Abstract: Soil-microbial biomass stoichiometric characteristics serve as a robust indicator of ecosystem nutrient cycling efficiency， yet the mechanisms by which different artificial grassland restoration modes influence these traits remain unclear. This study investigated 3-year-old artificial grasslands dominated by tall-grass species （SF）， short-grass species （XF）， and a mixed planting of tall- and short-grass species （SFXF） in the Three-River-Source Region， with severely degraded alpine grassland （CK） as the control. Soil organic carbon （SOC）， total nitrogen （TN）， total phosphorus （TP）， microbial biomass carbon （MBC）， nitrogen （MBN）， and phosphorus （MBP） in the 0-10 cm layer were measured to analyze their stoichiometric ratios and microbial quotients. The impacts of different restoration modes on soil-microbial stoichiometric balance were further elucidated.The results demonstrated that all three artificial grassland establishment modes significantly enhanced SOC， MBN， and MBP contents. Specifically， the SF treatment increased soil TN， whereas the XF treatment reduced TN and decreased TP by 50.42%. MBN incresed by 24.36% and 35.59% under SF and XF treatments， respectively. The SFXF treatment decreased the microbial C-quotient by 78.40%， while the XF treatment elevated the microbial N-quotient by 49.61%， and the SFXF treatment reduced it by 11.33%. After restoration， the stoichiometric imbalances in soil-microbial biomass （Cimb：Nimb， Cimb：Pimb， and Nimb：Pimb） increased across all treatments， with the most pronounced escalation observed in the SFXF treatment. Redundancy analysis （RDA） revealed that soil N：P and C：P ratios were key drivers of microbial quotient variations. In conclusion， the SFXF mixed planting exerted the most substantial influence on soil-microbial C-N-P cycling. For practical management， supplemental nitrogen fertilization is recommended to optimize plant growth and improve soil quality.

Key words: Artificial grassland, Microbial biomass, Stoichiometric ratio, Microbial quotient, Stoichiometric imbalance

摘要： 土壤-微生物生物量化学计量特征可有效表征生态系统养分循环效率，但不同人工草地恢复模式对其影响机制尚不明确。本研究以三江源区建植3年的上繁草（SF）、下繁草（XF）及上繁草+下繁草（SFXF）人工草地为研究对象，并以重度退化高寒草地（CK）为对照，采集0~10 cm土层样品，测定土壤有机碳、全氮、全磷及微生物量碳、氮、磷含量，分析其化学计量比与微生物熵的变化。研究结果表明，三种人工草地建植模式均提高了土壤有机碳、微生物量氮和磷含量。SF处理增加了土壤全氮含量，而XF处理则降低了全氮含量，并使全磷含量减少了50.42%。微生物量氮在SF和XF处理分别增加了24.36%和35.59%。SFXF处理使微生物熵碳降低了78.40%，而XF处理提高了微生物熵氮49.61%，SFXF处理则降低了微生物熵氮11.33%。三种人工草地建植后，土壤微生物化学计量不平衡性（Cimb：Nimb、Cimb：Pimb和Nimb：Pimb）均上升，其中SFXF处理的增幅最大。冗余分析表明，土壤氮磷比和碳磷比是调控微生物熵变化的关键因子。综上，SFXF混播模式对土壤-微生物系统碳氮磷循环的影响最为显著，在实际管理中建议适当增加氮素供给以优化植物生长并提升土壤质量。

关键词: 人工草地, 微生物生物量, 化学计量比, 微生物熵, 化学计量不平衡性