Swartland Granite Renosterveld

Description

Distribution: Western Cape Province: Discrete areas in the Swartland: largest patch centred on Darling from Ratelberg in the north to Dassenberg near Mamre and Pella; several centred on Malmesbury from Darmstadt in the north to the lower slopes of the Perdeberg (and small patches to the west towards Atlantis); east of Wellington from Micha to Valencia, lower surroundings of Paarl Mountain; Joostenberg, Muldersvlei, Bottelaryberg, Papegaaiberg (Stellenbosch West), to Firgrove and northern Somerset West. Altitude 50–350 m. 6.8% of this vegetation type occurs within the City and 93.2% outside the City. Lower rates of transformation occurred nationally (75%) than inside City borders (86%).

Vegetation & Landscape Features: Moderate foot slopes and undulating plains supporting a mosaic of grasslands/herblands and medium dense, microphyllous shrublands dominated by renosterbos. Groups of small trees and tall shrubs are associated with heuweltjies and rock outcrops.

Geology & Soils: Coarse sandy to loamy soils of a variety of forms ranging from Glenrosa and Mispah, to prismacutanic and pedocutanic diagnostic horizons to red-yellow apedal soils all derived from Cape Granite. The soils can contain a considerable volume of moisture in winter and spring.

Climate: MAP 360–790 mm (mean: 520 mm), peaking from May to August. Mists common in winter. This is the wettest renosterveld unit. Mean daily maximum and minimum temperatures 27.7°C and 6.7°C for February and July, respectively. Frost incidence about 3 days per year.

Endemic Taxa: Low Shrubs: Agathosma hispida, A. latipetala, Aspalathus glabrata, A. rycroftii. Succulent Shrubs: Antimima menniei, Erepsia hallii, Lampranthus citrinus, L. scaber, Phyllobolus suffruticosus, Ruschia klipbergensis. Herbs: Arctopus dregei, Oncosiphon glabratum. Geophytic Herbs: Babiana pygmaea, B. regia, B. rubrocyanea, Geissorhiza darlingensis, G. eurystigma, G. malmesburiensis, G. mathewsii, G. radians, Haemanthus pumilio, Ixia aurea, I. curta, Lachenalia purpureo-caerulea, Moraea amissa, Oxalis stictocheila, Watsonia humilis.

Conservation: This is a critically endangered vegetation unit of which almost 80% has already been transformed due to prime quality of the land for agriculture (vineyards, olive orchards, pastures) and also by urban sprawl. Hence the conservation target of 26% remains unattainable. Only very small portions (0.5%) enjoy statutory protection in the Paarl Mountain Nature Reserve and Pella Research Site, and also (2%) in the Paardenberg and Tienie Versveld Flower Reserve near Darling. Alien grasses are particularly pervasive, the most important being Lolium multiflorum, Avena fatua and Bromus diandrus. Alien woody species include Acacia saligna, Pinus pinaster as well as various species of Eucalyptus.

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