Tropospheric ozone is considered as the most significant phytotoxic pollutant in the atmosphere. While it has been shown that ozone concentrations have significant adverse effects on crop yields, forest growth and species composition, the impacts of ozone on biodiversity are uncertain. The project aims to assess the impacts of O3 on vegetation and biodiversity in Germany. For this purpose, the present study provides (i) a synthesis of current knowledge on the effects of O3 on biodiversity and ecosystem services through a comprehensive literature study and (ii) an analysis of methods and uncertainties in concentration-based and flux-based approaches in O3 risk assessments (critical levels), including validation studies for different vegetation types. Modelling and mapping approaches are used to evaluate the O3 risk for vegetation in Germany at both local and regional scale.