Welcome to the Rangeland Ecology & Management archives. The journal Rangeland Ecology & Management (RE&M; v58, 2005-present) is the successor to the Journal of Range Management (JRM; v. 1-57, 1948-2004.) The archives provide public access, in a "rolling window" agreement with the Society for Range Management, to both titles (JRM and RE&M), from v.1 up to five years from the present year.

The most recent years of RE&M are available through membership in the Society for Range Management (SRM). Membership in SRM is a means to access current information and dialogue on rangeland management.

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Print ISSN: 0022-409x

Online ISSN: 1550-7424


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  • Rangeland Ecology & Management Index Volume 64, 2011

    Society for Range Management, 2011-11-01
  • Juniper Consumption Does Not Adversely Affect Meat Quality in Boer-Cross Goats

    Menchaca, Matthew W.; Scott, Cody B.; Braden, Kirk W.; Owens, Corey J.; Branham, Loree A. (Society for Range Management, 2011-11-01)
    Goat browsing can be used as an alternative brush management option for redberry (Juniperus pinchotii Sudw.) and ashe (Juniperus asheii Buch) juniper instead of more expensive and invasive brush control methods, assuming consumption of juniper does not adversely affect the marketability of offspring. Some wildlife species reportedly retain juniper flavor when consumed. We determined if juniper consumption affected meat quality or flavoring of Boer-cross kid carcasses. Twenty recently weaned, Boer-cross wethers were randomly assigned to one of four treatments with treatments fed different amounts of juniper (0%, 10%, 20%, 30% juniper in the diet). All goats were fed juniper for 28 d at the Angelo State University (ASU) Management, Instruction, and Research Center. All goats were also fed a feedlot ration to meet maintenance requirements (2% body weight). Juniper intake varied (P < 0.05) between all treatments (0%, 10%, 20%, 30%) primarily because treatments were fed different amounts of juniper. Following a 28-d trial, goats were harvested at the ASU Food Safety and Product Development Laboratory. Carcass characteristics including live weight, hot carcass weight, dressing percentage, loineye area, body wall fat thickness, and leg circumference were similar (P>0.05) among treatments. Sensory characteristics including tenderness, juiciness, flavor intensity, off-flavor, and overall acceptability were also similar (P > 0.05) among treatments. Landowners can utilize goats as a biological management tool without adversely affecting goat meat quality or flavoring.
  • Cattle Grazing Toxic Delphinium andersonii in South-Central Idaho

    Pfister, James A.; Cook, Daniel; Gardner, Dale R. (Society for Range Management, 2011-11-01)
    Anderson larkspur (Delphinium andersonii A. Gray) is a toxic plant responsible for cattle death losses in the western United States. The objectives of the present study were to determine when cattle consumed Anderson larkspur in relation to plant phenology and toxicity, and to determine if animal age influenced selection of Anderson larkspur. These grazing studies were conducted on semiarid sagebrush rangeland near Picabo, Idaho. Eight 6-7-yr-old mature Angus cows were used in 2008, whereas during 2009, 12 Angus cattle were used, including six yearling heifers and six 4-yr-old cows. The overall density of Anderson larkspur was 2.8 plants m-2 during 2008, and 4.9 plants m-2 during 2009. Total toxic alkaloid concentrations in Anderson larkspur plants were near or above 5 mg g-1 during both studies. During 2008 consumption peaked during the late flower and pod stage of growth. Overall in 2008 cows ate 3% of their bites as larkspur. During 2009 heifers ate about twice as much Anderson larkspur as did mature cows (5.1% of bites vs. 2.9%, respectively). Heifers repeatedly consumed sufficient larkspur that they collapsed; however, no animals were fatally intoxicated. Heifers appeared to become transiently averted to larkspur; however, heifers resumed consumption of D. andersonii after a period of one to several days of low or no consumption. Livestock management to reduce losses to Anderson larkspur should include timed grazing to avoid infested pastures during full flower to pod phenological stages, and grazing with older animals rather than yearling heifers.
  • Pyric-Herbivory and Cattle Performance in Grassland Ecosystems

