Abstract: Ecological functions regionalization has become an important method to effectively coordinate the conflict of ecological protection and economic development, to achieve efficient management of regional ecosystems. This research chooses the middle reaches of the Heihe River as the study area. Based on the basic geographic information data, the natural geographic data and the land cover data(1986, 1995, 2000, 2010 and 2011), this research analyzes the ecological sensitivity and the importance of ecosystem services. Small subwatersheds are used as basic clustering units and ecological functions regionalization has achieved applying the two-step cluster method. Furthermore, dominant ecosystem services are identified and zoning management and ecological regulation is proposed. The main conclusions are as follows: (1)The main types of ecosystem in the middle reaches of the Heihe River are desert, grassland and farmland, the sum of the three accounts for more than 90% of the total area; Forest, water and residential area that occupied less than 10% have a sporadical distribution; During 1986 to 2010, the area of farmland reduced, increase and decreased, but the urban and rural settlements has a trend of expansion; (2) Northwest area is obviously more sensitive than southeast. The extremely sensitive area (which takes up about 24%) is distributed in the northern Zhang-lin-gao plain, the Heli Mountains, the Gobi desert front of the Qilian Mountains and the Sunan Minghua counties; The highly sensitive area( which accounts for about 58%) is mainly distributed in the alluvial diluvial plain in Hexi corridor; (3) The spatial pattern of three ecosystem services is similar, the extremely important area that occupies about 3.2% is located in the buffer of the Heihe River; The moderately important area that accounts for 20% is around the Qilian Mountains, Yanzhi Mountains, Longshou Mountains; (4) The middle reaches of the Heihe River can be divided into 3 ecological regions(including Qilian Mountains forest and glassland ecological region, the Hexi corridor alluvial and diluvial fan farmland ecological region, northern corridor fan shrub and desert ecological region) and 8 ecological function regions. Based on the dominant ecosystem services, the ecological function regions are classified as ecological protection zone, ecological coordination zone, ecological control zone, and ecosystem management tactics are proposed, accordingly. The results of the research can provide a reference for ecosystem management in the middle reaches of the Heihe River.

Key words: ecological sensitivity, ecosystem service, ecological functions regionalization, ecosystem management, Heihe River