Robertson Karoo

Robertson Karoo - Southern Africa : To document the biodiversity within this centre of endemism of the Succulent Karoo. The Robertson Karoo is situated between the Langeberg and Riviersonderend Mountains from Worcester to Swellendam. It is situated in the rain shadow of these ranges, bl

To document the biodiversity within this centre of endemism of the Succulent Karoo.

The Robertson Karoo is situated between the Langeberg and Riviersonderend Mountains from Worcester to Swellendam. It is situated in the rain shadow of these ranges, bleeding into Renosterveld to the east and Fynbos to the west. Within the region Renosterveld (Breede Shale Renosterveld) tends to occur on the more moister upper and southern slopes, with Succulent Karoo predominantly on the north slopes and flats. The mountains are Fynbos. In areas the heuweltjies in the Renosterveld have Succulent Karoo communities.

Most of the area comprises Bokkeveld shales, with Cape Supergroup Sandstone below (and to the south) and Witteberg Quartzites on the hill crests. The Worcester fault runs to the north and exposes Malmesbury shales with the Hex and Langeberg Mountains again being Cape Supergroup Sandstones. The displacement of the Worcester fault reaches 6000m in the area.
The landscape is generally low hills and flats with ridges and hills where the quartzites occur, bounded by the high sandstone mountain chains. Spectacular folding can be seen near Montagu, but in the basin the rocks tend to be rather unfolded striking to the south.
Rainfall is mostly frontal in winter, with summers hot and dry.

The Breede River runs the length of the Valley. Route 62 from Worcester to Robertson to Ashton to Montagu passes through the north. Additional towns include Bonnievale, McGregor and Swellendam.

Many endemic species occur in this Karroid centre of endemism. The Klein Karoo is the adjacent Succulent Karoo centre to the north of the Langeberg.

Nature reserves include Pat Busch, Vrolikheid and the Karoo National Botanical Garden.

References:
http://open.uct.ac.za/bitstream/handle/11427/8415/thesis_sci_1990_wood_jc.pdf?sequence=1

The Robertson Karoo as pastural area Joubert JGV
African Journal of Range and Forage Science 5. http://www.ajol.info/index.php/ajrfs/article/view/1234

Abstract
In the Robertson Karoo eight plant communities can he distinguished. Quantitative plant surveys were conducted in all the communities. Succulents form an important component of the vegetation. The plant communities are very stable after invasion by succulents which tend to remain dominant more or less permanently. A small percentage of the vegetation is eaten by stock. There is very little edible material in the summer, but more in the winter and spring. The veld is vulnerable to grazing from late autumn (May) until the end of spring (October) on account of leaf development and flower formation. The successful establishment artificially-sown, edible, Osteospermum sinuatum, raises great hopes, for radical improvement of the veld.

06 May 2016
Tony Rebelo