@article {JRN55414, title = {Cross-Site comparisons of dryland ecosystem response to climate change in the US Long-Term Ecological Research Network}, journal = {BioScience}, volume = {72}, year = {2022}, month = {8/16/2022}, pages = {889-907}, abstract = {Long-term observations and experiments in diverse drylands reveal how ecosystems and services are responding to climate change. To develop generalities about climate change impacts at dryland sites, we compared broadscale patterns in climate and synthesized primary production responses among the eight terrestrial, nonforested sites of the United States Long-Term Ecological Research (US LTER) Network located in temperate (Southwest and Midwest) and polar (Arctic and Antarctic) regions. All sites experienced warming in recent decades, whereas drought varied regionally with multidecadal phases. Multiple years of wet or dry conditions had larger effects than single years on primary production. Droughts, floods, and wildfires altered resource availability and restructured plant communities, with greater impacts on primary production than warming alone. During severe regional droughts, air pollution from wildfire and dust events peaked. Studies at US LTER drylands over more than 40 years demonstrate reciprocal links and feedbacks among dryland ecosystems, climate-driven disturbance events, and climate change.}, keywords = {ANPP, climate change, disturbance, drought, LTER, wildfire}, doi = {https://doi.org/10.1093/biosci/biab134}, url = {files/bibliography/22-023.pdf}, author = {Amy R Hudson and Debra P C Peters and John M Blair and Daniel L. Childers and Peter T Doran and Kerrie Geil and Micheal Gooseff and Katherine L Gross and Nick Haddad and Melissa A Pastore and Jennifer A Rudgers and Osvaldo Sala and Eric W Seabloom and Gaius Shaver} } @article {JRN55280, title = {A Comparison of Approaches to Regional Land-Use Capability Analysis for Agricultural Land-Planning}, journal = {Land}, volume = {10}, year = {2021}, month = {04/2021}, chapter = {458}, abstract = {: Smallholder agriculture is a major source of income and food for developing nations. With more frequent drought and increasing scarcity of arable land, more accurate land-use planning tools are needed to allocate land resources to support regional agricultural activity. To address this need, we created Land Capability Classification (LCC) system maps using data from two digital soil maps, which were compared with measurements from 1305 field sites in the Dosso region of Niger. Based on these, we developed 250 m gridded maps of LCC values across the region. Across the region, land is severely limited for agricultural use because of low available water-holding capacity (AWC) that limits dry season agricultural potential, especially without irrigation, and requires more frequent irrigation where supplemental water is available. If the AWC limitation is removed in the LCC algorithm (i.e., simulating the use of sufficient irrigation or a much higher and more evenly distributed rainfall), the dominant limitations become less severe and more spatially varied. Finally, we used additional soil fertility data from the field samples to illustrate the value of collecting contemporary data for dynamic soil properties that are critical for crop production, including soil organic carbon, phosphorus and nitrogen.}, keywords = {agricultural, drought, land capability classifications, land degradation, vulnerability}, doi = {https://doi.org/10.3390/land10050458}, url = {files/bibliography/21-014.pdf}, author = {Ippolito, Tara A. and Jeffrey E. Herrick and Dosswa, Eckwe and Garba, Maman and Ouattara, Mamadou and Singh, Upendra and Stewart, Zachary and Prasad, P. V. Vara and Oumarou, Idrissa A. and J. Neff} } @article {JRN55318, title = {Ecological theory and practice in arid and semiarid ecosystems: a tale of two LTER sites}, volume = {59}, year = {2021}, pages = {151-180}, publisher = {Archimedes (New Studies in the History and Philosophy of Science and Technology)}, abstract = {The chapter compares the conceptual history of two Long Term Ecological Research (LTER) programs at U.S. Department of Agriculture (USDA) research sites established following land overuse in the early 1900s. Early USDA studies were based on a Clementsian model, where vegetation following disturbance was expected to return to the climax determined by climate and soils. Management-based alternatives to the Clementsian model were developed after the dominant vegetation failed to recover and alternative states were observed. The Central Plains Experimental Range LTER (later Shortgrass Steppe LTER) program began in 1981 at a site in northern Colorado. Early studies focused on the inability of the dominant species, blue grama (Bouteloua gracilis), to recover on long-abandoned agricultural fields. These observations were in contrast to the resilience of blue grama-dominated ecosystems in response to livestock grazing and drought. The Jornada Basin LTER program began in 1982 at a Chihuahuan Desert site in southern New Mexico, where black grama-dominated (Bouteloua eriopoda) grasslands converted to shrublands following livestock overgrazing and drought. Early Jornada studies focused on the causes and consequences of this desertification. In collaboration with USDA scientists, the two LTER programs developed new research ideas and approaches which brought an improved understanding of historic dynamics and nuance to the Clementsian-based paradigm. New paradigms also reflected the importance of objective, long-term studies and the dynamic, multi-scale nature of these arid and semiarid ecosystems. Comparing two LTER programs at research sites sharing a conceptual basis, but with different ecosystem properties, can provide insights into the development of US grassland ecology over the past century.}, keywords = {arid ecosystems, desertification, drought, Ecological climax, grassland ecology, International Biological Program, livestock grazing, long-term ecological research, LTER program}, isbn = {978-3-030-66932-4}, doi = {10.1007/978-3-030-66933-1_6}, author = {Debra C. Peters} } @article {JRN55147, title = {Spatio-temporal variation of crop loss in the United States from 2001 to 2016}, journal = {Environmental Research letters}, volume = {14}, year = {2019}, month = {07/2019}, pages = {1-12}, chapter = {1}, abstract = {

Crop insurance loss data can illuminate variations in agricultural impacts from exposure to weather and climate-driven events, and can improve our understanding of agricultural vulnerabilities. Here we perform a retrospective analysis of weather and climate-driven reasons for crop loss (i.e. cause of loss) obtained from the Risk Management Agency of the United States Department of Agriculture. The federal crop insurance program has insured over $440 billion in liabilities representing farmers{\textquoteright} crops from 2001 to 2016. Specifically, we examine the top ten weather and climate-driven causes of loss from 2001 to 2016 across the nation comprising at least 83\% of total indemnities (i.e. insurance payouts provided to farmers after crop loss events). First, we analyzed the relative fraction of indemnities by causes of loss, over different spatial and temporal resolutions. We found that drought and excess precipitation comprised the largest sources of crop loss across the nation. However, these causes varied strongly over space and time. We applied two additional normalization techniques to indemnities using (1) insurance premia and the gross domestic product implicit price deflator, and (2) liabilities to calculate the loss cost. We conducted trend analyses using the Mann{\textendash}Kendall statistical test on loss cost over time. Differential trends and patterns in loss cost demonstrated the importance of spatio-temporal resolution in assessing causes of loss. The majority of monthly significant trends (p \< 0.05) showed increasing loss cost (i.e. increasing indemnities or decreasing liabilities) in response to weather events. Finally, we briefly discuss an online portal (AgRisk Viewer) to make these data accessible at multiple spatial scales and sub-annual time steps to support both research and outreach efforts promoting adaptation and resilience in agricultural systems.

