Abstract: With incubation test, this paper studied the effects of fine root decomposition of Alnus cremastogyne, Cunninghamia lanceolata and Michelia macclurei on the content of soil active organic carbon at 9 ℃, 14 ℃, 24 ℃ and 28 ℃. The results showed that the decomposition rate of fine root differed significantly with test tree species, which was decreased in the order of M. macclurei> A. cremastogyne > C. lanceolata. The decomposition rate was increased with increasing temperature, but declined with prolonged incubation time. Fine root source, incubation temperature, and incubation time all affected the contents of soil microbial biomass carbon and water-soluble organic carbon. The decomposition of fine root increased soil microbial biomass carbon and water-soluble organic carbon significantly, and the effect decreased in the order of M. macclurei> A. cremastogyne > C. lanceolata. Higher contents of soil microbial biomass carbon and water-soluble organic carbon were observed at medium temperature and middle incubation stage. Fine root decomposition had less effect on the content of soil readily oxidized organic carbon.

Key words: Desert plant, Biomass, Estimation, Crown characteristic