@proceedings {JRN55419, title = {The economic costs of wind erosion in the United States}, year = {2022}, month = {12-9 to14-2022}, address = {Chicago, IL}, abstract = {Wind erosion negatively impacts many aspects of society, but its socioeconomic costs in the United States were last assessed comprehensively during the 1990s. It has been over three decades since and both the climate and society have changed greatly. Solar panel and wind turbine usage have risen drastically, and an infectious disease known as Valley fever that is linked to soil (and thus likely dust) has been growing in incidence. Windblown dust has also caused an increase in transportation fatalities. Due to these and other changes, we decided to re-assess the previous estimate of $10 billion annual cost of wind erosion from Pimentel et al. (1995). We examined existing literature on past cost estimates and used domestic research data when possible. Some cost estimates, such as dust morbidity, were directly taken from past studies and adjusted for inflation if necessary. Other estimates, such as loss estimates from renewable energy generation, Valley fever, and transportation costs were built from the ground up. Values for energy generation, Valley fever cases, and transportation costs were drawn from their respective government sources, such as the Department of Energy, the Centers for Disease Control and Prevention, and the Department of Transportation. The data were then modified by findings from other studies (i.e. percentage of loss attributed to dust), enabling total costs to be calculated with the cost per increment, such as the cost of one KWh of wind energy or the cost per motor vehicle crash. We found that with the most conservative parameters, windblown dust cost the U.S. at least $69 billion in the year 2017. This $69 billion estimate is likely an underestimate as other factors were not accounted for, such as airport delays and increased desertification. This study serves as an updated baseline estimate for the cost of wind erosion, but further detailed research needs to be conducted to create a more complete cost estimate for the United States. }, keywords = {economic costs, renewable energy, society, solar panel, turbine, valley fever, wind erosion}, author = {Irene Feng and Daniel Tong and Thomas E. Gill and Scott Van Pelt and Nicholas Webb} } @proceedings {JRN55361, title = {Oryx (Oryx gazella gazella) presence patterns in a long term grazing study in the Chihuahuan Desert of New Mexico}, year = {2022}, month = {2/8/2022}, abstract = {A long term grazing study comparing the impact of grazing heritage (Raramuri Criollo) vs. commercial (Brangus) beef cattle on desert rangelands was initiated in 2020 at the NMSU Chihuahuan Desert Rangeland Research Center (CDRRC). South African oryx (Oryx gazella gazella) were introduced in the 1970s onto White Sands Missile Range, located ca. 20 miles east of the CDRRC, and oryx are frequently observed in our 5,000 ha study pastures. However, patterns of oryx presence in the grazing experiment pastures have not been determined. Hence, we sought to quantify oryx presence in our study pastures to help clarify: a) their potential impact on our experiment treatments; and b) cattle-, vegetation-, season- and ranch infrastructure- related factors associated with patterns of oryx presence in our experimental pastures. We obtained ca. 2,250 images from 40 trail cameras located in our four study pastures (10 cameras/pasture). Images were collected over a nine month phase repeated in two consecutive years, 2020 and 2021. Annually, images were collected during 3 periods: a) pre-grazing (Dec{\textendash}Feb), three months prior to placing cattle in the experiment area; b) grazing, when cattle grazed the experiment pastures (Mar{\textendash}May); and c) post-grazing, the three months after cattle were removed from pastures (Jun{\textendash}Aug). Grazing occurred in pastures only in 2020; no grazing occurred in 2021 because of severe drought conditions. These data will be compared with fecal pellet counts observed on permanent 100m transects at the camera locations to corroborate relative oryx presence. Additionally, vegetation cover data were collected at the permanent transects to determine potential relationships between oryx presence and plant cover. Our poster will report on oryx presence patterns across our study pastures with respect to cattle presence, vegetation, ranch infrastructure (distance to roads and drinkers), and season of the year. }, keywords = {Chihuahuan Desert, grazing study, long term, New Mexico, Oryx, Oryx gazella gazella, patterns, presence}, author = {M. Funk and Matthew M. McIntosh and Bender, L. and Andr{\'e}s F. Cibils and Andrew Cox and Fuentes-Soriano, S. and S. Spiegal and Richard E. Estell} } @conference {JRN55315, title = {Historical shifts in United States manuresheds}, booktitle = {ASA-CSSA-SSSA Annual Meeting Abstracts}, year = {2020}, month = {11/13/2020}, abstract = {Manuresheds, a term concerned with the balance of manure availability for agricultural lands surrounding animal feeding operations, are important to achieve optimal nutrient recycling to promote sustainable agriculture systems. Spatial analytics focused on manuresheds provide locations of nutrient sources/sinks in regards to manure production versus agricultural land needs at a given spatial scale. These spatial analytics have been analyzed at numerous spatial scales (i.e. national, county level, etc.), but have yet to be subject to national level spatio-temporal analytics. Spatio-temporal analytics focused on the redistribution of manure-based nutrients (phosphorus and nitrogen) at the county-level will provide information regarding portions of the U.S. experiencing growth/shrinking of source (overabundance of nutrients for given agricultural lands) and sink (requires more nutrients to meet agricultural land needs) hotspots. Thus, this research aims to apply spatio-temporal manureshed analytics for years 1987 to 2017 across 3,109 counties. This retrospective approach will establish an understanding of the national-scale patterns of manuresheds that will better inform future needs for nutrient management. Understanding these spatio-temporal patterns will provide focus areas in which sustainable agricultural systems can be improved.}, keywords = {analytics, historical shifts, manureshed, spatio-temporal, United States manuresheds}, author = {Colton K Flynn and S. Spiegal and Douglas Smith and Peter J. A. Kleinman} } @article {JRN55141, title = {Drought suppresses soil predators and promotes root herbivores in mesic, but not in xeric grasslands}, journal = {Proceedings of the National Academy of Sciences}, volume = {116}, year = {2019}, pages = {12883{\textendash}12888}, abstract = {

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

}, issn = {0027-8424}, doi = {10.1073/pnas.1900572116}, url = {files/bibliography/Francoetal2019.pdf}, author = {A. C. Franco and Laureano A. Gherardi and Cecilia M. de Tomasel and Andriuzzi, Walter S. and Ankrom, Katharine E. and Shaw, E. Ashley and Bach, Elizabeth M. and O. E. Sala and D.H. Wall} } @article {JRN55130, title = {Data jams: Promoting data literacy and science engagement while encouraging creativity}, journal = {Science Teacher}, year = {2018}, month = {08/2018}, pages = {48-53}, chapter = {48}, abstract = {

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

}, url = {files/bibliography/18-027.pdf}, author = {Michelle Forster and Stephanie Bestelmeyer and Noelia Baez-Rodriguez and Alan Berkowitz and Bess Caplan and Rhea Esposito and Grace, Elizabeth and Steven McGee} } @proceedings {JRN54861, title = {Coordinating a national rangeland monitoring training program: Success and lessons learned}, volume = {January 28-February 2, 2018}, year = {2018}, month = {01/28/2018}, publisher = {Society for Range Management Meeting Proceedings}, address = {Reno, NV}, abstract = {

One of the best ways to ensure quality of information gathered in a rangeland monitoring program is through a strong and uniform set of trainings. Curriculum development and delivery of monitoring trainings poses unique challenges that are not seen in academic settings. Participants come from a range of educational and experience backgrounds. Additionally, participants may only have the period of the training to receive the necessary instruction before fully implementing the protocol as part of their job duties. Consequently, careful consideration for content delivery and hands on learning activities is critical for active learning. We present the lessons learned from the Bureau of Land Management{\textquoteright}s Assessment Inventory and Monitoring (AIM) training program with the partnership of USDA-ARS Jornada Experimental Range. The successes and lessons were developed from web-based and in-person trainings targeting BLM staff, seasonal staff, non-profit organizations, and academic partners for topics relating to data collection, analysis, database use and more. Consideration was given to the identification and education of both the target audience and the potential non-target audiences while taking into account the unique needs of adult learners. The AIM program has formatted training curriculum that addresses the needs of spatial, auditory, linguistic and kinesthetic learners. Challenges that impact training quality such as inconsistency in staff availability, a seasonal workforce, timing of data needs, phenology, and funding were also factored into the development of the training program. The importance of forming a training cadre and what factors should be assessed in this process has been an additional consideration. The final portion of the process was to review the most effective methods for assessing success. The training program of AIM is continually evolving, building on the success and lessons learned of the past to provide high quality information for rangeland management.

}, author = {Baili Foster and Sarah McCord and Emily Kachergis} } @article {JRN55183, title = {Measurement of Soil Color: A Comparison Between Smartphone Camera and the Munsell Color Charts}, journal = {Soil Science Society of America Journal}, volume = {81}, year = {2017}, month = {September 7 2017}, pages = {1139-1146}, abstract = {

Soil color is one of the most useful soil properties for assessing and monitoring soil health. Here we present results of tests of a new soil color app for mobile phones. Various smartphone cameras (SPCs) were tested under sunny and cloudy conditions and compared with visual estimates using Munsell color charts (MCCs). The measured and estimated soil colors were then compared with the {\textquotedblleft}true{\textquotedblright} colors determined using a spectrophotometer. The results indicated that soil color determinations based on SPC measurements under both sunny and cloudy conditions were as good as those obtained using the MCCs. The accuracy of the SPC measurements was affected by the natural illumination conditions, with higher accuracy in the sun than where clouds were present. Our results also indicated that the SPC measurements completed in the sun provide higher precision (lower variance) than SPC measurements completed under cloudy conditions or estimates based on MCCs. These results suggest that mobile-device cameras have great potential to allow non{\textendash}soil scientists, and others lacking access to color charts, to determine soil color.

}, keywords = {CIE, International Commission on Illumination, MMC, Munsell color chart; sRGB, smartphone camera, SPC, standard red-green-blue color space}, doi = {10.2136/sssaj2017.01.0009 }, url = {files/bibliography/17-036.pdf}, author = {Zhoasheng Fan and Jeffrey E. Herrick and R. Saltzman and Christina Matteis and Anna Yudina and Nicholas Nocella and Edward Crawford and Rick Parker and Justin Van Zee} } @article {JRN54629, title = {Global-change drivers of ecosystem functioning modulated by natural variability and saturating responses}, journal = {Global Change Biology}, volume = {23}, year = {2017}, pages = {503-511}, abstract = {

Humans are altering global environment at an unprecedented rate through changes in biodiversity, climate, nitrogen cycle, and land use. To address their effects on ecosystem functioning, experiments most frequently explore one driver at a time and control as many confounding factors as possible. Yet, which driver exerts the largest influence on ecosystem functioning and whether their relative importance changes among systems remain unclear. We analyzed experiments in the Patagonian steppe that evaluated the aboveground net primary production (ANPP) response to manipulated gradients of species richness, precipitation, temperature, nitrogen fertilization (N), and grazing intensity. We compared the effect on ANPP relative to ambient conditions considering intensity and direction of manipulations for each driver. The ranking of responses to drivers with comparable manipulation intensity was as follows: biodiversity\>grazing\>precipitation\>N. For a similar intensity of manipulation, the effect of biodiversity loss was 4.0, 3.6, and 1.5, times larger than N deposition, decreased precipitation, and increased grazing intensity. We interpreted our results considering two hypotheses. First, the response of ANPP to changes in precipitation and biodiversity is saturating, so we expected larger effects when the driver was reduced, relative to ambient conditions, than when it was increased. Experimental manipulations that reduced ambient levels had larger effects than those that increased them. Second, the sensitivity of ANPP to each driver is inversely related to the natural variability of the driver. In Patagonia, the ranking of natural variability of drivers is as follows: precipitation\>grazing\>temperature\>biodiversity\> N. So, in general, the ecosystem was most sensitive to drivers that varied the least. Comparable results from Cedar Creek (MN) support both hypotheses and suggest that sensitivity to drivers varies among ecosystem types. Given the importance of understanding ecosystem sensitivity to predict global-change impacts, it is necessary to design new experiments located in regions with contrasting natural variability and that include the full range of drivers.

}, keywords = {ANPP, biodiversity loss, climate change, ecosystem sensitivity, land-use change, nitrogen deposition}, doi = {10.1111/gcb.13441}, url = {files/bibliography/JRN00656.pdf}, author = {P. Flombaum and Laura Yahdjian and O. E. Sala} } @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 {JRN54392, title = {Linked hydrologic and social systems that support resilience of traditional irrigation communities}, journal = {Hydrology and Earth System Sciences}, volume = {19}, year = {2015}, month = {01/2015}, pages = {293-307}, chapter = {293}, abstract = {

Southwestern US irrigated landscapes are facing upheaval due to water scarcity and land use conversion associated with climate change, population growth, and changing economics. In the traditionally irrigated valleys of northern New Mexico, these stresses, as well as instances of community longevity in the face of these stresses, are apparent. Human systems have interacted with hydrologic processes over the last 400 years in river-fed irrigated valleys to create linked systems. In this study, we ask if concurrent data from multiple disciplines could show that human-adapted hydrologic and socioeconomic systems have created conditions for resilience. Various types of resiliencies are evident in the communities. Traditional local knowledge about the hydrosocial cycle of community water management and ability to adopt new water management practices is a key response to disturbances such as low water supply from drought. Livestock producers have retained their irrigated land by adapting: changing from sheep to cattle and securing income from outside their livestock operations. Labor-intensive crops decreased as off-farm employment opportunities became available. Hydrologic resilience of the system can be affected by both human and natural elements. We find, for example, that there are multiple hydrologic benefits of traditional irrigation system water seepage: it recharges the groundwater that recharges rivers, supports threatened biodiversity by maintaining riparian vegetation, and ameliorates impacts of climate change by prolonging streamflow hydrographs. Human decisions to transfer water out of agriculture or change irrigation management, as well as natural changes such as long-term drought or climate change, can result in reduced seepage and the benefits it provides. We have worked with the communities to translate the multidisciplinary dimensions of these systems into a common language of causal loop diagrams, which form the basis for modeling future scenarios to identify thresholds and tipping points of sustainability. Early indications are that these systems, though not immune to upheaval, have astonishing resilience.

