土壤水分对黄土高原温性草原凋落物分解及土壤有机碳形成的影响OA

Litter decomposition is a key process affecting the formation of soil organic carbon(SOC),and soil moisture conditions exert a significant influence on this process.Investigating the effects of soil moisture changes on grassland litter decomposition and its role in soil organic carbon formation is conducive to clarifying the dynamic changes in soil carbon pools and their stabilization mechanisms in the context of climate change.In this study,Stipa bungeana,a dominant species in the temperate grasslands of the Loess Plateau-was selected for study.S.bungeana leaves(SL)and S.bungeana roots(SR)were co-cultured with soil for 3 years under different moisture conditions[W1:annual average soil moisture content(gravimetric water content of 7.16％);W2:50％of soil field capacity(gravimetric water content of 23.55％)].The decomposition characteristics of litter and the changes in soil organic carbon and organic carbon in soil aggregates under the different moisture conditions were analyzed.It was found that,compared with W1,the soil microbial biomass carbon in the SL and SR treatments in the W2 treatment increased(P<0.05)by 25.2％and 40.7％,respectively.The W2 treatment not only significantly accelerated the litter decomposition rate but also significantly increased the SOC content(P<0.05).In addition,adequate moisture conditions facilitate the formation of mineral-associated organic carbon in soils of semi-arid regions.Specifically,in the W2 treatment,the new carbon formation efficiency of the SL and SR treatments increased significantly by 6.5％and 8.0％respectively compared with W1(P<0.05).These findings indicate that in the temperate grasslands of semi-arid regions,an increase in soil moisture can not only promote litter decomposition,but also promote a greater allocation of litter carbon to soil aggregates<0.053 mm,thereby facilitating the formation of mineral-associated organic carbon.