Effects of elephants and goats on the Kaffrarian succulent thicket of the eastern Cape, South Africa

Kaffrarian succulent thicket is a dense, semi-succulent, thorny vegetation dominated by the tree-succuluent Portulacaria afra, which is rapidly being eliminated under current pastoral systems. The effect of defoliation by wild herbivores (mostly Loxodonta africana) was compared with that of domestic ungulates (mostly Capra hircus) from surveys inside and outside Addo Elephant National Park. Both elephants and goats reduced canopy cover and increased shrub density. Goats reduced the number of dominant shrub species per quadrat. Replacing elephants with goats resulted in a fundamental change in the shrub community to one dominated by small, unpalatable shrubs with a few scattered umbrella-shaped trees. Removing elephants and not replacing them with goats resulted in the sites becoming more dissimilar, possibly because the vegetation reacted to the unique climatic and edaphic potential of each site. Goats reduced the percentage frequency of P. afra by 40% and its density by 71% causing a 91% declinein the total area rooted by this plant. Kaffrarian succulent thicket (in particular P. afra) appears to be adapted to elephant utilization but not to utilization by small domestic ungulates stocked at equivalent biomass. -from Author