• 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.
    • 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.
    • 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.
    • 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.
    • Rangeland Ecology & Management Index Volume 64, 2011

      Society for Range Management, 2011-11-01
    • 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.