Use of an area-based survey technique to detect vegetation changes in Sour Bushveld

Abstract

Most strategies for monitoring vegetation change on reserves and game ranches are based on point methods. Area-based methods form the basis of initial floristic classifications from which vegetation maps are constructed. The question arises whether or not these area-based methods can be used for monitoring or not. This paper compares two area-based data sets from the same sites with an intervening period of five years. Data were collected on a Sour Bushveld game farm, in the Limpopo Province of South Africa. The structure of the woody vegetation, particularly in two communities reflected a plant successional progression over time. All six re-surveyed sites reflected an increase in plant species richness and this increase was most substantial in one community where the total number of plant species increased from 17 in 1996 to 34 in 2001 at one sampling site and from 26 in 1996 to 45 in 2001 at the other. This study has shown that change in species composition can be detected using area-based sampling techniques but that absolute measures, such as density, should be employed rather than estimates, especially with regard to plant cover.