Soil organic carbon is a key determinant of CH₄ sink in global forest soils

Soil organic carbon (SOC) is a primary regulator of the forest-climate feedback. However, its indicative capability for the soil CH₄ sink is poorly understood due to the incomplete knowledge of the underlying mechanisms. Therefore, SOC is not explicitly included in the current model estimation of the global forest CH₄ sink. Here, using in-situ observations, global meta-analysis, and process-based modeling, we provide evidence that SOC constitutes an important variable that governs the forest CH₄ sink. We find that a CH₄ sink is enhanced with increasing SOC content on regional and global scales. The revised model with SOC function better reproduces the field observation and estimates a 39% larger global forest CH₄ sink (24.27 Tg CH₄ yr^-1) than the model without considering SOC effects (17.46 Tg CH₄ yr^-1). This study highlights the role of SOC in the forest CH₄ sink, which shall be factored into future global CH₄ budget quantification.