Maillard and Peter J. A. Kleinman and S. Spiegal and D. A. Angers and S. Bittman} } @article {JRN55233, title = {Numerical soil classification supports soil identification by citizen scientists using limited, simple soil observations}, journal = {Soil Science Society of America Journal}, year = {2020}, month = {09/2020}, pages = {1-18}, abstract = {Accurately identifying the soil map unit component at a specific point-location or position within a landscape is critical for implementing sustainable soil management. Recent developments in smartphone-based technologies for characterizing soil profiles, coupled with improved numerical soil classification algorithms, have made it more accessible for non-soil scientists to sample, characterize, and classify soil profiles. The main objective of this study was to evaluate an operational soil classification framework for identifying the soil component at a point-location based on its numerical similarity to the soil components mapped in that area. To implement this testing framework, we used a subset of the United States National Cooperative Soil Survey Soil Characterization Database (NCSS{\textendash}SCD) as our soil profile point dataset and the U.S. Soil Survey Geographic (SSURGO) database for querying profile data of mapped soil classes in the area surrounding each point. Numerical similarity was tested using soil property data representing different degrees of generalization, both in terms of geographic space (i.e., depth-wise variably) and feature space (e.g., texture class vs. clay percentage). Three soil property groups (i.e., Novice, Expert, Expert-Plus) representing different levels of experience required for their measurement and three types of depth-support (i.e., genetic horizon, depth intervals, and depth functions) were evaluated. Using a simple set of soil property inputs (i.e., Novice: soil texture class,rock fragment volume class, and soil color) resulted in nearly as high classification accuracy (46-53\%) as that achieved with an Expert (48-57\%) dataset that included more precise determinations (percent sand, silt, clay, and rock fragment volume), and virtually no further improvement with the addition of pH and organic matter in the Expert-Plus dataset (53-60\%). A measure of management relevant accuracy was assessed using correlated Ecological Sites (ESDs) and Land Capability Classifications (LCC) which followed similar trends for the Novice (ESD: 78-82\%; LCC: 70-76\%), Expert (ESD: 79-84\%; LCC: 71-77\%), and Expert-Plus (ESD: 83-85\%; LCC: 74-79\%) datasets. This study also showed minimal effect from the type of depth-support used to represent depth-wise variability.}, keywords = {characterizing soil profiles, landscape, numerical, smartphone-based technologies, soil classification algorithms, soil map unit component, specific point-location, sustainable soil management}, doi = {https://doi.org/10.1002/saj2.20119}, url = {files/bibliography/20-030.pdf}, author = {Jonathan Maynard and S. W. Salley and D. Beaudette and Jeffrey E. Herrick} } @article {JRN55165, title = {A note on the use of drag partition in aeolian transport models}, journal = {Aeolian Research}, volume = {42}, year = {2020}, month = {01/01/2020}, abstract = {

Sediment transport equations used in wind erosion and dust emission models generally incorporate a threshold for particle motion (u*t) with a correction function to account for roughness-induced momentum reduction and aerodynamic sheltering. The prevailing approach is to adjust u*t by the drag partition R, estimated as the ratio of the bare soil threshold (u*ts) to that of the surface in the presence of roughness elements (u*tR). Here, we show that application of R to adjust only the entrainment threshold (u*t = u*ts/R) is physically inconsistent with the effect of roughness on the momentum partition as represented in models and produces overestimates of the sediment flux density (Q). Equations for Q typically include a wind friction velocity scaling term (u*n). As Q scales with wind friction velocity at the soil surface (uS*), rather than total wind friction velocity uT* (implicitly u* in models), u*n must be also adjusted for roughness effects. We further note that the practice of reducing Q by the vegetation cover fraction to account for the physically-protected surface area constitutes double accounting of the surface protection when R is represented through the basal-to-frontal area ratio of roughness elements (s) and roughness density (\&$\#$39;). If the drag partition is implemented fully, additional tuning for surface protection is unnecessary to produce more accurate aeolian transport estimates. These findings apply equally to models of the vertical dust flux.

}, keywords = {Aeolian threshold, dust emission, friction velocity, roughness, Shear stress partitioning, wind erosion}, doi = {10.1016/j.aeolia.2019.100560}, url = {files/bibliography/20-003.pdf}, author = {Nicholas Webb and A. Chappell and Susan LeGrand and N. Ziegler and Brandon Edwards} } @conference {JRN54996, title = {A New Institution to Promote Resilience-Based Rangeland Management in Mongolia}, booktitle = {72}, year = {2019}, month = {02/2019}, publisher = {Society for Range Management Meeting Abstracts}, organization = {Society for Range Management Meeting Abstracts}, address = {Minneapolis, Minnesota}, abstract = {

Rangelands are fundamental to Mongolian agriculture and society, occupying over 80\% of the country{\textquoteright}s land area. Concern about rangeland degradation has been accelerating, however, associated with ever-increasing livestock numbers and the breakdown of traditional governance systems over the past two decades. Since 2008, the donor-backed organization Green Gold Mongolia has established a comprehensive resilience-based rangeland management strategy that integrates rangeland monitoring and evaluation based on Ecological Site Descriptions with rangeland management strategies. Management is implemented via multi-tiered community organizations known as {\textquotedblleft}Pasture User{\textquoteright}s Groups{\textquotedblright} in which herder groups and local government design, implement, and monitor the effectiveness of grazing plans. Pasture User{\textquoteright}s Groups have been organized into higher levels of organization in order to advance training and marketing of livestock products based on environmental quality and animal health. The National Federation of Pasture User{\textquoteright}s Groups (NFPUG) was recently established to sustain linkages among production, marketing, monitoring, science, and management in Mongolia{\textquoteright}s rangelands. The NFPUG coordinates with government agencies and international donors, including in the production of periodic national reports on rangeland health and new technologies to advance environment-based certification and tracking of livestock products. The NFPU presents a locally-tailored and innovative solution to rangeland management in Mongolia that could be extended well beyond its borders.

}, author = {Bulgamaa Densambuu and Burmaa Dashbal and Gankhuyag N. Ochir and Sumjidmaa Sainnemekh and Budbaatar Ulambayar and Brandon T Bestelmeyer} } @article {JRN54650, title = {Nematode exclusion and recovery in experimental soil microcosms}, journal = {Soil Biology and Biochemistry}, volume = {108}, year = {2017}, pages = {78-83}, abstract = {

Experimental manipulations of soil fauna are a powerful tool for assessing causal relationships between belowground biodiversity and key ecosystem properties. However, preparing soil microcosm treatments without soil fauna for ecological experiments can be problematic. Methods to exclude nematodes, a ubiquitous and functionally important component of terrestrial ecosystems, have been developed for a few specific ecosystems, some of them involving the application of nematicides that may have interactive effects throughout the soil food web. Our goal was to develop a method to remove nematodes from soils of three Long Term Ecological Research (LTER) grassland sites, ranging from desert to moist, without use of chemicals and with moderate disturbance. Moreover, we aimed at testing whether the nematode removal would remain effective up to several weeks later. The following treatments were applied to ~3- kg soil microcosms in the laboratory: (1) a 72 h heating (65 C) - freezing (-20 C) - heating (65 C) cycle using soil maintained at its original water content, and pre-wetting soil 24 h before heating (65 C) for either (2A) 48 h or (2B) 24 h.We measured treatment effects on total abundance and trophic structure of the nematode community. To investigate whether nematodes would recolonize eight weeks after treatments, we conducted a greenhouse experiment where individual seedlings of the dominant grass species for each ecosystem were transplanted to treated and non-treated (control) soils. A heat-freezeheat cycle of 72 h using soil in its original field water content killed 60, 95, and 99\% of the nematodes for the desert, semi-arid, and moist tallgrass prairie soils, respectively. Pre-wetting soil before heating increased mortality to 99\% for all ecosystems after only 24 h at 65 C. Root-feeders were the most resistant nematode trophic group. Eight weeks after treatments, there was no significant nematode recolonization for the pre-wetted 48 h heated soils from the three sites, while for the semi-arid and moist sites there was a slight recovery in abundance in soil from the 24 h heating treatment. Therefore, a treatment at 65 C for 48 h using pre-wetted soil is recommended for eight-week long manipulative experiments in order to assure the effectiveness of the nematode removal throughout the experiment. {\textcopyright} 2017 Elsevier Ltd. All rights reserved.

}, keywords = {grasslands, intersite, LTER, nematode removal, soil defaunation, soil microcosm}, doi = {10.1016/j.soilbio.2017.02.001}, url = {files/bibliography/JRN00658.pdf}, author = {A. C. Franco and Knox, Matthew A. and Andriuzzi, Walter S. and Cecilia M. de Tomasel} } @article {JRN54695, title = {Neighborhood size of training data influences soil map disaggregation}, journal = {Soil Science Society of America Journal}, volume = {81}, year = {2017}, month = {04/2017}, pages = {354-368}, abstract = {
Soil class mapping relies on the ability of sample locations to represent portions of the landscape with similar soil types; however, most digital soil mapping (DSM) approaches intersect sample locations with one raster pixel per covariate layer regardless of pixel size. This approach does not take into account the variability of covariate information adjacent to training data that represent the polypedon. My objective was to disaggregate a soil map in a semiarid Arizona rangeland (78,569 ha) by exploring different neighborhood sizes for extracting covariate data to points. Eight machine learning algorithms were compared to assess the influence of aggregating covariate data in neighborhood sizes between 0 {\textendash} 180 m radius and a multi-scale model. Kappa values of all models ranged between 0.24 and 0.44 and increased with buffer radius up to a radius of 150 m. Support vector machine and random forest algorithms performed best across all scales. The radial support vector machine model using 150 m aggregations of covariates had the highest kappa and produced a more generalized map compared to the best multi-resolution model (random forest) which resulted in a mix of general and detailed soil features. Evaluating a range of neighborhood sizes for aggregating covariate data provides a method of accounting for multi-scale processes important for predicting soil patterns without modifying pixel size of final maps. Incorporating polypedon concepts from traditional soil survey with DSM approaches can strengthen ties between them and optimize the extraction of landscape information for predicting soil properties.
}, doi = {10.2136.sssaj2016.08.0258}, url = {/files/bibliography/17-007.pdf}, author = {Matthew Levi} } @article {JRN54602, title = {Numerical simulation of a dust event in northeastern Germany with a new dust emission scheme in COSMO-ART}, journal = {Atmospheric Environment}, volume = {126}, year = {2016}, month = {02/2016}, type = {Peer Reviewed}, chapter = {87}, abstract = {The dust emission scheme of Shao (2004) has been implemented into the regional atmospheric model COSMO-ART and has been applied to a severe dust event in northeastern Germany on 8th April 2011. The model sensitivity to soil moisture and vegetation cover has been studied. Soil moisture has been found to be relatively high in the model during the investigation period and has been reduced by different degree to investigate the resulting changes in dust emissions. Two different vegetation datasets have been tested as model input: the climatological vegetation cover data of COSMO-ART (ECOCLIMAP) and the SPOT5 remote sensing vegetation cover data for the time of the event. By varying soil moisture, vegetation cover and by restricting the potential emission area, a set of eleven simulations was generated. Vegetation cover during the event was about 24\% lower on average compared to the climatological mean. Thus, dust emissions modeled with SPOT5 vegetation exceeded that modeled with climatological data by a factor of about 5. The modeled dust concentrations were compared with in-situ measurements of aerosol concentration. The temporal evolutions of simulations and observations have significant correlations (0.42 - 0.85) especially in rural backgrounds. The lower correlations at urban sites are attributed to anthropogenic PM10 sources, which are not included in the model. However, a verification of the magnitude of modeled dust concentrations is not possible due to the uncertainty in soil moisture and emission area. }, url = {/files/bibliography/16-020.pdf}, author = {Deetz, K. and Martina Klose and Kirchner, I. and Cubasch, U.} } @article {JRN54603, title = {A numerical study on dust devils with implications to global dust budget estimates}, journal = {Aeolian Research}, volume = {22}, year = {2016}, month = {09/2016}, type = {Peer Reviewed}, chapter = {47}, abstract = {The estimates of the contribution of dust devils (DDs) to the global dust budget have large uncertainties because the dust emission mechanisms in DDs are not yet well understood. In this study, a large-eddy simulation model coupled with a dust scheme is used to investigate DD dust entrainment. DDs are identified from the simulations using various threshold values for pressure drop and vorticity in the DD center. A vortex-tracking algorithm is presented, which automatically detects and tracks vortices based on different pressure drop and vorticity criteria. The results show that DD dust lifting can be largely explained by convective turbulent dust emission. DD dust entrainment varies strongly between individual DDs even for similar atmospheric conditions, but the maximum emissions are determined by atmospheric stability. By relating DD emission and counts to the Richardson number, we propose a new and simple method to estimate regional and global DD dust transport. }, url = {/files/bibliography/16-019.pdf}, author = {Martina Klose and Shao, Yaping} } @article {JRN54518, title = {The Natural Resources Conservation Service land resource hierarchy and ecological sites}, year = {2016}, abstract = {Resource areas of the NRCS have long been important to soil geography. At both regional and landscape scales, resource areas are used to stratify programs and practices based on geographical areas where resource concerns, problems, or treatment needs are similar. However, the inability to quantifiably delineate and classify resource area boundaries hinders communication across the NRCS and federal agencies. Without strong standards delineating geography and concepts, resource areas become less scientifically defensible and inconsistent in addressing similar resource management issues. Furthermore, with continued development of Ecological Site concepts, there is a renewed interest in understanding the relationships between resource areas and Ecological Sites. In this paper we: (i) review the concepts and history of landscape classifications leading to the predominant regional classification systems used by federal agencies in the United States, (ii) propose strengthening the NRCS{\textquoteright}s Land Resource Hierarchy by building resource area concepts on nesting principles of subdivision instead of aggregation, and (iii) place ecological site concepts as a nested resource area within the Land Resource Hierarchy.}, doi = {10.2136/sssaj2015.05.0305}, url = {/files/bibliography/16-005.pdf}, author = {S. W. Salley and Curtis Talbot and Joel R. Brown} } @article {JRN54601, title = {A note on the stochastic nature of particle cohesive force and implications to threshold friction velocity for aerodynamic dust entrainment}, journal = {Aeolian Research}, volume = {22}, year = {2016}, month = {09/2016}, type = {Peer Reviewed}, chapter = {123}, abstract = {There is considerable interest to determine the threshold for aeolian dust emission on Earth and Mars. Existing schemes for threshold friction velocity are all deterministic in nature, but observations show that in the dust particle size range the threshold friction velocity scatters strongly due to stochastic interparticle cohesion. In the real world, there always exists a certain amount of free dust which can be easily lifted from the surface by weak winds or even turbulence, as exemplified by dust devils. It has been proposed in the dust-devil research community, that the pressure drop at dust-devil center may be a major mechanism for dust-devil dust emission, known as the {\textquoteright}p effect. It is questioned here whether the {\textquoteright}p effect is substantial or whether the elevated dust concentration in dust devils is due to free dust emission. A simple analysis indicates that the {\textquoteright}p effect appears to be small and the dust in dust devils is probably due to free dust emission and dust convergence. To estimate free dust emission, it is useful to define a lower limit of dust-particle threshold friction velocity. A simple expression for this velocity is proposed by making assumptions to the median and variance of inter-particle cohesive force. The simple expression is fitted to the data of the Arizona State University Vortex Generator. While considerable uncertainty remains in the scheme, this note highlights the need for additional research on the stochastic nature of dust emission. }, url = {/files/bibliography/16-018.pdf}, author = {Shao, Yaping and Martina Klose} } @article {JRN54575, title = {The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management}, journal = {Aeolian Research}, volume = {22}, year = {2016}, month = {05/2016}, pages = {23-36}, chapter = {23}, abstract = {

