Woody vegetation structure in conserved versus communal land in a biodiversity hotspot : a case study in Maputaland, South Africa

Abstract

This study evaluated the effects of humans and herbivores on woody vegetation structure in the woodlands and forests of Maputaland. The woody vegetation structure of plant communities at three sites within a similar environment but under different utilisation regimes since the early 1990s was evaluated by means of a stem diameter and tree height class analysis. The effects of human utilisation were evaluated on the land of the rural Manqakulane community; herbivore utilisation was evaluated in the Tembe Elephant Park; and because of the low levels of utilisation since 1992 the vegetation in the Tshanini Community Conservation Area was used as a benchmark for the comparisons. In both woodlands and sand forests, utilisation regime resulted in changes in stem diameter size class distributions, although the height structure remained unchanged. In communal land human-associated disturbance promoted the presence of small woody plants. In general, conserved land under animal utilisation, had the least small diameter woody plants, but most of the large trees, whereas in the absence of utilisation intermediate densities of small diameter woody plants were found but low densities of large trees. This study presents the first quantification of significant changes in the woody vegetation structure in Maputaland due to human utilisation, herbivore utilisation, or lack of utilisation. It also provides a timeframe within which land use can cause significant changes in vegetation structure.