}, doi = {10.5194/hess-19-293-2015}, url = {/files/bibliography/15-016.pdf}, author = {Alexander Fernald and Guldan, Steve and Ken Boykin and Andr{\'e}s F. Cibils and Gonzalez, M. and Hurd, B. and Lopez, S. and Carlos Ochoa and Melchor Ortiz and Rivera, J. and Rodriguez, S. and Caitriana Steele} } @article {JRN52695, title = {Interactions among resource partitioning, sampling effect, and facilitation on the biodiversity effect: a modeling approach}, journal = {Oecologia}, volume = {174}, year = {2014}, pages = {559-566}, abstract = {

Resource partitioning, facilitation, and sampling effect are the three mechanisms behind the biodiversity effect, which is depicted usually as the effect of plantspecies richness on aboveground net primary production. These mechanisms operate simultaneously but their relative importance and interactions are difficult to unravel experimentally. Thus, niche differentiation and facilitation have been lumped together and separated from the sampling effect. Here, we propose three hypotheses about interactions among the three mechanisms and test them using a simulation model. The model simulated water movement through soil and vegetation, and net primary production mimicking the Patagonian steppe. Using the model, we created grass and shrub monocultures and mixtures, controlled root overlap and grass water-use efficiency (WUE) to simulate gradients of biodiversity, resource partitioning and facilitation. The presence of shrubs facilitated grass growth by increasing its WUE and in turn increased the sampling effect, whereas root overlap (resource partitioning) had, on average, no effect on sampling effect. Interestingly, resource partitioning and facilitation interacted so the effect of facilitation on sampling effect decreased as resource partitioning increased. Sampling effect was enhanced by the difference between the two functional groups in their efficiency in using resources. Morphological and physiological differences make one group outperform the other; once these differences were established further differences did not enhance the sampling effect. In addition, grass WUE and root overlap positively influence the biodiversity effect but showed no interactions.

}, keywords = {biodiversity and ecosystem functioning, facilitation, model, net primary production model, NPP model, Patagonian steppe, resource partitioning, sampling effect, water movement}, issn = {0029-8549}, doi = {10.1007/s00442-013-2775-8 }, url = {files/bibliography/JRN00627.pdf}, author = {P. Flombaum and O. E. Sala and E. B. Rastetter} } @article {49944, title = {The ecology of dust}, journal = {Frontiers in Ecology and the Environment}, volume = {8}, year = {2011}, pages = {423-430}, abstract = {Wind erosion and associated dust emissions play a fundamental role in many ecological processes and provide important biogeochemical connectivity at scales ranging from individual plants up to the entire globe. Yet, most ecological studies do not explicitly consider dust-driven processes, perhaps because most relevant research on aeolian (wind-driven) processes has been presented in a geosciences rather than an ecological context. To bridge this disciplinary gap, we provide a general overview of the ecological importance of dust, examine complex interactions between wind erosion and ecosystem dynamics from the scale of plants and surrounding space to regional and global scales, and highlight specific examples of how disturbance affects these interactions and their consequences. It is likely that changes in climate and intensification of land use will lead to increased dust production from many drylands. To address these issues, environmental scientists, land managers, and policy makers need to consider wind erosion and dust emissions more explicitly in resource management decisions.}, keywords = {aeolian processes, biogeochemistry, climate change, disturbance, drylands, dust, dust emissions, dust flux, ecological processes, ecosystem dynamics, land use, resource management, wind erosion}, doi = {10.1890/090050}, author = {J. P. Field and Jayne Belnap and David D. Breshears and J. Neff and Gregory S. Okin and J. J. Whicker and Painter, T. H. and S. Ravi and Reheis, M. C. and Reynolds, R. L.} } @article {49945, title = {The association of land cover with aeolian sediment production at Jornada Basin, New Mexico, USA}, journal = {Aeolian Research}, volume = {3}, year = {2011}, pages = {55-66}, abstract = {

We investigated amounts and particle size distributions (PSDs) of aeolian sediments collected at five heights in five ecosystem types at the Jornada Basin, Chihuahuan Desert, New Mexico, USA. Particle size distributions, mass fluxes, and percent of dust-sized (650 lm) mass flux were determined for all heights and all ecosystem types. Differences between sites were determined using ANOVA followed by Tukey{\textendash}Kramer post hoc tests to find groupings. For creosote shrublands, grasslands, and two tarbush-dominated alluvial flats, samples collected at 5, 10, and 20 cm had \>80\% sand-sized (\>50 lm) particles, while one playa and tarbush site yielded ~45\% dust-sized particles at 5 and 10 cm. The transition from saltation to suspension was ~20 cm for most sites. Two mesquite dune sites and an anthropogenically devegetated site, all with high overall mass fluxes, shifted to suspension at ~50 cm. Highest dust fluxes occurred at the devegetated site, followed by the playa, a mesquite site with unvegetated {\textquoteleft}{\textquoteleft}streets,{\textquoteright}{\textquoteright} and tarbush sites.
These field observations are consistent with laboratory-based dust emission experiments and remote sensing studies in the Chihuahuan Desert. Playas and tarbush sites are major dust producers due to high proportions of fines, whereas the mesquite site produces much dust because of greater overall mass flux. Mesquite dunes covering most of the basin likely produce the most dust overall, though playas and tarbush-
dominated alluvial flats (which cover about 8\%) can emit large amounts of dust. Continuing shrubland encroachment will likely increase dust emissions from the Jornada Basin, as well as in other arid regions. {\textcopyright} 2011 Elsevier B.V. All rights reserved.10.1016/j.aeolia.2011.02.002

}, keywords = {BSNE, Chihuahuan Desert, dust collection, dust flux, Jornada Basin LTER, land cover, NPP sites, particle size, sand transport, vegetation communities}, doi = {10.1016/j.aeolia.2011.02.002}, url = {files/bibliography/JRN00587.pdf}, author = {Floyd, Kevin W. and Thomas E. Gill} } @conference {JRN54493, title = {Mesquite: A long view}, booktitle = {16th Biennial Mogollon Archeology Conference}, year = {2010}, month = {10/2010}, publisher = {16th Biennial Mogollon Archeology Conference}, organization = {16th Biennial Mogollon Archeology Conference}, address = {Las Cruces, NM}, abstract = {Mesquite (Prosopis glandulosa) is among the most successful plants in Northern M{\'e}xico and America{\textquoteright}s arid Southwest. Mesquite optimizes pollinator services and reproductive effort, resulting in seeds that persist in herbivore digestive tracts and soil seed banks for extended periods. An extensive root system fully occupies the soil profile long distances from its base, allowing it to harvest water and nutrients with extraordinary efficiency. Root nodules harbor nitrogen-fixing bacteria allowing mesquite to overcome usual nitrogen limitations. Mesquite survival is determined early, but once established, it is long-lived, often benefiting from hardships killing most plants. So with mesquite{\textquoteright}s superior adaptations and competitive advantage, why has it only recently dominated desert landscapes? An answer may reside in the literature housing the knowledge of anthropologists and archaeologists studying the Jornada Mogollon, and prehistoric peoples of North America{\textquoteright}s warm deserts. Extensive use of mesquite by prehistoric peoples maybe a mechanism for dispersal of desert shrubs during the Holocene and controlling its distribution prior to European influence. A long-view of mesquite demography appears essential for reinterpreting our relationship with mesquite. A relationship that now cost millions of dollars annually to control its abundance and provide for lost ecosystem services.}, author = {E.L. Fredrickson and Curtis H. Monger and Guevada, Eduardo P.} } @article {50095, title = {Synthesis and assessment product 4.2: Tresholds of climate change in ecosystems}, year = {2009}, month = {2009 January}, publisher = {USGS}, abstract = {

In the past three decades, climate change has become a pronounced driver of ecosystem change. Changes in phenology, range shift of species, and increases in disturbances such as wildfires have all reflected ecosystem scales responses to a warming biosphere. There have also been abrupt, nonlinear changes in ecosystems where the level of response to incremental increases in temperature have suddenly changed trajectories. These thresholds of ecosystem change are not well understood but are potentially critical to adaptation strategies for managing natural resources in a rapidly changing world. This synthesis is intended to evaluate the current state of understanding of thresholds and to recommend possible actions to improve knowledge and adjust management priorities even with incomplete understanding of what drives thresholds of change and when they will occur.

}, keywords = {assessment, ecosystem, government publication, synthesis, threshold}, url = {/files/bibliography/09-005.pdf}, author = {Fagre, D.B. and Charles, C.W. and C.D. Allen and Birkeland, C. and F.S. Chapin III and Peter M. Groffman and Guntenspergen, G.R. and A. K. Knapp and A. D. McGuire and Mulholland, J.P. and Debra C. Peters and Roby, D.D. and Sugihara, G.} } @conference {50096, title = {Linking biological conservation to healthy rural communities: a case history of the Janos {\textendash} Casas Grandes Biosphere Reserve}, booktitle = {Ecological Society of America}, year = {2009}, note = {Abstract $\#$ 20230}, month = {08/2009}, pages = {COS 103-6}, address = {Albuquerque, NM}, abstract = {

During the late 1930\’s, Aldo Leopold witnessed a striking contrast along the narrow boundary between the United States and Mexico. He later described Mexican ecosystems as a \“lovely picture of ecological health\” and those same ecosystems north of the U.S. - Mexico border as \“so badly damaged that only tourists and those ecologically blind, can look upon them without a feeling of sadness, and regret.\” On this the hundredth centennial of Leopold\’s arrival in the Southwest, the difference has waned but has not completely vanished. Within Mexico\’s Janos \– Casas Grande region lays the largest black-tailed prairie dog complex within North America, reminiscent of past ecosystems just north of the border. Now a Biosphere Reserve, collaborative efforts between Mexican and U. S. scientists are reconstructing the area\’s ecological history and identifying key ecosystem properties maintaining grasslands and essential ecosystem services.

}, keywords = {abstract, biological conservation, Casa Grandes Biosphere Reserve, ESA, Janos}, author = {E.L. Fredrickson and G. Ceballos and List, R. and Barajas, N. and N. F. Sayre and Roacho, E.J.O. and Sierra, C.R. and G.E. Ponce and A.D. Davidson and Melgoza, A. and Jaquez, C. and G. Bezanilla} } @article {50206, title = {Higher effect of plant species diversity on productivity in natural than artificial ecosystems}, journal = {Proceedings of the National Academy of Sciences}, volume = {105}, year = {2008}, note = {//OTHER//OTHER//entered 06/02/2008 per DEP}, month = {2008}, pages = {6087-6090}, keywords = {article, biodiversity, plant, carbon cycle, ecosystem, artificial, ecosystem, natural, journal, Patagonian steppe, resource partitioning}, author = {P. Flombaum and O. E. Sala} } @conference {50207, title = {Landscape histories, livestock management, and mesquite expansion in the Chihuahuan Desert of New Mexico}, booktitle = {Society for Range Management Annual Meeting}, year = {2008}, month = {January 26, 2008}, pages = {2188}, address = {Louisville, KY}, abstract = {During the past 125 years the northern Chihuahuan Desert has undergone a significant shift from desert grasslands to desert shrub conditions, with mesquite (Prosopis glandulosa) dramatically increasing in dominance during this period. The transition from desert grasslands is viewed as deleterious, decreasing forage availability for both wildlife and livestock while negatively impacting air, water, and soil processes that support ecosystem services important to rapidly growing, human populations. Causes leading to this transition include formulation of government and industry policies, and later application of some range management principles, without an understanding of the evolutionary and landscape history of the northern Chihuahuan Desert. In addition, as causes of mesquite expansion were determined, primary factors leading to mesquite{\textquoteright}s eventual dominance did not receive adequate attention, most likely because they did not fit within dominant scientific paradigms, or social-political realities of the time. Future work needs to focus on better understanding evolutionary and landscape legacies of this region; including factors that created and maintained the original desert grasslands prior to desert scrub conditions. Using this understanding we must create appropriate theory that will guide future human-ecological interactions and assessment of ecological trajectories. This knowledge must affect policy and eventual management. We must relax the need for ecosystems to adapt to human behaviors and consider how human behaviors can best adapt to the ecosystems on which they depend.}, keywords = {Chihuahuan Desert}, author = {E.L. Fredrickson and Jeffrey E. Herrick and H. Raul Peinetti and Andrea S. Laliberte} } @article {JRN54005, title = {Detecting land cover change at the Jornada Experimental Range, New Mexico with ASTER emissivities}, journal = {Remote Sensing of Environment}, volume = {112}, year = {2008}, month = {04/2008}, pages = {1730-1748}, chapter = {1730}, abstract = {

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

}, keywords = {ASTER, emissivity, Jornada, land cover change, MODIS, Thermal infrared}, doi = {10.1016/j.rse.2007.08.020}, author = {A.N. French and T. J. Schmugge and Jerry Ritchie and A.F. Hsu and Jacob, F. and Ogawa, K.} } @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} } @article {50329, title = {Volatile compounds on the leaf surface of intact and regrowth tarbush (Flourensia cernua DC) canopies}, journal = {Journal of Chemical Ecology}, volume = {33}, year = {2007}, month = {September 25, 20}, pages = {1867-1875}, abstract = {

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

}, keywords = {Flourensia cernua, plant secondary metabolites, regrowth, tarbush, terpenes}, doi = {10.1007/s10886-007-9360-8 }, url = {/files/bibliography/07-029.pdf}, author = {E.L. Fredrickson and Richard E. Estell and M.D. Remmenga} } @article {50441, title = {Use of low-temperature scanning electron Microscopy to compare and characterize three classes of snow cover}, journal = {Scanning}, volume = {28}, year = {2006}, month = {12/2006}, pages = {191-203}, abstract = {

This study, which uses low temperature scanning electron microscopy (LTSEM), systematically sampled and characterized snow crystals that were collected from three unique classes of snow cover: prairie, taiga and alpine. These classes, which were defined in previous field studies, result from exposure to unique climatic variables relating to wind, precipitation and air temperature. Snow samples were taken at 10 cm depth intervals from the walls of freshly excavated snow pits. The depth of the snow pits for the prairie, taiga and alpine covers were 28 cm, 81 cm and 110 cm, respectively. Visual examination revealed that the prairie snow cover consisted of two distinct layers whereas the taiga and alpine covers had four distinct layers. Visual measurements were able to establish the range of crystal sizes that occurred in each layer, the temperature within the pit and the snow density. The LTSEM observations revealed the detailed structures of the types of crystals that occurred in the snow covers and documented the metamorphosis that transpired in the descending layers. Briefly, the top layers from two of the snow covers, consisted of freshly fallen snow crystals that could be readily distinguished as plates and columns (prairie) or graupel (taiga). Alternatively, the top layer in the alpine cover consisted of older dendritic crystal fragments that had undergone early metamorphosis, i.e. they had lost their sharp edges and had begun to show signs of joining or bonding with neighboring crystals. A unique layer, known as sun crust, was found in the prairie snow cover; however, successive samplings from all three snow covers showed similar stages of metamorphism that led to the formation of depth hoar crystals. These changes included the gradual development of large, three-dimensional crystals having clearly defined flat faces, sharp edges, internal depressions and facets. The study, which indicates that LTSEM can be used to enhance visual data by systematically characterizing snow crystals that are collected at remote locations, is important for understanding the physics of snowpacks and the metamorphosis that leads to potential avalanche situations. In addition, the metamorphosis of snow crystals must be considered when microwave radiometry is used to estimate the snow water equivalent in the winter snowpack, because large snow crystals more effectively scatter passive microwave radiation than small crystals. http://http://www3.interscience.wiley.com/cgi-bin/fulltext/113509454/PDFSTART

