Tropospheric ozone (O 3 ) concentration has been increasing. The aim of this study was to compare the effect of O 3 exposure on monoterpene emission rate and the components of Japanese cedar (Cryptomeria japonica) between three major gene pools identified by population genetic structure analysis. At the O 3 -FACE (Free-Air O 3 and CO 2 Enrichment) facility, 1-year saplings of three clones of Japanese cedar (Donden, Kawazu, and Yakushima) were exposed to ambient double concentrations of O 3 .

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... er 15 months of O 3 exposure experiment, monoterpene emission characteristics were evaluated by branch enclosure method using cutting samples of current-year leaves. Basal biogenic volatile organic compound emission rate (E s ) was higher in the O 3 exposure plots, and two-way analysis of variance revealed an effect of the O 3 exposure ( p < 0.05) and an interaction between the O 3 exposure and clone ( p < 0.05). Especially, high E s values were observed in the Yakushima after the O 3 exposure. In addition, the coefficient β related to temperature sensitivity increased in the O 3 exposure plots ( p < 0.05). Our findings supported the fact that there are large inter-clone variations in C. japonica. It is important to evaluate the differences in clones considering the genetic diversity and to clarify the mechanism of the differences after long-term moderate O 3 exposure.