Negative Impacts of Termite Mounds on the Vegetation in Mopane Savanna in Northwestern Namibia

Abstract

The purpose of this study is to clarify the impact of termite mounds on the vegetation of mopane (Colophospermum mopane) savanna in Northwestern Namibia. This area is a part of a mopane zone with a high distribution of termite mounds. Much previous research on termite mounds has been conducted in humid tropical areas. Such studies have found termite mounds to have high fertility and thus to be a key factor in vegetation dynamics. Few studies, however, have focused on the relationship between termite mounds and vegetation in arid or semi-arid areas, and the impact of the mounds on savanna vegetation remains unclear. In the area where I conducted research, almost all termite mounds were found together with trees. The composition of tree species on the mounds reflected the composition in the surrounding vegetation, but Combretum spp. dominated slightly more than other species. The rate of withered trees, especially Terminalia prunioides, was higher on the mounds than on the ground. Moreover, termite mounds were extracted as one of the parameters of tree withering from a statistical model analysis using a generalized linear model (GLM). As a result of this study, termite mounds appeared to act as negative factors in vegetation growth on or near the mounds. The mounds should, therefore, be taken into account as one of the factors that disturb vegetation dynamics in mopane savanna.