The response of soil labile organic carbon in cold temperate forest to snowpack removal is both sensitive and resilient

Global snowpack pattern is changing by climate change, especially in high-latitude and high-altitude areas, which increased the risk of soil carbon (C) pool instability because of a noticeable decrease in snowpack thickness as the climate warming. In this study, we conducted a two-year snowpack removal experiment including snowpack removal during the whole snow-covered period and snowpack removal during the frozen period followed by the return of snowpack before the freeze-thaw period. The responses and driving relationships of soil C pool components (mineral-associated organic C, MOC and particulate organic C, POC), aggregate distribution, and biomass of microbe and fine roots to snowpack removal were studied in the freeze-thaw period (FTP) and at the end of growing season (EGS). The results showed that snowpack removal did not cause a significant change in soil MOC, but increased POC by 61.9 % in the FTP. And the return of snowpack failed to cause a significant effect on C components. The snowpack removal led to reductions in the mean weight diameter of soil aggregates, total phospholipid fatty acid, the hydrolase and oxidoreductase activity, and the ratio of biomass between live and dead fine roots in the FTP. At EGS, all above factors had been restored. These variables during the FTP exhibited a cascade response to snowpack removal, as well as the recovery process during the growing season. Soil aggregate and microbial biomass were the main drivers for POC. Our study indicated that soil labile C components in cold temperate forests were both sensitive and capable of self-regulation in response to continuous two-year snowpack removal.