Masters Degrees (Forest and Wood Science)

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Browsing Masters Degrees (Forest and Wood Science) by Subject "Acacia -- South Africa -- Atlantis"

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    The ecological effect of Acacia saligna in a sand plain fynbos ecosystem of the Western Cape, South Africa
    (Stellenbosch : Stellenbosch University, 2002-12) Van den Berckt, Tom; Boucher, C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science .
    ENGLISH ABSTRACT: The invasive Australian acacia, A. sa ligna, is widespread in the Western Cape, South Africa, and is widely used by local communities. Not surprisingly, the introduction of the biological control agent, the fungus Uromycladium tepperianum in 1987 was received with mixed emotions. In an effort to determine the socio-economical and ecological impact of the fungus, the Department of Water Affairs and Forestry has commissioned a study, of which this thesis forms part. For this thesis, a number of parameters, environmental as well as biological, were sampled, analyzed and compared with existing data from previous studies. The goal was to obtain a comprehensive estimation of the effect of A. saligna on a Sand Plain Fynbos community near Atlantis and to assess whether or not, the detrimental effect A. saligna has on plant biodiversity, has reached the stage where it has become irreversible. The floristic data confirmed results from earlier studies, that invasion of A. saligna in Fynbos communities induces a decline in plant diversity, especially in dense acacia thickets. This study mainly revealed structural changes rather than community shifts. The enrichment of the soil as noted by others authors was also confirmed for the study area. However, it was outside the scope of this study to determine the long-term effects of this enrichment on the Sand Plain Fynbos communities. Soil moisture content was sampled on three different occasions, in densely invaded and uninvaded study plots. The aim was to see if A. saligna had any influence on the availability of water in the upper soil. Contrary to expectations, moisture content under acacia stands was higher in spring and early summer in the top soil than in pristine fynbos. Pitfall traps were used to sample the arthropods that dwell the surface of the study area. For arthropods in general, the survey did not produce conclusive data, but spider species seem to be positively affected by the presence of A. saligna, probably due to the structural diversity they add to the fynbos. This study revealed that the full ecological impact of A. saligna on its environment is far from understood, mainly due to the richness and complexity of the fynbos communities and a lack of research about faunal aspect of the Fynbos ecosystem.