The number of Sundari, the plant that defines the character of the Sundarbans, is decreasing remarkably, creating certain vacuum inside the once-dense mangrove forest.
A Chittagong University study reveals that the areas that have turned into vacant places in the Sundarbans in the past 25 years, would be 54,000 hectares.
The Sundarbans is a world heritage site announced by the UNESCO.
The mangrove plants declined about 25 per cent during the period, said the research conducted by Chittagong University’s forestry and environmental science institute with the help of US-based organisation Winrock International.
It has pointed out that the vacuum created in the forest would otherwise mean that the vacant areas could easily accommodate three cities equivalent to the size of port city of Chittagong with an area of 15,500 hectares.
The waning of the Sundari, which belongs to tree species Heritiera fomes, has threatened environment and biodiversity of the world's largest mangrove forest.
“The unabated consumption of firewood, increased use of Golpata trees [a kind of palm trees], rampant use of engine-run boats inside the mangrove forest can reduce the density of the forest in the coming days,” says the research styled Sundarbans’ Tourism, Protection of Habitations from Cyclone and Monetary Value of the Appropriated Resources, which was funded by USAID and John D Rockefeller Foundation.
Starting in November 2014, the research concluded in September 2017. A team, comprising CU economics teacher Mohammad Nur Nabi, former chief scientific officer art Bangladesh Space Research and Remote Sensing Organisation (SPARSO) Meherun Nesa and IUCN’s GIS analyst Imran Hassan, and led by the CU’s associate professor AHM Raihan Sarkar carried out the research.
The lead researcher told Prothom Alo that the main reason for decline in the number of Sundri is top dying disease, showing symptoms from the top of the main stem of the affected plant and gradual progression of the symptoms downward.
Many Sundari plants were destroyed during the cyclone Sidr and Aila.
However, he added, timber theft is a key reason for the decline.
According to the study, the area of Sundari trees had been reduced to 112,995 hectares in 2014 from 166,645 hectares in 1989.
Analysing satellite images obtained between 1989 and 2014, the researchers concluded that 63 per cent of the Sundarbans was covered by trees in 1989, but it came down to 38.18 per cent in 2014.
The deep forest of the Sundarbans is thus turning into thin forest, asid the study. When a forest is covered by 80-100 trees and sun rays rarely reach its soil, it is called deep forest and when such density declines to 50 per cent it is called a thin forest.
Deep forest protects soil from erosion and creates safe habitat for aninals, the researchers say.
Ishtiak Uddin Ahammed, a former country director of the International Union for Conservation of Nature (IUCN), told Prothom Alo that the Sundari trees normally grow in fresh water areas of the Sundarbans, but nowadays salinity is on the rise in the forest. Thus, he added, the Sundari trees are being the worst victims of deforestation.
“If such activities continue, the main features of the Sundabans and its biodiversity will be changed. The forest department should take immediate action in this regard.”
The forest department has banned collecting timber and shrimp fry for the past 20 years to protect the forest. But the researchers found that the ban has not been effective.
Md Amir Hosain Chowdhury, the conservator of the forest of Khulna range, said, the forest department has been working to increase the density of the forest.
"We prohibited collecting timber and shrimp fry at this time" he added.
In 1989, the Sundarbans had 29 per cent water reservoirs (rivers and canals) and 2.6 per cent empty lands. But as the density of the forest is decreasing, the amount of empty lands is increasing. At the same time, due to river erosions, the reservoir is also increasing, research says.
In 2014, the water reservoir in Sundarbans increased by 32 per cent while the empty lands became 8 per cent.
However, it is said that, the name Sundarbans was derived from the plant name Sundari, an evergreen plant with dark-grey or brown bark. The plants grow up to 15 to 19 metres. Sundari leaves are elliptic.
Not only Sundari, but also Gewa, another major plant in the forest, is decreasing day by day. In 1989, there were 132,477 hectares of Gewa plants that fell to 74,170 hectares in 2014.
In such context, the researchers have suggested restricting tourists in the Sundarbans for protecting its biodiversity.
The research also stressed on the law enforcing agencies’ role in stopping timber collection at the forest.
*This piece, originally published in Prothom Alo print edition, has been rewritten in English by Toriqul Islam.