Climate and land-use influences on avifauna in central Argentina: Broad-scale patterns and implications of agricultural conversion for biodiversity

Climate and land use drive biodiversity patterns at large scales. Changes in these variables, either through increased atmospheric carbon dioxide concentrations or conversion of land to agriculture, will lead to broad-scale changes in species patterns at regional scales. In countries with developing economies, conversion of land to monocultures of highly valuable crops, such as soybeans, is already Occurring and is expected to increase in the future. Monitoring this change, as well as its impacts on important indicator species, such as birds, will provide insight into the rate and direction of these important changes. We used data from the first four years of a long-term monitoring program to relate broad-scale patterns in climate and land-use change to bird species richness and composition across land-use gradients in central Argentina. Results suggest that species richness is positively correlated with cover of native vegetation and negatively correlated with agricultural use. Predictor variables (including climate and land-use variables) explained 71% of the variation in species richness across the region. Bird species richness follows a gradient of temperature and precipitation across the region, with the hottest and wettest areas having the highest predicted species richness. Canonical correspondence analysis results show that raptors are found mainly in areas of agricultural use and, therefore, may be more vulnerable to agricultural practices and pesticide use. The results of this study suggest that continued conversion of native ecosystems to annual crops may lead to decreased overall richness of avifauna and possible important changes in species composition. (C) 2009 Elsevier B.V. All rights reserved.