Ojana kiso kotha: Robot can leap from water’s surface August 1, 2015 11:56 am

Saturday, August 1, 2015

Robot can leap from water’s surface August 1, 2015 11:56 am

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Scientists have developed a tiny robot – based on the water strider insect – that can jump on water.

The robotic version uses the same forces to jump as the water strider – pushing off without breaking the surface.

It takes off with a downward force that never exceeds the surface tension of water – the force that “glues” surface water molecules together.

The South Korea and US team’s advance is reported in the journal Science.

Lead researchers Prof Ho-Young Kim and Prof Kyu-Jin Cho, from Seoul National University, used water striders from their local pond in the study.

“To explore [their] amazing semi-aquatic motility, we collected [the insects] and recorded them jumping on water in the laboratory with high-speed cameras,” the scientists said.

“[These imaging experiments] revealed that the insect rises upward while pushing the water surface downward and closing four of its legs inward.”

So the team set out to build that motion into the design of their robot.

Each robot’s 2cm (0.8in) body is made of layers of thin material folded into a vee-shape, with a spring running across its length.

When powered up for a jump, the spring releases, but slowly, dragging the ends of robot’s body and its 5cm insect-like legs downward with gradually increasing force to the limit the water surface will withstand.

The robots – and the insects – also rotate their legs inward “to maximise the interaction time between the legs and the water”.

The researchers envisage an environmental application for their robotic water strider – monitoring pollution in waterways.

But they added their goal had been not to commercialise their miniature robot, but to explore “a new possibility [for] a robot’s aquatic mobility”.