}, keywords = {adaptation, agriculture, climate change, crop insurance, drought, extreme weather, vulnerability}, doi = {doi.org/10.1088/1748-9326/ab1ac9}, url = {files/bibliography/19-018.pdf}, author = {J.T. Reyes and Emile H. Elias} } @article {JRN54668, title = {Pushing precipitation to the extremes in distributed experiments: recommendations for simulating wet and dry years}, journal = {Global Change Biology}, volume = {23}, year = {2017}, pages = {1774-1782}, abstract = {

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

}, keywords = {climate extremes, drought, field experiments, precipitation regimes, wet years}, doi = {10.1111/gcb.13504}, url = {files/bibliography/JRN00660.pdf}, author = {A. K. Knapp and Avolio, Meghan L. and Claus Beier and Carroll, Charles J. W. and S.L. Collins and Dukes, Jeffrey S. and Fraser, Lauchlan H. and Griffin-Nolan, Robert J. and David L. Hoover and Jentsch, Anke and Loik, Michael E. and Richard P. Phillips and Post, Alison K. and O. E. Sala and Slette, Ingrid J. and Laura Yahdjian and M. D. Smith} } @article {JRN54576, title = {Few multiyear precipitation{\textendash}reduction experiments find a shift in the productivity{\textendash}precipitation relationship}, journal = {Global Change Biology}, volume = {22}, year = {2016}, pages = {2570-2581}, abstract = {

Well-defined productivity{\textendash}precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity{\textendash}precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation{\textendash}reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation{\textendash}manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity{\textendash}precipitation relationship downward the spatial fit. The majority of experiments (72\%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation{\textendash}reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid.

}, keywords = {aboveground productivity, ANPP, drought, precipitaiton, precipitation-reduction experiments, spatial fit, temporal fit}, doi = {10.1111/gcb.13269}, url = {files/bibliography/JRN54576.pdf}, author = {Marc Estiarte and Sara Vicca and Josep Pe{\~n}uelas and Michael Bahn and Claus Beier and Bridget A. Emmett and Philip A. Fay and Paul J . Hanson and Roland Hasibeder and Jaime Kigel and G. Kroel-Dulay and Klaus Steenberg Larsen and Lellei -Kov{\'a}cs, Eszter and Jean-Marc Limousin and Ogaya, Rom{\`a} and Jean-Marc Ourcival and Sabine Reinsch and O. E. Sala and Inger Kappel Schmidt and Marcelo Sternberg and Tielb{\"o}rger, Katja and Albert Tietema and Ivan A. Janssens} } @article {JRN54225, title = {Characterizing differences in precipitation regimes of extreme wet and dry years: implications for climate change experiments}, journal = {Global Change Biology}, volume = {21}, year = {2015}, pages = {2624-2633}, abstract = {

Climate change is intensifying the hydrologic cycle and is expected to increase the frequency of extreme wet and dry years. Beyond precipitation amount, extreme wet and dry years may differ in other ways, such as the number of precipitation events, event size, and the time between events. We assessed 1614 long-term (100 year) precipitation records from around the world to identify key attributes of precipitation regimes, besides amount, that distinguish statistically extreme wet from extreme dry years. In general, in regions where mean annual precipitation (MAP) exceeded 1000 mm, precipitation amounts in extreme wet and dry years differed from average years by ~40\% and 30\%, respectively. The magnitude of these deviations increased to \>60\% for dry years and to \>150\% for wet years in arid regions (MAP\<500 mm). Extreme wet years were primarily distinguished from average and extreme dry years by the presence of multiple extreme (large) daily precipitation events (events \>99th percentile of all events); these occurred twice as often in extreme wet years compared to average years. In contrast, these large precipitation events were rare in extreme dry years. Less important for distinguishing extreme wet from dry years were mean event size and frequency, or the number of dry days between events. However, extreme dry years were distinguished from average years by an increase in the number of dry days between events. These precipitation regime attributes consistently differed between extreme wet and dry years across 12 major terrestrial ecoregions from around the world, from deserts to the tropics. Thus, we recommend that climate change experiments and model simulations incorporate these differences in key precipitation regime attributes, as well as amount into treatments. This will allow experiments to more realistically simulate extreme precipitation years and more accurately assess the ecological consequences.

}, keywords = {climate change experiments, climate extremes, drought, ecoregions, global patterns, precipitation, rainfall patterns}, doi = {10.1111/gcb.12888}, url = {files/bibliography/JRN00634.pdf}, author = {A. K. Knapp and David L. Hoover and Wilcox, Kevin R. and Avolio, Meghan L. and Koerner, Sally E. and La Pierre, Kimberly J. and Loik, Michael E. and Luo, Yiqi and O. E. Sala and M. D. Smith} } @article {JRN54167, title = {Enhanced precipitation variability effects on water losses and ecosystem functioning: differential response of arid and mesic regions}, journal = {Climate Change}, volume = {131}, year = {2015}, month = {07/2015}, pages = {213-227}, chapter = {213}, abstract = {

