Late Quaternary ecotone change between sub-alpine and montane forest zone on the leeward northern slope of Mt. Kilimanjaro

QuestionsHow did the montane forest of the leeward northern slopes on Mt. Kilimanjaro respond to climate fluctuation during the late Quaternary? LocationMt. Kilimanjaro, Tanzania. MethodsPollen, phytolith and macro-charcoal analyses from a palaeosol. ResultsPalaeoecological analyses indicate that vegetation was mainly characterized by Ericaceae with Poaceae dominated by cold-adapted C-3 highland grasses during the pre-LGM and the LGM. From the last deglaciation onwards, the previous assemblage was progressively replaced by Podocarpus forest associated with Clematis and later the expansion of ferns, then Araliaceae, Hagenia abyssinica, Ilex mitis and Olea started in the early Holocene. ConclusionVegetation dynamics reveal that open sub-alpine vegetation associated with some components of afro-alpine grassland was located at a lower elevation than today, related to cold and dry conditions during the Late Glacial. In contrast to Mt. Kenya, our results show an absence of C-4 grass expansion on the northern slope of Mt. Kilimanjaro during the LGM. From the last deglaciation to the early Holocene, under temperature and precipitation increase, the vegetation zones moved upward, as indicated by the development of upper montane forest at the expense of the sub-alpine vegetation. Although we confirm the altitudinal movements of vegetation zones generally observed from the Late Glacial to the Holocene in East African mountains, our results also reveal the importance of local environmental conditions in mountain vegetation response.