Thicket types:

Dune thicketValley ThicketXeric Succulent ThicketMesic Succulent Thicket Spekboom Succulent Thicket

7. MESIC SUCCULENT THICKET

Synonym:

Valley Bushveld (A23).

Mesic Succulent Thicket

Statistics:

1 931 km²; ± 51 % transformed; 5.33% conserved.

Locality & Physical Geography.

This is an exceptionally dense, impenetrable thicket occurring in the coastal areas

from the Sundays River Mouth to the Gamtoos Valley.

Climate:

Rainfall varies from 450 to 550 mm per year and occurs mainly in the winter or spring-autumn months. Temperatures range from 10 to 35°C, with a mean of 18°C. The thicket is found in drier rain shadow areas of the winter or spring/autumn rainfall region.

Geology & Soil.

Soils vary and include consolidated dune sands, as well as lime-rich, sandy clays derived from the Uitenhage Group. Densest thickets usually occur on deep, apedal, sandy loams to sandy-clay loams (Hutton and Clovelly forms) and this may be one of the factors responsible for the confined distribution of this vegetation type.

Vegetation:

The height of this dense, almost impenetrable, thicket is about 2.5 m and cover is about 90%, consisting mainly of spinescent shrub and woody creepers with many succulents. The diversity is high and it has a high proportion of endemics. Characteristic woody species include White Milkwood Sideroxylon inerme, Dune Kokotree Maytenus procumbens and Septemberbush Polygala myrtifolia, while succulent species such as Uitenhage Aloe Aloe africana, Bitter Aloe A. ferox, Noorsdoring Euphorbia ledienii and E. grandidens may be common.

Key Environmental Parameters:

Low rainfall and soil types may be controlling factors in the distribution of this vegetation type.

Economic Uses:

The dense nature of this thicket makes it very unsuitable for goat farming. It mainly occurs in conservation regions and it may be cleared for agriculture.

Conservation Status:

Along the coastal region Mesic Succulent Thicket is under throat from coastal resort developments and urban expansion. There are only small conserved areas along the Swartkops River. Succulent collectors are likely to exploit the many species, and there is a high proportion of threatened species in this thicket type.

Key References:

Cowling (1984), Everard (1987).

Author.

Roy Lubke.