Climate change will result in increased precipitation variability with more extreme events reflected in more frequent droughts as well as more frequent extremely wet conditions. The increase in precipitation variability will occur at different temporal scales from intra to inter-annual and even longer scales. At the intra-annual scale, extreme precipitation events will be interspersed with prolonged periods in between events. At the inter-annual scale, dry years or multi-year droughts will be combined with wet years or multi-year wet conditions. Consequences of this aspect of climate change for the functioning ecosystems and their ability to provide ecosystem services have been underexplored. We used a process-based ecosystem model to simulate water losses and soil-water availability at 35 grassland locations in the central US under 4 levels of precipitation variability (control, +25, +50+75 \%) and six temporal scales ranging from intra- to multi-annual variability. We show that the scale of temporal variability had a larger effect on soil-water availability than the magnitude of variability, and that inter- and multi-annual variability had much larger effects than intraannual variability. Further, the effect of precipitation variability was modulated by mean annual precipitation. Arid-semiarid locations receiving less than about 380 mm yr-1 mean annual precipitation showed increases in water availability as a result of enhanced precipitation variability while more mesic locations (\>380 mm yr-1) showed a decrease in soil water availability. The beneficial effects of enhanced variability in arid-semiarid regions resulted from a deepening of the soil-water availability profile and a reduction in bare soil evaporation. The deepening of the soil-water availability profile resulting from increase precipitation variability may promote future shifts in species composition and dominance to deeper-rooted woody plants for ecosystems that are susceptible to state changes. The break point, which has a mean of 380-mm with a range between 440 and 350 mm, is remarkably similar to the 370-mm threshold of the inverse texture hypothesis, below which coarse-texture soils had higher productivity than fine-textured soils.

}, keywords = {climate change, drought, model, precipitation variability, rainfall variability, soil-water availability}, doi = {10.1007/s10584-015-1389-z}, url = {/files/bibliography/15-013.pdf}, author = {O. E. Sala and Laureano A. Gherardi and Debra C. Peters} } @article {JRN54224, title = {Responses of a desert nematode community to changes in water availability}, journal = {Ecosystems}, volume = {6}, year = {2015}, chapter = {Article 44}, abstract = {

The most recent climate models unequivocally predict a strong drying trend for the southwestern USA within the next century. Soil nematodes are a highly important component of desert ecosystem functioning, but rely on water films formovement. However, it is currently poorly understood how different trophic groups of nematodes respond to chronic presses as well as short-lived pulses of altered water availability, especially in arid systems where such changes are expected to have the greatest impact. The aim of this study was to assess the effects of both instantaneous and long-term variation in water availability on desert soil nematode trophic groups.We hypothesized that nematode abundance would respond positively to both short- and long-term increases in moisture. Based on the ecology of the different trophic groups we further made predictions about their relative rates of response. We increased or decreased precipitation from ambient levels in the Chihuahuan Desert for four consecutive years and sampled soil nematodes after two, three and four years. We tested the effects of altered precipitation treatments through time as well as gravimetric soil moisture at the time of sampling on the abundance of the different nematode trophic groups. In contrast to our hypotheses, the abundances of most nematode trophic groups were unaffected by the amount of precipitation, even after four years of altered precipitation. Plant-parasitic nematodes from low moisture soils were the only group that reacted positively to increased precipitation from the third year onwards. Trophic groups responded differently to soil moisture, with bacterivores decreasing with increasing moisture and omnivores showing a positive relationship that diminished over time. We show that in general, these desert nematodes were not limited by precipitation, and were highly resilient to decreases therein. However, when also considering the effects of soil moisture, some more complex patterns and differences among trophic groups emerged.We discuss potential mechanisms explaining these observations and contrast our findings with those from other ecosystems around the world. We conclude that deserts harbor nematode communities that seem more resilient to altered water availability than other ecosystems.

}, keywords = {drought, nematodes, precipitation, resilience, soil ecology, soil moisture, trophic groups, water availability}, doi = {10.1890/ES14-00319.1}, url = {files/bibliography/JRN00643.pdf}, author = {Vandegehuchte, Martin L. and Sylvain, Zachary A. and Lara Reichmann and Cecilia M. de Tomasel and Nielsen, Uffe N. and D.H. Wall and O. E. Sala} } @article {JRN54130, title = {Quantifying drylands{\textquoteright} drought resistance and recovery: the importance of drought intensity, dominant life history and grazing regime}, journal = {Global Change Biology}, year = {2014}, pages = {1-16}, abstract = {

Projected global change will increase the level of land-use and environmental stressors such as drought and grazing, particularly in drylands. Still, combined effects of drought and grazing on plant production are poorly understood, thus hampering adequate projections and development of mitigation strategies. We used a large, cross-continental database consisting of 174 long-term datasets from \>30 dryland regions to quantify ecosystem responses to drought and grazing with the ultimate goal to increase functional understanding in these responses. Two key aspects of ecosystem stability, resistance to and recovery after a drought, were evaluated based on standardized and normalized aboveground net primary production (ANPP) data. Drought intensity was quantified using the standardized precipitation index. We tested effects of drought intensity, grazing regime (grazed, ungrazed), biome (grassland, shrubland, savanna) or dominant life history (annual, perennial) of the herbaceous layer to assess the relative importance of these factors for ecosystem stability, and to identify predictable relationships between drought intensity and ecosystem resistance and recovery. We found that both components of ecosystem stability were better explained by dominant herbaceous life history than by biome. Increasing drought intensity (quasi-) linearly reduced ecosystem resistance. Even though annual and perennial systems showed the same response rate to increasing drought intensity, they differed in their general magnitude of resistance, with annual systems being ca. 27\% less resistant. In contrast, systems with an herbaceous layer dominated by annuals had substantially higher postdrought recovery, particularly when grazed. Combined effects of drought and grazing were not merely additive but modulated by dominant life history of the herbaceous layer. To the best of our knowledge, our study established the first predictive, cross-continental model between drought intensity and drought-related relative losses in ANPP, and suggests that systems with an herbaceous layer dominated by annuals are more prone to ecosystem degradation under future global change regimes.

}, keywords = {ANPP, climate change, cross-continental, cross-site, drought, drylands, model, recovery, resilience, resistance, stability}, doi = {10.1111/gcb.12777}, author = {Ruppert, Jan C. and Harmoney, Keith and Henkin, Zalmen and Snyman, Hennie A. and Marcelo Sternberg and Walter Willms and Linstadter, Anja} } @article {JRN54396, title = {Soil animal responses to moisture availability are largely scale, not ecosystem dependent: Insight from a cross-site study}, journal = {Global Change Biology}, volume = {20}, year = {2014}, month = {02/2014}, pages = {2631-2643}, chapter = {2631}, abstract = {

Climate change will result in reduced soil water availability in much of the world either due to changes in precipitation or increased temperature and evapotranspiration. Responses of communities of mites and nematodes to changes in moisture availability are not well known, yet these organisms play important roles in decomposition and nutrient cycling processes. We determined how communities of these organisms respond to changes in moisture availability and whether common patterns occur along fine-scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert) located in the western United States and Antarctica, as well as across a cross-ecosystem moisture gradient (CEMG) of all four ecosystems considered together. An elevation transect of three sampling plots was monitored within each ecosystem and soil samples were collected from these plots and from existing experimental precipitation manipulations within each ecosystem once in fall of 2009 and three times each in 2010 and 2011. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. Changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems may result in shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition and soil properties may influence this relationship over larger scales.

