Dynamics of some forests in Kwa Zulu-Natal, South Africa, based on ordinations and size-class distributions

Abstract

Indigenous forest in Kwa Zulu-Natal has been fairly well described, however, very little has been published on its dynamics. There is, to our knowledge, nothing published on disturbances regimes, dendrology and life histories of constituent species. In order to assess the conservation status, management and sustainability of these forests the authors have developed a dynamic framework by synthesizing information collected in many randomly located 400-m2 sample plots in a range of forest types. The authors have made lucid that ordinations between understorey and overstorey data form these plots would indicate the grain of a forest. Fine-grained forests would be indicated by close proximity, in ordination space, of understorey and overstoery. Similarly the authors urge that a predominance of canopy species with negative exponential size-class distributions should typify the more fine-grained forests. The analysis made by the authors suggests dynamics spectrum like; from fine-grained upland forests with in situ recruitment from advanced regeneration for most canopy species, to coarse-grained lowland forests where canopy species have flat size-class distributions and spatially variable recruitment. These results are discussed with a view to the conservation of the different types.