study of the Sundarbans needed

study of the Sundarbans needed

By Dr.Fourkan Ali

Whether one has ever seen it or not, the Sundarbans pervades our national conscious as a legend, a treasure and a heritage. It may not be anything as big as the Amazons, which controls the climate of continents; the Sundarbans’ influences over the whole of Bangladesh are immense.

It provides the people, not only of neighborhood but also in distant places, with fuel wood, despite curbs on cutting trees. And this is much in an energy hungry land, especially the rural areas. It is also the source of raw materials for the only newsprint mill of the country. The Sundarbans also provides golpata used for thatching huts in the rural areas. It is famous for honey throughout the country. And the whole Sundarbans is a great hunting ground for fish. It provides shelter and habitat for hundreds of species of animals and birds, including the Royal Bangle Tiger. It is the home of several species of trees and shrubs l to the economic life of the people and sources of medicines.

A large number of fishes inhabit the innumerable rivers, canals and creeks that cress-cross the entire Sundarbans. Braving danger to life many people go into the Sundarbans to gather wood, golpata and honey Thousands of, and some time over a hundred thousand, people enter the forest area to fish. But many like us, the city dwellers, go there to have fun or if possible to see the Royal Bengal Tiger.

Very few people go there for a scientific study of the forest and its environment. But two such scientific expeditions to the Sundarbans, led by late Prof, M. I. Chowdhury had been undertaken -Y one in late 1965 and the other in 1967. The first team went there during the dry season. It consisted of over 30 experts from different disciplines, including geography forestry microbiology, etc. They stayed there for nearly a month. The papers they produced were mostly published in a supplement on the Sundarbans brought out by the Morning News in early 1966. The other expedition was conducted during the monsoon. But the team this time could not stay there beyond a fortnight because of inclement weather against which there was not enough protection. The expedition also suffered due to paucity of funds.

Here I should beg apology for writing on the Sundarbans because I had only a fleeting glimpse of the great forest during a trip to Khulna by steamer as late as the late 1980s. One of my friends. had arranged the trip for me to the Sundarbans. But we could not go very far down the Ruphsa as the river as well as the sea had been rough and our vessel was not properly equipped for such a trip. We traveled for about 45 minutes and then returned to Mongla Port for our lunch. But the only thing I leant from a distance was that the golpata was not round after all as it suggests in Bangla language. And I did not have the chance to see the breathing roots of the mangrove forests of which I have read so much.

My contention, therefore, is that very little on-the-spot study has been done on the Sundarbans in which we take great pride as it is said to be the largest mangrove forest in the world. We really don't know much about this great forest and the multitudinous life forms that it harbors. We don‘t even have a history of the Sundarbans, its origin, progress and the threats of depletion being faced by the forest from various quarters. It is a good thing that the UNESCO has declared the Sundarbans as a World Heritage Site. But this is only the beginning. We should follow it up with groundwork of scientific studies to really know what heritage we inherit.

The Sundarbans is left entirely in the care of the Forest Department. But they do not have adequate manpower and equipment to monitor and carry on surveillance over the vast tracts of the forest. Moreover; the forest officials are not properly trained but are mostly ordinary government employees.

Now that the UNESCO has declared the Sundarbans as a World Heritage Site, the government should come forward to chalk out an elaborate plan in cooperation with the UN and international agencies. Such move should help in protecting the flora and fauna of this great mangrove forest. The authorities should also set up scientific research stations in the Sundarbans to study different physical, biological and environmental aspects. This will certainly help us in our main pursuit of protecting the Sundarbans mangrove forest, its trees and animals for our posterity.

The Sundarbans ecosystem

The Sundarbans is the world's single largest mangrove forest that extends across Bangladesh and the Indian state of West Bengal. Centuries ago, people used to refer to the Sundarbans and its adjacent region as `Bhatia’ - meaning low-lying areas -- which suggest that the most important physiographical feature around was its wetlands and water bodies. A unique reservoir of bio-diversity the forest is more than five thousand years old. There is no archeological evidence that could provide a reliable chronological history of the Sundarbans.

Bangladesh owns about two thirds of the format that makes about 45 percent of the country's total productive forest area Located on the southern most extremity of Bangladesh, the Sundarbans comprise an extensive flat, coastal and deltaic land formed by the confluence of the three mighty rivers of the Ganges, Brahmaputra and Meghna It is cross-crossed by large tidal rivers as well as channels and creeks, all discharging into the Bay of Bengal.