    Limb, Ryan F.; Fuhlendorf, Samuel D.; Engle, David M.; Weir, Johhn R.; Elmore, R. Dwayne; Bidwell, Terrance G. (Society for Range Management, 2011-11-01)
    Achieving economically optimum livestock production on rangelands can conflict with conservation strategies that require lower stocking rate to maintain wildlife habitat. Combining the spatial and temporal interaction of fire and grazing (pyric- herbivory) is a conservation-based approach to management that increases rangeland biodiversity by creating heterogeneous vegetation structure and composition. However, livestock production under pyric-herbivory has not been reported. In both mixed-grass prairie and tallgrass prairie, we compared livestock production in pastures with traditional fire and grazing management (continuous grazing, with periodic fire on tallgrass prairie and without fire on mixed-grass prairie) and conservation-based management (pyric-herbivory applied through patch burning) at a moderate stocking rate. Stocker cattle weight gain, calf weight gain, and cow body condition score did not differ (P > 0.05) between traditional and conservation- based management at the tallgrass prairie site for the duration of the 8-yr study. At the mixed-grass prairie site, stocker cattle gain did not differ in the first 4 yr, but stocker cattle gained more (P < 0.05) on conservation-based management and remained 27% greater for the duration of the 11-yr study. Moreover, variation among years in cattle performance was less on pastures under conservation management. Traditional management in mixed-grass prairie did not include fire, the process that likely was associated with increased stocker cattle performance under conservation management. We conclude that pyric-herbivory is a conservation-based rangeland management strategy that returns fire to the landscape without reduced stocking rate, deferment, or rest.
  • Ecotypic Variation in Elymus elymoides subsp. brevifolius in the Northern Intermountain West

    Parsons, Matthew C.; Jones, Thomas A.; Larson, Steven R.; Mott, Ivan W.; Monaco, Thomas A. (Society for Range Management, 2011-11-01)
    Bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey) is an important native bunchgrass for rangeland restoration in western North America. This species is taxonomically complex and has diverged into as many as four subspecies, including subsp. brevifolius, for which four geographically distinct races have been described (A, B, C, and D). Of these four races, only C occurs in the northern Intermountain West. Our objectives were to describe phenotypic and genetic variation within C and to ascertain its taxonomic status. We evaluated 32 populations of C collected across the northern Intermountain West for a battery of biomass, phenological, and functional traits in common-garden settings in the field and greenhouse. Genetic variation was assessed with the use of amplified fragment length polymorphism (AFLP) markers, and correlations were calculated among phenotypic, genetic, environmental, and geographic distance matrices with the use of Mantel tests. Values for these four distance measures were positively correlated, suggesting that environmental heterogeneity and isolation by distance are shaping ecotypic divergence driven by natural selection. We describe three phenotypic zones for C that correspond to previously established ecoregion boundaries. Because genetic data group C apart from subsp. Brevifolius races A, B, and D, which originate in the Rocky Mountains and western Great Plains, the so-called race C merits description as a new subspecies apart from subsp. brevifolius.
  • Can Imazapic Increase Native Species Abundance in Cheatgrass (Bromus tectorum) Invaded Native Plant Communities?

    Elseroad, Adrien C.; Rudd, Nathan T. (Society for Range Management, 2011-11-01)
    Native plant communities invaded by cheatgrass (Bromus tectorum L.) are at risk of unnatural high intensity fires and conversion to cheatgrass monocultures. Management strategies that reduce cheatgrass abundance may potentially allow native species to expand and minimize further cheatgrass invasion. We tested whether the selective herbicide imazapic is effective in reducing cheatgrass and ‘‘releasing’’ native species in a semiarid grassland and shrub steppe in north-central Oregon. The experiment consisted of a completely randomized design with two treatments (sprayed with 70 g ai ha-1 of imazapic and unsprayed) and three replicates of each treatment applied to either 2.5 or 4 ha plots. We repeated this experiment in three different sites dominated by the following native species: 1) bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve ssp. spicata) and needle and thread (Hesperostipa comata [Trin. Rupr.] Barkworth), 2) needle and thread and Sandberg bluegrass (Poa secunda J. Presl), and 3) big sagebrush (Artemisia tridentata Nutt.). Nested frequency of all plant species in 1-m2 quadrats was collected for 1 yr pretreatment and 4 yr posttreatment. In all three sites, cheatgrass frequencies were significantly lower in sprayed plots than unsprayed plots for 3-4 yr posttreatment (P<0.1). Other annual plant species were also impacted by imazapic, but the effects were highly variable by species and site. Only two native perennial species, hoary tansyaster (Machaeranthera canescens [Pursh] Gray) and big sagebrush, increased in sprayed plots, and increases occurred only at two sites. These results suggest that a short-term reduction in cheatgrass alone is not an effective strategy for increasing the abundance of most native perennial plant species.
  • Topoedaphic Variability and Patch Burning in Sand Sagebrush Shrubland

