Savannas and evergreen forests are the two most important tropical vegetation types on Earth, in terms of area, biodiversity, total carbon stocks, and use by humans. Understanding the processes that control the dynamics of savanna-forest boundaries is essential to predicting the long-term responses of tropical vegetation to changes in climate, fire, and human activity. The primary hypothesis of this study is that positive feedbacks have an overriding role in the dynamics of savanna-forest boundaries, and that these feedbacks are reinforced by the contrasting structural, physiological and ecological characteristics of savanna and forest trees. It is also hypothesized that the biological differences between savanna and forest species arose through an evolutionary feedback in which species' traits directly and indirectly influence the local environment, which in turn determines the selective pressures that drive the evolution of species' traits. To understand the feedbacks between plants and their physical environment, this project will integrate physiological measurements, experimental manipulations, studies of vegetation dynamics, and ecological modeling.
This research reinforces existing collaborations between researchers at the University of Brasilia and three US institutions. The project will provide Latin-American students with an opportunity to interact and collaborate with the investigators of this grant as well as with students from the US, and will provide research experiences for US undergraduate students. This will generate interest and expertise in tropical ecology while fostering interactions likely to grow into long-term collaborations. The project will sponsor a US high school biology teacher through a two-year career development program administered by the Kenan Institute designed to promote teacher leadership, teacher retention, and advance K-12 science.
