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CHAPTER 3. INTERPRETIVE DESCRIPTION OF THE REGION'S WETLANDS
3.1.1 The Northeast Region
The Northeast Region covers an area of approximately 24,500 sq km, bounded by the international border with India to the north and east, the Old Brahmaputra to the west, and the Nasir Nagar (to Madhabpur) and Meghna rivers to the south (Figure 1). The greater part of this region is taken up by the haor basin which comprises the floodplains of the Meghna tributaries, and is characterized by the presence of numerous large, deeply flooded depressions, known as haors, between the rivers. This vast alluvial plain possesses some 6,000 permanent shallow water bodies known as beels (usually in the lowest parts of the haors or in abandoned river channels), surrounded by large areas of seasonally flooded plains. The basin is bounded to the north by the hill ranges of Meghalaya, to the south by the hills of Tripura and Mizoram, and to the east by highlands of Manipur. The numerous rivers rising in these hills provide an abundant supply of water to the plains and cause extensive flooding during the monsoon season, with much of the region being flooded to a depth of up to six metres. The drainage is southwest via the Surma, Kushiyara, Baulai, and Kalni rivers into the Meghna River and Bay of Bengal. Almost all land above the maximum flood level is under permanent cultivation and human settlement. There are extensive plantations and groves of trees around most villages and homesteads, and in many areas this creates an aspect of discontinuous forest.
The climate is subtropical monsoonal with an average annual rainfall of approximately 4,000 mm. Over 80% of the rain falls during the monsoon season from June to October. Temperatures normally vary between 26 and 31 C in the pre-monsoon period (Mar to May), 28 to 31 C in the rainy season, and 26 to 27 C in winter. Extreme temperatures at Sylhet in the ten-year period 1975-1984 were 6.4 and 39.3 C.
A large number of water resources development projects have been constructed (Regional Water Resources Development Status, NERP, 1992) and still more are proposed for the region (Northeast Regional Water Management Plan, NERP 1993).
3.1.2 The wetlands of the Northeast Region
The haors, from which the region's central basin takes its name, are back swamps or bowl-shaped depressions between the natural levees of rivers, or in some cases, much larger areas incorporating a succession of these depressions. The haors flood to a depth of as much as six metres during the rainy season, and in many cases two or more neighbouring haors link up to form much larger water bodies. During the dry season, most of the water drains out, leaving one or more shallow lakes (beels). Many of these become overgrown with aquatic vegetation, and some dry out completely by the end of the dry season. The term beel is also used for oxbow lakes and other permanent water bodies in abandoned river channels; these are especially numerous along the lower courses of the Baulai and Kalni Rivers. As the monsoon flood waters recede during the dry season, rich alluvial soils are exposed around the margins of the beels, and these are extensively cultivated for rice.
The haor basin contains about 47 major haors and some 6,300 beels of which about 3,500 are permanent and 2,800 are seasonal. These wetlands vary in size from as little as a few hectares to many thousands of hectares. The principal systems are as follows:
Currently, the haors, beels, and ponds support major subsistence and commercial fisheries, the seasonally flooded plains support a major rice-growing industry, and the abundant aquatic vegetation provides rich grazing for domestic livestock and a source of fuel, food and fertilizers for the local people.
The region contains all of the nation's remaining large semi-natural freshwater wetlands, a landscape once characteristic of much of the country. The wetlands are home to a very wide variety of resident and migratory waterfowl, including an estimated 100,000 to 150,000 ducks, and provide a refuge for many other species of wildlife which are becoming increasingly rare elsewhere in Bangladesh.
There has been mass extinction of the native flora and fauna of the haor basin of Northeastern Bangladesh. In its original form, the basin would have consisted of a rich mosaic of permanent and seasonal lakes and ponds with abundant aquatic vegetation, surrounded by vast areas of swampy ground with tall reeds and seasonally flooded grasslands. Swamp forest, dominated by Barringtonia, Pongamia, and other flood-tolerant tree species, would have covered the river levees, and provided a secure refuge for terrestrial wildlife during the monsoon floods. On higher ground, this would have given way to scrub jungle and dense stands of bamboo.
Wildlife would have been abundant. Marsh Crocodiles and Otters would have been common in every lake and swamp. One-horned Rhinoceroses, Wild Buffalo, and Swamp Deer would have grazed in the marshes, and Asian Elephants, Gaur, Sambar Deer, Hog Deer, and Wild Boar would have roamed the forests and tall grasslands. Tigers and Leopards would have been common, along with many smaller predators such as Wolves, Jackals, and several species of wild cat. And everywhere, there would have been birds -- teeming flocks of migrant ducks and shorebirds from Siberia mingling in winter with the resident flocks of cormorants, pelicans, herons, egrets, storks, ibises, whistling-ducks, comb ducks, pygmy geese and many more species. During the breeding season, there would have been huge mixed colonies of cormorants, herons and storks in the patches of forest, while the marshes would have rung with the bugling calls of Sarus Cranes.
Today, although most of the permanent water bodies have survived, all other ecosystems have almost completely disappeared. Vast areas of the seasonally flooded plains have been converted to rice monoculture, while areas less suitable for rice are now heavily grazed by domestic livestock or cultivated for wheat and other crops. The swamp forests have been reduced to a few small patches, often no more than ten or twenty widely scattered and now very old trees, while virtually all land above the level of the monsoon floods has been utilized for permanent settlement, homestead forests, and public infrastructure. The swamp forests, scrub jungle, bamboo thickets and dense stands of reeds have disappeared almost without trace.
Although we have no good contemporary accounts of the haor basin in its natural condition, we can gain an impression of how it would once have appeared by visiting comparable areas in neighbouring countries where these ecosystems still survive in more or less their natural form. Kaziranga National Park and Manas Wildlife Sanctuary in Assam and Royal Chitwan National Park in Nepal still retain outstanding examples of floodplain wetland ecosystems and their associated forest communities, and provide a vivid contrast to the totally man-modified environments which now exist over most of the plains of the Ganges and Brahmaputra systems. Indeed, these three large and well-protected sanctuaries have become critical to the continued survival of a whole group of wildlife species which have now become extinct over most of their former ranges. These include the One-horned Rhinoceros Rhinoceros unicornis, Swamp Deer Cervus duvauceli, Hispid Hare Caprolagus hispidus, Swamp Partridge Francolinus gularis, Bengal Florican Eupodotis bengalensis and Marsh Babbler Pellorneum palustre -- all now listed as threatened in the Red Data Book (IUCN, 1990a).
The international significance of the wetlands of the haor basin for their waterfowl populations was first drawn to the attention of the international conservation community at an International Regional Meeting on Conservation of Wildfowl Resources held in St. Petersburgh (at that time Leningrad) in Sep 1968. At that meeting, Savage (1970) and Savage and Abdulali (1970) presented papers on the status of the main wildfowl resorts and wildfowl species in East Pakistan. They identified four wetland systems within the haor basin as being of special importance for waterfowl: Tangua Haor, Hakaluki Haor, Kawadighi Haor, and Hail Haor.
Further information on the important wetlands of the haor basin was presented by Fazlul Karim on behalf of the Forest Department at an International Conference on Conservation of Wetlands and Waterfowl held in Heiligenhafen, Germany, in Dec 1974 (Forest Department, 1976). This report placed special emphasis on the importance of Hakaluki and Hail Haors for their rich and diverse waterfowl populations. More recently, Scott and Poole (1989), in their Status Overview of Asian Wetlands, stressed the importance of the wetlands of the haor basin, and urged that ongoing studies in the region be expanded with a view to the development of a regional wetland management plan.
Directory of Asian Wetlands
Two years prior to the NERP study, the wetlands of the haor basin were described in the Directory of Asian Wetlands (Scott, 1989). The Directory's information on the wetlands of Bangladesh was provided by Abdul Wahab Akonda of the Forest Department, and by S.M.A. Rashid and Raguib Uddin Ahmed of the Wildlife Society of Bangladesh.
The Directory identifies the wetlands of the haor basin of Sylhet and Mymensingh as a wetland ecosystem of outstanding international importance on the basis of criteria established in relation to the Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat.
The Directory treats the haor basin as a single wetland system. However, within this system, six of the larger haors and four individual beels are singled out as being of special importance for their wildlife, and are described in greater detail. Four of the haors (Tangua, Hakaluki, Kawadighi, and Hail) had long been known to be of outstanding importance for their waterfowl populations, while recent field surveys by Akonda, Rashid, and Ahmed had indicated that the other six sites (Dekhar Haor, Dubriar Haor, Meda Beel, Aila Beel, Kuri Beel, and Erali Beel) could at times support large numbers of waterbirds. However, much of the region remained poorly known, and it was acknowledged by these authors that other sites, equally important for wildlife, might remain to be discovered.
The Directory identified ten key sites within the haor basin. These sites were apparently selected for one of two reasons: either they were sites which had long been known to be of special importance for wildlife (Tangua Haor, Hakaluki Haor, Kawadighi Haor, and Hail Haor), or they were sites which the contributors to the Directory had surveyed and found to be particularly interesting (Meda Beel, Aila Beel, Dekhar Beel, Kuri Beel, Erali Beel and Dubriar Haor). It was recognized at the time that this list was not comprehensive, and that other equally interesting sites for nature conservation might remain to be discovered.
Most of the published literature on the region, especially the earlier material, consists mainly of anecdotal information and descriptions of specimens collected in the area. These materials are discussed below under the appropriate resource subsystem (flora, water fowl, wild life). A more recent and detailed account of the wetland ecosystems of the haor basin is given by Syed Iqbal Ali (1990).
3.2 WETLAND APPRAISAL
The wetlands of the Northeast can be classified as follows:
A Wetlands of international importance. These are large sites comprised of either a single large beel (Hail Haor) or a group of beels that are of outstanding importance for wildlife and retain some natural qualities of considerable ecological significance in a regional context. These sites clearly qualify as wetlands of international importance on the basis of the Ramsar criteria (Tables 2.1a and 2.1b) for identifying wetlands of international importance. These give prominence to overall importance for wildlife, especially waterfowl, and characteristics such as representativeness, uniqueness, high ecological diversity, and presence of threatened species.Table 3.1 shows the ranking of the major haor systems and the individual sites within them based on the initial wetland appraisal only. Note that the ranking is never absolute: a site can increase in rank if additional information documenting its value becomes available, and can decrease in rank if its ecological character were significantly compromised. Indeed, this is what happened: the initial list of six key wetland sites was expanded to nine, to reflect additional information gathered during the year of field studies (see next paragraph).
3.2.2 Wetlands of international importance (A sites)
Nine systems were identified as of outstanding national and international importance for their nature conservation values. They are:
1. Tangua Haor
Tangua Haor is of outstanding importance for its large and diverse waterfowl populations. It is perhaps the most "natural" large wetland remaining in the Northeast Region, and possesses extensive stands of emergent marsh vegetation. There is little permanent human settlement in the immediate vicinity, and there remain significant areas of higher ground between the beels which are not under cultivation and which still support some natural herbaceous vegetation.
This haor forms the core area of the northern haor system, which includes several other haors also of importance for waterfowl (such as Gurmar Haor, Kanamaiya Haor and Matian Haor). The Tangua Haor site itself consists of a group of large beels to the west of the Patnai Gang, close to the Indian border; its principal beels are Pana, Rauar, Tangua, Ainna, Arabiakona, and Samsar. Tangua Haor as a whole is unprotected from flash-flooding, although Arabiakona Beel and one or two small beels are surrounded by submersible embankments.
