Integrated study on carbon dynamics and water cycle in the atmosphere-forest-stream system of mountainous catchment

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Global warming is recognized as the most important environmental issues, and studies on the CO_2 exchange between forest and the atmosphere are conducted all over the world. However, only a few studies focus on the total carbon dynamics involved in hydrological cycle in a forested catchment although this is a key process for evaluating feedback effects of forest ecosystem on the climate. This study attempts to understand this process in a temperate forested catchment based on micrometeorological, biogeochemical and hydrological observations. The findings summarized as follows. (1) Effects of topographical effects on heat/H_2O/CO_2 fluxes were assessed to get their accurate rates. (2) A multilayer model simulating heat/H_2O/CO_2 movements above and within forest canopy was validated by the observations. (3) Biomass heat storage of the forest was estimated from the detailed measurements. (4) Flow pathways on hillslope were estimated using dissolved organic carbon (DOC), sodium and sulfate as the tracers. (5) The dynamics of DOC along the runoff process were classified and the DOC budget within soil was estimated. (6) The dynamics of nitrogen and sulfur were investigated and the characteristics in Japan estimated from our study were compared with those in North America.