The forest encompasses a land area of 6017 sq km, of which 1874 sq km constitute the river water area. The forest is bordered to the south by the Bay of Bengal while polders and a 'cultural land border the forest to the north. The western border follows the Raimangal- Harinbhanga Rivers, which is also forms the international boundary with India. To the east lies the Bales war river and Meghna estuary.

 There are rivers and canals spread across this forest like a net with their innumerable branches. Nearly 450 large and small rivers occupy about 1 lakh 75 thousands 685 hectares or about 50 per cent of the Sundarbans. The biggest river is the Pusur. Other rivers worth-mention are Bales war Sibsa, Ar-pangasia, Bhola, Horlnbhanga, Kalindi, Andharmanik, Raimangal, Kapotaksha, Koira, Shela Bhadra etc. As one proceeds to the south, the rivers widen. Some rivers are so wide that one cannot see one bank from the other. Bales war and Pusur rivers and their tributaries and distributaries are connected with the Ganges. As a result these rivers and their branches have flow of sweet water The Sibsa and other rivers in the western part have their source of sweet water only in the Ganges and the northern portion of the Sundarbans depend upon the rain water. As a result these rivers and their branches have flow of sweet water. The Sibsa other rivers in the western part have source of sweet water only in the Ganges and the northern portion of the Sundarbans depends upon the rain water. As a result, the sweet water flow in these rivers decreases during the dry season when there is a massive intrusion of saline water. Moreover the condition of the rivers and canals in the Sundarbans is deteriorating. Shoals are forming and navigability is declining. Rover erosion is taking place at some places.

The forest is within the three administrative districts of Khulna, Satkhira and Bagerhat. Administered by the Forest Department (FD), the area is divided into four forest ranges, namely; Sarankhola, Chandpai, Khulna and Burigoalini. Three patches of the forest in the south have been declared as "Mldlife Sanctuaries". They are Kachikhali-Katka sactuary in the Sarankhola range, Neelkamol at Hiron point in Khulna range and Mandarbari in the Burigoalini range. They have been declared by UNESCO in 1997 as the "World Heritage sires".

The forest is flat and the maximum ground elevation is 3 meter above the mean sea level. The land developed through the process of sedimentation, subsidence and down-wrapping of sediments. The soil is deep alluvium of silty clay loam. It has a tropical humid climate with temperature ranging between 20.4 degree and 51.5 degree Centigrade. The annual rainfall is between 1640 and 2000 mm. The rainfall is strongly seasonal and 85 percent falls during the monsoon, July-October Semi-diurnal type tidal inundation regulates the hydrology of the forest. The four main seasons are pre-monsoon (March-May), monsoon (June-September), post-monsoon (October- November) and dry winter (December-February). The pre-monsoon period is characterized by the southerly winds, high temperature and high rate of evapo-transpiration with occasional heavy thunderstoms and nor western. The forest areas are inundated by tidal water increase which also raises the salinity of river water.

The monsoon ushers in high rainfall, humidity and cloud cover Sediment load and water levels of the rivers also increase. The salinity level is lowered due to the influence of onrushing fresh water from the upstream region. Occasional thunderstorms, cyclones, storm surges and rising salinity levels of river water occur during post-monsoon season, Generally, violent cyclonic storms brew in the Bay from mid- May to mid-June due to north coastal winds, Cyclones also occur in October and early November The dry winter season is characterized by cool, dry and sunny weather with low precipitation.

There is a popular belief that the "Sundarbans" derived its name from the Sundari (Heritiera fomes) trees, a major component of the forest. Legends also have it that the forest received its name from foreign explorers, who termed it as "the jungle of sundry trees" or diverse kind of trees, which finally came to be called the "Sundrybans". There is mother popular folk tale that the very name originated from local word "Samundar" meaning the seas, which later was changed to "Sarnundarbans". 

