Linking annual tree growth with eddy-flux measures of net ecosystem productivity across twenty years of observation in a mixed conifer forest

•The relationship between NEP and tree biomass increment was assessed.•We summarized NEP from previous-year fall to current-year fall.•Tree biomass increment lagged one year behind NEP for half of the time-series.•In recent years tree biomass increment became synchronized with current-year NEP.•A shift to synchrony may reflect changes in stand-level carbon allocation dynamics.