    Winter, Stephen L.; Fuhlendorf, Samuel D.; Goad, Carla L.; Davis, Craig A.; Hickman, Karen R. (Society for Range Management, 2011-11-01)
    Patch burning is the deliberate application of fire to a management unit in a heterogeneous manner, resulting in the heterogeneous distribution of grazing animal impact. The application of patch burning typically has been discussed within a framework of imposing heterogeneity on a homogeneous landscape or management unit, yet most landscapes and management units are actually distinguished by an inherent level of heterogeneity. Within landscapes and management units, differing topography and soils interact to create patterns of contrasting patches, also known as topoedaphic sites. Thus, introduction of a heterogeneous disturbance such as patch burning on a landscape or management unit is more accurately described as the imposition of one layer of heterogeneity onto a pre-existing layer of heterogeneity. We examined effects of patch burning on vegetation structure and animal distribution across contrasting topographical sites in sand sagebrush (Artemisia filifolia Torr.) shrubland of the southern Great Plains in North America. Landscapes at our study site were characterized by an inherent amount of heterogeneity in vegetation structure due to variability in topoedaphic sites, and the patch burning treatment superimposed additional heterogeneity that was constrained by topoedaphic characteristics. Shrub-dominated sites were more dependent on patch burning for heterogeneity of vegetation structure than sites dominated by short grasses. Distribution patterns of cattle (Bos taurus) were not significantly different across treatments, though they followed patterns similar to previous studies. We demonstrated that heterogeneity was dependent on topoedaphic patterns and the application of patch burning management for heterogeneity was dependent on the inherent variability of a landscape.
  • Cattle Selection for Aspen and Meadow Vegetation: Implications for Restoration

    Jones, Bobette E.; Lile, David F.; Tate, Kenneth W. (Society for Range Management, 2011-11-01)
    There is concern over the decline of aspen and the lack of successful regeneration due to excessive browsing of aspen suckers by cattle and other wild and domestic ungulates. We conducted a 2-yr study on Lassen National Forest, California, to aid development of cattle grazing strategies to enhance aspen regeneration. We evaluated seasonal biomass, nutritional quality, and utilization by cattle of aspen suckers, aspen herbaceous understory vegetation, and meadow herbaceous vegetation within six aspen-meadow complexes. Aspen suckers had greater nutritional quality compared to aspen understory and meadow vegetation regardless of season or year. Nutritional quality declined with season in all three vegetation types. Early-growing season foraging by cattle focused on meadow and aspen understory vegetation. Mid-growing season decreases in meadow and aspen understory nutritional quality coincided with a marked increase in utilization of aspen suckers. By late-growing season, utilization on aspen suckers was significantly greater than aspen understory or meadow vegetation. Managers can use early-growing season grazing to reduce aspen consumption by cattle, set stocking rates so that adequate herbaceous vegetation is available throughout the growing season, provide nutritional supplements to reduce demand for nutritious aspen suckers, construct protective fencing, and implement grazing systems that insure years with mid- and late-growing season rest from heavy browsing.
  • Animal and Vegetation Response to Modified Intensive—Early Stocking on Shortgrass Rangeland

    Harmoney, Keith R.; Jaeger, John R. (Society for Range Management, 2011-11-01)
    A comparison of animal gains and vegetation trends was made from 2002-2008 between a continuous season-long stocking (SLS) system and a modified intensive-early stocking system (IES) with late-season grazing (IES 1.63 + 1; 1.6 times the number of animals of the SLS system from May 1 to July 15, and 1 times the number of animals of SLS from July 15 to October 1) on shortgrass native rangeland of western Kansas. The continuous season-long stocked system placed animals at a density of 1.37 ha steer-1 from May through October, or 2.63 animal unit months (AUM) ha-1, whereas the intensive-early stocked system with late-season grazing (3.33 AUM ha-1) stocked pastures at 0.85 ha steer-1 from May through the middle of July, and then stocked pastures at 1.37 ha steer-1 for the remainder of the grazing season by removing the heaviest animals mid-July each yr. Average daily gains (0.78 vs. 0.70 kg d-1, P = 0.039) and total animal gain (58 vs. 52 kg, P = 0.042) were different between the continuous season-long stocked and the intensive-early stocked animals during the first half of the grazing season. No difference was found between average daily gain (0.61 vs. 0.62 kg d-1, P = 0.726) and total animal gain (48 vs. 49 kg, P = 0.711) for the continuous season-long stocked and intensive-early stocked with late-season grazing animals during the last half of the season. Total individual animal gain (106 vs. 101 kg, P=0.154) and average daily gain (0.70 vs. 0.66 kg d-1, P = 0.152) was not different between the continuous season-long stocked and the intensive-early stocked system animals that were on pasture the entire grazing season. Total beef gain on a land-area basis (96 vs. 77 kg ha-1, P = 0.008) was greater for the modified intensive-early stocked system with late-season grazing with greater animal densities. Changes in residual biomass and most key vegetation components at the end of the grazing season were not different between the two systems.
  • Ranching and Multiyear Droughts in Utah: Production Impacts, Risk Perceptions, and Changes in Preparedness

