THE IMPORTANCE OF HERBIVORE INTERACTIONS FOR THE DYNAMICS OF AFRICAN SAVANNA WOODLANDS - AN HYPOTHESIS

Current hypotheses to explain dynamic transitions between savanna gras slands and woodlands in Africa focus on grazing by elephant or the inf luence of fire. Using a simple mathematical model, this paper argues t hat interactions between small herbivores such as impala or buffalo an d large herbivores such as elephant or giraffe may provide a plausible alternative hypothesis. The interplay of competition and facilitation between these types of herbivores could explain transitions between g rassland and woodland and vice versa. A review of the literature is pr esented in support of this hypothesis.