Soil microbial necromass plays a critical role in soil organic C (SOC) sequestration, while the long-term response of microbial necromass to climate change remains largely unclear. Here, we used amino sugars as biomarkers and examined their variation after 8 years of continuous manipulation of elevated CO₂ (eCO₂), warming, and their combined interaction in a paddy soil. Our results showed that eCO₂ increased the concentrations of all amino sugar compounds by 6.5–28.9% while warming had no effect on the accumulation of glucosamine and galactosamine but increased muramic acid concentration by 22.1–29.1%. Elevated CO₂ increased the contribution of microbial necromass C to SOC storage, mainly by increasing fungal-derived C, whereas warming increased the bacterial-derived C proportion in SOC. Furthermore, the combined effect of eCO₂ and warming yielded the highest total microbial necromass and SOC accumulation, although the ratio of fungal to bacterial necromass C in SOC remained unchanged. Structural equation models showed that root biomass had an indirect positive effect on total amino sugar concentration, mainly through increased microbial biomass, whereas N-acetylglucosaminidase activity had a direct negative effect on total amino sugar accumulation. These differential responses of microbial necromass to climate change may further alter the sequestration of SOC. This study is only based on one sampling time, and future research should involve more sampling times so as to have the temporal dynamics of the studied properties. Our findings emphasize the contribution of the microbial-derived C to soil C stock under long-term elevated CO₂ and warming in a rice-wheat rotation system, which reveals an important mechanism of microbial-mediated C sequestration under climate change.

土壤微生物坏死菌在土壤有机碳（SOC）的固存中起关键作用，而微生物坏死菌对气候变化的长期反应在很大程度上尚不清楚。在这里，我们使用氨基糖作为生物标志物，并在连续处理升高的CO ₂（eCO ₂），变暖及其在稻田土壤中的相互作用后的8年中检查了它们的变化。我们的结果表明，eCO ₂将所有氨基糖类化合物的浓度提高了6.5–28.9％，而升温对葡萄糖胺和半乳糖胺的积累没有影响，但将山梨酸浓度提高了22.1–29.1％。升高的CO ₂主要通过增加真菌衍生的C增加微生物坏死微生物C对SOC储存的贡献，而升温则增加了细菌衍生的C在SOC中的比例。此外，eCO ₂的综合作用尽管SOC中真菌与细菌坏死C的比例保持不变，但变暖产生的微生物总坏死和SOC最高。结构方程模型表明，根生物量对总氨基糖浓度有间接的正影响，主要是通过增加微生物的生物量，而N-乙酰氨基葡萄糖苷酶活性对总氨基糖的积累有直接的负影响。微生物坏死对气候变化的这些不同反应可能会进一步改变SOC的固存。这项研究仅基于一个采样时间，未来的研究应涉及更多的采样时间，以便具有所研究属性的时间动态。我们的研究结果强调了在长期CO ₂长期升高的情况下微生物衍生的C对土壤C储量的贡献 稻麦轮作系统的变暖和变暖，揭示了气候变化下微生物介导的碳固存的重要机制。