Thicket types:

Dune thicketValley ThicketXeric Succulent ThicketMesic Succulent Thicket Spekboom Succulent Thicket

4. DUNE THICKET

Dune Thicket

Synonyms:

Dune Forest (Al d), Strandveld (A34a); Xeric Kaffrarian Thicket; Dune Fynbos-Kaffrarian Thicket Mosaic.

Statistics:

3 666 km² ; ± 25% transformed; 14.49% conserved.

Locality & Physical Geography:

A dense thicket which occurs along fairly mesic sites along dunes and at low altitudes (less than 30 m) along the coastal strip from the Western Cape into KwaZulu-Natal. It may be confined to a narrow strip above the beach. In the southern Eastern Cape and Western Cape it forms a mosaic of Dune Fynbos and thicket patches.

Climate:

Rainfall ranges from 900 to 1 500 mm per year, mostly in the summer in the north, but in spring and autumn in the south, and in winter in the Western Cape.

Geology & Soil:

These thickets occur mostly on deep regic dune sands and often there is little humus build-up and soils develop to the Fernwood form. Dune Thicket is also occasionally found on granites, shales and sandstones adjacent to coastal dunes.

Vegetation:

The flora has affinities with that of Tongoland-Pondoland and many Cape elements may by found in the early seral stages, which is often classified as Dune Fynbos. Dominant trees and shrubs include: Coast Red Milkwood Mimusops caffra, Coast Silver Oak Brachylaena discolor, Natal Wild Banana Strelitzia nicolai, Sideroxylon inerme, Maytenus heterophylla, Rhus crenata, Maytenus procumbens, Passerina rigida, Carissa bispinosa, Scutia myrtina and Chrysanthemoides monilifera. Lianas and climbers are common, but there is generally little herbaceous cover in the dense thicket. Dune Thicket is subject to blow-outs and successional stages from dune pioneers through to dune scrub are evident all along the coast.

Key Environmental Parameters:

Dune Thicket occurs on young sands which are protected from fires, often by their dune topography. Where fires are more frequent in the winter-rainfall region, Dune Fynbos tends to occur as the early seral stage. As soils become more leached, Fynbos communities tend to dominate fire-exposed areas in the Western Cape. In dune areas inland of the sea, and especially on the inland-facing slopes, Coastal Forest replaces Dune Thicket.

Economic Uses:

Woody elements may be used for firewood. Along the south coast of the Western Cape White Milkwood Sideroxylon inerme stands have been ploughed up for crops because of their humus-rich fertile soils.

Conservation Status:

Dune Thicket is fairly well-conserved along many parts of the coastline, with good stands in the West Coast National Park and the De Hoop Nature Reserve. The greatest threat is the removal of thicket for the development of coastal resorts and the invasion of thicket by woody aliens in the Eastern and Western Cape. The White Milkwood S. inerme is a protected tree under the Forestry Act and may not be damaged.

Key References:

Cowling (1984), Everard (1987).

Author.

Roy Lubke.