Maley Jean. (1996). The African rain forest : main characteristics of changes in vegetation and climate from the Upper Cretaceous to the Quaternary. In :
Alexander I.J. (ed.), Swaine M.D. (ed.), Watling R. (ed.). Essays on the ecology of the Guinea-Congo rain forest. Proceedings of the Royal Society of Edinburgh.Section B, 104, p. 31-73.
Titre du document
The African rain forest : main characteristics of changes in vegetation and climate from the Upper Cretaceous to the Quaternary
Année de publication
1996
Type de document
Article
Auteurs
Maley Jean
In
Alexander I.J. (ed.), Swaine M.D. (ed.), Watling R. (ed.) Essays on the ecology of the Guinea-Congo rain forest
Source
Proceedings of the Royal Society of Edinburgh.Section B, 1996,
104, p. 31-73
This chapter sets out to give a historical overview of the African rain forest from its origins, towards the end of the Cretaceous period. The areas around the Gulf of Guinea, in particular from Ivory Coast to Nigeria and especially Cameroon, Gabon and Congo, appear to have been already occupied at this time by wet tropical forest formations mainly composed of Angiosperms which were then becoming established. In the course of the Tertiary period the combined effect of the equator being situated further north than now and the development of the Antarctic ice cap favoured the development of wet tropical conditions over a large part of North Africa which in turn led to the extension of tropical forest to various sites on the shores of the Tethys Sea. There were probably at this time common taxa and similar vegetation patterns stretching from the Gulf of Guinea to the Tethys Sea. Towards the end of the Tertiary, the equator reached its present position and the northern hemisphere ice caps appeared, and these phenomena resulted in the disappearance of the forest formations spread across the north of Africa, and the concentration of these formations near the equatorial zone around the Gulf of Guinea and in the Congo-Zaïre basin. From 800 000 years ago onwards the marked glacial variations at middle and high latitudes in both hemispheres, with a periodicity of about 100 000 years determined by the orbital variations of the earth around the sun, lowered temperatures in equatorial areas and brought arid climates at times of maximum glacial extension. The most arid periods resulted in the fragmentation of the forest cover, and the forest biotopes and their biodiversity were preserved in a series of refugia. The lowering of temperatures also resulted in the extension of montane flora to low altitudes, with migration of montane flora and fauna between main mountain ranges... (D'après résumé d'auteur)
Plan de classement
Géologie du quaternaire [064GEOQUA]
;
Formations végétales [082VEGET02]