The presence of a complex of large and relatively undisturbed beels still in a near-natural condition at Tangua Haor is undoubtedly a key reason for the major concentrations of waterfowl found in the northern system as a whole. The northern haors mentioned above together held 71% (76,500) of all waterfowl observed in Feb/Mar 92 and 44% (13,480) of those observed in Apr/May 92. The corresponding figures for Tangua Haor itself were 24% and 11%, respectively.
Largely confined to the northern system of haors are many species of waterfowl, especially the cormorants, Oriental Darter, several species of ducks and Eurasian Coot, undoubtedly because the system provides the largest contiguous area of permanent water in the region and remains relatively thinly populated. The outstanding importance of this system for some waterfowl species is demonstrated by the results of the Feb/Mar 92 survey (Table 3.2). The northern system is also very important for herons and egrets. It held 49% of all herons and egrets recorded during the Feb/Mar 92 survey and 68% of those during the Apr/May 92 survey.
Tangua Haor was identified as a key site in the Directory and is described there in some detail. Three of the main beels, Pana, Rauar and Tangua, were included in the NERP monthly ornithology/ecology monitoring programme.
2. Pashua Beel, Gurmar Haor
The main value of Pashua Beel lies not so much in the beel itself, as in the fact that the surrounding area supports much the finest stands of natural floodplain vegetation located during the present surveys. These include a dense stand of Pongamia pinnata (koroch) forest, large areas of tall grasses and patches of dense shrubbery. Although the main beel is intensively fished and there are a few small rice fields near the river embankment, there has obviously been little other exploitation in the area in recent years. Some people were observed harvesting grasses on the shores of the beel, presumably for fodder, but otherwise the area was undisturbed.
The Pashua Beel site consists of a single large beel with two smaller beels nearby in the extreme southeast portion of Gurmar Haor, adjacent to the Patnai Gang. The beels are surrounded by higher ground with dense grasses, scrub and Pongamia forest, the entire area covering about 400 ha. Gurmar Haor has recently been surrounded by a submersible embankment to protect against flash-flooding (Gurmar Haor Project, completed in 1991).
The importance of Pashua Beel in a regional context is quite outstanding. It contains what would appear to be the best remaining examples of the Pongamia forest and tall grassland ecosystems in the Northeast Region. It provides a secure roosting site for huge numbers of cormorants, herons and egrets (at least 4,600 in late Apr 92), and supports a number of species which are scarce or local elsewhere in the region (e.g. Purple Heron, Black-headed Ibis, Spot-billed Duck and Purple Swamphen). A large flock of Asian Openbills frequented the area from at least early Mar 92 until late Apr 92, and numbered about 400 at the end of Mar 92. Very few of this scarce species were observed elsewhere in the Northeast Region during the present surveys. Concentrations of 19 Pallas's Sea-Eagles in early Mar 92 and 28 in late Mar 92 are of great significance, as this is a globally threatened species. Finally, the area supports a much higher diversity of waterfowl and other wetland birds than any other site investigated. Fifty species of waterfowl were recorded at the beel during the two main surveys - 56% of all the species recorded during the surveys. Many passerines were observed in the surrounding forest and shrubbery.
Pashua Beel was leased to the Pearl and Fishery Resources Development Program on a nine-year lease in 1983. The head of this program is reported to have been a Minister under the Ershad regime. Armed guards were stationed at the beel to prevent illegal fishing, but it is apparent that these guards, and perhaps also a respect for the Minister, were effective in preventing other forms of exploitation as well. The lease came up for renewal in 1992 and was given out to a Member of Parliament on a three-year basis. So far this new lessee is maintaining the same level of protection as under the previous lease.
Pashua Beel was not mentioned in the Directory, as its importance had not been recognized at that time. The site was included in the Monthly Monitoring Programme.
3. Hakaluki Haor
Hakaluki Haor has long been known to be a major wintering area for migratory waterfowl, especially ducks, and is a popular duck-hunting area for sportsmen from Dhaka. The haor remains very important for wintering ducks, despite high levels of disturbance from hunters and fishermen, and is also a very important wintering area for migratory shorebirds. However, it seems to be much less important for cormorants, herons, and egrets, and appears to have only limited value for breeding birds. During the Feb/Mar 92 survey, Hakaluki Haor held 34% of all the waterfowl recorded, including 44% of the ducks and 31% of the shorebirds, but only 3% of the cormorants and 2% of the herons and egrets. At this time, the haor was particularly important for Great Crested Grebes (41% of the total), Lesser Whistling-Duck (67%), Northern Shoveler (73%), Little Ringed Plover (49%), Kentish Plover (86%), Asiatic Golden Plover (53%), Little Stint (74%) and Marsh Sandpiper (56%). During the Apr/May 92 survey, the relative importance of the haor had fallen considerably, and it now held only 8% of all waterfowl recorded (with 14% of the ducks and 12% of the shorebirds).
The Hakaluki Haor site consists of a large group of beels surrounded by heavily grazed grassland and rice fields.
Hakaluki Haor was identified as a key site in the Directory, and is described in some detail. Three of the main beels, Haor Khal, Chatla Beel, and Pingla Beel, were included in the Monthly Monitoring Programme.
4. Hail Haor
The nature conservation values of Hail Haor relate primarily to its unique status in the region as the largest, shallow, permanent lake. The lake supports a very rich and diverse aquatic plant community, which in turn supports a wide variety of resident bird species, several of which are scarce or local elsewhere in the region (Yellow Bittern, Purple Heron, Watercock, Purple Swamphen and Black-breasted Weaver). The lake would undoubtedly be of great importance for wintering waterfowl were not it for the high levels of disturbance from fishing activities.
The Hail Haor site is a very large, rather isolated, shallow permanent lake with extensive floating and emergent vegetation, surrounded on three sides by low hills. It thus differs considerably in character from most other haors in the haor basin. The haor is included within an ongoing flood control and drainage project initiated in 1985 (Hail Haor Project). The project seems to have had little effect on the hydrologic regime within the basin, however.
Hail Haor was identified as a key site in the Directory, and is described in some detail. Parts of the haor were included in the Monthly Monitoring Programme.
5. Kaliajuri Area
Kaliajuri Area is a relatively undisturbed area representative of the deeply flood zone. It has also been identified as a mother fishery. The area has some swamp forest patches, and in the dry season extensive areas of winter grasses, such as Hematheria protensa chailla which is rot resistant and widely gathered and used in the construction of homestead erosion protection works.
6. Companiganj Area
Companiganj Area contains the best reed swamp remaining in the region and also has some floodplain grassland, which may be habitat for one or more threatened passerine bird species. It has also been identified as a mother fishery. Otters and large concentrations of turtles have been observed.
7. Bara Haor
Bara Haor contains the best floodplain grassland habitat remaining in the region, and some reed swamp and swamp forest areas. Breeding cormorants and breeding herons have been observed. As at Companiganj Area, the floodplain grassland may be habitat for one or more threatened passerine bird species.
8. Kawadighi Haor
Kawadighi Haor remains very important for a wide variety of waterfowl, despite the changes which must have occurred to these wetlands since the construction of the Manu River Project in 1976-83. The haor held 8.5% of the waterfowl recorded during the Feb/Mar 92 survey, and 5.3% of those during the Apr/May 92 survey. The shallow beels with large areas of rotting aquatic vegetation and exposed mud were particularly attractive to shorebirds and several species of herons and egrets. The haor held 16% of all shorebirds recorded during the first survey, and 25% of those recorded during the second. The corresponding figures for herons and egrets were 23% and 17%, respectively. The beels may also be of some importance for breeding birds. In early May, Black-winged Stilts and Whiskered Terns were showing courtship and nest-building behaviour at Petangi Beel. Neither of these species has as yet been found breeding in Bangladesh.
9. Balai Haor
Observations during the present surveys suggest that the area is of special interest for its diversity of fauna and flora, the presence of at least two threatened species (Lesser Adjutant and Pallas's Fish-Eagle), and the presence of large concentrations of ducks during periods of deep flooding. Few ducks were observed at the haor in early Mar 92 and late Apr 92, when water levels were very low, but over 32,000 were present in late Mar 92 when water levels were high. The haor may also be of considerable importance as a staging area for passage migrants, because of its strategic position as the first or last major wetland that migrants encounter on their way to and from the lowlands of the Northeast Region. Much more work needs to be carried out before the importance of the site for nature conservation can be fully determined.
The Balai Haor site is an isolated haor between the Surma and Kushiyara rivers in the extreme east of the project area. It includes three principal beels (Dubail, Jugni, and Khakra Kuri) surrounded by heavily grazed pasture land and rice fields. Most of the many low embankments and margins of the water courses have been invaded by dense stands of the introduced exotic plant Ipomoea acuatica (kalmi) and this is now spreading out into the cultivable areas.
Balai Haor was not mentioned in the Directory. The site was included in the Monthly Monitoring Programme.
Kawadighi Haor comprises two large, shallow beels, Petangi and Majherbanda, and a third, smaller beel, Ulauli, adjacent to the latter. The Manu River Project, within which the haor lies, consists of a full flood control embankment, water control structures, and a pump house for pumped drainage. The project has caused some reduction in wet season water levels, but not as much as anticipated due to public cuts and overland flow from the adjacent Bhatera Hills. It is not clear how nor to what extent the project has actually affected waterfowl, positively or negatively. It seems clear however that if full flood protection were achieved as intended, further changes would occur.
Kawadighi Haor was identified as a key site in the Directory, and is described there in some detail. The haor was included in the Monthly Monitoring Programme. Also, Manu River Project was selected as a NERP project monitoring site.
3.2.3 Wetlands of national importance (B sites)
Hail Haor Fish Ponds
A group of privately owned and well-protected fish ponds south of Hail Haor. These are primarily of interest as a secure resting area for ducks which presumably feed at night in Hail Haor. Monthly Monitoring Programme site.
Patachatal Beel and Borachatal Beel, Maijeil Haor
Two large, deep beels with little emergent vegetation, surrounded by rice fields. Of principal interest as a resting area for wintering ducks which presumably feed in the surrounding rice-fields. Over 4,000 ducks were present in early Mar 9. Patachatal Beel was poisoned with rotenone during the first week of Apr 92 and stocked with carp hatchlings on 26 Apr 92, as part of the Second Aquaculture Development Project supported by the Asian Development Bank. A large numbers of turtles, snakes, and frogs were killed along with the gill fishes, possibly due to misapplication of the poison. Monthly Monitoring Programme sites.
Chalnia Beels, Damrir Haor
Two large, deep beels with little emergent vegetation, surrounded by rice fields. Of principal interest as a wintering area for ducks. A flock of 1,200 Tufted Ducks in late February was the largest concentration of this species recorded during the surveys. A pair of Pallas's Fish-Eagles nests nearby. Monthly Monitoring Programme site.
A large, deep beel with little emergent vegetation, set amongst low hills and relatively isolated. The beel appears to be of very little value for waterfowl, but may be of considerable limnological and/or ecological interest because of its unique character and isolation. This wetland was described as a key site in the Directory. Monthly Monitoring Programme site.
A number of large and small beels, mostly shallow with a considerable amount of floating and emergent aquatic vegetation, surrounded by rice fields. Kuri Beel differs from the others in being much deeper and being surrounded by steep grassy banks. The haor is of some value for a wide variety of wintering waterfowl, and also supports a small number of resident species. Almost 1,600 birds of 30 species were present in late February, including the only Bar-headed Geese recorded during the surveys. Dekhar Haor and Kuri Beel were described separately as key sites in the Directory . Monthly Monitoring Programme site.
