Climate warming affects soil carbon (C) dynamics, with possible serious consequences for soil C stocks and atmospheric CO2 concentrations. However, the mechanisms underlying changes in soil C storage are not well understood, hampering long-term predictions of climate C-feedbacks. The activity of the extracellular enzymes ligninase and cellulase can be used to track changes in the predominant C sources of soil microbes and can thus provide mechanistic insights into soil C loss pathways. Here we show, using meta-analysis, that reductions in soil C stocks with warming are associated with increased ratios of ligninase to cellulase activity. Furthermore, whereas long-term (≥5 years) warming reduced the soil recalcitrant C pool by 14%, short-term warming had no significant effect. Together, these results suggest that warming stimulates microbial utilization of recalcitrant C pools, possibly exacerbating long-term climate-C feedbacks.

中文翻译：

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变暖引起的土壤碳损失：来自碳降解酶的新证据。

气候变暖影响土壤碳 (C) 动态，可能对土壤碳储量和大气二氧化碳浓度产生严重后果。然而，土壤碳储存变化的机制尚不清楚，这阻碍了气候碳反馈的长期预测。细胞外酶木质素酶和纤维素酶的活性可用于追踪土壤微生物主要碳源的变化，从而提供对土壤碳损失途径的机制见解。在这里，我们通过荟萃分析表明，随着变暖，土壤碳储量的减少与木质素酶与纤维素酶活性比率的增加有关。此外，虽然长期（≥5年）变暖使土壤顽固碳库减少了14%，但短期变暖没有显着影响。总之，这些结果表明，变暖刺激了微生物对顽固碳库的利用，可能加剧长期气候碳反馈。