Incorporating Precipitation-Induced Variation in Annual Forage Production Into Economic Analyses of Range Improvement Practices.

20 p

Integrated Brush Management Systems for South Texas: Development and Implementation.

76 p

Biophysical and economic models for assessing impacts of change on grazingland ecosystems Modelos biofísicos e econômicos para avaliar impactos de mudanças no ecossistema pastagem nativa

PHYGROW, a hydrologic-based forage simulation model, was parameterized to represent a typical South Texas ranch engaged in the production of cattle and meat goats with an indigenous population of white-tailed deer. Forage production and associated stocking rates for two cattle:goat ratios were simulated with POPMIX for 20 years. Two ten-year weather scenarios, one representing normal conditions (30% drought years) and one representing dryer weather conditions (50% drought years) were analyzed. Management decision rules (ASPC) were developed for the region to produce estimates of annual animal production and operating costs for the enterprises on each of the four scenarios. These performance and cost data were then used as input into FLIPSIM, a firm level income and policy simulator, along with relevant product and input price data for the region. Integration of modeled results produced useful information showing the socioeconomic consequences for a typical South Texas firm impacted by alternative climatic conditions and management strategies.<br>Um modelo de simulação de produção de forragem (PHYGROW), foi parametrizado para representar uma fazenda típica no Sul do Texas envolvida com a produção de bovinos, caprinos e de animais silvestres (cervo). A produção de forragem e as taxas de lotação associadas a bovinos e caprinos foram simuladas com POPMIX para o período de 20 anos. Dois períodos de dez anos, um representando condições normais de tempo (30% da série de anos secos) e outro representando condições de tempo mais secos (50%) foram analisados. Foram desenvolvidas regras de decisão de manejo (ASPC) para a região visando estimar a produção anual dos animais e custo operacional para as atividades em cada um dos quatro cenários. Os dados de performance animal e de custo foram então usados como input no FLIPSIM, um simulador de renda e de estratégias de manejo a nível de fazenda, juntamente com dados relevantes de produtos e preços para a região do estudo. A integração dos modelos produziu informações úteis e serviu para mostrar as conseqüências socioeconômicas das diferentes condições climáticas e de alternativas estratégias de manejo para uma fazenda típica no Sul do Texas

Livestock early warning information resource in the Horn of Africa: Forage and livestock marketing information analysis and forecasts

The Livestock Early Warning System (LEWS) project, now transformed into the Livestock Information Network and Knowledge System (LINKS), of the Global Livestock Collaborative Research Support Program led by Texas A&M University has developed robust forage monitoring and livestock market information systems covering the eastern African region. The two systems systematically and continuously collect and deliver timely information on forage supplies, and forecast livestock market prices and volume trends to stakeholders. The analysis and the suite of products generated are intended to enable pastoral communities to respond to crises and thus protect livelihoods, communities'; assets and their ability to subsist in harsh environments, by triggering appropriate and timely responses. This article describes the development methodology, implementation structure and application of these early warning products

Genetic variation between ecotypic populations of Chloris roxburghiana grass detected through RAPD analysis

Chloris roxburghiana is an important rangeland grass in Kenya. In some areas it has disappeared due to land degradation resulting from overgrazing and drought. Efforts to re-introduce the grass through re-seeding using seeds from research stations have had little success. One possible reason for low establishment is attributed to transplanting spatially separated populations that may represent genetically distinct ecotypes. To test this hypothesis, germplasm diversity within and among four populations of C. roxburghiana from four ecologically distinct sites was analysed using random amplified polymorphic DNA (RAPD) markers. A total of 131 polymorphic markers were identified using nine RAPD primers. There was significant variation among populations, with genetic diversity (H) ranging from 0.134 to 0.206. Analysis of molecular variance (AMOVA) revealed most variance within populations (76%). However, the variation among populations was also significant (24%). The UPGMA of the population frequency indicated that the four populations of C. roxburghiana were genetically distinct, probably as a result of variation in soil fertility, geographical isolation and socio-ecological history of the study sites. Although there are differences for neutral genetic markers between the populations, it is difficult to relate this directly to ecotype since correlation does not imply causality. The implication for optimising future seed collection is discussed and potential areas for further studies identified