A palynological investigation of uMgeni Vlei Nature Reserve (Kwa-Zulu Natal) - late Quaternary vegetation and climate fluctuations in eastern South Africa

Eweto, Kevwe
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The uMgeni Vlei Nature Reserve, an area located within the midlands of KwaZulu-Natal of South Africa, was investigated for palaeoenvironmental history and climatic change. Palynology, which is a popular technique to reconstruct southern African past environments, was utilized during this research, as it is directly a means of reconstructing vegetation histories which then can be used to infer changes in climate. A 300 cm sediment core, rich with organic content was obtained from the uMgeni Vlei wetland. Seven samples taken for radiocarbon dating indicated that the chronology is not reliable as the returned ages were not in chronological order and therefore indicates a great degree of disturbance to the sediment. What can be determined from the dating is that the sequence is of Holocene age as the oldest sediments at 141cm depth is dated to 10 680 cal yr BP. Pollen analysis reveals Poaceae, Asteraceae, Liliaceae and Phragmitesas the dominant plant taxa during the Holocene within the uMgeni Vlei record. CONISS analysis separates the sequence into three zones of statistically significant similarities. Environmental conditions deduced from the pollen spectrum of Zone 3 is characterised by warmer conditions, and pollen of Asteraceae, Anacardiaceae and Cerastium dominate the bottom depth at 254cm. Zone 2 was marked with increased moisture availability where pollen taxa of Cyperaceae, Liliaceae, Anthospermumand Phragmites flourished in relatively warm conditions. Increased moisture availability continued to be detected in Zone 1 as water-loving plants such as Podocarpus, Ascolepis and Aponogeton dominated the top of the sequence. The palaeoclimatic trend comparison of palaeoenvironmental records from Mahwaqua, Ntsikeni, Braamhoek and Clarens reveal a palaeoclimatic trend similar to the uMgeni vlei.
A dissertation submitted to the School of Geosciences, Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science (MSc), 2022