Aila Beel and adjacent beels, Panger Haor
A group of four large beels and several smaller beels with some emergent aquatic vegetation, surrounded by rice fields. The system lies within a submersible embankment (Panger Haor Project). Apparently an important wintering area for ducks, gulls and terns. No survey was possible in late Feb 92 or early Mar 92, but a survey on 22 Mar 92 revealed 9,600 birds including 3,600 ducks, almost 400 Brown-headed Gulls, and 5,000 Whiskered Terns. On 21 Apr 92, the beels held over 8,000 ducks, the most recorded at any site during the Apr/May 92 survey. Aila Beel was described as a key site in the Directory.
Kanamaiya Haor including Pakertala Beel
Two large unprotected beels on the Patnai Gang, with some emergent aquatic vegetation. The beels are separated from adjacent Gurmar and Mohalia haors by submersible embankments. Of considerable importance for wintering ducks and shorebirds, holding almost 7,000 waterfowl in early Mar 92 when water levels were low, but of little if any importance for breeding birds. Much of the importance of this and the following site is likely to be related to the presence of the very important Tangua Haor a few kilometres to the north and Pashua Beel a few kilometres to the south.
Bara Beel, Banuar Beel, and Palair Beel, Matian Haor
Three large, shallow beels, with extensive floating and emergent vegetation, surrounded by rice fields. The beels lie within a submersible embankment (Matian Haor Project), and are adjacent to the Patnai Gang. Tangua Haor lies on the opposite side of the river. The beels are important for wintering ducks, and resident cormorants, herons and egrets, Cotton Pygmy Geese and the two species of jacanas. Over 6,300 waterfowl were present in Feb/Mar 92 and 725 in Apr/May 92. The dense aquatic vegetation provides nesting habitat for a variety of species. Monthly Monitoring Programme site.
Meda Beel and Uglar Beel, Ubdakhali Haor
Two medium-sized shallow beels with large areas of floating and emergent aquatic vegetation, surrounded by rice fields. The beels lie within a proposed project area (Ubdakhali). Probably of some importance for wintering ducks, although only 1,130 were recorded in Feb/Mar 92. No survey was carried out in Apr/May 92. Meda Beel was described as a key site in the Directory.
3.2.4 Other sites (C sites)
All the other sites listed in Table 3.1 are considered to be of very little importance for wildlife, other than those common and widespread species which have been able to adapt to man-modified environments and are able to tolerate high levels of disturbance.
The extensive floodplains along the lower Baulai and Kalni rivers, with their innumerable small beels and abandoned river channels, fall into this category. Almost the entire area which is not permanently under water has been converted to rice fields or is now heavily grazed pasture land. Aerial surveys in late February and in early May failed to locate any significant concentrations of waterfowl, and in fact, very few birds were seen other than Indian Pond Herons and several species of egrets. The rice fields may be of considerable importance for some wintering shorebirds, especially the snipe and Wood Sandpiper, but no single area appeared to be of special significance. The scarcity of most waterfowl species can readily be attributed to the absence of any major groupings of large beels (most beels being rather small and widely scattered), the high levels of disturbance from fishing and farming activities, and the almost complete absence of emergent marsh vegetation or other cover.
3.3 FLORA AND FOREST RESOURCES
3.3.1 General ecology of wetland vegetation
Physical environmental factors
Compared with other major natural forms of landscape, wetlands are young and dynamic. Many are physically unstable, changing in a season or even in a single storm. They change as vegetation changes, sediments are laid down, or land sinks. Due to continuous submergence, wetland habitat is characterized by anaerobic conditions which inhibits normal plant growth. A group of plants known as hydrophytes are adapted to withstand these extreme conditions, and these plants colonize wetland habitats.
Within a particular climatic setting (insolation, temperature, precipitation), the geographical and temporal extent of wetlands and the development of particular types of wetland vegetation is governed by the timing and duration of inundation or soil saturation events (hydroperiod), the flow regime, chemical and particulate concentrations (water quality), and soil characteristics. Wetland conditions range from virtually perennial aquatic lowlands to seasonally dry uplands.
Hydroperiod is key to vegetation development and community dynamics. Hydroperiod is affected by topography, flooding and flood type (backwater, overbank), precipitation, and water table fluctuations.
Interannual variability in the timing and nature of the flood regime is important in determining the composition of plant communities and can be responsible for large variations in community distributions. The full extent of its influence is not yet well understood in relation to the germination of plant species.
The nature of the soil also has an important effect on the wetness of an area. Heavy clays drain most slowly and the effects of saturation therefore persist longer in such soils. Soil within the same haor system can vary in texture, drainage class, fertility, and other parameters. This variation can occur in an apparently random pattern, reflecting depositional or other processes that are no longer discernible, or there may be a definite pattern. The transition from the wettest to the driest areas in the floodplains occurs over distances varying from several miles to several meters.
The most flood-tolerant species can live and thrive in swampy conditions. These species can also grow on moist, well-drained sites, but they cannot compete successfully with species that normally inhabit and are specifically adapted to such sites. The least flood-tolerant species cannot tolerate flooding or waterlogging even for a short period. Between these extremes lies a large group of species that can tolerate varying degrees of flooding or waterlogging. Moreover, flood tolerance can vary with life stage. While many plants can withstand flooding for several days during the growing season, only a few plants can survive more than a few days of partial inundation at the seedling stage.
In a heavily populated and extensively cultivated area such as Bangladesh, human activity is also a key factor in determining the extent and composition of wetland plant communities. A general overview of the region's natural history and the impact of human settlement has already been given (Section 3.1); the details of this interaction are presented in the literature review and in the discussion of each vegetation type below.
3.3.2 Previous studies
Botanical exploration in the Northeast Region began with Roxburgh (Hortus Bengalensis, 1814; Flora Indica, 1932) and William Griffith, whose 1835 collecting trip by boat began in Calcutta, passing through Pabna, Jamalpur, Mymensingh, and Habiganj, then along the Surma to Chhatak. During a second trip in 1838 he again travelled along the Surma. During these journeys, he recorded the marsh vegetation and aquatic flora of the jheels and haors. Somewhat later, in 1850, the author of Flora of British India (Hooker, 1872-1897) travelled along the Surma and visited the wetlands of Sylhet.
The first detailed collection of plant specimens from these wetlands was undertaken by Gibson in 1836. He travelled by boat from Calcutta to Dhaka, along the Ganges, and then on to the Surma to Chhatak, returning in 1837 to Calcutta with a full boat load of magnificent specimens. The next major collecting expedition was in 1869, when more than 14,000 specimens were collected by Clarke from Sylhet, Madhupur, and Comilla.
In 1903, the names and drawings of many aquatic plants from the haors of Sylhet appeared in Bengal Plants (Prain, 1903).
Three habitat types in the Sylhet region were identified on the basis of a collation of systematic botanical records (Kanjilal, 1934):
Between the publication of Bengal Plants in 1903 and the creation of independent Bangladesh in 1971, very little systematic botanical fieldwork was undertaken. (The biological science departments of Dhaka University date only to the late 1930s.)
In the 1970s, the Bangladesh Agriculture Research Council took up a 'Botanical Survey of Bangladesh', and in 1975 the Bangladesh National Herbarium was established. Since then, field activities have intensified. A professional journal, Flora of Bangladesh, was established in 1972 and 36 issues were published through 1988.
Microphytes of the haors have also received some attention (for example Islam and Paul, 1978, which presented a hydrobiological study of Hakaluki Haor).
3.3.3 Plant communities (zonation) of the Northeast Region's wetlands
Wetland vegetation can be broken down into a number of communities or types. Each type is an aggregated assemblage of particular plant species, and is characteristic of a particular set of environmental conditions (hydroperiod, flow regime, water quality, soil).
The schematic of haor zonation shown in Figures 3a through 3d illustrates how geomorphologically defined areas are influenced by the fluctuating hydrological regime. Different plant communities occupy different habitats along the gradient of flooding and moisture.
Elements of the sequence of plant communities, or sometimes the entire sequence, may be absent from particular landscapes due to disruption from human activities. In the present study, we have identified eight communities (estimated number of species in parentheses):
The last two communities listed differ from the others in that their composition is strongly affected by human management and disturbance plays; many plants appearing in the other six communities appear in these two as well.
A checklist of the plants (systematic name, Bangla name, and habit) observed in each community is provided in Table D.1. Bangla names of trees and heavily utilized plants are widely known by local residents, and tend not to vary from place to place. Bangla names of smaller and less utilized plants are known now to only a few local people and tend to vary from haor to haor. For these plants, the Bangla names provided were obtained from the literature (Huq, 1986).
The list includes at least 216 species of macrophytic plants from at least 60 families. These include 65 obligate hydrophytes: plants that survive only when submerged in or floating on freshwater, or when on saturated soil. Of these plants, the most abundant belong to the families Gramineae (9 species), Nymphaceae (4), Hydrocharitaceae (5) and Lemnaceae (4). The list also includes about a dozen species of amphibian trees, shrubs, and climbers that prefer seasonally flooded areas. Nine species are exotics.
Kanjilal's upland vegetation no longer exists in community form at the lowland levels we studied. At our swamp forest level, only isolated forest patches remain, and at our crop field and homestead levels natural habitats have been completely displaced by synthetic communities. All Kanjilal's tree genuses survive in the homestead groves, however, except for those that one would expect to find only at higher elevations.
Three of the communities exist only as a few scattered small fragments, and are considered to be threatened: fresh water swamp forest, floodplain grassland, and reed swamp.
1. Submerged plants
The submerged plant community is one of the most prevalent in the haor area. It is comprised of about 20 plant species (Table D.1). Submerged plants remain fully submerged for their entire life cycle, except for the flower which occurs above the water surface. Some are rooted to the bottom and some are freely suspended. All of these plants are monocotyledons, from ten pretty closely related families including Aponogetonaceae, Hydrocharitaceae, and Potamogetonaceae.
These plants are, for obvious reasons, highly susceptible to seasonal water level fluctuations. The community expands in area during the monsoon and contracts with the coming of the dry season. The plants start growing when water levels start rising at the very beginning of the monsoon, persisting throughout the wet season for as long as ample water is present. (In some haors, at the peak of the monsoon when wave amplitude and water depth are greatest, these plants can be very difficult to find.) When the water starts receding, most of these plants flower and fruit very quickly, thereby assuring offspring in the next year; though most of these species have rhizomes and can also reproduce vegetatively. Where the water recedes further, the plants become desiccated and decompose; in permanent water bodies, they can survive for a much longer period.
The composition and prevalence of this community differs from one haor to the next. For example: in Tangua Haor, we found that Hydrilla (kureli, jhangi) and Potamogeton (keorali) were the most abundant species, whereas in Balai Haor Hydrilla, Najas (goisa), Ottelia (panikola, kaorali), Sagittaria (chhotokul) and Aponogeton (ghechu) were the most abundant species. (Hydrilla is common in both haors but much more abundant in Tangua than in Balai.) Still different compositions are found in Hail Haor and Kawadighi Haor.
Community composition also varies between beels within a particular haor system: for example, in Hail Haor, beels such as Chanda situated on the eastern side have dense vegetation while the beels on the western side do not. Kawadighi Haor, Hakaluki Haor, and Murir Haor, also exhibit variation from beel to beel. In other haors, such as Tangua Haor, Balai Haor, and Maijeil Haor, the submerged plant communities of the various beels do not differ significantly.
Community composition also reflects species' water depth and chemical preferences. Most species prefer depths of 0.2 to 2 meters, but some prefer deeper (>2 m) water. Some also have chemical preferences (Utricolaria prefers lower pH, for example, rendering it useful as an indicator species).
2. Free floating plants
Free floating vegetation consists of plants that are most commonly found floating freely on and collecting nutrients from the water; most of them can also survive for a certain period with their roots on or in moist soil. This community is common but not dominant in the haors. It is comprised of about 20 plant species (Table D.1) from the classes Angiosperm and Pteridophytes. The most dominant family in this community is Lemnaceae. Other common families are Salviniaceae, Lentibulariaceae and Pontederiaceae. At the species level Eichhornia (kochuripana), Utricularia (chhotojhangi) and Salvinia (kuripana, indurkan, tetulapana) are the most abundant and can be found in almost all the beels.
