sunder bans, bangladesh

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Md. Mustafizur Rahman @ Rashed; Dept. of Zoology; Rajshahi UniversityWe portion out among them their livelihood in the life of the world, and We exalt some of them above others in degrees, that some of them may take others in subjection. (Sura- Zukhruf: 32) Do they not see that We drive the water to a land having no herbage, then We bring forth thereby seed- produce of which their cattle and they themselves eat? (Sura- Assajdah: 27)

Characterizations of some important terms (definitions):Accipitridae: The family of predatory birds including hawks, eagles, and kites. Ecosystem: Ecosystem is a localized group of interdependent organisms together with the environment that they inhabit and depend on. Fauna: The animal life of a particular region or period, considered as a whole. Flora: Plant life, especially all the plants found in a particular country, region, or time regarded as a group. Food chain: Food chain is a hierarchy of different living things, each of which feeds on the one below. Food-web: The interlocking food chains within an ecological community Gastropod: Mollusk that has a head with eyes, a large flattened foot, and often a single shell, e.g. a limpet, snail, or slug. Halophyte: A plant capable of growing in salty soil Mangrove: Mangroves are trees or bushes growing between the level of high water of spring tides and a level close to but above mean-sea level. Pelecypod: Saltwater or freshwater invertebrate animal that has its body contained within two shells joined by a hinge. E.g. oysters, mussels, and clams.

The Sunderbans:

The Sunderbans Cli matic condition C hief animal Species Effects of cyclone SIDR in Sunderbans ecosystem Geographical presentation Individuality of Sunderbans Ecosystem of Sunderbans Sunderbans after SIDR Derivation of name Personalities of mangrove plants Working of Sunderbans ecosystem Management of Sunderbans ecosystem Sunderbans in different time Major Flora of Sunderbans Economic significance Geology of Sunderbans Chief plant species Attractiveness Soil condition Major Fauna of Sunderbans Threats of Sunderbans

Sunderbans, the largest single block of tidal halophytic mangrove forest in world. With its collection of trees and wildlife the jungle is a showpiece of natural It is also a mid point of economic activities, such as extraction of timber, fishing and collection of honey. The forest consists of about 200 islands, separated by about 400 interconnected tidal rivers , creeks and canals. The vast mangrove forest listed as a Heritage Site by the UN cultural organization UNESCO.

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Geographical presentation:Sunderbans is positioned in the southern part of Bangladesh. It lies the estuaries of the Meghna and Hugli (Hooghly) rivers (GangesBrahmaputra delta) at the point where it merges with the Bay of Bengal. It extends about 274 km (170 mi) along the Bay of Bengal and about 100 km (62 mi) inland. The forest lies a little south to the Tropic of Cancer between the latitudes 2130N and 2230N, and longitudes 8900E and 8955E. The total volume of this forest in Bangladesh is about 2316 sq. mile.

Derivation of name:The Bangla word ban means forest, and the name Sunderban was coined either from the forests of Sundari tree i.e. Sundari-ban, or from the forests of the samudra (sea) i.e. Samudra-ban, or from its association with the primitive tribe Chandra-bandhe which was corrupted into Sunderban. The generally accepted explanation, however, is its derivation from the sundari tree, the most common tree in these forests.

Sunderbans in different times:Sunderbans was originally measured (about 200 years ago) to be of about 16,700 sq km. Now it has diminished to about 1/3 of the original size. Because of the partition of India, Bangladesh received about 2/3 of the forest; the rest is on the Indian side. It is now estimated to be about 4,143 sq km, of which about 1,874 sq km is occupied by water bodies. The forest lies under two forest divisions and four administrative ranges- Chandpai, Sarankhola, Khulna and Burigoalini and has 16 forest stations. It is further divided into 55 compartments and 9 blocks. The Sunderbans was declared as a Reserve Forest in 1875. About 32,400 hectares of the Sunderbans have been declared as three wildlife sanctuaries, and came under the UNESCO World Heritage Site in 1999. These wildlife sanctuaries were established in 1977 under the Bangladesh Wildlife (Preservation) (Amendment) Act, 1974. These are Sunderbans West (9,069 ha), Sunderbans South (17,878 ha), and Sunderbans East (5,439 ha).

