| Flux of soil CH4 was measured by closed static chamber-gas chromatograph technique in larix gmelinii forest of Great Hingan mountains during the peak of growing season, then, the flux of soil CH4 was measured during the freezing-thawing period in cold temperate zone.The results showed that the soil of this region was a sink of CH4 to the atmosphere as a whole during the peak of growing season,the daily mean soil CH4 flux(mean±SE) was -0.05±0.01 mg·m-2·h-1 during the observation period and the peak values appeared at about 0:00 and 16:00 respectively. Removal of surface litter had no significant effect on CH4 flux during the observation period,but there are some differences in the scale and time distribution.the Iitter-free plot has larger scale than the plot with Iitters. CH4 flux was obviously correlated with soil temperature,but the liner correlation coefficient is relatively small.However,CH4 flux was not correlated with soil moisture,which indicated that soil temperature was a main factor to control the CH4 flux during the peak of growing season in this region.The diurnal variation of CH4 flux showed different characteristics in larix gmelinii forest of Great Hingan mountains during the freezing-thawing period. It was a absorption of CH4 flux as a whole. the diurnal variation of CH4 flux showed double peak curves, the time of the peak occurring was different and exhibited irregular curves.Removal of surface litter had different effect on CH4 flux during the freezing-thawing period. There was significant effect on CH4 flux.CH4 flux of the Iitter-free plot was larger than the plot with Iitters.
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