The role of abandoned pastoral settlements in the dynamics of African large herbivore communities

A number of studies have begun to show the large impact that pastoralism has on African savanna ecosystems. Here we look at the impact of abandoned settlements on the distribution of the large ungulates of Amboseli, Kenya. Monthly dung counts show that all 9 species studied are attracted by settlements for up to a century after abandonment. Densities increased in the first two decades of vegetation succession, when plant biomass is the highest, then declines steadily to background levels as plant biomass. The pattern of herbivore use varied among species in the course of succession, with grazers dominant in early successional stages and browsers later stages, when shrubs and trees began to replace grasses. The densities of both grazers and browsers correlated positively with herbaceous and woody biomass respectively. We conclude that the additional biomass and higher quality forage produced by heavy dung deposits in livestock settlements are a major factor governing the distribution and movement of large herbivore in the savannas. The abandonment of seasonal migrations and construction of permanent settlements under way in African savannas is likely to restrict wildlife movements and reduce habitat patchiness and species richness of large ungulates.