Mangrove Forest Composition and Vegetation Small Islands at West Pasaman

Composition and vegetation of mangrove ecosystem in an area including that grown in small islands is different and depends on ecology and ecosystem of the islands. The purpose of the research is for getting the information of composition, vegetation structure and mangrove type that grown an each small islands in west Pasaman area. The method use was a survey of the field to get the type, composition and vegetation structure of each island by using transectsquares technique.In the research that has been done on several islands in the West Pasaman (Taming Island, Harimau Island, and Panjang Island), have been identified plants on Tamang Island that had 15 species and 11 families, which 2 families and 5 spesies were categorized as true mangroves and the dominant spesies is R. stylosa with important value index (IVi) is 192.88%, on Harimau Island found 36 species and 24 families, which 9 species and 4 families were categorized as true mangroves and the dominant is R. apiculata with 229.82% (Vi), while on Panjang Island found 18 plant species and 14 families, which 5 species and 2 families were categorized as true mangroves, the dominant species is R. mucronata with 92.98%. From each island showed composition, vegetation structure and different dominant spesies and this different is caused by the dominant substrate fand on each island.