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Ojana kiso kotha

undarban:World largest mangrove forestGeneral Description Sundarban is the biggest mangrove forest in the world. Sundarban is in South West part of Bangladesh, in the district of greater Khulna. India shares a bit of the forest with Bangladesh. The total area is about 38,000 square kilo meters. Sundarban is a large block of littoral forests. The beauty lies in its unique natural surrounding. The Sundarbans are a part of the world's largest delta formed by the rivers Ganges,Brahmaputra and Meghna. Thousands of meandering streams, creeks, rivers and estuaries have enhanced its charm. For miles and miles, the lofty treetops form an unbroken canopy, while nearer the ground, works of high and ebb-tide marked on the soil and tree trunks and the many varieties of the natural mangrove forest have much to offer to an inquisitive visitor. Sundarban is the natural habitat of the world’s famous Royal Bengal Tiger, spotted deer, crocodiles, jungle fowl, wild boar, lizards and many more. Migratory flock ofSiberian ducks flying over thousands of sail boats loaded with timber, Golpata, fuel wood, honey, shell and fish further add to the serene natural beauty of the Sundarban. Figure: map of Sundarban (For details) In general, the northern boundary and new depositions are characterized by Baen (Avicennia marina , A. alba, A. officinalis ) flanked by foreshore grassland of Oryza coarctata (Dhani grass). Baen is gradually replaced by Gewa (Excoecaria agallocha) and then Goran (Ceriops spp.). The southern and eastern associates include Garjan (Rhizophora spp.), Kankra (Bruguiera spp.), and few patches of Sundari (Heritiera fomes) . Hental (Phoenix spp.) forest exists in relatively high land and compact soil. Dhundul (Xylocarpus granatum), Passur (Xylocarpus mekongensis) and Nipa fruticans (Golpata) palm swamps are extremely limited. Location and history sohanaakter.bloggspot.com The Sundarban Reserved Forest (SRF), occupying an area of around 6,017 square kilometres or 600,000 hectares, represents 51 percent of the total reserved forest area of Bangladesh and as such forms a rich and diverse ecosystem with potential for sustainable natural resource management. Man has exploited the Sundarban for centuries but the forest was not given Reserve status by the Forestry Department until 1875. managed the forest and other natural resources of the SRF through adherence to management plans which it prepares at regular intervals.Early management simply concentrated on revenue collection and the enforcement of felling rules to reduce overcutting, particularly in the eastern portion. The first real professional forest management planning was introduced in the SRF in the early 1900s with the introduction of the Curtis Working Plan. However, more recently forest resource management has shifted to increase emphasis upon environmental and socio-economic issues. The following table presents the fractions represented by forest and other land types in the Sundarban. Famous spots The main tourist point is Hiron Point (Nilkamal) for watching tiger, deer, monkey, crocodiles, birds and natural beauty. Katka is for watching deer, tiger, crocodiles, varieties of birds and monkey. Morning and evening symphony of wild fowls. Vast expanse of grassy meadows running from Katka to Kachikhali (Tiger Point) provide opportunities for wild tracking. Tin Kona Island for tiger and deer. Dublar Char(Island) for fishermen. It is a beautiful island where herds of spotted deer are often seen to graze. Here land and water meet in many novel fashions, Wildlife presents many a spectacle. No wonder, you may come across a Royal Bengal Tiger swimming across the streams or the crocodiles basking on the river banks. With the approach of the evening herds of deer make for the darkling glades where boisterous monkeys shower Keora leaves from above for sumptuous meal for the former. For the botanist, the love of nature, the poet and the painter this land provides a variety of wonder for which they all crave. Areas in Sundarban Type Area (km2) Percent Forest area 3997 66 Sandbars, grass, bare ground 115 2 Rivers 1905 32 Total SRF (of which 1397 km2 represented by 3 wildlife sanctuaries) 6017 100 Areas by species Species Area (km2) Percent (%) Production forest Wildlife sanctuary Total Sundri 1801 170 1905 46 Gewa 1056 262 1318 32 Goran 303 345 648 16 Keora 59 24 83 2 Passur 28 0 28 1 Baen 10 2 12 0 Tree plantations 2 0 2 0 Grass, bare ground 46 23 69 2 Sandbars 27 19 46 1 Total 3267 845 4112 100 Fauna of Sundarban The Sundarbans hosts a large variety of animals. It is the last stronghold of thebengal tiger (Panthera tigris). Within the forest habitats there are about 50 species of mammals, about 320 species of inland and migratory birds, about 50 species of reptiles, 8 species of amphibians, about 400 species of fish Besides the spectacular Royal Bengal Tiger, the other notable mammalian fauna are Spotted deer (Cervus axis), Barking deer (Muntiacus muntjak), Rhesus macaque (Macaca mulatta), Jungle cat (Felis chaus), Leopard cat (Prionailurus bengalensis), the Indian porcupine (Hystrix indica), Otter (Lutra perspicillata), and wild boar (Sus scrofa). deer and wild boar constitute the main prey for the tiger. Some species including the Bengal tiger are endangered. Important Animal Species. Mammals are 49, Birds are 314, Reptiles are 50, Amphibious are 8. Endangered Species. Mammals are 10, Birds are 11, Reptiles are 16, Amphibious are 1. Aproximate (imagine) numbers of the important Species. The Royal Bengal tigers are: 1000-1200, Deers are: 3, 50, 000-4, 00, 0000, Monkeys are: 90,000-1, 40, 000, Crocodiles are : 500-1000. The ecological diversity of the Sundarbans supports a large variety of birds. Among the total number of species recorded, most are resident. Over 50 species are known to be migratory and are mostly represented by the waterfowls. The egrets, storks, herons, bitterns, sandpipers, curlew, and numerous other waders are seen along the muddy banks. There are many species of gulls and terns, especially along the seacoast and the larger waterways. Accipitridae (kites, eagles, vulture, harrier etc) is represented by about 22 species. Nine species of kingfishers are available in the forest. The rich avifaunas of the forest include species of woodpeckers, barbets, owls, bee-eaters, bulbul, shrikes, drongos, starlings, mynas, babblers, thrush, oriole, flycatchers, and many others. Of about 50 species of reptiles the largest member in the Sundarbans is the Estuarine crocodile (Crocodylus porosus), some of which may attain a length of about seven metres. Although once they were abundant in this mangrove habitat, their total number is now estimated to be around 250. Species of lizards, including the Monitor Lizards Varanus, turtles, and snakes are well-represented. Among the snakes, the King Cobra (Ophiophagus hannah), Russell's Viper (Vipera russellii), Rock python (Python molurus), Banded Krait (Bungarus fasciatus) and several species of sea snakes are notable.Only eight species of amphibians have been reported from the Sundarbans. The green frog (Euphlyctis hexadactylus) is mostly observed in Chandpai area of the mangrove forest. The other forest amphibians include the Skipper frog (E. cyanophlyctis), Cricket frog (Limnonectes limnocharis), Tree frog (Polypedates maculatus), and the common toad. The Sundarbans supports nearly 400 species of fishes in its varied aquatic habitats; these include both the pelagic and demersal fishes. Many species use these habitats as nursery grounds. No aquaculture or fish farming is allowed in the Sundarbans. The Forest Department controls the fish catch from the area. Among the invertebrates some molluscs and crustaceans constitute important fisheries resources. About 20 species of shrimps, 8 species of lobsters, 7 species of crabs, several species of gastropods, and 6 species of pelecypods have been reported from the Sundarbans. Among the shrimps Penaeus monodon andMetapenaeus monoceros and the mud crab Scylla serrata are commercially important. Insects are varied, the most important being the