CO₂, Water Vapor and Energy Fluxes in a Larch Forest in Northeast China

Abstract

　A flux observation site was built in northeast China to identify the energy, H₂O and CO₂ fluxes of a larch forest ecosystem and the effect of environmental variables. The energy balance was estimated to be 86% using half-hourly flux data, but the energy was completely closed when the accumulated data was used. This indicated the possibility of energy storage in the forest at this site. Radiation plays an important role in controlling the ecosystem carbon sequestration. The ecosystem sequestered 6.18 μmol m^-2 s^-1 on clear days, much higher than the 3.62 μmol m^-2 s^-1 on cloudy days. However, the light use efficiency of the ecosystem was much higher on cloudy days than on clear days, the reason being generally ascribed to the more diffuse radiation on cloudy days. However, the lower vapor pressure deficit on cloudy days than on clear days also contributed to this result.