}, keywords = {depth hoar, low temperature scanning electron, snow cover, snow crystal}, url = {/files/bibliography/07-020.pdf}, author = {J. Foster and R. Kelly and A. Rango and Armstrong, R. and E. R. Erbe and C.D. Pooley and W.P. Wergin} } @article {50442, title = {Mesquite recruitment in the Chihuahuan Desert: historic and prehistoric patterns with long-term impacts}, journal = {Journal of Arid Environments}, volume = {65}, number = {2}, year = {2006}, month = {April 1, 2006}, pages = {285-295}, abstract = {Mesquite (Prosopis glandulosa) has increased in dominance over large areas of the Chihuahuan Desert, chiefly at the expense of once expansive desert grasslands. Excessive grazing and seed dissemination by livestock are often cited as the cause of this transition. We propose an alternate hypothesis that expansion of mesquite is not simply due to cause and effect relationships during recent history; rather, mesquite expansion is a result of a series of cause and effect relationships that transpired over a much longer timeframe (centuries). We assert that mesquite expansion may have ultimately occurred in the absence of widespread livestock grazing during the last 130 years because of removal of barriers to mesquite expansion created by Pleistocene megafauna and indigenous peoples. We explore factors that attenuate or intensify mesquite expansion and examine how a series of fine=scale, but temporally seminal, events can propagate across multiple scales. Furthermore, we examine the relevance of this hypothesis for present day remediation of shrub-dominated grasslands and conclude that knowledge of historic and prehistoric events and processes are essential to effectively manage landscapes. http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-4HSY4WS-3-5\&_cdi=6845\&_user=1496926\&_orig=browse\&_coverDate=04\%2F30\%2F2006\&_sk=999349997\&view=c\&wchp=dGLbVtz-zSkWW\&md5=a516e16003fd57a18d1e636650b3d2eb\&ie=/sdarticle.pdf}, keywords = {historic legacy, invasive species, landscape history, prosopis glandulosa, seed dispersal}, url = {/files/bibliography/06-001.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Andrea S. Laliberte and D.M. Anderson} } @article {50548, title = {Desert grassland canopy arthropod species richness: temporal patterns and effects of intense, short-duration livestock grazing}, journal = {Journal of Arid Environments}, volume = {60}, number = {4}, year = {2005}, month = {March 1, 2005}, pages = {627-646}, abstract = {

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

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

}, keywords = {arthropods, canopy, Chihuahuan Desert, desert grassland, livestock grazing, species richness}, doi = {10.1016/j.jaridenv.2004.07.004}, url = {/files/bibliography/05-020.pdf}, author = {Gregory S. Forbes and Justin Van Zee and W. E. Smith and Walter G. Whitford} } @conference {50549, title = {Collaborative animal science research: impacts of agriculture and trade policies on cross-border rangeland research and management}, booktitle = {Society for Range Management, 58th Annual Meeting and Trade Show}, year = {2005}, month = {February 5, 2005}, pages = {Paper No. 115}, address = {Fort Worth, TX}, abstract = {In sharing a common boundary, Mexico and the United States also shares common landscapes and an agricultural economy that is inextricably linked. Due to the high degree of connectedness between these countries, factors that affect one country also affect the other, either directly or indirectly. Current problems in the border region include extended drought, land degradation, and depletion of essential resources such as water. These problems are exacerbated by ensconced political and social systems resistant to change. The implications of these events are profound, and often referred to as being near catastrophic. Collaborative research between Mexican and US researchers offers numerous benefits by combining human and material resources to solve common problems. Despite these benefits, language, social customs, and political policies can create barriers to collaborative efforts that reduce the effectiveness and the overall number of collaborative efforts. When anticipated and appropriately planned for, these barriers can effectively be dealt with. We discuss these potential barriers and how to address them by relating our experiences with collaborative Mexican-US projects on the conservation and use of northern Mexican criollo beef cattle breeds in semiarid and arid environments.}, keywords = {agriculture and trade policies, animal science research, cross-border, management, rangeland, research}, author = {E.L. Fredrickson and G. Bezanilla} } @conference {50552, title = {Criollo Cattle: An Examination of the Past with an Eye to the Future}, booktitle = {American Society of Animal Science, New Mexico Branch American Association of Laboratory Animal Scientists}, year = {2005}, month = {August 5, 2005}, address = {New Mexico State University, Las Cruces, NM}, abstract = {During his second voyage in 1492, Columbus introduced the first cattle to the New World. Since their introduction from Andalusia, these cattle have undergone 500 year sof co-evolution with the lanscapes of North and South America. Focusing on arid regions of Chihuahua, Sonora, and Baja California, we are undertaking a series of studies to better understand the arid land adaptations of "criollo" cattle and their potential effects on vegetation change. While the oldest breed in the United States, these cattle may again prove useful in shaping the future of the North American beef cattle industry.}, keywords = {1492, Andalusia, cattle, Columbus}, author = {E.L. Fredrickson and Richard E. Estell} } @conference {50550, title = {Drought as a Dynamic Process: Recovering from Long Term Rangeland Impacts of Drought}, booktitle = {2005 3rd Annual Drought Summit: "The Drought: It Ain{\textquoteright}t OVer {\textquoteright}Til It{\textquoteright}s Over, and It Ain{\textquoteright}t Over!", USDA Natural Resources Conservation Service}, year = {2005}, month = {October 6, 2005}, pages = {pp. 20}, publisher = {University of New Mexico Continuing Education Center}, organization = {University of New Mexico Continuing Education Center}, address = {Albuquerque, NM}, abstract = {Central tenets of living with drought rangelands are complex, often unpredictable lanscapes, in which drought is a constant feature. The effects of drought are dependent on prior conditions that are largely the result of the continual interplay of humans and their environment. By investing in human capital, and the large social context, we can better manage this interplay to meet a diversity of needs. It is knowledge, and the creation of knowledge, through monitoring and scientific investigation, that allows land management professionals to better adapt and innovate to ever chaning conditions. Likewise, the greater society provides the ethic and the needed flexibility for the land manager to operate within. Without first adressing this often ignored framework, use of other management tools are likely to be costly, have short-lived benefits, and uninteded consequences.}, keywords = {drought management, long term, rangeland}, author = {E.L. Fredrickson} } @article {50651, title = {Advances in theory, instrumentation, semiconductor, and materials applications of scanning microscopy}, journal = {Scanning}, volume = {26}, number = {2}, year = {2004}, month = {March 1, 2004}, pages = {68-69}, abstract = {It is important to monitor the development of seasonal snow cover classes (tundra, taiga, alpine, maritime, prairie and ephemeral) worldwide and to visualize and understand snow crystal metamorphism. Low-temperature, scanning electron microscopy provides a superior form of snow crystal imaging and was successfully tested in taiga, alpine and prairie snowpacks with approximately 50\% of the total depth made up of depth hoar crystals. The technique can be used easily for field data collection and provides a new tool for studying important snowpack processes with applications to avalanche and water supply forecasting.}, keywords = {alpine, crystal, maritime, snow, taiga, tundra}, url = {/files/bibliography/04-056.pdf}, author = {J. Foster and A. Rango and E. G. Josberger and E. R. Erbe and C.D. Pooley and W.P. Wergin} } @conference {50652, title = {Management effects on livestock use of landscapes: Protein supplementation}, booktitle = {89th Annual Meeting, Ecological Society of America}, year = {2004}, month = {August 1, 2004}, pages = {Abstract p. 166}, address = {Portland, OR}, abstract = {Over half of the Earth{\textquoteright}s land surface is grazed by livestock. The effects of livestock grazing on terrestrial ecosystems range from detrimental to beneficial depending on ecosystem attributes and livestock management. Understanding the ecological implications of livestock management decisions is central to successful human interactions with complex environments. For example, supplementing heifers with a 32\% protein supplement concentrated heifer movements in areas near water and supplementation points. Prior to supplementation, animal movements were dispersed throughout the pasture. While concentrated movements are at times desirable, they can also trigger undesirable ecosystem trajectories. As part of a larger goal to better understand the ecological impacts of livestock grazing, we designed a study to examine the effects of protein supplementation, a common management practice, on livestock use of landscapes. Thirty-six multiparous, lactating, Angus x Hereford cows were randomly assigned to one of three treatments: (1) control (CON), no supplementation, (2) supplementation each day at 0700 (AM) with 0.75 kg of a 32\% crude protein pellet, or (3) supplementation at 1300 (PM) each day with the same supplement. Fifteen days prior to the study, animals were allowed to become familiar with experimental procedures and the 2,425 ha study pasture described as Chihuahuan Desert grassland ecotype. Animals from each treatment were fitted with Lotek GPS collars and rotated into the study pasture for a period of 5 days for three rotations. Animal position was acquired every 5 minutes. Mean distance from water differed (P < .0001) across treatments (2.55, 2.09, and 1.53 km for CON, PM, and AM, respectively). Distance traveled per day also differed (P < .0001) across treatments (7.17, 7.20, and 7.96 km/day for CON, PM, and AM, respectively). The area encompassing daily activities (Jennrich-Turner estimate of home range) also differed (P < .0001; 4.3, 2.8, and 3.9 square km/day for CON, PM, and AM, respectively). Protein supplementation and timing of supplementation affect the spatial use of desert grasslands and is likely to have important ecological implications. Furthermore, research examining livestock impacts must do so with an understanding of the effects of management on livestock behavior.}, keywords = {ecological impacts, ecosystems, livestock, livestock behavior, livestock management, protein supplementation}, author = {E.L. Fredrickson and J. Koppa and Richard E. Estell and D.M. Anderson and Kris Havstad} } @conference {50653, title = {Mesquite recruitment: historic patterns with long-term impacts}, booktitle = {Sixth Symposium on the Natural Resources of the Chihuahuan Desert Region}, year = {2004}, month = {October 15, 2004}, pages = {24}, address = {Alpine, TX}, abstract = {Mesquite (Prosopis glandulosa Torrey) has increased in dominance over large areas of the Chihuahuan Desert, chiefly at the expense of once expansive desert grasslands. Excessive grazing and seed dissemination by livestock are often attributed as the cause of this transition. We propose an alternate hypothesis that expansion of mesquite is not due to simple cause and effect relationships, but rather a network of cause and effect relationships. We assert that mesquite expansion may have occurred even in the absence of the widespread livestock grazing occurring during the last 130 years. We then look at factors that attenuate or intensify mesquite expansion and how a series of small-scale but temporally seminal events propagate across multiple scales. Lastly, we examine how acceptance of this hypothesis, or its parts, might be useful in enhancing 21st century efforts focused on remediation of desert grasslands.}, keywords = {Chihuahuan Desert, excessive grazing, long-term impacts, mesquite, patterns, seed dissemination, small-scale events}, author = {E.L. Fredrickson and Laurie Abbott and D.M. Anderson and Richard E. Estell} } @article {50860, title = {Do morphological changes mediate plant responses to water stress? A steady-state experiment with two C4 grasses}, journal = {New Phytologist}, volume = {155}, number = {1}, year = {2002}, note = {//USDA//LTER IV//entered 6/27/2002; updated 4/7/2009; pdf available}, month = {2002}, pages = {79-88}, abstract = {It was hypothesized that plant growth reduction under water stress is caused primarily by a reduction of leaf-area ration (LAR, leaf area per unit of total plant dry mass). Two perennial Chihuahuan desert grass species (slow-growing Bouteloua eriopoda and fast-growing Eragrostis lehmanniana) were subjected over 6 weeks to a combination of two water-supply regimes (control and drought) and two levels of atmospheric CO2 partial pressure (375 and 750 {\`\i}mol mol-1). Drought reduced final biomass in Bouteloua by 60\% regardless of CO2 concentration. Eragrostis experienced a similar biomass reduction at 375 {\`\i}mol mol-1, but large plants under elevated CO2 attained growth rates comparable to those of controls. Overall, for plants of similar size, drought reduced LAR in both species much more strongly than it affected net assimilation rate. This reduction in LAR was caused by reductions in both specific leaf area and leaf weight ratio. We conclude that reduced growth under drought can be considered as a byproduct of the same plastic, developmental responses that result in a reduced water loss.}, keywords = {article, articles, Bouteloua eriopoda, Bouteloua, drought, Bouteloua, growth analysis, Bouteloua, plasticity, Bouteloua, water use efficiency (WUE), drought tolerance, grass, drought, Bouteloua, drought, Eragrostis, Eragrostis lehmanniana, Eragrostis, drought, Eragrostis, growth analysis, Eragrostis, plasticity, Eragrostis, water use efficiency (WUE), journal, journals, plant, Bouteloua, plant, Eragrostis, water-use efficience, Bouteloua, water-use efficiency, Eragrostis}, url = {http://www.newphytologist.com}, author = {Roberto J. Fern{\'a}ndez and Wang, Mengben and J. F. Reynolds} } @conference {50861, title = {Effects of fire and mowing on expansion of reestablished black-tailed prairie dog colonies in Chihuahuan Desert grasslands}, booktitle = {2002 Fire Conference}, volume = {General Technical Report PSW-189}, year = {2002}, month = {December 2-5, 20}, pages = {49}, address = {San Diego, CA}, abstract = {Black-tailed prairie dogs (Cynomys ludovicianus) currently occupy less than 2\% of their historical range. This decline is due to eradication programs, habitat loss, and introduced pathogens. Active conservation measures for this species, including reintroduction, are underway in a number of areas. Prairie dogs are a key species in grassland ecosystems because of their effects on landscape pattern and ecosystem process. As part of a larger study of reciprocal effects of landscape and ecosystem factors on establishment and growth of prairie dog colonies, we investigated the effects of fire and mowing on numerical growth and aerial expansion of colonies reintroduced into the northern Chihuahuan Desert. On each of three colonies, established in 1998-1999 and ranging from 1.27 to 8 ha, we established six 50x50m experimental plots randomly assigned to burn or mowing treatments. The response variable was the number of new burrows appearing in each experimental plot. Results show no significant differences in the number of new burrows in burned vs. mowed plots; therefore, fire and mowing can be used interchangeably as management tools to reintroduce prairie dogs.}, author = {P. L. Ford and C.A. Anderson and E.L. Fredrickson and J. Truett and G. Roemer} } @conference {50862, title = {Fire as a management tool to facilitate expansion of reintroduced black-tailed prairie dog colonies in Chihuahuan Desert grasslands}, booktitle = {16th Annual Meeting, Society for Conservation Biology}, year = {2002}, month = {July 14, 2002}, pages = {3}, address = {Canterbury, UK}, abstract = {Within the last hundred years, public and private control programs and plague have reduced black-tailed prairie dog (Cynomys ludovicianus) population numbers by 98\%, causing localized extinctions. Black-tailed prairie dogs significantly alter grassland ecosystems and are considered a "keystone" species requiring active conservation efforts. We report on an experimental study evaluating fire vs. mowing for facilitating expansion of reintroduced colonies. We used three northern Chihuahuan Desert (Sporobolus/Scleropogon grassland association) colonies reestablished in 1998-99 ranging from 1.27 to 8 ha. Contiguous taller grasses limited expansion of these colonies. We established six 50x50m experimental plots adjacent to each colony randomly assigned to burn or mow treatments. All burrows in each colony were mapped immediately preceding treatment and 4-months after treatment. Numbers of newly established burrows in each plot were used as a measure of habitat preference. Results indicate no significant differences in the number of new burrows on burn (mean = 13, SD = 8) vs. mow (mean = 13, SD = 5) plots. In conclusion, fire can be used in lieu of mowing as a tool. Persistence of these treatments will depend on prairie dog population dynamics and impact of treatments on the foraging dynamics of associated large ungulates.}, author = {P. L. Ford and E.L. Fredrickson and C.A. Anderson and J. Truett} } @proceedings {50864, title = {Complexity, desertification and livestock production: Dancing with the winds of change}, year = {2002}, month = {September 19-21,}, pages = {1-4}, address = {Chihuahua, Mexico}, abstract = {During the last 150 years the Jornada Experimental Range has undergone a transition from desert grasslands to desert scrubland vegetation. This transition is characteristic of desertification, a process occurring in arid and semiarid regions worldwide. While livestock grazing is commonly isolated as the sole driver of desertification in the northern Chihuahuan Desert, it appears that actual causes are complex and difficult to untangle. Principal factors thought to cause current desertified conditions are shifts in seasonal precipitation with winter precipitation favoring shrubs and summer rainfall favoring grasses. Increasing CO2 may have a fertilization effect that favors C3 shrubs over C4 grasses. Human effects on mammalian predator-prey dynamics may have caused alterations in small herbivore populations that normally dampen oscillations in plant demographics. Whether current trends in desertification are due to human or non-human forces is, at present, indeterminable. What is certain is that we live in an environment that is complex, chaotic, and at times catastrophic. Our world is dynamic, constantly evolving, and rarely at equilibrium. Future success will result because of a society{\textquestiondown}s ability to adapt and innovate in response to change, and to do so within an ethical framework that creates potential benefit to current and future societies.}, author = {E.L. Fredrickson and Amy L. Gonzalez} } @proceedings {50865, title = {Desertification: Weaving together the complexities of time and place}, year = {2002}, month = {September 17-20,}, pages = {18-26}, address = {Durango, Mexico}, abstract = {Desertification is an active process in the Chihuahuan Desert that is typified by a vegetation transition from desert grasslands to desert scrub. Throughout much of geological time, deserts have waxed and waned without human intervention. Currently, it is difficult to segregate human and nonhuman causes. One obvious cause of this transition is a dynamic interaction between plant species with and without specific adaptations to large animal herbivory. An examination of vegetation change with time reveals that deserts are complex, chaotic, and often catastrophic. New models are being developed to deal with the resulting uncertainty. These models include complex adaptive systems and adaptive management. These models are discussed and applied to conditions prevalent in the Chihuahuan Desert.}, url = {/files/bibliography/02-023.pdf}, author = {E.L. Fredrickson and Amy L. Gonzalez} } @conference {50863, title = {Mowing versus fire on expansion of black-tailed prairie dogs reintroduced into Chihuahuan Desert grasslands}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {352}, address = {Tucson, AZ}, abstract = {Black-tailed prairie dogs (Cynomys ludovicianus) populations have declined more than 98\% due to eradication programs, habitat loss, and introduced pathogens. Active conservation measures for this species, including reintroduction, are under way in a number of areas. Because of their effects on landscape pattern and ecosystem process, they may act as a keystone species in desert grassland communities. As part of a larger study of reciprocal effects of landscape and ecosystem factors on establlishment and growth of prairie dog colonies, we investigated the effects of fire and mowing in promoting colony numerical growth and areal expansion. Three prairie dog colonies were established in the northern Chihuahuan Desert in 1998-1999 ranging in size from 1.27 to 8 ha. Adjacent to each colony we established six 50m x 50m experimental plots randomly assigned to burn or mow treatments. The response variable was number of new burrows appearing in each experimental plot. No significant differences were detected in the number of new burrows in burned vs. mowed plots, suggesting that either fire or mowing can be used interchangeably as management tools in the reintroduction of prairie dogs.}, author = {E.L. Fredrickson and C.A. Anderson and P. L. Ford and J. Truett and G. Roemer} } @article {50986, title = {Response of individual Bouteloua gracilis (gramineae) plants and tillers to small disturbances}, journal = {American Midland Naturalist}, volume = {145}, number = {1}, year = {2001}, month = {January 1, 2001}, pages = {147-158}, abstract = {We evaluated effects of small disturbances that kill parts of individual plants on plant survival by measuring tiller survival for the perennial bunchgrass, Bouteloua gracilis (H.B.K.) Lag ex Griffiths (blue grama). The importance of soil texture, grazing by cattle, disturbance type, and severity were evaluated. Two disturbance types (covering or removing tillers) and three disturbance severities (50, 75, and 90\% tiller mortality) were used to represent effects of natural disturbances in shortgrass communities (cattle fecal pats, nest sites of Western harvester ants, burrows of small animals). Tiller survival through time was not affected by soil texture or grazing intensity, but was affected by disturbance type and severity. Plants that were partially covered showed a 33\% increase in tiller survival for all levels of severity from August (1991) to June (1992). No net change in tiller number was observed for partially removed or control plants. The number of tillers produced was small, but significant (avg=20 tillers/plant), which suggests that B. gracilis plants do not contain independent tillers, but consist of integrated physiological units (IPUs). The lack of plant mortality even with 90\% tiller mortality indicates that small disturbances must kill entire plants before gaps in resource space are produced, and gap dynamics are initiated that result in the recovery of an individual B. gracilis plant. Because recovery through seedling establishment by B. gracilis occurs infrequently, the ability of this species to survive after partial plant mortality is important to its continued dominance of shortgrass steppe communities in the presence of these small, but frequent disturbances.}, keywords = {Bouteloua gracilis (gramineae), cattle grazing, disturbances, soil texture}, url = {/files/bibliography/02-017.pdf}, author = {J.L. Fair and Debra C. Peters and W. K. Lauenroth} } @article {50987, title = {Pen confinement of yearling ewes with cows or heifers for 14 days to produce bonded sheep}, journal = {Small Ruminant Research}, volume = {40}, year = {2001}, month = {June 1, 2001}, pages = {291-297}, abstract = {