    Coppock, D. Layne (Society for Range Management, 2011-11-01)
    Droughts characterize rangelands, yet drought research remains limited. Objectives of the study were to determine: 1) effects of the 1999-2004 drought on ranch resources, 2) how ranchers coped with the 1999-2004 drought, 3) whether ranchers have altered their preparedness for future drought, and 4) factors influencing change in preparedness. A phone and mail survey engaged a random sample of 615 ranchers providing 509 usable responses (83%). Data analysis employed descriptive statistics, directional change tests, and logistic regression. Compared to ‘‘normal’’ years, the 1999-2004 drought had negative effects on 75% of operations including major reductions in water supplies, forage, and cattle productivity. One quarter of respondents indicated that the drought had neutral or positive effects, usually because they had unhindered access to water or high-value hay. Only 14% of respondents felt they were adequately prepared for the 1999-2004 drought, illustrated by the high use of federal relief programs and involvement in crisis-related water development, livestock sales, and hay purchases. The ‘‘drought trap’’ was financial (lower revenue and higher costs), with effects well beyond 2004. By 2009 preparedness had reportedly changed. Twenty-nine percent of respondents felt they were better prepared for drought in 2009 than in 1998, a significant shift (P<0.01) in the population. Increased preparedness was significantly associated (P<0.02) with how badly a rancher was affected by the 1999-2004 drought as well as their belief that another drought is imminent. Risk-management tactics now include investment in natural-resource development and conservation plans, reductions in stocking rates, income diversification, and enrollment in insurance and federal disaster-assistance programs. Sixty-one percent of respondents said they were actively planning for future drought. The lessons of 1999-2004 have increased awareness of drought hazards among Utah ranchers, providing opportunity to enhance the financial and ecological sustainability of ranching via well-conceived risk-management initiatives.
  • An Assessment of State-and-Transition Models: Perceptions Following Two Decades of Development and Implementation

    Knapp, Corrine N.; Fernandez-Gimenez, Maria E.; Briske, David D.; Wu, X. Ben (Society for Range Management, 2011-11-01)
    State-and-transition models (STMs) are being developed for many areas in the United States and represent an important tool for assessing and managing public and private rangelands. Substantial resources have been invested in model development, yet minimal efforts have been made to evaluate the utility of STMs for rangeland assessment and management. We interviewed 47 rangeland professionals, equally divided between managers and researchers, in four ecoregions to determine their perceptions of the purpose, development, and strengths and weaknesses of STMs to assess the status of the STM framework. Our analysis identified three primary perspectives regarding the purpose of STMs: a decision-making tool for land managers, a means to represent the complex dynamics of rangeland ecosystems, and an effective communication tool. These diverse views of STM purposes were associated with differing perspectives concerning model development that identified five major issues in need of further development and refinement: 1) the relative importance of management practices and ecological processes in driving transitions, 2) the criteria used to define thresholds, 3) the appropriate level of model complexity, 4) the respective roles of expert knowledge and ecological data in model development, and 5) processes for model review and revision. We recommend greater dialogue among researchers and managers to further clarify STM terminology and develop standard protocols for model development and validation. Mechanisms are critically needed to assure peer review and revision of existing models so that STMs are continually updated to reflect current understanding of rangeland dynamics.
  • Extent of Coterminous US Rangelands: Quantifying Implications of Differing Agency Perspectives

    Reeves, Matthew Clark; Mitchell, John E. (Society for Range Management, 2011-11-01)
    Rangeland extent is an important factor for evaluating critical indicators of rangeland sustainability. Rangeland areal extent was determined for the coterminous United States in a geospatial framework by evaluating spatially explicit data from the Landscape Fire and Resource Management Planning Tools (LANDFIRE) project describing historic and current vegetative composition, average height, and average cover through the viewpoints of the Natural Resources Inventory (NRI) administered by the Natural Resources Conservation Service and the Forest Inventory and Analysis (FIA) program administered by the US Forest Service. Three types of rangelands were differentiated using the NRI definition encompassing rangelands, afforested rangelands, and transitory rangelands. Limitations in the FIA definition permitted characterization of only two rangeland types: rangeland and rangeland vegetation with a small patch size. These classes were similar to those from the NRI definition but differed in tree canopy cover threshold requirements. Estimated rangeland area resulting from the NRI- and FIA-LANDFIRE models were 268 and 207 Mha, respectively. In addition, the NRI-LANDFIRE model identified 19 Mha of afforested rangelands due principally to encroachment and increased density by species classified as trees belonging to the genera Quercus, Prosopis, and Juniperus. The biggest discrepancies between acreage estimates derived from NRI- and FIA-LANDFIRE models occurred in oak, pinyon-juniper, and mesquite woodlands. The differences in area estimates between the NRI and FIA perspectives demonstrate the need for development of unified, objective methods for determining rangeland extent that can be applied consistently to all rangelands regardless of ownership or jurisdiction. While the models and geospatial information developed here are useful for national-scale estimates of rangeland extent, they are subject to the limitations of the LANDFIRE data products./La extensión de los pastizales es un importante factor para evaluar indicadores críticos de la sustentabilidad de estas aéreas. La extensión aérea de los pastizales se determinó por los colindantes de Estados Unidos (US) en un marco geoespacial para evaluar espacialmente los datos explícitos del proyecto LANDFIRE describiendo su composición botánica histórica y actual, altura promedio, y cobertura promedio mediante el uso los criterios desarrollados por el Natural Resources Inventory (NRI) administrado por el Natural Resources Conservation Service y el Forest Inventory and Analysis Program (FIA) administrado por el US Forest Service. Tres tipos de pastizales se evaluaron usando la definición del NRI abarcando: pastizales, pastizales forestados y pastizales transitorios. Limitaciones en la definición de la FIA solo permiten la caracterización de dos tipos de pastizales: pastizales y vegetación con pequeñas areas de pastizal. Estas clases fueron similares a aquellas de la definición de NRI pero difirieron en los requerimientos de la cubierta aérea de los árboles. Las areas de pastizal estimadas usando los modelos NRI y FIA-LANDFIRE fueron 268 y 207 Mha, respectivamente. Además, el modelo NRI-LANDFIRE identificó 19 Mha de pastizales forestados principalmente debido a la invasión y el incremento de la densidad de especies clasificadas como arboles pertenecientes al género Quercus, Prosopis, y Juniperus. Las mayores discrepancias entre la estimación de superficie generadas por los modelos NRI y FIA-LANDFIRE se identificaron en bosques de encino, piñón-junípero y mezquite. Las diferencias entre las estimaciones de perspectivas aéreas generadas entre los modelos NRI y FIA demostraron la necesidad de desarrollar un modelo unificado; los métodos objetivos para determinar la condición de los pastizales pueden aplicarse consistentemente a todos los pastizales sin importar propiedad y jurisdicción. Mientras que los modelos e información geoespacial desarrollados aquí son útiles para la estimación a escala nacional de la condición de los pastizales, aunque están sujetas a la limitación de los productos de datos generados por LANDFIRE.
  • Energy and Carbon Costs of Selected Cow-Calf Systems

