Floristic Diversity of Riparian and Associated Vegetation Along the Amnay River (The Philippines)

Riparian vegetation plays a critical role in maintaining ecological integrity along river corridors, yet it is highly sensitive to changes in hydrological and geomorphic conditions, particularly in sediment-influenced tropical river systems. In many Philippine rivers, increased sediment deposition and landscape disturbance have altered riparian structure and floristic composition, underscoring the need for site-specific baseline assessments. This study aimed to document the floristic composition, vegetation structure, and spatial patterns of riparian vegetation along the downstream reach of the Amnay River in Occidental Mindoro, Philippines, as a baseline for understanding current riparian conditions in a sediment-influenced river corridor. Vegetation surveys were conducted using transects and quadrats established along the riverbanks, where species composition, growth form, and structural attributes were recorded. Species importance values and diversity indices were calculated to characterize vegetation dominance and diversity patterns across sampling sites. Riparian vegetation communities were mapped to describe spatial distribution and fragmentation. A total of 125 plant species representing 40 families were recorded, with vegetation dominated by herbaceous and disturbance-tolerant taxa, particularly members of Poaceae and Fabaceae. Woody vegetation was limited and occurred mainly as isolated remnant patches, resulting in low vertical complexity and fragmented spatial structure. Species diversity varied among sampling sites, reflecting localized differences in substrate stability and vegetation cover. The findings provide a baseline characterization of riparian vegetation in a sediment-influenced tropical river system and highlight the persistence of remnant woody vegetation within an otherwise simplified riparian corridor. This baseline information is essential for future monitoring, comparative studies, and the evaluation of riparian management and restoration efforts.