How homogeneous is West Coast Renosterveld? Implications for con­servation

Abstract

In this paper, we test two published assumptions about West Coast Renosterveld, a highly fragmented vegetation type in South Africa. The first is that it is a homogeneous vegetation type. The second is that small fragments are subsets (in terms of species) of the larger fragments. We used three sets of data. Species lists showed that more than 44 % of the species identified at 16 sites were unique to that site. Examining the dominant and rare species occurring at subsites within large fragments showed that, on average three-quarters, and never less than half, of the species were confined to one subsite. Analyses of rare and endangered plant species lists showed that the average distance separating patches of the same species was almost 30 km. Only 36.4 % of the rare or endangered species localities coincided with a major (> 25 ha) fragment. Our first conclusion was that many endemic species are constrained by micro- or meso-habitat demands that are not immediately obvious to the observer, and hence the vegetation should not be considered locally homogeneous. Our second conclusion was that the smaller fragments (< 25 ha) are of importance for the conservation of West Coast Renosterveld plant species.