honeybee Apis dorsata. Locally known as 'Mouals', the professional bee collectors gather honey for three to four months during the flowering season taking permission from the Forest Department. The forest is very rich in its spider fauna (Araneae). Nearly 300 species under 22 families have been recorded as Wildlife - Sundarban Studies and Survey of Sundarban (1) Tiger Although the tiger population is the largest in the world, it numbers only several hundred individuals and it is isolated from other populations. Incidental mortality due to disease, sudden prey decrease or pollution constitutes, therefore, a serious risk for the survival of the Sundarban tiger. Apart from that, the interaction with humans in the area, particularly the killing of humans by tiger, complicates the management of the area. Careful scientifically based management is therefore required for appropriate conservation of this species. Research regarding tiger will focus on population size and dynamics, distribution and tiger - human conflicts.To know details click here (2) Deer Deer is the most important herbivore in terms of number and biomass (1150 kg/km2) and deer grazing and browsing is a main factor in the structure of the vegetation cover. Moreover, deer is the main prey of the Sundarban tiger. Deer research will focus therefore on: the distribution, habitat utilization, food availability, drinking water dependency, the impact of grazing/browsing, and population dynamics.To know more, click here (3) Other surveys and studies Other surveys and studies that will be carried out by SBCP include marine mammals, birds, crocodiles and turtles, providing essential information for management planning and monitoring. Additional studies on hunting and vegetation will be carried out. Non-Wood Forest Products - Sundarban Non-wood forest products (NWFP) from the Sundarban Reserved Forest (SRF) play a major role in the lives of hundreds of thousands of people who live near its boundaries. These products are harvested for both subsistence and commercial purposes and represent an important source of income for land-poor families, especially during the winter months of food deficit. Figure: Picture of Golpata Golpata (Nypa fruticans) is a regal palm that grows in monotypic stands along the banks of the numerous rivers and canals that bisect the dense mangrove forests of the Sundarban. It is by far the most important NWFP in the region. Every year, from December to May, thousands of "bawalis" (traditional forest users) collect an average of 60,000 metric tons of fronds from throughout the SRF. This number, however, could be a fraction of the actual amount harvested. The fronds are sold at several trade depots in the adjoining districts and used as a traditional roofing material throughout the country. The fruits are used to make a local wine.Other species are important as well. Hantal (Phoenix paludosa) is a palm used in construction as rafters and framework. It is not as popular as golpata and is harvested in much smaller quantities at an average of 3000 metric tons per year. An average of 3000 metric tons of a variety of grasses are annually harvested from the SRF as well. This includes malia (Cyperus javanicus), nal (Eriochlea procera) and ulu (Imperata cylindrica). Malia is used for making mats, nal for making baskets and fences, and ulu for thatch. Goals/Approach of the NWFP Component Our initial assessment indicates that there appears to be no outstanding sustainability issues for NWFP’s in the SRF, although some stands/populations have reportedly been degraded from intensive and/or improper harvesting. From a biodiversity conservation perspective, it is the secondary impacts of NWFP harvesting that represent the greater threat. Simply having more people in the forest for protracted periods of time can be disruptive and offers opportunities for poaching and other types of destructive behavior. Large-scale harvesting can also lead to bank erosion and habitat degradation of fish, amphibians, crustaceans and other riparian fauna. At present, however, we do not completely understand the role of NWFP’s in the ecology of the Sundarban. The crucial issue is that there are no viable income alternatives for the hundreds of thousands of poor people who live around the SRF and are almost totally dependent on its resources, including NWFP’s. Thus, the long-term goal of the NWFP component echoes that of SBCP: to improve the livelihoods of impoverished users by introducing viable economic activities outside of the SRF. In doing so, it is hoped that the overall pressure on the SRF will be reduced and the forest, wildlife and environmental services it provides will be preserved. Knowing that this can take several years - in fact, decades - to accomplish, the short-term strategy is to: · Evaluate the effectiveness of current Forest Department management practices and recommend changes, if necessary. · Identify value-addition opportunities for species currently harvested on a sustainable basis in order to bring greater economic benefits to the impoverished communities in the area. · Identify and restore degraded stands of important NWFP’s inside the SRF. · Search for areas outside the SRF to produce golpata and other non-wood species in a more intensive and accessible fashion through community and private forestry programs. · Investigate viable income and livelihood alternatives based outside the SRF for those directly engaged in NWFP harvesting. To know details about NWFP of Sundarban , (click here) Biodiversity of Sundarban The Sundarban is the largest contiguous block of mangrove forest remaining in the present day world and a large unique mangrove ecosystem, recognized as a site of national and international importance for conservation of biodiversity. This forest is an independent "Biome", enriched with different biodiversities along with a great variety of wild life. Besides dolphins and porpoises, Sundarban mangroves are habitats of many rare and endangered animals (Batagur baska, Pelochelys bibroni, Chelonia mydas), especially it is the unique natural habitat of the world famous Royal Bengal Tiger (Panthera tigris), spectacular spotted deer (Axix axix), jungle fowl (Gallus sp.) and rhesus monkey (Macaca mulata). The forest has a unique biota comprising 334 species of plants, 49 species of mammals, as many as 400 species of fish, 315 species of birds and 53 species of reptiles; besides numerous species of phytoplankton, fungi, bacteria, zooplankton, benthic invertebrates, mollusks, reptiles, amphibian and mammals. Species composition and community structure varies east to west, and along the hydrological and salinity gradients. Ecologically, the forest is particularly important as a barrier to cyclones, tidal upsurges, etc. It is also acting as a huge sink of unlimited capacity for absorbing CO2 and other pollutants from air and water which makes the surrounding environment free from pollution. The mangroves of the Sundarban are unique when compared to non-deltaic coastal mangrove forest. Unlike the latter, the Rhizophoraceaeare of only minor importance and the prime species are sundri (Heritiera fames), from which the Sundarban takes its name, and gewaExcoecaria agallocha. The reason for this difference is the large freshwater influence in the north-eastern part and the elevated level of the ground surface. The Sundarban can be classified as moist tropical seral forest, comprising a mosaic of beach forest and tidal forest. Of the latter, there are four types: low mangrove forests, tree mangrove forests, salt-water Heritiera forests and freshwater Heritiera forests. Sundarban West occurs within the salt-water zone, which supports sparse Ecoecaria agallocha, a dense understory of Ceriops, and dense patches of hantal palm Phoenixpaludosa on drier soils. Dhundal and passur (Xylocalpus spp), and Bruguiera occur sporadically throughout the area. Sundri and gewa cover most of the Sundarban but Oryza coarctata, Nypa fruticans and Imperata cylindrica are prevalent on mud flats. Large stands of keora (Sonneratia apetala) are found on newly accreted mud banks and provide important