Two of the problems facing conservation in South Africa are limited resources and land reform initiatives. These problems, among others, make it necessary to prioritise. Prioritisation initiatives may be based on species distribution data or aggregate categories such as land classes. A combination of the two approaches may be advisable (Reyers et al. 2006). Reyers et al. (2006) used a GIS package and imagery from the National Landcover database (mostly captured 1994—1995) to prioritise the vegetation types identified in Low & Rebelo (1996). The land-cover classes were split into natural, degraded and transformed categories. The degraded category represented areas with lower vegetation cover while the transformed category represented areas with nearly complete to complete change in the structure and species composition of the vegetation. Information on protected areas was also considered (Reyers et al. 2006).
In order of priority, the top ten vegetation types identified by Reyers et al. (2006) were West Coast Renosterveld (Vegetation Type No. 62, Low & Rebelo 1996), Sand Plain Fynbos (Vegetation Type No. 68, Low & Rebelo 1996), Dry clay highveld grassland (Vegetation Type No. 36, Low & Rebelo 1996), South and South-west Coast Renosterveld (Vegetation Type No. 63, Low & Rebelo 1996), Short Mistbelt Grassland (Vegetation Type No. 47, Low & Rebelo 1996), Coastal Bushveld-grassland (Vegetation Type No. 23, Low & Rebelo 1996), Moist Cold Highveld Grassland (Vegetation Type No. 40, Low & Rebelo 1996), Sour Lowveld Bushveld (Vegetation Type No. 21, Low & Rebelo 1996), Afro Mountain Grassland (Vegetation Type No. 45, Low & Rebelo 1996) and Coast-hinterland Bushveld (Vegetation Type No. 24, Low & Rebelo 1996).
Reyers et al. (2006) do not appear to have considered invasive alien species among their threats – probably because identifying areas invaded by alien species is not likely to be efficiently done from satellite imagery or aerial photography and the costs (both financial and time) of extensive fieldwork are prohibitive. It is possible that heavily invaded sites would be included in the transformed land-cover category but this is not explicitly stated. This is possibly a limitation of the method and suggests that the calculated percentages of affected area are conservative.
The imagery used by Reyers et al. (2006) came from 1994-1995. Development is progressing rapidly in South Africa, particularly around urban areas. This is visible on the Cape Flats, e.g. on both sides of the Stellenbosch arterial road near Kuilsriver. Of the top ten conservation priority vegetation types, the expansion of the Cape Town metropolitan area is threatening both Sand Plain Fynbos and West Coast Renosterveld – the two vegetation types with the highest conservation priority. It is likely that the percentages of affected area calculated by Reyers et al. (2006) were already outdated by the time the article was published.
It is critical that formal conservation areas be designated to protect the vegetation types threatened by the expansion of Cape Town.
Low, A.B. & Rebelo, A.G. (1996) Vegetation of South Africa, Lesotho and Swaziland, Department of Environmental Affairs and Tourism, Pretoria. 0-621-17316-9 ISBN
Reyers, B., Fairbanks, D.H.K., Van Jaarsveld, A.S. & Thompson, M. (2006) Priority areas for the conservation of South African vegetation: a coarse-filter approach. Diversity and Distributions 7: 79—95.