Alexandre A., Meunier J.D., Lézine A.M., Vincens A., Schwartz Dominique. (1997). Phytoliths : indicators of grassland dynamics during the late Holocene in intertropical Africa. Palaeogeography, Palaeoclimatology, Palaeoecology, 136 (1-4), p. 213-229. ISSN 0031-0182.
Titre du document
Phytoliths : indicators of grassland dynamics during the late Holocene in intertropical Africa
Année de publication
1997
Auteurs
Alexandre A., Meunier J.D., Lézine A.M., Vincens A., Schwartz Dominique
Source
Palaeogeography, Palaeoclimatology, Palaeoecology, 1997,
136 (1-4), p. 213-229 ISSN 0031-0182
The reconstruction of African tropical grassland history during the late Holocene can be carried out using phytolith analysis. Fossil phytolith assemblages from Lake Guiers, in the Sahelian region of Senegal, and from Lake Sinnda, in the Guineo-Congolian region of Congo were investigated. The results are interpreted on the basis of modern phytolith assemblages from the same regions and compared to pollen data previously obtained. Tall or short grass associations are discriminated by their phytolith index Iph(%) = saddle/(cross+dumbel+saddle), while the density of shrubs and trees is indicated by relative proportions of the dicotyledon phytoliths. The phytolith data emphasize that, in the Guineo-Congolian region around Lake Sinnda, the driest phase of the late Holocene occurred between 4000 and 1200 yr B.P., commencing with the opening of the dense forest and its replacement by a short grass savanna. From ca. 1000 yr B.P., wetter climatic conditions developed, as represented by the setting up of a tall grass savanna woodland. The modern shrub and tall grass savanna was developed ca. 700 yr B.P. In the Sahelian region around Lake Guiers, the driest phase occurred after about 2000 yr B.P. and has not been followed by moister conditions. A tall grass savanna woodland was gradually replaced by a shrub and short grass savanna which still occurs. A short period of development of swampy vegetation, which can be related to a lake level change, interrupted the semi-arid adaptation of the vegetation, between about 2000 yr B.P. and the present. (Résumé d'auteur)
Plan de classement
Géologie du quaternaire [064GEOQUA]
Descripteurs
QUATERNAIRE ; HOLOCENE ; PALEOENVIRONNEMENT ; MILIEU LACUSTRE ; PALEOBOTANIQUE ; PALYNOLOGIE ; PHYTOLITHE
Description Géographique
SENEGAL ; ZONE SAHELIENNE ; CONGO
Localisation
Fonds IRD [F B010014984] ;
Bondy
Identifiant IRD
fdi:010014984
