Climate-growth relations of Aspidosperma pyrifolium; assessing future responses to climate change by use of tree rings

Abstract

Understanding the effects of climate change on tropical tree growth and functioning is essential because of the importance of tropical forests in global biogeochemical cycles, carbon stocks, ecosystem service provision. Dendrochronological studies are becoming more common in tropical regions and several species have proven annual growth ring formation. In the Caatinga biome, Aspidosperma pyrifolium is a species with great potential for dendrochronological studies, as it forms annual rings and has a wide geographic distribution. This combination allows for tree-ring studies along gradients, allowing spatio-temporal evaluations of the effects of environmental factors on growth variability of the species. The objective of this study is to evaluate the relationship between interannual variability in environmental factors and tree growth of Aspidosperma pyrifolium over time in localities with contrasting climates and soils within the Caatinga biome. We will evaluate how interannual variation in ring width is influenced by interannual variability in local (precipitation and temperature) and global (El Niño events, ocean surface temperatures) climate variables. We will also assess how these responses are modulated by environmental gradients, seeking to understand how trees will respond to future climate change in the region. With these questions we hope to develop robust chronologies of past growth variability of the species. We also hope to improve our understanding of tree-growth responses to climate change over recent decades in the Caatinga, and how these responses are modulated by soil nutrients and climatic gradients.