The role of soil factors and leaf protein in the utilization of mopane plants by elephants in northern Botswana.

BACKGROUND: Mopane (Colophospermum mopane) plants form monotypic woodlands that cover extensive areas in northern Botswana. Mopane is also a principal food item in the diet of elephants. Obtrusive damage to mopane plants as a result of elephant feeding may alter the structure of mopane woodlands. Some mopane woodland areas in northern Botswana are subjected to heavy elephant utilization rates whereas other mopane areas are less affected. However, the underlying reason for the concentrated elephant utilization is unknown. RESULTS: Ten mopane plots were subjected to sampling of soil properties that included structure, pH, nitrogen, phosphorus, potassium contents and protein contents. Elevated nitrogen and phosphorus contents in soils correlated with high protein levels in mopane leaves. Protein levels in leaves of mopane plants differed significantly between sites. However, multivariate analyses of environmental parameters and plots suggested that on a regional scale, there was no difference in the extent of elephant damage to mopane plants due to differential protein levels in leaves or any of the underlying soi factors that were examined. CONCLUSIONS: From management perspective, this pattern mitigates the likelihood that an even more prolific elephant population will alter mopane woodland habitats irreversibly.