36. Dry Clay Highveld Grassland

Synonyms:

Dry Cymbopogon-Themeda Veld (A50), Pan Turf Veld (A51); Panicum coloratum Eragrostis curvula Grassland.

Statistics:

2 517 km²; ± 67% transformed; 0.00% conserved.

Locality & Physical Geography:

This grassland type covers the vast bottomland situations and "pan veld" in the Wesselsbron area and the northwestern Free State. Altitude ranges from 1 500 to 1 600 m.

Climate:

The summer rainfall averages 600 mm per year. Temperatures vary between extremes of -8°C and 39°C, with an average of 17°C.

Geology & Soil:

Dry, clayey, duplex soils (Sterkspruit, Swartland, Estcourt, Valsrivier and Kroonstad soil forms) are derived from

Ecca Group sandstone, mudstone and shale, with occasional dolerite sills.

Vegetation:

Grass species constantly present are White Buffalograss Panicum coloratum, Weeping Lovegrass Eragrostis curvula, Fan Lovegrass E. plana, Setaria nigrirostris and Themeda triandra, the latter often being dominant, but replaced by the two Eragrostis species when overgrazed. An indicator of the clay soil is Three-awn Rolling Grass Aristida bipartita, which becomes prominent in severely degraded areas. A prominent feature of a large part of this vegetation type is the presence of species with Karoo affinity, such as the dwarf shrubs Bitterkaroo Pentzia globosa, Bloublommetjie Felicia muricata, Ghombos F. filifolia and Lycium cinereum, the grasses Eragrostis obtusa, Saltpan Grass Sporobolus ludwigii and Large Carrotseed Grass Tragus racemosus, and the geophyte Yellow Snakehead Bulbine narcissifolia.

Key Environmental Parameters:

Dry clay soils, coupled with low rainfall in the western Free State, limit the distribution of this vegetation type.

Economic Uses:

Because of the droughty clay soils, this vegetation type is not normally ploughed, but is often heavily grazed by cattle and sheep.

Conservation Status:

No official conservation areas occur within this type. This grassland is often severely overgrazed. Karoo species

are often present on the dry clay soils - this is not interpreted as Karoo encroachment, but rather occupation of suitable habitat by Karoo elements.

Key References:

Kooij (1990), Kooij et al. (1990b).

Authors:

George Bredenkamp & Noel van Rooyen.