wildlife habitat. The Sundarban is the only remaining habitat in the lower Bengal Basin for a variety of fauna1 species. The presence of 49 mammal species has been documented. Of these, no less than five spectacular species, namely Javan rhinoceros Rhinoceros sondaicus (CR), water buffaloBubalus bubalis (EN), swamp deer Cervus duvauceli (VU), gaur Bosfrontalis (VU) and probably hog deer Axis porcinus (LR) have become locally extirpated since the beginning of this century. The Sundarbans of Bangladesh and India support one of the largest populations of tiger Panthera tigris (EN), with an estimated approximately 700 (2004). These tigers are well-known for the substantial number of people they kill; estimates range from twenty and eighty people per year. They are the only man-eating tigers left in the world, though they are not the only tigers who live in close proximity to humans. The varied and colorful bird-life to be seen along its waterways is one of the Sundarbans’ greatest attractions. A total 315 species have been recorded, including about 95 species of waterfowl and 38 species of raptors. Among the many which may be readily seen by the visitor are no less than nine species of kingfisher, including brown-winged and stork-billed kingfishers, Pelargopsis amauropterus (NT) and P. capensis, respectively; the magnificent white-bellied sea-eagle Haliaeetus Zeucogaster which, at a density of one individual per 53. l km of waterways, is quite common; also the much rarer grey-headed fish eagle Zchthyophaga ichthyaetus (NT), Pallas’s fish-eagle Haliaeetus Zeucoryphus and several other raptors. Herons, egrets, storks, sandpipers, whimbrel, curlew and numerous other waders are to be seen along the muddy banks and on the chars or sandbanks which become exposed during the dry season. There are many species of gulls and terns, especially along the coast and the larger waterways. Apart from those species particularly associated with the sea and wetlands, there is also a considerable variety of forest birds such as woodpeckers, barbets, shrikes, drongos, mynahs, minivets, babblers and many others. Some 53 reptile species and eight of amphibians have been recorded and of these, mugger Crocodyluspalustris (VU) is now extinct, probably as a result of past over-exploitation, although it still occurs in at least one location nearby. Estuarine crocodile C. porosus still survives but its numbers have been greatly depleted through hunting and trapping for skins. Four species of marine turtle have been recorded from the area, olive ridley Lepidochelys olivacea (EN) being the most abundant. Green turtle Chelonia mydas (EN) is rare due to excessive fishing, while loggerhead Caretta caretta (EN) and hawksbill Eretmochelys imbricata (CR) are not common although there have been some reported on the beaches (Hussain and Acharya, 1994). River terrapin Batagur baska (EN) is also present. The eighteen recorded snake species include king cobra Ophiophagus hannah and spectacled cobra Naja naja, three vipers and six sea-snakes(S alter, 1984). Over 120 species of fish are reported to be commonly caught by commercial fishermen in the Sundarban. Freshwater species are alarmingly decreased day by day. Crustacea account for by far the largest proportion of animal biomass, with an estimated 40 million kilograms of fiddler crabs and 100 million kilograms of mud crabs (Hendrichs, 1975). The nutrient-rich waters of the Sundarban also yield a considerable harvest of shrimps, prawns and lobsters. The area supports a varied insect population including large numbers of ants, honey-bees etc. and honey and beeswax are economically very important products. The insect life of the Sundarban has been little studied. Protection Status of the Sundarban The Sundarban Forest covers 10,000 km2 of mangrove forest west of the main outflow of the Ganges, Brahmaputra and Malancha rivers. Around 60 % of this area is part of Bangladesh territory and entirely gazetted Forest Reserve, which was a phased process starting in 1885. The remaining 40 % is part of India. Within the Sundarban Reserved Forest (SRF). 3 Wildlife Sanctuaries were established in 1974 under the Bangladesh Wildlife Act of the same year. Around the SRF the Sundarban Biodiversity Conservation Project has identified a so-called "Impact Zone" where most of the direct users of the forest are residing. Threats The SRF is surrounded by a very densely populated area, therefore human pressure is important. Around 1.2 million local users reside seasonally in the area for fishing and other resource use activities. Commercial hunting was a problem mainly before the 1970s and this resulted particularly in a serious depletion of the crocodile populations and to a lesser extent to the deer population. Although the protection has improved significantly in the last decades, illegal hunting is still occurring on an incidental basis and fishery is having an adverse impact on the populations of the remaining turtle and crocodile populations as these animals drown frequently in fishing nets. Due to natural processes the role of the Sundarban to discharge the water of the Ganges and Brahmaputra catchment is decreasing as main waterways are shifting eastwards. As a result the salinity of the Sundarban is increasing, particularly in the western region. Further, the total annual discharge is decreasing due to intensifying land use (dams, irrigation) upstream. The role of this change is not yet clear, but is evident that it will influence wildlife populations and vegetation in the long term. However, the main threat today may come from outside the area in the form of pollution. On the northern edge of the area, Mongla, Bangladesh’ second largest port, is situated. This port and its associated marine traffic is a frequent source of oil spills and there is a permanent risk of accidents with chemicals. Moreover, toxic products (pesticides, etc.) enter the system due to upstream pollution in the huge Ganges catchment. Pollution may be a direct source of mortality, but it may also reduce the health, increasing the mortality rate on the long term. Many products such as pesticides have also been proved to reduce the reproductivity (birth rate) in animal populations. A future threat is the exploitation of mineral gas, which is abundant in the underground of the Sundarban. Some species extinct during the last century are javan rhinoceros (Rhinoceros sondaicus),water buffalo (Bubalus bubalis),swamp deer (Cervus duvauceli), gaur (Bos gaurus),hog deer (Axis porcinus) Ecology and management of Sundarban “If there is no mangrove forest, then the sea will have no meaning. It is like having a tree without roots; …mangroves are the roots of the sea." - A Fisherman on the coast of the Andaman Sea. The Sundarban, covering about one million ha in the delta of the rivers Ganga, Brahmaputra and Meghna at the point where it merges with the Bay of Bengal, is the single largest block of tidal halophytic mangrove forest in the world shared between Bangladesh (62%) and India (38%), which supports a large, biodiversity-rich unique ecosystem. With its array of trees and wildlife the forest is a showpiece of natural history. It is also a center of economic activities, such as extraction of timber, fishing and collection of honey. The area of Sundarban experiences a subtropical monsoonal climate with an annual rainfall of 1600-1800 mm and severe cyclonic storms. Enormous amount of sediments carried by the three rivers contribute to its expansion and dynamics. Salinity gradients change over a wide range of spatial and temporal scales. Interestingly, the Bangladesh and Indian portion of the forest are listed in the UNESCO world heritage list separately as the Sundarban i.e. the “beautiful forest” and Sundarban National Park respectively, though they are simply parts of the same forest. The Sundarban is intersected by a complex network of tidal waterways, mudflats and small islands of salt-tolerant mangrove forests, and presents an excellent example of ongoing ecological processes. The area is known for its wide range of flora and fauna. The most famous among these are the men eating