Abstract: Seasonal variation of soil microbial biomass plays an important role in the carbon cycle of terrestrial ecosystem. To understand this variation and its main affecting factors along an elevation gradient in mid-subtropical Wuyi Mo u ntains, four plant communities at different elevation, i.e., evergreen broadleaf forest at 500 m, coniferous forest at 1200 m, dwarf forest at 1800 m, and alpin e meadow at 2100 m were selected as study sites. The study from June 2005 to June 2006 showed that there was an obvious seasonal variation of soil microbial bioma ss along the elevation gradient, and the variation under the four plant communit ies had the same trend, being maintained at a high level in early spring but at a low level in summer. Soil microbial biomass had significant correlations with soil available organic carbon and soil moisture, but less correlations with soil temperature, soil total organic carbon and nitrogen, and plant litterfall input , suggesting that soil available organic carbon and soil moisture were the main factors controlling the seasonal variation of soil microbial biomass in the fore sts of Wuyi Mountains.

Key words: Allelopathy, Wheat, Cucumber, Radish