This project is awarded under the Minority Postdoctoral Research Fellowships and Supporting Activities Program for 2006. The patchy distribution of vegetation across a landscape may result from the non-uniform allocation of limited resources, such as water and soil nutrients, as well as the effect of a disturbance, such as selective pressure from predators, competitors, or fire. The complex feedbacks between the physical and biotic environments need to be considered when developing management plans for conservation and restoration in heterogeneous ecosystems. I propose to examine the biotic and abiotic controls on the availability of an important plant nutrient in semi-arid South African savannas at Kruger National Park, to improve our understanding of soil-plant interactions and how they respond to fire and grazing. I will focus on silicon (Si), which is used as a plant-defense mechanism, and thus expected to be important in ecosystems dominated by herbivores. Silicon is also involved in enhancing plant growth and improves plants' ability to survive in nutrient poor soils or in the presence of toxic elements. My research will contribute to our understanding of the factors shaping heterogeneous distribution of vegetation which determines wildlife habitat at Kruger. The cycle of Si is linked to the carbon cycle, and to global climate, through the process of soil mineral weathering and Si's contribution to marine primary productivity. Very little is known about the role of grasslands in the global Si cycle. The application of isotope geochemistry to ecosystem ecology is revolutionizing our understanding of the processes that shape ecosystem structure and function. I am interested in the interactions between plants and their environment, especially soils, the atmosphere, and hydrology. Through my proposed post-doctoral research, I will gain training in new isotope techniques and geochemical methods that will allow me to better understand processes and underlying mechanisms controlling biogeochemical cycling. I expect to develop collaborations at my post-doctoral host institution, U.C. Santa Barbara (UCSB) under the mentorship of Dr. Oliver Chadwick, and in South Africa. I will join a small number of biogeochemists establishing new research programs with local scientists in Africa. I will also have the opportunity to participate in the training of the next generation of indigenous scientists and natural resource managers in a post-apartheid South Africa, by mentoring a graduate student from the University of the Witwatersrand. This opportunity will build upon my past mentoring experiences at U.C. Berkeley, and contribute to my preparation as a teacher and student advisor. I will build upon my past studies in Political Science to get students to think about the social and political context of scientific research and environmental management.
