Influence of Grazing on the Composition of Themeda Triandra Grassland, East Africa

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Abstract
Four areas of Themeda triandra grassland were sampled in 1959 to determine the relative influence of grazing by wild and domestic herbivores and effects of different grazing intensities on percentage species composition. One area was Queen Elizabeth Park in Uganda, another was in the Mara Plains of southwestern Kenya, the 3rd was near Seronera Camp in the Serengeti Plains, and the 4th was the floor of the Ngorongoro Crater. The soils in each study area were sampled and analyzed for both physical and chemical characteristics. Differences in Themeda grassland composition were related more to grazing than to soil. The widespread species occurred in abundant and scarce quantities over a wide range of soil characteristics. While there is suggestion in the data that various animal species influence the grassland in different ways, the most striking correlations of vegetational changes were with intensity of grazing rather than kind of grazing animal. In other words, concentrations of wild animals result in overgrazing and deterioration of the grasslands just as does overgrazing by domestic animals. This conclusion is not new but it emphasizes again the need for proper management of all animals. Successional stages in the Themeda grassland resulting from overgrazing are climax tall grasses dominated by T. triandra; an intermediate stage of Cynodon, Pennisetum, and others; a short grass stage; and a weed stage. These stages usually exhibit an increasing proportion of bare soil, decreased plant height and less foliage cover. The weed stage is poor condition range vegetation but stipulation of range condition as excellent, good and fair for the other stages depends upon the management objectives. Different kinds of animals prefer plants in each of the successional stages so that excellent range for one may be poor for another.