## 3 Results  
Table 1 shows the air temperature, VPD and PPFD inside the chambers during the O\({}_{3}\)-exposure periods from 26 April to 22 November 2012 and from 29 March to 14 November 2013. The climatic conditions inside the OTCs were similar during the exposure periods of 2012 and 2013. Table 2 shows the average O\({}_{3}\) concentrations and AOT40 of O\({}_{3}\) in each gas treatment during the O\({}_{3}\)-exposure periods of 2012 and 2013. The exclusion efficiency of O\({}_{3}\) in the CF treatment was about 80%. Averaged across the two growing seasons, even though the seasonal mean O\({}_{3}\) concentrations in the 1.5\(\times\) and 2.0\(\times\)O\({}_{3}\) treatments were 1.62-1.74 and 2.19-2.33 times higher than that in the 1.0\(\times\)O\({}_{3}\) treatment, respectively, the highest 1-h maximum O\({}_{3}\) concentration in the two treatments almost reached the target concentration (i.e., 1.53 and 2.02 times, respectively). The average concentration in 2012 was lower than that in 2013, whereas the daily 1-h maximum concentration was higher in 2012 than in 2013. Although this result suggests a stronger diel pattern in 2012, it was not obvious. The daylight AOT40 in the 1.0 \(\times\) O\({}_{3}\) treatments in 2012 and 2013 were 6.0 and 7.5 ppm h and exceeded the concentration-based critical level for O\({}_{3}\)-sensitive forest trees (5 ppm h) that was adopted by the United Nations Economic Commission for Europe Convention on Long-Range Trans-boundary Air Pollution [18]. To test the performance of stomatal conductance model for the leaves of _F. crenata_, _Q. serrata_, _Q. mongolica_ var. _crispula_ and _B. plattyphyllla_ var. _japonica_ seedlings, linear regression analyses were conducted between measured \(g_{\mathrm{sw}}\) and \(g_{\mathrm{sw}}\) estimated from the model of [PERSON] et al. (2014) [27], with modifications of \(g_{\mathrm{max}}\) and the parameters of each function (Table 3). The model parameterized in the present study accounted for 48.2% of the variation in the 1 st flush leaves of _F. crenata_, 41.6% and 34.7% of the variation in the 1 st and 2 nd flush leaves of _Q. serrata_, respectively, 34.6% and 20.9% of \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Period**} & \multicolumn{4}{c}{**Air Temperature (\({}^{\circ}\)C)**} & \multicolumn{4}{c}{**VPD (\& \& **\& **PFD**)} & \multicolumn{2}{c}{**PFFD**} \\ \cline{2-11}  & **Daily Mean** & **Daily Max.\({}^{\circ}\)** & **Daily Min.\({}^{\circ}\)b** & **Daily Mean** & **Daily Max.\({}^{\circ}\)** & **(mol m\({}^{-2}\) day\({}^{-1}\))** \\ \hline
26 Apr-22 Nov., & 19.4 & (0.1) & 25.0 & (0.3) & 15.2 & (0.0) & 0.41 & (0.03) & 1.28 & (0.06) & 16.9 & (0.2) \\
2012 & 29 Mar-14 Nov., & 19.1 & (0.1) & 25.2 & (0.3) & 14.6 & (0.1) & 0.43 & (0.04) & 1.32 & (0.09) & 16.8 & (0.3) \\
2013 & & & & & & & & & & & & \\ \hline \hline \end{tabular} Each value is the mean value of 12 OTCs; the standard deviation is shown in parentheses. \({}^{\circ}\) Mean daily 1-h maximum value. \({}^{\circ}\) Mean daily 1-h minimum value.  
\end{table} 
Table 1: Seasonal means of air temperature, vapor pressure deficit (VPD), and photosynthetic photon flux density (PPFD) inside open-top chambers (OTCs) during the O\({}_{3}\)-exposure period in 2012 and 2013. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Period**} & \multirow{2}{*}{**Treatment**} & \multicolumn{4}{c}{**Concentration (nl l\({}^{-1}\))**} & \multirow{2}{*}{**Daylight**} \\ \cline{3-11}  & & & \multicolumn{4}{c}{**Seasonal Mean**} & & & **Highest** & **AOT40 \({}^{\circ}\)b** \\ \cline{3-11}  & & **24-h Mean** & **12-h Mean\({}^{\circ}\)** & **1-h Max. ** & **1-h Max.