Dong Thap Muoi
Location:	10°35'-11°00'N, 105°20'-106°00'E; between Cao Lanh Provincial Town and the Kampuchean border, in Tam Nong, Thanh Binh and Hong Ngu Districts, Dong Thap and Long An Provinces.
Area:	300,000 ha.
Altitude:	0.5- l.5m.
Biogeographical Province:	4.5.1.
Wetland type:	15, 18, 19 & 21.
Description of site:	A large area of seasonally flooded alluvial plains on the north bank of the Mekong (Tien) River near the Kampuchean border, with patches of Melaleuca forest, some permanent ponds and marshes, and areas of rice paddy. Most of the wetland is flooded only during the rainy season and dries out completely during the dry season. The floodwaters are fresh but sometimes become affected by sulphates from the soil, especially in April, May and June. Flooding commences at the beginning of July; from then until the end of January, large areas are flooded to a depth of 2m. Peak flooding occurs between late September and the end of October, when some areas are flooded to a depth of 3.38m. A major effort was made to drain the wetland during the war. Drainage ditches were dug through the marsh and the Melaleuca forests were destroyed with toxic chemicals and napalm. Drainage activities continued after the war in an attempt to reclaim the land for agricultural purposes. A complicated system of canals has now been constructed, and some areas have been converted into rice paddies and other agricultural land. However, despite the high investment of manpower and financial resources, rice production has been low because of the problem of sulphate soils. As drainage has proceeded, acid sulphates in the soil have risen to the surface, and pH levels have fallen to as low as 2.8 in some places. Attempts to reclaim those parts of the marsh with high sulphate content have now been abandoned, and some previously drained areas have been restored to their natural condition.
Climatic conditions:	Tropical monsoonal climate, with a rainy season from the end of April to November and a dry season from December to early April. The annual rainfall varies from 1,200 mm to 2,400 mm, about 90% of the precipitation occurring during the rainy season. The mean monthly temperature varies from 25°C to 28°C. Evaporation is 1,500-2,000 mm per year.
Principal vegetation:	The swamp and grassland vegetation is dominated by species such as Leptochloa chinensis, Echinochloa crusgalli, Marsilea minuta, Cyperus elatus, C. polystachys. Eriochloa procera, Eleocharis dulcis, Sacciolepsis myuros, Nelumbium nelumbo and Nymphaea sp. Most of the original Melaleuca forests were destroyed during the war or subsequently cleared for timber and agricultural land. In recent years, however, large areas with sulphate soils unsuitable for agriculture have been replanted with Melaleuca. Wild rice Oryza sativa grows naturally in the marsh, and provided an important source of food for the local people during the war. The principal tree species on the dikes are Lagerstroemia speciosa, Ficus microcarpa, Eleacarpus sp and Morinda persicacfolia. Small patches of natural forest on higher ground are dominated by species of Dipterocarpaceae.
Land tenure:	Under provincial ownership.
Conservation measures taken:	A scientific committee has recently been set up to help the local authorities develop policies for the sustainable exploitation of the natural wetland resources. In many parts of Dong Thap Muoi, drainage plans have been abandoned in favour of restoration of the wetland ecosystem and rational utilization of the natural resources. Dikes have been constructed to maintain water levels and increase pH levels, and some 30,000 ha have been replanted with Melaleuca. Several wetland reserves have been established, notably the Tram Chim Sarus Crane Reserve in Tam Nong District. This reserve was established by Dong Thap Province in 1986; its initial area of 5,000 ha was increased to 9,000 ha in 1987. Construction works have been carried out at the reserve with the objectives of restoring the ecosystem to attract various bird species, promoting scientific research, and encouraging tourists to visit the area.
Conservation measures proposed:	Further work proposed at the Tram Chim Reserve includes strengthening the dikes surrounding the reserve, installing water control structures, establishing a visitor centre and guest house, and improving conservation awareness amongst the local people.
Land use:	Large areas are used for the cultivation of a floating strain of rice which can be grown even during the rainy season. Areas with a high sulphate content in the soil are used for forestry (Melaleuca), fishing and duck rearing. Reclaimed land is used for the cultivation of rice, sugar cane, jute, fruits, ground nuts and vegetables.
Possible changes in land use:
Disturbances and threats:	The main threats to the region are encroachment by local people for settlement and agriculture, and over-exploitation of the wildlife resources such as fish, shrimp, small mammals, birds, snakes and turtles. Hunters use poisoned bait to catch herons and egrets for food, and other large waterbirds such as Leptotilos javanicus, Mycteria leucocephala and Grus antigone are occasionally killed. Wintering ducks are caught in nets and sold in the local markets.
Economic and social values:	Dong Thap Muoi contains the largest area of floating rice in the Mekong Delta. The wetland supports a major fishery, and is capable of providing a valuable forestry resource. The wetland serves as an important natural flood basin, storing water during the rainy season and reducing flooding in the more densely populated areas of the lower delta. Because of its impressive wildlife including several rare species, the area has considerable potential for scientific research, environmental education and nature-oriented tourism.
Fauna:	Dong Thap Muoi is one of the most important areas in the Mekong Delta for both resident and migratory waterfowl, and is much the most important area for the endangered eastern race of the Sarus Crane Grus antigone sharpii hitherto known. The crane was a common breeding bird in the area some 30-40 years ago, but disappeared completely during the war years and has only recently returned as a nonbreeding visitor during the dry season. Groups of 10-20 birds were observed by Vietnamese biologists in early 1985. Since then, the population has increased rapidly and each year the birds have stayed longer in the area. An estimated 400-500 cranes were present in January 1988, and over 1,000 were recorded in April 1988. Some cranes are now present all year except in September and October, when the land is deeply flooded. The largest concentrations of waterfowl occur during the winter months, as water levels are falling. A concentration of 20,000-30,000 ducks, mainly Anas querquedula with some A. acuta and A. penelope, was observed in December 1987. Other common species include Phoiacrocorax niger, Ardeola bacchus, several species of Egretta, Ardea purpurea, A. cinerea, Anas poecilorhyncha, Metopidius indicus, Himantopus himanlopus, Glareola maldivarum, Pluvialis dominica, Numenius arquata, Tringa totanus, T. nebularia, T. stagnatilis and T. glareola. The storks Mycteria leucocephala, Ephippiorhynclzus asiaticus and Leptoptilos javanicus and the ibis Threskiornis melanocephalus are regular visitors in small numbers. It is possible that the endangered White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea still exist in the area, although none has been seen in recent years. The harriers Circus (aeruginosus) spilonotus and C. melanoleucos are common winter visitors. Mammals include an otter Lutra sp. The rich reptilian fauna includes a wide variety of snakes and turtles. The dominant fishes are species of Ophiocephalus, Clarias and Anabas.
Special floral values:	One of the common marsh plants, Eleocharis dulcis, is the principal food of the Sarus Cranes.
Research and facilities:	Preliminary faunal and floral surveys have been carried out, and a detailed study of the Sarus Crane population was initiated in 1988.
References:	Karpowicz (1985); Le Dien Due (1984, 1987a & 1987b); Morris (1988b); Vo Quy (1984); Vo Quy & Le Dien Duc (1984).
Criteria for inclusion:	123.
Source:	Le Dien Duc and Derek A. Scott.