68. Sand Plain Fynbos

Synonyms:

Coastal Fynbos (A47); Phylica cephalantha Fynbos.

Statistics:

5 208 km²; ± 50% transformed; 1.05% conserved.

Locality & Physical Geography:

From the Olifants River Mouth to Muizenberg on the West Coast lowlands from 5 to 300 m. In the lower Berg River region extensive mosaics of Strandveld Succulent Karoo and Sand Plain Fynbos occur, apparently related to subtle physiographic changes in landscape which influence fire spread.

Climate:

Mediterranean with summer drought. Rainfall from 200 to 500 mm per year, mainly in winter.

Geology & Soil:

This is confined to the deep acid sands of the West Coast. Most of these sands are of Tertiary origin, being aeolian and podsolized, but some are derived from the Cape Granite Suite and Table Mountain Group sandstones. In some areas waterlogging may occur, with wetland and swamp communities, but usually the sands are well-drained.

Vegetation:

The vegetation is typical Asteraceous and Proteoid Fynbos and does not differ structurally from equivalent Mountain Fynbos types, although very few species are shared. Heaths (Ericaceae) are seldom dominant, but ericoid-leaved shrubs tend to dominate with the Reeds (Restionaceae) and Sugarbushes (Proteaceae). Sand Plain Fynbos is characterized by the presence of Ninepin Heath Erica mammosa, Starface Phylica cephalantha, Baboonface P. stipularis, and the restioids Thamnochortus obtusus and Sandveld Thatching Reed T. punctatus. In the south the incidence of grass is much higher than in the north, but most of these are alien Mediterranean grasses. Three centres of endemism occur within this vegetation type (Fig.1), each characterized by their own suite of proteaceous overstorey.

Key Environmental Parameters:

Sand Plain Fynbos is defined by the presence of deep, acid sands on the flats. It is confined to the West Coast, where the uniform conditions result in a relatively monotonous vegetation type - the variety of communities found in Mountain (64) and Limestone (67) Fynbos is not found.

Economic Uses:

In the south, urbanization is transforming this vegetation type. Elsewhere it is used for grazing, but the carrying capacity is low. Smallholdings are transforming the natural vegetation to poor pasture, mainly for horses.

Conservation Status:

Only the Riverlands Nature Reserve and a few small Natural Heritage Sites currently conserve Sand Plain Fynbos. The region comprises three major centres of endemism. Of these the southern-most centre is almost engulfed by the Cape (Town) Metropolitan Area. At least 84 Red Data Book Plant species occur in this vegetation type within the boundaries of the metropolis and are in danger of extinction. The vegetation is also heavily impacted by alien Acacia species, primarily Port Jackson A. saligna, but also Rooikrans A. cyclops. The area south of Dassenberg and from Malmesbury to Philadelphia is being subdivided into small-holdings despite their identification in the Jarman report as being of critical conservation importance. The proposed linkup of the Riverlands Nature Reserve with the Kalabaskraal, Groenrivier, Dassenberg and Pella sites, as suggested in the Jarman report, has not yet been implemented. The area between Milnerton and Malmesbury must rank as one of the world's hottest spots for the loss of plant biodiversity.

Key References:

Boucher (1981), Moll et al. (1984), Jarman (1986).

Author.

Tony Rebelo.