Pollen records of past climate changes in West Africa since the last glacial maximum
by
A.M. Lézine and C. Agwu
URA 1761-CNNRS/UMPC, Jussieu, BP 106 F-75252 Paris Cedex 5 (France)
Coauthors: APD Members:, M.D. Bengo, P. Brenac, J.-P. Cazet, L. Dupont, Th. Edorh, H. Elenga, H. Hooghiemstra, S. Jahns, A. Le Thomas, J. Maley, U. Salzmann, A. Sowunmi, I. Reynaud-Farrera, J. Ritchie, E. Schulz, A. Vincens, M. Waller

Environmental reconstruction since the Last Glacial Maximum in North-West Tropical Africa has been severely limited by the incomplete record, owing primarily to major discontinuities in lacustrine sediments preserved in a predominantly arid climate. Only two long, detailed pollen sequences, from deep crater lakes document the whole deglacial and Holocene history of the humid equatorial forest (Maley and Livingstone,1983; Maley and Brenac, 1998). The other continental sites from Equatorial West Africa (Elenga et al., 1992; 1994; 1996 ; Reynaud-Farrera et al., 1996; Vincens et al., 1994; 1999, 2000) , the Sahelian Zone of Nigeria (Salzmann and Waller, 1998; Edmunds et al., 1999), Chad (Maley, 1981) and Senegal (Lézine, 1987, 1988), the Sahara (Lézine, Schulz, 1987; Schulz et al., 1990; Ritchie 1987, 1994; Ritchie et al., 1985; Ritchie and Haynes, 1987), closely dependant on local hydrogeological conditions (Lézine and Casanova, 1989) provide detailed " windows " on short, humid periods of the Holocene. Comparison with marine sedimentary sequences that provide continuous, well dated records on longer time series allows to reconstruct changes in both past atmospheric pattern over West Africa (Agwu and Beug, 1982; Hooghiemsta, 1989; Hooghiemstra et al., 1986; 1992; Lézine, 1991; Lézine et al., 1991; 1994; Lézine and Le Thomas, 1995), vegetation distribution (Sowunmi, 1981; Dupont, 1999; 2000; Dupont and Weinelt, 1996; Hooghiemstra et al., 1992; Jahns, 1996) and hydrology (Lézine, 1991; Cazet, 2001) at sub-continental as well as local scales. The African Pollen database present here the review of pollen data from Western Africa and nearby Eastern Atlantic with the aim to understand the vegetation response to past climatic and hydrological changes at different time scale during the last climatic cycle. Interpretations of pollen diagrams are based on numerous studies on both modern pollen deposition from the Equatorial evergreen and semi-deciduous forests to the south (Brenac, 1988; Elenga, 1992; Farrera, 1995) to the Sudanian, Sahelian and Saharan driest ecosystems to the north (Lézine and Edorh, 1991, Lézine and Hooghiemstra, 1990; Maley, 1972, 1981; Ritchie, 1987) (Fig.1), and land-sea correlations (Lézine and Hooghiemstra, 1990; Bengo 1996). Pollen based reconstruction of vegetation changes in Central and West African (Continental Data)

Date received: June 25, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cahr-41.