This community is also affected by water level fluctuations, though they are in general less dependent on water and more adaptable than the submerged plants. Before the monsoon begins, they are found growing luxuriantly in the stagnant water within individual beels. They persist as the water rises, but as flooding becomes general and the beels fill up, they tend to be advected out from the haors into the rivers. Their main mode of propagation is vegetative, though many members of this community can produce seed.
Community composition differs sharply from one haor to another, but differences among beels within a single haor are not very significant. The highest concentrations of floating vegetation are found in Hail Haor and Balai Haor, followed by Kawadighi Haor. These haors are shallower and more enclosed than Tangua Haor, Gurmar Haor, and Hakaluki Haor where lower concentrations are found. The reason for this may be the relative shallowness and moreover the closed surroundings of the high-concentration haors, which restrict advection of the plants away from these systems.
3. Rooted floating
These plants root deeply in the soil and float leaves and flower on the water surface. To accomplish this, most plants have very long stalks for both leaf and flower, and a stem that remains under water, sometimes beneath the soil; a few plants have long stems rather than long stalks. This community is one of the most dominant in the haors. It is comprised of about 15 plant species (Table D.1). The most dominant families in this community are Nymphaeaceae and Menyanthaceae. At the species level Nymphaea stellata, (nilshapla), N. nouchali (sada, raktoshapla), Nymphoides cristatum (chandmala), N. indicum (panchuli), and Trapa maximowiczii (singra, paniphal) are the most abundant and common in all the beels.
Like the other wetland plant communities, these plants are also susceptible to seasonal water level fluctuations. In the permanent beels they can survive and regenerate for the whole year. But in seasonally flooded areas, the rhizomes or seeds remain buried under the soil during the dry season and then start sprouting with the arrival of water. As water levels increases, they then elongate their stems or leaf and floral stalks. They typically start flowering on a large scale when the water starts receding just after the peak flood. Almost all the plants of this community can propagate vegetatively as well as sexually.
Community composition also differs from haor to haor and even among beels within an individual haor system. Hail Haor has the most unique vegetation pattern of this type: Nelumbo nucifera (padma) and another unidentified Limnophila species are found there and are totally absent from the other sites. Moreover, Euryale ferox (makhna) which is abundant in this haor is very rare in all the other systems. Balai Haor also has extensive rooted floating vegetation coverage, mostly Nymphaea and Nymphoides. Murir Haor has a community similar in composition but less extensive. Kawadighi Haor's community is mainly composed of a grass, Echinochloa colonum (parua). Hakaluki Haor has abundant vegetation of this type near the haor but little in the haor itself. Tangua, Gurmar Haor, and Maijeil Haor have this community but it is less prevalent.
In Hail Haor and somewhat in Hakaluki Haor, differences between beels within a single haor system are very prominent. In the other haors, it is not very significant.
4. Sedges and meadows
This is an ecotonal type (transition area between two communities, such as forest and grass land, and as such usually exhibiting competition between species common to both) consisting of amphibian plants (plants that can tolerate wet or dry conditions). Usually, the leaves of these plants are exposed to the air and the roots remain under water, though inundation and desiccation are tolerated to some degree. This community has the highest species diversity of all the haor types, with at least 35 different species present (Table D.1). In this sense, it is one of the most important plant communities in the haor area.
The most dominant families in this community are Cyperaceae and Polygonaceae, followed by Gramineae and others. At the species level Polygonum (kukra, bishkatakali, and others), Fimbristylis (joina and others), and various species of Cyperus (mutha) are most abundant and are more or less common in all the beels. Some other species like Ipomoea fistulosa (dhol kalmi), Monochoria hastata (baranukha, kechur), and Hemarthria protensa (chailla) are highly abundant in Balai Haor, Hail Haor and Gurmar Haor respectively. Most of the plants of this type are rhizomatous and can propagate vegetatively, but all of them produce seed as well.
Generally this vegetation type occupies the water margin. At the end of the dry season, this is the margin of the beels. As water levels increase during the wet season, the community in a particular spot is gradually submerged; new growth 'follows' the shallow water margin, and at the peak of flooding the community is found at the margin of the haor. Submerged individual's shoot parts die out and slowly decompose into the water, enriching it with organic matter.
Community composition varies from haor to haor, but differences among beels within a haor are not prominent; community composition seems to be particularly sensitive to the rate at which water levels increase. Hail Haor has the best community of this type, composed mostly of Cyperus and other grasses. Balai, Kawadighi, and Tangua also have good coverage but with different composition. In Tangua and Kawadighi, the community is dominated by grasses, whereas at Balai the dominant species are Polygonum and Ipomoea. Murir and Dubriar have the same composition as Kawadighi but lower concentrations. Gurmar Haor displays co-dominance of grasses and Polygonum. Erali has very little vegetation of this type.
5. Floodplain grassland
Floodplain grassland prefers reasonably well-drained land affected by flooding of fairly short duration, typically found in plain lands between a haor basin and steep hills. The community consists of various medium to high grasses. The most dominant species is Vetiveria zizanioides (binna), which in the extreme case can be virtually the only species present. Other associated species are Phragmites karka (khagra, nol), Saccharum spontaneum (khag), Sclerostachya fusca (khuri), and Arundo donax (baranol). Small annual grasses, herbs, and Cyperus are common in the dry season. The presence of tree seedlings and scattered older trees suggests that the grassland community may not be a climax type, though the succession process seems to be very slow. Formerly this was a key habitat for rhinoceros and other large mammals; in addition, a number of small bird species, some extant and some already extinct in the region, depend fully on it.
6. Reed swamp
Reed swamp (panjuban) is adapted to lands intermediate in height between the haor basin and homestead lands (kanda), typically on ridges out in the haors. These areas are fairly deeply flooded during the flood season and dry out during the dry season. The grasses Phragmites karka (khagra, nol) and Saccharum spontaneum (khag, aisha) predominate. Some sedge/meadow grasses are also found here, in lesser amounts, such as Vetiveria zizanioides (binna, gandhabena, Sclerostachya fusca (khuri), and Arundo donax (baranal, gobanal). Other than the grasses, woody shrubs like Ficus heterophylla (bonolat, baladumur), Asparagus racemosus (satamuli, hilum), and Lippia javanica (bhuiokra) are the more common species. Rosa involucrata (gunja kata), believed to be globally threatened, finds natural sanctuary in pristine reed lands. Another prominent species is Asclepias, a climber from Asclepidiaceae family. Mature reeds attain heights of six to seven meters, in earlier times affording important habitat for Single-Horned Rhinoceros, Barashinga, Bengal Tiger, and Asian Elephant.
The community is composed principally of perennials, making it particularly vulnerable to utilization pressure. Sustainable harvesting is possible if a rotation of at least three years is allowed, but reclamation of land for agriculture, indiscriminate reed cutting for building material, industrial raw material, and fuel, in particular for lime-burning, has all but eliminated the once vast reed lands of the region.
7. Fresh water swamp forest
Fresh water swamp forest consists of flood-tolerant evergreen trees. A fully-developed stand exhibits a closed canopy with mature trees standing ten to twelve meters tall. Barringtonia acutangula (hijal) and Pongamia pinnata (koroch) occur in varying proportions to form this vegetation type. Crataeva nurvala (barun), Trewia nudiflora (gotagamar, panidumur) and Salix tetrasperma (bias, panihijal) are frequently also present. These trees mostly produce their seeds in the monsoon period and they disperse them through water; ; seedlings grow in great quantities. In addition, woody shrubs such as Phyllanthus disticha (chitki), Ficus heterophylla, Rosa involucrata, and Asclepias climbers are found.
Swamp forest is adapted to monsoon flooding for three to four months, to depths of 0.5 to 2.5 m; thus, much of the area now under monsoon rice would once have been occupied by swamp forest. Remnant forest patches are now restricted to areas sloping away from village highland down towards the haor, helping to shelter homesteads from wave erosion; to elevated ridges between beels; and to stream levees. These patches currently vary from a few plants to several hectares of more than a thousand trees. Depending on local conditions, particularly the extent of human disturbance, the luxuriance of the vegetation varies, from sparse low trees with undergrowth grasses, as at Rangchi and Rupnagar in Tangua Haor, to dense closed canopy with poor undergrowth, as at Pashua Beel in Gurmar Haor.
Rangchi within Tangua Haor has an area of about 3 ha. The density is 300 trees per hectare and average breast girth is 110 cm. At Pashua Beel in Gurmar Haor and at Nurpur in Johlbhanga Haor, the density is nearly 600 trees per hectare, and average girth is 30 cm. The principal trees of these forests are Barringtonia and Pongamia.
A detailed account of the status and distribution of these forest patches type does not exist. Some larger patches are listed with the revenue officers of the districts; these are leased out, mostly to jalmohal owners who use the branches for fish entrenchment. Swamp forest has been so nearly eradicated that a recent analysis of the dendrological regions of Bangladesh, carried out in association with the FAO land resource appraisal for agriculture (1988), could state that all areas inundated for most or all of the wet season are unsuitable for any tree species. Admirably, the Bangladesh Forest Research Institute quickly corrected this impression in Trees for Lowlying Areas of Bangladesh (Alam et al., 1991).
Traditionally, forests were managed communally to provide protection of village highland from wave erosion; coppices were harvested in three years' rotation for fuel wood, housing posts, and fish entrenchment (katha). One or two branches per year can be taken on a sustainable basis. In recent years, however, outsiders (typically a jalmohal lessee) have taken control, increasing the frequency of the coppicing and the number of branches. In 1992 at Rangsi this reached tragic levels: virtually all the branches were taken from all the trees. Some of the trees may survive, if they are allowed to recover for several years.
Under sustainable management, yields of Tk 40,000 per year are possible; coppicing can begin when trees are five to seven years old, and natural regeneration is good. The upper limit of population density in mature stands is about 400 trees per hectare and the market value is Tk 30 to 50 per branch.
8. Crop field vegetation
This is a disturbed community, composed of both wetland plants and smaller dryland herbs found in other communities also. Community composition depends on the degree of waterlogging in each particular field. Cyperaceae is the dominant family in this community; a large number of other, unrelated plant families, ranging from Amaranthaceae, Euphorbiaceae, and Compositae to Gramineae are also present.
In this setting, these plants are weeds and are destroyed by farmers. These plants survive in this hostile setting by surviving unfavourable periods and multiplying rapidly.
9. Homestead vegetation
Homestead vegetation is a very important plant community, though a synthetic one. The community includes two types of plant: those cultivated for their economic value, and those that are self-propagating. Plants of the first category can be found all over the country, and composition within this type is more or less uniform. The composition within the second type is more interesting, in that it reflects the composition of nearby natural communities, including communities and species that have otherwise vanished locally, and contains some strong clues as to local vegetation composition in times past. Homesteads around Hakaluki Haor, the study site closest to the hilly rain forest, has the largest number of trees of this type. Sunamganj homesteads contain more Barringtonia, Pongamia, and Trewia trees than Moulvibazar homesteads, which suggests that the swamp forest was much more prominent in Sunamganj than in Moulvibazar.
3.3.4 Plant utilization
Currently utilized wetland plant products and services are grouped as follows (after AWB, pers. comm.):
Reliable quantitative information is not available for most of these products and services. In the few instances where order of magnitude estimates are possible and useful, these are presented below. This would include amounts currently harvested per unit area, extent of utilized area, unit price, and unit cost of collection and processing, and so on. Additional study is clearly required, focusing on the items of greatest current and potential importance.
