SUNDARBAN

The Sundarbans of Bangladesh consist of over 4,000 sq. km. of mangrove forest. It extends westwards into India and is the largest mangrove forest, followed by the mangrove forests of Irian Jaya. Protected as Reserved Forest since 1875, the entire area is flat and intersected by a complex network of streams and rivers (of which the larger channels run in a generally north south direction), with the salinity increasing from east to west and towards the south. Salinity plays an important role in the growth, species distribution and productivity of the forest, and vegetation tends to be more luxuriant at lower salinity levels. The greater part is covered with tidal swamp consisting of a mosaic of mangrove forest types differing considerably in species composition. The main type is dominated by Sundri (Heritiera fomes), which grades into low stature stands with mixed sundri, Gewa (Excoecaria agallocha) and Goran (Ceriops decandra).

The Sundarban is home to 32 mammal species, at least 186 bird species and 43 reptile and amphibian species. The Sundarbans provides ideal habitats for the mammals, waders and seabirds and also suitable nesting sites for both marine turtles and the endangered estuarine terrapin (Batagur baska). Several large species, such as the Javan rhinoceros and the water buffalo, have disappeared since the beginning of this century. Above all the Sundarbans are well known as the home of the Royal Bengal Tiger (Panthera tigris tigris), whose population is estimated at 350 to 600, one of the largest surviving populations in the world. Over 120 species of fish are caught by commercial fishermen, and the area is an important nursery for both offshore and near shore marine and brackish fish species, with crustaceans accounting for the largest proportion of animal biomass. The flora is rich, with 69 species.

The Sundarbans are heavily utilized. One-third of the local population depends in one way or the other on the mangroves for their livelihood. Gewa and Sundri are felled on a 20 year life cycle, they provide high quality timber for newsprint, match sticks and boxes. Sundri alone constitutes 63.8 percent of the total marketable timber. Non-timber products contribute significantly towards the overall productivity of the Sundarbans. Leaves of Nypa fruticans are traditionally used for roof thatching and house walls. Trunks of Phoenix paludosa are in great demand as house posts. Ceriops decandra and Cynometra ramiflora yield high quality fuel wood. An estimated 185,000 kg of honey and 44,400 kg of wax are harvested each year in the western part of the forest. Commercial fishing takes place along the waterways all year long.

The Sundarbans has been managed for over 120 years as a commercially exploited Reserved Forest. The original intention was for a 20-year felling cycle, with "improvement felling" consisting of removing dead, dying and unsound trees and thinning congested areas. Different exploitable diameter limits are enforced for different species in various quality classes, largely determined by salinity. Diameter limits and felling cycles have been adjusted over this time, and improvement felling is no longer carried out. Nypa fruticans leaves are harvested once a year, and the central leaf and leaf next to it are retained. Fuel wood and pole species are harvested on a 20-year cycle. In 1966 the Forest Department program to plant mangroves for protection and to encourage land accretion outside the coastal embankments was initiated. After ten years, 300 sq. km. had been planted in rotation. The World Bank now supports the project.

Management of the Sundarbans faced a process of continuous change, much of which has been beyond the control of the Forest Department. The major recent change in the physical environment of the Sundarbans is a reduction in the amount of freshwater flowing into the area as a result Salinity levels have increased, lowering productivity. This is due to natural changes, river diversions and withdrawal of fresh water upstream. It is believed to be the cause of unusual mortality in some areas of the main commercial species sundri, especially since 1970. Silt is deposited in the northeast portion of the forest, causing the forest floor to rise, which stresses mangrove plants. Productivity has declined significantly over the last few decades and the average yield of wood is only 1.12 cubic meters/hectare/year (cu m/ha/yr). The standing stock of Sundri and Gewa was depleted by 40 and 45 percent, respectively, between 1960 and 1985. A number of factors, including over-exploitation, may have contributed to this. There may be a need for revision of the current silvicultural system in order to maintain a sustainable level of production. It seems unlikely that the trend of decreasing freshwater discharge can be reversed, indeed the problem is likely to be aggravated by a rise in sea level caused by global warming.

At present, the Sundarbans is entirely dependent on natural regeneration. Seedlings are abundant throughout most of the forest, averaging 27,750/ha per year, but their survival is a major problem for most species at all levels of salinity. An additional problem is "top-dying," a phenomenon that causes death of trees from the top downwards and that is increasingly affecting Sundri; 17 percent of trees are moderately or severely affected. The cause of this is not known, but it could be the result of stress from a variety of factors such as changes in salinity, reduction in flooding levels, loss of canopy leaves in storms or siltation of the pneumatophores. Reforestation, or supplementing natural regeneration by planting, may be necessary. Other species could be planted on elevated soils, and trials are underway.

The Forest Department also regulates fishing within the Sundarbans, but there is no information on the status of fishery resources. There is no regulation of the collection of shrimp fry, and the use of set-bag nets destroys fish larvae and depletes juvenile fish. Stock assessments of commercially important fish, crustaceans and mollusks are urgently needed for developing a management plan.

In 1977 three wildlife sanctuaries were declared. These are the 91sq. km. Sundarbans West Wildlife Sanctuary, the 179sq. km. Sundarbans South Wildlife Sanctuary and the 54sq. km. Sundarbans East Wildlife Sanctuary. In 1978, under the joint WWF/IUCN Project Tiger, a management plan was prepared for the tigers in these sanctuaries, but it has not yet been implemented.

Despite its international importance and its long management history, there are still outstanding needs for the long-term survival of the Sundarbans. The two main ones are need to investigate the potential for developing ecotourism, as the Sundarbans could be a major attraction; at present the lack of accommodation and transport means that tourism is not a feasible source of revenue for local people. Second, management-oriented research is required, particularly on wildlife and threatened species; on the causes of low mangrove productivity, die-off and seedling failure; and on the fisheries.

The Sundarbans from space. The dark red portions are the Sundarbans. The extent of silt flowing into the Bay of Bengal can be clearly seen.

Articles and Write-Ups on the Sundarbans -

Protecting the Sundarbans - Khushi Kabir (Daily Star)

UNESCO - World Heritage site Description