The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture{\textquoteright}s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: 1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, 2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and 3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties which influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

}, keywords = {aeolian, dust emission, Long-Term Agroecosystem Research, monitoring, Network, wind erosion}, doi = {10.1016/j.aeolia.2016.05.005}, url = {/files/bibliography/16-010.pdf}, author = {Nicholas Webb and Jeffrey E. Herrick and Justin Van Zee and Ericha Courtright and Hugenholtz, Christopher and Teddy M. Zobeck and Gregory S. Okin and Barchyn, Thomas and Billings, Benjamin and Boyd, Robert and Clingan, Scott and Brad Cooper and Danielle Duni and J. D. Derner and Fox, Fred A. and Kris Havstad and Phil Heilman and Valerie LaPlante and Ludwig, Noel and Loretta Metz and Mark A. Nearing and Norfleet, M.L. and Frederick B. Pierson and Matt A Sanderson and Brenton Sharrat and Jean Steiner and John Tatarko and Negussie Tedela and David P. Toledo and Unnasch, Robert S. and Scott Van Pelt and Wagner, Larry E.} } @conference {JRN54637, title = {The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management}, 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 = {
The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the USDA Agricultural Research Service and Natural Resources Conservation Service, and USDI Bureau of Land Management, to address the need for a broad and coordinated research program to develop wind erosion research and management in the United States. The National Wind Erosion Research Network has three general aims: 1) provide data to support understanding of basic aeolian processes across land use and land cover types and for different management practices, 2) support the development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and 3) encourage collaboration between the aeolian research community and land management agencies to increase the impact of aeolian research for the wider community. By applying standardized methods, the Network will overcome the common challenge of synthesizing independent studies to assess local-to-national scale wind erosion and dust emission and their impacts. Twelve intensively instrumented Network sites will be operational in 2016, providing high-resolution measurements of aeolian sediment transport rates, meteorological conditions and soil and vegetation properties that influence dust emission, transport and deposition. These initial sites are located across the rangelands, croplands and deserts of New Mexico, Texas, Arizona, California, Colorado, Utah, North Dakota, Idaho and Washington. In support of Network activities, winderosionnetwork.org was developed to serve as a data portal and access to online information about the National Wind Erosion Research Network, including site descriptions, measurement protocols and results. The website provides a comprehensive resource for scientists and managers interested in collaborating with the Network and accessing Network data products. The Network provides exciting opportunities to engage in a national long-term wind erosion research program that promises significant impact for our understanding and ability to predict and evaluate aeolian processes across land cover types and land use systems.
}, author = {Nicholas Webb and Jeffrey E. Herrick and Justin Van Zee and Ericha Courtright and Brad Cooper and Valerie LaPlante} } @conference {JRN54208, title = {A national wind erosion research network}, booktitle = {18th International Soil Conservation Organization Conference}, year = {2015}, month = {05/2015}, address = {El Paso, Texas}, abstract = {

Public concern about wind erosion in the United States is high. This concern has arisen as a consequence of changing and intensifying land use pressures which can lead to increased soil loss and dust emission. However, there is relatively little research to support improved management. While much attention has been given to measuring and modelling wind erosion in US croplands, little information is available on the magnitude and frequency of wind erosion in rangelands and other land cover types. Resolving this knowledge gap is important for soil conservation in the face ongoing land use change, land cover change and climate change. Predictive models supported by high quality, spatially-diverse field measurements are needed to quantify wind erosion across all land cover types so that the impacts can be assessed and management options identified and tested. We present a National Wind Erosion Research Network to support field assessments of wind erosion in all land cover types and the development of an all-lands wind erosion model. We describe the establishment of the network field sites, supported by the US Department of Agriculture{\textquoteright}s Long-Term Agroecosystem Research (LTAR) network, Natural Resources Conservation Service (NRCS), Bureau of Land Management (BLM), and Department of Defence (DoD), and outline a standard methods protocol developed to ensure consistency in wind erosion monitoring and assessment across the network. The network will provide opportunities to evaluate controls on the timing and intensity of wind erosion across land use and land cover types in the United States. These data, in support of an all-lands wind erosion model, will provide much needed tools for managing wind erosion and its impacts.

}, author = {Nicholas Webb and Jeffrey E. Herrick and Hugenholtz, Christopher and Teddy M. Zobeck and Gregory S. Okin} } @article {JRN54655, title = {A new landscape classification system for monitoring and assessment of pastures}, journal = {Journal of Soil and Water Conservation}, volume = {69:17A-21A}, year = {2014}, abstract = {

Pasturelands in the United States span a broad range of climate, soils, physical sites, and management. Rather than treat each site as a unique entity, this diversity must be classified into basic units for research and management purposes. A similar system based on ecological principles is needed for temperate semiarid to subhumid to humid areas. Forage suitability groups (FSG; a system based on soil types) offer one approach for doing so, but are heavily based on expert opinion and management regime. A quantitative scientifically-based system like the ecological site description scheme (ESD) used in rangelands would provide a uniform approach to assessing all grazing lands, allow the identification of reference states for monitoring and assessment, and facilitate the creation of state and transition models suitable for pasture systems. We propose a new system based on a probabilistic hierarchical classification of ecologically-relevant climatic, topographic and edaphic variables, which will provide continuity in assessing ecological services across a broad spectrum of grazing lands.

}, doi = {10.2489/jswc.691.17A}, author = {Sarah Goslee and Matt A Sanderson and K. Spaeth and Jeffrey E. Herrick and Ogles, Kevin} } @article {JRN53986, title = {North American Biomes}, journal = {Oxford Bibliographies}, year = {2014}, month = {08/2014}, abstract = {

The North America biome includes the major ecoregions that make up the land area of Canada, the United States, Mexico, and countries in Central America. The biome is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. This large area (over 24 x 106 km2) is characterized by a broad range of temperature and precipitation that result in nine major ecoregions, from boreal forests and tundra near the North Pole to tropical deciduous and coniferous forests in the south near the equator.\  Temperate forests (deciduous, coniferous), grasslands and shrublands, savannas, and deserts occur in the central part. Landscape-scale patterns in contemporary ecosystems within each ecoregion reflect variability in climate and soil parent material combined with human activities that have increased in extent and intensity over the past several centuries. Within the biome, ecoregions can be influenced by the movement of organisms, water and sediment, fire, and air chemistry from other ecoregions in the biome. At the scale of the biome, connections with other locations on Earth can lead to invasion by exotic species including pests and pathogens, large climatic events such as hurricanes and drought, and changes in air quality through dust storms and volcanic eruptions. These tele-connections often occur infrequently, yet with large and surprising effects on ecosystem properties and dynamics. Increasing awareness of these broad-scale dynamics that connect biomes globally is leading to new avenues of research that intersect ecology with other disciplines.

}, doi = {10.1093/OBO/9780199830060-0099}, author = {Debra C. Peters and Stacey L P Scroggs and Jin Yao} } @conference {JRN54430, title = {The NDVI: Back to basics}, booktitle = {American Geophysical Union}, year = {2014}, month = {12/2014}, address = {San Francisco, CA}, abstract = {

Ease of access to satellite sensor imagery and image products has driven the use of remote sensing data in many disciplines, including landscape ecology, forestry, environmental and wildlife management, agriculture, and epidemiology. A common format of these data is as vegetation indices and of these the most widely used is the Normalized Difference Vegetation Index (NDVI). There are many examples where the NDVI has been assessed as a covariate in spatial models of ecosystem health, faunal habitat, faunal distribution and condition, forage quality and disease risk, to name but a few. Occasionally, such applications detach the NDVI from its theoretical underpinnings; there may be no consideration of surface phenomena affecting the radiation environment and causing change in red and near infrared (NIR) reflectance. In this paper, we revisit classic remote sensing research to determine for which environmental modeling applications the NDVI is likely to be meaningful. We collated data from multiple published research studies to characterize the relationships between NDVI and vegetation canopy variables (leaf area index, biomass, percentage cover, and the fraction of absorbed radiation) over different vegetation types. Using these collated data sets, we discuss the physical basis of the relationships between NDVI and vegetation canopy variables, how and why these relationships differ, and what this means for the usefulness of the NDVI as a proxy for Earth surface or climate variables. We conclude with a critique of the variables that NDVI has been used to replace as a proxy and show its success or failure as a proxy variable relates back to the simple relationships known to exist between NDVI and vegetation canopy variables.\  Abstract B42C-01.

