Ozone-induced changes in the relationship between photosynthesis (A_n) and stomatal conductance (g_s) vary among species, leading to inconsistent water use efficiency (WUE) responses to elevated ozone (O₃). Thus, few vegetation models can accurately simulate the effects of O₃ on WUE. Here, we conducted an experiment exposing two differently O₃-sensitive species (Cotinus coggygria and Magnolia denudata) to five O₃ concentrations and investigated the impact of O₃ exposure on predicted WUE using a coupled A_n-g_s model. We found that increases in stomatal O₃ uptake caused linear reductions in the maximum rates of Rubisco carboxylation (V_cmax) and electron transport (J_max) in both species. In addition, a negative linear correlation between O₃-induced changes in the minimal g_s of the stomatal model (g₀) derived from the theory of optimal stomatal behavior and light-saturated photosynthesis was found in the O₃-sensitive M. denudata. When the O₃ dose-based responses of V_cmax and J_max were included in a coupled A_n-g_s model, simulated A_n under elevated O₃ were in good agreement with observations in both species. For M. denudata, incorporating the O₃ response of g₀ into the coupled model further improved the accuracy of the simulated g_s and WUE. In conclusion, the modified V_cmax, J_max and g₀ method presented here provides a foundation for improving the prediction for O₃-induced changes in A_n, g_s and WUE.

臭氧诱导的光合作用（A _n）与气孔导度（g _s）之间的关系变化在物种之间有所不同，从而导致对升高的臭氧（O ₃）的用水效率（WUE）响应不一致。因此，很少有植被模型可以准确地模拟O ₃对WUE的影响。在这里，我们进行了一项实验，将两种对O ₃敏感的不同物种（Cotinus coggygria和Magnolia denudata）暴露于五个O ₃浓度，并使用耦合的A _n - g _s研究了O ₃暴露对预测WUE的影响_。模型。我们发现，气孔O ₃吸收的增加导致两种物种的Rubisco羧化最大速率（V _cmax）和电子传递（J _max）线性降低。另外，在对O ₃敏感的M. denudata中，从最佳气孔行为理论推导的气孔模型最小g _s（g ₀）中O ₃引起的变化与光饱和光合作用之间呈负线性相关。。当基于O ₃剂量的V _cmax和J _max响应时包括在一个耦合的A _n - g _s模型中，在升高的O ₃下模拟的A _n与这两个物种的观察结果都非常吻合。对于天竺葵，将g ₀的O ₃响应合并到耦合模型中，可以进一步提高模拟g _s和WUE的准确性。总之，本文介绍的改进的V _cmax，J _max和g ₀方法为改善O ₃引起的A变化的预测提供了基础。_n，g _s和WUE。