スギ人工林と落葉広葉樹林での林床面メタン吸収速度の観測

Rate of methane uptake on forest floor, ground temperature and soil moisture were measured in two plantations of Sugi and in a deciduous broad-leaved forest. The average rate of methane uptake in the two Sugi forests and broad-leaved forest was 1.93mgCH_4/m^2/d, 2.32mgCH_4/m^2/d and 2.75mgCH_4/m^2/d, respectively. The seasonal variations of the rate of methane uptake were affected strongly by the seasonal variation of the soil moisture condition in two Sugi forests. In the broad-leaved forest both the soil moisture condition and the ground temperature affected the seasonal variation. Experiments of soil moisture control using soil samples in the observation sites indicated that the rate of methane absorbed by the soil surface was inversely proportional to the soil moisture contents. The rates of methane uptake were estimated using a model equation with the observed soil moisture condition and ground temperature. The prediction had good results. According to the model simulations, the order of magnitude of the methane uptake in the sites was affected by the response of the methane uptake to the ground temperature and the soil moisture and by the variations of the soil moisture condition in the sites.