Contributions to the ecology of Maputaland, southern Africa, with emphasis on Sand Forest

Abstract

The principal hypothesis of this thesis was that the Maputaland Centre of Plant Endemism [MC] is characterised by plant communities that match a particular set of environmental variables, and their rich biodiversity with endemic and rare taxa reflecting the geomorphological history of the region. Data assembled supports the hypothesis. Vegetation studies highlighted two plant communities, endemic to the MC as being an important component of the region’s biodiversity, namely Sand Forest and Woody Grassland. A broad approach to the floristic classification of vegetation was adopted for information on the floristics patterns and diversity of the endemic/rare plants and plant communities of the MC. A hierarchical classification, description and ecological interpretation of the plant communities of the Tembe Elephant Park, Sileza Nature Reserve and surrounding areas are presented. Much of the vegetation distribution can be ascribed to the level of the water table, vegetation dynamics and historic evolution of the geomorphology of the region. The hypothesis is presented that Sand Forest may have allelopathic effects on its environment. Data of exploratory germination trials are presented to test this hypothesis. Sand Forest soil inhibits the emergence of seedlings, the inhibiting effect decreasing progressively from Sand Forest through grassland to woodland. Sand Forest was defined as a community, and its possible dynamics are described. Ideas were formulated (albeit largely hypothetical) on the likely origin of this vegetation type. It is proposed that ancient Dune Forest is the precursor of Sand Forest, but that Sand Forest has subsequently become a separate functioning plant community on its own. Sand Forest appears to be a relictual vegetation type of which the historical factors responsible for it’s original establishment and expansion are currently no longer present in the region. The use of woody species by elephant in different vegetation types in Tembe Elephant Park was investigated. A classification of species into utilization categories was produced which enabled assessment of the importance of different species to elephants, and also of the potential impact of elephants on different tree species. Management implications are highlighted.