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The last climate cycle
Vegetation change recorded by a transect of marine pollen records along the African west coast.
Work of many people over years, first at the University of Göttingen and now at the University of Bremen, has delivered a unique body of data about the vegetation history of Africa. Important contributions were made by Chiori Agwu, Hans-Juergen Beug, Henry Hooghiemstra, Susanne Jahns, Fabienne Marret, Ning Shi, and others.
We palynologically studied a transect of marine cores situated between 30°N and 25°S along the west African coast covering the past 150 000 years (150 ka) extracting information on the vegetation history of the adjacent African continent. We found important changes for all main vegetation zones.
- During glacial Stages 6 (until 130 ka) and 1 (since 12 ka), the Mediterranean forest strongly declined or disappeared completely from the southwest Mediterranean area and was replaced by an open steppe-like vegetation.
- The Saharan-Sahelian boundary migrated and far south as 15°N - during Stage 6 (until 130 ka), during Stage 2 (between 28 and 12 ka), and during Substage 5d (115-105 ka) - and as far north as 23°N (during Substage 5e, 130-115 ka).
- The rain forest was widespread during Stages 1 and 5, but strongly reduced during Stages 4 and 3 (between 74 and 28 ka) and especially during Stages 6 and 2 (until 130 ka and between 28 -12 ka) when open, grass-rich vegetation prevailed. Glacial rain forest refuges probably remained in the southwest of the Guinean mountains and along the eastern coast of the Gulf of Guinea.
- Miombo woodland expanded during Stage 5 (130-74 ka) and contracted strongly during the glacial periods.
- Afromontane Podocarpus forests had their largest expansion during Substages 5d and 5b. Podocarpus did no longer occur in the Guinean mountains after Stage 5.
- During the glacial Stages 6 and 2, elements of the Cape vegetation migrated northwards along the Great Escarpment.
Vegetation change in equatorial West Africa: Time-slices for the last 150ka
Dupont, L.M., Jahns, S., Marret, F., Shi, N.
Palaeogeography, Palaeoclimatology, Palaeoecology, 155 (2000) 95-122
SE trade wind variations during the last 135 ka: evidence from pollen spectra in eastern South Atlantic sediments
Shi, N., Schneider, R., Beug, H.-J. & Dupont, L.M.
Earth and Planetary Science Letters 187 (2001) 311-321
Vegetation zones in NW Africa during the Brunhes chron reconstructed from marine palynological data
Dupont, L.M.
Quaternary Science Reviews 12 (1993) 189-202
Dupont, L.M. (1999) Pollen and spores in marine sediments from the east Atlantic. A view from the ocean into the African continent. In: Fischer, G. & Wefer, G. (eds.), Proxies in Paleoceanography, examples from the South Atlantic. Springer, Berlin: 523-546.
