Ozone concentration, exposure and foliar injury in European forests: a ten-year study on permanent monitoring plots

Ground level ozone poses a serious threat to forest ecosystems across Europe and represents a priority for the UNECE Convention on Long-range Transboundary Air Pollution. The ICP Forests Expert Panel on Ambient Air Quality (EP AAQ) has coordinated the monitoring of ozone concentration and effects (i.e. foliar injury on native vegetation) since 2000 on an annual basis on intensive long-term forest monitoring sites across Europe (Level II). Methodologies, including quality assurance such as data harmonization, completeness and plausibility tests have been applied according to the ICP Forests Manual, parts X and XV (Schaub et al. 2010a & 2010b). Here, the authors will evaluate the available data on ozone concentration, exposure and foliar injury that has been collected within the ICP Forests across Europe from approx. 80 – 150 plots and over 1’000 native species. Emphasis will be put on European scale analyses for i) spatial and temporal trends for ozone concentration; ii) AOT40 based on passive samplers and different assessment methodologies; iii) comparison between measured concentration/exposures and EMEP estimates; and iv) foliar injury occurrence in relation to ozone concentration and ozone exposure respectively. When considering the set of stress factors and response indicators monitored within the ICP Forests, this analysis will favor a comprehensive evaluation of ozone risk for European forests