}, keywords = {climate change, desert, drought, grassland, mites, nematodes}, doi = {10.1111/gcb.12522}, url = {/files/bibliography/14-037.pdf}, author = {Sylvain, Zachary A. and D.H. Wall and Karie Cherwin and Lara Reichmann and Debra C. Peters and O. E. Sala} } @article {49860, title = {Ecosystem resilience despite large-scale altered hydroclimatic conditions}, journal = {Nature}, volume = {494}, year = {2013}, month = {2013}, pages = {349-352}, chapter = {349}, abstract = {

Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological model for many regions1. Largescale, warm droughts have recently occurred in North America, Africa, Europe, Amazonia and Australia, resulting in major effects on terrestrial ecosystems, carbon balance and food security2,3. Here we compare the functional response of above-ground net primary production to contrasting hydroclimatic periods in the late twentieth century (1975{\textendash}1998), and drier, warmer conditions in the early twenty-first century (2000{\textendash}2009) in the Northern and Southern Hemispheres. We find a common ecosystem water-use efficiency (WUEe: above-ground net primary production/evapotranspiration) across biomes ranging from grassland to forest that indicates an intrinsic system sensitivity to water availability across rainfall regimes, regardless of hydroclimatic conditions. We found higher WUEe in drier years that increased significantly with drought to a maximum WUEe across all biomes; and a minimum native state in wetter years that was common across hydroclimatic periods. This indicates biome-scale resilience to the interannual variability associated with the early twenty-first century drought{\textemdash}that is, the capacity to tolerate low, annual precipitation and to respond to subsequent periods of favourable water balance. These findings provide a conceptual model of ecosystem properties at the decadal scale applicable to the widespread altered hydroclimatic conditions that are predicted for later this century. Understanding the hydroclimatic threshold that will break down ecosystem resilience and alter maximum WUEe may allow us to predict land-surface consequences as large regions become more arid, starting with waterlimited, low-productivity grasslands.

}, keywords = {aboveground net primary production, air temperature, ANPP, climate change, drought, ecosystem resilience, evapotranspiration, hydroclimate, MODIS, plant production, precipitation}, doi = {10.1038/nature11836}, url = {/files/bibliography/13-022.pdf}, author = {Guillermo E. Ponce-Campos and S. Moran and Alfredo Huete and Yongguang Zhang and Bresloff, Cynthia and T. Huxman and Eamus, Derek and David D. Bosch and Anthony R. Buda and Stacey A. Gunter and Scalley, Tamara Heartsill and S.G. Kitchen and M.P. McClaran and McNab, W. Henry and Montoya, Diane S. and Jack A. Morgan and Debra C. Peters and John Sadler and M. S. Seyfried and Paul F. Starrs} } @article {49909, title = {Response of dominant grass and shrub species to water manipulation: An ecophysiological basis for shrub invasion in a Chihuahuan Desert grassland}, journal = {Oecologia}, volume = {169}, year = {2012}, month = {01/15/2012}, pages = {373-383}, chapter = {373}, abstract = {Increases in woody vegetation and declines in grasses in arid and semi-arid ecosystems have occurred globally since the 1800s, but the mechanisms driving this major land-cover change remain uncertain and controversial. Working in a shrub-encroached grassland in the northern Chihuahuan Desert where grasses and shrubs typically differ in leaf-level nitrogen allocation, photosynthetic pathway, and root distribution, we asked if differences in leaflevel ecophysiology could help explain shrub proliferation. We predicted that the relative performance of grasses and shrubs would vary with soil moisture due to the diVerent morphological and physiological characteristics of the two life-forms. In a 2-year experiment with ambient, reduced, and enhanced precipitation during the monsoon season, respectively, the encroaching C3 shrub (honey mesquite Prosopis glandulosa) consistently and substantially outperformed the historically dominant C4 grass (black grama Bouteloua eriopoda) in terms of photosynthetic rates while also maintaining a more favorable leaf water status. These differences persisted across a wide range of soil moisture conditions, across which mesquite photosynthesis was decoupled from leaf water status and moisture in the upper 50 cm of the soil proWle. Mesquite\’s ability to maintain physiologically active leaves for a greater fraction of the growing season than black grama potentially ampliWes and extends the importance of physiological differences. These physiological and phenological differences may help account for grass displacement by shrubs in drylands. Furthermore, the greater sensitivity of the grass to low soil moisture suggests that grasslands may be increasingly susceptible to shrub encroachment in the face of the predicted increases in drought intensity and frequency in the desert of the southwestern USA.}, keywords = {drought, grassland community, Jornada, photosynthesis, precipitation manipulation, shrub invasion, water manipulation, water potential, woody encroachment}, doi = {10.1007/s00442-011-2217-4}, url = {/files/bibliography/12-015.pdf}, author = {Heather L. Throop and Lara Reichmann and O. E. Sala and Steven R. Archer} } @article {49913, title = {Effects of seasonal grazing, drought, fire, and carbon enrichment on soil icroarthropods in a desert grassland}, journal = {Journal of Arid Environments}, volume = {83}, year = {2012}, month = {06/01/2012}, pages = {10-14}, chapter = {10}, abstract = {

