Local temperature increases reduce soil microbial residues and carbon stocks

Warming is known to reduce soil carbon (C) stocks by promoting microbial respiration, which is associated with the decomposition of microbial residue C (MRC). However, the relative contribution of MRC to soil organic C (SOC) across temperature gradients is poorly understood. Here, we investigated the contribution of MRC to SOC along two independent elevation gradients of our model system (i.e., the Tibetan Plateau and Shennongjia Mountain in China). Our results showed that local temperature increases were negatively correlated with MRC and SOC. Further analyses revealed that rising temperature reduced SOC via decreasing MRC, which helps to explain future reductions in SOC under climate warming. Our findings demonstrate that climate warming has the potential to reduce C sequestration by increasing the decomposition of MRC, exacerbating the positive feedback between rising temperature and CO2 efflux. Our study also considered the influence of multiple environmental factors such as soil pH...

众所周知，气候变暖可通过促进微生物呼吸作用降低土壤碳（C）库，而该过程与微生物残体碳（MRC）的分解紧密关联。然而，当前学界对沿温度梯度分布的微生物残体碳对土壤有机碳（SOC）的相对贡献仍缺乏深入认知。本研究依托我国青藏高原与神农架山地两处独立的海拔梯度样带作为模式系统，探究了微生物残体碳对土壤有机碳的贡献。研究结果表明，局地升温与微生物残体碳、土壤有机碳均呈显著负相关。进一步分析显示，升温可通过降低微生物残体碳含量减少土壤有机碳储量，这一发现有助于阐释气候变暖背景下未来土壤有机碳的衰减趋势。本研究结果证实，气候变暖或可通过加速微生物残体碳的分解削弱土壤碳固存能力，加剧升温与二氧化碳（CO₂）排放通量之间的正反馈效应。此外，本研究还考量了土壤pH值等多种环境因子的影响……