29. KARROID KALAHARI BUSHVELD

Synonym:

Kalahari Thornveld (A16).

Statistics:

18 643 km²; ± 55% transformed; 0.13% conserved.

Locality & Physical Geography:

Occurs on the flat, gravelly plains at an altitude of 1 000 m, north and north-west of Upington and in the Noenieput-Rietfontein area, north of the Orange River in the Northern Cape.

Climate:

The average annual rainfall is 175 mm, occurring mainly in summer. Temperatures vary between -8C and 42C, with an average of 20C.

Geology & Soil:

The substrate is characterised by sandy calcareous tufa which is sometimes covered with a layer of granitic gravel.

Vegetation:

The tree layer is almost non-existent and very sparsely scattered individuals of Camel Thorn Acacia erioloba and Shepherd's Tree Boscia albitrunca may be found in areas where an accumulation of sand has occurred. The shrub layer is moderately developed and individuals of Cauliflowerbush Salsola tuberculata, Thornkapok Eriocephalus spinescens, Threethorn Rhigozum trichotomum, Rosenia humilis, Aptosimum spinescens and Eriocephalus pubescens are commonly found. The grass layer is poorly developed, and grasses such as Small Bushman Grass Stipagrostis obtusa and Tall Bushman Grass S. ciliata are the dominant species. Grasses of less general occurrence are Eightday Grass Enneapogon desvauxii, Ring Windgrass Eragrostis annulata, Blue Windgrass E. porosa, E. homomalla, Tragus racemosus and Schmidtia kalihariensis.

Key Environmental Parameters:

These are low rainfall gravel plains influenced by the grazing of livestock.

Economic Uses:

Livestock farming of cattle, goats and sheep.

Conservation Status:

Very poorly conserved.

Key Reference:

Leistner (1967).

Authors:

Noel van Rooyen & George Bredenkamp.