Formation Background of the Zhalong Wetland and its Eco- environmental Significance
扎龙湿地的形成背景及其生态环境意义

Zhalong wetland locates at the western part of Heilongjiang province and was developed from the terminal lake of the Wuyuer river. In this paper, the geological environment of the Zhalong area and the relationships among the Zhalong wetland, the Nenjiang river and the Songnen desert were studied by field survey, soil sample analysis and remotely sensed image interpretation. It was found that the desert from Qiqihaer to Daqi consisted of NW- extended dunes and saline, forming a NE - extended dune belt with Keerqin desert together. The desert was mainly developed from the last glacial period. After that, the Nenjiang river flowed through the dune area and rebuilt the dunes and a lot of yoke lakes were left in Zhalong area. Because of the crustal tectonic uplift in the Zhalong area, the Nenjiang river moved westwards and Wuyuer river became an inner river which terminal lake evolved and developed as the present Zhalong wetland eventually. So the environmental evolution of the Zhalong area since the last glacial period was concluded as: the wind- blown dune belt formed → the Nenjiang river rebuilt the dune belt → the Nenjiang river westwardly migrated and the Wuyuer river became an inner river → the terminal lake of the Wuyuer river evolved to the Zhalong wetland. Therefore, the Zhalong wetland and the Lianhuan lake developed on an once- existed desert, suggesting that the ecoenvironment of the area is the frailest in the whole Nenjiang watershed. It means that the salinification and desertation in the area would rapidly develop and severely affect the eco- environment of the Qiqihaer- Daqi area if the Zhalong wetland disappeared.