    Zilverberg, Cody J.; Johnson, Philip; Weinheimer, Justin; Allen, Vivien G. (Society for Range Management, 2011-11-01)
    Fossil fuel-derived inputs can increase cow-calf production per unit of land or labor but can raise financial and environmental concerns. Eleven US cow-calf systems from nine ecological regions in Iowa, South Dakota, Tennessee, and Texas were analyzed to determine quantities of energy used and carbon (C) emitted due to fossil fuel use (excluding emissions from soils and biota) and to determine how management and environment influenced those quantities. Total energy and C cost, calculated cow-1 or ha-1, were highly correlated (0.99). Energy use cow-1 and ha-1 varied greatly across systems, ranging from 3 000 to 12 600 megajoules (MJ) cow-1 yr-1 and from 260 to 20 800 MJ ha-1 yr-1. As stocking rate increased, MJ cow-1 increased at an increasing rate. Differences in quantity of fertilizer accounted for most variation in energy use. Fertilizer allowed higher stocking rates but reduced energy efficiency of liveweight marketed. Compared to intensive, higher stocking rate systems, rangeland systems based on native or naturalized forages used little or no fertilizer, but used more energy cow-1 for crude protein (CP) supplementation, fencing, and pickup trucks. Across all systems, energy used to produce winter feed ranged from 0% to 46% of total energy. Northern systems used higher percentages of total energy for winter feed and fed for more days year-1, but southern systems that included large amounts of bermudagrass (Cynodon dactylon L.) hay used the most MJ cow-1 for winter feed. Systems with high MJ cow-1 were vulnerable to shocks in energy prices. Reducing energy use and C emissions from cow- calf operations is possible, especially by reducing fertilizer and hay use, but would likely reduce productivity ha-1. Forages with high nitrogen use efficiency, locally adapted plants and animals, and replacement of hay with unfertilized dormant forage and CP supplementation could reduce energy use./Insumos derivados de los combustibles fósiles pueden incrementar el costo por unidad de tierra o trabajo dentro del sistema vaca-becerro pero a la vez pueden incrementar las preocupaciones financieras y medioambientales. Once sistemas de producción vaca-becerro de 9 regiones ecológicas de Estados Unidos ubicadas en Iowa, Dakota del Sur, Tennessee, y Texas se analizaron para determinar las cantidades de energía consumidas y el carbono (C) emitido debido al uso de combustibles fósiles (exceptuando las emisiones inherentes al suelo y al medioambiente), y a la vez determinar como el manejo y el medioambiente afecta estas cantidades. El total de energía y costo de carbón C, calculado por vaca o hectárea fue altamente relacionado (0.99). El uso de energía por vaca y hectárea tuvo una gran variación en los sistemas, fluctuando de 3 000 o 12 600 MJ vaca-1 año-1 y de 260 a 20 800 MJ ha-1 año-1. Mientas, la densidad animal incrementaba MJ vaca-1 también se incrementó a una tasa a la alza. Las diferencias en cantidad de fertilizante fueron las que provocaron una mayor variación en uso de energía. El uso de fertilizante permite una alta densidad de animales pero reduce la eficiencia energética del peso vivo comercializado. En comparación con el uso intensivo, sistemas de alta carga animal, sistemas de pastoreo basados en forrajes nativos o naturalizados usan una pequeña cantidad o no fertilizante en absoluto, pero a su vez usan más energía vaca-1 debido a la suplementación de proteína cruda, alambrado, y uso de vehículos. En todos los sistemas, la energía usada para producir alimentos durante el invierno fluctúo de un0% a 46% del total de la energía consumida. Los sistemas del norte del país usan mayores porcentajes del total de la energía consumida para proveer alimentación durante el invierno por mas días al año-1, mientras que los sistemas del sur que incluyen grandes cantidades de heno de pasto bermuda (Cynodon dactylon L.) usan la mayor cantidad de MJ vaca-1 para alimentación durante el invierno. Los sistemas con alto MJ vaca-1 fueron los más vulnerables a cambios bruscos en los precios de energía. La reducción del uso de energía y las emisiones de C en los sistemas de producción vaca-becerro es posible, especialmente mediante la reducción de fertilización y uso de heno, aunque podría ocasionar reducción en la productividad ha-1. Los forrajes con alta eficiencia en el uso de nitrógeno, así como plantas y animales adaptados a las condiciones locales, y el reemplazo de heno por forrajes no fertilizados y el uso de suplementación proteica podría reducir el uso de energía.
  • Incorporating Biodiversity Into Rangeland Health: Plant Species Richness and Diversity in Great Plains Grasslands

