The divergence of micrometeorology sensitivity leads to changes in GPP/SIF between cork oak and poplar

•Nonlinear correlation transformed into linear correlation with aggregation.•GPP of cork oak has intense radiation “depression” while SIF has “promotion”.•The GPP and GPP/SIF of poplar is higher than cork oak and which is opposite in SIF.•GPP/SIF decreases with increasing PAR.•GPP is more sensitive to instantaneous stress, and cork oak is more vulnerable.