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

热带稀树草原被定义为具有连续的草层和不连续的乔木层的热带生态系统。在降雨量大的地方，稀树大草原与森林接壤，或者存在于森林和稀树大草原的镶嵌之中。在这项研究中，我们建议调查气候、火灾或管理措施是否可以解释热带季节性气候地区森林和稀树草原植被覆盖的变化。了解这些控制对于预测热带系统未来的碳储存模式至关重要。我们的研究系统，委内瑞拉的Gran Sabana，是一个降雨量很大的地点，在那里稀树草原和森林形成了马赛克。以前的工作表明，土壤因素不能控制这种镶嵌，因此该研究系统非常适合探索气候、火灾和管理对稀树草原森林动态的控制。我们建议使用遥感和稳定碳同位素方法来描述森林和稀树草原覆盖的近期和长期变化。将使用统计分析和动态建模相结合的方法来探索气候、火灾或管理实践是否最好地解释了观察到的森林稀树草原动态。据我们所知，还没有研究使用稳定碳同位素、遥感和动态建模相结合的方法来探索稀树草原和森林之间的相互作用。因此，我们相信，我们的研究将产生新的见解，将提高我们对稀树草原和森林之间相互作用的预测性理解。

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.