This study was designed to test hypotheses about the combined effects of short-term, seasonal grazing with seasonal drought, fire, and carbon enrichment on soil microarthropod communities in a Chihuahuan Desert grassland. The study was conducted in eighteen 0.5 ha plots following three consecutive years of treatment: six plots intensively grazed in summer, six in winter, and six not grazed. There was no difference in perennial grass cover on the summer-grazed and winter-grazed plots. Intensive seasonal grazing had no effect on the abundance and community composition of soil microarthropods. Within each plot there were six subplots: summer rain-out, winter rain-out, burned, glucose amendment, rainout control and burn-glucose control. Fire and carbon enrichment had no significant effect on soil microarthropod abundance or community composition. The average number of microarthropods ranged from 8915 {\textpm} 1422 m-2 in the ungrazed, unburned plots to 7175 {\textpm} 1232 m-2 in the winter-grazed, unburned plots. Microarthropod densities in the glucose-amended plots were 8917 {\textpm} 4902 m-2 in the winter-grazed plots and 10,731 {\textpm} 863 m-2 in the glucose-amended, summer-grazed subplots. The prostigamatid mite, Tydeus sp., was the most abundant microarthropod taxon in all treatment plots. {\textcopyright} 2012 Elsevier Ltd. All rights reserved

}, keywords = {carbon enrichment, cattle, drought, fire, perennial grass cover, prostigmatid mite, rain-out shelter, soil microarthropods}, doi = {10.1016/j.jaridenv.2012.03.021}, url = {/files/bibliography/12-017.pdf}, author = {Walter G. Whitford and Yosef Steinberger} } @article {49982, title = {Cross-system comparisons elucidate disturbance complexities and generalities}, journal = {Ecosphere}, volume = {2}, year = {2011}, month = {07/2011}, pages = {Article 81}, chapter = {1}, abstract = {Given that ecological effects of disturbance have been extensively studied in many ecosystems, it is surprising that few quantitative syntheses across diverse ecosystems have been conducted. Multi-system studies tend to be qualitative because they focus on disturbance types that are difficult to measure in an ecologically relevant way. In addition, synthesis of existing studies across systems or disturbance types is challenging because sufficient information needed for analysis is not easily available. Theoretical advances and improved predictions can be advanced by generalizations obtained from synthesis activities that include multiple sites, ecosystems, and disturbance events. Building on existing research, we present a conceptual framework and an operational analog to integrate this rich body of knowledge and to promote quantitative comparisons of disturbance effects across different types of ecosystems and disturbances. This framework recognizes individual disturbance events that consist of three quantifiable components: (1) environmental drivers, (2) initial system properties, and (3) physical and biological mechanisms of effect, such as deposition, compaction, and combustion. These components result in biotic and abiotic legacies that can interact with subsequent drivers and successional processes to influence system response. Through time, a coarse-scale quasi-equilibrial state can be reached where variation in drivers interacting with biotic processes and feedbacks internal to the system results in variability in dynamics. At any time, a driver of sufficient magnitude can push the system beyond its realm of natural variability to initiate a new kind of event. We use long-term data from diverse terrestrial ecosystems to illustrate how our approach can facilitate cross-system comparisons, and provide new insights to the role of disturbance in ecological systems. We also provide key disturbance characteristics and measurements needed to promote future quantitative comparisons across ecosystems.}, keywords = {disburbance event, disturbance type, drought, ecological theory, global change, hurricane legacies, overgrazing, thresholds, wildfire}, doi = {10.1890/es11-00115.1}, url = {/files/bibliography/11-015.pdf}, author = {Debra C. Peters and Ariel E. Lugo and F.S. Chapin III and Steward T.A. Pickett and Danielle Duni and Rocha, Adrian V. and F. J. Swanson and C. Laney and J. W. Jones (eds.)} } @article {50139, title = {Historical and modern distrubance regimes, strand structures, and landscape dynamics in pinon-juniper vegetation of the western United States}, journal = {Rangeland Ecology and Management}, volume = {62}, year = {2009}, month = {03/2009}, pages = {203-222}, chapter = {203}, abstract = {

Pi{\~n}on{\textendash}juniper is a major vegetation type in western North America. Effective management of these ecosystems has been hindered by inadequate understanding of 1) the variability in ecosystem structure and ecological processes that exists among the diverse combinations of pi{\~n}ons, junipers, and associated shrubs, herbs, and soil organisms; 2) the prehistoric and historic disturbance regimes; and 3) the mechanisms driving changes in vegetation structure and composition during the past 150 yr. This article summarizes what we know (and don{\textquoteright}t know) about three fundamentally different kinds of pi{\~n}on{\textendash}juniper vegetation. Persistent woodlands are found where local soils, climate, and disturbance regimes are favorable for pi{\~n}on, juniper, or a mix of both; fires have always been infrequent in these woodlands. Pi{\~n}on{\textendash}juniper savannas are found where local soils and climate are suitable for both trees and grasses; it is logical that low-severity fires may have maintained low tree densities before disruption of fire regimes following Euro-American settlement, but information is insufficient to support any confident statements about historical disturbance regimes in these savannas. Wooded shrublands are found where local soils and climate support a shrub community, but trees can increase during moist climatic conditions and periods without disturbance and decrease during droughts and following disturbance. Dramatic increases in tree density have occurred in portions of all three types of pi{\~n}on{\textendash}juniper vegetation, although equally dramatic mortality events have also occurred in some areas. The potential mechanisms driving increases in tree density{\textemdash}such as recovery from past disturbance, natural range expansion, livestock grazing, fire exclusion, climatic variability, and CO2 fertilization{\textemdash}generally have not received enough empirical or experimental investigation to predict which is most important in any given location. The intent of this synthesis is 1) to provide a source of information for managers and policy makers; and 2) to stimulate researchers to address the most important unanswered questions.La vegetaci{\'o}n de Pi{\~n}on-jun{\'\i}pero es un tipo de vegetaci{\'o}n muy importante en el Oeste de Norte Am{\'e}rica. El manejo efectivo de estos ecosistemas se ha obstaculizado por el inadecuado entendimiento de 1) la variabilidad en la estructura del ecosistema y los procesos ecol{\'o}gicos que existen entre las diversas combinaciones de pinos, jun{\'\i}peros, arbustos, hierbas, y los organismos asociados del suelo; 2) reg{\'\i}menes prehist{\'o}ricos e hist{\'o}ricos del disturbio, y 3) mecanismos que conducen cambios en estructura y composici{\'o}n de la vegetaci{\'o}n durante los {\'u}ltimos 150 a{\~n}os. Este publicaci{\'o}n hace un resumen de lo que sabemos (y no sabemos) acerca de tres clases fundamentales de vegetaci{\'o}n del pi{\~n}on{\textendash}junipero. Arbolados persistentes se encuentran donde los suelos locales, el clima, y los reg{\'\i}menes del disturbio son favorables para el pi{\~n}{\'o}n, el jun{\'\i}pero, o una mezcla de ambos; los fuegos han sido siempre infrecuentes en estas {\'a}reas. Las sabanas del Pi{\~n}on{\textendash}junipero se encuentran donde los suelos locales y el clima son apropiados tanto para {\'a}rboles y gram{\'\i}neas; es l{\'o}gico que los fuegos de baja-intensidad pueden haber mantenido densidades bajas de {\'a}rboles antes de que se interrumpi{\'o} los reg{\'\i}menes del fuego despu{\'e}s del establecimiento Euro-Americano, pero existe poca informaci{\'o}n para apoyar cualquier afirmaci{\'o}n afirmativa sobre los reg{\'\i}menes hist{\'o}ricos del disturbio en estas sabanas. Los matorrales se localizan donde los suelos locales y el clima apoyan a comunidad de arbustos, pero los {\'a}rboles pueden aumentar durante condiciones clim{\'a}ticas y per{\'\i}odos h{\'u}medos sin disturbio, y disminuyen durante sequ{\'\i}as y despu{\'e}s del disturbio. Los aumentos dram{\'a}ticos en la densidad de los {\'a}rboles han ocurrido en las porciones de los tres tipos de vegetaci{\'o}n del pi{\~n}on{\textendash}junipero, aunque eventos igualmente dram{\'a}ticos de mortalidad han ocurrido tambi{\'e}n en algunas {\'a}reas. Los mecanismos potenciales que conducen aumentos en densidad de {\'a}rboles, la recuperaci{\'o}n del {\'u}ltimo disturbio, la extensi{\'o}n natural del pastizal, el pastoreo del ganado, la exclusi{\'o}n del fuego, la variabilidad clim{\'a}tica, y la fertilizaci{\'o}n-general del CO2 no han recibido suficiente investigaci{\'o}n emp{\'\i}rica o experimental para predecir cu{\'a}l de estos factores puede ser el m{\'a}s importante en cualquiera de los sitios. El intento de esta s{\'\i}ntesis es 1) proporcionar una fuente de informaci{\'o}n para los manejadores y los regidores, y 2) estimular a investigadores para dirigir las preguntas m{\'a}s importantes que aun est{\'a}n sin contestar.

