Forests,characterized by diverse types,complex structures,and high sensitivity to environmental changes,account for approximately 45% of the carbon stock in global forest ecosystems and 52% of the global soil carbon pool in the 0-100 cm layer. However,the carbon sequestration potential and key mechanistic processes of forest soils remain limited. Consequently,substantial uncertainties persist in estimating forest soil carbon storage and net carbon sink. In this study,we compiled definitions of terms related to forest soil organic carbon (SOC),including stock,density,concentration,accrual,sequestration,and carbon sink; reviewed the mechanisms of SOC stability,including chemical structure stability,physical protection by aggregates,adsorption by metal oxides and clay minerals,and the dominant role of biological and environmental factors in shaping SOC stabilization. Recent studies suggested that the diversity of SOC components and the complexity of their functions in forests played a critical role in maintaining carbon stability. We conducted a comparative analysis of the main principles,advantages,and limitations of various methods for measuring forest SOC stocks and accrual; and literature review to estimate that the global patter of SOC stocks in the 0-100 cm layer in forest soils,ranging from 383 to 787 Pg C (Pg=10¹⁵g). Current studies showed significant discrepancies in the annual variation of global forest SOC stocks,ranging from a decrease of 349 Tg C (Tg=10¹²g) to an increase of 498 Tg C per year in the 0-100 cm layer. In China,the estimated range of SOC stocks in the 0-100 cm layer in forests ranged from 16.0 to 34.2 Pg C,and the estimated annual variation in SOC stocks in forests ranged from a decrease of 61.5 Tg C to an increase of 217.3 Tg C in the 0-100 cm layer. The above-estimated results remain a great uncertainty in forest SOC stocks and accrual. Recent studies suggested that global forest carbon capacity and sequestration potential were substantial. However,varying perspectives exist regarding whether there was an upper limit to SOC. The impacts of climate change on forest SOC stocks and long-term sequestration potential also remain uncertain. Future studies need to focus on the connections between forest community structure and soil carbon sequestration processes by using interdisciplinary approaches,aiming to understand the mechanisms underlying forest soil carbon stability from a new perspective of the diversity of carbon components and the complexity of their functions. A national-scale long-term SOC monitoring network by incorporating soil C monitoring into the national forest resource inventory system and a major scientific program for enhancing C sequestration in forest soils should be initiated. Also,it is necessary to develop a technical system of forest management to enhance soil sequestration and maintain soil C stability,including natural forest protection,restoration,and management strategies and plantations silviculture regime,including cultivating high-carbon tree species,optimizing stand structure,implementing reasonable harvesting practices,and extending rotation periods.