    Symstad, Amy J.; Jones, Jayne L. (Society for Range Management, 2011-11-01)
    Indicators of rangeland health generally do not include a measure of biodiversity. Increasing attention to maintaining biodiversity in rangelands suggests that this omission should be reconsidered, and plant species richness and diversity are two metrics that may be useful and appropriate. Ideally, their response to a variety of anthropogenic and natural drivers in the ecosystem of interest would be clearly understood, thereby providing a means to diagnose the cause of decline in an ecosystem. Conceptual ecological models based on ecological principles and hypotheses provide a framework for this understanding, but these models must be supported by empirical evidence if they are to be used for decision making. To that end, we synthesize results from published studies regarding the responses of plant species richness and diversity to drivers that are of management concern in Great Plains grasslands, one of North America’s most imperiled ecosystems. In the published literature, moderate grazing generally has a positive effect on these metrics in tallgrass prairie and a neutral to negative effect in shortgrass prairie. The largest published effects on richness and diversity were caused by moderate grazing in tallgrass prairies and nitrogen fertilization in shortgrass prairies. Although weather is often cited as the reason for considerable annual fluctuations in richness and diversity, little information about the responses of these metrics to weather is available. Responses of the two metrics often diverged, reflecting differences in their sensitivity to different types of changes in the plant community. Although sufficient information has not yet been published for these metrics to meet all the criteria of a good indicator in Great Plains Grasslands, augmenting current methods of evaluating rangeland health with a measure of plant species richness would reduce these shortcomings and provide information critical to managing for biodiversity./Los indicadores de la salud de los pastizales generalmente no incluyen una medida de la biodiversidad. El aumento en la atención de mantener la biodiversidad en los pastizales sugiere que esta omisión sea reconsiderada. La riqueza y la diversidad delas especies de plantas son dos parámetros que pueden ser muy u ́tiles y apropiados. Idealmente, su respuesta a una variedad de factores antropogénicos y naturales en el ecosistema de interés se podría entender claramente, proporcionando los medios para diagnosticar la causa del detrimento del ecosistema. Los modelos ecológicos conceptuales basados en principios e hipótesis ecológicos proporcionan un marco para esta comprensión, pero estos modelos deben ser apoyados por evidencias empíricas si van a ser utilizados para la toma de decisiones. De tal manera, resumimos los resultados de estudios publicados con respecto a las respuestas de la riqueza y de la diversidad de las especies de plantas y los factores que son de preocupación a los manejador es de los pastizales de las grandes planicies, uno de los ecosistemas más amenazado de Norte América. En la literatura publicada, el pastoreo moderado generalmente tiene un efecto positivo en estos parámetros en los pastizales altos y un efecto neutro o negativo en los pastizales cortos. La mayoría de las publicaciones sobre la riqueza y diversidad de los pastizales fueron causadas por el pastoreo moderado en los pastizales altos y la fertilización de nitrógeno en los pastizales cortos. Aunque, el clima se cita frecuentemente como la razón de las fluctuaciones anuales considerables en la riqueza y la diversidad, poca información sobre las respuestas de estos parámetros al clima está disponible. Las respuestas de los dos parámetros difirieron a menudo, reflejando discrepancias en su sensibilidad a diversos tipos de cambios en la comunidad de la planta. Aunque suficiente información todavía no se ha publicado para que estos dos parámetros cubran todos los criterios de un buen indicador de los pastizales de las grandes planicies, el incluir en los métodos actuales de evaluación de la salud de los pastizales, una medida de riqueza de las especies de las plantas reduciría estos defectos y proporcionaría la información crítica para el manejo de la biodiversidad.
  • Rebuttal: Disturbance to Surface Lithic Components of Archaeological Sites by Drill Seeding

