Seasonal and interannual variations in carbon dioxide exchange of a temperate larch forest

This paper reports 3-year measurements (2001–2003) of the net ecosystem CO2 exchange (NEE) over a northern Japan larch plantation forest, using an eddy covariance technique with both open- and closed-path systems. The study evaluates interannual variations in the seasonal patterns of NEE, the annual NEE, clarifying the factors controlling the carbon balance. NEE for both open- and closed-path systems look equivalent from the half-hourly mean values; however, there is a small systematic bias in the annual cumulative totals. In this study, we used closed-path data because open-path data during winter are doubtful and the annual NEE from closed-path data was closer to the biometric NEP than that from open-path data.