Abstract: The forest in the southern mountain area of Lanzhou is a natural ecological barrier for Lanzhou city,its area size and ecological functions have a direct impact on the improvement of air quality in Lanzhou city.On the basis of investigation and research of this forest growth and management status,according to the close-to-nature forest management technology introduced from Germany and in combination with the local site conditions,the close-to-nature management technology for natural secondary forests such as Aspen birch forest,shrub forest etc was put forward,which aimed to accelerate the close-to-nature management process of natural secondary forest,transform the low quality,low efficiency and low yield forest into the close-to-nature forest of high productivity and achieve a stable ecosystem with diverse functions.

Key words: secondary forest, introduction of objective tree species, future crop trees, close-to-nature management, mountainous area of South Lanzhou