Phytosociology and Mangrove Ecology in Trincomalee and Implications for Conservation

Abstract

Mangrove forests are one of the intertidal wetlands dominating the tropical and subtropical coasts. They are keystone ecosystems providing pivotal ecological and economic services and have acknowledged roles in coastal productivity and connectivity. However, increasing natural and anthropogenic disturbances have imposed a question on their sustainability. Proactive mangrove conservation requires science-based inputs at local and regional levels. Considering above, the present study aimed to investigate the floristic structure, phytosociology, and the ecological linkage of floral assemblages in a mangrove forest in Trincomalee, Sri Lanka. Forest survey was done with 10m wide belt transects of different lengths at ten stations in the site (P1-P10). Mangroves along the transects were identified, enumerated, and measured diameter at breast height (DBH). Forest structure was assessed with a value index and niche width. Subsurface water samples were taken from the stations to measure environmental parameters (n=30). Floristic survey revealed a heterogeneous mixture of five mangrove species. Overstory was dominated by Avicennia marina, Luminitzera racemosa, and Rhizophora apiculata. R. apiculata showed the highest niche width (9.77). The site revealed a Shannon index of 1.08, Simpson index of 0.38, and Pielou’s evenness of 0.69. Cluster analysis classified the sites into two groups, which were then used to perform site-specific discriminant analysis of floral assemblages. Distance-based redundancy analysis (dbRDA) showed that salinity, dissolved oxygen, tidal amplitude are key factors controlling mangrove assemblages in the site. The data presented in the study would be fundamental in site-specific management and implementing conservatory actions