Freeze-thaw (FT) events exert a great physiological stress on soil microorganisms and hence impact biogeochemical processes in soils. As numerous environmental factors affect microbial and chemical responses to FT, a better understanding of the leverage factors that regulate the responses to FT events is required. To date, FT-induced shifts and transformations in microbial and resource stoichiometry have received particularly little attention. We exposed fifteen Luvisol soils with different time after restoration and corresponding differences in soil organic C contents from a postmining agricultural chronosequence to a single FT event and analysed changes in soil chemistry and microbial stoichiometry one hour and eighteen hours after thawing. FT considerably altered soil biochemical attributes within the first hours of thawing. Microbial biomass C declined substantially after FT, and its relative losses were positively correlated with enhanced dissolved organic C contents. Thus, microbial cell lysis likely led to the significant increase of dissolved organic C. Moreover, microbial biomass C losses were disproportionally higher in C-rich soils, suggesting that soil microorganisms in high-C soils might be particularly prone to FT stress. Microbial biomass N marginally decreased one hour after thawing, yet returned to initial levels eighteen hours after thawing. The alternating responses of microbial biomass C and N caused a strong stoichiometric reduction of the microbial C:N ratio. The resulting microbial oversaturation with N relative to C is likely the first step in the chain of processes that generally lead to the high N losses commonly recorded in agricultural soils in the aftermath of FT events. Metabolic activity of the soil microbial community increased with the relative decline of the microbial biomass C:N ratio eighteen hours after thawing, suggesting increased levels of microbial metabolic expenditure due to stoichiometric shifts. The strength of the FT-driven biochemical responses was strongly dependent on soil organic C content, indicating that high-C soils might be especially vulnerable to initial C and N losses due to shifts in microbial stoichiometry.

冻融 (FT) 事件对土壤微生物产生巨大的生理压力，从而影响土壤中的生物地球化学过程。由于许多环境因素会影响微生物和化学对 FT 的反应，因此需要更好地了解调节对 FT 事件反应的杠杆因素。迄今为止，由 FT 引起的微生物和资源化学计量的转变和转变很少受到关注。我们在恢复后的不同时间暴露了 15 种 Luvisol 土壤，以及土壤有机碳含量从采矿后农业时间序列到单个 FT 事件的相应差异，并分析了解冻后 1 小时和 18 小时土壤化学和微生物化学计量的变化。FT 在解冻的最初几个小时内显着改变了土壤生化特性。FT后微生物生物量C显着下降，其相对损失与溶解有机C含量增加呈正相关。因此，微生物细胞裂解可能导致溶解有机碳的显着增加。此外，富含碳的土壤中微生物生物量碳的损失不成比例地更高，这表明高碳土壤中的土壤微生物可能特别容易受到 FT 胁迫。解冻 1 小时后微生物生物量 N 略有下降，但在解冻 18 小时后恢复到初始水平。微生物生物量 C 和 N 的交替响应导致微生物 C:N 比的化学计量降低。由此产生的微生物相对于 C 的 N 过饱和可能是过程链中的第一步，该过程通常导致 FT 事件后农业土壤中通常记录的高 N 损失。土壤微生物群落的代谢活性随着微生物生物量 C:N 比在解冻 18 小时后的相对下降而增加，表明由于化学计量变化导致微生物代谢消耗水平增加。FT 驱动的生化反应的强度在很大程度上取决于土壤有机碳含量，表明由于微生物化学计量的变化，高碳土壤可能特别容易受到初始 C 和 N 损失的影响。解冻后 18 小时的 N 比，表明由于化学计量变化导致微生物代谢消耗水平增加。FT 驱动的生化反应的强度在很大程度上取决于土壤有机碳含量，表明由于微生物化学计量的变化，高碳土壤可能特别容易受到初始 C 和 N 损失的影响。解冻后 18 小时的 N 比，表明由于化学计量变化导致微生物代谢消耗水平增加。FT 驱动的生化反应的强度在很大程度上取决于土壤有机碳含量，表明由于微生物化学计量的变化，高碳土壤可能特别容易受到初始 C 和 N 损失的影响。