Permafrost thaw in northern ecosystems may cause large quantities of carbon (C) to move from soil to atmospheric pools. Because soil microbial communities play a critical role in regulating C fluxes from soils, we examined microbial activity and greenhouse gas production soon after permafrost thaw and ground collapse (into collapse‐scar bogs), relative to the permafrost plateau or older thaw features. Using multiple field and laboratory‐based assays at a field site in interior Alaska, we show that the youngest collapse‐scar bog had the highest CH₄ production potential from soil incubations, and, based upon temporal changes in porewater concentrations and ¹³C‐CH₄ and ¹³C‐CO₂, had greater summer in situ rates of respiration, methanogenesis, and surface CH₄ oxidation. These patterns could be explained by greater C and N availability in the young bog, while alternative terminal electron accepting processes did not play a significant role. Field diffusive CH₄ fluxes from the young bog were 4.1 times greater in the shoulder season and 1.7–7.2 times greater in winter relative to older bogs, but not during summer. Greater relative CH₄ flux rates in the shoulder season and winter could be due to reduced CH₄ oxidation relative to summer, magnifying the importance of differences in production. Both the permafrost plateau and collapse‐scar bogs were sources of C to the atmosphere due in large part to winter C fluxes. In collapse scar bogs, winter is a critical period when differences in thermokarst age translates to differences in surface fluxes.

中文翻译：

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经历多年冻土融化的北方泥炭地的碳通量和微生物活动

北部生态系统中的多年冻土融化可能导致大量碳（C）从土壤转移到大气池。由于土壤微生物群落在调节土壤中C的通量中起关键作用，因此，我们检查了相对于多年冻土高原或较旧融化特征的多年冻土和地面塌陷（塌陷成沼泽）之后的微生物活动和温室气体产生。通过在阿拉斯加内部的一个现场进行的多场和基于实验室的分析，我们表明，最年轻的塌陷沼泽在土壤培养中具有最大的CH ₄产生潜力，并且基于孔隙水浓度和¹³ C-CH的时间变化₄和¹³ C‐CO ₂，具有较高的夏季原位呼吸，甲烷生成和表面CH ₄氧化率。这些模式可以通过年轻沼泽中较高的C和N利用率来解释，而替代性的末端电子接受过程并未发挥重要作用。相对于年长的沼泽，年轻沼泽的田间扩散CH ₄通量在肩部季节要大4.1倍，在冬天要大1.7-7.2倍，但在夏天没有。肩膀季节和冬季CH ₄相对通量增加可能是由于CH ₄减少相对于夏季氧化，放大了生产差异的重要性。多年冻土高原和坍塌的沼泽都是大气中碳的来源，这在很大程度上是由于冬季的碳通量。在坍塌的疤痕沼泽中，冬季是一个关键时期，此时热喀斯特年龄的差异转化为表面通量的差异。