Per Erik Karlsson,^* Håkan Pleijel,^** David Simpson<sup>***


*</sup>Per Erik Karlsson is an associate professor in plant physiology. His main research interests are variations of air pollutant concentrations and deposition in the landscape and their impacts on forest ecosystems as well as carbon sequestration by forests. His address: Swedish Environmental Research Institute Ltd., P.O. Box 5302, SE-400 14 Göteborg, Sweden. pererik.karlsson@ivl.se
^**Håkan Pleijel is a professor in applied environmental science. His main research areas are the temporal and spatial variation of ozone and other gaseous pollutants in the landscape as well as the effects of ozone and carbon dioxide on vegetation. His address: University of Gothenburg, Plant and Environmental Sciences, P.O. Box 461, SE-405 30 Göteborg, Sweden. hakan.pleijel@dpes.gu.se
^***David Simpson is a senior scientist at the Norwegian Meteorological Institute (MET.NO) and Adjunct Professor at Chalmers University of Technology. He has worked as part of the European Monitoring and Evaluation Programme (EMEP) since 1990, developing the EMEP chemical transport models (CTMs) for ozone, acidification, and particle modeling. Special interests in atmosphere–biosphere exchange include emissions of biogenic hydrocarbons and modeling of the uptake of ozone to vegetation. He is affiliated with the Norwegian Meteorological Institute. His address: Chalmers University of Technology, Department of Radio and Space Science, SE-412 96 Göteborg, Sweden. david.simpson@chalmers.se