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

}, keywords = {beef cattle, bonded sheep, bonding, cows, heifers, Mixed species stocking, Multispecies stocking, pen confinement, sheep, yearling ewes}, doi = {10.1016/S0921-4488(01)00183-3}, url = {/files/bibliography/01-022.pdf}, author = {E.L. Fredrickson and D.M. Anderson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and M.D. Remmenga} } @article {51069, title = {Potential growth and drought tolerance of eight desert grasses: lack of a trade-off?}, journal = {Oecologia}, volume = {123}, number = {1}, year = {2000}, note = {//NMSU,USDA//LTER III//updated keywords 4/7/2009; pdf available}, month = {2000}, pages = {90-98}, abstract = {

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

}, keywords = {article, articles, C-4, drought tolerance, grass, grass, drought tolerance, journal, journals, photosynthetic pathway, plant, Aristida purpurea, plant, Bouteloua eriopoda, plant, Eragrostis lehmanniana, plant, Hilaria mutica, plant, Muhlenbergia porteri, plant, Panicum obtusum, plant, Scleropogon brevifolius, plant, Sporobolus flexuosus, water stress, xerophytism}, doi = {10.1007/s004420050993 }, url = {files/bibliography/JRN00310.pdf}, author = {Roberto J. Fern{\'a}ndez and J. F. Reynolds} } @article {51070, title = {Regional snow parameters derived from microwave radiometry}, journal = {EOS Transactions, American Geophysical Union}, volume = {81}, year = {2000}, note = { //NONE//LTER IV//updated 08/04/2010}, month = {2000}, pages = {F445}, author = {J. Foster and Chang, A. T. C. and D. K. Hall and E. R. Erbe and W.P. Wergin and A. Rango} } @article {51071, title = {The effect of feeding ewe lambs a 15\% tarbush (Flourensia cernua DC) pellet pre- and post-weaning on the subsequent diet selection of tarbush}, journal = {Journal of Arid Environments}, volume = {44}, number = {1}, year = {2000}, month = {January 1, 2000}, pages = {123-131}, abstract = {

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

}, keywords = {ewe lambs, Flourensia cernua, post-weaning, pre-weaning, tarbush}, doi = {10.1006/jare.1999.0571}, url = {/files/bibliography/00-003.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @article {51142, title = {Demography of Bouteloua gracilis in a mixed prairie: analysis of genets and individuals}, journal = {Journal of Ecology}, volume = {87}, number = {2}, year = {1999}, month = {April 1, 1999}, pages = {233-243}, abstract = {

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

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

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

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

}, keywords = {clonal fragmentation, grassland, mortality, plants, recruitment}, doi = {10.1046/j.1365-2745.1999.00344.x}, url = {/files/bibliography/653.pdf}, author = {J.L. Fair and W. K. Lauenroth and D.P. Coffin} } @article {51144, title = {Burrowing activities of kangaroo rats and patterns in plant species dominance at a shortgrass steppe-desert grassland ecotone}, journal = {Journal of Vegetation Science}, volume = {10}, year = {1999}, month = {1999}, pages = {123-130}, abstract = {

Our objective was to evaluate the effects of burrowing activities by banner-tail kangaroo rats (Dipodomys spectabilis Merriam) on plant community structure and species dominance for two patch types at the ecotone between shortgrass steppe and desert grassland in New Mexico, USA. 10 mounds produced by kangaroo rats were selected in patches dominated by Bouteloua gracilis (the dominant in shortgrass steppe communities) and 10 mounds were selected in patches dominated by B. eriopoda (the dominant in Chihuahuan desert grasslands). Plant cover and density by species were sampled from three locations associated with each mound: the mound proper, the edge of the mound in the transition area, and the off-mound vegetation. Similar cover of B. eriopoda for the edges of mounds in both patch types indicates the ability of this species to respond to animal disturbances regardless of the amount of cover in the surrounding undisturbed vegetation. By contrast, cover of B. gracilis was low for all mounds and mound edges in patches dominated by this species. Much higher cover of B. eriopoda on mound edges compared to the undisturbed vegetation in B. gracilis-dominated patches indicates that kangaroo rats have important positive effects on this species. Lower cover of perennial grasses and higher cover of forbs, shrubs, and succulents on the edges of mounds in B. eriopoda-dominated patches compared to patches dominated by B. gracilis indicate the importance of surrounding vegetation to plant responses on disturbed areas.

