37. Dry Sandy Highveld Grassland

Synonyms:

Western Bankenveld (A61), Dry Cymbopogon-Themeda Veld (A50); Dry Cold Temperate Grassland, Eragrostis obtusa-Eragrostis lehmanniana Dry Grassland, Stipagrostis uniplumis-Fingerhuthia africana Grassland.

Statistics:

56 924 km²; ± 65% transformed; 0.28% conserved.

Locality & Physical Geography.

Found on the plains in the dry western parts of the Free State and south-eastern parts of North-West Province, and from sandy areas west of Wesselsbron, extending south-eastwards towards Bloemfontein. The landscape is flat to gently undulating, at an altitude of 1 370 to 1 460 m.

Climate:

The summer rainfall is erratic with an average of 450 mm per year. Temperatures vary between -11°C and 41°C, with an average of 18°C.

Geology & Soil:

Deep, red to yellow, apedal, aeolian sand, often covering limestone.

Vegetation:

This is a grassland with a few Sweet Thorn Acacia karroo trees occurring only occasionally along water courses. Diagnostic grasses include the grasses Lehmann's Lovegrass Eragrostis lehmanniana, E. obtusa, Small Buffalograss Panicum coloratum and Stipagrostis uniplumis, and the karroid dwarf shrub, Bitterkaroo Pentzia globosa. Other prominent grass species include Redgrass Themeda triandra, Weeping Lovegrass Eragrostis curvula, Hairy Lovegrass E. trichophora, Anthephora pubescens, Aristida congesta, Digitaria eriantha and Cynodon dactylon. A large variety of dicotyledonous forbs are also present, including Chamaecrista mimosoides, Poison Apple Solanum panduriforme, Tummy Bitterroot Dicoma anomala, Helichrysum callicomum, H. cerastioides, Kyphocarpa angustifolia, Leucas capensis, Gnidia capitata, Blepharis angusta, Anthospermum hispidulum and Acalypha angustata. West of Bloemfontein, affinity to Karoo vegetation can be seen in plant communities dominated by dwarf shrubs, including Fringed Karee Rhus ciliata, Anchorkaroo Pentzia incana, Bitterbush Chrysocoma ciliata, Helichrysum pentzioides, Salsola kali, Felicia muricata, Walafrida densiflora, W saxatilis and Nenax microphylla.

Key Environmental Parameters:

This grassland merges with the bordering Kalahari Thornveld to the west. Acocks mapped the area west of Wesselsbron as Kalahari Thornveld, probably due to the sandy soils of Kalahari origin, but floristically and structurally the vegetation today is a Dry Grassland. The presence of Karoo elements in the west probably represent outliers of Karoo vegetation, but this should not necessarily be considered as encroachment.

Economic Uses:

The erratic summer rainfall makes this a high risk area for agronomy. Crops, such as maize, have replaced the grazing for which this area is better suited.

Conservation Status:

Very poor. Although an excellent cattle and sheep farming area, many areas have been ploughed for the cultivation of maize. Today natural vegetation is only represented by small remnants which are often degraded as a result of overgrazing. Officially conserved areas include the Barberspan, Vaalspa, S.A. Lombaard and Erfenis Dam Nature Reserves.

Key References:

Morris (1 976), Kooij et al. (1990a), Malan (1992), Fuls (1993), Bezuidenhout et al. (1994b).

Authors:

George Bredenkamp & Noel van Rooyen.