Dr. Moniruzzaman Khondker

Abstract: Human (Homo sapiens L.) population density on the habitable land area of our planet is estimated to be 122.21 ind km-2. Men use resources of habitable lands for their colonisation, agriculture, industrialisation, habitat building, resource extraction and for a number of other purposes. As a result our natural resources are dwindling. Mangrove, a forest resource has been existing on earth since 7000 years and are utilised by men strongly. It is composed of a specialised biodiversity having adaptive features suitable to colonize in estuaries, and shallow zones where rivers meet oceans. World’s mangrove forests occupy 180,000 km2 and are distributed along 16ºC winter isotherms. Of the whole forest area, ~58% belongs to 8 countries. These are Indonesia (23.5%), Brazil (7.3%), Australia (6.3%), Nigeria (5.8%), Cuba (4.3%), India (3.7%), Malaysia (3.2%) and Bangladesh (3.2%). However, worlds single largest unit of mangrove forest (Area,10000 km2) known as Sundarbans is situated in the greater Gangetic delta Bangladesh (6000 km2) and West Bengal, India (4000 km2). The Sundarban forest lies in between 21º31’ and 22º30’ N and 89º and 90º E and it has been declared as UNESCO world heritage site. The dominant plants are Heritiera fomes and Excoecaria agallocha contributing 29.7% of Sundarbans. Endangered Panthera tigris and spotted deer and Crocodylus porosus are common. Nearly 31,762 mt Nypa fruticans, 66,578 pieces of Ceriops decandra, 233 mt honey, 3485 mt fish and many other products are extracted from the Sundarbans annually. About 150037 tourists visit every year. The forest supports the livelihood of ~300,000 - 600,000 peoples for half a year period. Mangrove holds the most C rich biomass (937 mt/ha) of the world with a C sequestration rate 13.5 Gt y-1. Via mangrove forest, ca 174 gC m-2 y-1 are buried underneath soil. In the forest ecosystems, 33.63-81.25% decrease in the C-pool occurs after 10 years of deforestation. Overexploitation, navigation increase, unusual sedimentation, sea level rise, freshwater abstraction from upstream, salinity increase, top dying disease, etc. are the identified reasons for the destruction of world’s mangrove forests. Forest management with adequate afforestation programs are suggested to protect the mangrove forests of the world.