Effects of thinning on accumulation of soil microbial residue carbon of Picea asperata plantations in sub-alpine region of western Sichuan,China
Microbial residues are an important component of soil organic carbon(SOC).It is unclear how long-term thinning affects the accumulation characteristics of microbial residue carbon(C).We analyzed the differences in soil physicochemical properties,microbial communities,extracellular enzyme activities,and microbial residue C in topsoil(0-10 cm)and subsoil(20-30 cm)in Picea asperata plantation of non-thinned(control,4950 trees· hm-2)and thinned for 14 years(1160 trees·hm-2)stands,aiming to reveal the regulatory mechanism of thinning on microbial residue C accumulation.The results showed that thinning significantly increased SOC content,total nitrogen content,available phosphorus content,the proportion of particulate organic C,soil water content,C-cycle hydrolase,and acid phosphatase activities,but significantly reduced the proportion of mineral-associated organic C.Thinning significantly affected the content of fungal and microbial residue C,and the contribution of microbial resi-due C to SOC,and these effects were independent of soil layer.The content of fungal and microbial residue C was 25.0％and 24.5％higher under thinning treatments.However,thinning significantly decreased the contribution of microbial residue C to SOC by 12.3％,indicating an increase in the proportion of plant-derived C in SOC.Stepwise regression analysis showed that total nitrogen and soil water content were key factors influencing fungal and micro-bial residue C accumulation.In summary,thinning promoted microbial residue C sequestration by altering soil pro-perties and changed the composition of SOC sources.
stand densitysoil organic carbonsoil microbesamino sugars
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