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Dynamique récente d'évolution des mangroves de la région de Toliara (Madagascar)

Ricardo Andriatsiaronandroy Onjanamboara 1
1 LETG - Nantes - Littoral, Environnement, Télédétection, Géomatique
CNRS - Centre National de la Recherche Scientifique : UMR6554, EPHE - École pratique des hautes études, UNICAEN - Université de Caen Normandie, UBO - Université de Brest, UR2 - Université de Rennes 2, IGARUN - Institut de Géographie et d'Aménagement
Abstract : Mangroves have many ecological, socio-economic and climate change mitigation values and functions vital for the littoral populations around the world and in Madagascar.This richness induce them intense exploitation, subjecting to strong natural and anthropogenic pressures. However in Madagascar "the mangroves are very poorly understood and we do not have the elements necessary for a good diagnosis", while they are presented as of perpetual regression in the Madagascar Southwest region. This study aims at identifying, mapping and quantifying the evolution (since 1949) of 5 mangrove’s sites in the Southwest : Manombo-Fitsitike, Ambondrolava, Ankiembe, Sarodrano and Andriambe. It also aims the diagnosis of the different factors of evolution putting in perspective the anthropogenic and natural pressures. To achieve these objectives, two approaches were adopted : geomatics based on the diachronic analysis of Spot images from1987, 1998, 2012 and 2014 associated with aerial photographs (1949) and field work with floristic inventories, physico-chemical measurements, particle size analyzes of substrates and surveys. The results show complex and contrasting trend evolution’s dynamics between growth, stability and regression. In the end, based on the knowledge gained on the mangroves dynamic over more than 60 years, it is possible to make available to all a tool to help decision-making and sustainable and adequate management to protect and conserve these ecosystems, particularly in the context of climate change that will impact natural changes and anthropogenic forcing.
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Ricardo Andriatsiaronandroy Onjanamboara. Dynamique récente d'évolution des mangroves de la région de Toliara (Madagascar). Géographie. Université d'Angers; Université de Tuléar, 2018. Français. ⟨NNT : 2018ANGE0070⟩. ⟨tel-02890385⟩

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