Growth onset, senescence, and reproductive development of meadow species in mesocosms exposed to elevated O 3 and CO 2

Abstract

We studied the effects of elevated O 3 (40–50 ppb) and CO 2 (+100 ppm) alone and in combination on the growth onset, relative chlorophyll meter values, and reproductive development of meadow species grown in ground-planted mesocosms using open-top chambers. The 3-year study was conducted in the summers of 2002–2004. Elevated O 3 decreased the early season coverage of plant communities and delayed the flowering of Campanula rotundifolia and Vicia cracca. The relative chlorophyll meter values of Fragaria vesca leaves were decreased by O 3. Ozone also reduced the overall number of produced flowers, but as far as individual species were concerned, O 3 had significant effects only on Campanula rotundifolia. In the case of Fragaria vesca, O 3 decreased the fresh weight of individual berries. The effects of CO 2 were less pronounced, and CO 2 generally did not ameliorate the negative effects of O 3. Changes in reproduction may affect the long-term fate of the whole community.