菌根真菌作为植物与土壤之间养分和碳流动的重要通道,能够通过调控植物碳输入、根际微生物过程、土壤团聚体形成及有机碳分解与稳定等过程深刻影响土壤有机碳动态,系统梳理其作用机制对于深化陆地生态系统碳循环认识、提升土壤碳汇管理与气候变化应对能力具有重要意义。笔者基于近年来菌根真菌与土壤有机碳关系的主要研究成果,系统梳理菌根真菌调控土壤有机碳输入、分解、转化与稳定的研究进展,提出菌根真菌通过植物-菌根互作、酶活性调控、矿物保护3条核心途径影响土壤有机碳动态的研究框架。菌根真菌对土壤有机碳的净效应取决于这3条途径的作用方向及相对强弱,但现有研究在定量区分各途径相对贡献方面仍显不足。未来应重点结合稳定同位素示踪、分子标记和模型模拟等,定量解析菌根真菌生物量周转、残体形成、微生物碳利用效率及矿物结合态有机碳形成过程,并将菌根过程纳入生态系统碳循环模型,从而提升对土壤碳汇形成机制及其全球变化响应的预测能力。

As a critical pathway mediating nutrient and carbon fluxes between plants and soil, mycorrhizal fungi can profoundly regulate soil organic carbon (SOC) dynamics by modulating plant carbon inputs, rhizosphere microbial processes, soil aggregate formation, and the decomposition and stabilization of organic carbon. A systematic synthesis of these regulatory mechanisms is therefore of great significance for deepening the understanding of terrestrial ecosystem carbon cycling, and for optimizing soil carbon sink management and climate change mitigation strategies. Based on recent advances in research on the relationships between mycorrhizal fungi and SOC, this review systematically summarized the roles of mycorrhizal fungi in regulating the input, decomposition, transformation, and stabilization of SOC, and proposed a conceptual framework in which mycorrhizal fungi affect SOC dynamics through three core pathways: plant-mycorrhizal interactions, enzymatic activity regulation, and mineral protection. The net effect of mycorrhizal fungi on SOC stocks depends on the functional direction and relative strength of these three pathways; however, their relative contributions remain difficult to disentangle quantitatively in current studies. Future investigations should integrate stable isotope tracing, molecular biomarkers, and model simulation approaches to quantitatively elucidate the processes of mycorrhizal fungal biomass turnover, necromass formation, microbial carbon use efficiency, and the formation of mineral-associated organic carbon, and should further incorporate mycorrhizal processes into ecosystem carbon cycle models. These efforts will improve the predictive capacity for the mechanisms underlying soil carbon sink formation and their responses to global environmental change.