Royal Bengal Tigers, but numerous species of birds, spotted deer, crocodiles and snakes also inhabit it. The mangroves have been extensively exploited over centuries for timber, fish and prawns, honey, fodder, or converted for paddy and aquaculture and now it faces the serious challenges for its existence. Javan rhino, wild buffalo, hog deer, and barking deer are already extinct from the area. While conservation efforts have focused on wildlife, particularly tiger, through creation of several sanctuaries and a biosphere reserve, reduced freshwater inflows are a serious threat as salinity is rising. Heritiera fomes(from which Sundarban derives its name), Nypa fruticans andPhoenix paludosa are declining rapidly. Other threats to biodiversity come from the growing human population, pollution, and a rise in sea level. The Mangroves and Sundarban Mangroves are intertidal forested wetlands confined to the tropical and subtropical regions. The total global area of the mangroves is estimated at only 18.1 million ha, against over 570 million ha of freshwater wetlands including peat lands globally. Although mangroves have been exploited for many centuries, its ecosystems are now the most threatened one by the global climate changes, particularly the sea level rise. More than 41 % of the world’s mangroves occur in South and Southeast Asia of which Indonesia alone accounts for 23 %. A further 20 % of the total mangrove area lies in Brazil, Australia and Nigeria. While practically all mangroves occur in small patches that develop in deltaic habitats, the mangroves in the Ganga-Brahmaputra-Meghna Delta, shared between India and Bangladesh, are the only contiguous and largest coastal wetland system in the world. Exploration of the Sundarban mangroves dates back to the 16th century. It may be noted here that since 1947 the Sundarban mangroves are divided between India and Bangladesh (formerly East Pakistan), as Sundarban in Bangladesh and as Sundarban National Park in India, and the two parts differ considerably in the nature and extent of investigations, conservation and management. They also differ substantially in the level of human exploitation over more than a century. This makes it difficult to integrate the information of the entire Sundarban. The mangrove-dominated Ganges delta, the Sundarban, named after the dominant species Sundri (beautiful) tree (Heritiera fomes-a mangrove tree that requires freshwater), is a complex ecosystem of mangrove forests in the world. Shared between two neighboring countries, Bangladesh and India, the larger part (62%) is situated in the southwest corner of Bangladesh located between 21°30 َ N to 22°30 َ N and longitude 89° E to 90° E. To the south the forest meets the Bay of Bengal; to the east it is bordered by the Baleswar River, to the west by the Sundarban National Park of India and to the north there is a sharp interface with intensively cultivated land. The forest consists of about 200 islands, separated by about 400 interconnected tidal rivers, creeks and canals. The total area of the Sundarban Reserved Forest (SRF) is 6,017 km2 out of which 4,143 km2 is land area and 1,874 km2 is water area comprising rivers and tidal waterways. This area is approximately half the size of the area of mangrove that existed 200 years ago, the other half being cleared and converted to agricultural land. Rivers in the Sundarban are meeting places of salt water and freshwater. Thus, it is a region of transition between the freshwater of the rivers originating from the Ganges and the saline water of the Bay of Bengal. The geological setting of the Sundarban ecosystem is a delta of interconnecting large rivers: the Ganges; the Bramaputra, and the Meghna. The sediment is of recent origin, consisting of alluvium washed down from the Himalayas deposited over the older sediments carried by the three rivers. The forest floor is 0.91m to 2.11m above mean sea level. The pH ranges widely from 5.3 to 8.0. Although the Sundarbans 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. Its ecosystem is characterized by a very dynamic environment due to the effect of tide, flooding, salinity and even the cyclones. 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 Sundarban are fairly equable than those of the adjacent land areas. The average annual maximum and minimum temperatures vary between 30º and 21ºC. High temperatures occur from mid-March to mid-June and low in December and January. The mean maximum temperature for the hottest months has been recorded as 32.4ºC at Patuakhali, in the east of the Sundarban. 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. Ecosystem Management, Forest Conservation & Sustainability The Sundarban is the world's largest remaining contiguous, biodiversity-rich mangrove ecosystem featuring habitats for fish, shrimp, birds, and other wildlife, including the Bengal tiger. The forest also has immense protective and productive functions. Constituting 51% of the total reserved forest estate of Bangladesh it contributes about 41% of total forest revenue and accounts for about 45% of all timber and fuel wood output of the country (FAO 1995). A number of industries (e.g. newsprint mill, match factory, hardboard, boat building, furniture making) are based on the raw material obtained from the Sundarbans ecosystem. Various non-timber forest products and plantations help generate considerable employment and income generation opportunities for at least half a million poor coastal population. Besides production functions of the forest, it provides natural protection to life and properties of the coastal population in cyclone prone Bangladesh. The Sundarban mangrove forest is most likely to be changed directly or indirectly by human activities and a priority question in conservation planning is what to expect from the Sundarban in the future. It is very difficult or almost impossible to rehabilitate a mangrove forest to its original state once it is destroyed severely or completely. This is because the changes that the ecosystem undergoes and the conditions under which the natural mangrove vegetation flourish are hardly likely to restore. However, like some other countries, some efforts and strategies have been made in Bangladesh to protect the Sundarban, the most important area left for the long-term survival of many forms of wildlife because the area is large enough to support a large effective population size. The Sundarban mangrove forest has a distinct forest management history. The area was mapped as early as 1764, soon after proprietary rights were obtained by the East India Company in 1757. The first Forest Management Division with jurisdiction over the Sundarban was established in 1869 and the first management plan was introduced in 1892. Conservation of the Sundarban mangrove is supposed to have started with its declaration as a reserve forest, under the Forest Act in 1878. In 1977, Bangladesh created three wildlife sanctuaries: the Sundarban West (71,502 ha), Sundarban East (31,226 ha); and Sundarban South (36,970 ha), protecting about 23.5 % of the remaining Sundarban under the Bangladesh Wildlife (Preservation) (Amendment) Act, 1974. These sanctuaries (IUCN, 1997) lay on disjunctive deltaic islands in the Sundarban Forest Division of Khulna District, close to the border with India and just west of the main outflow of the Ganges, Brahmaputra and Meghna rivers. In 1987, the Sundarban National Park in India, and in 1997, parts of the Sundarban in Bangladesh, was inscribed on the World Heritage list (IUCN, 1997) and thereafter it receives more attention. In view to maintain the ecological balance and to develop the resource for sustainable utilization, the Government of Bangladesh has formulated and established different management policies and action plans. At the same time, various non-government organizations (NGOs) and private organizations have engaged themselves in research, management and development processes. The Government also provides institutional, infrastructural and legal support to encourage participation of such organizations. Moreover, International organizations such as