}, keywords = {Bouteloua, Chihuahuan Desert, Dipodomys spectabilis, disturbance, dominant species, kangaroo rat}, doi = {10.2307/3237167}, url = {/files/bibliography/654.pdf}, author = {Fields, M.J. and D.P. Coffin and J. R. Gosz} } @article {51143, title = {The role of kangaroo rats (Dipodomys spectabilis) in determining patterns in plant species dominance at an ecotonal boundary}, journal = {Journal of Vegetation Science}, volume = {10}, year = {1999}, month = {1999}, pages = {123-130}, author = {Fields, M.J. and Debra C. Peters and J. R. Gosz} } @conference {51145, title = {Using CENTURY to investigate ecosystem effects of a non-native species and implications for restoration}, booktitle = {84th Annual Meeting, Ecological Society of America}, volume = {80}, year = {1999}, month = {August 8-12, 199}, address = {Spokane, WA}, abstract = {Acroptilon repens (Russian knapweed), a non-native perennial composite, can form monospecific stands lasting decades on western rangeland. Biological control has limited success on A. repens expansion. Currently successful restoration efforts involve three key steps: herbicide application, soil cultivation, and seeding to grass. Cultivation is thought to release volatile allelochemicals trapped in the soil; however, cultivation can change many soil characteristics, including organic matter decomposition rates and nutrient availability. In order to simulate nitrogen cycles on paired rangeland plots dominated by either grass or A. repens, we used the CENTURY model with appropriately adjusted lignin:N and growth parameter values. CENTURY results suggest that net nitrogen mineralization is significantly reduced in soils under A. repens relative to soils under grass. After conversion from grass to A. repens domination, labile soil nitrogen pools decrease rapidly within the first couple of years, while slow soil nitrogen pools gradually increase for decades. Following chemical control and cultivation, the model predicts net nitrogen mineralization rates and labile soil nitrogen pools increase, in a pulse lasting a few years, to levels greater than that occurring in the paired grass-dominated rangeland. An empirical study is warranted to investigate whether the expected increase in nitrogen availability following cultivation is responsible for improved restoration success associated with cultivation, and if no-till restoration could be successful with nitrogen applications.}, author = {Fraleigh, H.D. and Debra C. Peters and Beck, K.G. and William Parton} } @conference {51146, title = {Role of herebivorous and granivorous fauna in the maintenance of mesquite coppice dune systems}, booktitle = {5th Symposium on Resources of the Chihuahuan Desert Region: U.S. and Mexico}, year = {1999}, month = {October 7-8, 199}, pages = {17-18}, address = {Alpine, TX}, abstract = {Part of the ongoing desertification process within the Chihuahuan Desert involves replacement of former grasslands by shrubs. At the U.S. Department of Agriculture, Agricultural Research Service, Jornada Experimental Range, vast areas of Black Grama, Bouteloua eriopoda, grasslands were replaced by mesquite, Prosopis glandulosa glandulosa, which hsubsequently facilitates the formation of coppice dunes or mounds of sand around established shrubs. Three studies were designed to assess the effects of two broad guilds of fauna herbivores (foliage eaters) and granivores (seed eaters) in maintaining coppice dune states. We also consider in greater detail species-specific roles played by a group of desert rodents known to have keystone effects on Chihuahuan Desert plant communities. These studies indicate the small mammals studied both maintain and probably augment coppice dune systems.}, author = {E.L. Fredrickson and Longland, W.S. and P.W. Hyder and Hu, D. and Richard E. Estell} } @conference {51214, title = {Dispersal of Lehmann lovegrass by sheep}, booktitle = {Annual Meeting, Society for Range Management}, year = {1998}, month = {1998}, pages = {38}, abstract = {Lehman lovegrass seed are dispersed by wind and water; however, domestic animals also may be effective seed dispersal agents. Animal dispersion of Lehmann lovegrass has not been examined and was the objective of the present study conducted on the Jornada Experimental Range during the years 1995 and 1996. Two seed dispersal methods were evaluated: broadcasting and seed dispersal via sheep feces using two levels of precipitation. To determine treatment effects the following variables were measured: percentage of plots with Lehmann lovegrass seedlings, number of seedlings per plot and seedling vigor at the end of the growing season. The results showed that broadcast seeding produced three to four times more plots with Lehmann lovegrass seedlings than seed dispersed in sheep feces. The number seedlings per plot also were higher in broadcast seeded plots. Seedling vigor at the end of the growing season did not differ by seed dispersal method. Precipitation level did not effect the variables measured. Although not as effective as broadcast seeding, the germination and persistence of Lehmann lovegrass seeds in sheep feces does indicate that sheep should be considered as dispersal agents of Lehmann lovegrass.}, author = {Flores, M.A. and E.L. Fredrickson and Pieper, Rex D. and L. W. Murray} } @conference {51215, title = {Concentrations and distributions of nordihydroguaiaretic acid, total phenolics and condensed tannins in creosotebush (Larrea tridentata)}, booktitle = {Annual Meeting, Society for Range Management}, volume = {51}, year = {1998}, month = {1998}, pages = {29}, abstract = {Creosotebush contains a variety of secondary metabolites that have important ecological roles. Some, such as nordihydroguaiaretic acid (NDGA), have been proposed to have allelopathic effects that may contribute to the rapid expansion of creosotebush. Studies suggest phenolic compounds in roots affect root longevity, soil microbial processes and may have allelopathic properties. While NDGA concentrations in the above ground fraction has been extensively studied, other phenolic compounds throughout the plant, including the roots, have received little attention. Five creosotebush plants were collected and divided into 9 tissue categories. These categories were then analyzed for concentrations of NDGA, total phenolics and condensed tannins. NDGA was confined to "green" tissues such as leaves, flowers and stem tips. Total phenolics were found in all tissues with leaves, green stems and roots containing the highest concentrations. Condensed tannins were found in relatively low concentrations throughout all tissues except for seeds, which had levels roughly 17 times the mean concentration found in the rest of the plant. Future studies will look at the role of phenolics in modifying the plants immediate environment including allelopathic effects on sympatric plant species.}, author = {E.L. Fredrickson and P.W. Hyder and M.R. Tellez and Richard E. Estell} } @article {51216, title = {Perspectives on desertification: Southwestern United States}, journal = {Journal of Arid Environments}, volume = {39}, year = {1998}, month = {1998}, pages = {191-207}, abstract = {

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

}, keywords = {Chihuahuan Desert, desertification, Sonoran Desert, south-west United States}, doi = {10.1006/jare.1998.0390}, url = {/files/bibliography/613.pdf}, author = {E.L. Fredrickson and Kris Havstad and Richard E. Estell and P.W. Hyder} } @article {51276, title = {Effects of ruminant digestion on germination of Lehmann lovegrass seed}, journal = {Journal of Range Management}, volume = {50}, number = {1}, year = {1997}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {January 1, 1997}, pages = {20-26}, abstract = {

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

}, keywords = {Eragrostis lehmanniana, in vitro digestibility, introduced species, mastication, rumen fermentation, seed dispersal, Seed germination, seeds, selective grazing, sheep, sheep dung}, doi = {10.2307/4002700 }, url = {/files/bibliography/582.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Ksiksi, T. and VanTol, J. and M.D. Remmenga} } @conference {51277, title = {Perspectives on desertification: Southwestern United States}, booktitle = {International Symposium Workshop, Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {1997}, pages = {10}, abstract = {Several climatic changes occurred in the northern Chihuahuan Desert and other parts of the southwest United States during the last 12,000 years, leading to a markedly warmer and drier climate. Vegetation also changed in response to the climatic shift. Generally this transition was from coniferous woodland to grasslands and eventually to the present day desert scrub. Pre-Columbian people occupying this region adapted by changing from hunter-gatherer to largely agrarian economies. During this time the level of cooperation among people apparently increased as shown by the formation of pueblos (cities) and greater trade among diverse regions. This increase in cooperation probably resulted as a response to increasing aridity and more frequent droughts. Recent European immigration into the southwest U.S. beginning in the mid 1500s greatly affected this region. The greatest impact occurred after the U.S. Civil War in the 1860s. Before the 1860s land use tended to be localized around small agricultural areas, mines, and military installations. After the war, however, the range livestock industry expanded dramatically, especially in the 1880s. During this time grazing land was viewed as limitless, but as H.L. Bentley stated in 1898, "... grasses were entirely consumed; their roots were trampled into the dust.. ." This period represents a time of general abuse of arid lands in the region. Recognition of the abuse and the deteriorating productivity of the land led to greater government involvement, including establishing experimental stations and eventually managing of the public domain by governmental agencies. Despite improved land management, desertification processes continue. Continued livestock grazing, changing climatic conditions, soil loss, and increasing atmospheric CO2 concentrations (mainly due to the burning of fossil fuels) are among the probable causes of current desertification trends. Urban and rural populations, now technologically isolated from their environment, need to better understand the dynamic nature of their environment and adapt to these conditions to lessen the human influ-snce on the desertification process. A greater degree of cooperation among diverse entities will be crucial.}, author = {E.L. Fredrickson and Kris Havstad and Richard E. Estell and P.W. Hyder} } @conference {51328, title = {Effect of domestic animals and precipitation levels on the establishment of Lehmann lovegrass (Eragrostis lehmanniana Nees) seedlings}, booktitle = {Mexican Society for Range Management Meeting}, year = {1996}, month = {August 20-23, 19}, address = {Zacatecas, Mexico}, abstract = {

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

}, keywords = {dispersal, domestic animals, Lehmann lovegrass, precipitation, seeds}, author = {Flores, M.A. and E.L. Fredrickson and Pieper, Rex D. and L. W. Murray} } @article {51329, title = {Top-down impacts on creosotebush herbivores in a spatially and temporally complex environment}, journal = {Ecology}, volume = {77}, number = {5}, year = {1996}, note = {//NMSU,USDA//LTER III//}, month = {1996}, pages = {1544-1555}, abstract = {

I studied top-down effects on creosotebush (Larrea tridentata) insect herbivores by protecting them from bird and arthropod predation. The purpose of my study was to investigate experimentally the differential and/or interactive effects of two predator guilds on herbivore densities. I performed my experiments on 24 creosotebushes at each of three sites within the Jornada Long-Term Ecological Research Site in the Chihuahuan Desert of southwestern New Mexico, USA.... I conducted these experiments and censuses in 1993 and again in 1994. In both years the herbivore densities became significantly higher in experimental than in control creosotebushes. The effects of bird and arthropod predation on herbivore densities were additive in 1993, but they were compensatory in 1994.

}, keywords = {arthropod predation, article, articles, avian predation, herbivores, arthropod, herbivory, Larrea, journal, journals, Larrea, herbivores}, doi = {10.2307/2265550 }, url = {files/bibliography/JRN00226.pdf}, author = {Floyd, Ted} } @article {51330, title = {Low-cost seeding practices for restoring desert environments (New Mexico)}, journal = {Restoration and Management Notes}, volume = {14}, year = {1996}, month = {1996}, pages = {72-73}, abstract = {

Over the past 120 years, the grasslands of the northern Chihuahuan desert have been converted to shrublands dominate by species such as mesquite (Prosopis spp.). Unfortunately, attemptsto restore these grasslands have often been unsuccessful despite substantial expenditures of money, labor, and fossil fuels. At the Jornada Experimental Range, we have recently begun to test low-input restoration technologies in an attempt to remedy this situation. One aspect of this program focuses on the use of both water and animals to deposit viable seeds into favorable micro-sites.

}, url = {/files/bibliography/480.pdf}, author = {E.L. Fredrickson and J.R. Barrow and Jeffrey E. Herrick and Kris Havstad and Longland, B.} } @conference {51331, title = {Working together to restore desert rangelands}, booktitle = {International Conference, Society for Ecological Restoration}, year = {1996}, month = {June 17-22, 1996}, pages = {54}, address = {New Brunswick, NJ}, abstract = {We have formed a partnership with local ranchers, environmental groups and government agencies to develop restoration technologies for desertified arid lands. The USDA Agricultural Research Service, Jornada Experimental Range, is a 78,266-hectare desert laboratory located in the northern Chihuahuan Desert. During the last 100 years, much of this area has undergone a transition from desert grasslands to desertified shrublands, a trend that is occurring in most of the world{\textquoteright}s arid lands. In addition to research examining basic ecosystem function, we have set aside 8,259 hectares to be managed by ranchers working with local environmental organizations. Presently, this group is using knowledge of desert ecosystems to create low-cost, restoration technologies for arid lands. Current projects are designed to promote natural restoration processes and include: (1) targeted application or organic waste to enhance soil stability and productivity, (2) placement of watering points that provide a seed source while attracting seed-dispersing wildlife, (3) creation of predator habitat to reduce herbivore pressure during vegetation establishment.}, author = {E.L. Fredrickson and Jeffrey E. Herrick and Kris Havstad and J. A. Winder} } @article {51387, title = {Field simulation of wet and dry years in the Chihuahuan Desert: Soil moisture, N mineralization and ion exchange resin bags}, journal = {Biology and Fertility of Soils}, volume = {20}, year = {1995}, month = {1995}, pages = {137-146}, abstract = {

Irrigation and rain-out shelters were used to simulate precipitation patterns of wet and dry years in the northern Chihuahuan Desert. Irrigation provided approximately double the long-term average monthly precipitation. Rain was excluded during the wet season, July-October, to simulate a dry year. N net mineralization in laboratory incubations was undectable at calculated water potentials less than -1 MPa. With increasing moisture, mineralization gradually rose to the highest observed rates near field capacity. There was no mineralization maximum at moisture contents below field capacity. Irrigation significantly increased the water potential and rainfall exclusion reduced water potentials to less than -8 MPa. The general absence of important irrigation effects may have resulted from the high natural precipitation during the experiment or because irrigation inputs were insufficient to increase microbial activity during very dry periods. Precipitation exclusion reduced ion capture during the warm-wet season. After allowing precipitation inputs to resume, NH4-N capture was increased in the cool-dry seasons of both 1987-1988 and 1988-1989. NH4-N capture more than doubled that predicted from the overall covariance of moisture input and ion capture, suggesting increased availability of N. An unusually hot, dry period in May and June 1989 was followed by a three-to fourfold increase in the warm-wet season N03+N02-N capture compared to 1988. These data suggest that short droughts of about 3 months in length (both simulated and natural) increased N availability relative to moisture availability.

}, keywords = {Analysis of covariance, Chihuahan Desert, Field capacity, Larrea tridentata, Mineralization rate, Precipitation exclusion, simulated rainfall, Soil drying effects}, doi = { 10.1007/BF00336593}, url = {/files/bibliography/441.pdf}, author = {F. M. Fisher and Walter G. Whitford} } @article {51388, title = {Potential toxicity and feed value of onions for sheep}, journal = {Livestock Production Science}, volume = {42}, year = {1995}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1995. (http://www.sciencedirect.com/science/journal/03016226)}, month = {1995}, pages = {45-54}, abstract = {

The feeding, ruminal effects and potential toxicity of cull onions bulbs (Allium cepa) was compared to whole sorghum grain for growing wethers. In Expt. 1, 56 Polypay X Rambouillet wethers (avg. initial BW of 32.7 {\textpm} 0.88 kg) were assigned randomly to one of four dietary treatments (dry matter basis): (1) 50\% whole sorghum grain (CON); (2) 33\% sorghum:17\% onions (17\%); (3) 17\% sorghum:33\% onions (33\%); and (4) 50\% onions (50\%). The remaining 50\% was pelleted alfalfa (19\% CP). All wethers were group fed (seven wethers per pen; two replicates per treatment) for 6 weeks. Weight gain during the trial did not differ (P\> 0.05) among treatments. Packed cell volume tended to be less (P = 0.057) for the 33\% and 50\% onion groups during weeks 1 and 2, and was less (P\< 0.0001) for the same groups during week 3 (34, 33, 29 and 29\% for CON, 17, 33 and 50\%, respectively). Serum lactate dehydrogenase was increased (P\< 0.05) at weeks 3 and 6 in sheep on the 33\% and 50\% onion treatments. During Expt. 2, 15 ruminally cannulated wethers were individually fed diets similar to those Expt. 1, except onions were fed to replace sorghum grain to provide 0, 25 and 50\% of the dietary DM as onions. Ruminal fluid (P\> 0.05) and particulate passage (P\> 0.05) were not altered by feeding onions. Water intake by drinking decreased (P\< 0.0001) as percentage of onions in the diet increased, whereas total water intake (drinking and fed) increased (P\< 0.0001). Effects of onions on volatile fatty acid concentrations and ruminal pH were minimal (P\< 0.05), whereas ruminal ammonia-N concentration was greater (P\< 0.05) in wethers fed onions. We conclude that under conditions similar to those in our study, onions can be fed safely to sheep with weight gains comparable to those from whole sorghum grain.

