CRB: Elephant Browsing and Patch Dynamics in a Colophospermum mopane African Savanna

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In biomes1 ranging from subarctic taiga forests to tropical savannas and woodlands, selective browsing by mammals can alter the composition and diversity of vegetation and, as a result, the rate of nutrient cycling. The objective of this project is to gain an understanding of this process, because it is of critical importance to sound ecosystem management. The interaction between browsing mammals (specially elephant), vegetation, and nutrient cycling in the savanna-woodlands of the Zambezi River Region of Zimbabwe will be studied. This system was selected because 1) it is a classic example of the more general mammal-vegetation-nutrient cycling problem, 2) the interaction between the African elephant and its habitat is, in its own right, of major concern to international conservation, 3) the Zimbabwe Department of Parks and Wildlife is strongly supporting this project, and 4) The United States Agency for International Development (USAID) has funded the nutrient cycling portion of this study. Specifically, patterns of browsing in the Colophospermum mopane woodlands, one of Africa's major vegetation types and a critical habitat will be studied. Repetitive browsing by elephant is the major form of natural disturbance influencing patch dynamics in mopane scrub and woodland, because elephant repeatedly browse some patches of mopane in preference to others with the results that the vegetation of repetitively browsed patches is degraded. This proposal will test 3 alternative explanations of the rebrowsing of mopane by elephant 1) sodium enrichment of the soil in the vicinity of preferred patches, 2) nutrient (e.g. nitrogen) enrichment of the soil, or 3) proximity of browsed patches to traditional paths of travel to focal resources such as water or mineral licks.