What factors influence the occurrence of Cubitermes pallidiceps in miombo woodlands in southwestern Burundi?

Abstract

In Africa, not only large number of termite species remain to be described, but also ecological studies on the termite fauna of the continent are scarce. For instance, the mechanisms underlying termite mounds distribution in ecosystems stay poorly known. The main goal of this study was to assess what determines the distribution of soil-feeding termites playing an important role in the recycling of organic matter. The case of Cubitermes pallidiceps (Sjöstedt) (Isoptera: Cubitermitinae) was taken as a model. In Rumonge Forest, a woodland miombo of 600 ha in southwestern Burundi, we collected soil samples and data on tree density and diameter in 18 sites, six of which were home to mounds of C. pallidiceps. Multiple logistic regressions were used to evaluate the influence of soil properties and elevation on the occurrence of C. pallidiceps. Spatial autocorrelation structure in the model residuals was corrected by the integration of selected spatial predictors generated with the Moran’s eigenvectors maps (MEM) method. C. pallidiceps was present in areas where the tree density was low, therefore with a more opened canopy, probably to avoid fires. Those areas would also provide it a favourable microclimate through direct solar radiation. It was absent in stony places such as hill tops, probably because of food limitation. Soil with high sand content and the highest measured clay content seemed to favour Cubitermes occurrence. Its distribution was also influenced by undetermined spatially structured variables, which could correspond to unmeasured environmental variables such as soil nutrient or toxic elements, or variables related to dispersal abilities or biotic interactions with other species. Our results suggested that soil termites would have evolved in miombo ecosystems to avoid areas with a high physiological and physical cost. Understanding ecological adaptation of soil termites in this stressful environment is important for restoration and management of their habitats.