Effects of Decreased Snow Cover Depth on Leaf Litter Acid-Insoluble Residue Degradation in a Subalpine Forest
[Objective]The acid-insoluble residue(AIR)of leaf litter is an important precursor for the formation of forest soil organic matter.The degradation process of AIR may be influenced by reduced snowfall caused by global climate warming,but the specific mechanism is still unclear.[Method]The study focused on the leaf litter of two deciduous tree species,Betula albosinensis and Larix mastersiana,in a subalpine forest of western Sichuan.By conducting field experiments with control over snow cover(control,50%and 100%reduction in snow cover),the study investigated the impact of reduced snow cover on the degradation of acid-insoluble residue(AIR)during key stages of leaf litter decomposition.[Result]During the two-years'decomposition process,the content of AIR in the leaf litter of B.albosi-nensis and L.mastersiana showed an overall increasing trend,with increases of 50.37%and 39.63%,re-spectively.Compared to the natural snow cover,the reduced snow cover treatments resulted in higher re-sidual levels of AIR in the leaf litter,indicating that reduced snow cover promoted the accumulation of AIR during the decomposition process.However,this promoting effect gradually diminishes after one year of decomposition.The amount of AIR showed an accumulation pattern during the entire decomposi-tion process of L.mastersiana litter,while it showed a net loss pattern in B.albosinensis litter(with higher initial nitrogen and phosphorus content but lower lignin content),indicating that there were spe-cies differences in the degradation of AIR among different species.Furthermore,the correlation and re-gression analysis results indicated that the AIR degradation positively correlated with pH,nitrogen,and lignin content,while negatively correlated with mean temperature,phosphorus,cellulose content,and microbial biomass carbon.[Conclusion]In summary,the snow cover reduction promotes the accumula-tion of AIR during the decomposition process,and this process jointly regulated by environmental fac-tors,leaf nutrients,structural carbon content,and microbial biomass.The research results provide scien-tific basis data for a deeper understanding of the material cycle process and soil carbon sink function man-agement in subalpine forest ecosystems.
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