Exploring new strategies for ozone-risk assessment: A dynamic-threshold case study

Tropospheric ozone is a dangerous atmospheric pollutant for forest ecosystems when it penetrates stomata. Thresholds ozone-risk assessment are based on accumulated stomatal fluxes such as the Phytotoxic Ozone Dose (POD). In order to identify effect of Holm oak in central Italy, four flux-based impact response functions were implemented and tested multi-layer canopy model AIRTREE evaluated against Gross Primary Productivity (GPP) obtained from observations Eddy Covariance CO2. To evaluate if clear phytotoxic threshold exists changes during year, six different detoxifying thresholds ranging between 0 5 nmol O3 m−2 s−1 tested. The use species-specific rather than more general plant functional types (PFT) increased accuracy (RMSE reduced by up 8.5%). case linear functions, 1 s−2 produced best results simulations whole although tolerance changed seasonally, with higher (5 or no impact) Winter Spring lower Summer Fall (0–1 s−1). A “dynamic threshold” extracting daily values range helped reduce overestimation GPP 213 g C y−1 RMSE 7.7%. Finally, nonlinear correction manipulative experiments was applied (0 s−1), suggesting that fully account detoxification. evidence seasonal points need predict damage highlights importance performing derive broad species.