Invertebrates on isolated peaks in the uKhahlamba-Drakensberg Park World Heritage Site, South Africa

Abstract

A survey to document and describe the alpine flora and various focal faunal taxa on six isolated inselberg-like peaks (total area of 31.9 ha), all 3000 m or higher, located in the uKhahlamba-Drakensberg Park World Heritage Site, South Africa, was undertaken in early summer in 2005. Study of the fauna of these peaks should be informative because the impacts of controllable anthropogenic threats on the invertebrate communities on them should be minimal or absent in comparison with those on the main massif. A total of 341 invertebrate individuals representing 61 species were recorded from the focal taxa (Oligochaeta, Gastropoda and certain groups of Insecta, i.e. focal taxa within the Blattoidea, Dermaptera, Orthoptera, Hemiptera, Diptera, Lepidoptera, Coleoptera and Hymenoptera). The 61 species recorded consisted of two species from the Oligochaeta, one species from the Gastropoda and 58 species from the Insecta. Eleven species (one from the Oligochaeta, ten from the Insecta) are endemic and 11 species (one from the Oligochaeta, ten from the Insecta) are probably endemic to the Drakensberg Alpine Centre, constituting 36.1% of the total species recorded. The results suggest that the Drakensberg Alpine Centre (DAC), as for plants, is a centre of endemism for invertebrates. Cluster analysis showed that the species composition of the two northern peaks, Sentinel and Eastern Buttress, clustered together, separate from a cluster formed by the Outer Horn, Inner Horn and Dragon’s Back and from the cluster formed by the southernmost peak, Cathkin. Non-metric multi-dimensional scaling results indicated that distance from the Sentinel, the most northerly peak sampled, and mean minimum temperature for July had the strongest correlations with the species data, reflecting change over a straight-line distance of nearly 60 km in a south-easterly direction.Conservation implications: Only a small proportion (ca. 5.5%) of the DAC is conserved, the majority of which lies in the uKhahlamba-Drakensberg Park World Heritage Site. Conservation of more of the DAC, including more of its latitudinal extent, is required to adequately conserve its unique plant and invertebrate communities.