Vulnerability, irreplaceability and reserve selection for the elephant-impacted flora of the Addo National Elephant Park, Eastern Cape, South Africa

Abstract

The Addo Elephant National Park (AENP) is the only existing national park situated in succulent thicket. This unique veld type is endemic to the Eastern Cape, and forms an important centre of endemism for small succulents and geophytes which comprise the subdominant component of the vegetation. It is regarded as the most threatened vegetation type in the Eastern Cape, as much of it has been severely degraded by farming activities and its rate of regeneration is very low. Thus the AENP represents an important sanctuary for certain species. However, large herbivores, particularly elephants, pose a further threat to the vegetation, and areas from which elephants have been excluded in the park (botanical reserves) have been shown to be more speciesrich than the surrounding vegetation. Most elephant-impact studies have focussed on the large shrub component of the vegetation, and only preliminary studies have been done in AENP to date. As the elephant population continues to grow, there is pressure to utilise the botanical reserves to increase the amount of available grazing. It is thus important that the botanical reserve system be highly effective and efficient in terms of area. Existing botanical reserves were established ad hoc and are therefore not necessarily optimal in this regard. An iterative reserve-selection algorithm was used to maximise plant species conservation in the most efficient area.