39. Moist Cool Highveld Grassland

Synonyms:

Cymbopogon-Themeda Veld (A48); Themeda triandra-Eragrostis curvula Grassland.

Statistics:

48 959 km²; ± 72% transformed; 0.29% conserved.

Locality & Physical Geography.

This grassland is widespread, covering the central-eastern part of the highveld in the Free State, as well as the southern and eastern parts of Gauteng. Altitude varies from 1 400 to 1 600 m.

Climate:

Rainfall varies from 600 to 700 mm per year, occurring in summer. Temperatures vary from -11°C to 38°C, with an average of 17°C.

Geology & Soil.

Deep, red (Hutton) and yellow (Clovelly) soils, mostly on Karoo Sequence sediments but also on shale (Witwatersrand Supergroup), andesitic lava (Ventersdorp Supergroup) and some other substrates, predominate.

Vegetation:

In pristine condition Redgrass Themeda triandra dominates entirely, and few other species occur, particularly dicotyledonous forbs. Other grasses often encountered include: Broom Needlegrass Triraphis andropogonoides, Sawtooth Lovegrass Eragrostis superba, Velvet Signalgrass Brachiaria serrata, Elionurus muticus, Heteropogon contortus, Cymbopogon plurinodis and Setaria spacelata. Forbs include: Fishbean Tephrosia semiglabra, Wild Petunia lpomoea obscura, Brown Saffronbush Sutera atropurpurea, Deverra burchellii, Helichrysum rugulosum, H. caespititium, H. dregeanum, Crabbea acaulis, Hermannia depressa and Rhynchosia totta. When overgrazed, Weeping Lovegrass Eragrostis curvula replaces Redgrass Themeda triandra and becomes dominant. When in poor condition, other elements invade, including: karroid shrubs such as Bitterkaroo Pentzia globosa, Bankruptbush Stoebe vulgaris, Small Bietou Osteospermum scariosum and Walafrida densiflora; woody dwarf shrubs such as Dwarf Buffalothorn Ziziphus zeyheriana and Elephant's Root Elephantorrhiza elephantine; pioneer grass species such as Tassel Bristlegrass Aristida congesta, Couchgrass Cynodon dactylon, Eragrostis obtusa, Aristida canescens, Microchloa caffra and Tragus berteronianus; and forbs such as Chamaesyce prostrata, Bladderweed Hibiscus trionum and Rattlebush Blepharis integrifolia.

Key Environmental Parameters:

Grazing is important, but overgrazing converts this grassland to a Karoo type.

Economic Uses:

These soils are excellent for agronomy, and extensive areas are cultivated for maize and other crops. In its natural state it is intensively grazed by cattle and sheep.

Conservation Status:

Very poor. Cultivation has lead to the ploughing up of most of this vegetation type. The remnant patches of natural vegetation are intensively grazed and are consequently often degraded. The presence of Karoo elements in degraded sites is often seen as signs of Karoo encroachment into the Grassland Biome. The Bronkhorstspruitdam, Vaal Dam, Willem Pretorius, Rustfontein Dam and Koppies Dam Nature Reserves are the principal conservation areas, but comprise a very small area of this grassland type.

Key References:

Bredenkamp et al. (1989), Kooij et al. (1992), Fuls et al. (1993), Eckhardt et al. (1993b), Coetzee et al. (1994).

Authors:

George Bredenkamp & Noel van Rooyen.