}, keywords = {climate, CO2, drought, fire, grazing, range expansion, tree infill, tree invasion}, url = {/files/bibliography/09-014.pdf}, author = {W.H. Romme and C.D. Allen and J.D. Bailey and W.L. Baker and Brandon T Bestelmeyer and P.M. Brown and K.S. Eisenhart and Floyd-Hanna, L. and D.W. Huffman and Jacobs, B. F. and Richard F. Miller and E. Muldavin and Swetnam, T.W. and R. J. Tausch and Weidberg, P.J.} } @article {50523, title = {Multi-scale factors and long-term responses of Chihuahuan Desert grasses to drought}, journal = {Landscape Ecology}, volume = {21}, number = {8}, year = {2006}, note = {//USDA//LTER IV//entered 7/12/2006; updated 10/16/2006}, month = {2006}, pages = {1217-1231}, chapter = {1217}, abstract = {

Factors with variation at broad (e.g., climate) and fine scales (e.g., soil texture) that influence local processes at the plant scale (e.g., competition) have often been used to infer controls on spatial patterns and temporal trends in vegetation. However, these factors can be insufficient to explain spatial and temporal variation in grass cover for arid and semiarid grasslands during an extreme drought that promotes woody plant encroachment. Transport of materials among patches may also be important to this variation. We used long-term cover data (1915\–2001) combined with recently collected field data and spatial databases from a site in the northern Chihuahuan Desert to assess temporal trends in cover and the relative importance of factors at three scales (plant, patch, landscape unit) in explaining spatial variation in grass cover. We examined cover of five important grass species from two topographic positions before, during, and after the extreme drought of the 1950s. Our results show that dynamics before, during, and after the drought varied by species rather than by topographic position. Different factors were related to cover of each species in each time period. Factors at the landscape unit scale (rainfall, stocking rate) were related to grass cover in the pre- and post-drought periods whereas only the plant-scale factor of soil texture was significantly related to cover of two upland species during the drought. Patch-scale factors associated with the redistribution of water (microtopography) were important for different species in the pre- and post-drought period. Another patch-scale factor, distance from historic shrub populations, was important to the persistence of the dominant grass in uplands (Bouteloua eriopoda) through time. Our results suggest the importance of local processes during the drought, and transport processes before and after the drought with different relationships for different species. Disentangling the relative importance of factors at different spatial scales to spatial patterns and long-term trends in grass cover can provide new insights into the key processes driving these historic patterns, and can be used to improve forecasts of vegetation change in arid and semiarid areas.

