Late Quaternary soil genesis and vegetation history on the northern slopes of Mt. Kilimanjaro, East Africa

摘要

This study presents numerical dating and geochemical results obtained for a soil transect on the northern slopes of Mt. Kilimanjaro, East Africa. Accordingly, the investigated soils in the montane forest zone comprise Late Quaternary palaeosol-sequences, which are characterised by inverted weathering profiles. This can be explained through the aeolian accumulation of unweathered volcanic dust that is provided by katabatic winds from uncovered periglacial hillsides since at least 28 ka cal. BP. Several proxies (C/N, δ~(13)C, δ~(15)N and alkane biomarkers) provide evidence for vegetation changes during the Late Quaternary. Strikingly, an expansion of savannah or alpine C4 grasses as on nearby Mt. Kenya cannot be confirmed. However, C3 grasses expanded remarkably at 2600 m a.s.l. during the last glacial maximum and montane forest communities replaced the ericaceous/grassy communities during the Early Holocene.