Floral diversity

The forest supports a diversified flora and fauna. The floristic composition of the Sundarbans encompasses a variety of plants including trees, shrubs, grasses, epiphytes and lianas. Being mostly evergreen, they possess very similar physiological and structural adaptations. As the tidal estuaries deposit vast amount of nutrient rich silt in the deltaic region, they provide an ideal condition in the Sundarbans for the propagation of thick vegetation. Seemingly natural and simple, the succession of mangroves is in reality quite complicated. Each and every species in the Sundarbans has to struggle to grew and survive. Salinity soil conditions, nutrients, weather hazard, sunshine, temperature, Cyclones, tides etc. render the existence of every species difficult in various stages of life cycle.

The uniqueness of the Sundarbans reserve forest lies in its diversity of species. It is interesting to note that tree height is relatively shorter in the west-southern pans and longer in east-northern parts of the forest. Another fascinating feature of the forest is that water of the former region is more saline than that of the latter region. Flora includes 66 species of plants of which 31 are trees. The others are shrubs and climbers. The distribution of the species is not uniform and primarily controlled by the level of salinity and not by the tidal inundation which is fairly uniform, On the basis of salinity level, three zones are recognized : fresh water zone, moderately saline zone and highly saline none. Salinity increases from east to west and north to south.

Altogether 13 forest and four non-forest types of vegetation have been identified of which the Sundari (Heritiera fomes), Gewa (Excoecaria agallocha) and Garan (Ceriopls decandra) are dominant in the fresh water, moderately saline and highly saline zones respectively The Sundari prefers fresh water flushing, drainage predominance and firm higher ground. It is vulnerable to fungal infection and top-dying of the trees makes their survival difficult. Commercially, it is the most sought after tree, comprising about 21% of the forest cover of Bangladesh part of the Sundarbans. Gewa can tolerate high salinity and grows in groves in association with the Sundari, Bain, Hental and Goran bushes. Commercially very important, the Gewa timber is used for paper pulp and in match factories. Garan species of the mangroves grow in the southem Sundarbans, where the tidal influence is high. Being the fuel wood most in demand in the Sundarbans, Garan is also used as a building material.

The other major trees are Keora (Sonneratia apetala), Ora (Scaseolaris), Passur (Xylocarpus mekongensis), Dhundul (Xgranatum), Bain (Avicennia alba), Kankra (Bruguiera gymmotrhiza). Keora and Ora look similar in appearance but Keora being bigger; spreads its branches much more extensively. The Keora is the most graceful and tallest tree in the Sundarbans. Ecologically Keora is the most imponant tree in the mangrove food chain. Birds, bats, rats, monkeys, deer; fishes, insects get their food from its bark, leaves and fruits. Passur is the most praised timber in the Sundarbans as it is used both as building material and furniture timber:

Hental (Phoenix paludosa) is another member of the palm family commonly found throughout the Sundarbans. It is usually a slender straight, small tree which can attain a height of6 meter. The stems of the hental are harvested throughout the year and is sold for making rafters, fence and house-posts. The Golpatta (Nypa fruiticans) grows abundantly along the banks of the Sundarbans rivers a.nd creeks. It is a stemlm palm whose leaves look like Coconut fronds and are mainly used for thatching roofs. Bala (Hibiscus tiliaoeous) is a scrambling woody shrub found along the river banks and is extensively harvested for fuelwood. Garjan and jhanna possess stilt roots, their leaves are

thick and wide. They usually grow along the soggy banks of the creeks. Hogla or Elephant Grass (Typha elphantina) is a pioneer species generally found on riverbanks, estuarine chars (shoals) and along the edge of streams. It is used for making mats and as thatching material for temporary sheds.

 Faunal variety

 Animals have to struggle for life in the Sundarbans due to the forests’ adverse and hostile environment. Almost all the species can tolerate brackish water and subsist on their water intake from food. All the resident species of aquatic mammals, reptiles and amphibians are powerful swimmers and habituated to meeting food requirements partially from aquatic sources. All the terrestrial animals such as birds, reptiles, fishes, plankton etc. are well adapted to the daily periodical and seasonal tidal rhythms. All animals including birds restrict their movement during the high tide. But fishes find the high tide ideal for feeding.

