The dynamics of soil organic carbon(SOC)decompositions and the carbon pool sizes and turnover rates of active carbon pool

slow carbon pool and resistsant carbon pool under different vegetations are discussed in the paper.The results indicate that cumulative emission of CO_2 is 1 723~5 065 mg/kg in the surface soil and 178~642 mg/kg in the subsoil from incubation data for 90 days.The general trend is that the former decomposition rate is faster than later period and in the surface soil than in the subsoil.Decomposition rate decrease in the order of silver fir

birch and mixed forest

pine forest.Under different vegetations

the size of active carbon pool from surface and subsoil respectively accounts to 0.54%~1.67% and 0.45%~5.48% of total soil organic carbon

and the mean residue time is 11~56 days and 60~88 days;Slow carbon pool

23.0%~63.3% and 33.2%~72.2%

4~70 years and 24~161 years;Resistant carbon pool

35.5%~75.5% and 26.0~65.0%;The contents of soil organic carbon

active carbon

slow carbon and resistant carbon is more in the surface soil than subsoil.The chemical composition of litter from vegetation mainly determine the content of active carbon pool and slow pool.The resistant carbon pool is mainly determined by soil clay and other physical and chemical character.