Elevated atmospheric CO2 affects seed production of grassland species

Seed yield and quality of pure stands of five perennial grassland species were tested at elevated atmospheric CO2 (60 Pa) in a three year field experiment. Four species showed a trend to increased seed production, while Plantago lanceolata L. produced a reduced number of seeds. Tests on seed quality revealed that the germination rate was not affected by elevated CO2, the proportion of big seeds, however, was reduced in legume species. It is concluded that at elevated CO2 in a multi-species grassland, the proportion of P. lanceolata seeds in the seed fall of the total community will be reduced, and that the seeds of Trifolium repens L. and Trifolium pratense L. could show a lower vigour at germination. Through these processes elevated CO2 may affect the species proportion in multi-species plant communities.