Epidemiological derivation of flux-based critical levels for visible ozone injury in European forests

Abstract

none ; 11 ; Funding text #1 This work was carried out with the contribution of the LIFE financial instrument of the European Union in the framework of the MOTTLES project "Monitoring ozone injury for setting new critical levels" (LIFE15 ENV/IT/000183) and the technical support by: Ecrins National Park, Morvan Regional Natural Park, Electricity of France, certified Associations of Air Quality Monitoring (Atmosf'air Bourgogne, Atmo Grand-Est, Atmo Auvergne-Rhône-Alpes, Atmo Nouvelle-Aquitaine), the MERA Programme, funded by the French Ministry for Ecological and Solidary Transition, Comando Unità Forestali, Abientali e Agroalimentari Carabinieri (CUFA) and all the Institutions managing the Italian and Romanian sites. Funding text #2 Project funding: This work was supported by the LIFE financial instrument of the European Union in the framework of the MOTTLES project "Monitoring ozone injury for setting new critical levels" (LIFE15 ENV/IT/000183). ; The European MOTTLES project set-up a new-generation network for ozone (O3) monitoring in 17 plots in France, Italy and Romania. These monitoring stations allowed: (1) estimating the accumulated exposure AOT40 and stomatal O3 fluxes (PODY) with an hourly threshold of uptake (Y) to represent the detoxification capacity of trees (POD1, with Y = 1nmolO3m−2s−1per leaf area); and (2) collecting data of forest-response indicators, i.e. crown defoliation and visible foliar O3-like injury over the time period 2017–2019. The soil water content was the most important parameter affecting crown defoliation and was a key factor affecting the severity of visible foliar O3-like injury on the dominant tree species in a plot. The soil water content is thus an essential parameter in the PODY estimation, particularly for water-limited environments. An assessment based on stomatal flux-based standard and on real plant symptoms is more appropriated than the exposure-based method for protecting vegetation. From flux-effect relationships, we derived flux-based critical levels (CLef) for ...