Late Quaternary paleoenvironmental changes in tropical eastern Africa revealed by multi–proxy records from the Cherangani Hills, Kenya

Abstract

There is paucity in the proxy records available for the reconstruction of vegetation and climate histories of tropical eastern Africa, especially north of the equator. Here, we present a new paleoenvironmental record based on a 3.5-m sediment core from the Kapkanyar mire, Cherangani Hills, Kenya. Using analyses of pollen, microscopic charcoal, and loss-on-ignition data, we examine the vegetation and climate history of tropical eastern Africa over the past ∼23 Kyrs. Our findings show that high levels of dry montane forest vegetation and high frequencies of Poaceae and Chenopodiaceae/Amaranthaceae (Cheno/Am) pollen types dominate the LGM period (∼23.5–18 Kyrs). The last deglaciation (∼18–12 Kyrs) is marked by a decrease in Afromontane vegetation such as Ulmaceae, Combretaceae, and Podocarpus and resurgence in Cheno/Am pollen with a minimal representation of Olea pollen. The presence of Combretaceae pollen alongside increased percentages of Cheno/Am pollen indicates that cold and dry climate likely prevailed during the last deglaciation period. The record shows that the eastern African region was generally wet over most of the Holocene, albeit with increased frequency of drought episodes. The first imprints of anthropogenic activities in the record appear between ∼4 and 3.5 Kyrs.