CIDA, AIDAB, USAID, JSPS, UNDP, UNESCO, FAO, ADB, and World Bank have sponsored research programs on mangrove ecosystems and various development activities. Besides, many experts, however, are hoping that the Sundarbans Biodiversity Conservation Project (1998) would help to reverse the negative trends at the forest in a great extent. Although mangroves are exploited for a diverse array of purposes, the practice of afforestation in the mangrove areas is almost recent. Information regarding the nursery raising and planting techniques for mangrove species still are not adequate and complete. However, to some extent, afforestation with mangrove species have been standardized and are implemented with varying degrees of success in sites which have not been too badly degraded. The program of afforestation in Bangladesh was initiated in 1966, and up to 1990 and an area of 0.12 million hectares had been brought under plantations which have substantially increased the total area of mangrove during the early 1990s. Primarily, the plantation was restricted to the commercially important species. At present, trials with all the commercially important plant species are being carried out with the objectives of accelerating the process of siltation and stabilization of soil, creating forest shelterbelts to protect life and property of inland from tidal bores, creating an urgently needed resource to add to the national wealth, creating job opportunities for the rural communities, and creating an environment for wildlife, fishes and other estuarine and marine fauna. The Forestry Master Plan (1993) suggested two scenarios. The first one proposed an annual planting target of about 18 000 ha during 1993–2002 and 21 000 ha during 2003–2012. However, use of quality planting material, site preparation and post-establishment maintenance has not been given adequate attention. Due to budgetary and legal constraints adequate protection of plantations from fire, grazing, illegal removal and encroachment has not been provided. The second scenario emphasizes on the development of wildlife sanctuaries although these three sanctuaries are not sufficient to provide long-term protection to the wildlife of the forest. Current management objectives as per the Master Plan aim at enhancing environmental preservation and conservation ;introducing rational forest land use; increasing public participation and benefits from resource management; expanding the resource base; improving management practices; and undertaking efficient resource allocation; and forest management plans. In recognition of the importance to manage the forest resources in the Sundarbans Reserve Forest (SRF) on a sustainable basis, the Forest Department imposed a logging moratorium in 1989 on all timber species except Gewa. The primary goal of the Aquatic Resource Program is to put into place an effective management system for the aquatic biodiversity (fishes, crustaceans and mollusks) of the Sundarban, which will both protect vulnerable species and allow sustainable harvesting of fish resources over the long term. The problems associated with management of the mangrove resources are many and varied. These problems are closely related to the rapid destruction of the mangroves, conversion of mangroves to aquaculture and other forms of land uses and other related impacts. Mangroves are very complex ecosystems formed by interactions between land, water, flora and fauna. But the country’s management policies are such that, in most cases, management policies are formulated separately for each individual unit by the authorities concerned. In most instances, there is no coordination between different sectors, and their policies are conflicting. The need for a quite different management strategy for mangrove forests rather than managing separately each unit has not yet been realized. As a result, effective exploitation, management and conservation of mangrove resources are far away. Poor management policies, weak organizational and legal efforts, the population pressure, above all, the water transfer strategy at the upstream taken by India have subjected the mangrove forests to massive destruction. Destruction of mangrove resources in Bangladesh is so high that irreversible long-term changes have taken place in the ecosystem affecting the balance and sustenance of the system. Great Forest in Great Danger: Threats to Biodiversity Mangrove forests are one of the most productive and bio-diverse wetlands on earth. Yet, these unique coastal tropical forests are among the most threatened habitats in the world as experts' fear they may disappear more quickly than inland tropical rainforests because of lack of public notice. The threats to the Sundarban mangrove eco-system are arising partly due to biotic pressure from the surrounding environment and, partly due to human induced or natural changes in the upper catchments. These can be outlined as below: �� Anthropogenic impacts like reclamation, human encroachment and influence �� Geomorphic stress caused by the neo-tectonic tilting of the Bengal basin �� Recurrent coastal flooding due to climate change (global warming), changes in sea level (raise in sea level) �� Huge silt deposition, biodiversity loss and regeneration problems of obligate mangrove plants �� High salinity, low water table and acidity problem, loss of soil fertility, coastal erosion and a steep fall in fishery resources �� Reduction in the periodicity and quantity of freshwater reaching the mangrove environment due to diversion of freshwater in the upstream areas (especially due Farakka Barrage constructed by India) and change in course of main rivers �� Conversion of mangrove tracts for aquaculture and agriculture �� Extension of other non-forestry land use into mangrove forest �� Increasing demand for timber and fuel wood for consumption �� poaching of tiger, spotted deer, wild boar, marine turtles, horse shoe crab etc �� Uncontrolled collection of prawn seedlings �� Uncontrolled fishing in the water of Reserve Forests �� Continuous trampling of river/creek banks by fishermen and prawn seed collectors �� Pollution from both the landward and seaward sides through marine paints & hydrocarbons, usage of excessive pesticides & chemicals for agricultures & industries, exploitation of mineral gas and oil etc �� Organizational and infrastructure deficiencies �� Lack of public awareness. A number of species like Javan rhinoceros (Rhinoceros sondaicus), water buffalo (Bubalus bubalis), swamp deer (Cervus duvauceli), gaur (Bos gaurus), hog deer (Axis porcinus) and marsh crocodile (Crocodilus palustris) became extinct during the last 100 years from the Sundarban. The Royal Bengal Tiger is an inseparable part of the legend attached to the Sundarban. The tidal mangrove forest is a rare habitat for this tiger species. But today they have been pushed due to habitat shrinkage. The tiger population estimate in the past 20 years remained in the range of 350 to 400, the largest discrete population of the species in a single tract of natural habitat in the world. But the preservation of the Royal Bengal Tigers is, by far, the most important challenge for those concerned for the protection of Sundarban bio-diversity. Incidental mortality due to diseases, illegal hunting and subtle changes in the Sundarban ecosystem poses a serious risk for the survival of the Royal Bengal Tiger. Apart from that, the interaction with humans in the area, particularly the killing of humans by tiger, complicates the management of the area. IUCN has listed it as an endangered species in its Red Book. The marsh crocodiles, once abundant, are already extirpated. The salt-water crocodile (Crocodylus porosus) still survives in low densities and like the marsh crocodiles its population is being reduced through indiscriminate hunting and trapping for skins, quite apart from the immediate conflict with men. Despite an apparent reduction in illegal trade in its skin, the population shows little sign of recovery. Some 30 species of snakes have been recorded and there appears to have been a general decline in densities or at least in their sighting particularly