}, author = {Caitriana Steele and Alistair Smith and Dawn M. Browning} } @proceedings {JRN54043, title = {A National Wind Erosion Monitoring Network to support and all-lands wind erosion model}, year = {2014}, month = {07/2014}, pages = {p. 427}, publisher = {International Society of Aeolian Research (ISAR)}, address = {Lanzhou, China}, abstract = {

Public concern about wind erosion in the United States rangelands is increasing. This concern has arisen as a consequence of changing and intensifying land use pressures which can lead to increased soil loss and dust emissions. However, there is relatively little research to support improved management. While much attention has been given to measuring and modelling wind erosion in US cropping systems, there is a dearth of information on the magnitude and frequency of wind erosion in rangelands and other land cover types. Resolving this knowledge gap is important for addressing the multiple impacts of land use and land cover change, including those related to soil nutrient loss and productivity, snow hydrology, public health and climate. Field measurements of aeolian sediment transport rates supported by predictive models are needed to quantify wind erosion across all land cover types so that the impacts can be assessed and management solutions identified and tested. We present a new National Wind Erosion Monitoring Network to support field assessments of wind erosion in all land cover types and the development of an all-lands wind erosion model. We describe the establishment of the network field sites, supported by the US Department of Agriculture\’s Long-Tern Agroecosystem Research (LTAR) network, Natural Resources Conservation Service and Bureau of Land Management, and outline a standard methods protocol developed to ensure consistency in wind erosion monitoring and assessment across the network. The network will provide opportunities to evaluate controls on the timing and intensity of wind erosion in a number of land uses and land cover types across the United States. These data, in support of an all-lands wind erosion model, will provide much needed tools for managing wind erosion and its impacts.

}, author = {Nicholas Webb and Jeffrey E. Herrick and Hugenholtz, Christopher and Gregory S. Okin and Teddy M. Zobeck} } @inbook {JRN52685, title = {New ecology education: Preparing students for the complex human-environmental problems of dryland East Asia}, booktitle = {Dryland East Asia; Land Dynamics Amid Social and Climate Change}, year = {2013}, pages = {363-403}, publisher = {Higher Education Press}, organization = {Higher Education Press}, chapter = {16}, address = {Beijing, China}, abstract = {

Present-day environmental problems of Dryland East Asia are serious, and future prospects look especially disconcerting owing to current trends in population growth and economic development.\  Land degradation and desertification, invasive species, biodiversity losses, toxic waste and air pollution, and water depletion are exacting serious economic losses, social conflicts and health costs.\  The list of stakeholders expected to resolve these problems include scientific researchers, government regulators, environmental engineers, business consortiums, resource managers and policy-makers.\  While all are crucial, in this chapter we focus on an often overlooked {\textendash} but exceptionally important stakeholder {\textendash} students.\  Given both the rapid rate and magnitude of change that have already occurred, it{\textquoteright}s not surprising that students often sense that the extent of future environmental problems are so overwhelming that there are not adequate means of fully understanding them.\  Consequently, educators have the task of instilling a sense of optimism that while the challenge is difficult, it is not impossible.\  We must assist students develop a suite of skills that will enable them to deal with the prodigious mix of societal and environmental problems that they stand to inherit.\  Towards this end, in this chapter we present our vision of a new ecology education course.\  Three key topics are new ecology education emphasize interdisciplinary and multidisciplinary approaches; the role of strong conceptual frameworks; the importance of nonlinearities, thresholds and feedbacks in human-environmental systems; principles of both systems and resilience theory; and how short-term versus long-term solutions to any given problem may be quite different.\  Decision-making ultimately relies upon identifying and evaluating choices; thus the next generation of students must be effective communicators, problems-solvers, and systems thinkers.

}, author = {Ye, Jiansheng and J. F. Reynolds and Jeffrey E. Herrick and Julie A. Reynolds and Chuluun, Togtohyn and Li, Fengmin and Long, Ruijun} } @article {49888, title = {Nematodes as an indicator of plant{\textendash}soil interactions associated with desertification}, journal = {Applied Soil Ecology}, volume = {58}, year = {2012}, month = {04/2012}, pages = {66-77}, chapter = {66}, abstract = {

Conversion of perennial grasslands to shrublands is a desertification process that is important globally. Changes in aboveground ecosystem properties with this conversion have been well-documented, but little is known about how below ground communities are affected, yet these communities may be important drivers of desertification as well as constraints on the\ \  reversal of this state change. We examined nematode community structure and feeding as a proxy for soil biotic change across a\  desertification gradient in southern NM, USA. We had two objectives: (1) to compare nematode trophic structure and species\  diversity within vegetation states representing different stages of desertification, and (2) to compare nematode community structure\  between bare and vegetated patches that may be connected via a matrix of endophytic fungi and soil biotic crusts. The gradient\  included a perennial grassland dominated by Bouteloua eriopoda, the historic dominant in the Chihuahuan Desert, a duneland\  dominated by the shrub, Prosopis glandulosa, and the ecotone between them. We also sampled a relatively undisturbed, ungrazed B. eriopoda grassland at a nearby site to serve as an end member of our gradient. Nematode communities were sampled using soil cores to depth of 50 cm at\  each location in 2009 and 2010. Results showed that grasslands and mesquite dunelands had different trophic groupings and\  herbivorous nematode communities with lower species diversity and evenness compared with the ecotone. Nematode trophic\  structure and herbivore communities were significantly different in all vegetation states with the highest observed diversity in the\  undisturbed, ungrazed B. eriopoda grassland in 2010. Vegetated and bare ground patches within the two grassland sites had similar\  herbivore communities, especially species from the family Tylenchinae. However, the mesquite duneland showed the lowest sampled diversity of all sites, but had significantly larger nematode abundances in vegetated dunes than interdune areas that are void of\  vegetation and soil biotic crusts where bacteriovores dominated. Decreased nematode trophic structure and species diversity in the\  Jornada black grama grassland samples compared with the undisturbed grassland illustrate the effect of desertification on the soil\  biotic community. Our results show that nematodes can be used to identify changes in belowground community structure based on trophic interactions. Large-scale disturbances like desertification can have consequences on the diversity and soil biotic functioning at finer spatial scales.

}, keywords = {Bouteloua eriopoda, connectivity, Nematode communities, Nematode diversity, prosopis glandulosa, semi-arid grasslands}, doi = {10.1016/j.apsoil.2012.03.005}, url = {/files/bibliography/12-009.pdf}, author = {Jeremy R. Klass and Debra C. Peters and Trojan, Jacqueline M. and S. Thomas} } @conference {49988, title = {Non-linear ecosystem response to long-term changes in precipitation and nitrogen availability in a desert grassland}, booktitle = {96th ESA Annual Meeting, Earth Stewardship: Preserving and enhancing earth{\textquoteright}s life-support systems}, year = {2011}, month = {08/2011}, publisher = {ESA}, organization = {ESA}, address = {Austin, Texas}, abstract = {Our objective was to assess ecosystem responses to long-term changes in precipitation and nitrogen availability in the Northern Chihuahuan Desert (NM, USA), using rainfall manipulations (80\% reduced PPT, ambient, 80\% increased) and fertilization additions (with and without ammonium nitrate) for five consecutive years. Our results show that differences in ANPP among treatments increased with time since the beginning of the manipulation. After year one, ANPP decreased 20\% with drought and increased 30\% with irrigation. But after the fourth year, drought treatments were 50\% less productive than ambient PPT treatments, and irrigated plots were 50\% more productive than ambient. This response was mostly driven by changes in grass productivity because shrub and forb ANPP did not change among treatments or with time. After 5 years of manipulations, species richness, diversity, and evenness? were higher in ambient PPT treatments. Drought and irrigated plots had similar species richness but differed in species identity. Fertilization did not have a significant effect on ANPP across years, but had higher diversity compared to ambient nitrogen plots. Soil nitrogen availability decreased with increasing PPT after the first year of manipulations, and this response was similar across all years. Soil organic carbon increased with PPT but decreased with fertilization. Long-term manipulations revealed time-lags in the ecosystem response to changes in PPT and N. We found hierarchical responses ranging from changes in ANPP and functional group cover to species composition and soil properties that were manifest in a short-term study.}, author = {Lara Reichmann and O. E. Sala and Laureano A. Gherardi and Debra C. Peters} } @article {50004, title = {Nitrogen limitation in arid-subhumid ecosystems: A meta-analysis of fertilization studies}, journal = {Journal of Arid Environments}, volume = {75}, year = {2011}, pages = {675-680}, abstract = {

Evidence supporting water limitation in arid-semiarid ecosystems includes strong correlations between aboveground net primary production (ANPP) and annual precipitation as well as results from experimental water additions. Similarly, there is evidence of N limitation on ANPP in low precipitation ecosystems, but is this a widespread phenomenon? Are all arid-semiarid ecosystems equally limited by nitrogen? Is the response of N fertilization modulated by water availability?

We conducted a meta-analysis of ANPP responses to N fertilization across arid to subhumid ecosystems to quantify N limitation, using the effect-size index R which is the ratio of ANPP in fertilized to control plots. Nitrogen addition increased ANPP across all studies by an average of 50\%, and nitrogen effects increased significantly (P\ =\ 0.03) along the 50{\textendash}650\ mm\ yr-1 precipitation gradient. The response ratio decreased with mean annual temperature in arid and semiarid ecosystems but was insensitive in subhumid systems. Sown pastures showed significant (P\ =\ 0.007) higher responses than natural ecosystems. Neither plant-life form nor chemical form of the applied fertilizer showed significant effects on the primary production response to N addition. Our results showed that nitrogen limitation is a widespread phenomenon in low-precipitation ecosystems and that its importance increases with annual precipitation from arid to subhumid regions. Both water and N availability limit primary production, probably at different times during the year; with frequency of N limitation increasing and frequency of water limitation decreasing as annual precipitation increases. Expected increase N deposition, which could be significant even in arid ecosystems, would increase aboveground net primary production in water-limited ecosystems that account for 40\% of the terrestrial surface.

}, keywords = {arid ecosystems, article, journal, meta-analysis, nitrogen fertilization, primary production, resource limitation}, doi = {10.1016/j.jaridenv.2011.03.003}, url = {files/bibliography/JRN00579.pdf}, author = {Laura Yahdjian and Laureano A. Gherardi and O. E. Sala} } @article {50034, title = {National ecosystem assessment supported by scientific and local knowledge}, journal = {Frontiers in Ecology and the Environment}, volume = {8}, year = {2010}, pages = {403-408}, abstract = {

An understanding of the extent and severity of land degradation and recovery is necessary to guide land use policy and management, yet currently available assessments are widely known to be inadequate. We describe results of the first statistically-based application of a new approach to national assessments that integrates scientific and local knowledge. Qualitative observations completed at over 10,000 plots in the United States showed that while soil degradation remains an issue, loss of biotic integrity is more widespread. Quantitative soil and vegetation data collected at the same locations support the assessments and serve as a baseline for monitoring the effectiveness of policy and management, including responses to climate change. For example, non-native species currently occur on nearly 50\% of non-federal rangelands, and account for at least 50\% of plant cover on over 5\% of these lands. These results provide information necessary to support strategic decisions by land managers and policy-makers.

}, doi = {10.1890/100017}, url = {/files/bibliography/10-035.pdf}, author = {Jeffrey E. Herrick and Lessard, Veronica C. and K. Spaeth and P. L. Shaver and R. Dayton and D.A. Pyke and Jolley, Leonard and Goebel, J. Jeffrey} } @article {50328, title = {A non-destructive and rapid method to estimate biomass and aboveground net primary production in arid environments}, journal = {Journal of Arid Environments}, volume = {69}, year = {2007}, note = {//Other//LTER-V//entered 08/15/2007}, month = {2007}, pages = {352-358}, abstract = {

We present the calibration of a fast and non-destructive method to estimate aboveground plant biomass measuring vegetation cover. We double-sampled vegetation cover and aboveground biomass in the Patagonian steppe using 150 plots for shrubs and 50 plots for grasses. We performed simple linear regressions between vegetation cover and biomass for the dominant species and life forms (shrubs: Mulinum spinosum, Senecio filaginoides, and Adesmia campestris; grasses: Poa ligularis, Stipa speciosa, and Stipa humilis). All regressions were significant (po:01) for green and total biomass. Whereas all grass species had similar slopes, shrub slopes differed among each other with S. filaginoides and A. campestris having the steepest slopes for green and total biomass, respectively (po:05). Life-form calibrations showed steeper slopes for shrubs than for grasses (po:05). Our regressions are a basis for a non-destructive, rapid, and inexpensive way of estimating green biomass, aboveground net primary production (ANPP), and forage availability. Our life-form equations very likely could be used to estimate biomass and ANPP in other arid ecosystems dominated by tussock grasses and shrubs. {\textcopyright}2006 Elsevier Ltd. All rights reserved.

