自動開閉型チャンバを用いた林床面からのCO_2放出速度の長期連続測定

概要

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Soil CO_2 efflux was continuously measured in a deciduous forest for one year using two dynamic closed chambers whose tops were automatically opened after the measurements. Our measurement system decreased differences in environmental conditions between the inside and outside of the chambers. Changes in soil temperature at 0 cm and 2 cm depth were similar inside and outside the two chambers. Changes in soil CO_2 efflux showed two peaks on a non-rainy day in summer, although changes in soil temperature at depths of 0, 2, 5, 10, 25 and 50 cm showed only one peak during the same day. The relationship between the daily mean soil temperature at each depth and soil CO_2 efflux was well represented by an exponential function, while the fluctuations of soil CO_2 efflux were less well explained by soil temperature at 50 cm depth than at 0-25 cm depth. This suggests that the vertical distributions of soil temperature and CO_2 sources, such as soil microbes and plant roots, could affect soil CO_2 efflux. Soil water content also affected soil CO_2 efflux. The decreased soil CO_2 efflux in summer coincided with a decreased soil water content. However, a decrease in soil CO_2 efflux was observed at the onset of rainfall. This suggests the need to consider the effects of soil water content on both the response of CO_2 sources and the diffusion coefficient of CO_2 in the soil.
日本生態学会の論文
2003-04-30