 Sundarbans faunas include 52 species of mammals, 226 species of birds, 35 species reptiles and 8 species of amphibians. Sundarbans is one of the last remaining natural habitat of the Royal Bengal ’Tiger (Panthera tigris tigris). Population density of tigers in the southern Sundarbans grasslands is amazingly high due to the abundance of deer and boar population there. The Sundarbans tigers are more prone to north-south movement and rather adverse to east-west mobility The Sundarbans offer no ideal ground as a tiger habitat. A soft-padded creature like tiger favors walking on dry ground. The Sundarbans tigers have to cross the rivers, creeks and rivulets everyday for survival. They are forced to tread on soggy. muddy terrain and negotiate the piercing roots of various mangrove species. A study suggests that the tiger population of the Sundarbans could be between 800 and 1000.

The other important wild animals in the Sundarbans are the Chital and barking deer; wild boars, rhesus macaque, otters, cats, tree shrews, rats, civets, mongooses, porcupines etc. The Chital or spotted deer (Cervus axis) are reputed to be the most beautiful deer in the world and they have favored the swamp forests of the Sundarbans as their habitat. Compared with other deer species, the Chital is of medium stature. Another deer species found in the north-eastrn Sundarbans of Chandpai and Sarankhola ranges is the barking deer (Muntiacus muntjak), characterised by its doglike barking calls. The Chitals are well distributed throughout the southern sea-board meadows of the Sundarbans where the can graze. Their main fodder in the forest are the leaves and fruits are Keora, new leaves of passur and gewa and various grasses. Large herds of deer may be found in the sea-facing meadows of the Sundarbans in Kochikhali-Katka, Chanmiakhali, Titar Char, jhanpa, Tinkona island. Hiron point and Mandarbaria areas. The barking deer are found only in the northern areas of Chandpai and Nalian forest ranges in the Sundarbans. The wild boar (Sus scrofa), another dominant mammal species of the Sundarbans, is a large and heavily built animal. Being omnivorous, the boar eats a variety of food- roots, tubes, insects, mollusks, carrion, small mammals and even the remains of a tiger kill. Notorious crop-raiders, They are used to attacking and ransacking standing crops on the forest edge.

The Rhesus Macaque (Macaca mulatta) lives ln the Sundarbans in highly organised troops; up to thirty animals co - exist in a band under the leadership of a dominant male. They are equally at home on trees. on the spike roots infested ground as well as the mudbanks. They feed on keora leaves and fruits of telakucha, insects, small lizards, bird eggs, crabs etc. The Rhesus Macaques have developed a mutually effective relationship with the deer in the Sundarbans. A herd of deer can often be seen feeding under a tree inhabited by these monkeys. Both species react to eac other’s alarm calls, warning about the presence of a predator -- a tiger perhaps.

Otter is mainly an amphibian mammal and can be found all over the Sundarbans, but lesser number in the southern areas. The commonest otters of the Sundarbans are the claw-les otters (Aonyx cinerea). The species used widely for fishing in the Sundarbans by the Tarjali fishermen are the smooth Indian otters (Lutra perspicillata). They are bigger; stockier and lighter in colour. It has a streamlined body with shot leg, a thick neck and a long and powerful tail. Like the mongoose, otters sometime stand on their hind legs to see around. Forest otters are active both during day and nlght and they start hunting as the tide goes down. Three species of laser cats may be seen in the Sundarbans, Being highly secretive and exclusively natural creatures, it is difficult to find them. Their coats are well adapted to concealing. All three species are concentrated in the northern forests. The jungle cat (Felis chaus) prefers peripheral forest areas. The leopard cat (Prionailurus bengalensis) ls the most widely distributed animal, compared with the other two. And the fishing cat (Prionailurus viperous) prefers swampy areas of the forest.

 The common tree shrews (Tupala glis) are among the neglected animals of the Sundarbans as they have seldom been recorded. The family Muridae is well represented in the wideness of the Sundarbans. Among other members of the family, musk shrews, bandicoot rats, Indian fleld mouse, house mouse and the common house rats are frequently seen in the area. Civets, mongooses and porcupines are all natural animals and very difficult to find. The presence of Indian porcupine (Hystrix indica) may be felt in Chandpai range areas. The mongooses (Herpestes auropunctatus and Hedwardsi) are found along the forest fringes. The common palm civets (Wverricula indica) can be seen in the eastem forests and the prrsenoe of the large Indian civet (Viverra zibetha) is hardly disoemible inside the forest.

