## 5 Conclusions  
In this study, climate change, CO\({}_{2}\) and O\({}_{3}\) are integrated into the ecological process model. The single and combined effects of [CO\({}_{2}\)] and [O\({}_{3}\)] on the GPP of woodland ecosystems in China under historical climate change scenarios were investigated by model setting. Our results suggest that CO\({}_{2}\) fertilization is widespread and increasing in woodland ecosystems in China. While ozone damage may currently outweigh the gains in forest productivity of carbon dioxide, rising carbon dioxide and climate change are gradually reducing ozone damage to woodland. Particularly in boreal forest areas, where ozone concentrations are low, there has been a significant increase in GPP. However, simply reducing carbon dioxide emissions could still cause a sustained increase in O\({}_{3}\) damage. This study demonstrates the superiority of ecological process models for assessing interactive responses to climate change. The importance of considering multiple factors in simulation research is emphasized. In addition, the comparison of individual and combined models will provide an important basis for national emission reduction strategies as well as O\({}_{3}\) regulation and climate adaptation in different regions. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/su17167198/s1](https://www.mdpi.com/article/10.3390/su17167198/s1)]([https://www.mdpi.com/article/10.3390/su17167198/s1](https://www.mdpi.com/article/10.3390/su17167198/s1)), Figure S1: Site verification of GPP simulated by BEPS\({}_{\text{O}}_{3}\) model based on flux observation data at sites of different vegetation types. The red is the regression line based on the points, and the blue dotted line is the standard line with slope 1. Figure S2: Verification of seasonal variation of GPP simulated by BEPS\({}_{\text{O}}_{3}\) model based on flux observation data at different vegetation type stations. The red line is the GPP diurnal variation curve of model output, and the blue line is the GPP diurnal variation curve of flux observation stations. Figure S3: Mean daytime O\({}_{3}\) concentrations for 2001s (a) and 2020s (b), and changes in average daily O\({}_{3}\) concentrations between the two periods (c). Figure S4: Plotted interannual changes in mean ozone concentration and atmospheric carbon dioxide concentration in study area, based on historical ozone concentration and carbon dioxide concentration. Figure S5: Mean daily temperature (a,b), radiation (d,e), relative humidity (h,i) and precipitation (k,l) in different periods. And the change of climate factors between the two periods (c,f,j,m). Figure S6: Singly and combined effects of simulated GPP owing to Climate change, [CO\({}_{2}\)], [O\({}_{3}\)]. We calculated the mean value of GPP in different periods and the variation of GPP in different periods. Figure S7: Interannual variation of singly and combined effects of climate change, [CO\({}_{2}\)], [O\({}_{3}\)] on simulated GPP. Figure S8: Interannual changes in canopy conductance and O\({}_{3}\) uptake of woodland ecosystems under different models. The green curves in Figure a and b represent the changes of O\({}_{3}\) uptake and canopy conductance under the condition of E3. The blue curves in Figure a and b represent O\({}_{3}\) uptake and canopy conductance changes of vegetation under E2 conditions. The red curve represents the change of canopy conductance under E4 conditions. Figure S9: Calibration of BEPS for O\({}_{3}\) impacts on plant productivity for each PFT. The dashed line is the regression line through the modeled points, and the solid line is the regression line from the observed dose--response relationship. The x-axis is the cumulative uptake of O\({}_{3}\) (POD1)above the critical O\({}_{3}\) threshold (1 nmol/m\({}^{2}\) s). Because there were no species yield regression curves selected for different climatic zones, there was only one regression line. Table S1: Values of \(\alpha\) for different vegetation types.