Anthropogenic impacts on vegetation diversity and spatial floral composition of the swamp forest associated with the tropical river basin

The Gin river wetland marsh has been identified as one of the most dynamic ecosystem in Sri Lanka, providing habitats for associated floral and faunal communities under a permanent or temporary accumulation of water. Study was focused to understand the structure, composition and threats of the Ginthota wetland marsh, by identifying the biodiversity distribution, anthropogenic activities and evaluation of water quality changes. Vegetation was sampled in randomized plots and water samples were collected in the three sampling locations. Fifty seven species of plants of twenty three different families were identified. Out of them, forty eight species were native and five were introduced. Argyreia populifolia was identified as an endemic species. Three plants were identified as dominant plant species Sonneratia caseolaris, Annona glabra and Acrosricum auriyam. Annona glabra was an invasive species and Nypa fruticans was an endangered species. The Shannon-Wener Index for the disturbed and undisturbed areas was 0.685 and 1.721 respectively, reflecting a higher biodiversity in the undisturbed areas. Many anthropogenic factors are causes for the deteriorating diversity and also water quality.