}, keywords = {arid grasslands, desertification, drought, grazing, perennial grasses, transport processes}, doi = {10.1007/s10980-006-0025-8}, url = {/files/bibliography/06-034.pdf}, author = {Jin Yao and Debra C. Peters and Kris Havstad and Gibbens, Robert P. and Jeffrey E. Herrick} } @article {50629, title = {Fungal endophytes intrinsically associated with micropropagated plants regenerated from native Bouteloua eriopoda Torr. and Atriplex canescens (Pursh) Nutt.}, journal = {In Vitro Cellular and Developmental Biology-Plant}, volume = {40}, number = {6}, year = {2004}, month = {November 1, 2004}, pages = {608-612}, abstract = {Black grama (Bouteloua eriopoda) and fourwing saltbush (Atriplex canescens) are important grass and shrub species in arid rangelands of the northern Chihuahuan Desert. They are naturally colonized by dark septate endophytic fungi that cannot be eliminated by seed disinfestation. Plants were regenerated from both species and appeared to be fungus free in axenic cultures. Analysis of callus and regenerated plants of both species using dual staining with light and scanning electron microscopy revealed fungal endophytes intrinsically associated with cells, roots and leaves of regenerated plants that are also associated with native plants. Fungal layers and biofilms prevent direct exposure of callus, root or leaf tissues to the external environment. Micropropagation is a valuable tool for identifying key fungal endophytes that enhance drought tolerance in native desert plants.}, keywords = {arid, biofilms, drought, mycorrhizae, symbiosis}, url = {/files/bibliography/04-008.pdf}, author = {J.R. Barrow and P. Osuna-Avila and I. Reyes-Vera} } @proceedings {51395, title = {Reflections from nearly a century of rangeland research in the Jornada Basin}, year = {1995}, month = {May 23-25, 1995}, pages = {2}, abstract = {The 80-year record of rangeland research at the Jornada Experimental Range (JER) is representative of the history of the rangeland science discipline. The initial impetus from research was the rapid and obvious degradation of rangeland resources from misuse and drought from the late 1800{\textquoteright}s to the early part of the twentieth century. Original researchers designed pasture-scale studies to develop guidelines for seasonal stocking rates and methodologies for distributing grazing use. By the 1940{\textquoteright}s, observations on vegetation dynamics, particularly the encroachment of woody species, drove development of research efforts in range improvement techniques. By the 1970{\textquoteright}s, with rangeland management compromised by an increasingly regulated environment and a broadening of resource interests, the appropriateness of research on grazing management and forage improvement technologies was diminished. For the past 20 years rangeland research has been redirected to include more fundamental ecological investigations. The utility of the research had been questioned by various clientele. It is important that we translate this knowledge into usable technologies for monitoring existing conditions, remediation of degraded conditions,and adapting to new management conditions.}, keywords = {drought, Jornada Basin, misuse, rangeland research}, author = {Kris Havstad} } @proceedings {51896, title = {CO2 exchange of the above-ground and below-ground components of Kleingrass (Panicum coloratum L.) during drought in the northern Chihuahuan Desert}, year = {1985}, month = {1985}, pages = {336-338}, address = {Kyoto, Japan}, abstract = {

The effect a 52 day drought had on the die! whole-plant carbon balance of kleingrass (Panicum coloratum L.) growing in the northern Chihuahuan desert was determined. Whole-plant C02 inputs (photosynthesis) and outputs (belowground and aboveground respiration) were measured on day 52 of the drought (June 23, 1981) and 2 days following 1.12 cm of precipitation that occurred on June 24, 1981.

}, keywords = {carbon balance, desert, drought, photosynthesis, root respiration}, url = {/files/bibliography/282.pdf}, author = {Sisson, W.B.} } @proceedings {52184, title = {Brush control and seeding rangeland}, year = {1977}, note = {Paper also presented at Alamogordo and Capitan, NM}, month = {1977}, pages = {43-52}, abstract = {For many people, the romance of the Southwest is the favorable climate--winters are warm and dry and summers are relatively dry so the heat is rarely oppressive. For the range manager, the key word in these descriptions is "dry." Over the arid Southwest, the average annual precipitation is 8 to 12 inches. Averages, however, mean very little. Precipitation varies widely from one time to another and from one place to another, only a few miles away. Rainfall from April through September governs the growing season for range forage. West of the Sacramento Mountains about 55 percent of the average annual precipitation falls from July through September; springs are usually dry and windy. East of the Sacramento Mountains growing-season precipitation is more evenly distributed between spring and summer. The average annual evaporation from Weather Bureau pans is about 90 inches--about 10 times as much as the precipitation. The range plants, therefore, grow in brief bursts when soil moisture is available immediately after rainfall. Droughts are frequent and expected. Infrequent wet spells may bring a false sense of security, but chances are that drought, hopefully short but possibly of several years{\textquoteright} duration, will follow. Stands of perennial grasses are often severely reduced by drought. On the Jornada Experimental Range near Las Cruces, the basal cover of black grama was reduced to 42 percent of its predrought cover during the 1916-18 drought, 11 percent during the 1921-26 drought, and 23 percent in 1934. During the Great Drought from 1951 to 1956, black grama cover was reduced to 1 to 50 percent of its predrought average, depending on soil type. The drought loss was much more severe on deep sandy sites than on sites with shallower sands. Where 99 percent of the black grama was lost there has been no recovery. Droughts are a fact of life in this region and must be anticipated in the management of any southwestern range. There is no evidence that the climate is getting drier.}, keywords = {average annual evaporation, average annual precipitation, brush control, drought, research notes, seeding, Southwest}, url = {/files/bibliography/159.pdf}, author = {C.H. Herbel} } @proceedings {52406, title = {Simulation and Analysis of Dynamics of a Semi-Desert Grassland}, year = {1970}, note = {//USDA//NONE//}, month = {June 19691970}, publisher = {Colorado State University}, address = {University of New Mexico}, abstract = {A problem area in southern New Mexico was selected where data were available on long-term changes in the system, especially the vegetation, as a response to naturally occurring climatic fluctuations. The objective here was to try to extract from experience, the literature, and the data base enough information about the system to represent it in simulation models. Analysis of this total-system problem required crossing disciplines to secure personnel with adequate subject matter and analytical capabilities, operational approaches, and flexibility in attitude, outlook, and operation.}, keywords = {abstract, abstracts, cattle, vegetation interaction, cattle, wildlife relationships, conference, conference proceedings, conferences, drought, ecology, germination, grassland, dynamics, grazing, management, model, ecosystem, model, mathematical, plant, germination, plant, precipitation, precipitation, proceeding, proceedings, rodent, food habits, rodent, life history, rodent, population dynamics, rodent,habitat requirements, rodent,population dynamics, vegetation change}, author = {R. G. Wright and G.M. Van Dyne} } @conference {52434, title = {Drought effects on a southern New Mexico range and the nature of recovery}, booktitle = {21st Annual Meeting, Society for Range Management}, year = {1968}, month = {1968}, pages = {56-57}, keywords = {drought, effects, recovery, southern New Mexico}, author = {C.H. Herbel} } @article {52509, title = {Cry alarm . . . killer loose . . . }, journal = {New Mexico Stockman}, volume = {29}, number = {4}, year = {1961}, month = {1961}, pages = {26-27}, abstract = {Attractive as it appears, cattle ranching may sometimes be likened to gambling against a stacked deck. Uncertain markets plague the budget; the inevitable and dreaded drought, ever lurking around the corner, brings setbacks, death losses, extra feed, labor costs, and many other extraordinary burdens. On the other hand, when welcome rain does finally come and the hills and valleys take on that beautiful green color, elation is tempered by knowing that "tares must grow with the wheat," specifically, poisonousweeds. At any time, the lovely green expanse is likely to be seen flecked with the bloated bodies of dead cattle. This is a sight calculated to take the joy out of life. An ironical twist of this play from the stacked deck lies in the calamity stemming from a totally unexpected source. It can and oftendoes happen; an analogy is the death-dealing plague of 1918. A virulent form of a disease thought to be relatively harmless, the terrible "flu" epidemic swept the world, claiming more victims than the world war just preceding. So too in the plant kingdom a variety of subjects, usually weeds ordinarily harmless, grazed and relished by livestock as good forage, will suddenly turn traitor. Chemical changes occurring under climatic or other conditions affecting plant growth can transform these weeds overnight into deadly killers. Another deal from the stacked deck--the plant known to be toxic but by its infrequent and scattered occurrence presents no immediate threat. Comes a severe drought or some other disturbing factor and the inhibitor is removed. The erstwhile harmless plant then burgeons into dense colonies, its very abundance enhancing the hazard a thousandfold. It is then taken in lethal quantities by cattle; result, severe losses by a "new" killer plant.}, keywords = {cattle ranching, chemical changes, disease, drought, poisonous weeds}, url = {/files/bibliography/083.pdf}, author = {F.N. Ares} } @article {52589, title = {Ways and means to minimize the ill effects of drought on black grama ranges}, number = {Research Note 82}, year = {1939}, month = {1939}, pages = {7}, institution = {USDA, Forest Service, Southwest Forest and Range Experimental Range Station}, abstract = {Black grama ranges of southern New Mexico and adjacent portions of Arizona and Texas have the largely unmerited reputation of being excessively vulnerable to drought. Actually, a complete failure of the forage crop is as rare here as is the complete failure of crops in regions of higher rainfall. Climatic data support this statement and provide the best index to the frequency of lean years. Long-time precipitation records taken at the Jornada Experimental Range and supporting experience indicate that each 10-year period may be expected to include 1 year of drought and 2 or more critically dry years. During these dry years the forage growth is far below that of the average year. Forage estimates and grazing capacity figures indicate that the feed supply will vary 60 percent or more between good and poor years. With complete annual use, the current forage crop cannot always be depended on year in and year out to support an unvarying number of cattle. Clearly, if sustained grazing capacity is to be maintained, the feed produced in drought years must be supplemented in some manner.}, keywords = {black grama, drought, effects, research notes}, url = {/files/bibliography/051.pdf}, author = {Canfield, R.H.} } @article {52608, title = {After the drought}, journal = {The American Cattle Producer}, volume = {17}, number = {1}, year = {1935}, month = {1935}, pages = {3-5}, abstract = {In the Southwest, rainfall has been deficient ever since 1930; and, as a climax, 1934 was as dray as a lost caravan in the Gobi Desert. In southern New Mexico, the average annual rainfall is about 9 inches; but, in 1934, Jupiter Pluvius failed to function in customary fashion and furnished only a little over half the usual amount. For the first 9 months of 1934, rainfall in several southern New Mexico counties was less than 40 percent of the average, so that forage production on both summer and winter ranges was far below normal. This drought, one of the worst in Southwestern annals, caused severe cattle losses, complicated range management and necessitated emergency supplemental feeding, sacrifice sales, and forced shipments of cattle from the impoverished open range country. Government records show 1934 to be excelled only by the notable drought of 1903-04. What can be done to prevent the regular repetition of the tragedy of drought? Artificial rainmaking has invariably failed. Are there any practical methods of circumventing dry weather and its range-depleting effects? How can Southwestern cattlemen fortify their ranges against ultimate deterioration by both drought and overgrazing? What can be done to increase the stability and improve the economy of cattle grazing in the far-flung Southwest? Suggestions that may be helpful in planning for the future can be obtained by a careful screening of the results from the Jornada Experimental Range located near Las Cruces, New Mexico. Here the U.S. Forest Service has, among other things, studied the minimization of drought losses, the upbuilding of depleted ranges, the determination of grazing capacity, and various systems of grazing as related to range-cattle production.}, keywords = {drought, improve economy, increase stability, prevention, Southwest, tragedy}, url = {/files/bibliography/029.pdf}, author = {R.S. Campbell} } @article {52636, title = {Range and cattle management during drought}, year = {1922}, month = {May 15, 1922}, pages = {84 }, institution = {Government Printing Office}, abstract = {

