Comparison of tree-ring and eddy-covariance derived annual ecosystem production estimates for jack pine and trembling aspen forests in Saskatchewan, Canada

•Tree-ring based hybrid biometric-modelling was used to reconstruct past annual ecosystem production.•Agreement with annual eddy covariance was good for some fluxes but not others, and several causes were evaluated.•Discrepancy bigger for trembling aspen than jack pine possibly due to assumed carbon use efficiency or sampling methods.•Tree-ring based hybrid biometric-modelling enables thorough evaluation of C flux estimates.