Abstract
Tropospheric O3 damage to plants significantly affects global vegetation
productivity, yet accurately predicting this damage remains challenging.
This study develops a parameterization to globally predict ozone damage
by integrating a combination of factors: cumulative uptake of ozone
(CUO), O3 concentration, stomatal conductance (Gs), and total exposure
time. We compiled experimental data from over 200 peer-reviewed
publications spanning 50 years, focusing on the responses of various
crops and trees to chronic ozone exposure. Our analysis reveals that
while CUO alone has a weak relationship with changes in photosynthesis
and stomatal conductance under O3 stress, combining CUO with O3
concentration, Gs, and total exposure time significantly strengthens the
predictive power. This combined approach was validated across diverse
categories from experimental data, including plant types, tree age,
exposure systems, types of control air, rooting environments, and ozone
concentration bins. We found photosynthesis exhibited a weaker response
relationship than stomatal conductance, indicative of underlying
responses to O3 stress that could not be captured by the variables and
methods used in this study. Our results underscore the complexity of
predicting O3 damage and highlight the importance of synthesizing
multiple predictors. Future research should incorporate other
environmental stressors, e.g., heat, drought, and elevated CO2 levels,
to enhance the accuracy of O3 damage models. This study provides a
significant advancement in incorporating O3 damage parameterization for
global crop and land surface modeling.