Abstract: Studies on the microoganism and biochemical activity of forest soil in different site conditions of Chinese-fir plantation were carried out in Lilou Forest Area, Longshen County, Guangxi Autonomous Region. The results indicated that there were remarkable differences in different topography and soil types. The quantity and number of colonies of predominant groups of soil microoganisms in the black sandy soil in the valley and hillside were higher than those in the yellow and red soil on the ridge. In the same case, the biochemics of soil respiration and the biochemical activities (such as ammonification, nitrification, nitrogen fixation, cellulose decomposition, protease, invertase, catalase and polyphenoioxidase) of the former were higher than those of the latter. It showed that the productivity of the former was higher than that of the latter.

Key words: Soil microorganism, Biochemical activities, Artifical forest of Chinese-fir