}, keywords = {article, journal, method, aboveground net primary production, method, ANPP, method, calibration, method, double sampling, method, vegetation cover, Patagonian steppe}, doi = {10.1016/j.jaridenv.2006.09.008}, url = {files/bibliography/JRN00466.pdf}, author = {P. Flombaum and O. E. Sala} } @conference {50341, title = {New frontiers for ecosystem services}, booktitle = {60th Annual Meetings and Trade Show, Society for Range Management}, year = {2007}, month = {February 9, 2007}, pages = {Paper No. 188}, address = {Reno/Sparks, NV}, abstract = {The over 300 million ha of public and private rangelands in the United States are characterized by low and variable precipitation, nutrient-poor soils, and high spatial and temporal variability in plant production. This land type has provided a variety of goods and services, with the provisioning of food and fiber dominating through much of the 20th Century. More recently, food production from a rangeland-based livestock industry is often pressured for a variety of reasons, including poor economic returns, increased regulations, an aging rural population, residential development, and increasingly diverse interests of land owners. A shift to other provisioning, regulating, cultural, and supporting services is occurring with important implications for carbon sequestration, biodiversity, and conservation incentives. There are numerous goods and services possible from rangelands that can supply societal demands such as clean water and a safe food supply. The use of ecologically-based principles of land management remains at the core of the ability of private land owners and public land managers to provide these existing and emerging services. We suggest that expectations need to be based on a thorough understanding of the diverse potentials of these lands and their inherent limits. With proper incentives and economic benefits, rangelands, in the U.S. or globally, can be expected to provide both historical provisioning and more unique goods and services in a sustainable fashion, albeit in different proportions than in the past.}, keywords = {precipitation, private, public, rangeland}, author = {Kris Havstad} } @proceedings {50455, title = {New tools for rangeland and pasture monitoring}, year = {2006}, month = {December 10-13, }, pages = {309-314}, address = {St. Louis, MO}, abstract = {This paper describes a set of tools that help land managers easily collect, analyze, interpret and store data that are most relevant to their management objectives. The toolbox includes vegetation and soil methods that are nationally applied by one or more federal agencies, together with additional methods that are appropriate for rangeland, pastureland and can be applied to annual cropping systems. The methods can be applied to small and large farms and ranches, and to large watersheds and are relevant to both production and conservation objectives. The tools include a two-volume manual, a set of Excel spreadsheets that automatically calculate indicators for a single plot, and a computer database/field data entry program that automatically generates and compares indicators for multiple plots. A 40-page "Quick Start" volume provides step-by-step instructions for completing four basic monitoring methods along with rapid semi-quantitative alternative methods. Volume II includes additional methods, a monitoring system design guide, and information to help interpret results and apply them to different management objectives. The Excel Spreadsheets are identical to the paper dataforms printed in the manuals. The Access database/field data entry system includes all of the data entry forms from the manual, together with data forms for other commonly used methods. When applied at the farm or ranch level, no database experience is required. The user simply enters the data as they would on paper, and indicators are automatically generated for each plot. Data can be entered directly in the field using a "Tablet" computer, or on a standard personal computer. Both the monitoring manual and the database/field data entry system were designed as "toolboxes". Different sets of tools are selected for different jobs. The paper describes how to apply the methods to livestock production, wildlife habitat management, control of invasive species and other objectives. It ends with a brief overview of new monitoring tools the Jornada is developing, including Unmanned Aerial Vehicles (UAV{\textquoteright}s) that can be programmed (GPS) to collect high resolution photographs across large areas.}, keywords = {data, managers, monitoring, tools}, url = {/files/bibliography/07-037.pdf}, author = {Jeffrey E. Herrick and Ericha Courtright and Brandon T Bestelmeyer and Laura M. Burkett and Kris Havstad and Andrea S. Laliberte and A. Rango and Repp, J. and Justin Van Zee} } @conference {50474, title = {Native symbiotic fungi increase stress tolerance and productivity of plants in arid lands}, booktitle = {Symposium on Efficient Water Use in the Urban Landscape}, year = {2006}, month = {February 23-24, }, address = {Las Cruces, NM}, abstract = {Plants indigenous to arid lands have evolved to withstand extremes of moisture and temperature. Recent advances in microbial ecology have revealed that a portion of plant stress tolerance comes, not from the plant itself, but from unseen fungi that reside within plant tissues. The ability of these symbiotic fungi to confer drought and salt stress tolerance on plant hosts make them uniquely valuable for landscapes where water is limited or where drip irrigation is utilized. Here we describe fungi associated with four species of Chihuahuan desert plants which can be transferred to non-native hosts. A patent-pending technique was used to transfer these unculturable fungi to native grasses (Bouteloua and Sporobolous species), chile (Capsicum annum), tomato (Lycopersicon esculentum), and shasta daisys (Chrysanthemum maximum). The productivity of recipient plants, measured at various stages in the growth cycle, indicates that fungal recipients fared remarkably well compared to untreated plants receiving equal water and nutrients. Chile plants were also exposed to salt stress trials in which salt stress tolerance varied between endophyte treatments. Fungi from creosote bush (Larrea tridentada) were particularly efficient at increasing salt tolerance.}, keywords = {fungi, microbial ecology, plant stress}, author = {M.E. Lucero and I. Reyes-Vera and Vivenhananthan, E. and J.R. Barrow and Ruth L. Sedillo} } @article {50482, title = {Nonlinear dynamics in arid and semi-arid systems: Interactions among drivers and processes across scales}, journal = {Journal of Arid Environments}, volume = {65}, year = {2006}, month = {April 1, 2006}, pages = {196-206}, abstract = {

We discuss a new conceptual framework for arid and semiarid systems that accounts for nonlinear dynamics and cross scale interactions in explaining landscape patterns and dynamics. Our framework includes a spatial and temporal hierarchy, and five key interacting components that connect scales of the hierarchy: (1) historical legacies that include climate, disturbance, and management regimes, (2) dynamic template of patterns in ecological variables and spatial context, (3) vertical and horizontal transport processes (fluvial, aeolian, animal), (4) the rate, direction, and amount of resource redistribution between high and low resource areas, and (5) feedbacks among plants, animals, and soils. We illustrate how this framework can be used to understand, forecast, and manage ecological systems that exhibit nonlinear dynamics across a range of spatial and temporal scales. This paper provides the foundation for a series of papers from the Jornada Experimental Range ARS-LTER research site in southern New Mexico, USA that support this new conceptual framework.

