Abstract: We used young-age Poplar-birch stands to set three thinning treatments level to collect litter decomposition rate, carbon storage of soil Layer A and Layer B and soil respiration rate, analyzed the effect of differ thinning treatments of soil carbon storage, and discussed the theory of impact of soil carbon accumulation. Thinning was helpful to the accumulation and decomposition of forest litter, leaf litter decomposition weightlessness rate average size of T₂>T₀>T₁, but at the end of litter decomposition T₁ intensity carbon to release a quantity was the largest, 34.73% of the total weight before decomposition, higher than T₀ and T₂. Different thinning intensity was not significant effect on soil carbon content in each layer, but has a tendency to increase forest soil carbon, T₁ thinning intensity of soil total carbon storage is largest and it’s Layer A of soil total carbon ratio reached 80.95%, higher than T₀ and T₂. The regression of the soil respiration rate and soil temperature relationship was not significant, but thinning changed the soil temperature with the increase of thinning intensity, and soil respiration rate had a tendency to reduce. Different thinning of sensitivity of soil respiration rate of soil temperature was different, Q10 value for T₁<T₂<T₀. Thinning accelerated the decomposition of forest litter accumulation and had a tendency to reduce the soil respiration rate, so the appropriate intensity of tending thinning achieved the aim to increase the forest carbon fixed amount.

Key words: Poplar-birch stands, thinning intensity, carbon storage, litter decomposition, soil respiration