Soil carbon fluxes are an important component of the carbon cycle in forest ecosystems. Roots play a key role in soil carbon fluxes. The study of root effects on soil carbon fluxes is important for studying greenhouse gases in the cold-temperate tundra. We selected Ledum palustre- Larix gmelinii (DXL), Rhododendron dauricum- Larix gmelinii (DJL), and Sphagnum-Bryum-Ledum palustre- Larix gmelinii (TXL) forests as research object. Further, the roots were broken off by the trench method. Finally, the soils carbon fluxes were measured and analyzed using the portable soil respirometer G4301 for daily and monthly dynamics. Results show that soil CH₄ uptake of DXL and DJL was inhibited by root-break treatments from June to November, with decrease by 15.16%-54.31% and 11.26%-33.84%, respectively. It contributed to the soil CH₄ emission of the TXL, with increase by 19.22%-75.52%. It suppressed soil CO₂ emissions from 3 types of Larix gmelinii forests by 32.29%-87.62%. The effect of root breakage on soil CH₄ in DXL and TXL was the most significant in August with increases of -54.31% and 75.52%, respectively. In DJL, the impact was the most significant in November, with a drop of 33.84%. The effect of root breakage on soil CO₂ emission of the 3 types of Larix gmelinii forests reached the significant degree from June to November. Among them, it was the most significant in November, with the reduction ranging from 54.94%-to 87.62%. Differences in the effects of root breakage on the daily dynamics of soil CH₄ fluxes in the 3 types of Larix gmelinii forests were not significant. However, the effect on soil CO₂ flux was significant. The most significant effects were observed from 14:00--18:00, with decreases ranging from 31.87%-to 62.26%. Soil and air temperatures were main factors that roots influenced changes in soil carbon fluxes. Treatment of root breaks enhanced the effect of soil temperature on daily and monthly changes in soil carbon fluxes. It also attenuated the effect of air temperature on the daily dynamics. It suggests that soil carbon fluxes from root autotrophy may be more active in daily dynamics and more stable in monthly dynamics.