48. Coastal Grassland

Synonyms:

Eastern Province Thornveld (A7); Coastal Sour Grassveld, Coastal Mixed Grassveld.

Statistics:

2 709 km² ; area transformed unknown; 1.13% conserved.

Locality & Physical Geography:

Coastal Grassland extends along the Eastern Cape coastal region.

Climate:

Rainfall is generally high (above 1 000 mm per year), occurring mostly during summer. Temperatures vary between 8°C and 39°C, with an average of 21°C. Extreme conditions of wind and salt spray occur.

Geology & Soil:

The rocks weather to form a dystrophic, sandy clay loam with dark topsoils rich in organic matter. Owing to the high rainfall, these soils often show signs of gleying owing to the accumulation and persistence of water at the soil-rock interface. Elsewhere, the soils are of marine origin and are often shallow.

Vegetation:

Dominant grass species are Redgrass Themeda triandra, Hairy Tridentgrass Tristachya leucothrix, Broadleaf Bluestem Diheteropogon amplectens, Cymbopogon excavatus, lmperata cylindrica, Sporobolus nitens, Eragrostis plana, Hyparrhenia spp., Heteropogon contortus and Stenotaphrum secundatum. An abundance of herbaceous plants is commonly found, as are Fynbos patches throughout the region. Shrubs include Blombos Metalasia muricata, Gonnabos Passerina rigida, Dune Crowberry Rhus crenata, and Maytenus procumbens. A diversity of species and a wide range of grassland communities occur along the extensive coastline. Locally some endangered species become abundant and some unusual and unique communities, such as halophytic moist grasslands, are found locally in some areas.

Key Environmental Parameters:

Acocks mapped this grassland type as a Coastal Tropical Forest type - today it is a complex mosaic of forest, thicket and grassland. There are many shrubby species in these grasslands showing the successional trends to forest where deeper soils are found. However, the high number of grassland endemics suggests a long stable existence as a climax grassland community. This vegetation type is subjected to extreme conditions of wind and salt spray, and these may be the controlling factors in the maintenance of this short grassland along the coastal region. The depth of the water table plays a major role in determining the distribution of halophytic and swampy communities.

Economic Uses:

Coastal grasslands are important grazing lands.

Conservation Status:

This vegetation type is not conserved to any great extent. It is under threat from increasing pressure for coastal resort developments. The abundance of endangered species and the presence of unusual and unique communities suggest that they merit high conservation consideration. The area is presently seen as a very important centre of endemism, seriously impacted by forestry and agriculture.

Key References:

Lubke et al. (1 986, 1 988).

Authors:

Roy Lubke, George Bredenkamp, Ed Granger & Noel van Rooyen.