The impacts of Cape porcupines on woody plant mortality

Abstract

In terrestrial ecosystems, the activities of semi-fossorial animals such as Cape porcupines have important landscape effects that may manifest in the dry season when the availability of above-ground forage becomes limiting. We investigated the effects of foraging activities of Cape porcupines on savanna landscapes. We measured the size (surface area and depth) of foraging holes of porcupines located at the base of trees in the dry season in two mesic savanna sites at Roodeplaat Farm and Bisley Valley Nature Reserve in South Africa. We also recorded plant and animal activities inside the foraging holes for 3 months. The depth of foraging holes beneath small trees (Vachellia nilotica) was greater than depths beneath old trees (V. robusta and D. rotundifolia). This resulted in the subsequent death of most (>50%) small impacted trees in the dry season at Bisley. The surface area of foraging holes for older trees was greater than that for small trees and even greater for old holes. This study showed that porcupines kill trees or expose them to secondary attacks. The physical impacts of semi-fossorial herbivores in savannas can be significant, with contributions to direct and indirect landscape transformation and restoration.