Limited impact of elephants on trees and shrubs in semi-arid thicket vegetation in southern Africa.

Abstract

When wide ranging, herbivorous species such as African elephants (Loxodonta africana) are confined and their population densities increase, the vegetation may be negatively affected. Any changes to vegetation structure and complexity may then result in a series of ecological cascades on other plant and animal species that rely on the vegetation for survival. We assessed the composition and structure of the woody and succulent plants within the locally endemic Albany Thicket Biome at five protected areas (reserves) with elephants in the Eastern Cape province, South Africa in 2006 and 2016. We show that when elephant populations in this region are actively managed, wholesale negative impacts on woody thicket plant physiognomy are not observed. In fact, the only statistically detectable change over time, presumably due to elephants, was the toppling of larger, single-stemmed trees. We believe that because the Albany Thicket Biome evolved in the presence of large, top-down browsers such as elephants, the generally negative effects that have been observed of elephants on vegetation in savanna systems are not evident. However, the reserves with elephants in the Eastern Cape are all relatively small (< 400 km2) and fenced which prevents elephant dispersal. Thus, continued monitoring of elephant browsing effects is crucial for the future conservation of this unique biome.