In the past, cattle production on Southwestern ranges has been a business with \"ups and downs,\" with prosperity or adversity governed by climatic conditions, which brought seasons of plenty in range forage and stock water followed by seasons of restricted forage growth and scarcity of water. Soon after the cattle business became established on the open public range of the Southwest, the herds were built up during a period of good years until the developed ranges were stocked fully or beyond the number they could carry even in good years. Then, at intervals, came dry periods, series of dry years with much less forage produced than was required by the stock on the range and with heavy losses from starvation. During the early days, before all the ranges had been opened up, there was opportunity to develop new range during such emergencies and, thus, to relieve the situation to some extent. Such possibilities diminished more and more, however, as practically all the range came into use. During the drought that ended in 1910, there was little opportunity of this nature and practically none in the drought of 1916 to 1918. The setback to the livestock industry, caused by the combination of unfavorable climatic conditions and unwise range practice, comes about mainly through heavy losses of stock, low calf crop, interference with improvement of breeding herds, retarded growth of young stock and range deterioration. During the last drought (1916 to 1918), according to estimates based on the best data obtainable, losses were at an average rate of 20 per cent annually for the three-year period and reached as high as 35 per cent in 1918, the worst year of the drought. Individual losses were as high as 50 per cent. The large reduction in calf crop is probably next in importance to losses. Natural increase is the main source of income, and if greatly reduced at a time when expenses are high, the result is serious. The calf crop for some of the ranges affected by the last drought was estimated at 35 per cent in 1917, 25 per cent in 1918 and 35 per cent in 1919, the three years most influenced by the drought. These figures are probably not far from representing the true situation. Drought also has been a prime factor in retarding improvement in the grade of stock. Heavy losses and forced sales might wipe out years of effort in building up the herd or reduce the numbers to an extent that culling and selection necessary to maintain quality would not be consistent with the importance of increasing the herd to take advantage of good years; or, the set-back might be such that it left the stockman financially unable to purchase the right kind of bulls.

}, keywords = {cattle management, drought, government publication, range management}, url = {/files/bibliography/008.pdf}, author = {Jardine, J. T. and Forsling, C.L.} }