Estimated effects of climate change on grassland production and legume content across southern Australia

摘要

Climate changes caused by anthropogenic increases in greenhouse gases such as CO_2 will affect southern Australia along with the rest of the globe. Dryland pastures supporting extensive beef, sheepmeat and wool production occupy a third of southern Australia's farming zone. These livestock production systems are highly sensitive to climatic variation, because they depend almost entirely on pasture as their source of feed. Given the diversity of current climates, soils and pastures that are found across southern Australia, and the spatial variation in projected climate changes (CSIRO 2007), it can also be expected that the impacts of changing climates on pasture production will differ across space. Annual and perennial forage legumes arc an importantpart of the feedbase across most of southern Australia; experimental research suggests that legumes are likely to be favoured by increasing atmospheric CO_2 concentrations (e.g. Clark et al. 1997) and it is therefore possible that higher legume contentin grasslands might be one positive effect of global climate change. In this study, therefore, we have modelled grassland and livestock production to examine the changes in amount, seasonal distribution and legume content of grass-based pastures at locations across southern Australia under climates projected for 2030, 2050 and 2070.