in the past two decades. The Rock Python (Python molurus) is one of the rare snake species, which is said to have declined over recent years. IUCN has listed it as a "vulnerable species." It is estimated that 1,570 km2 mangroves were reclaimed in the three decades since 1947. The results of four independent inventories undertaken over the past seventy years indicate that the overall volume of wood per hectare has decreased. Moreover, closer analysis of three inventories undertaken in 1959, 1983 and 1996 indicate a marked reduction in total standing volume for the two principal species of economic importance, Sundari and Gewa. The mean volume per hectare of the Sundari tree was 34.5 in 1959. The volume was reduced to 19.9 in 1983 and 17.8 in 1996. In case of Gewa, the mean volume per hectare was 8.7 in 1959, which was reduced to 4.6 in 1983, and 2.1 in 1996. The dramatic decrease is blamed on their over exploitation, legally and illegally, because of their commercial value and subtle changes in the ecosystem. A number of issues related to the Sundari, Gewa and Goran trees have emerged for immediate concerns of the foresters. Human activities, such as illegal logging, tourism industries, unplanned development projects, forest clearing and subsequent conversion to other land uses directly contribute to mangrove forest loss. Thus major threats to biodiversity have come mainly from the growing human population, and consequently, overexploitation of both timber and fauna, and conversion of the cleared land to agriculture and aquaculture. Today, the area around the Sundarban is densely populated and they depend on Sundarban for their livelihood. Numerous people are engaged in the commercial exploitation of sundari and other tree species, while the local people depend on the forest for firewood, timber for boats, poles for house-posts and rafters, golpatta (Nipa fruticans) leaf for roofing, grass for matting and fodder, reeds for fencing, and fish for their own consumption. Honey and wax are collected during the summer season (April to June) and thousands of fishermen harvest fish and shrimps for most of the year except in the monsoon season. In recent years, collection of shrimp juveniles has increased manifold, particularly for aquaculture in reclaimed areas. The expanding shrimp farming in the greater Khulna region has caused wide concerns for the rich bio-diversity of the Sundarban. Experts say indiscriminate shrimp and salt cultivation already destroyed the valuable mangrove forest in Chokoria Sundarban and fear that its ecosystem would be in jeopardy for the same reason in the near future. Commercial hunting was a problem mainly before the 1970s and this resulted particularly in a serious depletion of the crocodile populations and to a lesser extent to the deer population. Although wildlife protection has improved significantly in the last decades, illegal hunting is still occurring on an incidental basis and fishery is having an adverse impact on the remaining turtle and crocodile populations as these animals are frequently caught up in fishing nets. The Sundarban mangroves lie on a delta that is relatively young geologically and has been undergoing drastic changes. These changes are caused by geotectonic activity that is causing the tilting of the delta towards the east, and by the enormous amounts of sediments transported by the rivers originating in the Himalaya. The accretion of sediments in the western part and the tilting to the east causes the river to migrate eastwards. Most of the distributaries of the River Ganga on the Indian side have already silted up and do not carry. Thus, increased levels of salinity, particularly during the dry season (low flow period) affect biodiversity, with the salinity-tolerant species gradually overtaking species dependent upon regular freshwater inputs. Many plant species like Heritiera fomes, Nypa fruticans and Phoenix paludosa were very abundant in the Sundarban 50 years ago, but recently they have declined relatively as the salinity has increased. As a long-term consequence Heritierais being replaced by Excoecaria. In general, the forest structure is becoming simpler and the average height of the trees is decreasing. It is estimated that in the Bangladesh part of the Sundarban, 0.4 % of the forest area is replaced by dwarf species every year. This also causes a decline in the habitat for birds, monkeys and other tree-dwelling species. While the deterioration in vegetation is already well documented and receives continuing attention, the impacts of these changes on the fauna, particularly invertebrates, have not been investigated. Reports suggest that the changes in herbaceous vegetation are affecting the population of spotted deer which now has a much lower population in the western areas where salinity is the highest. The changes in freshwater flushing are visibly caused by gradual eastward shift of the flow of the Ganges River. In the Sundarban, the tidal water is the main source of salinity which is counter balanced by the flow of fresh water coming through the rivers from the upland region of Nepal, India and Bangladesh. But in recent time freshwater flow through these rivers has decreased considerably especially due to Farakka Barrage constructed by India in the upstream on the Ganges in 1974. Subsequent siltation in the Gorai is accelerating the process. This has proved to be a threat to the unique biota of the forest, specially the flora. Top dying of Sundri in the Sundarban, the most serious of all the diseases and disorders of tree species, is considered due to reduced flushes of fresh water resulting in increased levels of salinity and reduction in nutrient replenishment. The infectious top-dying disease of Sundari causes another management problem as experts said poor execution of infected trees invalidates the basic rationale for the "sanitation/salvage" method to save the uninfected trees. Long delays between marking and cutting causes more trees in an area affected by top dying eventually exposing them to "axes instead of saws." It is believed that the changes affecting the salinity, flood intensity and periodicity, erosion, siltation and sedimentations may all be factors for perplexing and worrisome loss to the world's largest mangrove system. Moreover, India wants to transfer the ‘surplus’ water from its north and north-eastern parts, the Ganges and Brahmaputra basins, to the water ‘deficit’ basins, the southern regions, through river-linking mega project, which would aggravates the situation in the Sundarban further. Indian river-linking plan would induce significant changes in the hydrological ecosystem of the Sundarban and drastically worsen the salinity problem which may severely affect the vegetation resources of the Sundarban. Further threats to biodiversity because of pollution have arisen on both the landward and seaward sides of the mangrove. The agrochemicals (fertilizers and pesticides) used extensively in the catchments of the Ganga and Brahmaputra rivers and their numerous tributaries, as well in the fields close to the mangroves, pollute both the waterways and the landmass, and affect the aquatic vegetation and fauna directly. Moreover, toxic products and urban wastes enter the system due to upstream pollution in the huge Ganges catchments. Pollution may not be a direct source of mortality, but it may also reduce the health of the forests, increasing the mortality rate of the flora and fauna on the long term. Growing industrialization of the areas contribute significantly to the pollution load and hence, to the degradation of the Sundarban mangroves. From the seaward side, major pollution occurs through oil spills that cause great damage, especially to the aquatic fauna and seabirds. Recently, the off-shore exploration for oil and gas by both Bangladesh and India has raised strong protests concerning fears about its likely impacts on the Sundarban’s biota. It is now clear that slowly but far-reaching changes are taking place pervasively in the Sundarban. These arise from direct and indirect impacts of human influence in the area causing widespread quantitative