}, keywords = {across scales, arid, drivers, dynamics, nonlinear, semiarid}, doi = {10.1016/j.jaridenv.2005.05.010}, url = {/files/bibliography/06-007.pdf}, author = {Debra C. Peters and Kris Havstad} } @inbook {50502, title = {Nutrient cycling within an arid ecosystem}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem. The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {133-149}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {6}, address = {New York, NY}, abstract = {In arid and semiarid lands, soil erosion by wind is an important process that affects both the surface features and the biological potential of the ecosystem. The eolian flux of soil nutrients into or out of an ecosystem results in enrichment or impoverishment of its biological potential. In the Jornada Basin, wind erosion is the only significant mechanism for the net loss of soil materials because fluvial processes do not remove materials from the basin. Vigorous wind erosion leads to topographic changes, altering the growing conditions for plants and animals. Examples of such changes in topography are the formation of sand dunes or the removal of whole soil horizons. Our goal in this chapter is to describe the construction of a mathematical model for wind erosion and dust production for the Jornada Basin. The model attempts to answer the following questions:1. Which soils are affected by wind erosion?2. How does wind erosion occur on Jornada soils?3. Does changing vegetation cover lead to a change in the source/sink relationship? 4. Is the Jornada a source or sink of eolian materials? If it is a source, what materials are lost?5. How does wind erosion change the soil-forming process?}, keywords = {cycling, erosion, Jornada, nutrient, semiarid, soil}, url = {/files/bibliography/06-057.pdf}, author = {W. H. Schlesinger and S. Tartowski and Schmidt, S.M.}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @conference {50539, title = {Nighttime transpiration and nutrient acquisition: Is there a benefit of losing water at night?}, booktitle = {Ecological Society of America}, year = {2005}, abstract = {Nighttime stomatal conductance and transpiration can lead to substantial water loss occurring at non-photosynthetic times in C3 and C4 plants. Water loss without simultaneous carbon gain is intuitively wasteful, however it is possible that either there is no cost when water supply is sufficient or that it provides a benefit under certain conditions. For example, the transpiration stream is largely responsible for supplying soil-mobile nutrients (e.g. nitrate) to plant roots, and maintenance of water flux through the soil-plant-air continuum through nighttime transpiration (NT) may enhance nutrient supply to plant roots. In a growth chamber study with 3 ecotypes of Arabidopsis thaliana, nighttime relative humidity was manipulated to suppress or allow NT in plants with sufficient or limited N supply. N-limited plants grown under high nighttime relative humidity (~90\%) showed decreased plant fitness relative to plants in which NT was not suppressed (~55\% RH), indicating that under non-water-limiting conditions, NT benefited N-limited plants. Results for non-N-limited plants varied among ecotypes, suggesting that for some ecotypes relative costs and benefits depended on nutrient supply. In a separate field study, Helianthus anomalus plants given nutrient additions showed decreased day and night conductance and transpiration. To explore the extent to which NT may affect the supply of mobile nutrients to plant roots, the Barber-Cushman model was used to investigate depletion of nitrate at various distances from a rooting zone under different levels of water flux through the system. Results showed that increasing water flux through the system (as with NT) increased N supply to plant roots. Another field study using the desert shrub Sarcobatus vermiculatus showed that plant uptake of 15NO3- decreased slightly when NT was suppressed, although differences were not significant due to low sample sizes. Taken as a whole, there is growing evidence that the magnitude of NT may affect nutrient acquisition of plants.}, keywords = {night, nighttime, nutrient, transpiration}, author = {Caird, M. and J. H. Richards and J. James and Ludwig, F. and L.A. Donovan and K. A. Snyder} } @proceedings {50592, title = {Natural (and Managed) Islands of Hydrologically Enhanced Biotic Productivity in Arid Zones}, volume = {86}, year = {2005}, month = {May 23-27, 2005}, pages = {CDROM A33A-02}, abstract = {Numerous physical characteristics influence runoff generation in arid regions such as the Jornada basin of southern New Mexico. Factors causing high spatial variations of water in deserts include precipitation, soil, physiography, and vegetation characteristics. The inherent heterogeneity of these characteristics in arid zones causes discontinuous areas of runoff and run-on which creates islands of hydrologically enhanced biotic productivity. These hydrologic islands are observed at the plant scale where they coincide with islands of fertility or resource islands. At the larger scale the islands of hydrologically enhanced biotic productivity can be observed as banded vegetation, beaded drainage networks, and playitas and playas. In the rehabilitation of degraded rangelands it is wise to mimic the natural processes which tend to slow down surface flow and allow time for infiltration, thus creating areas of high vegetation productivity. There have been several successful attempts in the Jornada basin to establish spatial discontinuities of water and vegetation similar to natural occurring patterns. The most successful treatments so far have been shallow, water ponding dikes and water spreaders.}, keywords = {biotic, hydrologically, managed, natural}, author = {A. Rango and S. Tartowski and Andrea S. Laliberte and A.J. Parsons and John Wainwright} } @conference {50701, title = {Nonlinear dynamics in arid systems: interactions among drivers and processes across scales}, booktitle = {Sixth Symposium on the Natural Resources of the Chihuahuan Desert Region}, year = {2004}, month = {October 15, 2004}, pages = {38}, address = {Alpine, TX}, abstract = {Conversion from perennial grasslands to shrub-dominated systems has occurred globally in arid and semiarid systems and regionally in the Chihuahuan Desert over the past 100-150 years. Broad-scale drivers, such as grazing and extreme drought, are often invoked to explain shrub invasion dynamics. We use long-term, spatially explicit data to show that these drivers are frequently insufficient to explain patterns in shrub invasion and grass persistence at the landscape scale. At the Jornada Experimental Range, we are developing a new conceptual framework to explain high temporal and spatial variation in landscape patterns and dynamics. Our framework focuses on five key aspects of these systems: (1) threshold behavior, (2) spatially contagious processes, (3) landscape context, (4) feedbacks between biotic and abiotic processes at multiple scales, and (5) landscape legacies. We show how accounting for these key aspects of system behavior can explain nonlinear dynamics across spatial and temporal scales. This talk provides the background for the remaining talks in the special session {\textquotedblleft}Landscape linkages and cross-scale interactions in the Chihuahuan Desert.{\textquotedblright}}, keywords = {arid systems, broad-scale drivers, Chihuahuan Desert, drivers, feedbacks, interactions, landscape contest, nonlinear dynamics, processes, scales, spatially contagious processes, threshold behavior}, author = {Debra C. Peters and Kris Havstad} } @conference {50779, title = {A new standard for qualitative rangeland health assessments}, booktitle = {88th Annual Meeting, Ecological Society of America}, year = {2003}, month = {August 3-8, 2003}, pages = {148}, address = {Savannah, GA}, abstract = {The term rangeland health is increasingly used by land managers to refer to the maintenance of complex ecological processes on rangelands. In an attempt to provide a rapid, moment-in-time assessment of rangeland health, we developed the Interpreting Indicators of Rangeland Health protocol. This protocol uses 17 observable indicators to assess 3 attributes of rangeland health: soil and site stability, hydrologic functioning and biotic integrity. It is now being widely applied throughout the United States and Mexico. In the initial published version (3.0), the standard for assessing an evaluation area was the NRCS Ecological Site Description, a description of physical and biotic characteristics of land with similar soils and climate and that respond similarly to management. Multiple reference areas provided visual representations of the ecological site and were used to supplement Ecological Site Descriptions or as the standard when Ecological Site Descriptions were not available. This approach failed to integrate all of the diverse sources of information about rangeland ecological processes. In response, we developed an ecological reference sheet for version 4.0. A reference sheet is developed for each ecological site based on the integration of ecological site descriptions, expert knowledge, scientific literature and reference sites. Each sheet should be developed by a group of experts familiar with the range of variation in the soil, hydrologic and vegetation indicators. When possible, data similar to those found in ecological site descriptions should be used to generate a quantitative range of expected variation. We believe this change will increase the quality and consistency of evaluations completed with this protocol.}, author = {Jeffrey E. Herrick and D.A. Pyke and M. Pellant and P. L. Shaver} } @article {50827, title = {Night-time conductance in C3 and C4 species: Do plants lose water at night?}, journal = {Journal of Experimental Botany}, volume = {54}, number = {383}, year = {2003}, month = {February 1, 2003}, pages = {861-865}, abstract = {Significant night-time stomatal conductance and transpiration were found for 11 out of 17 species with a range of life histories (herbaceous annual, perennial grass, shrub, tree), photosynthetic pathways (C3, C4), and habitats in the western United States. Across species and habitats, higher night-time conductance and transpiration were associated with higher daytime values. The prevalence, mechanisms and ecological implications of substantial night-time water loss deserve further investigation.}, keywords = {conductance, night-time, transpiration}, url = {http://jxb.oxfordjournals.org/cgi/reprint/54/383/861?maxtoshow=\&HITS=10\&hits=10\&RESULTFORMAT=\&fulltext=Night-time+conductance\&searchid=1\&FIRSTINDEX=0\&resourcetype=HWCIT}, author = {K. A. Snyder and J. H. Richards and L.A. Donovan} } @article {50830, title = {New proposed National Resource Inventory protocols on nonfederal rangelands}, journal = {Journal of Soil and Water Conservation}, volume = {58}, number = {1}, year = {2003}, note = {Entered by other location; citation not in ARIS; duplicated by $\#$146018.}, month = {January 1, 2003}, pages = {18A-21A}, abstract = {Rangeland NRI activities in NRCS have provided scientifically credible information about status, conditions, and trends on nonfederal rangelands. The inventory process was largely qualitative in 1982, but evolved and included more quantitative field methods in 1992. Interagency efforts since 1995 have developed protocols for rangeland field inventory techniques that have been the quantitative foundation of rangeland science studies. The new proposed NRI protocols are designed to detect long-term (years to decades) changes in the condition on rangeland ecosystems, and monitor short-term impacts which may be of immediate concern. After establishing a sound field based dataset for rangeland PSUs, remote sensing and other quick assessment techniques could be used in interim periods for some indicators. The proposed NRI protocols contain a carefully planned mixture of quantitative and qualitative variables which the interagency group (NRCS, ARS, BLM, USFS, and USGS) have identified as being important {\textquestiondown}state of the art{\textquestiondown} measures of overall rangeland conditions. Field based inventories to assess plant composition, invasive and noxious weed trends, rangeland health, conservation practices applied and needed, identification of disturbances, and measures of canopy and basal plant gaps have been tested by the interagency group. Traditional NRI components such as percent similarity, apparent rangeland trend, and conservation treatment needs have been retained. In addition to the NRI objectives listed at the beginning of the paper, data from the proposed NRI field protocols could be used to further range science and provide more knowledge about interactions among environmental, soil, and plant variables, and management practices.}, url = {/files/bibliography/03-004.pdf}, author = {K. Spaeth and Frederick B. Pierson and Jeffrey E. Herrick and P. L. Shaver and D.A. Pyke and M. Pellant and Thompson, D. and R. Dayton} } @article {51014, title = {Nutrient resorption in shrubs growing by design and by default in Chihuahuan Desert arroyos}, journal = {Oecologia}, volume = {128}, number = {3}, year = {2001}, month = {August 1, 2001}, pages = {351-359}, abstract = {

In the northern stretches of the Chihuahuan Desert, the margins of ephemeral stream channels called arroyos support a unique vegetation dominated by a guild of winter-deciduous shrubs. To explore the dynamics of nutrient conservation in this assemblage of arroyo shrubs, we measured nitrogen (N) and phosphorus (P) resorption efficiency and proficiency in six species of shrubs growing in arroyos in southern New Mexico, USA. Collectively, these six species were no more efficient or proficient at resorbing N and P from senescing leaves than shrubs growing in other environments. Resorption efficiency averaged 53\% and 50\% for N and P, respectively, and resorption proficiency averaged 0.80\% and 0.06\% for N and P, respectively. However, resorption varied significantly between species specifically restricted in their distribution to riparian habitats (obligate riparian species) and those that were not. The two obligate riparian species combined (Brickellia laciniata, Chilopsis linearis) were significantly more efficient and proficient at resorbing N than the non-obligate riparian species combined (Fallugia paradoxa, Flourensia cernua, Prosopis glandulosa, Rhus microphylla). Additionally, both Brickellia and Chilopsis were individually significantly more proficient at resorbing N than any of the other four species. The dichotomy in resorption between obligate riparian species and those that were not may have been the result of the interplay between hydrology, geomorphology, and biology. Because arroyos move in space as the movement of water erodes banks and changes channel location, some plants are found along arroyos only because the arroyos have moved to them. These plants (plants growing by default) may be less well adapted to arroyo margins than obligate riparian species (plants growing by design). Significant differences in resorption between obligate and nonobligate riparian species suggested that evolutionary history and habitat specificity may be added to the list of factors known to influence resorption. Selected life history traits of the six species did not appear to be related to any measure of resorption, but leaf surface area, specific leaf mass, and nutrient concentrations in green leaves were all correlated with resorption efficiency or proficiency in one or more species. The only species capable of symbiotic N fixation, Prosopis glandulosa, retained at least 2.3 times more N in its senesced leaves than any other species. Patterns of resorption in arroyo shrubs strongly indicated that efficiency and proficiency are fundamentally different, complementary measures of resorption.

}, doi = {10.1007/s004420100668}, url = {/files/bibliography/01-056.pdf}, author = {K.T. Killingbeck and Walter G. Whitford} } @inbook {51034, title = {Non-Equilibrium Ecology}, booktitle = {Encyclopedia of Global Environmental Change, Volume Two}, year = {2001}, note = {//NONE//NONE//ProCite field[6]: In}, month = {2001}, publisher = {John Wiley \& Sons}, organization = {John Wiley \& Sons}, abstract = {One of the most controversial and well-known theories associated with global change is the Gaia hypothesis. Originated by biologist James Lovelock, this hypothesis states that over geologic time, biotic life on Earth has evolved to "control" the physical forces of nature, resulting in a bio-geosphere that is self-regulatory, or homeostatic. Thus, acting like the thermostat in your house, any deviation from this balanced condition or set-point will result in a "corrective" response in order to maintain the stable equilibrium. Do ecosystems behave this way? If so, predicting their response to global change would be relatively easy. However, notions of stable equilibria -- as espoused by the Gaia hypothesis -- are centered around the concept of the balance of nature, which has dictated western views of science since antiquity. It is ironic that the Gaia hypothesis is receiving such popular attention at a time when ecologists are eschewing the equilibrium-centered view per se in favor of a non-equilibrium one. During the past several decades ecology has experienced a paradigm shift: from the balance of nature to equilibrium/stability to non-equilibrium. This paradigm shift, which embraces spatio-temporal dynamics of ecosystems, is essential to our ability to develop a predictive understanding of the dynamics of ecosystems.}, keywords = {book, books, chapter, chapters, global change, model, model, Gaia, model, non-equilibrium ecology, report, reports}, author = {J. F. Reynolds}, editor = {Mooney, H. A. and J. Canadell} } @article {51114, title = {Nutrient losses in runoff from grassland and shrubland habitats in southern New Mexico: II. Field plots}, journal = {Biogeochemistry}, volume = {49}, year = {2000}, note = {//NMSU,USDA//LTER III//}, month = {2000}, pages = {69-86}, abstract = {

Losses of dissolved nutrients (N, P, K. Ca, Mg, Na, Cl, and SO4) in runoff were measured on grassland and shrubland plots in the Chihuahuan desert of southern New Mexico. Runoff began at a lower threshold of rainfall in shrublands than in grasslands, and the runoff coefficient averaged 18.6\% in shrubland plots over a 7-year period. In contrast, grassland plots lost 5.0 to 6.3\% of incident precipitation in runoff during a 5.5-year period. Nutrient losses from shubland plots were greater than from grassland plots, with nitrogen losses averaging 0.33 kg ha-1yr-1 vs. 0.15 kg ha-1 yr-1, respectively, during a 3-year period. The greater nutrient losses in shrublands were due to higher runoff, rather than higher nutrient concentrations in runoff. In spite of these nutrient losses in runoff, all plots showed net accumulations of most elements due to inputs from atmospheric deposition. Therefore, loss of soil nutrients by hillslope runoff cannot, by itself, account for the depletion of soil fertility associated with desertification in the Chihuahuan desert.

}, keywords = {article, articles, Bouteloua eriopoda, desertification, hydrology, Larrea tridentata, nitrogen, nutrient budgets, phosphorus, runoff, journal, journals}, doi = {10.1023/A:1006246126915}, url = {files/bibliography/JRN00307.pdf}, author = {W. H. Schlesinger and Timothy J. Ward and John P. Anderson} } @proceedings {51171, title = {Natural cycles of desertification in the Chihuahuan Desert, North America}, year = {1999}, note = {//?//LTER III//}, month = {1999}, publisher = {Texas Technological University Press}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, desertification, natural cycles, proceeding, proceedings}, author = {Curtis H. Monger} } @article {51186, title = {Nutrient losses in runoff from grassland and shrubland habitats in Southern New Mexico: I. rainfall simulation experiments}, journal = {Biogeochemistry}, volume = {45}, year = {1999}, note = {//NMSU,USDA//LTER III//}, month = {1999}, pages = {21-34}, abstract = {

Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/l) and lowest in bare plots in the shrubland (0.55 mg/l). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands -- consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.

