Holocene vegetation history and palaeoenvironments at Klaarfontein Springs, Western Cape, South Africa

Several sediment cores around the coastal lake of Verlorenvlei, Western Cape, have thus far revealed important details of the development of this semi-arid winter-rainfall environment during the late Quaternary. Complex interplay between climate change, sea-level fluctuation and human activities have characterized the Verlorenvlei record and suggests that these environments have been subject to high degrees of disturbance over time. However, due to the discontinuous nature of the sedimentary record, the Holocene record has remained fragmentary. Investigation of a 6 m vibracore sequence at Klaarfontein (32 degrees 25'26S; 18 degrees 29'40E), an artesian spring site some 18 km inland of Eland's Bay, facilitates a more complete Holocene palaeoenvironmental reconstruction. Pollen concentrations in 37 spectra distributed through the 6 m core vary with organic content, but at all depths are sufficient to facilitate interpretation of vegetation history and reveal a high degree of dynamism in the local and regional environments. The lower sediments are characterized by elements strongly indicative of more xeric conditions and the catchment appears to have been dominated by drought-resisting woody shrubs. Local vegetation in the mid-Holocene is consistent with the occurrence of two sealevel transgressions resulting in each case in the development of a salt marsh at the site. The uppermost pollen spectra are all relatively modern (post 200 BP). Grass pollen declines from 1900 BP, possibly as a result of the occupation of the area by pastoralists, although climate change cannot be ruled out. A decline in pollen diversity towards the surface is associated with a further reduction in grass pollen and an increase in the proportion of succulents, hence offering support for the hypothesis of significant colonial and post-colonial disturbance of the vegetation. The evaluation of the. pollen sequence at Klaarfontein supports previous palaeoenvironmental reconstructions and at once reveals new insights regarding the complex Holocene limnology, hydrology and geomorphology of the Verlorenvlei system.