| In the context of global warming,ozone pollution in China has gotten worse every year,which has threatened the health of vegetation in China’s terrestrial ecosystem.Ozone would disrupts photosynthesis of vegetation and affects carbon assimilation ability of plants.O3 damage to photosynthesis in China has been quantified in hundreds of measurements but has been limited to individual plant species and specific O3 concentrations.Previous regional modeling of O3 vegetation damage does not always take advantage of valuable observations to calibrate gross primary productivity O3 sensitivity coefficients for terrestrial ecosystems in China,and typically,the derived results have not been properly validated.This leads to significant differences in the estimation results of the same parameter in different regions.The ozone sensitivity coefficient of typical terrestrial ecosystem vegetation types in China were calibrated by BEPSozone model,which coupled with the flux function PODy based on BEPS model(Boreal Ecosystem Productivity Simulator).The total primary productivity(GPP),net primary productivity(NPP)and transpiration(T)of typical terrestrial ecosystems in China were simulated using the newly completed BEPSozone model.The sensitivity of various meteorological factors to GPP,NPP and T was discussed,and the influence of ozone pollution on GPP,NPP and T was quantitatively analyzed.The main conclusions are as follows:(1)The annual average GPP,NPP and T of typical terrestrial ecosystems in China during 2001-2020 were 4.8 Pg C,2.4 Pg C and 248 mm/m2 yr,respectively.The productivity and transpiration increased significantly,with average annual increases of0.04 Pg C,0.01 Pg C and 0.6 mm/m2 yr,respectively.The vegetation type with the highest GPP was evergreen broad-leaved forest,about 1600 g C/m2 yr.The highest NPP was found in evergreen coniferous forest(about 700 mm/m2 yr).The vegetation type with the highest transpiration was evergreen broad-leaved forest,about 640 mm/m2 yr.(2)The impact of ozone in GPP,NPP and T was 5.8%,7.9% and 2.8%,respectively.Warming and increasing carbon dioxide concentrations will further reduce ozone’s effect on vegetation,whereas increased carbon dioxide decreases canopy conductance by about4%.Ozone pollution neutralized 17% of CO2 fertilization over a 20-year period,while synergistic ozone and CO2 decreased canopy conductivity by about 8%.Ozone will also increase respiration by about 1% across vegetation types,resulting in increased autotrophic respiration and increased NPP loss.Ozone pollution has the greatest effect on NPP of evergreen broad-leaved forest,GPP of deciduous broad-leaved forest and transpiration of evergreen broad-leaved forest.(3)Sensitivity analysis based on meteorological factors shows that ozone has a significant negative correlation with both GPP and NPP.Although this effect is not significant for transpiration,it still shows a negative correlation.Light and precipitation are the main controlling factors of GPP and NPP,and have a high positive correlation with GPP and NPP at the national level.Transpiration is affected by radiation and temperature,and precipitation has obvious inhibition effect on transpiration.However,there is a large difference in the whole country,so it needs to be considered in different regions.The main innovations of this study are:(1)the BEPS model is improved on the site scale based on the calibrated ozone sensitivity coefficient of Chinese native vegetation;Optimized the overestimation of GPP in summer;It solved the controversy about the effect of ozone pollution on grassland productivity.(2)Through model simulation,the influence degree of ozone on vegetation respiration and photosynthesis was quantified,the influence mechanism of ozone and climate change on respiration was revealed,and the necessity of coordination of air pollution prevention and control and carbon emission reduction measures was clarified. |
