Ozone and forests in South-Western Europe

The paper provides basic information about background, objectives and structure of O 3 SWE (Ozone at the permanent monitoring plots in South-Western Europe), an international co-operative project aimed at evaluating O 3 concentrations, cumulative exposure, uptake and effects on forest vegetation in four countries of South-Western Europe (France, Italy, Luxenbourg, Spain and Switzerland). The project covers a total of 83 permanent plots of the EU and UN/ECE intensive forest monitoring programme and span over three years of investigation (2000–2002). The O 3 SWE project aims to demonstrate how, using data collected routinely in an intensive forest monitoring network, O 3 exposure, flux and effects can be assessed and exceedances critically evaluated.