The Sundarbans mangrove is a highly dynamic ecosystem. Gewa (Excoecaria agallocha Linn.) is a codominent species, the merchantable growing stock of which was depleted by 45% during 1959 to 1983. The purpose of this study was to obtain information on phenology, genetic diversity, improvement of selection, and suitable propagation system and hedge development and management as a step towards sustainable management of the species and enhances the productivity of the mangrove forests. Gewa is a commercially important hardwood species. So it is an urgent need to improve this species for maintaining and protecting its genetic erosion. The present situation calls for improvement and management of this species for sustainability of the forest. The seed viability decreases very rapidly within a short time. Natural regeneration of gewa is limited due to several biological factors. Shortage of superior seeds/propagules for plantation forestry may be overcome by using clonal propagation technique. The results suggest that, to increase the timber yields, productivity and sustainability of the forest, enrichment plantation by genetically superior stocks is possible in the mangrove forest.