Effects of Combined CO2 and O3 Exposures on Net CO2 Assimilation and Biomass Allocation in Seedlings of the Late-Successional Fagus Crenata

摘要: We examined the effects of elevated CO2 and O3 concentrations on net assimilation growth Fagus crenata in a screen-aided free-air concentration-enrichment (FACE) system. Seedlings were exposed to ambient air (control), (550 µmol mol−1 CO2, +CO2), (double control, +O3), combination (+CO2+O3) for two growing seasons. The responses light-saturated rates per leaf area (Agrowth-CO2) at each concentration and/or treatments varied widely with age. In older leaves, Agrowth-CO2 was lower presence +O3 than untreated controls, but +CO2+O3 treatment had no effect compared +CO2 treatment. Total plant biomass increased under conditions largest Biomass allocation roots decreased O3. Elongation second-flush shoots also Collectively, these results suggest that contribute enhanced growth; reflecting changes mitigation negative impacts assimilation.