Soil priming is a microbial-driven process, which determines key soil–climate feedbacks in response to fresh carbon inputs. Despite its importance, the microbial traits behind this process are largely undetermined. Knowledge of the role of these traits is integral to advance our understanding of how soil microbes regulate carbon (C) emissions in forests, which support the largest soil carbon stocks globally. Using metagenomic sequencing and ¹³C-glucose, we provide unprecedented evidence that microbial traits explain a unique portion of the variation in soil priming across forest biomes from tropical to cold temperature regions. We show that microbial functional profiles associated with the degradation of labile C, especially rapid simple sugar metabolism, drive soil priming in different forests. Genes involved in the degradation of lignin and aromatic compounds were negatively associated with priming effects in temperate forests, whereas the highest level of soil priming was associated with β-glucosidase genes in tropical/subtropical forests. Moreover, we reconstructed, for the first time, 42 whole bacterial genomes associated with the soil priming effect and found that these organisms support important gene machinery involved in priming effect. Collectively, our work demonstrates the importance of microbial traits to explain soil priming across forest biomes and suggests that rapid carbon metabolism is responsible for priming effects in forests. This knowledge is important because it advances our understanding on the microbial mechanisms mediating soil–climate feedbacks at a continental scale.

中文翻译：

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微生物特征决定了土壤碳排放，以响应整个生物群落森林中的新鲜碳输入

土壤启动是一个微生物驱动的过程，它决定了响应新鲜碳输入的关键土壤-气候反馈。尽管它很重要，但这一过程背后的微生物特征在很大程度上尚未确定。了解这些特征的作用对于促进我们了解土壤微生物如何调节森林中的碳 (C) 排放至关重要，而森林支持全球最大的土壤碳储量。使用宏基因组测序和¹³C-葡萄糖，我们提供了前所未有的证据，证明微生物特征解释了从热带到寒冷地区的森林生物群落中土壤启动变化的独特部分。我们表明，与不稳定 C 的降解相关的微生物功能特征，尤其是快速的单糖代谢，推动了不同森林中的土壤启动。参与木质素和芳香化合物降解的基因与温带森林中的启动效应呈负相关，而最高水平的土壤启动与热带/亚热带森林中的β-葡萄糖苷酶基因有关。此外，我们首次重建了 42 个与土壤启动效应相关的完整细菌基因组，发现这些生物体支持与启动效应相关的重要基因机制。集体，我们的工作证明了微生物特征对解释森林生物群落中土壤启动的重要性，并表明快速的碳代谢是森林启动效应的原因。这一知识很重要，因为它促进了我们对在大陆尺度上介导土壤-气候反馈的微生物机制的理解。