Influences of elevated ozone and carbon dioxide in growth responses of lowland hay meadow mesocosms

摘要

We studied the effects of relatively low levels of O_3 (40-50 ppb) and CO_2-enrichment (+ 100 ppm) on a northern European lowland hay meadow during the summers 2002—2004 using open-top chambers (OTCs) and ground-planted mesocosms. Ozone reduced the aboveground biomass of the community (up to 40%), and four out of seven species (Campanula rotundifolia, Fragaria vesca, Trifolium medium, Vicia cracca) showed either significant growth reduction and/or visible injuries under elevated O_3. However, the reductions in aboveground biomass were not reflected as changes in the dominance of different functional groups or in the total community root biomass. Elevated CO_2 did not amend the detrimental effects of O_3 on aboveground biomass. Elevated CO_2 alone had only minor effects. An O_3-induced reduction in the aboveground biomass and N pool of the community are likely to have important consequences in the nutrient cycling of the ecosystem.