}, keywords = {article, articles, desertification, grassland, hydrology, grassland, hydrology, nutrient export, hydrology, rainfall simulation, hydrology, shrubland, hydrology, surface runoff, journal, journals, nitrogen, nutrient budgets, phosphorus, runoff}, doi = {10.1023/A:1006020831706}, url = {files/bibliography/JRN00282.pdf}, author = {W. H. Schlesinger and Athol D. Abrahams and A.J. Parsons and John Wainwright} } @article {51262, title = {Natural asexual reproduction in fourwing saltbush Atriplex canescens (Pursh) Nutt.}, journal = {Journal of Arid Environments}, volume = {36}, year = {1997}, month = {1997}, pages = {267-270}, abstract = {

Native populations of fourwing saltbush, Atriplex canescens (Pursh) Nutt., are generally naturally seeded. Two populations were found in New Mexico that are asexually propagated by underground stems. The ratios of female to male plants in asexually produced populations differed from naturally seeded populations. This trait appears to be under genetic control and would be valuable in improving fourwing saltbush for revegetation of rangelands.

}, keywords = {reclamation, remediation, restoration, revegetation, sex expression}, url = {/files/bibliography/414.pdf}, author = {J.R. Barrow} } @article {JRN54964, title = {A New Version of the Snowmelt Runoff Model Incorporating Radiation}, journal = {The Environmental Professional }, volume = {19}, year = {1997}, pages = {109-116}, chapter = {109}, abstract = {

As a microcomputer program with modest data requirements, the Snowmelt Runoff Model (SRM) has been successfully applied to simulate and forecast runoff from seasonally snow-covered basins around the world. The existing SRM uses the Temperature Index method, a single-index equation based on daily temperature, to predict snowmelt runoff. Recent work to enhance SRM has added a second index, net radiation, to create a more flexible and physically-based version known as the Temperature/Radiation method. Both SRM versions use an index equation to compute snowmelt runoff from the snow-covered fraction of a basin, and can incorporate remotely-sensed data to determine the physical parameters required for model input. This paper compares the results of the temperature Index and Temperature/Radiation methods with observed runoff from (1) a small basin with measured net radiation, (2) a small basin with net radiation estimated form in-situ meteorological measurements, and (3) a large basin with net radiation estimated using publicly available data from on-line sources. The results show that the two versions are comparable in terms of the computed numerical measures of model performance. Therefore, the user could choose between the two methods depending upon the available data. The Radiation/Temperature method reduces the need to vary a critical model parameter throughout the season, and provides a physically-based method to estimate that parameter independent of model input.

}, url = {files/bibliography/Rango1997-01.pdf}, author = {K.L. Brubaker and A. Rango} } @article {51278, title = {The near-ubiquitous pedogenic world of mesquite roots in an arid basin floor}, journal = {Journal of Arid Environment}, volume = {35}, year = {1997}, month = {1997}, pages = {39-58}, abstract = {

A major invasion of grassland by shrubs began about 1850 A.D. in many desert areas of sourthern New Mexico. In the broad floor of the Jornada del Muerto Basin, mesquite (Prosopis glandulosa) is the most numerous of these invading shurbs. Mesquite roots in a coppice dunewere excavated and traced laterally in an area with an extremely complex soil pattern (Petrocalcids, Torripsamments, Haplargids, and Calciargids). The roots readily penetrated all soil horizons except the continuosly indurated petrocalcic horizon of the Petro clacids. However, the roots grew along the torp of the petrocalcic horizon and in places found locations for penetrationm such as cracks and pipes, with numerous, often upward-growing roots enrougte to utilize the sparse preciptation. At another study site mesquite encroached into a play dominated by Haplocalcids, in one of chich mesquite roots descended to a depth of at lease 5.5 m. Althoough thte spread of mesquite seed by cattle was a major factor in the spread of mesquite, its successful establishment over large areas was apparently due to the ability of mesquite roots to adapt to a wide variety of soils and soil conditions to take their advantage fo the sparse precipitation; to their ability to greatly proliferate while spreading laterally over long distances; to grow upward and take advantage of small precipitation events that only wet the soil to depths of a few centimeters; to descend to great depths along cracks and other openings in the soil, down which soil water also penetrates, and thus to their ability to utilize available water at all depths.

}, doi = {10.1006/jare.1996.0157}, url = {/files/bibliography/584.pdf}, author = {L. H. Gile and Gibbens, Robert P. and J.M. Lenz} } @conference {51323, title = {Nutrient content and antiquality factors in Flourensia cernua at four growth stages}, booktitle = {Journal of Animal Science}, volume = {74 (Suppl. 1)}, year = {1996}, month = {1996}, pages = {199}, abstract = {

Tarbush (Flourensia cernua \ DC) is a rapidly increasing Chihuahuan Desert shrub. Use of livestock to control tarbush is being examined. Whole plants (n=120) were harvested to assess nutrient composition during 3 years across 4 growth stages: early (EG), midpoint (MG), late (LG) and senescent (SG) growth. Plants were air-dried then leaves were removed and freeze-dried. Nitrogen concentration was greatest for EG, lowest for SG, and no different between MG and LG (P \<.05; 3.95, 2.82, 2.77 and 2.62\% of DM for EG, MG, LG, and SG, respectively. Soluble N content was greater and ADIN content was lower for EG (P\<.05) than other stages. Insoluble N declined with advancing maturity (P\<.05). As a fraction of total N, insoluble N decreased and soluble N increased with maturity (P \<.05). IVDMD and was greater for EG than the other stages (P \<.05; 66.8, 61.0, 60.5 and 60.4\% of DM for EG, MG, LG and SG, respectively. Calcium concentration increased and P content decreased with maturity (P \<.05). Concentrations of NDF and ADF were lowest for EG (P \<.05) but did not differ among later growth stages. ADL content was least for EG and less for MG than LG or SG (P \<.05). Condensed tannin content tended (P \<.10) to increase with advancing season. Total phenolics concentration was least for EG (P \<.05)and not different among the other growth stages (6.6, 8.1, 7.9 and 7.6\% of DM for EG, MG, LG and SG, respectively). Nutrients and antiquality variables exhibited patterns normally associated with advancing phenology. Across seasons and years, tarbush was of reasonably high quality (3.0 \% N, 62.2 \% IVDMD, 20.8 \% NDF, 17.0 \% ADF, 1.51 \% Ca and 0.15 \% \ P, DM basis) and low in antiquality factors (0.1 \% ADIN, 6.6 \% ADL and .34 \% condensed tannins, DM basis), with the exception of total phenolics (7.6 \% of DM) and ether extract (13.6 \% of DM).

}, author = {Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @proceedings {51376, title = {Nurse plant associations in the Chihuahuan Desert shrublands}, volume = {Gen. Tech. Rep. INT-GTR-338}, year = {1996}, note = {//NMSU//LTER III//ProCite field[6]: InProCite field[8]: Compilers}, month = {May 23-25, 1995}, pages = {158-164}, publisher = {U.S. Department of Agriculture, Forest Service, Intermountain Research Station}, address = {Las Cruces, NM}, abstract = {

Spatial studies in the Chihuahuan Desert of associations with Larrea shrub islands found juveniles more often associated with shrub islands than unassociated. The spatial structure of the shrub islands points to Nurse Plant facilitation of seedlings. Experiments tested the effects of canopy, shrub islands, and understory on five perennials{\textquoteright} germination. Longer survival times, but not higher germination, of Zinnia acerosa were found beneath artificial canopies in intershrub areas and cleared shrub islands as compared to intact shrub islands. Therefore, Zinnia may be poor competitor, preferring germination microsites with few competitors, regardless of Nurse Plant effects.

}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, germination, nurse plant, Larrea, nurse plant, Larrea, plant association, plant, nurse plant, proceeding, proceedings, seed, nurse plant, shrub, nurse plant, Zinnia, germination}, url = {files/bibliography/JRN00212.pdf}, author = {Thompson, J. and L. Huenneke}, editor = {J.R. Barrow and McArthur, E.D. and R. E. Sosebee and R. J. Tausch} } @proceedings {51382, title = {Natural methods of establishing native plants on arid rangelands}, volume = {Gen. Tech. Rep. INT-GTR-315}, year = {1995}, month = {October 19-21, 1}, pages = {44-45}, publisher = {USDA Forest Service, Intermountain Research Station, Gen. Tech. Rep. INT-GTR-315}, address = {Las Vegas, NV}, abstract = {

Desertification of native rangelands is a global problem. Mechanical and chemical approaches to remediate these lands are not universally suitable or appropriate, and often times induce disturbances that escalate rather than resolve the trend. Therefore, we are proposing to utilize natural systems such as wind, water, or animals to disperse seeds of desirable native plant species. These methods would have minimal disturbance on native landscapes. Concepts of water and animal seed dispersal on arid rangelands are discussed.

}, url = {/files/bibliography/435.pdf}, author = {J.R. Barrow and Kris Havstad}, editor = {Roundy, Bruce A. and McArthur, E. Durant and Haley, Jennifer S. and Mann, David K.} } @article {51421, title = {Noninvasive soil water content measurement using electromagnetic induction}, journal = {Water Resources Research}, volume = {31}, number = {10}, year = {1995}, note = {//NMSU//LTER-III//}, month = {1995}, pages = {2401-2409}, abstract = {

The feasibility of soil water content measurement using electromagnetic induction was investigated in an arid region of southern New Mexico. Soil water measurements were taken monthly with a neutron probe at 65 equally spaced stations along a 1950-m transect. At the same time, noninvasive electrical conductivity measurements of the soil were taken with a Geonics EM-31 ground conductivity meter. Using 16 months of measurements, we found a linear relationship exists between bulk soil electrical conductivity and total soil water content in the top 1.5 m of the profile. A simple linear regression model was developed to describe the relationship between soil water content and bulk soil electrical conductivity. The spatial and temporal accuracy of the regression model is addressed as well as the total number of neutron access tubes needed to accurately calibrate the model. By comparison with the neutron scattering method the electromagnetic induction method is quite accurate for the prediction of water content changes over time. The speed and ease of use combined with the accuracy of the measurements make the ground conductivity meter a valuable tool for rapid, noninvasive soil water measurements.

}, keywords = {article, articles, journal, journals, soil, water content, technique, electromagnetic induction, transect, soil water, water, soil}, doi = {10.1029/95WR01949}, url = {files/bibliography/JRN00191.pdf}, author = {Sheets, Keith R. and Jan M. H. Hendrickx} } @article {51581, title = {Neoformation of palygorskite in a southern New Mexico aridisol}, journal = {Soil Science Society of America Journal}, volume = {55}, number = {6}, year = {1991}, note = {//LOCAL//NONE//}, month = {1991}, pages = {1646-1650}, abstract = { Palygorskite is the dominant clay mineral in a petrocalcic horizon of the Rotura soil series (a coarse-loamy, mixed, thermic, Typic Haplargid), a soil of middle Pleistocene age in southern New Mexico. The purpose of this study was to determine if palygorskite is eolian in origin, inherited from its alluvial parent material, or neoformed in the soil. The origin of palygorskite was determined by examining clay mineral distribution, soil-water extract chemistry, and palygorskite fiber morphology. An eolian origin of palygorskite is unlikely because it is absent in upper soil horizons and no palygorskite was captured in dust traps during a 10-yr study. An inherited origin is also unlikely because palygorskite is not an inherent component of Rio Grande alluvium. Scanning electron microscopy revealed that delicate palygorskite fibers radiate perpendicularly into pore spaces, which indicates neoformation. The petrocalcic horizon may foster palygorskite neoformation because it is the site of high Mg content and abundant sand- and silt-grain dissolution.}, keywords = {article, articles, calcite, geomorphology, petrocalcic horizon, geomorphology,palygorskite formation, journal, journals, palygorskite formation, soil, palygorskite formation, soil, petrocalcic horizon}, author = {Curtis H. Monger and LeRoy A. Daugherty} } @article {51631, title = {Nitrogen loss from deserts in the southwestern United States}, journal = {Biogeochemistry}, volume = {10}, year = {1990}, note = {//OTHER//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {67-79}, abstract = {

A lower limit for nitrogen loss from desert ecosystems in the southwestern United States was estimated by comparing nitrogen inputs to the amount of nitrogen stored in desert soils and vegetation. Atmospheric input of nitrogen for the last 10,000 years was conservatively estimated to be 2.99 kg N/m2. The amount of nitrogen stored in desert soils was calculated to be 0.604 kg N/m2 using extant data from 212 profiles located in Arizona, California, Nevada, and Utah. The average amount of nitrogen stored in desert vegetation is approximately 0.036 kg N/m2. Desert conditions have existed in the southwestern United States throughout the last 10,000 years. Under such conditions, vertical leaching of nitrogen below a depth of 1 m is small (ca. 0.028 kg N/m2 over 10,000 years) and streamflow losses of nitrogen from the desert landscape are negligible. Thus, the discrepancy found between nitrogen input and storage represents the amount of nitrogen lost to the atmosphere during the last 10,000 years. Loss of nitrogen to the atmosphere was calculated to be 2.32 kg N/m2, which is 77\% of the atmospheric inputs. Processes resulting in nitrogen loss to the atmosphere from desert ecosystems include wind erosion, ammonia volatilization, nitrification, and denitrification. Our analysis cannot assess the relative importance of these processes, but each is worthy of future research efforts.