 The brackish water of the Sundarbans estuary supports a number of dolphin species. The presence of the Ganges river dolphin (Platanista gangetica) is most common in the rivers of the Sundarbans. The Crawdad dolphin (Orcaella brevirostris), melon-headed dolphin (Peponocephala electra) and the little porpoise (Neophocaenaphocaenoides) may also be seen without much difficulty. The globular and blunt-headed Crawdad dolphin prefers less saline waters and can be seen in the northern Sundarbans rivers. The massive melon-headed dolphins are well adapted to saline water like the porpoises. Dolphins are seen mostly in the confluence of the major rivers and the creeks. The short-finned pilot whales (Globicephala macrorhynchus) are sometimes found within the Sundarbans.

 In the Sundarbans, saltwater or estuarine crocodiles (Crocodylusporosus) can be seen very often. Once they were abundant ln number in almost every estuary of forest ranges. Sundarbans rivers, especially the chars of the Passur river near Khulna were infested with these reptiles. They were quite fierce. Of late, their population is on the decline, as their egg-laying habitats are being disturbed by collectors of shrimp fries. lt is believed that the total number of crocodiles today may be around 250. In the Sundarbans, one can find some monitor lizards. Three of their species can be found ln the forest: they are the Bengal (Varanus bengalensis), the yellow monitor (Varanus flavaoens) and the ring lizard (Varanus salvator). The ring lizard, dre second largest terrestrial lizard after the Komodo dragon. finds the Sundarbans river estuaries a congenial place for breeding. lt is a voracious eater of birds, bird chicks, snakes, rodents, fishes, etc.

 Among the venomous snakes in the Sundarbans, the King Cobra (Ophiophagus hannah) is considered to be the largest. These are diurnal creatures as their prey species like rattle snakes, young monitor lizards, etc. The King Cobra also preys on small mammals, lizards, bird chicks and other poisonous and non-poisonous snakes. They can move amazingly fast despite their huge size. The forest dwellers dread the King Cobra because of their size and open-mouth charge with hissings. Other cobra species are: Bengal Cobra (Najakauthia), Binocellete Cobra (Naja naja). Bengal cobra is a scary creature and can attack without much provocation. They prefer water habitat and consume mammals, eggs of birds, lizards, amphibians, etc. The Binocellete Cobras are comparatively rare species in the Sundarbans and can be seen in the dry areas of the forest. They carry very potent venom and prey mostly on rodents and amphibians.

 The sluggish vipers are of two species: the chandra bora or the Russel`s viper and the tika bora Thick bodied, the Chandra bora looks more like a young python. The tika bora or spotted tailed green vipers are almost undetectable as they easily camouflage their presence in the green foliage of their habitat. They prey on lizards, insects and bird chicks and eggs. The sea snakes are highly venomous, but due to their small mouth and position of the venom injecting fangs, they seldom bite. Hook-nosed sea snake is the most common sea snake, which is highly venomous. There are a number of non-poisonous snakes including the rock pythons in the Sundarbans.

Among the other reptiles and amphibians, the river terrapin (Batagurbaska) is one of the most commercially exploited estuarine turtles and is listed as an endangered species. The Indian roofed turtle (Kachuga tecta) and the peacock soft-shell turtle (Ttionyx hurum), also listed as endangered, are exploited by the tunle traders. The olive ridley and hawksbill turtles can be seen wading across the shoals of the forest. The exclusive green frogs (Euphlyctis hexadactylus) could be seen in Chandpai area, Other forest amphibians include the skipper frog, bull frog, cricket frog, common toadg and tree frogs seen in the forest and its adjoining areas.

The Sundarbans also provids habitat to a variety of birds. Around 226 species of birds can be found there. Most are resident birds, but some migratory ones can also be seen in the winter season. For more than 100 species of waterfowls, of which some 50 age known to be migratory ones. the Sundarbans provides an important habitat for seasonal migration. The periodically inundated muddy banks of the creeks and the rivers are the ne ting and feeding grounds of these migratory waterfowls. Notable among these are the masked fin foot. white-bellied sea eagle, Pallas’s fish eagle, 8 species of kingfishers, waders, gulls and tems. The loss of nesting sites and availability of food are major factors adversely affecting the distribution, composition and population trends of some of these species.