Starch (energy) foods (FS)
During times of scarcity, local people eat grains of Oryza rufipogon, (jhara dhan), Echinochloa colonum (parua), Eleocharis dulchis (panichaise), and Hygroryza aristata (phutki). Rhizomes of Aponogeton (ghechu) and Nymphaea (nilshapla, sada, raktoshapla) are also eaten. Seeds of Euryale ferox (makhna) and Nelumbo nucifera (padma) are eaten raw or roasted. The seeds of Ottelia alismoides (panikola, kaorali), Nymphaea stellata (nilshapla) and Nymphaea nouchali (sada, raktoshapla) are made into puffed grain by frying, and may be eaten in this form or prepared into confectionery.
Trapa maximowiczii (shingra, paniphal) produces a nut which is commercially sold in both local and urban (Dhaka) markets.
Other foods (vegetables) (FV)
The stems and leaves of various plants are eaten as vegetables: this would include Alternanthera sessilis (haicha, sachishak), A. philoxeroides (helencha), Ipomoea aquatica (kalmi shak), Colocasia esculenta (kachu), Xanthium indicum (ghagra, khagra), Centella asiatica (thankuni), Amaranthus spinosus (kata note), Chenopodium ambrosoides (chapali ghash), Enhydra fluctuans (helencha, harhach), Mersilea quadrifoliata (sushnisak), and Aponogeton (ghechu).
Nymphaea and Ottelia alismoides floral stocks are also eaten as vegetables.
Eichhornia crassipes, Monochoria hastata, Nelumbo nucifera, Sagittaria sagittifolia and Limnophila are used as vegetables in many other countries, but not much in Bangladesh.
Fodder and forage (FP)
Most wetland plants can be used as food for livestock. Most of the grasses such as Hygroryza aristata, Oryza rufipogon, Panicum paludosum, Echinochloa colonum, Setaria glauca, Cynodon dactylon, Pseudoraphis, Arundo donax, Eleusina indica, Paspalum are extensively used as fodder. The members of Cyperaceae family are also used.
In the monsoon, when grass is less abundant, the major source of cattle food becomes Eichhornia crassipes, Nymphaea, and Nymphoides; other smaller herbs are also used.
Local people use many wetland plants as medicine. Polygonum is well-known for its antibacterial effect.
Another well-known species is Eclipta alba, which is used as a hair tonic.
Limnophila indica is used as an antiseptic; is mixed with coconut oil to make a liniment for treatment of elephantiasis; and is used in the treatment of certain types of fever, when the plant's juice is rubbed on the body of the patient.
Nymphoides indicum is used to treat fever and jaundice.
Nelumbo nucifera is used as a cardiac tonic, diuretic, scyptic, and antipyretic; the seeds are used as a cooling balm in skin disease; and seeds are also given for piles and ringworm.
Monochoria hastata is used against diarrhoea and dysentery, and as an aphrodisiac.
The flowers of Nymphaea nouchali are used to treat bloody dysentery and in gynaecological complaints; the powdered rhizome is used to treat piles, dysentery, and dyspepsia.
The flowers of Nymphaea stellata are used in preparing a cardiac tonic.
Cyperus tubers are regarded as tonic and stimulant.
Pistia stratiotes are used to treat diarrhoea, skin disease, gonorrhoea, syphilis, and others.
Ottelia alismoides and Ipomoea aquatica are used against haemorrhoids.
Phyllanthus is utilized as an abortifacient and diuretic.
Alternanthera sessilis, Scirpus and Rorippa indica have antidiarrhoeal activity.
Spilanthes acmella is used against toothache.
The juice of Heliotropium indicum is used in leprosy.
Cynodon dactylon, Utricularia, Sagittaria, and others are also used.
Thatching and mat-making (FB)
The grasses which are used in the Northeast Region as thatching material and to make protective screens around homesteads are Selerostachya fusca and Vetiveria zizanioides. The latter species is also a very good soil binder.
An highly-prized mat known as sithal pati is made from Clinigyne dichotoma. A 1.5 m x 2 m mat sells at times for Tk 15,000 (about US$400). This is the basis of an important cottage industry.
Barringtonia and Pongamia are exploited for homestead construction and for fuel wood.
All the grasses are dried and used as cooking fuel.
Other plants such as Ficus heterophylla, Ipomoea fistulosa, Lippia javanica and reeds are also used extensively as fuel.
Barringtonia and Pongamia forest is considered very effective in protecting homesteads from wave erosion and storm damage, which are common problems around the haors and larger beels during the monsoon. A number of the remaining forest areas are managed by local community management groups for this purpose.
Wetland vegetation makes a number of key contributions to the openwater fishery: providing shelter for the juvenile and adult fish; providing food in the form of periphyton on the stems and leaves of submerged vegetation; and supporting the base of the food chain through decomposition of plant material in the water.
The branches of Barringtonia are considered by local fishing folk and fisheries lease holders alike to be essential to fish production, indeed vital for the sustainability of the openwater fishery as a whole.
Industrial raw materials
Reeds (Phragmites karka, Saccharum spontaneum) locally known as pajuban, were intended to be an important constituent of the raw material for the Sylhet Pulp and Paper Mill (SPPM). In 1977, an estimate of the reed area available for commercial exploitation was estimated to be more than 30,000 ha, with a biomass production of 4.5 MT ha-1 (air dry basis). The present official Forest Department estimate of reed area is about 27,000 ha, but in fact there is no trace of reeds on most of it. Productivity of the remaining reeds has also decreased to an estimated 2 MT ha-1. SPPM took 22000 ha of land from the Revenue Department for reed cultivation a number of years ago, but this was unsuccessful (propagation was limited to 2000 ha only in the Chhatak, Companiganj, and Jaintiapur areas) and now the land is being returned to Forest Department management.
More than 90% of the lime requirement of the country comes from the Northeast region, and the region's lime-burning industry made extensive use of reeds as fuel, which resulted in extensive destruction. The industry now uses natural gas.
Rosa involucrata is an threatened plant in Bangladesh which finds natural sanctuary in the pristine reed lands. Conversion of reed land to agricultural use and over-exploitation of reeds for lime-burning are the main threats to the conservation of this vegetation.
Eichhornia crassipes, once considered to be a pest, is now being used as compost fertilizer in the Northeast Region (it is also used in parts of India). The ash of the plant, which contains 30% potash, 7% phosphoric acid and 13% lime, makes an excellent fertilizer; in Sudan, it increased peanut production by over 30% (Maltby, 1986).
Other soft aquatic herbs can also be used in compost: for example, Azolla is used as an important bio-fertilizer all over the world.
Pollution abatement (PA)
Aquatic plants are proving an asset in the treatment of sewage and polluted water. Lemna can remove 50% of nitrogen, 67% of phosphorous, and nearly all the heavy metals from the water. Calcutta's sewage has undergone natural purification in the complex of wetlands east of the city for at least 50 years; the facility also supports a rich fishery.
In Madras, Eichhornia crassipes is being used to clean tannery effluents that would otherwise contaminate groundwater.
In Malaysia, the aquatic plant Azolla is being used to treat wastewater both from sugar refineries and from a rubber processing plant.
In the U.S. (Maltby, 1986), Phragmites, Arundo donax and Salix sp. have been shown to filter sediment load from dredged material.
Another possible use of Eichhornia crassipes, Lemna, Nymphaea and so on is to production of biogas. Up to 40 litres of gas can be produced from 100 kg fresh weight of plants. By-products of biogas production can be used as fish feed.
3.3.5 Threatened communities and species
The freshwater swamp forest (Barringtonia acutangula, Pongamia pinnata, and Crataeva nurvala) is the native vegetation of much of the region and indeed of much of Bangladesh. It has disappeared from the country except for the small patches remaining in the Northeast Region, plus individuals surviving on homestead lands throughout the country.
The reed lands have also been reduced to remnant areas, and will likely disappear unless action is taken. In particular, Rosa involucratagunja kata, a wild relative of the garden roses, was abundant in the reed lands of Bangladesh. It was abundant in the northern districts a century ago. This plant is now rare as a result of the destruction of reed land habitat. It is now restricted to the undisturbed haors of Sunamganj.
Euryale ferox makhna and Nelumbo nucifera padma, both rooted floating plants, are also threatened. They are found only in Hail Haor now.
The major causes of decline of these plants are conversion of wetlands for paddy cultivation, increasing cropping intensity, and the increasingly intensive tillage required by HYVs which disturbs the seed banks of wild vegetation.
3.4 WETLAND BIRDS
The ornithology surveys (main and monthly) were undertaken to determine the current status and abundance of waterfowl and wetland-dependent birds occurring in the wetlands of the haor basin, and to understand seasonal changes and events. Wetland-dependent birds are those that depend ecologically on wetlands; this category would include the two fish-eagles, the Osprey, several kingfishers, and a number of marsh-dwelling passerines. Of less interest were the many other bird species that frequent the wetlands but are not dependent upon them; this category would include various birds of prey and many of the small birds typical of homestead forests and gardens.
The present status of the 125 species of waterfowl which are known or thought to have occurred in the wetlands of the Northeast Region, and a summary of the observations of the 89 species that were recorded during the present surveys, is presented in Annex D. (Eighty-seven species were recorded in the 68 wetlands, and two others, Black Bittern and Slaty-breasted Rail, were observed in rice fields).
3.4.2 Previous studies
Hume (1888) is one of the most useful early accounts of the birds of Sylhet: 178 species are listed, including Pink-headed Duck Rhodonessa caryophyllacea which is now globally extinct. Stuart Baker (1922-1930) did some work on the birds of the Northeast, which include several references to "plains of reeds", a habitat type now all but disappeared from the region. More recently, Mountfort (1969) summarized the observations of the 1966 World Wildlife Fund Expedition to West and East Pakistan. Haroun Er Rashid (1967) reviews bird species status in Bangladesh by region, one of which is the haor basin (his North-East Lowlands), but by his own admission status information is based on assumptions more than positive records, largely due to imprecise locality information in earlier accounts.
Harvey (1990), in a recent comprehensive listing of the birds of Bangladesh takes a cautious approach and includes only those species and records for which there is full documentation. The list provides a status indication for each species in each of six regions, one of which is the Northeast, plus useful information on habitat preferences and breeding seasons. The status summaries relate almost entirely to the last twenty years. The former status of species that are now rare or locally extinct is little mentioned, even though many would once have been widespread and common here. Another recent list, S.U. Sarker and K.Z. Husain (1990) included 174 bird species that occur in the wetlands and mangrove areas of Bangladesh, with a discussion of conservation implications.
There have been a few studies relating specifically to the waterbirds of the Northeast. Some preliminary investigations were carried out by Forest Department, University of Dhaka, and Bangladesh Zoological Society personnel; most of this work focused on Hakaluki Haor and Hail Haor. Annually since 1987, excepting 1989, mid-winter waterfowl censuses were undertaken in the Northeast by Forest Department and NACOM personnel in the years, as part of the IWRB/AWB Asian Waterfowl Census (see Section xx.xx). These censuses covered only four sites (Hakaluki, Hail, Kawadighi, and Tangua Haors), and the counts give only a rough indication of species present and relative abundance.
The ten site accounts in the Directory give preliminary lists of waterfowl known to occur at each site. Other useful sources of information on the birds of the wetlands of the region include D.J. Millin (1984-88, unpublished list of bird sightings at Hail Haor) and J.D. Woolner (1986-91, unpublished notes on 108 species), and Altamash Kabir (unpublished notes on scarce waterfowl in the region). Khan (1987) summarizes the status of the storks and other large waterbirds in Bangladesh and refers to the importance of the haor wetlands but few specifics. Similarly, many other recent authors refer to the importance of the haors for waterbirds, especially migratory species and several rare and endangered species, but without any useful quantitative information.
