Influence of snowpack on soil organic carbon decomposition in a northern peatland

Peatlands play a significant role in maintaining the carbon balance and regulating the climate. The turnover of soil organic carbon (SOC) in peatlands is mediated by snowpack, which affects microbial decomposition through its regulation of hydrothermal conditions. However, the impact of snowpack on carbon dynamics in peatlands is not fully understood, particularly in the context of decline in snowpack due to climate warming. To address this issue, an on-site experiment was conducted involving snowpack manipulation (undisturbed and snow removal) to investigate the effects of snowpack on SOC decomposition at depths of 0-30 cm (topsoil) and 30-60 cm (subsoil). Various techniques such as X-ray absorption near-edge structure, synchrotron radiation micro computed tomography technology and microbial metagenomics were utilized to measure SOC content and fractions, pore structure and bacterial community's structure and function. Results showed that snow removal delayed the start of soil freezing date by 27 days and advanced the start of thawing date by 39 days, increased maximum freezing depth by 27.9 cm and frequency of freeze-thaw cycles, and decreased average temperature of topsoil and subsoil by 1.48 degrees C and 1.34 degrees C, respectively. Additionally, snow removal increased SOC content by 8.27 % and 3.19 % and its stability by 53 % and 13.92 % in the topsoil and subsoil, respectively, and decreased microbial decomposition potential functioning by 55.89 % and 5.75 % in both soil layers. The three-dimensional spatial distribution of SOC and soil pores at the micro-scale indicated that snow removal significantly influenced pore structure and microbe feedback loops, thereby affecting SOC decomposition. Notably, snow removal led to an increase in the proportion of micropores by 3.44 % and 4.41 % in the topsoil and subsoil, respectively, suggesting enhanced protection of pore structure and preservation of SOC during decomposition processes. Overall, the findings suggest that snow removal may intensify the response of carbon pools to climate change in peatlands.