A national analysis of the potential effects of climate change on rangeland ecosystems.

摘要

In spite of the uncertainties of potential climate change, a scientific consensus is emerging that increasing concentrations of atmospheric CO{dollar}sb2{dollar} could alter global temperatures and precipitation patterns. Changes in global climate as predicted by general circulation models (GCM) could, therefore, have profound implications for global agriculture. The objective of this study was to assess the impacts of potential climate change on livestock and grassland production in the major producing regions of the United States. Simulation sites were selected for the study on the basis of the region's economic dependence on rangeland livestock production. Five thirty-year simulations per site using the SPUR (Simulation of Production and Utilization of Rangelands) and CBCPM (Colorado Beef Cattle Production Model) models were conducted. Climate change files were obtained by combining historical weather data from each site with predicted output from three GCM's. Results from nominal runs were compared with the three climate change scenarios and a doubled CO{dollar}sb2{dollar} run. The magnitude and direction of ecosystem response to climate change varied among the GCM's and by geographic region. Simulations showed that changes in temperature and precipitation caused an increase in aboveground net primary production for most sites. Increased decomposition rates were recorded for northern regions. Rise in early season temperature lengthened the growing season. Consequently, changes in the amount and timing of supplemental forage for livestock were observed. In northern regions animal production increased which would imply an increase in economic survivability. However, economic survivability in southern regions is less certain. Large decreases in animal production indicator variables were recorded for the southern regions.