A review of this literature, when combined with the current data set, identifies a total of 125 species of waterfowl that are known or thought to have occurred in the haor basin:
Two hundred and eighty-four species of birds were recorded in the Northeast
Region during the NERP field program. A master checklist is provided in
Annex D. These 284 are grouped as follows:
The two NERP main ornithology surveys (18 Feb 92 to 12 Mar 92 and 19 Apr 92 and 9 May 92) were the most comprehensive waterfowl surveys ever undertaken in the wetlands of the haor basin. The results of the waterfowl counts are summarized by site in Figure 4 and in Table 3.4a and 3.4b; by species group in Table 3.5; and by individual species in Table 3.6.
These surveys show that despite the massive habitat losses, the haor basin remains an internationally important wintering area for migratory waterfowl, principally ducks and shorebirds. It continues to support large numbers of some resident species, notably Little Grebe, Little Cormorant, a variety of herons and egrets, both species of whistling-duck, both jacanas, Common Moorhen and Purple Swamphen. The region is also undoubtedly of some importance for passage migrants in spring, and perhaps also in autumn, at least for two shorebird species, Ruff (an early migrant) which was observed in early March and Asiatic Golden Plover (a late migrant) which was observed in late April and early May.
Waterfowl populations, main ornithology surveys
Nearly all the waterfowl were found at the fourteen principal wetland systems listed in Table 3.4a: 95% in Feb/Mar 92 and 90% in Apr/May 92. The northern haor system (Tangua Haor, Matian Haor, and Gurmar Haor complex) and Hakaluki Haor together held much the largest concentrations: about 71% (76,500) in Feb/Mar 92 and 44% (13,480) in Apr/May 92. Aila Beel also held a large concentration of ducks in late Apr 92; it was not included in the Feb/Mar 92 survey.
Feb/Mar 92 survey
A total of 108,000 waterfowl of 77 species were counted during the Feb/Mar 92 survey. This is a substantial population, but, given the vast extent of the wetlands of the haor basin, very low in comparison to other wetland systems at about the same latitude in southern Asia. There are many quite small wetlands in the much less densely populated parts of Southwest Asia (e.g. in Iran and Pakistan) which regularly support between 250,000 and 500,000 waterbirds in winter. No reliable information is available on the numbers of waterfowl wintering in the Northeast Region in the past, but there can be little doubt that there has been a drastic decline in numbers, perhaps to only a few percent of former levels. The Feb/Mar 92 survey occurred a few weeks before the spring migration, which would have peaked sometime between mid-Mar 92 and mid-Apr 92.
A total of 76,000 ducks were counted in Feb/Mar 92. If it overall coverage is assumed to be on the order of 50-75% (see Section 2.4.1), then the total number of ducks present would be about 100,000-150,000.
Most or all of the waterfowl recorded during the Feb/Mar 92 survey were birds that had overwintered in the haor basin, as little evidence for the start of spring migration was found through early March. Even so, the Feb/Mar 92 count was probably much lower than a count in December or January would have been, given the heavy hunting pressure throughout the region which would have reduced population levels.
Apr/May 92 survey
Far fewer birds (only 30,300 of 67 species) were observed during the Apr/May 92 survey, as by this time the great majority of winter visitors had departed, and the spring migration of waterfowl was almost over. At the 48 sites covered during both surveys, the total number of waterfowl had fallen from 98,850 to 21,000.
Very little breeding-related activity (showing courtship behaviour, calling, prospecting for nests sites or nest-building) was observed, though many of the resident birds had assumed breeding plumage. The only species of waterfowl which appeared to be breeding or about to breed were Little Grebe, Lesser Whistling-Duck, Cotton Pygmy Goose, Spot-billed Duck, Pheasant-tailed Jacana, Bronze-winged Jacana, Black-winged Stilt and Whiskered Tern.
The breeding seasons of waterbirds in Bangladesh are, however, known to be complex. Some species begin breeding in the pre-monsoon period; others (mainly the herons and egrets) breed during the monsoon, while yet others (for example, Little Cormorant and Oriental Darter) breed during the dry season. According to Harvey (1990), of the 33 species of waterfowl found breeding in Bangladesh in recent years, six begin nesting in March, six in April, ten in May, four in June, four in July, one in August, one in September and one in November.
Only about 20,000 of the 30,300 waterfowl recorded were resident birds and hence potential breeding birds. This is a remarkably low figure again in view of the extent of the haor basin wetlands and their obviously high productivity (illustrated by fisheries production). The other 10,000 birds recorded were winter visitors or passage migrants (for example, the flock of 7,000 Garganey at Aila Beel) not yet departed for more northerly breeding grounds.
Waterfowl populations, monthly surveys
The studies were initiated in February 1992. At this time, water levels were decreasing. Unprecedented early rains (late-March and early-April) provided water to the wetlands at Balai and raised water levels at some of the other sites (Patachatal and Erali). This probably resulted in an increase in waterfowl population which may have skewed the counts. It was subsequently established that the peak population occurs in January and that the February 1992 population was, in fact, post-peak. It was also concluded that during May and June, there was an increase in the number of species which coincided with the beginning of the southward migration of waders and other birds. The total number of waterfowl for the monitored sites in January 1993 totaled 386,000 individuals which is more than double the waterfowl thought to be supported by the region's wetlands. Monthly variations are illustrated in Annex F, Figure F-1.
In all the monthly monitoring sites the waterfowl population varied inversely with water level. The year-round monthly monitoring studies confirmed this variation. During the full monsoon, almost all the wetlands are under water. Since no habitat was available to the waterfowl, they were absent in most sites except for some at Kawadighi, Hail and Balai Haors. At these two sites, because of either embankments or drainage congestion and a reduced water discharge, the physical features appear to be changing. As a result, more vegetative cover and micro-habitat were available to both resident and migratory species.
The observations led to the conclusion that availability of cover, supported by shelter and protection increase the waterfowl population both in number of individuals and species. The number of individuals, however, was independent of the number of species. For example, some species were represented by a single individual while some numbered in the tens of thousands.
The presence of birds was also affected by human activities in the wetlands. This was well illustrated by the monthly surveys. During November and December, 1992 intensive fishing were carried out at Kuri, Erali, Kawadighi haor which involved more than one hundred people at a time. This resulted in the sharp decline in the waterfowl population, when actually the population was supposed to be reaching its peak. Again, disturbances at Tangua beel and other adjacent areas compelled the birds to move to Pashua beel and other nearby wetlands. As a result, Pashua, which is not being fished this year, had the largest aggregation of waterfowl in January 1993 of any area in the region. The numbers estimated (239,827 individuals) surpassed the total regional figures for the northeast mentioned by Scott (1989) and Scott & Rashid (1992). Similarly, because of some protection at Haorkhal, the numbers were higher but did not reach the estimated peak. This may be attributed to illegal hunting and other human activities which caused disturbances.
The monthly observations are provided in Annex F (Waterfowl Count Data). Key observations are summarized as follows:
January is the peak month for the major influx of migratory waterfowl, particularly ducks and most ducks leave by May. From April the waders start their migratory journey southwards, with the highest numbers staging in the northeastern wetlands during May/June. Waders wintering in the northeastern region start arriving as early as late-July. The water levels were at the peak during that time which forced the waders to stay at the available higher grounds.
Some of migratory birds, both ducks and waders overstayed in the northeastern region. These might be either young ones or old and sick ones but their numbers were few. Among them were Garganeys, Gadwalls, Golden Plovers and Black-tailed Godwits.
Some water-dependent waterfowls (Cormorants, Herons, Bitterns, Jacanas, Watercocks, Whiskered Terns) breed in and around the wetlands. The breeding period for Bitterns extended from April to June; Jacanas from May to August; Whiskered Terns from June to August; Cormorants from June/July to September; Herons from May/June to August/September.
Whiskered Terns were earlier thought to be winter visitors but recent studies in the region showed that they are resident birds and breed in the wetlands of the region. This is the first record of the species breeding in Bangladesh. NERP/NACOM has detailed photographic evidence of this.
Even the endangered Pallas's Fish Eagle has managed to reproduce on the limited habitat available in the northeastern region. The nests were built on old nest sites at very low heights since big and high trees are scarce. These nests measured as much as 3-4 m. Fortunately for the birds, local people were not hostile to them although there were complaints that the eagle picks up domestic chicken and ducklings. This is an adapted behaviour owing to the fact that its natural food is scarce and that since it is at the top of the food chain, it is a predator by habit.
Resident waterfowl are also affected by increases in water levels. During the monsoon period, the resident population moves to higher ground, the whereabouts of which are not yet known. This suggest that because of environmental factors, resident birds migrate locally.
Those wetlands supporting vegetation even during the peak monsoon, retained some bird population. This was supported by observations at Kawadighi, Hail, Pashua and Tangua haors. Despite physical changes in the wetlands, if birds (not all) find cover, they tend to stay for either food, shelter or nesting (e.g. Jacana, Watercock, Whiskered Tern).
Human activities such as fishing and cultivation, affects the waterfowl population in the wetlands. The disturbance caused by either human presence or activities distracts the birds. As a result, they had to increase their flight time in search of food or roosting areas. This is accomplished at the expense of energy stored in the body as fat. If the energy loss exceeds the gain the birds move to other places where the energy costs are low. This also happens during unfavourable environmental conditions such as flooding.
Threatened waterfowl species
Ten waterfowl species attributable to the Northeast Region appear on the IUCN Red List of Threatened Animals (1990; the IUCN status categories are shown in Table 3.8). For these ten species, Table 3.7 gives the IUCN (global) status, the presumed (pre-NERP) status in Bangladesh, the NERP observations, and relevant remarks. Only two of these species were observed during the NERP field studies. Table 3.7 also documents 'interesting observations', mainly observations indicating a new (regional or national) status for a species, and observations of rare and unusual species.
Several lists of bird species considered to be nationally "threatened" or "endangered" including some wetland species occurring in the Northeast Region, do exist (Annex D). Two of these lists appeared in different versions of the Draft National Conservation Strategy for Bangladesh, in the Wildlife and Protected Areas section; a third list was prepared by NACOM in 1991. All of the lists exhibit poor species choices. Some species known to be on the verge of extinction in Bangladesh are omitted, for example Black-necked Stork and Red-naped Ibis; and other very common and widespread species are included, for example Little Grebe, Northern Shoveler, and Brahminy Kite.
A national list of endangered species, consistent with reasonable criteria and developed by a committee of national experts, would be a useful tool.
3.4.5 Birds other than waterfowl
Birds of prey were found to be surviving extremely well in the region. Two species of kite were common and widespread, the Brahminy Kite as a resident and the Black Kite primarily as a winter visitor. Concentrations of over 100 kites were observed on several occasions at rubbish tips and at beels which were being drained for fishing. The White-rumped Vulture was also common and widespread. Over 150 were recorded during the Apr/May 92 survey including one flock of 80 at Kawadighi Haor. In addition to these common species, 171 raptors of 13 species were recorded during the Feb/Mar 92 survey, and 72 raptors of ten species during the Apr/May 92 survey.
Four species were observed during the Feb/Mar 92 and Apr/May 92 surveys which had not previously been recorded in Bangladesh (Swinhoe's Snipe, Red-throated Pipit, Firethroat and Black-browed Reed-Warbler) and three species of doubtful previous occurrence (Griffon Vulture, Pin-tailed Pigeon and Wedge-tailed Pigeon), as well as several species which had not been recorded in Bangladesh in recent decades. A full report on these observations is being prepared for publication in the scientific literature.