}, keywords = {article, articles, denitrification, journal, journals, nitrogen loss, soil, denitrification, soil,nitrogen loss}, doi = {10.1007/BF00000893 }, url = {files/bibliography/JRN00125.pdf}, author = {Peterjohn, William T. and W. H. Schlesinger} } @book {51674, title = {The natural history and role of subterranean termites in the northern Chihuahuan Desert}, series = {Special Biotic Relationships in the Arid Southwest}, year = {1989}, note = {//NMSU//LTER II,US-IBP//Listed in LTER3 proposal as citing LTER2 support//ProCite field[6]: In}, month = {1989}, pages = {53-77}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {

In this chapter, we summarize what is known about Gnathamitermes tubiformans include discussions on (1) population estimates, (2) diurnal and seasonal aboveground activity patterns, (3) aboveground gallery construction, (4) their importance in nitrogen cycling and the breakdown of organic matter, (5) interactions with microarthropods, (6) effects on soil infiltration rates, and (7) effects on plant communities.

}, keywords = {book, books, chapter, chapters, Gnathamitermes, report, reports, termite, decomposition, termite, gallery construction, termite, microarthropod interaction, termite, nitrogen cycling, termite, plant communities, termite, soil infiltration, termite,natural history, termite,population estimation, termites, behavior}, url = {files/bibliography/JRN00111.pdf}, author = {William P. MacKay and J. C. Zak and Walter G. Whitford}, editor = {Schmidt, Justin O. (ed.)} } @proceedings {51764, title = {Nitrogen enrichment effects on vegetation of a northern Chihuahuan Desert landscape}, volume = {General Technical Report RM-150}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//ProCite field[6]: In}, month = {October 12-16, 1}, pages = {112-116}, publisher = {USDA Forest Service, Rocky Mountain Forest and Range Experiment Station}, address = {Tucson, Arizona}, abstract = { A large scale experiment was conducted at the NSF/LTER Jornada site examining enrichment effects of a limiting resource (nitrogen) across a desert landscape. Results showed increased cover of ephemeral plant species and decreased species diversity on response to increased nitrogen, probably due to changes in availability ratios of limiting resources and decreased heterogeneity in the spatial destribution of soil nitrogen.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, nitrogen amendment, nutrient, nitrogen amendment, plant community, diversity, plant productivity,nitrogen amendment, proceeding, proceedings, transect, nitrogen amendment, vegetation, nitrogen amendment}, author = {Joe M. Cornelius and Gary L. Cunningham}, editor = {Earl F. Aldon and Carlos E. Gonzale Vicente and Moir, William H. (eds.)} } @article {51767, title = {Nitrogen mineralization in a desert soil: Interacting effects of soil moisture and nitrogen fertilizer}, journal = {Soil Science Society of America Journal}, volume = {51}, year = {1987}, note = {//NMSU//LTER I//}, month = {1987}, pages = {1033-1041}, abstract = {

The responses of N mineralization to two patterns of supplemental water, N fertilizer, and a drying-wetting episode were examined on order to evaluate the effects of variation in timing and intensity of natural precipitaion on N avialability. Field plots received either 6 mm water/week or 25 mm water/month with or without 10 g N m-2. Samples were collected three times from July 1984 to March 1985 and incubated in the lab for 28 d. The effects of drought were simulated by drying soil at 35 degrees C for 28 d followed by 168-d leaching incubations. Supplemental water reduced 28-d mineralization by 22\% in soil collected during dry and moderate soil moisture conditions (July 1984, October 1984) but had no effect on soils collected during a moist period (March 1985). Nitrogen fertilizer had no effect on 28-d mineralization in soils from July but increased 28-d mineralization by 58\% in soils from October and March. Air-drying increased mineralization rates across all field treatments during the first 14 d of the 168-d leaching incubations. Mineralization rates were lower in soils from watered plots in both the air-dry and field-moist treatments. Air-drying interacted with both the water and N treatments by increasing watering effects and decreasing feritlizer N effects. The observed drying effects appear to be a net result of several processes that, on the whole, tend to increase N availability. Mineralization rates in both experiments were lower in 6 mm/week soils than in 25 mm/month soils which, in turn, were lower than unwatered controls. We hypothesize that increased moisture availability eventually leads to losses of minerlizable N as initially rapid mineralizaiton converts organic N to inorganic forms that are readily lost from the soil.

}, keywords = {article, articles, drought,nitrogen mineralization, journal, journals, Larrea,nitrogen mineralization, nitrogen amendment,Larrea, nitrogen mineralization,Larrea, rainfall simulation,Larrea}, doi = {10.2136/sssaj1987.03615995005100040038x}, url = {files/bibliography/JRN00058.pdf}, author = {F. M. Fisher and L. W. Parker and John P. Anderson and Walter G. Whitford} } @article {51780, title = {Nutrient reabsorption efficiency and the response to phosphorus fertilization in the desert shrub Larrea tridentata}, journal = {Biogeochemistry}, volume = {4}, year = {1987}, note = {//NMSU//LTER II//}, month = {1987}, pages = {265-276}, abstract = {A field fertilization experiment demonstrated that growth of Larrea tridentata was not limited by phosphorus, even though soils contained high levels of pedogenic carbonates that can potentially fix high amounts of phosphorus. Nutrient reabsorption efficiencies in unfertilized shrubs ranges from 72-86\% for P, making nutrient reabsorption a very effective nutrient conservation mechanism. Absolute amounts of N and P reabsorption increased with N and P concentrations in leaves, with reabsorption being greater during drought stress than during rapid leaf growth. However, only N reabsorption efficiency increased with increasing plant N status. A model was developed to explain patterns of nutrient reabsorption efficiencies over large gradients in nutrient availability.}, keywords = {article, articles, ecosystem, fertilization, phosphorous amendments, journal, journals, Larrea,nutrient use, Larrea,phosphorous, nutrient reabsorption efficiency, nutrient use, phosphorous cycling}, author = {Kate Lajtha} } @article {51850, title = {Nitrate reductase activity of Kleingrass (Panicum coloratum L.) during drought in the northern Chihuahuan Desert}, journal = {Journal of Range Management}, volume = {39}, number = {6}, year = {1986}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {November 1, 1986}, pages = {531-535}, abstract = {

Plant nitrate (NO3-N) uptake rates are often low in desert environments because soil nitrogen levels are typically low, and mineralization and nitrification of nitrogen is moisture-dependent. During drought, leaf tissue NO3-N levels toxic to grazing animals can result because the enzyme responsible for NO3-N reduction (nitrate reductase; NR) is repressed during plant water stress. Seasonal leaf NR activity (in vivo), and NO3-N, total nitrogen, and leaf water (\%) content of kleingrass (Panicum coloratum L.) plants growing in situ in the northern Chihuahuan Desert were determined. Total precipitation during the April through November growing season (11.5 cm) was 40\% less than the long-term average (19 cm). This drought resulted in low NR activity, repressed plant growth, and water-stressed plants through most of the growing season. Seasonal and diurnal leaf NR activities were positively correlated (P\<.05) with leaf water contents (\%) and leaf water potentials, respectively. The latter correlation was significant only with young leaf tissue. Young leaf tissue reduced 29.6 {\textmu}mol NO3 -N {\textbullet} gDW-1 on 14 July when leaf water potentials exceeded -3.0 MPa. On 18 May, 7.1{\textmu}mol NO3-N {\textbullet} gDW-1 were reduced when older leaf tissue was present and leaf water potentials did not exceed -3.0 MPa. Leaf NO3-N accumulated to levels toxic to livestock during August, September, and October. The stem plus leaf sheath component of the aboveground biomass was the primary site for NR activity, and nitrogen and biomass allocation during 6 phenological stages (second through fifth leaf stages, and boot and immature seed stages). Immature seeds comprised only 12.3\% of the aboveground biomass and possessed 29.9\% of the nitrogen and 62.2\% of the total capacity of NO3-N reduction.

}, url = {/files/bibliography/301.pdf}, author = {Ray, I.M. and Sisson, W.B.} } @article {51902, title = {New Mexico State University College Ranch and Jornada Experimental Range: a summary of research 1900-1983}, year = {1984}, note = {//NMSU,USDA//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1984}, address = {New Mexico Agricultural Experiment Station}, abstract = {

In 1982, the New Mexico State University College Ranch became the site of a Long Term Ecological Research (LTER) project, funded by the National Science Foundation. The interdisciplinary nature of the project and the potential for extensive cooperation with non-resident investigators illuminated a need for a comprehensive indexing of published research conducted at the College Ranch and the adjoining USDA Jornada Experimental Range. The resulting synthesis features a brief narrative history and outline of research, providing information for both technical and non- technical readers, and a bibliography and associated keyword-citation index designed as references in research pursuits.

}, keywords = {bibliography,Jornada research, book, books, chapter, chapters, history,Jornada research, Jornada,bibliography, report, reports}, isbn = {Special Report 56}, url = {/files/bibliography/056.pdf}, author = {Marsha R. Conley and W.H. Conley} } @mastersthesis {51953, title = {Nutritional value of cattle diets on continuously and seasonally grazed semidesert range}, year = {1983}, note = {//??//NONE//}, month = {1983}, pages = {48}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle grazing,diet, cattle grazing,nutrition, dissertation, dissertations, range mangement, theses, thesis}, author = {Hinojosa, Juan Antonio} } @mastersthesis {51967, title = {Nesting ecology and diet of Swainson{\textquoteright}s hawk in the Chihuahuan Desert, south-central New Mexico}, year = {1983}, note = {//USDA//NONE//}, month = {1983}, pages = {30}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {

This thesis reports the density, reproductive chronology, nesting success, and diet of Swainson\&$\#$39;s Hawk (Buteo swainsoni) in the Chihuahuan Desert grasslands of south-central New Mexico during 1974 and 1975. The average density for both years was one pair per 9.45 km2. The mean laying date for 1974 was May 5 and was May 6 in 1975. The mean hatching date for both years was June 11. Clutch sizes ranged from two to four eggs with the average clutch size for the combined years being 2.8 eggs. The combined mean number of fledglings per nest was 1.6. This fledging rate is similar to other studies. A total of 522 prey items were identified in these samples; items represented 21 different species, which is the greatest variety of prey reported for Swainson\&$\#$39;s Hawk.

}, keywords = {bird,Buteo, bird,diet, bird,nesting ecology, dissertation, dissertations, Swainson{\textquoteright}s hawk,diet, Swainson{\textquoteright}s hawk,nesting ecology, theses, thesis}, url = {files/bibliography/83-Thesis-W.R.Piltz_.pdf}, author = {Pilz, Wayne R.} } @article {52029, title = {A new concept in assessing cotton pollen germinability}, journal = {Crop Science}, volume = {21}, year = {1981}, month = {May-June 1981}, pages = {441-443}, keywords = {cotton, germinability, pollen}, url = {/files/bibliography/99-009.pdf}, author = {J.R. Barrow} } @article {52053, title = {Nutrient cycling by the subterranean termite Gnathamitermes tubiformans in Chihuahuan Desert ecosystem}, journal = {Oecologia}, volume = {48}, year = {1981}, note = {//NMSU//US-IBP//}, month = {1981}, pages = {277-283}, abstract = {

We estimated the density of subterranean termites Gnathamitermes tubiformans at 800,000 ha-1 for a standing crop biomass of 2 kg ha-1. Predation losses were estimated to be 5.73 kg ha-1 yr-1 representing the major release of nutrients from termites to surficial soil layers. Nutrient fluxes from termites to predators amounted to 410 g N ha-1 yr-1, 33 g S ha-1 yr-1 and 19 g P ha-1 yr-1. These fluxes account for 8\% of the litter N, 1.5\% of the litter P and 2.9\% of the litter S. The termites fixed an estimated 66 g ha-1 yr-1 atmospheric N and returned an estimated 100 g ha-1 yr-1 in the surface gallery carton. Since losses of elements from subterranean termites were greater than standing crops, we estimated an annual turnover of N at 3.5 times per year, P of 2.5 times per year, and S of 2.5 per times per year. Since surface foraging, predation and alate flights are pulse regulated by rainfall, nutrient flows through subterranean termites are episodic and releases of nutrients accumulated in termite biomass preceeds or is coincident with productivity \"pulses\" of some shallow rooted plants. We propose that subterranean termites are important as regulators in desert nutrient cycles.