and qualitative degradation of the resource base throughout the Sundarbans eco-system. According to forest inventory, it is clear that the level of illicit takeoff, some purely illegal and some quasi-sanctioned, may be quite larger than what could be scientifically justified for sustainable management of the Sundarban ecosystem. Consequence of Mangrove Deforestation and Future of the Sundarban Deforestation of Sundarban has a great negative impact on its ecosystem. In Sundarban, like many areas of the world, mangrove deforestation is contributing to fisheries declines, degradation of clean water supplies, salinization of coastal soils, erosion, and land subsidence, as well as the release of carbon dioxide into the atmosphere. With regard to the Sundarban, experts have sounded caution that destruction of the forest will not only affect the ecology but cause far reaching impacts on national economy and causing immense damage to the marine resources of the Bay of Bengal, still economically unexplored and unexploited by Bangladesh. The loss of the Sundarban would also expose the entire southwestern region of the country to frequent cyclones and tidal surges. Every year a good number of tidal surges hit Bangladesh's south and southwestern coastline and the Sundarban bears the brunt acting as a vital barrier against all such calamitous lashings of the nature to protect the country's southwestern coastlines including the regional towns and cities like Mongla and Khulna. Large areas of the Sundarban mangroves have already been converted into paddy fields over the past two centuries, and more recently into shrimp farms. The Sundarban has been extensively exploited over centuries for timber, fish and prawns, fodder, or converted for paddy and aquaculture. While conservation efforts have focused on wildlife, particularly tiger, through creation of several sanctuaries and a biosphere reserve, reduced freshwater inflows are a serious threat as salinity is rising. Heritiera fomes(locally called Sundari), Nypa fruticans and Phoenix paludosa are declining rapidly. Other threats to biodiversity come from the growing human population, pollution, and a rise in sea level. The regulation of river flows by a series of dams, barrages and embankments for diverting water upstream for various human needs and for flood control has caused large reduction in freshwater inflow and seriously affected the biodiversity because of an increase in salinity and changes in sedimentation. During the past three decades, although some attempts have been taken to protect this unique ecosystem, its biodiversity continues to be threatened by a growing human population that not only places pressure on its biological resources, but also impacts on the freshwater inflows from upstream areas especially for Indian activities. Oil exploration in coastal areas is also emerging as a new threat. Further threats arise from global climate change, especially sea level rise. The future of the Sundarban will depend upon the management of freshwater resources as much as on the conservation of its biological resources. Two major factors will determine the future of the Sundarban mangroves and their biological diversity. First, the demand on freshwater resources is bound to grow as the human population in both countries continues to increase, resulting in the restriction of freshwater flows to the monsoon season when extensive floods occur in the eastern parts of India and in Bangladesh. The resultant increase in salinization and accretion of sediments may alter vegetation composition. Impacts on animal communities may also occur due to both, the direct effects of salinity and indirectly through food chain modifications caused by the alterations in the nature and amount of detritus available in the mangrove ecosystem. Therefore, it is the human response to the spatial and temporal variability in precipitation, and hence the freshwater availability, which will determine the water availability for sustaining the functions and values of the mangroves. The proposed plan of India for the inter-basin transfer of water through a river-linking program has already raised concern for the fate of the Sundarban and its rich biodiversity, as well as for the major parts of Bangladesh. Secondly, global climate change is expected to increase the average temperature and spatial-temporal variability in precipitation, as well as cause a rise in sea level (Ellison, 1994). The increase in temperature and variability in rainfall will put further pressure on freshwater resources and hence, alter the freshwater inflows to the mangroves. If precipitation declines in the Ganga-Brahmaputra basins it may lead to a further reduction in the availability of freshwater in the deltaic region. Some models of climate change also present an increased frequency of tropical cyclones and storm surges, which may cause further changes in freshwater-seawater interactions and hence affect the mangroves. Substantial areas of the Sundarban along the coast are expected to be inundated by seawater in this case, and the increased landward salinity intrusion would affect the biotic composition. Ultimately, the future of the Sundarban mangroves hinges upon the efficiency of managing the limited freshwater resources for meeting both human and environmental needs, coupled with effective adaptive responses to the added threats from climate change. However, the future sustainability of the Sundarban will be contingent upon political will of the Governments of India and Bangladesh and continued support from the International agencies in respect to protect this unique wildlife feature of the world.Far-reaching changes are taking place slowly but steadily in the Sundarban region for years together due to direct and indirect impact of human interventions which are affecting its delicate ecosystem. Although the role of such changes is not yet clearly visible, but is evident that it will influence wildlife populations and vegetation in the long term. Today, these negative and menacing impacts are threatening the existence of the mangrove ecosystem. Massive changes in both the adjacent agricultural lands and upstream areas with construction of polders, embankments or barrages are feared to have been generating fundamental changes in the hydrological regime of the Sundarban. Due to natural processes the role of the Sundarban to discharge the water of the Ganges and Brahmaputra catchments is decreasing as main waterways are shifting eastwards. As a result, the salinity of the Sundarban is increasing -- particularly in the western region. The total annual discharge is decreasing due to intensifying land use in the upstream. Further, the decision taken by India for the construction of a mega river-linking project to withdraw the water form the main stream will cause serious problem in supplying the freshwater to Sundarban which will destroy the mangrove ecosystem. Mangrove forests once covered three-fourths of the coastlines of tropical and sub-tropical countries. Today, less than 50 percent of that is surviving. And then again, of this remaining mangrove forests, over 50 percent has been degraded and not in good form. Greater and comprehensive protection measures should be taken in national and international level for maintaining the high quality mangrove forests with a large biodiversity-rich ecosystem like the beautiful forest ‘Sundarban’, a World’s Heritage Site.Urgent steps are necessary to stop and reverse the current trend of deforestation and loss of biodiversity in the Sundarbans Reserve Forest (SRF), which is under pressure from a growing number of users. SRF has to be managed by an institution capable of managing a multidimensional resource. In addition to increased financial resources, a significant improvement in the institutional capacity of the Forest Department (FD) and an improved management approach based on appropriate research, community participation, and scientific planning is necessary.

Saturday, August 1, 2015

Robot can leap from water’s surface August 1, 2015 11:56 am

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