Abstract: Changes of plant diversity and composition can directly or indirectly influence soil ecological processes. Tree species traits and diversity are important driving factors for soil microbial community. Based on Biodiversity-Ecosystem Functioning Experiment China (BEF-China) in Xingangshan of Jiangxi Province, we investigated the microbial community composition in four diversity treatments (mono species, 2 species, 4 species, and 8 species) by phospholipid fatty acid (PLFA) method. Our results showed that the soil microbial community structure differed significantly among different plant diversity treatments. The microbial total PLFA increased with the increases of plant diversity from mono species to 4 species, and then decreased at the 8 species treatment. Soil properties explained 28.4% of the variation in microbial community structure, while litter properties explained 12.3% of the total variation. However, the subgroup PLFAs of microbial community showed no significant variation due to the higher heterogeneity in the forest ecosystem and the response lag of belowground ecological processes. Therefore, the effects of plant diversity gradient on the belowground subsystem are needed to be monitored in the long term, in order to accurately evaluate the relations between the aboveground biodiversity and ecosystem function.

Key words: biological characteristics, Rhizobium, legume, phage