Résumé
We show that ecosystem‐specific aboveground net primary productivity (SANPP, g g−1 day−1, productivity on a per gram basis) can be predicted from species‐level measures of potential relative growth rate (RGRmax), but only if RGRmax is weighted according to the species’ relative abundance. This is in agreement with Grime's mass‐ratio hypothesis. Productivity was measured in 12 sites in a French Mediterranean post‐agricultural succession, while RGRmax was measured on 26 of the most abundant species from this successional sere, grown hydroponically. RGRmax was only weakly correlated (r2 = 0.12, P < 0.05) with field age when species abundance was not considered, but the two variables were strongly correlated (r2 = 0.81, P < 0.001) when the relative abundance of species in each field was taken into account. SANPP also decreased significantly with field age. This resulted in a tight relationship (r2 = 0.77, P < 0.001) between productivity and RGRmax weighted according to species relative biomass contribution. Our study shows that scaling‐up from the potential properties of individual species is possible, and that information on potential and realized species traits can be integrated to predict ecosystem functioning.