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To clarify the reason for the higher CH 4 uptake rate in Japanese forest soils, twenty-seven sites were established for CH 4 flux measurement. The first order rate constant for CH 4 uptake was also determined using soil core incubation at 14 sites. The CH 4 uptake rate had a seasonal fluctuation, high in summer and low in winter, and the rate correlated with soil temperature at 17 sites. The annual CH 4 uptake rates ranged from 2.7 to 24.8 kg CH 4 ha -1 y -1 (the average of these rates was 9.7 or 10.9 kg CH 4 ha -1 y -1 , depending on method of calculation), which is somewhat higher than the uptake rates reported in previous literature. The averaged CH 4 uptake rate correlated closely with the CH 4 oxidation rate of the topsoil (0-5 cm) in the study sites. The CH 4 oxidation constant of the topsoil was explained by a multiple regression model using total pore volume of the soil, nitrate content, and C/N ratio (p \ 0.05, R 2 = 0.684). This result and comparison with literature data suggest that the high CH 4 uptake rate in Japanese forest soils depends on the high porosity probably due to volcanic ash parent materials. According to our review of the literature, the CH 4 uptake rate in temperate forests in Europe is significantly different from that in Asia and North America. A new global CH 4 uptake rate in temperate forests was estimated to be 5.4 Tg y -1 (1 SE is 1.1 Tg y -1 ) on a continental basis.

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