The late holocene vegetation history of Lake Farm, South Eastern Cape Province, South Africa
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University of Cape Town
Palynological analysis of organic sediments from a freshwater lake near Port Elizabeth (34Â°S,25Â°30'E) has provided a high- resolution vegetation history of the area for the last 2200 years. Detailed identification and counting of the fossil pollen resulted in the generation of a pollen diagram. Changing frequencies in fossil pollen over time are represented, and inferences are made regarding environmental conditions which influenced the vegetation. A detailed narrative of vegetation history in response to environmental change is presented, and this is compared to results from related studies. The significance of the Lake Farm study site has been noted in terms of its location as a 'zone of convergence' for a variety of vegetation types. Results of fossil pollen analysis indicate that environmental conditions prior to 1 500BP were drier than at present. Forest and fynbos vegetation were not well-represented in the pollen spectrum at this time, and it is suggested that they were not favoured by these conditions. Environmental conditions ameliorated after 1500BP, becoming more mesic, which favoured the proliferation of both forest and fynbos vegetation types. At present xeric and grassland elements are declining, while shrubs increase, indicating an enhanced human-induced disturbance regime. It is suggested that the partial decline in forest elements at present 1s most likely attributable to human-induced disturbance of the environment. The introduction of exotic trees has been noted (approx. 280BP) and is seen to have coincided with the influx of european settlers to the region. Principal Components Analysis has revealed that the vegetation distribution in the area has been most heavily influenced by human activity and moisture availability. The necessarily subjective interpretation of the statistical results, however, casts some doubt on the validity of the conclusions drawn. The validity of the conclusions drawn from this study becomes apparent not only in terms of what is learned about the history of forests, but also the form any future management should take.
Bibliography: p. 155-175.
Adams, T. 1994. The late holocene vegetation history of Lake Farm, South Eastern Cape Province, South Africa. University of Cape Town.