Abstract:

The forests of Picea crassifolia in Qilian Mountains are typical mountain forests in arid and semi arid area of west China, its unique hydrological roles lay a foundation for the steady development of oasis ecological economic systems in the corridor. In this paper, the effects and functions of the forest on hydrological cycle and rainfall distribution were summarized through the long term fixed observing and studying . The results showed that the forests could reduce the amount and intensity of precipitation and evaporation inside forests by canopy interception, which could avoid the surface runoff, soil and water loss and keep the high air humidity and soil moisture content, provide shadow environment and enough water conditions for shade plants. The air humidity of forests area is larger than grasslands or bare lands at the same height because of the forest evaporation. In addition, forests change the regional air circulation, make material preparation for precipitation and take effect in increasing rainfalls of forest areas.

Key words: Forest microclimate, Hydrological function, Arid and semi arid area, Picea crassifolia