Abstract

The serpentinite outcrops of the Barberton Greenstone Belt are considered to be amongst the oldest in the world and have been exposed for over 50 million years. Of the 30 large outcrops in eastern Mpumalanga, South Africa, seven were selected for detailed comparison of species richness and diversity with those of surrounding non-serpentine vegetation. Various non-parametric species richness estimators were calculated to predict the species richness of each site and these indicated that four serpentine outcrops have higher and three have lower species richness than the surrounding non-serpentine areas. The Shannon, Simpson’s and Fisher’s alpha indices of diversity were calculated for each site on and off serpentine and compared. The diversity values calculated show similar patterns to those of the species richness estimates. Significant differences in species composition between floras on and off serpentine were estimated using Sørenson’s Index of similarity. The serpentine outcrops of the Barberton Greenstone Belt show relatively high diversity when compared to some other serpentine outcrops around the world.

Key words: Diversity indices, EstimateS, Modified-Whittaker plots, serpentine, species accumulation curves, species richness estimation.