Sundari tree, one of the most extensively found mangrove species in the Sundarbans, are disappearing for various diseases, including 'top-dying disease' which has killed 15 percent trees since the 80s.
In the last 30 years, 1.44 million cubic meter Sundari trees worth Tk 2,000 crore have been destroyed after being affected by 'top-dying disease', said experts.
Increasing salinity in the water and soil of the Sundarbans due to climate change is another reason for which the number of Sundari, Passur and Keora trees has been declining fast.
Gewa and Goran are being grown in the forest replacing Sundari trees.Gewa and Goran are now grown in 50 percent new places.
There are 334 species of trees and plants in 4,143-sqkm area out of6,017 sqkm.
According to experts, mangrove forest is grown in such a special natural environment where there is a mixture of specific proportion of saline water and sweet water. The change in the specific proportion of saline and sweet water causes harm to mangrove forest. Increase of saline water is fatal for Sundari trees, which is happening in the Sundarbans.
Top-dying disease in Sundari, while heart-rot disease in Pashur and die-back disease in Kewara have been behind their fast extinction.
'Top-dying' and 'Heart-rot' disease attacked the tress in 6, 14, 19, 20, 21, 25, 26, 27, 28, 32, 33, 36, 37, 38, and 39 compartments of the forest.
Noted water expert Ainun Nishat said Sundari trees have been dying due to the adverse effect of Farakka and lack of sweet water. "There are now 85.67crore Sundari trees in the forest which have been on extinction."
Md Bashirul-Al-Mamun, West Divisional Forest officer of the Sundarbans, said they found 30ppm salinity in the water which is decreasing the disease prevention capacity of the trees.
Dr Swapan Sarker, an associate professor at the Forest Environment Science of Shahjalal University of Science and Technology (SUST),in a research work mentioned that the diversity in the Sundarbans took a heat during 1986-2014. The number of Sundari, Passur, Shingra, Amur, Dhundal and Kakra trees are on the decline.