Rates, patterns and causes of vegetation change in the Gran Sabana, Venezuela

点击翻译按钮获取中文摘要

Savannas are defined as tropical ecosystems with a continuous grass layer and a discontinuous tree layer. At high rainfall sites savannas border onto forests, or exist in a mosaic of forest and savanna. In this study we propose to investigate the whether climate, fire or management practices can explain changes in the cover of forest and savanna vegetation in tropical regions with seasonal climates. Understanding these controls is critical for predicting future patterns of carbon storage in tropical systems. Our study system, the Gran Sabana, Venezuela, is a high rainfall site where savanna and forest form a mosaic. Previous work suggests that edaphic factors do not control this mosaic, hence the study system is well suited exploring climate, fire and management controls on savanna - forest dynamics. We propose to use remote sensing and stable carbon isotope methods to describe both recent and longer term changes in forest and savanna cover. A combination of statistical analyses and dynamic modelling will be used to explore whether climate, fire, or management practices best explain observed forest - savanna dynamics. We are aware of no studies that have used a combination of stable carbon isotope, remote sensing and dynamic modelling to explore interactions between savannas and forests. Hence we believe that our study will yield novel insights that will improve our predictive understanding of the interactions between savannas and forests.