植物凋落物的降解是陆地生态系统中主要的碳输入过程之一，对土壤碳平衡具有重要影响。土壤微生物作为凋落物降解过程中的主要分解者，受到增温和降水改变等气候变化因素的影响，进而影响凋落物降解和土壤碳通量。然而，参与凋落物降解的土壤微生物群落对增温和降水改变及其交互作用的响应仍不明确，群落物种组成和功能特征之间的关系尚不清晰，因此限制了对未来气候情景下土壤碳动态的准确预测。本研究依托某增温和降水改变实验样地，连续三年进行纤维素分解袋实验，模拟气候变化情景下植物凋落物的降解。采用扩增子测序技术和基因芯片（GeoChip）技术揭示分解袋富集的微生物群落对增温和降水改变及其交互作用的响应特征。本研究发现，纤维素分解袋富集的微生物群落主要来源于土壤，但相较于土壤群落具有相对丰度更高的碳降解基因、更高的群落水平rrn拷贝数、更大的基因组序列和更高的基因组GC含量，这些特征指示了更强的碳降解能力、更高的最大生长速率和更低的碳利用效率。增温改变了纤维素分解袋中微生物群落的物种组成，增加了包括纤维素酶基因在内的碳降解基因的相对丰度。降水的变化也改变了分解袋中微生物群落的物种组成，且对细菌的影响比真菌更为显著。降水增加有利于高代谢活性的细菌生长，促进了碳降解基因丰度的增加，提高了微生物群落的碳利用效率。增温和降水改变对总土壤呼吸存在交互影响，随着降水增加，增温对总土壤呼吸的效应由抑制转为促进。增温在降水正常的条件下刺激异养呼吸增加了32.3%、纤维素纸质量损失增加了10.9%，在降水减半和降水加倍处理中其效应则不显著。分析微生物与环境因子的关联，发现微生物群落的功能呈现出与物种组成解耦的特征，且受到确定性过程的影响更大，与环境因子的关联性也更强。因此，将碳降解基因作为表征微生物的指标以构建结构方程模型，发现土壤呼吸受到植物和微生物的共同作用，随着水分的增加，微生物群落的变化对土壤呼吸越来越重要，且营养限制成为比土壤温度更重要的影响因素。因此，在降水增加的未来气候变化情景下，需要更加关注土壤微生物的响应。

Plant litter is the primary source of carbon input to soil in terrestrial ecosystems, significantly implicating soil carbon balance. Soil microorganisms, acting as key decomposers in plant litter decomposition, are influenced by climate change factors such as warming and altered precipitation, consequently affecting litter decomposition and soil carbon fluxes. However, the response of soil microbial communities involved in litter decomposition to warming, altered precipitation, and their interactions remains unclear. Additionally, little is understood about the relationship between community taxonomic composition and functional traits, which hinders accurate prediction of soil carbon dynamics under future climate scenarios. Here, a three-year litterbag experiment was conducted in a tallgrass prairie to investigate the response of microbial communities in litterbags to warming, altered precipitation, and their interactions.Our findings revealed that most cellulose-associated microorganisms in litterbags were also detected in bulk soil but exhibited elevated relative abundances of carbon-degrading genes, higher community-level rrn copy numbers, larger genome sizes, and higher genome GC content compared to those in bulk soil, implying enhanced carbon degradation capability, higher maximum growth rates, and lower carbon use efficiency. Warming altered the microbial community composition and increased the relative abundance of carbon-degrading genes in litterbags. Similarly, altered precipitation changed the microbial community composition in litterbags, with a more pronounced impact on bacteria than fungi. Increased precipitation favored bacteria with higher metabolic potential and increased the relative abundance of carbon-degrading genes, consequently enhancing the carbon use efficiency of microbial communities in litterbags. Warming significantly stimulated total soil respiration under decreased and normal precipitation conditions but suppressed it under increased precipitation conditions. Warming significantly increased heterotrophic respiration by 32.3% and increased cellulose decomposition by 10.9% under normal precipitation conditions, with no significant effects observed under altered precipitation conditions. We tried to elucidate this phenomenon from the perspective of the microbial community and found that microbial function appeared to decouple from taxonomic composition. Functional genes of the microbial community in litterbags displayed more deterministic assembly, exhibiting a stronger correlation with environmental factors. By constructing a structural equation model using carbon-degrading genes, we found that microbial community variability assumed increasing importance for soil respiration with rising moisture levels, with soil nutrients emerging as more critical factors than soil temperature for the microbial community. Therefore, under future climate change scenarios with increased precipitation, greater attention should be paid to the response of soil microorganisms.