    Rust, Jeffrey A.; Earl, Dale (Society for Range Management, 2011-09-01)
  • Condensed Tannin in Drinking Water Reduces Greenhouse Gas Precursor Urea in Sheep and Cattle Urine

    Kronberg, Scott L.; Leibig, Mark A. (Society for Range Management, 2011-09-01)
    Ingestion of small amounts of condensed tannin (CT) by ruminants may provide benefits including reduction of ammonia and nitrous oxide emissions by reducing urine urea excretion. However, providing grazing ruminants with sufficient amounts of CT- containing forages is difficult, and an alternative may be to provide CT in their drinking water. We conducted three trials to determine if urine urea levels in sheep and cattle decrease after they drink water containing CT. In two initial trials, blood serum urea was measured as a surrogate for urine urea when lambs or steers drank tap water containing low to higher amounts of quebracho tannin (QT). Serum urea concentration was measured after lambs drank the treatments for 7 d or steers for 4-6 d. Lambs consumed pellets (16% crude protein [CP] as fed) at 3.5% of body weight, and steers were fed cubes (15% CP as fed) at 3% of body weight. Mean serum urea concentration in sheep was reduced when they consumed water with QT (P = 0.03) and was also reduced for cattle (P < 0.001). In a third trial with a Latin-square design, four wethers were fed pellets (22% CP, DM basis) and given tap water or tap water with low, medium, or high amounts of QT, and their urine urea excretion was measured. There was a linear effect of QT intake on daily urine urea excretion as a percentage of nitrogen intake (P = 0.03). Reductions in daily urea excretion as a percentage of nitrogen intake were 3.5%, 6.6%, and 12.6%, respectively, for the low, medium, and high QT intake. Small amounts of QT in the drinking water of grazing ruminants can reduce their urine urea excretion./La ingestión de pequen ̃as cantidades de taninos concentrados (TC) por los rumiantes podría traer beneficios incluyendo, la reducción de emisiones de amonia y oxido nitroso al reducir la excreción de urea por la orina. Sin embargo, proveer a los rumiantes en pastoreo con suficiente cantidad de TC en el forraje es difícil y una alternativa podría ser agregar el TC en los abrevaderos. Realizamos tres pruebas para determinar sí el nivel de urea en la orina en ovinos y bovinos disminuía después que estos animales bebieran agua con TC. En dos pruebas iniciales, se medio suero sanguino con urea como sustituto de orina de corderos y novillos que bebieron agua conteniendo baja y alta cantidad de tanino de quebracho (TQ). Se midió el suero de urea concentrado después de que los corderos bebieron del tratamiento por 7 días y los novillos de 4 a 6 días. Los corderos consumieron el 3.5% de su peso vivo de suplemento en forma de pellets (16% de PC) y los novillos suplemento en forma de cubos (15% de PC) en cantidad correspondiente al 3% de su peso vivo. La media de la concentración de suero de urea en borregas se redujo cuando consumieron agua con TQ (P = 0.03), y también se redujo en bovinos (P < 0.001). En una tercera prueba con diseño de Cuadro Latino, cuatro corderos se alimentaron con pellets (22% PC, en base a materia seca) y tuvieron acceso a agua sin TQ o agua con cantidades bajo, media y alto de TQ y se medio las excreciones de urea en la orina. Hubo un efecto linear en el consumo de TQ y las excreciones diarias de urea en la orina como un porcentaje del consumo de nitrógeno (P=0.03). La reducción de excreciones diarias de urea en la orina como porcentaje de consume de nitrógeno fueron 3.5%, 6.6%, y 12.6% respectivamente para el bajo, medio y alto consumo de TQ. Cantidades pequeñas de TQ en el agua de beber para ovinos en pastoreo puede reducir la excreción de urea en la orina.
  • Understory Vegetation and Ponderosa Pine Abundance in Eastern Oregon

