The role of ancient human settlements in creating nutrient hotspots in a savanna ecosystem, central Zimbabwe.

Abstract

Ancient human settlements play an important role in creating heterogeneous African savanna ecosystems through forming nutrient hotspots with increased biodiversity and improved forage quality. However, plant community development and herbivore utilization of these sites after abandonment remain poorly understood. We compared plant and soil parameters in ancient human settlements with off-sites locations. In addition, we set camera traps in ancient settlements and surrounding vegetation to determine their use by herbivores. Grass basal cover, height, biomass and species diversity in ancient settlements had recovered to similar levels with the surrounding landscape. Ancient settlements had small trees (in terms of height and canopy volume), lower tree density and lower species diversity than the surrounding landscape. Soil phosphorus and calcium were higher in ancient settlements than surrounding landscape, while pH, nitrogen, potassium, magnesium and sodium were similar between the two sites. Impala and greater kudu camera sightings were higher in ancient settlements than surrounding vegetation, while warthogs showed no preferential foraging between ancient settlements and surrounding vegetation. We conclude that ancient settlements created functional heterogeneity through altering the structure of savanna vegetation influencing foraging patterns of herbivores such as impala.