Challenges in resolving and protecting biodiversity in a developing city : the case of the Cato Ridge grasslands, Durban.

Abstract

The area of Cato Ridge has been identified as a key node for future industrial and commercial development within the eThekwini Municipal Area, with a Local Area Plan approved to guide it. However, it also includes large areas of natural vegetation, including some of the best remaining instances of grassland in the city. These grasslands have been mapped as Ngongoni Veld but parts on Natal Group sandstone have contrarily been mapped as KwaZulu-Natal Sandstone Sourveld by the eThekwini Municipality’s Environmental Planning and Climate Protection Department. KwaZulu-Natal Sandstone Sourveld is considered endangered and deserving of greater conservation attention. However, little information is available about either of these grassland types. This thesis is based on surveying of 236 plots each of 100 m2 situated in better quality grassland throughout Cato Ridge, focusing on the herbaceous component. Plots were surveyed widely in order to determine and compare species richness and composition on different geological substrates (mainly Dwyka Group tillite and Natal Group sandstone), and different aspects and slopes, including respective occurrence of endemic and biogeographically important species and Cape floristic elements. Dwyka Group tillite plots were found to contain higher species richness. Both these plots and those on Natal Group sandstone were found to contain endemics, biogeographically important and Cape floristic element species. These results are used to interpret the question whether grassland on different geological substrates is to be referred to as Ngongoni Veld or KwaZulu- Natal Sandstone Sourveld. I conclude that, contrary to what has often been suggested in the past, under natural conditions Ngongoni Veld is neither a species-poor grassland type, nor does it lack distinctive species and deserves greater conservation attention. All occurrences of all grassland in better condition are mapped and compared with the land uses set out in the Local Area Plan. From this it is apparent that the plan enables their significant reduction and degradation, and requires amendment if this is not to occur.