18,000 years of grassland evolution in the summer rainfall region of South Africa: evidence from Mahwaqa Mountain, KwaZulu-Natal
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- Neumann, F.H., Botha, G.A. & Scott, L. Veget Hist Archaeobot (2014) 23: 665. doi:10.1007/s00334-014-0445-3
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A palynological and sedimentological record from the Mahwaqa Mountain in KwaZulu-Natal, South Africa, provides evidence of the vegetation dynamics in this part of the Grassland Biome during the last c. 18,000 years. The wetland is located at 1,850 m on an isolated outlier of the Ukhahlamba–Drakensberg Mountain range on an ecotone along a climatic gradient. The vegetation responded to humidity and temperature changes during the late Pleistocene and Holocene. The period c. 18,000–13,500 cal. bp is characterized by high Ericaceae and Restionaceae percentages and decreasing values of charred particles, indicating cool conditions. Around 13,500–8,500 cal. bp, Ericaceae were gradually replaced by Poaceae, signaling climate warming. Growing environmental wetness during the same time period is inferred from Phragmites-type and Cliffortia pollen percentages. Since c. 8,500 cal. bp, Cliffortia, Restionaceae, and Phragmites-type percentages have maintained low levels. Ericaceae were almost completely replaced by grasses and Asteraceae by c. 7,500 cal. bp. All indications are that warm and fluctuating moisture conditions followed until 4,600 cal. bp but they became driest between c. 4,600 and 3,500 cal. bp, when high Asteraceae, Pentzia-type and Scabiosa percentages were prominent. From c. 3,500–800 cal. bp, the increase of sedges, Aponogeton and grass pollen (including Phragmites-type) at the expense of Asteraceae pollen suggests the return of slightly more humid conditions. Since c. 1,000 cal. bp an increase of water demanding Podocarpus and Cliffortia occurred. Pine pollen indicates the recent introduction of alien plants in the 19th and 20th centuries.