Etude écologique pour la gestion des mangroves à Madagascar : comparaison d'une mangrove littorale et d'estuaire à l'aide de la télédétection

Like tropical rain forests, mangrove woodlands do not remain unaffected by a continuous surface loss, neither in Madagascar nor in other parts of the world. Mangroves contain a great richness. They support different economic activities, especially traditional subsistence fishery, but also a market-oriented extraction of timber and fuel wood, as well as the installation of modern shrimp farms. In Madagascar, the activities of a multi-purpose mangrove wood market are threatening the sensitive mangrove ecosystems. Without an appropriate management, this involves the risk of its disappearance. Natural resources linked with the mangroves are a source of conflicts of interests between people promoting conservation or exploitation advantages. Both study areas, Mariarano and Boanamary on the north-western coast of Madagascar, present different aspects. They were studied and compared in order to understand their ecology, as well as the use and exploitation of mangrove wood – aiming at an ecologically and socio-economically sustainable management. For that purpose, the present work used remote sensing techniques, biological inventories, standardized questionnaires, and socio-economical analyses. The results were integrated in a Geographical Information System. Synthetic thematic maps based on satellite detection analyses show the studied mangrove formations in their present-day distribution as well as the extend of exploitation by man. Starting from these results, a planning concept was elaborated for the site of Mariarano, as a basis for a better protection and/ or a sustainable use of the mangroves.