Plant communities and species richness of the Agrostis lachnantha–Eragrostis plana Wetlands of northern KwaZulu-Natal

Abstract

The wetlands described in this article include rivers, streams, vlei areas and pans occurring within the grasslands of northern KwaZulu-Natal. The vegetation of many of the wetlands, in particular high-lying vlei areas, is in danger of being irreversibly changed due to desiccation of the areas caused by the encroachment of exotic plantations into the high-lying grasslands, The objective of this study was to classify and describe the Agrostis lachnantha-Eragrostis plana major vegetation type associated with the wetlands. The TWINSPAN classification and subsequent refinement by Braun–Blanquet procedures resulted in the identification of 16 plant communities (also referred to as vegetation units), which were then related to environmental factors using the ordination algorithm DECORANA. Five distinct groups were distinguished, the distribution of which was primarily explained by axis 1. Species richness was calculated for each plant community from the phyiosociological data. In addition to this parameter, species rarity and naturalness of communities were also considered in an attempt to estimate the conservation value of specific sites. Although being relatively species poor, the vlei areas and pans are of particular conservation importance due to the restricted occurrence of certain species and the high degree of naturalness. However, no rare species were encountered.