Climate of the Past www.clim-past.net 1814-9324 1814-9332 5 4 2009 10.5194/cp-5-647-2009 http://www.clim-past.net/5/647/2009/ http://www.clim-past.net/5/647/2009/cp-5-647-2009.html http://www.clim-past.net/5/647/2009/cp-5-647-2009.pdf 647 659 2009-10-26 Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change? A. Ngomanda ngomanda@yahoo.fr A. Chepstow-Lusty M. Makaya C. Favier P. Schevin J. Maley M. Fontugne R. Oslisly D. Jolly Institut de Recherche en Ecologie Tropicale, IRET/CENAREST, BP. 13354, Libreville, Gabon Institut des Sciences de l'Evolution de Montpellier, UMR 5554, Université de Montpellier II, Place Eugène Bataillon, cc 61, 34095 Montpellier Cedex 5, France Université des Sciences et Techniques de Masuku, Département de Géologie, BP. 901, Franceville, Gabon Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA/CNRS 1572, Domaine du CNRS, 91198 Gif sur Yvette cedex, France IRD – Cameroun, BP. 1857, Yaoundé, Cameroun formerly at: Institut des Sciences de l'Evolution de Montpellier, UMR 5554, Université de Montpellier II, Place Eugène Bataillon, cc 61, 34095 Montpellier Cedex 5, France deceased Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, <i>Elaeis guineensis</i>, and the shrub, <i>Alchornea cordifolia</i> (Euphorbiaceae). 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