}, keywords = {Allium cepa, digestion, sheep}, doi = {10.1016/0301-6226(94)00066-G}, url = {/files/bibliography/442.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @article {51442, title = {Effects of plant size and water relations on gas exchange and growth of the desert shrub Larrea tridentata}, journal = {Oecologia}, volume = {97}, year = {1994}, note = {//NMSU//LTER III//}, month = {1994}, pages = {171-178}, abstract = {

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

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

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

}, keywords = {chronic ingestion, ewe lambs, Flourensia cernua, tarbush}, url = {/files/bibliography/421.pdf}, author = {E.L. Fredrickson and Thilsted, J.P. and Richard E. Estell and Kris Havstad} } @article {51478, title = {Reflectance of vegetation and soil in Chihuahuan desert plant communities from ground radiometry using SPOT wavebands}, journal = {Remote Sensing of Environment}, volume = {46}, year = {1993}, note = {//USDA, NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1993}, pages = {291-304}, abstract = {

The spatially averaged reflectance of a partially vegetated land surface can be modeled as an area-weighted mixture of the reflectances of different components or classes of objects (plants, shadow) of the background (soil, grass). We sampled the spectral reflectance of the shaded and unshaded components of Chihuahuan desert plant communities (shrubs, soil, subshrubs, and perennial grasses) in the SPOT wavebands using a hand-held radiometer. WE examined the mean reflectance differences between components to evaluate their spectral separability. Shrub canopy and shaded components have similar reflectance in the visible wavebands. However, in the near-infrared band, which is strongly scattered by green plant canopies, the shaded canopy and shaded background components were similar to each other and lower than either sunlit background or sunlit canopy. When reflectance measurements were transformed to normalized ratio (NDVI, SAVI) and orthogonal green vegetation indices, the shaded and sunlit portions of each component (canopy and soil) were similar, but the shaded components were intermediate between their sunlit counterparts. Different soil types and plant species with different life forms (e.g., shrubs, grasses) and phenologies exhibited different reflectance characteristics. However, the broadband reflectances of the three dominant shrub species were similar at the end of the growing season, in spite of their differences in morphology.

}, keywords = {article, articles, Bouteloua, remote sensing, Flourensia, remote sensing, journal, journals, Larrea, remote sensing, model, landscape, Li-strahler, model, Li-strahler, Prosopis, remote sensing, radiometry, remote sensing, Bouteloua, remote sensing, Flourensia, remote sensing, Larrea, remote sensing, Prosopis, remote sensing, soil reflectance, remote sensing, soils, remote sensing, vegetation reflectance, soil, remote sensing}, doi = {10.1016/0034-4257(93)90049-4}, url = {files/bibliography/JRN00171.pdf}, author = {Janet Franklin and J. Duncan and Turner, Debra L.} } @conference {51482, title = {Animal and shrub interactions: Developing a tarbush model}, booktitle = {8th Wildland Shrub and Arid Land Restoration Symposium}, year = {1993}, month = {1993}, pages = {Abstract 7}, address = {Las Vegas, NV}, abstract = {Large areas of the Chihuahuan Desert are undergoing a transition from semiarid grassland to desert scrub. The role of mammalian herbivores in mediating this transition has been suggested but has not been adequately described. A better understanding of plant-animal interactions may assist in developing animal-based technologies to increase shrub use while mediating vegetational change. Tarbush (Flourensia cernua), an aromatic shrub rapidly invading productive range sites, was used as a model to examine the influence of leaf surface compounds on the use of tarbush by domestic sheep. Additional studies also were designed to examine the digestive and physiological consequences of ingestion of tarbush leaves. Results from these studies indicate: (1) dietary preference is influenced by either epicuticular waxes or a component of the wax, (2) intraspecific variation of epicuticular chemistry varies both temporally and spatially, (3) nutrient concentrations are similar to alfalfa, (4) ruminal fermentation patterns are altered by inclusion of tarbush in grass diets, and (5) toxicosis can result from chronic consumption of tarbush leaves. Interpretation of these data suggest controlled use of tarbush by sheep is possible, but use of sheep to mediate desired vegetational change may be limited.}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad} } @conference {51480, title = {Effect of chronic ingestion of tarbush (Flourensia cernua) on the serum chemistry, occult blood and histopathology of ewe lambs}, booktitle = {Annual Meeting, Society for Range Management}, year = {1993}, month = {1993}, pages = {130}, abstract = {

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

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

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

}, doi = {10.1016/0377-8401(93)90149-E}, url = {/files/bibliography/402.pdf}, author = {E.L. Fredrickson and Galyean, M.L. and Cheema, A.U. and Beaty, R. and Byrum, G.} } @article {51479, title = {Influence of ruminally dispensed monensin and forage maturity on intake and digestion}, journal = {Journal of Range Management}, volume = {46}, number = {3}, year = {1993}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1993}, pages = {214-220}, abstract = {

Eight ruminally cannulated crossbred steers (average weight 336 kg) grazing native blue grama (Bouteloua gracilis\  [H.B.K.]) rangeland were used in a repeated measures design to evaluate effects of monensin ruminal delivery devices (MRDD) and forage phenology on ruminal digestion.\  Three periods were assessed: mid-August (Aug.), early October (Oct.), and mid-November (Nov.).\  One MRDD was placed in the reticulum of 4 steers via the ruminal cannula 21 days before each period.\  Intake was estimated using total fecal collections.\  Diet samples were collected using 3 esophogeally fistulated steers. Ruminal fill was measured by ruminal evacuation; rate and extent of in situ ruminal neutral detergent fiber disappearance were estimated before ruminal evacuations.\  Ruminal passage rates, retention time, and apparent total tract organic matter digestibility were estimated using indigestible neutral detergent fiber.\  In vitro organic matter disappearance of esophageal masticate did not differ (P\>.05) in Aug. and Oct. (average of 53.7\%), but declined (P\<.05) in Nov. (48.7\%), whereas organic matter digestibility was greater (P\<.10) in Aug. (62.3\%) than in either Oct. (55.2\%) or Nov. (53.9\%).\  Release of monensin from the bolus (68 mg day-1) was less than expected (100 mg day-1).\  Intake, organic matter digestibility, ruminal passage rates, retention time, pH, and ammonia were not affected (P\>.10) by MRDD.\  In situ neutral detergent fiber disappearance at 96 hours was decreased (P\<.10) by MRDD (68 vs 65\% for control and MRDD, respectively).\  As the grazing season progressed, intake declined (P\<.10), whereas ruminal fill and retention time increased (P\<.05), and passage rate of indigestible neutral detergent fiber decreased (P\<.05). At 48 hours in situ neutral detergent fiber was greatest (P\<.05) in Aug. and least (P\<.05) in Nov.

}, keywords = {beef, cattle, digestion, forage quality, rangeland}, url = {/files/bibliography/401.pdf}, author = {E.L. Fredrickson and Galyean, M.L. and Branine, M.E. and Sowell, B.F.} } @conference {51481, title = {Use of domestic animals as biological control agents of desert shrubs: Problems and promise}, booktitle = {4th Symposium on the Chihuahuan Desert Region: US and Mexico}, year = {1993}, month = {1993}, pages = {11}, abstract = {Inseparable anthropogenic and nonanthropogenic factors have altered the dynamics and form of the Chihuahuan Desert. This alteration is characterized by replacement of desert grasslands with shrub species. When this change is viewed as deleterious, few remedial technologies are available either because of economics or potential ecological constraints. In conjunction with skillful management, domestic animals may provide an accessible bioremediation tool that provides additional nutritional and economic benefits. Attempts to use domestic animals to facilitate vegetational change have been successful; however, failures often occur because of animal rejection of target plants. Aspects of animal preference, plant palatability, and plant toxicity are causes of this rejection that may be biochemically mediated. Focusing on carbon-based phytochemicals within tarbush (Flourensia cernua), we have documented substantial temporal and spatial variability in plant phytochemistry while identifying compounds suspected to influence plant palatability. Furthermore, we have observed considerable variation in animal preference for tarbush within and among animal species. Although chemo- and electromagnetic receptors are generally considered to affect animal preference, we provide evidence that preference is also affected by visceral afferents which signify hepatic toxicosis. Examining plant-animal interactions from a biochemical perspective will enhance our understanding of vegetation change and development of potential restorative technologies.}, keywords = {biological control agents, desert shrubs, domestic animals}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad} } @mastersthesis {51484, title = {Grazing influences on watering point vegetation in the Chihuahuan desert}, year = {1993}, note = {//??//NONE//}, month = {1993}, pages = {62}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle grazing, watering point vegetation, cattle, management, watering point vegetation, dissertation, dissertations, theses, thesis}, author = {Fusco, Michael J.} } @article {51520, title = {The application of a geometric optical canopy reflectance model to semiarid shrub vegetation}, journal = {IEEE Transactions on Geoscience and Remote Sensing}, volume = {30}, year = {1992}, note = {//NMSU,USDA//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1992}, pages = {293-301}, abstract = {

The Li-Strahler [7] canopy model was tested, using SPOT HRV XS imagery, for semiarid shrub vegetation, based on 26 small (1-ha) sites in five classes of shrub vegetation, two dominated by tarbush (Flourensia cernua), one by creosote bush (Larrea tridentata), and two by mesquite (Prosopis glandulosa). The model was driven by reflectance values derived from June and September imagery. While predictions of crown size and density for individual sites had a large average error of 35\%, the predictions of shrub size and density were reasonably accurate when grouped by shrub class. The aggregated predictions for a number of stands within a class were accurate to within one or two standard errors of the observed average value. Accuracy was highest but predictions were biased for some classes (size was underestimated) when the nonrandom shrub pattern was characterized for the class based on the average coefficient of determination of density. Results based on June data were not better than September because the hypothesized lower background "noise" (e.g., less green herbaceous cover that could be confused with shrub cover in the simple reflectance model) was not observed in June data. This could have been due to the poor radiometric quality of the June image.

}, keywords = {article, articles, journal, journals, model, shrub canopy reflectance, remote sensing,reflectance model}, doi = {10.1109/36.134079}, url = {files/bibliography/JRN00163.pdf}, author = {Janet Franklin and Turner, Debra L.} } @article {51521, title = {Feeding cull onions: The {\textquoteright}ins{\textquoteright} and {\textquoteright}outs{\textquoteright}}, journal = {Sheep Magazine}, year = {1992}, month = {October 1, 1992}, pages = {17,32}, abstract = {

The most costly aspect of any sheep operation is the cost associated with feed. Because of this, a resourceful operator is always looking for ways to cut feed costs as a means of increasing profits. One potential source of low cost, good quality, feed is cull onions.

}, url = {/files/bibliography/383.pdf}, author = {E.L. Fredrickson} } @article {51522, title = {Feeding cull onions to sheep}, journal = {Ranch Magazine}, year = {1992}, month = {October 1, 1992}, pages = {44}, abstract = {Several years ago during a visit to the Las Cruces city landfill, we saw a small mountain of cull onions with several pickups parked around it. People were climbing over the pile looking for the best onions to load in their pickups to either eat or sell. While watching the people sort through the onions we wondered if we could use onions as a livestock feed. Sometime later we searched various journals to learn what is currently known about feeding cull onions to livestock. To our surprise, there was very little information. Most all the articles available only described a condition termed "oxlion poisoning," a condition where sulfur compounds in onions cause red blood cells to loose their ability to carry oxygen and eventually the red blood cells die. Despite these reports in the literature, we knew of a few sheep producers who were feeding cull onions. It became obvious to us that research designed to determine the amount of onions that could safely be fed to sheep might be useful to sheep producers and onion growers alike. Onions are potentially an inexpensive feed. Also, cull onions reentering the market place negatively affect market demand for onions and onion prices. With aid from the New Mexico Dry Onion Commission, we completed two studies using sheep.}, keywords = {cull onions, inexpensive feed, livestock feed, oxlion poisoning, sheep}, url = {/files/bibliography/384.pdf}, author = {E.L. Fredrickson and Shupe, W. Larry} } @proceedings {51563, title = {Effects of monensin supplementation on grazing beef cattle}, volume = {70 (12)}, year = {1991}, month = {1991}, pages = {6-7}, author = {E.L. Fredrickson and Galyean, M.L.} } @article {51564, title = {Grazing behavior of rangeland beef cattle differing in biological type}, journal = {Journal of Animal Science}, volume = {69}, year = {1991}, month = {1991}, pages = {1435-1442}, abstract = {

Grazing behavior exhibited by different biological types (breed groups) of lactating beef cows was evaluated during the summers of 1985 (Trial 1) and 1986 (Trial 2). Animals grazed native Montana foothill grassland. In Trial 1, breed groups consisted of Hereford (BM, 50\% Angus-50\% Hereford (AH), 50\% Simmental-50\% Hereford (SH), and 75\% Simmental-25\% Hereford (3S1H) with six cows per breed group. Daily grazing hours were 11.8 {\textpm} .2, 12.3 {\textpm} .2, 11.6 {\textpm} .2, and 11.6 {\textpm} .5 h/d for HH, AH, SH, and 3S1H, respectively. There was a tendency for AH cows to graze longer than HH and SH cows (P = .10). Bite rates were 52.7 {\textpm} 1.5, 56.2 {\textpm} 1.5, 53.2 {\textpm} 1.4, and 59.0 {\textpm} 1.6 bites/min for HH, AH, SH, and 3S1H, respectively. The AH and 3S1H cows had higher bite rates (P \< .05) than the HH and SH cows. Means for distance traveled were 3.1 {\textpm} .2, 3.4 {\textpm} .2, 4.0 {\textpm} .2, and 2.8 {\textpm} .2 km/d for HH, AH, SH and 3S1H, respectively. The SH cows tended to travel farther (P \< .10) than cows of other breed groups. The AH traveled farther than the 3S1H but did not differ from the HH. In Trial 2, breed groups were Hereford (HH), Tarentaise-Hereford (TH), Tarentaise-Simmental-Hereford (T(SH)), and Charolais-Simmental-Hereford(C(SH)); each group included six lactating cows. Means for bite rate were 56.9 {\textpm} 1.1, 58.7 {\textpm} 1.1, 60.9 {\textpm} 1.0, and 59.0 {\textpm} 1.1 bites/min for HH, TH, T(SH), and C(SH), respectively. The T(SH) cows had a higher bite rate than the RH cows (P \< .10), but bite rates did not differ between T(SH) and TH or C(SH) cows. Breed group means were not different (P \> .10) for grazing time and distance traveled. Thus, bite rate was the only behavioral expression that was consistently different among breed groups and may be a response that allows different biological types to achieve different levels of intake.

