Modifications de l'environnement dans les estuaires et mangroves de l'afrique de l'ouest: Influence des phenomenes naturels et impacts humains

Abstract

The West African mangroves, particularly those of the ‘southern rivers’, developed on typical Quaternary formations dating from ca. 6500 BP, present a remarkable adaptation to the ecological conditions of the area and to its constraints. These include variations in salinity, quantities of fresh water, soil and water acidity, and substrate composition and texture. The generally low topographic relief, and the presence of sandy beach sediments, provide additional controls on mangrove development. During recent years, however, changes have occurred in the mangroves as the result of (a) natural phenomena, in particular the importance and incidence of recent desertification (for example in the northern part of the Saloum of West Africa), and (b) anthropogenic factors, with the traditional multiple use of the mangroves as a preferred area for rice cultivation, salt and wood exploitation, and for the great agricultural management projects, designed to transform these mangroves and areas of exposed sediments into fertile lands.