The world largest mangroveforest, Sundarbans is situated at the westerncoastal zone of Bangladesh that covers about 40% of the total forest and gives good feedback to the national economy. But for last few years, salinity increasing drastically in this particular region due to sea water intrusion, reduction of fresh water flow and human activities like shrimp farming. In this study both field survey (primary data) and historical
(secondary) data were used to assess the present status of salinity rise in Sundarbans area as well as the effect
of salinityrise onspecies destruction like Sundari(Heritiera fomes) which is the climax species of Sundarbans. It was observed that sea level is rising in the Sundarbans coast at the rate of 4 mm/year that ismuch higher than global trend of 2 mm/year and results more areas to inundate by tidal water. Besides, the water diversion and withdrawal of fresh water in the upstream significantly hampering salt balance system in Sundarbans that leads to permanent and high level of salinity. The soil salinity rise increases with the increase of depth of soil and high level of salinity in the root zone of the plants results a high concentration of sodium salts within the plants
body that causes to the reduction of the forest production, restricting the growth of the species like Sundari (Heritiera fomes) and even causes to die.