}, keywords = {beef cattle, breeds, grazing behavior, groups, rangelands}, url = {/files/bibliography/708.pdf}, author = {Funston, R.N. and Kress, D.D. and Kris Havstad and D. E. Doornbos} } @mastersthesis {51611, title = {Diet botanical composition and fecal chemical indices of cows and steers on semidesert rangleland}, year = {1990}, note = {//??//NONE//}, month = {1990}, pages = {79}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, keywords = {cattle, diet, cattle,fecal chemical indices, dissertation, dissertations, theses, thesis}, author = {Ferrando, Carlos Alberto} } @article {51612, title = {Decomposition and soil nitrogen availability in Chihuahuan Desert field microcosms}, journal = {Soil Biology and Biochemistry}, volume = {22}, year = {1990}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1990}, pages = {241-249}, abstract = {

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

}, keywords = {article, articles, decomposition, soil biota, journal, journals, soil bacteria, soil biota, soil microcosm, soil nitrogen, soil yeast, soil, litter decomposition, soil, nematode population, soil, root decomposition}, doi = {10.1016/0038-0717(90)90093-F}, url = {files/bibliography/JRN00118.pdf}, author = {F. M. Fisher and D. W. Freckman and Walter G. Whitford} } @article {51657, title = {Containment of free-ranging goats using pulsed-radio-wave-activated shock collars}, journal = {Applied Animal Behavior Science}, volume = {23}, year = {1989}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1989. (http://www.sciencedirect.com/science/journal/01681591)}, month = {1989}, pages = {165-171}, abstract = {

Goats (Caprahircus) are useful for brush and weed control. Their usefulness would be enhanced if their distribution on grazing land could be controlled without herders or permanent fencing. The feasibility of using electric shock collars to restrict the range of grazing goats was evaluated. Electric shock collars developed for canine control were tested as an alternative method for unattended containment. Shock collars effectively contained goats within the designated test area. Goats not wearing the shock collars remained close to the collared goats due to herd instinct and, thus, also remained within the test area. Preliminary results indicate that the non-visual fence may make it feasible to develop commercial weed-grazing goat herds restricted to weed infestations by electric collars.

}, doi = {10.1016/0168-1591(89)90016-6}, url = {/files/bibliography/700.pdf}, author = {Philip A. Fay and McElligott, V.T. and Kris Havstad} } @article {51658, title = {Plant-feeding nematodes in deep-rooting desert ecosystems}, journal = {Ecology}, volume = {70}, number = {6}, year = {1989}, note = {//NMSU,USDA//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {1665-1678}, abstract = {

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

}, keywords = {article, articles, creosotebush, nemotode, deep soil, herbivory, journal, journals, mesquite, nematode, nematode, arroyo, nematode, creosotebush, nematode, dune, nematode, grassland, nematode, plant-feeding, nematode, playa, roots, nematodes, soil fauna, deep-rooted plants, soil,nematodes}, doi = {10.2307/1938101}, url = {files/bibliography/JRN00103.pdf}, author = {D. W. Freckman and R. A. Virginia} } @article {51712, title = {Seasonal food habits of blacktailed jackrabbits (Lepus californicus) in southern New Mexico}, journal = {The Southwestern Naturalist}, volume = {33}, number = {3}, year = {1988}, note = {//NMSU//NONE//}, month = {1988}, pages = {367-370}, abstract = {Diet of the blacktailed jackrabbit (Lepus californicus) varies seasonally in response to forage maturity and availability (Vorhies and Taylor, 1933). Grasses and forbs tend to dominate the diet in early spring and summer (Flinders and Hansen, 1972). Shrubs become more important in late fall and winter (Hansen and Flinders, 1969)....In spite of the large number of studies on diets of jackrabbit, only those of Dabo et al (1982) and Griffing and Davis (1976) were conducted in southern New Mexico, and they studied diets only for the summer months. The major objective of this study was to examine seasonal patterns of dietary composition of diets of blacktailed jackrabbits.}, keywords = {article, articles, food habits,Lepus, journal, journals, lagomorph,food habits, Lepus, food habits}, author = {Fatehi, Mohammad and Pieper, Rex D. and Reldon F. Beck} } @article {51713, title = {Water and nitrogen effects on growth and allocation patterns of creosotebush in the northern Chihuahuan Desert}, journal = {Journal of Range Management}, volume = {41}, number = {5}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {387-391}, abstract = {

A field experiment using 2 patterns of irrigation and 1 level of nitrogen fertilizer (10 g-N m-2) was conducted in order to discern water and nitrogen interactions that may control production of creosotebush (Larrea tridentata (D.C.) Cov.). The 2 patterns of irrigation simulated precipitation from small, frequent events (6 mm water added weekly) or large, infrequent events (25 mm water added monthly). Understnaing the factors controlling the production of this rangeland shrub may aid in the development of strategies for management. Vegatative growth occurred mostly during March-May (spring) and August-October (summer-fall). Fruit production occurred mainly in the spring and root growth ocurred mainly in the summer-fall. Irrigation increased vegetative growth and decreased fruit produciton. Responses to irrigation were greater during summer-fall than in the spring. Small, frequent water additions caused larger increases in vegetative plus fruit growth than did large, infrequent water additions. Nitrogen fertilization increased the growth of both vegetation and fruit in irrigated and unirrigated plots. Stem mortality and root growth were not significantly affected by irrigation or nitrogen fertilizer. These results suggest that creosotebush production is limited by both soil moisture and nitrogen availability and that temporal patterns of rainfall may be as important as total amounts.

}, keywords = {article, articles, journal, journals, Larrea,morphology, Larrea,nitrogen amendment, Larrea,phenology, Larrea,rainfall simulation, Larrea,reproduction, nitrogen amendment,Larrea, rainfall simulation,Larrea}, doi = {10.2307/3899572 }, url = {files/bibliography/JRN00088.pdf}, author = {F. M. Fisher and J. C. Zak and Gary L. Cunningham and Walter G. Whitford} } @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 {51768, title = {Accuracy of soil thermocouple hygrometer measurements in desert ecosystems}, journal = {Ecology}, volume = {68}, number = {4}, year = {1987}, note = {//NMSU//LTER I//}, month = {1987}, pages = {1121-1124}, abstract = {

The use of thermocouples in studies of soil and plant water relations began in the 1950{\textquoteright}s (Spanner 1951, Monteith and Owen 1958, Richards and Ogata 1958, Savage and Cass 1984). Initially, thermocouples were used only in laboratory studies because precise temperature control was thought to be essential for accurate measurements (Kramer 1972). Field applications began after Rawlins and Dalton (1967) and Wiebe et al. (1970) demonstrated that certain corrections eliminated the need for precise control. With the advent of commercial availability, thermocouples have been widely used by plant ecologists (see Turner and Kramer 1980 for examples). Despite their extensive use, many investigators are distrustful of data obtained with soil thermocouples. The prevelence of this distrust, although not expressed in the literature, is commonly expressed in discussions among scientists who have had field experience with thermocouples. We compared soil water potential data obtained with soil thermocouples to measurements ofpredawn xylem sap potential of desert shrubs (Scholander et al. 1965, Waring and Cleary 1967). The null hypothesis tested was that predawn xylem sap potentials would not differ significantly from soil water potential values measured with soil thermocouples in the dew point mode (hygrometers), because xylem sap potentials at that time are in equilibrium with rhizosphere water potential (Ritchie and Hinkley 1975).

}, keywords = {article, articles, Gutierrezia,xylem sap potential, hygrometer, soil thermocouple, journal, journals, Larrea,xylem sap potential, soil water potential,technique, soil, thermocouple hygrometer, technique,soil thermocouple hygrometer, thermocouple, accuracy}, doi = {10.2307/1938388 }, url = {files/bibliography/JRN00050.pdf}, author = {P. J. Fonteyn and W. H. Schlesinger and G. M. Marion} } @article {51769, title = {Effect of irrigation on nematode population dynamics and activity in desert soils}, journal = {Biology and Fertility of Soils}, volume = {3}, year = {1987}, note = {//NMSU//LTER I//}, month = {1987}, pages = {3-10}, abstract = {

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

}, keywords = {article, articles, irrigation,SEE , journal, journals, nematode community, nematode, rainfall simulation, nematode,anhydrobiosis, rainfall simulation,nematode population}, doi = {10.1007/BF00260571}, url = {files/bibliography/JRN00054.pdf}, author = {D. W. Freckman and Walter G. Whitford and Yosef Steinberger} } @mastersthesis {51819, title = {Comparative seasonal food habits of black-tailed jackrabbits and cattle on semidesert rangeland}, year = {1986}, note = {//NMSU//NONE//}, month = {1986}, pages = {68}, school = {New Mexico State University}, type = {Ph.D. Dissertationpp}, address = {Las Cruces, New Mexico}, abstract = {Seasonal diets of black-tailed jackrabbit (Lepus Californicus) and dietary overlap between black-tailed jackrabbits and cattle were studied from May 1984 to May 1985 in three vegetation types in southwestern New Mexico. A microhistological technique was used to identify botanical composition of fecal samples....Although jackrabbit and cattle ate some of the same species, they did not eat them in similar proportions. Food overlap was slight during winter, and 36\% in spring. The diet overlap bwtween these animals was greater during early spring when both animal species preferred green forage.}, keywords = {cattle, food habit \& rabbits, cattle,food habits, dissertation, dissertations, food habits,cattle, food habits,Lepus, lagomorph, Lepus, Lepus, food habits, mammal, SEE , rabbit, SEE , theses, thesis}, author = {Fatehi, Mohammad} } @article {51820, title = {Abundance, distribution, biomass and energetics of soil nematodes in a northern Mojave Desert ecosystem}, journal = {Pedobiologia}, volume = {29}, year = {1986}, note = {//OTHER//??//}, month = {1986}, pages = {129-142}, keywords = {article, articles, journal, journals, nematode, abundance, nematode, biomass, nematode, distribution, nematode,energetics, soil nematode, SEE }, author = {D. W. Freckman and Mankau, R.} } @article {51878, title = {Host plant ovipositional preferences and usage by Oecleus nolinus (Homoptera: Cixiidae)}, journal = {The Southwestern Naturalist}, volume = {30}, number = {4}, year = {1985}, note = {//NMSU//NONE//}, month = {1985}, pages = {610-611}, abstract = {

During May and June , 1979, we observed large numbers of O. nolinus at the Jornada Experimental Range, 60 km NNE of Las Cruces, Dona Ana Co., New Mexico. They used three plant species (Yucca baccata, Y. elata and Dasyliron wheeleri) as ovipostional sites. Dasyliron wheeleri is an apparent new host for O. nolinus. Townsend (Psyche 6:353-354, 1928) recorded an Oecleus, probably O. nolinus but recorded as O. decens, ovipositing on Yucca angustifolia (=Y. elata?) and Y. macrocarpa (=Y. baccata?) in southern New Mexico.

}, keywords = {article, articles, Dasylirion,ovipositional site, insect, Oecleus, invertebrate, Homoptera, journal, journals, Oecleus,ovipositional sites, Oecleus,reproduction strategy, plant, Dasylirion, plant, Yucca, Yucca,ovipositional site}, url = {files/bibliography/85-SWNat-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @article {51877, title = {Structure and organization of a winter community of cavity-inhabiting, web-building spiders (Pholocidae and Theridiidae) in a Chihuahuan Desert habitat}, journal = {Journal of Arid Environments}, volume = {8}, year = {1985}, note = {//NMSU//US-IBP//}, month = {1985}, pages = {57-65}, abstract = {

Populations of Chihuahuan Desert spiders that construct webs in naturally occurring cavities were followed over a 20-week-period with modified pitfall traps. Of the three species studied, Psilochorus imitatus (Pholocidae) was the most abundant, followed in order by Artema atlanta (Pholocidae) and Latroductus hesperus (Theridiidae). Canonical correlation analysis indicated a strong dependence of L. hesperus upon soil temperatures. A principal axis factor analysis explained 87 per cent of the variance in the spider-weather-habitat aspect system with five common factors. This model also gave a good fit to all monitored variables. This analysis demonstrated the importance of habitat aspect upon spider distributions, and allowed an examination of the partitioning of niche space by the three species. Experimental laboratory manipulations suggested that groups of A. atlanta can behaviorally dominate solitary L. hesperus females by restricting orb web construction, and suggested that patterns observed in the field may be shaped by interspecific competition.

}, keywords = {article, articles, journal, journals, spider, Artema, spider, cavity-inhabiting, spider, Latrodectus, spider, Psilochorus, spider, web-building, spider,community structure}, doi = {10.1016/S0140-1963(18)31337-5}, url = {files/bibliography/85-JrnlofAridEnvn-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @article {51904, title = {Coordinated prey capture by Novomessor cockerelli (Hymenoptera: Formicidae)}, journal = {New York Entomological Society}, volume = {91}, number = {4}, year = {1984}, note = {//NMSU//NONE//}, month = {1984}, pages = {328-332}, abstract = {

Novomessor cockerelli uses coordinated behavior to subdue large orthopteran prey. When a partially disabled grasshopper is encountered, the first worker finding it mounts the dorsum of the grasshopper and clamps its mandibles over the wings, thus preventing escape by flight. Workers which arrive subsequently systematically remove or subjugate additional appendages. Behavioral coordination allows N. cockerelli to efficiently exploit large orthopterna prey which would otherwise escape if workers attempted to capture these individually.

