Factors Affecting CO2, CH4, and N2O Fluxes in Temperate Forest Soils

Greenhouse gas (GHG) fluxes from forests, including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), are regulated by complex interactions of abiotic and biotic factors. A better understanding of these interactions involving GHGs can help manage forests and enhance their sequestration potential. This review examines how soil properties (moisture, temperature, and pH) and tree species-specific traits (litter quality, carbon storage, and microbial regulation) interactively control GHG dynamics in temperate forest soils, moving beyond a single-factor perspective. This literature review confirms that temperate forest soils are CH4 sinks and sources of CO2 and N2O; however, flux direction and magnitude differ across spatial and temporal scales. CH4 fluxes show high spatial variability and are sensitive to biogeochemical conditions. While soil temperature and moisture are well studied, their combined effects with site-specific variables such as substrate availability, soil texture, and canopy structure remain underexplored. Tree litter plays a dual role: chemically influencing microbial physiological/functional traits through priming, thereby affecting CO2 and N2O, and physically limiting CH4 diffusion. These mechanisms collectively determine whether soils act as GHG sources or sinks, and future research should account for how litter priming may override their carbon sink function while integrating site-specific factors to improve GHG predictions and forest management.