    Carr, Craig A.; Krueger, William C. (Society for Range Management, 2011-09-01)
    Management prescriptions for contemporary ponderosa pine (Pinus ponderosa Dougl.) forests often incorporate the restoration to a structure that more closely resembles pre-European contact forests. Successful restoration programs should incorporate the herbaceous understory component; however, published research specifically addressing changes in understory species composition is minimal. Ponderosa pine influence on the undercanopy environment may be an important factor in understory vegetation distribution. In this study, we addressed the relationships among ponderosa pine abundance, undercanopy environment, and understory species composition and made inferences with respect to restoration potential. Data representing vegetation, soil, and environmental attributes were measured in 28 plots in an eastern Oregon ponderosa pine forest. Relationships among the parameters measured were evaluated using cluster analysis, indicator species analysis, and ordination. Ponderosa pine occupancy was inversely related to understory perennial bunchgrass abundance and species diversity and appeared to regulate the undercanopy habitat through alterations in light intensity, nitrogen availability, and soil temperature. Light availability was the most important ponderosa pine-influenced undercanopy environmental parameter associated with understory vegetation distribution. These data suggested that degradation in the undercanopy environment associated with higher levels of ponderosa pine abundance may be temporary and that restoration practices that reduce pine occupancy should promote undercanopy conditions favorable to perennial bunchgrass growth. However, understory vegetation recovery in stands with excessive pine ingrowth may be constrained by desired understory species loss or invasion by more competitive understory vegetation.
  • Comparison of Unmanned Aerial Vehicle Platforms for Assessing Vegetation Cover in Sagebrush Steppe Ecosystems

    Breckenridge, Robert P.; Dakins, Maxine; Bunting, Stephen; Harbour, Jerry L.; White, Sera (Society for Range Management, 2011-09-01)
    In this study, the use of unmanned aerial vehicles (UAVs) as a quick and safe method for monitoring biotic resources was evaluated. Vegetation cover and the amount of bare ground are important factors in understanding the sustainability of many ecosystems. Methods that improve speed and cost efficiency could greatly improve how biotic resources are monitored on western lands. Sagebrush steppe ecosystems provide important habitat for a variety of species including sage grouse and pygmy rabbit. Improved methods of monitoring these habitats are needed because not enough resource specialists or funds are available for comprehensive on-the-ground evaluations. In this project, two UAV platforms, fixed-wing and helicopter, were used to collect still-frame imagery to assess vegetation cover in sagebrush steppe ecosystems. This paper discusses the process for collecting and analyzing imagery from the UAVs to 1) estimate percentage of cover for six different vegetation types (shrub, dead shrub, grass, forb, litter, and bare ground) and 2) locate sage grouse using representative decoys. The field plots were located on the Idaho National Laboratory site west of Idaho Falls, Idaho, in areas with varying amounts and types of vegetation cover. A software program called SamplePoint was used along with visual inspection to evaluate percentage of cover for the six cover types. Results were compared against standard field measurements to assess accuracy. The comparison of fixed-wing and helicopter UAV technology against field estimates shows good agreement for the measurement of bare ground. This study shows that if a high degree of detail and data accuracy is desired, then a helicopter UAV may be a good platform to use. If the data collection objective is to assess broad-scale landscape level changes, then the collection of imagery with a fixed-wing system is probably more appropriate./En este estudio se evaluó el uso de vehículos aéreos no tripulados (VANT) como un método rápido y seguro para monitorear recursos bióticos. La cubierta vegetal y la cantidad de suelo desnudo son factores importantes para entender la sustentabilidad de varios ecosistemas. Métodos que mejoren la rapidez y el costo podrían mejorar la manera en que los recursos bióticos de las tierras del oeste son monitoreados. El ecosistema de estepa de artemisa provee hábitat para varias especies que incluyen al ganso sage y conejo pigmeo. Es necesario mejorar los métodos de monitoreo de estos hábitat porque no hay suficientes especialistas en recursos o fondos disponibles para evaluaciones completas en el terreno. En este proyecto, se utilizaron dos plataformas de VANT, alas fijas y helicóptero para recolectar imágenes fotográficas para evaluar la cubierta vegetal en un ecosistema de estepa de artemisa. En este artículo se discute el proceso de recolección y análisis de imágenes de un VANT para 1) estimar el porcentaje de cubierta de seis diferentes tipos de vegetación (matorral, matorral seco, zacate, hierbas, mantillo y suelo desnudo) y 2) ubicar gansos sage usando señuelos. Las parcelas experimentales se ubicaron en el Laboratorio Nacional de Idaho sitio localizado en Idaho Falls, Idaho en áreas con diferentes cantidades y tipos de cubierta vegetal. Se uso el programa de software SamplePoint junto con inspecciones oculares para evaluar el porcentaje de cubierta de seis tipos de cubiertas. Los resultados se compararon contra medidas de campo estándar para evaluar su precisión. La comparación de la tecnología de helicóptero VANT y alas fijas contra estimaciones de campo muestra buena relación para las medidas de suelo desnudo. El estudio muestra que sí se requiere alto grado de detalle y precisión en los datos el helicóptero VANT podría ser una buena plataforma para usarse. Pero sí el objetivo de recopilación de datos, es evaluar a gran escala los niveles de cambio en el paisaje entonces, la recopilación de imágenes con el sistema de alas fijas es probablemente más apropiado.

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