Wetlands in Saikhowa National Park

DIBRU FLOODPLAIN

Location: along a stretch of the Brahmaputra from the confluence of the Dibang and Lohit rivers downstream to the vicinity of Dibrugarh, Assam
Area: More than 100,000 ha of riverine marshes and floodplain wetlands in a strip up to 20 km wide along 80 km of river
Altitude: 90-100 m
Biogeographical province: 4.9.4 Wetland type: 11, 13,15,18,19

Description of site: A complex of wide river channels, sand banks, riverine marshes, oxbow lakes, and seasonally flooded grassland and swamp forest on the floodpLain of the Brahmaputra river downstream from the confluence of the Lohit and Dibang rivers. The Siang river enters in the north, and the Dangri, Doom Dooma, and Dibru rivers in the south. The whole area is extensively flooded during the monsoon, and there is a good supply of water, both surface and subterranean, throughout the year. There are large tracts of permanent swamp forest and seasonally flooded forest in the Dibrugarh and Saikhowa Reserved Forests between the Brahmaputra and the Dangri/Dibru rivers. Frequent changes in the course of the rivers have created a patchwork of transitional wetland and forest types, and precluded permanent settlement over much of the area

Climatic conditions: Humid, tropical monsoon climate with an average annual rainfall of 4000 mm. The winters are relatively cool and dry. Mean temperatures range from 10°C in winter to 38°C in summer

Principal vegetation: A mosaic of swamp vegetation, grassland, swamp forest, and tropical deciduous forest. Eichhornia crassipes in some of the ponds and streams

Land tenure: State-owned (Government of Assam, Forest Department)

Conservation measures taken: Most of the forest on the south bank of the Brahmaputra is included within the Dibrugarh Reserved Forest (21,000 ha) and Saikhowa Reserved Forest

Conservation measures proposed: It has been proposed that the contiguous Dibrugarh and Saikhowa Reserved Forests be designated as a Wildlife Sanctuary. The area would be suitable for re-introduction of the endangered white-winged wood-duck (Cairina scutulata) using the progeny of the captive breeding programme in Assam, but this would be dependent on the establishment of an effective Wildlife Sanctuary

Land use: Fishing in the permanent water bodies, and extensive timber operations in the forested sections. Adjacent areas are under cultivation, chiefly for rice

Disturbances and threats: Most of the forests have been heavily exploited for timber, and little dense forest now remains. Fishing activities cause a considerable amount of disturbance, and there is heavy grazing pressure from domestic livestock. Peripheral areas are being reclaimed for agriculture, and there has been a considerable amount of encroachment at the southwestern end of the Dibrugarh Reserved Forest. Much of the Reserved Forest is now under threatbecause of a natural shift in the course of the Brahmaputra river

Economic and social values: The wetland supports a large commercial fishery, and provides a reliable source of water throughout the year. Because of its great natural beauty and wealth of wildlife, the area has considerable potential for outdoor recreation and tour-ism

Fauna: The rich fish fauna includes rohu, ari, borali and a species of freshwater prawn. The mahseer (Tor sp.) a popular sport fish, is common in some of the tributaries. The area is of special importance for the endangered white-winged wood-duck (Cairina scutulata). The species seems to have disappeared from the Dibrugarh and Saikhowa Reserved Forests in recent years, but still persists in the Doom Dooma Reserved Forest to the southeast. A flock of eight C. scutulata has been observed as recently as 1985 along the Doom Dooma river bordering the south and southwest side of the Reserved Forest. The wetlands are also important for many resident and migratory waterfowl, particularly Anatidae, and a variety of freshwater turtles and mammals Special floral values: The area supports a large variety of orchid species