Snow removal promotes microbial-mediated organic carbon stabilization within soil aggregates in a peatland of Northeast China

Global climate change exerts profound effects on snow cover, with consequential impacts on microbial activities and the stability of soil organic carbon (SOC) within aggregates. Northern peatlands are significant carbon reservoirs, playing a critical role in mitigating climate change. However, the effects of snow variations on microbial-mediated SOC stability within aggregates in peatlands remain inadequately understood. Here, an in-situ field experiment manipulating snow conditions (i.e., snow removal and snow cover) was conducted to investigate how snow variations affect soil microbial community and the associated SOC stability within soil aggregates (> 2, 0.25–2, and < 0.25 mm) in a peatland of Northeast China. The results showed that snow removal significantly increased the SOC content and stability within aggregates. Compared to the soils with snow cover, snow removal resulted in decreased soil average temperatures in the topsoil (0–30 cm depth) and subsoil (30–60 cm depth) (by 1.48 and 1.34°C, respectively) and increased freeze-thaw cycles (by 11 cycles), consequently decreasing the stability of aggregates in the topsoil and subsoil (by 23.68% and 6.85%, respectively). Furthermore, more recalcitrant carbon and enhanced SOC stability were present in microaggregates (< 0.25 mm) at two soil depths. Moreover, reductions in bacterial diversity and network stability were observed in response to snow removal. Structural equation modeling analysis demonstrated that snow removal indirectly promoted (P < 0.01) SOC stability by regulating carbon to nitrogen (C:N) ratio within aggregates. Overall, our study suggested that microaggregate protection and an appropriate C:N ratio enhanced carbon sequestration in response to climate change.