Fluxes of N_2O, CH_4 and CO_2 in a meadow ecosystem exposed to elevated ozone and carbon dioxide for three years

摘要

Open-top chambers (OTCs) were used to evaluate the effects of moderately elevated O_3 (40-50 ppb) and CO_2 (+ 100 ppm) and their combination on N_2O, CH_4 and CO_2 fluxes from ground-planted meadow mesocosms. Bimonthly measurements in 2002-2004 showed that the daily fluxes of N_2O, CH_4 and CO_2 reacted mainly to elevated O_3, while the fluxes of CO_2 also responded to elevated CO_2. However, the fluxes did not show any marked response when elevated O_3 and CO_2 were combined. N_2O and CO_2 emissions were best explained by soil water content and air and soil temperatures, and they were not clearly associated with potential nitrification and dentrification. Our results suggest that the increasing O_3 and/or CO_2 concentrations may affect the N_2O, CH_4 and CO_2 fluxes from the soil, but longer study periods are needed to verify the actual consequences of climate change for greenhouse gas emissions.