Swartland Silcrete Renosterveld

Description

Distribution: Western Cape Province: A highly fragmented type, scattered in form of small patches throughout the Swartland from near Firgrove and Kuils River in the south to Eendekuil to Piketberg in the north. Mostly embedded within Swartland Shale Renosterveld followed by Swartland Granite Renosterveld. The largest patch is at Oupas between Moorreesburg and Mamre. Altitude 40–220 m. 14.8% of this vegetation type occurs within the City and 85.2% outside the City. However transformation rates are higher nationally (92%) than inside City borders (81%).

Vegetation & Landscape Features: Moderately undulating lowlands, often on elevated areas. An open, low, cupressoid- and small-leaved, low to moderately tall shrubland with many succulents, dominated by renosterbos.

Geology & Soils: Remnants of silcrete layers over Malmesbury Group Shale and Cape Granite. Soils with prismacutanic and/or pedocutanic diagnostic horizons or plinthic catena are dominant.

Climate: MAP 250–650 mm (mean: 425 mm), peaking from May to August. Mists common in winter. Mean daily maximum and minimum temperatures 28.7°C and 6.8°C for February and July, respectively. Frost incidence 3 or 4 days per year.

Endemic Taxa: Low Shrub: Marasmodes oligocephala. Succulent Shrubs: Lampranthus dilutus, Ruschia serrulata. Geophytic Herb: Babiana longiflora.

Conservation: Critically endangered and the conservation target of 26% remains unattainable due to total transformation of 90% (mainly turned into agricultural land). Small patches (about 1%) are statutorily conserved in the Pella Research Site, and additionally in Paardenberg and Elandsberg. Remaining patches undergo transformation by overgrazing, fire protection, and spraying with herbicides and insecticides. Alien Acacia saligna, A. mearnsii, Prosopis and Eucalyptus are also problem in places.

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