Threatened bird species (other than waterfowl)
Eight non-waterfowl species attributable to the Northeast Region appear on the IUCN Red List of Threatened Animals (1990). For these species, Table 3.7 indicates the IUCN (global) status, the presumed (pre-NERP) status in Bangladesh, the NERP observations, and any relevant remarks. Only one of the IUCN threatened species was observed during the NERP field studies.
The main reasons for the disappearance of so many wetland bird species from the Northeast Region are undoubtedly the massive conversion of floodplain grasslands and seasonal swamps to agricultural land, and almost complete elimination of swamp forest and other native floodplain forests which provide secure roosting and nesting sites for large waterbirds. Direct persecution by man has doubtless played a significant role in the demise of some species, but loss of permanent wetland habitat seems to be of less importance. Indeed, much of this habitat still remains.
On the whole, migratory waterfowl have survived better than the resident species. The migratory species are in many ways much less demanding than the resident species in that all they require is an ample food supply and secure "loafing" and roosting areas. For many of the migratory waterfowl, there remains an abundance of suitable feeding habitat and habitat loss has not been the principal problem. However, resident species require secure nests sites, free from disturbance for several months each year. Species which build their nests on floating aquatic vegetation, such as Little Grebe, the jacanas and Whiskered Tern, face no difficulties, as plenty of suitable habitat remains. The grebe and the two jacanas at least are still fairly common and widespread breeding species in the region.
However, species which nest in dense reed-beds or in rank vegetation at the water's edge, such as Yellow Bittern, Purple Heron, Spot-billed Duck, Purple Swamphen, and some of the other Rallidae, are now confined to those few large permanent wetlands or less intensively cultivated areas where such vegetation persists (such as Hail Haor, Balai Haor, Pashua Beel, and Tangua Haor). One species of extensive reed-beds and grassy marshes, the Sarus Crane, has disappeared entirely.
Cormorants, darters, pelicans, most species of herons and egrets, storks, and ibises are colonial breeders, nesting in tall trees, often in huge mixed colonies. Under natural conditions, these colonies would have existed at traditional sites in tall stands of swamp forest in the haors or in gallery forest along the river levees. It is almost certainly the destruction of these forests in the haor basin that has been the primary factor responsible for the disappearance of many of the former breeding species (Great Cormorant, Spot-billed Pelican, five species of stork, and two species of ibis) and present scarcity of some others (such as Oriental Darter). The disappearance of the White-winged Wood-Duck and Comb Duck can also be attributed to the destruction of the forests, as the former is very much a bird of forested wetlands, while the latter requires holes in large trees for nesting.
Undoubtedly, direct persecution in the form of hunting and egg-collecting combined with high levels of disturbance have contributed to the decline of many of these species. Wherever waterfowl are totally protected from hunting, they rapidly become extremely tame, and are able to utilize wetlands which in the Northeast Region would be far too heavily disturbed. A good example of this can be seen at Dhaka Zoo, where in winter as many as 10,000 ducks can been seen on the small, artificial lake inside the perimeter fence. A similar concentration of ducks occurs on the small lake in the grounds of Calcutta Zoo, while at New Delhi Zoo, there is a large breeding colony of Painted Storks within a few yards of the thousands of people who visit the zoo every day.
The bird community to have suffered the worst as a result of habitat loss in the haor basin is that which relies on the floodplain grasslands. These grasslands, with tall stands of elephant grass interspersed with marshy pools and wet meadows, must once have been very extensive in the basin, but have now been totally converted into rice fields or grazed almost bare by domestic livestock. Only one species of waterfowl, the extinct Pink-headed Duck, seems to have been dependent on this habitat type. However, at least twelve species which are typical of this habitat and which are known or thought to have occurred in the Northeast Region are now either very rare or extinct in Bangladesh. These include: Swamp Francolin Francolinus gularis, Bengal Florican Eupodotis bengalensis, Australasian Grass Owl Tyto longimembris, White-tailed Bushchat Saxicola leucura, Jerdon's Bushchat Saxicola jerdoni, Swamp (Long-tailed) Prinia Prinia burnesii cinerascens, Large Grass-Warbler Graminicola bengalensis, Bristled Grass-Warbler Chaetornis striatus, Marsh Babbler Pellorneum palustre, Jerdon's Moupinia Chrysomma altirostris, Black-breasted Parrotbill Paradoxornis flavirostris, and Slender-billed Babbler Turdoides longirostris. The present surveys failed to locate any of these, although there are single records of two species, Jerdon's Bushchat and Marsh Babbler, in the Northeast in recent years (Harvey, 1990).
Despite these dramatic losses in its avifauna, the haor basin still continues to support a wide variety of bird species, many of which are very common. Most of these species have survived because they have been able to adapt to, and in some cases benefit from, man's changes to the environment. The dominant birds of the cultivated plains and homestead forests are those species which can live alongside man, and several have become true commensals, now being almost confined to man-made environments (e.g. House Crow, Common Myna and House Sparrow). The homestead forests, in particular, constitute a rich and varied habitat with a great diversity of bird species. Most of these were originally birds of open woodland and forest edge, although a few species more typical of true forest are able to exist in some of the denser stands. In general, however, the species which have been able to adapt to these man-made environments and live in close proximity to man are the commonest and most widespread species in the Subcontinent, and thus of no conservation concern.
Amongst wetland birds, those species that have been able to switch from natural grassy marshes to rice fields have been very successful. Several of these, notably the weavers and munias, are seed-eaters, and can become serious pests in the rice crop, while others, such as various species of wagtails, pipits and warblers, are insectivores and are probably beneficial to the farmer. A number of waterfowl have also been able to take advantage of the rice fields, and most of these remain common. Those species most frequently observed feeding in this habitat included Indian Pond Heron, Cattle Egret, Little Egret, Lesser Egret, Asiatic Golden Plover, Grey-headed Lapwing, Temminck's Stint, Pintail Snipe, Common Snipe, Marsh Sandpiper and Wood Sandpiper. The two snipe and the Wood Sandpiper were particularly common, and for these species, the rice fields of the haor basin may now constitute a very important wintering area. Several species of ducks feed in rice fields at night, particularly the two whistling-ducks, and Openbill Storks will also utilize this habitat. However, even in disturbance-free areas, most large waterbirds seldom visit rice fields, presumably because of the absence of suitable food items.
Most other wetland birds have been able to survive in the haor basin either because they are migrants, moving to less densely populated regions further north to breed, or because they have been able to utilize the small remnants of natural or near-natural vegetation which persist in areas of "waste" ground, on abandoned plots, or on "marginal" land which has not as yet been brought under cultivation or human settlement. Only in Tangua Haor, Matian Haor and Gurmar Haor complex in the north are there sufficiently large tracts of relatively undisturbed wetlands to support the less adaptable species, and several species are now almost entirely confined to this part of the basin.
One group of birds which seems to be surviving extremely well in the haor basin are the birds of prey. Birds of prey are generally regarded as good indicators of "environmental health" because of their position at the top of the food-chain. Any serious build up of harmful pesticides and other bio-accumulative pollutants in natural ecosystems is quickly reflected in a rapid decline in the number of birds of prey. It seems likely, therefore, that excessive use of harmful pesticides is not as yet a serious problem in the Northeast Region. In the future, populations of these species could be monitored as indicators of pesticide contamination levels.
It rapidly became apparent during the surveys that a major limiting factor for many waterfowl species in the Northeast Region was not so much a shortage of wetland habitat per se (i.e. habitat where birds could find sufficient food) but a shortage of undisturbed habitat where birds could feed, "loaf", and roost in peace. This was particularly important for the ducks which, because of heavy hunting pressure in the region and probably elsewhere in the flyway, are very wary of humans. At most of the larger beels, intensive fishing activity in Feb/Mar 92 was causing constant disturbance to waterbirds, while at many of the smaller beels, the presence of large numbers of farmers in the rice fields surrounding the beels precluded their use by many waterfowl species. As noted above, it was at those beels which were being protected from fishing during the 1991/92 season that some of the largest concentrations of ducks were observed, for example at Chatla Beel, Aila Beel, and Pana Beel.
Heavy hunting pressure is clearly an important factor in limiting the distribution of waterfowl in the region through the direct disturbance which it causes. This is especially the case with shooting, which reinforces the wariness of the birds and prevents them from utilizing areas with high densities of humans, whether or not they are hunters. However, the impact of hunting on waterfowl populations through direct mortality (hunter kill) is less clear. Shooting may not have a significant impact, as there are relatively few hunters with guns, and their efficiency would appear to be low. A more important factor may be the effects of constant disturbance on the species' energetics. Birds which are spending much of their time on the wing, avoiding hunters and other forms of disturbance, have less time to feed, and may, by the end of the winter, be in poor condition. This could lead to reduced survival during the northward migration in spring and reduced breeding success. A series of weights of netted or shot birds throughout the winter, compared with weights of birds at totally protected wetlands (e.g. at the Bharatpur Sanctuary in Rajasthan) might throw some light on this matter.
While the number of waterfowl shot might be relatively small, the number of waterfowl caught in flight nets would appear to be substantial. Flight-netting occurs in all the main areas for wintering waterfowl, and is very common. The mere fact that one hunter had 80 live birds in his possession at one time suggests that this form of hunting birds for human consumption is a particularly deplorable hunting technique, since it is likely to kill scavengers of dead fish indiscriminately. Birds of prey such as Brahminy Kite, Black Kite, Pallas's Fish-Eagle and Grey-headed Fish-Eagle are particularly at risk. There is also, of course, the possibility of harmful effects on the consumers of the dead birds. There have been numerous cases of severe food-poisoning resulting from the consumption of poisoned birds, one of the most famous being at a banquet for participants in a conference on wildlife management and sport hunting in Iran in the 1960s. (The speciality on the menu was Chukar Partridge, which subsequent investigation revealed had been "hunted" by poisoning springs).
As a basic tool for conservation management, there is a need for a well-reasoned and officially-recognized list of nationally-threatened birds and other wildlife in Bangladesh, based on well-formulated criteria and representing a consensus of opinion. This might best be achieved through the establishment of a panel of experts including representatives of relevant Government departments, academic institutions and NGOs.
The present study focuses on mammals, amphibians, and reptiles. Wildlife, in a literal sense, refers to all organisms living in a natural state. Wildlife, in a restricted sense, always includes to wild terrestrial vertebrates, and may include other organisms depending on the context. A typical definition is that provided by Article 2, Bangladesh Wildlife (Preservation) (Amendment) Act, 1974: "any vertebrate creature, other than human beings, fish, and animals of usually domesticated species, and includes the eggs of birds and reptiles". More recent usage has tended to be more inclusive, of e.g. vertebrate pests and butterflies.
3.5.2 Previous studies
Most of the old documents, of which the District Gazeteers are most noteworthy, described some part of the Greater Sylhet district as an important fishing and hunting ground. Mitra (1957), Mountfort and Poore (1967 and 1968), Kanjilal (1934), Savage (1970), as well as Savage and Ali (1970) have described various aspects of the biological resources and their habitat in the North Eastern part of the country. Khan (1982), Scott (1989) and Ali (1990) described the freshwater wetland system in more detail.
In the fourth century, Ibn Batuta travelled through Meghna River and its distributaries while moving from Sonargaon to Sylhet. During his journey by boat, he described that most river banks and marshes were dominated by densely populated cluster villages, hats, and bazars.
These and other old documents report that human population was dense and that village settlements in the high lands (kandas) were clustered and primitive. The antiquity of human habitation is also indicated by the Behli family in Shanir Haor, who claim family history in that location extending back 1500 years or so. The conflict between the larger wildlife and human beings has likely long been acute due to the limited terrestrial habitat in the haor system during the monsoon.
