STATE AND VEGETATION ECOLOGY OF PEAT SWAMP FORESTS IN MAPUTALAND, SOUTH AFRICA

摘要

Tropical peatland swamp forests (PSF) on the southeast coast of Africa (in Maputaland) are one of the most unique and rarest wetland types in southern Africa. Subsistence and semi-commercial farming on these peatlands impact negatively on the long-time survival of these rare eco-systems. Especially, clearing and burning for subsistence farming (esp. banana commercial plantations) is widespread and increasing. In 2003 various remnants of PSF were identified in the Kosi Bay area using satellite data. For vegetation studies 65 plots were laid out with different degrees of disturbance and degradation. Within each plot the following data were collected: species abundance and dominance, vegetation structure, hydrology, peat stratigraphy and human impact parameters. Pristine forests are relatively homogenous and species-poor, but with unique communities adapted to the particular site conditions. Selected tree harvesting and small scale gardening increases the species richness, albeit mainly by weeds and other disturbance indicators. Extensive drainage on large-scale plantations alters the site severely concerning both the vegetation change and site hydrology. In spite of being heavily affected by tree felling and the associated change in plant cover, the sites seem to have a certain degree of regeneration potential. This makes the succession back to near-natural stands possible, as long as the hydrology remains untouched and residual forests are able to provide diaspores for re-colonization. However, plantations with effective drainage seem to loose this capacity quickly causing the restoration measures of such sites to be intricate or even impossible henceforth.