13.3.1
Mangroves
R. Ramesh . S. Ramachandran
The coastline of Bangladesh is dominated by mangrove and estuarine systems. The
western coast of Bangladesh is covered with dense mangrove forests called the
Sunderbans. There is heavy sediment deposition in the central region. Here, the coastline is dynamic, subject to continuous process of erosion and accretion. Besides being
a source of different renewable resources, the mangroves also serve as buffer zones
against cyclones and tidal surges. The Bangladesh coast supports'" 587400 ha of natural
mangroves (Mahmood 1986) and a further 100000 ha of planted mangroves.
The Sunderbans represent a complex estuarine ecosystem, dominated by dense forest
cover and periodical tidal inundations. The structure and composition of the
Supderbans are maintained by a strong salinity gradient extending from the freshwate~ environment of the northeast to the saline environment of the southwest
(Saenger et al. 1983). In mangrove areas, trees reach a height of up to 20 m, but the main
canopy is about 10 m. The natural Sunderbans vegetation is composed of halophytic
tree species dominated by Heriteria fornes, Excoecaria agallocha, Ceriops decandra and
Sonneratia ape tala. In the coastal afforestation areas, the most widely planted species
are Sonneratia sp., Avicennia officinalis, Avicennia alba, and Acacia sp. The densely
forested swampy islands are the home of a variety of animals ranging from large mammals, including tiger to innumerable mud crabs which, although common at the water's
edge can also be found throughout the intertidal zones. Major afforestation
programmes have also been underway since 1966 with the objective of
• accelerating the process of siltation and stabilisation of soil,
• create forest buffer belts to protect inland life and property from extreme events like
cyclones and tidal surges,
• create urgently needed resources to add to the national wealth,
• create job opportunities for rural communities and
• create a healthy environment for wildlife, fish and other fauna.
The Sunderban mangrove forests in the southwestern part of the country cover almost 600 000 ha. It IS the largest single compact mangrove resource in the world. An
Overseas Development Administration (aDA), UK sponsored survey in 1985 showed
tharthe standing volume of the main species has declined alarmingly in the Sunderbans
since the previous inventory 20 years earlier (Holmgren 1994). Over cutting and overestimation of regeneration times were reasons for a smaller inventory being recorded.
The Farakka Barrage across the border, which diverts as much as 40% of the dry season flow of the Ganga, causes increased salinity and this is another reason given for
impaired growth of the mangroves.
13.3.2
Coral Reefs and Seagrass Ecosystems
St. Martin's Island is the only coral reef island in Bangladesh. This gradually decaying
island is about 10 km south of the mainland, extending to a little over 7.5 km 2
(Haque et al. 1979). There is little information on the Bangladeshi offshore coral. A re-
Mangroves
R. Ramesh . S. Ramachandran
The coastline of Bangladesh is dominated by mangrove and estuarine systems. The
western coast of Bangladesh is covered with dense mangrove forests called the
Sunderbans. There is heavy sediment deposition in the central region. Here, the coastline is dynamic, subject to continuous process of erosion and accretion. Besides being
a source of different renewable resources, the mangroves also serve as buffer zones
against cyclones and tidal surges. The Bangladesh coast supports'" 587400 ha of natural
mangroves (Mahmood 1986) and a further 100000 ha of planted mangroves.
The Sunderbans represent a complex estuarine ecosystem, dominated by dense forest
cover and periodical tidal inundations. The structure and composition of the
Supderbans are maintained by a strong salinity gradient extending from the freshwate~ environment of the northeast to the saline environment of the southwest
(Saenger et al. 1983). In mangrove areas, trees reach a height of up to 20 m, but the main
canopy is about 10 m. The natural Sunderbans vegetation is composed of halophytic
tree species dominated by Heriteria fornes, Excoecaria agallocha, Ceriops decandra and
Sonneratia ape tala. In the coastal afforestation areas, the most widely planted species
are Sonneratia sp., Avicennia officinalis, Avicennia alba, and Acacia sp. The densely
forested swampy islands are the home of a variety of animals ranging from large mammals, including tiger to innumerable mud crabs which, although common at the water's
edge can also be found throughout the intertidal zones. Major afforestation
programmes have also been underway since 1966 with the objective of
• accelerating the process of siltation and stabilisation of soil,
• create forest buffer belts to protect inland life and property from extreme events like
cyclones and tidal surges,
• create urgently needed resources to add to the national wealth,
• create job opportunities for rural communities and
• create a healthy environment for wildlife, fish and other fauna.
The Sunderban mangrove forests in the southwestern part of the country cover almost 600 000 ha. It IS the largest single compact mangrove resource in the world. An
Overseas Development Administration (aDA), UK sponsored survey in 1985 showed
tharthe standing volume of the main species has declined alarmingly in the Sunderbans
since the previous inventory 20 years earlier (Holmgren 1994). Over cutting and overestimation of regeneration times were reasons for a smaller inventory being recorded.
The Farakka Barrage across the border, which diverts as much as 40% of the dry season flow of the Ganga, causes increased salinity and this is another reason given for
impaired growth of the mangroves.
13.3.2
Coral Reefs and Seagrass Ecosystems
St. Martin's Island is the only coral reef island in Bangladesh. This gradually decaying
island is about 10 km south of the mainland, extending to a little over 7.5 km 2
(Haque et al. 1979). There is little information on the Bangladeshi offshore coral. A re-