Dynamiques des paysages de la vallée du Yamé depuis 4000 ans. Contribution à la compréhension d'un géosystème soudano-sahélien. (Ounjougou, Pays dogon, Mali).

摘要

The main of objectives study of the landscape dynamic of the Yamé valley since 4000 years is to understand the genesis of landscapes and their changes since the societies are beginning to manage intensively the environment. Through this research, we contribute to the knowledge of African cultural landscapes taking into account anthropic and bioclimatic actions. The Yame Valley is located in the Sudano-Sahelian zone in central Mali. It is the main rivers of the Dogon Country. In order to respond to our problem, we choose for a thematic plan. In the first section, we present the framework and contexts of study. The second part consists of a chronostratigraphic presentation at high resolution. The third part is the analysis of fluvial system and hydro-sedimentary analyses thanks to (from grain-size distributions and micromorphology). The fourth part is a presentation of vegetation cover and their evolution (palynological, anthracological, carpological methods and analysis of signal fire). The fifth part is a synthesis of results, with a spatial and temporal interpretation of the valley Yame landscapes changes during four thousand years the past. This study reveals a progressive opening of landscapes associated with a change of appearance of vegetal species in relation with an aridification at the climate and the establishment agrosystems in the area. The vegetation has changed in the valley between different mosaics of savannas and woodlands which are gradually of Sudano-Sahelian character. Pyrophiles species are progressly more while farming emergence millet by the archaeobotanical data and seasonal anthropogenic fires. These analyses it is suggest landscapes scenarii that synthesize Dogon Country landscapes developments and the anthropic roles importance. Thus highlighted the growing the influence of societies in their environment during the past four millennia in West Africa leading to the buiding of cultural landscapes.