9726642 Young This project will support a long-term, large-scale factorial experiment on the effects of native and domestic herbivores on each other and on the land they share in East Africa. Eighteen 4-ha plots have already been established that exclude six replicated combinations of (1) cattle, (2) wild large mammals, and (3) mega-herbivores (elephants and giraffes). This is the first controlled exclusion experiment that factors out the separate and combined effects of livestock and large wild herbivores, providing a unique opportunity to answer a series of basic and applied questions about the ecology of semi-arid ecosystems. This research is being conducted at Mpala Research Centre in north central Kenya. It is home to a largely intact fauna that is characteristic of East African savanna woodlands, including elephants, two species of zebras, cape buffaloes, elands, gazelles, giraffes, hertebeests, oryxes, lions, leopards, cheetahs, and many other species of large and small mammals. This proposal will document compensatory responses of the vegetation and of non-excluded herbivores, underlying vegetation changes associated with exclusion, the mode and rate of encroachment by woody plants, and the maintenance of the nutrient-rich glades that appear to me major organizing features of this landscape mosaic. This research will elucidate several fundamental issues in ecology, including the maintenance of resource hot-spots by endogenous ecosystem processes in a landscape mosaic.