}, keywords = {ant, prey capture, ant,Novomessor, article, articles, invertebrate,also SEE , journal, journals, Novomessor,foraging strategy, Novomessor, Novomessor,prey capture, Orthoptera, Novomessor prey}, url = {files/bibliography/84-NYEntmlgclScty-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @article {51939, title = {Pre-dispersal seed feeding insects of a desert legume, Astragalus nutallianus}, journal = {The Southwestern Naturalist}, volume = {28}, number = {4}, year = {1983}, note = {//NMSU//NONE//}, month = {1983}, pages = {466-469}, abstract = {

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

}, keywords = {article, articles, Astragalus,seed feeding insects, granivore, Astragalus, insect, foraging stategy,seed feeding, insect, seed feeding, journal, journals, plant, Astragalus, plant, locoweed, Astragalus}, url = {files/bibliography/83-SWNat-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @article {51940, title = {Some relationships between enviornmental relaibility and seed dormancy in desert annual plants}, journal = {Journal of Ecology}, volume = {71}, year = {1983}, note = {//LOCAL//NONE//}, month = {1983}, pages = {211-217}, abstract = {(1) There are two groups of annual species that grow in the northern Chihuahuan Desert of North America. Plants in one group germinate and complete their life cycle in late summer. Those in the other germinate in winter or early spring and complete their life cycle in the spring. The late summer season in characterized by abundant and reliable rain, while the winter-spring season has less abundant and less reliable rain. (2) Several theoretical models have been suggested which predict that annual plants from uncertain environments may or may not have evolved innate dormancy to offset the possibility of population extinction due to complete germination followed by complete mortality under severely unfavourable conditions. (3) We have tested these models with a comparative experiment examining the germination responses of seeds collected from an annual species which grows during the more reliable summer season and two annual species which grow during the less reliable winter-spring season. (4) The summer annual species does not have a genetically fixed innate dormancy, but the two winter annual species apparently have evolved a genetically controlled innate dormancy. (5) All three annual species exhibited environmentally-controlled seed dormancy with respect to amount of rainfall. Seeds germinated only when the equivalent of more than 10 mm of rain fell. Above 15 mm of simulated rain, germination was positively correlated with increasing amount of rain in all three species. (6) The importance of innate dormancy, water-controlled dormancy, and seed dispersal to the long-term survival of these species is discussed.}, keywords = {annual plant, germination, annual plant, rainfall, article, articles, journal, journals, Lappula, germination, Lepidium, germination, Pectis, germination, seed, germination}, author = {K.E. Freas and P. R. Kemp} } @article {52002, title = {Floral visitation by Chihuahuan Desert ants}, journal = {Journal of Natural History}, volume = {16}, year = {1982}, note = {//NMSU//NONE//}, month = {1982}, pages = {879-881}, abstract = {

Experimental and observational tests with tropical lowland plant species and ants have generally rejected Janzen\&$\#$39;s (1977) hypothesis of deterrent chemicals in floral nectars.... Here we address the following two questions for desert plants: (1) do ants naturally visit desert flowers for floral nectar:, and (2) are floral nectars of desert plants repellent to ants?

}, keywords = {ant, floral nectar, ant, floral visitation, ant,foraging strategy, article, articles, journal, journals}, doi = {10.1080/00222938200770701}, url = {files/bibliography/82-JrnofNatHistry-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @booklet {52003, title = {Causes and Effects of Stratosphereic Ozone Depletion: An Update}, year = {1982}, month = {1982}, pages = {352 pp}, publisher = {National Academies Press}, address = {Washington, D.C.}, keywords = {causes and effects, stratosphereic ozone depletion}, url = {http://www.nap.edu/openbook.php?record_id=319\&page=R1}, author = {Friend, J.P. and Henderson, M.M. and Jagger, J. and Klein, R.M. and Parrish, J.A. and Seliger, H.H. and Setlow, R.B. and Sisson, W.B.} } @mastersthesis {52030, title = {Systematic and ecological studies of the Apodemia mormo complex (Lepidoptera: Riodinidae) in southern Arizona and southern New Mexico}, year = {1981}, note = {//LOCAL//NONE//}, month = {1981}, pages = {83}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {Population samples of the polytypic riodinid butterfly Apodemia mormo from the southwestern United States and northern Mexico were studied to determine the distribution of phenotypic variation. In all, 1,813 specimens from 103 locales were examined; 464 specimens were used in cluster and discriminant analysis procedures. The study revealed a highly diverse assemblage consisting of latitudinal and attitudinal clines, polytopic races, complex intergrade zones, and extensive individual variation. Variation present in the study area (southern Arizona to western Texas) was compared with variation patterns on California, Colorado, and Baja California populations. Intergrade zones are interpreted as possibly the result of local intermediacy in selective factors rather than physical contact of adjoining races. Gene flow appears to be greatly restricted among neighboring populations in the region of intergradation. Variation in A. mormo may be determined by such factors as thermoregulation, cryptic coloration, and foodplant associations. The role of historical selective factors is also acknowledged, as is the possibly nonadaptative nature of the color patterns due to pleiotropy. The polytopic nature of the insect, in which distant populations produce the some phenotypes, is evidence against the complex consisting of more than one species throughout most of the range. In a few cases, it is possible that local temporally or ecologically isolated populations (such as those seperated by foodplant preference) may be reproductively isolated species or sibling species.}, keywords = {Apodemia,ecology of, Apodemia,phenotypic variation, butterfly,SEE , dissertation, dissertations, invertebrate, Apodemia,systematics, Lepidoptera,Apodemia, theses, thesis}, author = {Gregory S. Forbes} } @article {52031, title = {Mating behavior of Polyphylla diffracta (Coleoptera: Scarabaeidae)}, journal = {The Southwestern Naturalist}, volume = {26}, number = {2}, year = {1981}, note = {//LOCAL//NONE//}, month = {1981}, pages = {215-216}, abstract = {

On 26 Jul. 1969, imagos were observed emerging form an open park near Las Cruces, New Mexico, between 1800 and 2000 h (MST). Males were flying in a zig-zag pattern, 10 to 50 cm above ground level, with their lamellate antennae extended. In three of the 22 copulations observed, males helped the female to dig her way out of the soil. Females emerged briefly, mated, than returned to their emergence burrows and disappeared. Only males were captured at lights, suggesting that females emerge only to mate. On 16 occasions, more than one male was attracted to the emergence hole, resulting in jostling for copulatory positions. After on male successfully engaged the female genitalia, the other males dispersed. Three newly emerging females were captured before copulation and placed in small screen cages. When placed on the ground, each of these cages attracted a minimum of five males within a 5-min time period. Males also landed and investigated emergence holes into which newly mated females had returned. All of these observations support the presence of sex pheromones in Polyphylla diffracta, and suggest that the females mate only once.

}, keywords = {article, articles, insect, Polyphylla, journal, journals, Polyphylla,mating behavior}, doi = {10.2307/3671129 }, url = {files/bibliography/81-SWNtrlt-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @proceedings {52084, title = {Behavioral and population ecology of a major Yucca herbivore}, year = {1980}, note = {//NMSU//NONE//ProCite field[6]: In}, month = {1980}, pages = {91-113}, publisher = {Centro de Investigacion en Quimica Aplicada}, abstract = {The mirid Halticoma valida Reuter was found to be the dominant herbivore of Yucca in southern New Mexico. Although populations were very high on Y. baccata, developmental rates were faster on Y. elata. Populations on both species of Yucca declined sharply after flowering and fruiting, and subsequent visitations by ants. Laboratory experiments confirmed the preference for the lower density Y. baccata. Feeding bouts were longer on y. baccata and Y. torreyi than on Y. elata, as well as interference competition between the developing instars for feeding sites, due to high populations supported on these species. Extract of Y baccata and Y. torreyi produced significantly greater aggregations than extracts of Y. elata. The effects of leaf surface area, water balance, and chemical and physical characteristics of Yucca on the feeding and aggregating of H. valida is discussed.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, Halticoma,behavior, Halticoma,population ecology, insect herbivory,Yucca, insect,behavior, insect,Halticoma, insect,population ecology, invertebrate, also SEE , population ecology, Yucca herbivory, proceeding, proceedings, Yucca, herbivory}, author = {Harold G. Fowler} } @article {52083, title = {Termites, microarthropods and the decomposition of senescent and fresh creosotebush (Larrea tridentata) leaf litter}, journal = {Journal of Arid Environments}, volume = {3}, year = {1980}, note = {//NMSU//US-IBP//}, month = {1980}, pages = {63-68}, abstract = {

Weight loss of fresh and senescent creosotebush (Larrea tridentata) leaves was studied during September and October, which is normally the peak of surface feeding by subterranean termites. Termites built galleries in 87.5 per cent of the bags of senescent litter and in 12.5 per cent of the bags of fresh litter. There was no significant weight loss attributable to termites. Senescent litter lost more weight than fresh litter but this was reversed during a period of abnormally high rainfall. It is suggested that this results from the presence of allelochemics in fresh litter and leaching of these compounds with high precipitation.

}, keywords = {article, articles, decomposition, Larrea litter, decomposition,microarthropod, decomposition,termite, Gnathemitermes, Larrea decomposition, journal, journals, litter,Larrea decomposition, microarthropod, Larrea decomposition, termite,Larrea decomposition}, doi = {10.1016/S0140-1963(18)31675-6}, url = {files/bibliography/80-JnlArdEnvnmts-Whitford.pdf}, author = {Harold G. Fowler and Walter G. Whitford} } @mastersthesis {52151, title = {Reproductive strategies in desert annuals: test of a fixed germination hypothesis}, year = {1978}, note = {//LOCAL//NONE//}, month = {1978}, pages = {23}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {In order to optimize reproduction in unpredictable environments, Cohen has hypothesized that desert annual plant populations maintain a constant proportion of germinating seeds. The two mechanisms by which a population might maintain this germination proportion, constant at the level of the individual, or a constant population mean, have been investigated through a series of germination tests with the annual species, Pectis angustifolia Torr. (Lemonweed). Results indicate that neither of these mechanisms function to maintain a constant germination proportion. Rather, the data suggest an alternative optimal reproductive strategy by which germination proportion increases in response to increased precipitation.}, keywords = {annual plant, germination, dissertation, dissertations, germination, annual plant, reproduction, annual plant, theses, thesis}, author = {K.E. Freas} } @article {52181, title = {Distribution and trophic structure of nematodes in desert soils}, journal = {Ecological Bulletin (Stockholm)}, volume = {25}, year = {1977}, note = {//??//??//}, month = {1977}, pages = {511-574}, keywords = {article, articles, journal, journals, nematode,distribution, nematode,trophic structure}, author = {D. W. Freckman and Mankau, R.} } @article {52301, title = {Separation of treatments within a plant community based on statistical analysis of plant structural dynamics}, year = {1973}, note = {//??//US-IBP//}, month = {1973}, institution = {Colorado State University}, address = {Ft. Collins, Colorado}, keywords = {book, books, chapter, chapters, plant community, plant structural dynamics, report, reports}, isbn = {Preprint 65}, author = {Francis, R. C. and M. Campion} } @article {52332, title = {Statistical analysis of intraseasonal herbage dynamics in a variety of grassland communities}, year = {1972}, note = {//??//US-IBP//}, month = {1972}, institution = {Colorado State University}, address = {Ft. Collins, Colorado}, keywords = {book, books, chapter, chapters, grassland community,herbage dynamics, report, reports}, isbn = {Technical Report 141}, author = {Francis, R. C. and M. Campion} } @article {52333, title = {Pollen study of some Holocene alluvial deposits in Dona Ana County, southern New Mexico}, journal = {The Texas Journal of Science}, volume = {24}, year = {1972}, note = {//LOCAL//NONE//}, month = {1972}, pages = {203-220}, abstract = {The fossil pollen spectra of 3 radiocarbon dated alluvial deposits at Gardner Spring, New Mexico were studied. The oldest of these sections spans the time from 5,000 to less than 4,000 radiocarbon years B.P. and indicates a desert shrub to grassland transition. This finding indicates that the dry altithermal of the Bryan-Antevs model may have been a reality in southern New Mexico. The 2nd deposit dated at younger than 2300 radiocarbon years indicates a drying trend that probably was not extreme. The 3rd deposit studied is younger than 1100 radiocarbon years and seems to indicate conditions very similar to those at the time end of the oldest cycle of deposition and grassland conditions.}, keywords = {article, articles, fossil pollen, geomorphology,alluvial deposits,pollen, Holocene,pollen, journal, journals, pollen, Holocene alluvial deposits, pollen, radiocarbon dating, radiocarbon dating,pollen, soil,alluvial deposits}, author = {Freeman, C. E.} } @article {52633, title = {Saving livestock from starvation on Southwestern ranges}, year = {1924}, month = {1924}, pages = {22 }, publisher = {U.S. Department of Agriculture, Farmers{\textquoteright} Bulletin 1428}, keywords = {government publication, livestock, Southwestern ranges, starvation}, author = {Forsling, C.L.} } @article {52640, title = {Chopped soapweed as emergency feed for cattle on Southwestern ranges}, year = {1919}, month = {January 29, 1919}, pages = {20 }, abstract = {Heavy losses of stock resulting from long periods of drought are the greatest handicap of the stock industry on Southwestern ranges. Such droughts have occurred at intervals of 3 to 10 years. When these droughts continue for more than a year, the situation becomes critical due to the lack of range forage or other available feed. Cottonseed products serve well as supplemental feed in times when enough range forage is available to provide the necessary roughage. During prolonged droughts like the present one, which began early in 1916 and continues unbroken to the present (June 15, 1918), the range forage crop may be so small as to require other roughage, as well as concentrated feeds. The problem may be solved in part in some of the less arid regions by raising fodder crops using dry farming. The ranges where this is practical at present, however, are not extensive. On a few ranges adjacent to irrigated districts, the necessary emergency feeds might be furnished by crops from those irrigated areas. But this supply, at best, would be restricted to ranges in the immediate vicinity of the irrigated areas and would not provide emergency feed for the larger portions of the Southwestern ranges where losses have been heavy and breeding herds established through years of effort have been sacrified. In hopes of meeting the problem on such ranges, at least to an extent which will make it possible to maintain the breeding herd over critical periods, the Department of Agriculture has been cooperating for a number of years with a practical stockman on the Jornada Range Reserve in southern New Mexico in working out a comprehensive plan of range management and supplemental feeding. For several years, this plan has included investigating the use of native vegetation as emergency feed. The results of range management with supplemental feeding and initial tests to determine the value of soapweed as ensilage were reported in Department of Agriculture Bulletin 588. Later investigations, including extensive experimental feeding, have shown conclusively that soapweed, if properly utilized, has great value as an emergency stock feed.}, keywords = {cattle, emergency, feed, government publication, soapweed, Southwestern ranges}, url = {/files/bibliography/007.pdf}, author = {Forsling, C.L.} } @article {JRN54199, title = {Range Cow Maintenance on Yucca and Sotol}, volume = {114}, year = {1918}, publisher = {New Mexico College of Agriculture and Mechanic Arts}, abstract = {

Owing to the overstocking of the ranges and the not infrequent drouths of the Southwest, stockmen in this region have for years been seeking some native plants, inured ot the climate not ordinarily considered a stock food that would help out these conditions.\  The experiments in this direction have already shown the value of some varieties of the cactus for this prupose.\  The investigations of the Station, conductied by Professor R.F. Hare\  a number of years ago, both at this institution and at San Antonio, Texas, in co-operation with the United States Department of Agriculture, showed the composition, digestibility and food value of the cactus, and developed new methods of handling and feeding it.\  The results of this investigation are published in Bulletin No. 60. "Prickly Pear and Other Cacti as Food for stock," by D. Griffiths and R.F. Hare.

}, keywords = {cactus, sotol, Turney, Yucca}, url = {/files/bibliography/1918-1.pdf}, author = {Foster, Luther and Humble, Cleveland W.} }