Growth overcompensation against O3 exposure in two Japanese oak species, Quercus mongolica var. crispula and Quercus serrata, grown under elevated CO2

Kitao, Mitsutoshi; Komatsu, Masabumi; Yazaki, Kenichi; Kitaoka, Satoshi; Tobita, Hiroyuki

Growth overcompensation against O3 exposure in two Japanese oak species, Quercus mongolica var. crispula and Quercus serrata, grown under elevated CO2

2015

Kitao, Mitsutoshi | Komatsu, Masabumi | Yazaki, Kenichi | Kitaoka, Satoshi | Tobita, Hiroyuki

To assess the effects of elevated concentrations of carbon dioxide (CO2) and ozone (O3) on the growth of two mid-successional oak species native to East Asia, Quercus mongolica var. crispula and Quercus serrata, we measured gas exchange and biomass allocation in seedlings (initially 1-year-old) grown under combinations of elevated CO2 (550 μmol mol−1) and O3 (twice-ambient) for two growing seasons in an open-field experiment in which root growth was not limited. Both the oak species showed a significant growth enhancement under the combination of elevated CO2 and O3 (indicated by total dry mass; over twice of ambient-grown plants, p < .05), which probably resulted from a preferable biomass partitioning into leaves induced by O3 and a predominant enhancement of photosynthesis under elevated CO2. Such an over-compensative response in the two Japanese oak species resulted in greater plant growth under the combination of elevated CO2 and O3 than elevated CO2 alone.

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