}, keywords = {article, articles, decomposition, termites, Gnathamitermes,nutrient cycling, journal, journals, nutrient cycling, nitrogen, nutrient cycling, phosphorus, nutrient cycling, sulfur, nutrient cycling,termite, termite,nutrient cycling}, doi = {10.1007/BF00347977}, url = {files/bibliography/81-Oecologia-Whitford.pdf}, author = {Douglas Schaefer and Walter G. Whitford} } @mastersthesis {52097, title = {Nutrient aspect of optimal foraging behavior}, year = {1980}, note = {//OTHER//NONE//}, month = {1980}, pages = {37}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {When tested under field conditions, the workers of colonies of the harvester an Pogonomyrmex occidentalis will differentially recruit to patches of diet that are equal in caloric value but differ in nutrient quality. The patches of diet presented to the colonies consisted of artificial "seeds" that varied in the percent protein composition.... The results of these experiments suggest that optimal foraging models based solely on energetic considerations may be too simplistic. I suggest a generalization of Charnov{\textquoteright}s 1976 model that would allow the inclusion of nutrient components and other factors such as water content or toxin concentrations within the model. Such a model should be of greater predictive value than a model based on energetics alone.}, keywords = {ant,foraging behavior, ant,harvester ant, ant,nutrients, dissertation, dissertations, foraging behavior, model, Charkov, model,ant foraging behavior, nutrient,ants, Pogonomyrmex,foraging behavior, theses, thesis}, author = {Robert Repass} } @mastersthesis {52102, title = {Nutrient cycling by the subterranean termite Gnathamitermes tubiformans on a desert bajada}, year = {1980}, note = {//NMSU//US-IBP//}, month = {1980}, pages = {68}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Termites fulfill a unique role among social insects in desert ecosystems because of their ability to utilize cellulose. Their effect on nutrient cycles was examined. Since the flux of nitrogen through termite colonies is greater than the amount present as termite biomass, this element "turns over" about 3 1/2 times annually in termite colonies. The perennial shrub nitrogen "turns over" in 9.4 years, the litter in 2.8 years, and the annual forbs and grass component in 1 year. Phosphorus "turns over" 2.5 times annually in termite colonies, in 12.6 years in perennial shrubs, 5.8 years in dead plant litter and in 1 year in annual forbs and grasses. Sulfur "turns over" 2.5 times annually in termite colonies, in 13.0 years in perennial shrubs, 2.4 years in dead plant litter and in 1 year in annual forbs and grasses.}, keywords = {decomposition, termites, dissertation, dissertations, Gnathamitermes,nutrient cycling, nutrient cycling, nitrogen, nutrient cycling, phosphorus, nutrient cycling, sulfur, nutrient cycling,termite, termite,nutrient cycling, theses, thesis}, author = {Douglas Schaefer} } @article {52127, title = {A net CO2 exchange model for Larrea tridentata}, journal = {Photosynthetica}, volume = {13}, number = {3}, year = {1979}, note = {//LOCAL//NONE//}, month = {1979}, pages = {279-286}, abstract = {A net CO2 exchange model for the warm desert evergreen perennial Larrea tridentata (DC) Cov. (creosotebush) was developed using the modeling approach of REED et al. (1976) for the temperate deciduous tree Liriodendron tulipifera L. The approach was very successful using gas exchange measurements on environment chamber-grown Larrea tridentata and hence this approach may have side applicability and versatility for photosynthesis modeling.}, keywords = {article, articles, carbon dioxide exchange, journal, journals, Larrea, Larrea,physiology, Larrea,phytosynthesis, model, photosynthesis, Larrea, model,carbon dioxide, model,Larrea, photosynthesis,Larrea}, author = {J. F. Reynolds and Gary L. Cunningham and J. P. Syvertsen} } @mastersthesis {52187, title = {Nutritive evaluations of forage grazed from semidesert rangeland with assessment of seasonal trends and effects of dietary supplements}, year = {1977}, note = {//??//NONE//}, month = {1977}, pages = {62}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle grazing, nutrition, cattle grazing, supplements, dissertation, dissertations, theses, thesis}, author = {Lopez Trujillo, R.} } @article {52264, title = {A net CO2 exchange model for C4-grasses}, journal = {Photosynthetica}, volume = {8}, year = {1974}, note = {//NMSU//US-IBP//}, month = {1974}, pages = {28-33}, abstract = {A mathematical model was developed for predicting net CO2 exchange rates of grasses with C4-dicarboxylic acid pathway of CO2 reduction. Model coefficients for two Chihuahuan desert playa species were determined. This was done using net CO2 exchange rate data and an intrinsically non-linear regression algorithm.}, keywords = {article, articles, carbon dioxide, C4 grasses, grass, carbon dioxide, C4 grasses, grass, Hilaria, CO2 exchange, grass, Panicum, CO2 exchange, journal, journals, model, CO2 exchange, C4 grasses, photosynthesis,CO2 exchange model}, author = {Gary L. Cunningham and F. R. Balding and J. P. Syvertsen} } @article {52317, title = {Nearest neighbors in herbivorous ant colonies}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Utah State University}, address = {Logan, Utah}, keywords = {ant colonies, book, books, chapter, chapters, herbivory,ants, report, reports}, isbn = {Research Memorandum 73-32}, author = {Walter G. Whitford} } @mastersthesis {52405, title = {Nitrogen transformations in a desert grassland soil}, year = {1970}, note = {//NMSU//NONE//}, month = {1970}, pages = {50}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Nitrogen mineralization and immobilization in a desert soil were investigated. Soils were amended with protein, protein plus glucose, or ammonium chloride plus glucose, and changes occurring in the nitrogenous substrates were noted. The primary end product of nitrogen mineralization was found to be ammonia. Amino acid-nitrogen was detected in small quantities in all three soil treatments, and the formation of free amino acids in soil appears to be correlated with microbial activity. At no time during the investigations was nitrate or nitrite-nitrogen detected. Indications were that protein was degraded to amino acids which were immediately deaminated, releasing ammonia to be either used in microbial biosynthesis, absorbed by the soil complex, or to diffuse out of the soil into the atmosphere. It appeared that the largest part of the protein-nitrogen was lost from the soil as volatile ammonia, and reasons for this are discussed. A cultivated plant, Phaseolus vulgaris L., was studied to determine the nitrogen source assimilated most readily. This was found to be nitrate-nitrogen and could be substituted by amino acids in this plant.}, keywords = {biochemistry,nitrogen, dissertation, dissertations, metabolism, soil nitrogen, microbial transformation, soil nitrogen, nitrogen immobilization, nitrogen mineralization, soil, biochemistry, theses, thesis}, author = {Woods, Donald Eugene} } @proceedings {52414, title = {Notes on the geomorphology and late cenozic geology of northwestern Chihuahua}, volume = {20th Field Conference}, year = {1969}, note = {//LOCAL//NONE//ProCite field[6]: In}, month = {1969}, pages = {131-142}, publisher = {New Mexico Bureau of Mines and Mineral Resources}, abstract = {

The geomorphology and late Cenozoic geology of a 71,500 square kilometer (27,600 square mile) area of northwestern Chihuahua and adjacent parts of Sonora, New Mexico and Texas are discussed. Emphasis is on description of three major physiographic units: The Sierra Madre Occidental, and two subsections of Mexican Basin and Range section. Formal names are proposed for the latter two subdivisions. The larger unit is characterized by broad desert basins and isolated ranges of northern and eastern Chihuahua and is designated the Bolson Subsection. The higher unit, designated the Babicora-Bustillos subsection, occupies a region that is transitional, in terms of terrain and geologic features, between the Bolson unit and the Sierra Madre. Physiographic boundaries were selected on the basis of study of recently-compiled 1:250,000 scale topographic maps and some field work. Control in the northern part of the area was also provided by photos taken from Apollo and Gemini spacecraft. Studies of basin- and valley-fill geology and geomorphology in the New Mexico-Chihuahua border region since 1950 have resulted in considerable elaboration of basic concepts of the late Cenozoic landscape evolution developed notably by Hill, Lee, Baker, Bryan and P. B. King. The fundamental concept of mid- to late Tertiary and Quaternary development and filling of intermontane basins, followed by local establishment of the entrenched Rio Grande Valley system during mid- to late Pleistocene time, appears to be generally applicable to the Basin and Range area under discussion. The important influence of a cyclic climatic change during the Quaternary period on landscape evolution is also recognized.

}, keywords = {abstract, abstracts, Cenozoic geology, conference, conference proceedings, conferences, Desert Project, geomorphology, landscape evolution, proceeding, proceedings, soil}, author = {J. Hawley} } @article {52545, title = {The nordihydroguairetic acid content of the creosotebush}, year = {1949}, note = {//??//NONE//}, month = {1949}, institution = {New Mexico Agricultural Experiment Station}, keywords = {biochemistry, Larrea, book, books, chapter, chapters, Larrea,biochemistry, report, reports}, isbn = {Bulletin 349}, author = {Botkin, C. W. and Duisberg, P. C.} } @article {52549, title = {New grass for old}, journal = {American Cattle Producer}, volume = {30}, year = {1948}, month = {August 1948}, pages = {30-31}, abstract = {Is there a stockman who has not longed for an early spring and plenty of green forage? This natural sentiment is easily accounted for. When the new grass starts to grow early in the season, the cattleman has a glorious feeling that he is "over the hump" and headed for a good year. It means a greater flow of milk for the young, bigger calves and more of them and greater gains in weight and tone for the older animals. How to obtain earlier forage growth and more of it in the critical spring months has occupied the mind of many range operators. Too often the answer arrived at has been "more rain." Rainfall and warm sunshine, however, is only a part of the answer. The unimpaired capacities of the plants and soil for rapid growth are things that also must be considered. A rancher correspondent of the Hereford Journal put his finger squarely on the key to the rest of the solution when he wrote the following: "The hills are all green and where there was some old feed there is new grass for the cattle to eat." Why this difference in the rate of new growth? The answer is that the soil and vegetation that grows thereon must not be overused. Each must be allowed to restore the elements of fertility and to maintain a balance between their outgo and their replacement; otherwise production and efficiency go down. The soil and the vegetation are renewed, conditioned, and feed upon the residue of dead vegetation, namely, the "old grass" which -grew in previous years. As always, nature demands her share. When these demands are fairly met the operator has in effect exchanged old grass for new.}, keywords = {difference in rate of new growth, earlier forage growth, old grass, renewed}, url = {/files/bibliography/069.pdf}, author = {Canfield, R.H.} } @article {52554, title = {Nonprotein and carotene as an index of plant activity in range forage}, journal = {Journal of Agricultural Research}, volume = {75}, year = {1947}, note = {//??//NONE//(New Mexico Agr. Experiment Station Journal Article 45)}, month = {1947}, pages = {63-69}, keywords = {article, articles, biochemistry,carotene, biochemistry,nonprotein, journal, journals, nutrients,carotene, nutrients,nonprotein, range forage,biochemistry}, author = {Watkins, W. E.} } @article {52575, title = {Noxious range plants as soil robbers}, journal = {American Hereford Journal}, volume = {32}, number = {17}, year = {1942}, note = {//??//NONE//}, month = {1942}, pages = {118-119}, keywords = {article, articles, journal, journals, management,noxious plants, plants, noxious, toxicity, range plants}, author = {Parker, K. W.} }