Biodiversity

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BIODIVERSITY

The Indian part of Sundarban region is located in the state of West Bengal occupying the lowest part of the Ganga delta which has been fragmented by various distributaries. This littoral tract, experiencing tidal waves at regular interval from the Bay of Bengal, has provided conducive hydrogeomorphological conditions for the development of wild mangrove ecosystem with highly diversified floral and faunal species. Estuarine ecosystem is in fact maintaining a linkage between the terrestrial and marine ecosystems. The lowest part of the delta where the process of land formation is still active is experiencing fresh water discharge through the river Ganga, locally known as Hugli and its distributaries half of the day and counter flow of brackish water in the other half. Agricultural landscape dotted with fresh water pond ecosystem can be found beyond the northern limit of the virgin forest. Combination of so many ecosystems in the proximity of Bay of Bengal has made all of them fragile whenever exposed to the onslaught of natural hazards like cyclone and tidal surge or subjected to over exploitation of the wild and aquatic resources by the human society thus disturbing the delicate balance of the nature. Consequently three dimensions of biodiversity species, gene and ecosystem all are suffering from negative impact of their onslaught.

Sundarban region is composed of 102 islands of which 48 are still under the cover of forest and rest of the 54 have already been deforested with subsequent conversion to arable land studded with human settlements, orchards and tanks. Northern limit of this region is known as Dampier and Hodges line. The river Hugli and the international boundary between India and Bangladesh form the western and eastern limits of the region respectively. In terms of administrative identity this region is a combination of 19 Community Development Blocks out of which 13 are under the jurisdiction of South 24 Parganas district while six other Community Development Blocks are under the district of North 24 Parganas. The Sundarban forest is inundated daily, during high tides by innumerable interlacing creeks. The western stretch of forest and swamp lies between 21° 30’ 40" and 22° 3’ 30" north latitudes and 88° 4’ 30" and 91° 14’ east longitudes. The total geographical area of Indian Sundarban is about 9630 square kilometers. The rest of the Sundarban region lies within Bangladesh.

Sundarban is recognized as one of the world heritage centre in 1987. In the year 1989 it was declared as "Biosphere Reserve". Sundarban forest contains 64 species of mangrove variety. This littoral forest is the abode of 40 species of mammals, 45 species of reptiles, 150 species of birds, 200 species of fish, 40 species of crabs, 25 species of prawn and 6 species of frogs. Two horn Rhino and water loving wild buffalo have become extinct in the nineteenth century. Gradually hog deer and barking deer, Indian Muntjac and soft shell turtle also suffered from extinction. Gangetic dolphin is rare now. So many mangrove species have become endangered as revealed from the recent surveys. List of Endangered Flora in Sundarban : 1]Kankra, 2] Golpata, 3] Sundari,4] Goran, 5] Keora, 6] Ohundhal, 7] Passur [Source: Arboretum Swaminathan Project]. Impact of this endangered state of many mangrove species has led to the disturbance in the mangrove ecosystem which is highly sensitive and responds to any change promptly, because it is playing the role of a dynamic ecosystem. The list of endangered fauna in Sundarban is lying with the fifth schedule and after necessary amendments since 1972, the following list is prepared : List of Endangered Fauna in Sundarban 1] Estuarine Crocodile , 2] Gharial, 3]Olive back Logger Head Turtle, 4]Common Batagur, 5] Gangetic softshelled Turtle, 6] Water Monitor, 7] Yellow Monitor, 8] Indian Monitor, 9] Python, 10] Olive Ridley

Turtle [ Source: Naskar, 1999]. Various anthropogenic factors are responsible for such a state of affairs. These endangered species are falling prey to the greed of saw mill owners and poachers of the wild animals on one hand and to hunger of people etc on the other.

In fact diversified relationship among flora and fauna govern the issue of biodiversity in Sundarban forest. Brackish tidal waves, saline alkaline soil and the mangrove species maintain a symbiotic relationship among themselves. Herbivores compartmentalize the forest horizontally and vertically depending on their food habit as well as nesting habit. Deer occupy the lowest stratum, monkeys stay in the middle and avifauna dominate the top most branches of the trees. Since they are not competitors to one another they usually maintain a relationship of peaceful coexistence. In ecotones, competition for food and shelter is the order while deer and tiger maintain an eternal prey predator relationship.

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