Selective disturbance by elephants (Loxodonta africana) on eight tree species in a West African savannah

Abstract

AbstractAfrican elephants (Loxodonta africana) are ecosystem engineers in African savannahs, but their role in the modifications of the populations of trees by means of their browsing activities has been poorly studied so far in West Africa. We studied the disturbance of elephants to eight selected species of trees in the Nazinga Game Ranch (Burkina Faso), in 54 transects at the end of dry season 2008. We fitted simple models describing the number of dead individuals for each tree species in relation to their initial population density, and in relation to dung‐pile density, in the assumption that there should be a positive relationship between elephant density and dung‐pile density. Generalized Linear Model analyses and regression analyses showed that the more dense the woodland cover, the least the percentage of damaged plants by elephants. For each plant species, the initial density and density of elephant dung‐piles explained a high proportion of the variance in the density of dead individuals. Stochastic models, generated by a purposely created simple computer program written in GW‐BASIC programming language, predicted changes in tree and shrub abundance under different assumptions about elephant numbers. The models suggested that elephant browsing may cause considerable change in the selected plant populations, especially with regard to such species as Acacia gourmaensis, Vitellaria paradoxa and Maytenus senegalensis. These changes may possibly increase the meat harvest from controlled hunting activities, thus improving the income for surrounding communities.