The physical environment and major plant communities of the Karoo National Park, South Africa

Abstract

The major plant communities of the Karoo National Park are described using the methods of the Zurich-Montpellier school of phytosociology, to assist with the formulation of a management strategy for the park. The vegetation physiognomy consists of Montane Karoo grassy shrublands. Karoo grassy dwarf shrublands. Karoo succulent dwarf shrublands and riparian thicket. Steep elevation and precipitation gradients within the study area have a direct impact on gradients in the vegetation. High elevation (1 800 m), and relatively high rainfall (406 mm) montane grasslands occupy communities dominated by grasses (Merxmuellera disticha, Themeda triandra) and woody species (Diospyros austro-africana, Elytropappus rhinocerotis, Euryops annae, Passerina montana). The increasing aridity away from the escarpment edge in a northerly direction is steep, and Montane Karoo dwarf shrublands replace these mesic communities. Species such as Eriocephalus ericoides, Rosenia oppositifolia and Pteronia tricephala dominate. At lower elevation (800 m) the precipitation is very low (175 mm) and uncertain (coefficient of variation of 78 ). The substrata influence the vegetation, with the sandy substrata of the drainage lines supporting more woody taxa (Acacia karroo, Lycium cinereum) and grasses (Hyparrhenia hirta, Stipagrostis namaquensis, Cenchrus ciliaris). Moving away from the mesic environment of the riparian zone, rapid desiccation occurs and the most xeric communities are encountered, dominated by Stipagrostis obtusa, S. ciliata and Pent-da incana. This document provides descriptions of the general communities and their associated landscape, lithology and soils.