Impact of Anthropogenic Activities and Climate Change on the Wetlands in the North-West of Madagascar.

Macrophytes are vulnerable to various factors in their natural ecosystems, including climatic, ecological, and anthropogenic changes. This study aims to document how these factors influence floristic composition. Four sites were investigated in the Boeny Region of northwest Madagascar: Ambatoboeny, Marovoay, Ankarafantsika National Park, and Mahajanga II. Floristic inventories were compiled with geographic and floristic parameters, utilizing 1 × 1 m2 quadrat for each sample. Diversity indices, Analysis of variance (ANOVA), distance based-Redundancy Analysis (db-RDA) were conducted to analyze the data. A total of 98 species were recorded across the four study sites, belonging to 73 genera and 33 families. Twelve species were unique to Mahajanga II, 18 to Marovoy, 16 to Ankarafantsika, and five to Ambatoboeny. Rarefaction curves indicated a progressive trend in species diversity, which appeared to stabilize in both Shannon diversity. The db-RDA revealed species dispersion along longitudinal and latitudinal axes and in relation to vegetation cover. The Permutational Multivariate Analysis of variance (PERMANOVA) indicated a significant influence among the study sites. Over the course of two decades, we observed an increase in temperature at the three districts including the study sites, while precipitation levels progressively decreased during the same period. Wetlands in the northwestern part of Madagascar are in need of conservation and would benefit from further research.