Though an exact account of fisheries resources of the Sundarbans is non-existent, it is reported that about 120 species of fish are commercially harvested from the area. Dublarchar - an estuarine island in the southern tip of the Sundarbans -- has a sprawling fish industry where seasonal fishermen have developed a fishing village of make-shift houses.

People of the Sundarbans

The Sundarbans with its vast wealth of natural resources always attracted people from different parts of country as well as from abroad for multifarious economic interests. On the one hand there are pirates, poachers and plunderers looting the scaroe resouroes of the forests. On the other; slowly groups of people like Bawalis (woodcutters), Mouals (honey harvesters), grass cutters, fishermen and mollusk shell collectors converged in the area for exploiting the forest resources on which their livelihood depends. These latter sections of people are the forest dwellers -- courageous, bold and adventurers. They are aware of the hazards of the forest life. Living in the forests for many generations, they have by now developed a coping strategy for survival in a hostile and inhospitable environment.

Traditionally these forest dwellers possess the indigenous instinct and knowledge of their forefathers. They face various natural calamities like tidal surges, cyclones, rains, scorching heat, and humidity they have to tread between the trails of poisonous snakes, wild boars, crocodiles, man-eating tigers and the pirates. They leave behind their families for months and lead a life of great insecurity and loneliness. It can be said drat lives of these forest dwellers are regulated by tidal rhythm and the movement of the moon. The Bawalis, Mouals, grass cutters, fishermen have to know about the tidal movement. Even the predators and the preys in the jungle are aware of tidal timings. The moon plays an important role in the forests. Specially for the fishermen, Vara Katal or Vara Gone, meaning moonlit nights bring hope and fortune, as they expect a good catch this time of the month. 0n the other hand, Mora Katal is a period of dark nights that bring grief and miseries for them.

Bawalis, the wood cutters, receive seasonal permits from the local forest offices, which allow them to harvest mainly the Gewa trees for paper and pulp industry. Although they move in a group, they take high risk as they enter the forests and live in make-shift houses for months in isolation. Mouals are seasonal professionals who work for three to four months inside the forest during the flowering season. Honey collection season starts on the first day of April with assembly prayers at Burigoalini range office. Permits are issued by the forest officials for the particular season. Most of the honey producing plants grows abundantly in the Burigoalini range areas. Under the leadership of a Shaindar or Bahardar, a group of Mouals, usually in odd numbers goes to Mahal, the site for honey collection for a period of three months. The Mouals perform the most dangerous profession. Virtually, they have to traverse every inch of the forest land through the apparently impenetrable mud and slush. They walk bare-footed over the shula-ridden jungle floors and swim across the creeks and canals in high risk. In a team, there is a Gunin or a spiritual guide to provide divine blessing. Every year a few of these Mouals are killed by tigers.

The Jalias or the fishermen come to the Sundarbans from the neighboring districts. Offshore fishermen are almost strangers having little interaction with the forest people, while the onshore fishermen are part of the forest dwellers. One-third area of the Sundarbans is water. Hundreds of Water channels cross-cross the landmass and constitute an ideal habitat for brackish water fishes. Tire fishermen constitute the largest forest dwelling community about 48 percent of the total forest dwellers. Of late, due to introduction of shrimp farming, shrimp fry collection in the rivers and creeks of the Sundarbans is on the rise causing destruction of fish diversity as they only collect the shrimp fries and throw away all other species. The forest dwellers pay homage to certain gods and deities whom they thought to be their saviors and protectors. The popularly worshipped are the Banbibi, Gazi Shaheb, Dakshin Ray, Pir Badar, etc. These days, almost all the forest dwellers, irrespective of their religious or communal beliefs, seem to rely much more on a piece of cloth, a triangular red cloth blessed by the "Pir Shaheb" of Noapara, which they hoist atop the mast of their boat with great respect.

