Permafrost (PF)-affected soils are widespread in the Arctic and store about half the global soil organic carbon. This large carbon pool becomes vulnerable to microbial decomposition through PF warming and deepening of the seasonal thaw layer (active layer [AL]). Here we combined greenhouse gas (GHG) production rate measurements with a metagenome-based assessment of the microbial taxonomic and metabolic potential before and after 5 years of incubation under anoxic conditions at a constant temperature of 4°C in the AL, PF transition layer, and intact PF. Warming led to a rapid initial release of CO₂ and, to a lesser extent, CH₄ in all layers. After the initial pulse, especially in CO₂ production, GHG production rates declined and conditions became more methanogenic. Functional gene-based analyses indicated a decrease in carbon- and nitrogen-cycling genes and a community shift to the degradation of less-labile organic matter. This study reveals low but continuous GHG production in long-term warming scenarios, which coincides with a decrease in the relative abundance of major metabolic pathway genes and an increase in carbohydrate-active enzyme classes.

中文翻译：

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长期缺氧变暖情景对永久冻土影响土壤微生物群落结构和功能潜力的影响

受永久冻土 (PF) 影响的土壤在北极广泛分布，储存了全球大约一半的土壤有机碳。由于 PF 变暖和季节性解冻层（活性层 [AL]）的加深，这个大型碳库变得容易受到微生物分解。在这里，我们将温室气体 (GHG) 生产率测量与基于宏基因组的微生物分类学和代谢潜力评估相结合，在 AL、PF 过渡层中，在 4°C 恒温缺氧条件下培养 5 年之前和之后，和完整的PF。变暖导致 CO ₂的快速初始释放，并在较小程度上导致所有层中的CH ₄释放。在初始脉冲之后，尤其是在 CO _{2 中}生产，温室气体生产率下降，条件变得更加产甲烷。基于功能基因的分析表明碳和氮循环基因的减少以及群落向不稳定有机物降解的转变。这项研究揭示了长期变暖情景中温室气体产量低但持续的情况，这与主要代谢途径基因的相对丰度下降和碳水化合物活性酶类别的增加相吻合。