Geology of Sunderbans:The band of the Sunderbans is of recent origin, raised by the deposition of sediments formed due to soil erosion in the Himalayas. The process has been accelerated by tides from the sea face. The substratum consists mainly of Quaternary Era sediments, sand and silt mixed with marine salt deposits and clay. Geologists have detected a south-eastern slope and tilting of the Bengal basin during the Tertiary. Because of neo-tectonic movements during the 10th-12th century AD, the Bengal Basin titled eastward. Evidence

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from borehole studies indicate that while the western side of the Sunderbans is relatively stable, the south-eastern corner is an active sedimentary area and is subsiding.

Soil condition:Soils of the Sunderbans mangrove forest vary from other inland soils in that they are subjected to the effects of salinity and water logging, which naturally affect the vegetation. In places soils are semi-solid and poorly consolidated. The pH ranges widely from 5.3 to 8.0. Although the Sunderbans soil is in general medium textured, sandy loam, silt loam or clay loam, the grain size distribution is highly variable. Silt loam is dominant textural class. Sodium and calcium contents of the soil vary from 5.7 to 29.8 meq/100g dry soil and are generally low in the eastern region and higher towards the west. The available potassium content of the soil is low, 0.3-1.3 meq/100g dry soil. Organic matter content varies between 4% and 10% in dry soil. Soil salinity increases from east (slight to moderate) to west (highly saline), but the salinity is not uniform from north to south throughout the forest.

Climatic condition:Since the forest is located on the south of the Tropic of Cancer and bounded by the northern limits of the Bay of Bengal, it is classified as tropical moist forest. The temperatures in the Sunderbans are fairly equable than those of the adjacent land areas. The average annual maximum and minimum temperatures vary between 30 and 21C. High temperatures occur from mid-March to midJune and low in December and January. The mean maximum temperature for the hottest months has been recorded as 32.4C at Patuakhali, in the east of the Sunderbans. The mean annual relative humidity varies from 70% at Satkhira to 80% at Patuakhali. Humidity is highest in June-October and lowest in February. Annual rainfall in the Sundarbans is in the range of 1640-2000 mm, rainfall increases from west to the east. Most rainfall occurs during the monsoon from May to October. Frequent and heavy showers occur from mid-June to mid-September. Often storm accompanied by tidal waves result widespread inundation and cause damage to vegetation and animal life.

Individuality of Sunderbans:Sunderbans, the littoral forest is the only ecological habitat of the tiger of its own kind not only in Bangladesh but also in the world except in India. The typical littoral forests of Sunderbans comprises of a host of trees species adopted to the peculiar estuarine condition of high salinity, lack of soil erosion and daily inundation by high tides. The tidal forms and the mangrove vegetation in Sundarban are responsible for dynamic eco-system vigorous nutrient cycling both terrestrial and aquatic. The whole eco-system is sensitive to change in salinity and the continuous cycle of erosion and deposition is affecting the plant communities giving rise to dynamic floristic changes. The plant communities are continuously adjusting to the new conditions. The uniqueness of the habitat is said to have contributed to certain behavioral trends, which are characteristic of Sundarbans tigers only. It is considered that man-eating propensity of tiger in this area is hereditarily acquired over a period of generations in the process of consumption of saline water. Cheetal, wild boar, rhesus macaque are the main prey species of tiger. Tiger fern (Achrostichum aureum) mostly covers the ground floor, which is common in saltwater and moderately saltwater zones. Tigers use these bushes to camouflage themselves. Aquatic animals like the crabs and fishes are also eaten by Sundarban tiger which occupies the pinnacle of both terrestrial as well as aquatic food-web. Sunderbans mangrove is the home of a number of endangered and globally threatened species. The Royal Bengal Tiger and the fishing cat are getting effective protection here. The creeks of Sundarbans form the home of Estuarine Crocodile, Salvator Lizard, River Terrapin and Horse Shoe or King Crab. This area serves as the nesting ground for endangered marine turtles like Olive Ridley, Green Turtle and Hawk's Bill Turtles. The aquatic endangered mammals like Genetic Dolphins thrive within mangrove creeks close to sea. A number of heronries form here during monsoon as well as during winter. It is home for Trans-Himalayan migratory birds.

Personalities of mangrove plants:Mangroves are halophytes: plants which naturally complete their life cycles under saline conditions. A saline environment poses a number of problems to the functioning of plants. In the first place uptake of saline water deregulates the osmotic pressure in the cells. The osmotic potential is generated by dissolved solutes in the cell sap. Thus, the intracellular concentrations of such solutes must increase with increasing salinity if cellular osmotic potentials ar