3.5.3 Species observed and species groups
A checklist of mammalian, amphibian, and reptilian species known or thought to be present in the region, now or in the past, is provided in Table D.2, Annex D. For each species, this table reports the systematic, English, and Bangla names; IUCN status; CITES status; Wildlife Act status; and, for species thought to be present currently, the observation type leading to the entry (animal seen, field sign seen, recently captured live specimen examined, reported to NERP by local observers, literature; presumed present).
Overall, 89 species in 37 families are thought to have occurred in the region. Of these, 78 species in 32 families are still present; 31 are mammal species, 35 reptile, and 12 amphibian.
3.5.4 Threatened and commercially threatened species
A full 35% of the regional mammal, reptile, and amphibian species are either extinct, threatened, or commercially threatened. Almost all of the threatened species fall into one of three broad groups: large ruminants; the larger predators; and commercially valuable species - mainly turtles, but also lizards, otters, Indian Pangolin, Bull Frog, Hispid Hare, Freshwater Dolphin, and Rock Python.
Eleven species (12% of the regional species total) are regionally extinct: Leopard, Tiger, the three rhinoceros species (Sumatran Rhinoceros, Javan Rhinoceros, and Great Indian Rhinoceros), Pygmy Hog, Wild Boar, Gaur, Wild Buffalo, Swamp Deer, and Marsh Crocodile. Eight of these species are classified by IUCN as (globally) Endangered, and two as Vulnerable (Gaur, Marsh Crocodile). Wild Boar survives in domesticated form.
Of the species thought to be present, a total of nine are classified by IUCN as threatened. Two are classified as Endangered (Hispid Hare, Asian Elephant), two as Vulnerable (Rock Python, Freshwater Dolphin), four as Indeterminate - known to be either Endangered, Vulnerable, or Rare (Bengal Fox, Spotted Pond Turtle, Sylhet Roof Turtle, Yellow Common Lizard), and one as K meaning status uncertain (Smooth Indian Otter). All of these species except for Bengal Fox and Sylhet Roof Turtle are also listed under CITES Appendix I or II.
A further eleven species, not classified as threatened by IUCN, are listed under CITES Appendix I or II: Indian Pangolin, Common Otter, Small Indian Civet, Jungle Cat, Fishing Cat, Common Roof Turtle, Ganges Soft Shell, Peacock Soft Shell, Flapshelled Spotted Turtle, Bengal Grey Lizard, Bull Frog. Finally, two species (Malayan Box Turtle, Bengal Eyed Turtle) are expected to be given Commercially Threatened classification in the next edition of the IUCN Red Book.
3.5.5 Wildlife utilization
Six major uses of wildlife and their by-products were identified:
Freshwater turtle meat is widely used as source of protein in the study area. In most of the wetlands, the temporary dry season fishing camps (khola) are built near the water bodies. Most of the fishermen living in these camps regularly consume turtle meat which they catch from the water bodies. In addition, lease holder of some of the water bodies enter into a contract with the turtle collectors to provide them with the live turtles. Resident fishermen also trap turtles throughout the year -- either for their own consumption or to sell in the market. In total, about 35 turtle markets operating twice a week were identified in the area. The Shantals, Khasias and Hindu communities consume turtles as food, for medicine and for other religious occasions. The species consumed are Common Roof Turtle (Kachuga tecta), Brahminy Turtle (Hardella thurjii), Peacock Soft Shell Turtle (Aspideretes hurum), Spotted Pond Turtle (Geochlemys hamiltoni), and Spotted Flapshell Turtle (Lissemys punctata).
The remains of turtles found near human habitations indicate that the group was part of man's diet for centuries (Das, 1985). Today turtle flesh is consumed by a great many communities throughout the world. Sometimes as a source of protein and sometimes as a luxury food. A survey of restaurants in various countries indicates that freshwater turtles top the list of the 10 most popular meats.
Other wildlife consumed as food includes snakes and porcupines. All snake species and porcupine available in the wetlands are consumed by ethnic minority people.
A total of eleven species of reptiles and mammals are used to treat diseases of both humans and their domestic animals. The most common uses are extracts of oil from turtles, dolphins, lizards, snakes and even from the jackal. The oil is used to treat rheumatic fever, respiratory diseases, asthma, skin diseases, and as a preventive against colds. Some of the by products from Porcupine quills, extract from lizards and turtles are also believed to have aphrodisiac values.
In India, the flesh of the flapshell turtle is prescribed as a cure for tuberculosis. Charaka, the ancient Hindu physician, recommended turtle meat in case of indigestion, weakness of body and they have been used by the Chinese since at least 2737 B.C. It is in China where the greatest number of turtles are used for medicinal purposes.
In Manikganj and in some part of Chittagong, the turtle's carapace is burned to ash and this ash is commonly used to treat the skin diseases of cows and buffalo as well as burns to humans. Venom from the krait and cobra are used by gypsies (bede) in the region to cure various chronic diseases.
Frogs and turtles from the wetlands were a most important non-traditional export commodity for Bangladesh. Between 1974 and 1987, the country earned Tk 315,170,000 by exporting live turtles (Source: Export Promotion Bureau). In today's commercial world, most parts of the turtle have some value. The flesh is consumed, the neck and tail bones and the viscera are used in soup, the fat is needed for soups and creams, the oil forms a cosmetic base, the flipper and neck skins of the larger varieties are tanned and used to manufacture leather articles such as handbags and shoes, the shell is used for making jewellery and ornament cases. Juveniles, as well as adult turtles are sold as stuffed curios to tourists in various countries, to be hung on walls for decoration. The tortoise-shell is one of the most expensive animal products -- weight for weight, it is more valuable than ivory. In 1977 alone, India exported more than 82,000 kgs of raw tortoise-shell.
A review of Japanese Customs Statistics indicate that Bangladesh (then East Pakistan) first exported monitor lizard skins to Japan in 1958. In that first year, 4000 kgs of skins were exported and in the next two successive years, 40,000 kg and 65,000 kg of skins were exported. During the period from 1971 to 1987 Bangladesh exported 445,946 kg of monitor lizard skins to Japan (Khan, 1988). Despite the ban on export of lizard skins, a large quantity are smuggled out of the country. In 1988, Traffic Japan reported that Japan imported the skins of 730,000 endangered lizards from Bangladesh (Khaleej Times, Sept, 2, 1988).
Between 1972 and 1987, bull frogs were one of the major export commodities of Bangladesh. A considerable numbers of frogleg processing plants were established in the Chittagong and Khulna areas. It has been reported that on an average, Bangladesh exports the legs of 70 million frogs per year (Choudhury 1986). It was also noted (Ali 1985) that 3-4000 tons of frog legs were exported from India annually.
Skins of snakes, cats, mongoose, and otters are also used in trade. Venom extracted from poisonous snakes is a very valuable raw material in the preparation of antivenom serum and is also widely used in antirheumatic diseases.
Otters, mongoose, and turtles are used as pets and as captive animals for various purposes. Trained otters in southwestern Bangladesh are widely used by fishermen for herding fish into their nets. Raising and training these otters is also a profitable business.
Frogs and toads are used by people dwelling in and around the wetlands of the region for bait. They used frog baited hooks which attracts carnivorous fish. Each of these individually baited hooks are tied in a line which is 200-300 meters in length. Usually there are 200 hooks on the line. The frogs are hung vertically, hooked through the vertebral column with strong nylon string, usually 0.5 m in length, just at the surface of water. The limited movement which these frogs can make causes splashing and attracts the fish.
Most of the wetland wildlife have recreational value both locally and at zoos and museums. Among the people of wetlands, numerous myths, ritual beliefs, and historic religious and cultural values exist, involving snakes, turtles, lizards, frogs, otters, and mongoose.
3.6 SEASONAL CHANGES, RELATIONSHIPS, AND EVENTS
The wetlands of the haor basin are situated in a highly seasonal environment. Temperatures in mid-winter regularly fall below 10 C, while during the pre-monsoon period they often exceed 35 C. Over 80% of the annual rainfall of about 4,000 mm falls during the monsoon season from June to October, and the region may remain completely dry for weeks on end during the winter months. Wetlands which are dry or almost completely so in late March or early April may be flooded to a depth of six metres by the end of the monsoon. During the pre-monsoon period, flash-flooding may cause river levels to rise by as much as four metres in just two or three days. These wide fluctuations in the physical conditions are reflected in the changing structure of the plant communities in the wetlands, as well as in the agricultural activity and fishing activity of the local people. These in turn affect the wildlife populations. Waterbirds, being highly mobile, are especially well adapted to these fluctuating conditions, being able to move rapidly from one region to another as feeding conditions change.
3.7 IMPACTS OF WATER RESOURCES DEVELOPMENT PROJECTS
3.7.1 Concepts and assessment methodology
It should be clear at this point that the wetlands of the Northeast Region are complicated, dynamic resource systems. It is also clear from the project monitoring, evaluation, and planning work done by NERP so far that the actual (as opposed to planned) impacts of water resources projects are complex.
Conceptually, the interaction between projects and wetlands can be represented by an n x m matrix, where n is the number of project types, or better still, types of project activities, and m is the number of wetland resource subsystems. Project types would include submersible flood protection, full flood protection, and drainage improvement. Project activities, both normal and abnormal, would include: preconstruction activities such as surveys; construction activities such as site preparation, channel excavation, and spoil disposal; operation and maintenance activities such as agricultural changes, structure operation, breaches, and public cuts; and abandonment activities (such as reclamation of infrastructure areas for other uses). Wetland resources subsystems would include the beel fishery, floodplain fishery, submerged vegetation, reed community vegetation, migratory water fowl, and resident water fowl. Not infrequently impacts on specific species would be of interest.
The value of n is at least 25 and the value of m is at least 30 (two fisheries systems, seven plant communities, roughly ten threatened animal species, and roughly ten bird species). Even supposing that 90% of the n x m potential interactions are trivial still leaves about 70 potentially significant interactions between projects and wetlands.
The n x m matrix under discussion is in fact a standard tool of environmental impact assessment. Composed of n rows and m columns, each cell of the matrix represents a potential interaction. The tool is developed and used in the context of a systematic review of potential impacts, which should be undertaken by representatives of the range of stakeholder interests and relevant technical disciplines. This is the approach NERP has been taking in the prefeasibility studies of specific proposed projects. Those interactions flagged as potentially significant are to be investigated further at the feasibility stage.
3.7.2 Quantitative model - impacts of cropping changes on wetland habitats and floodplain grazing
A key concern in many of the proposed FCDI projects is the impact of expected cropping changes on wetland habitats and grazing area. We have devised a quantitative model to predict these changes. Like the cropping change model itself, the wetland/grazing change model is driven by land type shifts. Therefore it is quantitative and fully consistent with the cropping changes, and with the engineering hydrology analysis which predicts the land type shifts.
First, we must define wetland/grazing land types in terms of the conventional land types/uses. These are:
'Winter grazing area'. Defined as higher (F0, F1, and F2) lands lying fallow in the dry winter season, plus any perennially-fallow highlands. This land would have limited residual moisture. While it is clear that animals do graze on such areas, productivity per unit area is not known.
'Winter wetland'. Defined as low (F3) land lying fallow in the dry season, plus any perennially-fallow lowland (F4), beel, and channel areas. This land would likely have considerable residual moisture and could support a range of wetland plant communities.
'Summer wetland'. Defined as summer-inundated (F1, F2, and F3) land lying fallow in the summer, plus perennially-fallow lowland (F4 area), beel, and perennial channel areas. This land would be inundated to >0.3 m and would support submerged, free-floating, rooted floating, and sedge/meadow plant communities.
The quantitative analysis is derived from pre-and post-project land type and cropping areas. An example is shown in Table 3.9.
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