Depletion d biodiversity

The biodiversity of the Sundarbans has been under threat for various reasons. There has been increasing conversion of the forest land for agriculture, mainly for paddy and shrimp farming and for human habitation. The forest’s bio-diversity is also threatened by unabated poaching hunting, illegal felling of trees, diseases, unplanned and over extraction of recourses, insufficient conservation effort, deterioration of law and order situation, corrupt practices of the forest officials and unscrupulous traders etc. Poverty population pressure and encroachment by the forest/local people are blamed for the depletion of bio-diversity in the Sundarbans. Contrary to this customary belief, plundering and exploitation of forest recourses by the poachers and dacoits in connivance with the corrupt forest officials are said to be the main causes of forest loss in the Sundarbans. Recurrent natural calamities like storms, cyclones and tornadoes pose a big threat to tall slender trees, which act as a barrier against the cyclones and tidal surges originating in the sea. More than a dozen of Cyclones have hit the Sundarbans during the last decade. A disastrous cyclone at Dublar Char in 1988 ,15 November 2007and  25 may 2009 devastated the forests and the fishermen’s villages.

Besides these anthropogenic activities and natural calamities, some ecological changes like increase in salinity, outbreak of diseases like "top dying" of the Sundari trees pose a serious threat to rich biodiversity of the Sundarbans. Such diseases are taking a heavy toll of the wood lots in the Sundarbans. Actual cause of the disease is not yet known. Diversion of the natural courses of rivers, construction of embankments, dams and bridges in the upstream as well as decreased flow of fresh water in the rivers resulted in the increase in salinity level and over-silting in many places and caused subsequent changes in the mangrove ecosystem. Increased salinity and siltation within the forest area may hinder the biological functions of the breathing roots and are supposed to the major causes of top dying of the trees. Possibility of fungus pathogens can not be overlooked. In the Sundarbans, for bringing noncommercial cover areas under tree cover in different areas of Chandpai, Sarankhola and Kulna forest ranges, plantation of exotic species, like Acacia nilotica, Alibizia procera have taken place. Though at a limited scale, many other exotic species have been introduced in the Sundarbans mangrove ecosystems, particularly in areas around the forest offices. It is apprehended that these exotic species may pose a threat to the native variety of mangrove species.

Sea-level rise

Another looming threat to the Sundarbans -- the world‘s largest remaining mangrove forest -- is the much talked about sea-level rise that scientists have already predicted. According to a conservative estimate, the sea-level rise that is expected to inundate many a island nations as well as low-lying coastal regions across the world – thanks to the global warming and green house effects, it is now widely believed by experts that sea-level rise by one meter, expected to take place by the current century, will devour the whole of me Sundarbans. That is another major concern for our great natural heritage called the Sundarbans.

Following reasons have been identified as major threats to die bio diversity of the Sundarbans:

O             Population pressure, expansion of agricultural land construction of houses, roads, embankments, bridges, etc;

O             Faulty shrimp fry collection and conversion of forest lands into shrimp farming;

O             Unscrupulous harvesting of forest resources and insufficient measures to regenerate the resources;

O             indiscriminate use of chemical fertilizers and insecticides in croplands and adoption of unplanned agricultural practices resulting in low productivity of the forest;

O             Introduction of exotic species of trees that threaten the native mangrove species;

O             Lack of appropriate policies for proper management and training of forest officials working in the wildlife sanctuary/protected areas;

O             Activities of the pirates, poachers, plunderers of resources in the Sundarbans;

O             Uncontrolled diseases causing a havoc, mainly on the Sundari trees;

O             Unregulated testing and exploration activities by the international Oil Companies in the Sundarbans; and

O             Apprehended sea level rise due to global warming, which would permanently inundate coastal low-lying areas with saline water.

Conclusions

Tire World Heritage Site of Bangladesh, the Sundarbans, is indeed a treasure-trove of bio-diversity because of its wide spectrum of flora and fauna, its range of ecosystem, species and other forest resources have supported and contributed to the existence, adaptation and well-being of the forest dwellers in particular and people in the periphery in general. Indigenous knowledge and practices of the local people – the forest dwellers, acquired through many generations, in fact helped in the conservation and management of the forests. They are no "encroachers". The pirates, poachers, corrupt officials and unscrupulous forest traders are in fact the plunderers of the forests. They are the infiltrators to be dealt with strictly Rule of law has to be established in the forests with proper forest conservation policies and plans, Forest officials have to be properly trained in modem conservation practices. Forest resources are to be considered from conservation point of view and taken as commercial products. The sanctuaries have to be strictly managed by enforcing laws and regulations. Forest users including the tourists must be made aware of the sensitivities of the nature and wildlife within the forests. Let us not forget the fact that the mangrove forests of the Sundarbans are a delicate ecosystem that must be dealt with proper attention and care.