We studied
CO₂ fluxes derived from eddy covariance (EC), modelled with a stand
photosynthesis model, and upscaled from continuous measurements with chambers in
a Scots pine stand. The annual photosynthesis (GPP_EC), ecosystem
respiration ( R _e,EC) and net CO₂ exchange
(NEE_EC) derived from EC were correlated with each other. Soil
CO₂ efflux dominated R _e for the whole year, most
clearly in winter. The relative contributions of the aboveground respiration
components were largest in spring and early summer. The respiration components
generally followed the seasonal patterns of temperature although
temperature-normalised respiration was higher in the growing season than in
winter. The respiration components showed parallel decline during drought.
Interannual variability in the annual chamber-based CO₂ budgets was
twice as large as in the EC-based fluxes, the uncertainty in the chamber fluxes
was also larger. Using different environmental drivers for estimating
R _e from NEE_EC affected the annual
R _e,EC and GPP_EC ±4%.