Year-long carbon dioxide exchange above a broadleaf deciduous forest in Sapporo, Northern Japan

This paper reports the results of a full year (2000) of measurements of CO₂ flux at a successional forest of mature birch and growing oak with Sasa-bamboo in Sapporo, Japan. Eddy covariance fluxes of CO₂ were obtained using a closed-path infrared gas analyzer. Changes in CO₂ storage under the eddy-flux measurement level were quantified using vertical profiles of the CO₂ concentration. Seasonal variations in net CO₂ exchange between the forest and the atmosphere are discussed in terms of both phenological developments of the forest canopy and micrometeorological variables. To estimate the annual exchange of CO₂, the net CO₂ exchange data both during periods of poor turbulence and during periods of missing data were replaced by simple parametric models based on measurements of soil temperatures and photosynthetically active radiation. The corrected annual carbon sequestration estimate was 260 g C m⁻². The estimates of annual gross carbon gain and loss at the forest were 1120 and 860 g C m⁻².