Trait-based ozone plant sensitivity to assess global vegetation damage risks

A major limitation in modeling global O₃ vegetation damage has long been the reliance on empirical O₃ sensitivity parameters derived from a limited number of species and applied at the level of plant functional types (PFTs), which ignore the large interspecific variations within the same PFT. Here, we present a major advance in large-scale assessments of O₃ plant injury by linking the trait leaf mass per area (LMA) and plant O₃ sensitivity in a broad and global perspective. Application of the new approach and a global LMA map in a dynamic global vegetation model reasonably represents the observed interspecific responses to O₃ with a unified sensitivity parameter for all plant species. Simulations suggest a contemporary global mean reduction of 4.8% in gross primary productivity by O₃, with a range of 1.1%-12.6% for varied PFTs. Hotspots with damages > 10% are found in agricultural areas in the eastern U.S., western Europe, eastern China, and India, accompanied by moderate to high levels of surface O₃. Furthermore, we reveal an inherent plant sensitivity spectrum for O₃ which is highly linked with plant leaf trait trade-off strategy, revealing high risks for fast-growing species with low LMA, such as crops, grasses and deciduous trees.