Apart from Acocks (1988) there are no published descriptions of the vegetation of the greater Tanqua and Doring River drainage basin (Bayer et al. 1993). A botanical and physical description of the Tankwa- Karoo National Park (TKRNP) which occurs in Veldtype 31b (Acocks 1988) is provided. The three dominant geological formations, older glacigenic deposits of the Dwyka Group, followed by the succession of siliciclas- tic sediments of the Permian Ecca Group, with flat dolerite sills and dykes, underlie eight distinct plant communities. The plant communities can be divided into large open plains dominated by Galenia africana and Tripteris sp. in the erosion rills, Malephora luteola and Augea capensis common in the low lying areas and Zygophyllum microcarpum, Brownanthus ciliatus and Galenia crystallina common on the more shaly concave plains and low shale hills. Slightly elevated rocky areas are dominated by Ruschia cf. robusta, Ruschia spinosa communities, while crusts of stemless mesembs such as Rhinephyllum macra denium, Hereroa fimbriata and Cheiridopsis acuminata are found on the desert paved areas. Annual Asteraceae covers all the denuded and sparsely vegetated areas after good winter rains while annual mesembs colonise on the more sodic sites. A total of 259 plant species were collected sporadically over a period of eight years, this includes 65 succulents and seven species endemic to the Tanqua Karoo and immediate adjacent area of the Roggeveld Mountain Range and Sutherland. Four Tanqua Karoo endemic species were found in the park

A checklist of 864 plant taxa representing 355 genera and 93 families is given for the Karoo National Park. A total of 121 species are endemic to the Nama-Karoo, with Asteraceae the most common with 33 taxa. followed by Mesembryanthemaceae with 26 taxa. Phytochorological affinities indicate that 19.8% of the species are from the Nama- Karoo Biome only, another 19.8% are distributed over two biomes, and 41% of the species have a widespread distribution. The Karoo National Park conserves 30% of the recognized endemics of the Nama-Karoo Biome.

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