Abstract: The analysis on the niche characteristics of dominant populations in Cycas fairylakea community by calculating niche breadth and niche overlap showed that the dominant populations with wide niche breadth had an entire niche overlap with other populations,whereas the populations with small niche breadth did not have a necessarily entire niche overlap with the populations of wide niche breadth.The populations with similar niche breadth had a large niche overlap,and the large niche overlap between dominant populations would cause the changes of community composition and structure,and thus,affect the development of the community because of resource competition.With the growth from understory to stand canopy,the niche overlap between two same populations changed from large to small.The larger niche overlap of C.fairylakea and mesophilous dominant populations indicated that there was a promotion between them,and no competition existed due to the difference of their plant height.Therefore,rebuilding the composition of C.fairylakea community to make the mesophilous populations be dominant ones may be helpful to recover and develop C.fairylakea population.

Key words: Biocontrol agent, Plant growth-promoting microorganism, Pesticide-degrading microorganism, Multifunctional micro-flora