A Holocene pollen record for the Kalahari Desert of Botswana from a U-series dated speleothem

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Abstract
A 61 cm core through a speleothem column in Drotsky's Cave, Botswana, has yielded a U-series dated pollen record of Holocene vegetation changes in the Kalahari Desert. Between c.10000-7000BP, the site was surrounded by an arid grassland with dry-adapted trees and shrubs such as Acacia and Commiphora. An increase in pollen of Combretaceae and Cyperaceae, and the appearance of pollen of such mesic savanna plants as Grewia between c. 7000—6000 BP, may indicate the onset of slightly wetter conditions. Combretaceae and other mesic pollen types increase between c. 6000-3000 BP, but the late Holocene record appears variable, with the period c. 5000-4000 BP being somewhat dryer than the millennia before and after. It would appear that Kalahari vegetation has changed less during the Holocene than many other African environments previously investigated. Despite the limitations imposed by pollen analysis of cave sites, the record from Drotsky's Cave shows good agreement with regional trends derived from other studies. The use of U-series dated pollen spectra derived from speleothems holds potential for expanding the geographic scope of palynological studies to areas lacking suitable lakes and bogs, and for extending the dated pollen record back an order of magnitude beyond the 14C timescale.

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