Spatiotemporal Dynamics of Woody Cover in a Savanna Landscape

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Savanna ecosystems cover vast areas of the earth's land surface and play a key role in biogeochemical cycling by providing habitat for wildlife and resources for rural communities. Empirical evidence and modeling efforts suggest that many of these grass-dominated ecosystems are becoming woodier over time and that these changes will have profound effects on a wide range of ecological and socio-ecological processes of their regions. This research project will analyze the ecological mechanisms and spatial interactions that underpin the process of woody cover change in grassland and savanna systems over the past two decades. The project will provide new perspectives about the impacts that changes in these ecosystems will have in altering their functions including soil moisture dynamics, radiation, soil temperature and nutrients, and carbon cycling and storage. The insights from this project will advance basic understanding about the fundamental forces driving woody cover change across a wide range of environmental settings. Project results will help guide policy makers, governmental agencies, and resource administrators in assessing appropriate courses of action. This project also will strengthen international research collaborations among U.S. and African scientists and institutions.Interactions between grassland and woody vegetation in a savanna ecosystem depend on the spatial context where even a small change at a fine-scale may have large-scale landscape-level ramifications of modifying entire vegetation distribution patterns. Using remote sensing methods, fieldwork, and spatial modeling, the investigators will seek answers to three core sets of questions: (1) What role do spatial processes play in determining woody cover dynamics at neighborhood scales? (2) Are these spatial processes resource- or disturbance-driven, and do they shift across climate gradients? (3) Do woody cover changes exhibit gradual or abrupt transitions (regime shifts) over time, and how are these dynamics related to fine-scale spatial structure and resource and disturbance gradients? Project findings will lead to a better understanding of the impacts that widespread increases in woody cover are having on habitat structure for wildlife, ecosystem function, and economic activity.