• meta-analysis;
  • elevated CO2;
  • reproduction;
  • reproductive allocation;
  • seed quality;
  • seed nitrogen


  • • 
    Reproductive traits are key characteristics for predicting the response of communities and ecosystems to global change.
  • • 
    We used meta-analysis to integrate data on eight reproductive traits from 159 CO 2 enrichment papers that provided information on 79 species.
  • • 
    Across all species, CO 2 enrichment (500–800 µl l −1 ) resulted in more flowers (+19%), more fruits (+18%), more seeds (+16%), greater individual seed mass (+4%), greater total seed mass (+25%), and lower seed nitrogen concentration, (N) (−14%). Crops and undomesticated (wild) species did not differ in total mass response to elevated CO 2 (+31%), but crops allocated more mass to reproduction and produced more fruits (+28% vs +4%) and seeds (+21% vs +4%) than did wild species when grown at high CO 2 . Seed [N] was not affected by high CO 2 concentrations in legumes, but declined significantly in most nonlegumes.
  • • 
    Our results provide robust estimates of average plant reproductive responses to CO 2 enrichment and demonstrate important differences among individual taxa and among functional groups. In particular, crops were more responsive to elevated CO 2 than were wild species. These differences and the substantial decline in seed [N] in many species have broad implications for the functioning of future natural and agro-ecosystems.