Vegetation of the Square Kilometre Array (SKA), South Africa: A baseline to measure local and global change

Abstract

Phytosociological studies provide plot-based vegetation data which can be used for numerous purposes. Recently, the potential of historical phytosociological plot data has been emphasised as a means to study vegetation change over time. Vegetation change occurs naturally but also as a result of land use and climate change. In order to quantify change, the current vegetation has to be compared with the vegetation that occurred historically at a site. The objectives of this study were to describe the vegetation on two properties (Losberg and Meysdam) purchased by the National Research Foundation on which the Square Kilometre Array (SKA) will be developed, and publish, in the scientific arena, the vegetation and landscape unit descriptions of these properties to promote awareness that baseline data exists before significant land use change occurred on the properties.One hundred and eighty Braun Blanquet surveys were conducted in units stratified using satellite images, topography, land type, geology and drainage information. The plot data were analysed using standard Braun Blanquet methodology. Ten plant communities and 2 sub-communities were identified. These plant communi-ties and sub-communities were used, together with landforms and associated environmental parameters, to produce five landscape units for decision making and management purposes.The data shows the past effect of disturbance. Historical overgrazing is speculated to have resulted in large patches denude of vegetation and the densification of the naturally occurring spinescent shrubs Rhigozum trichotomum and Lycium cinereum over large areas as in other parts of the Karoo. Significant soil erosion is evident. Soil conservation infrastructure erected in the past to combat further erosion, together with the highly disturbed vegetation and soils, has enabled the alien invasive tree species Prosopis glandulosa to proliferate in exceptionally large numbers, particularly on the flats and drainage areas. This highlights the importance of limiting disturbance to the natural vegetation and soils during the construction of SKA infrastructure. The study provides baseline vegetation data to inform the management of the proposed SKA protected area and for researchers working at this site. These data will also prove useful for ongoing monitoring efforts to detect the impact of local and global change on the vegetation of the Nama Karoo.