Response patterns in adult forest trees to chronic ozone stress:: identification of variations and consistencies

The responsiveness of adult beech and spruce trees to chronic O-3 stress was studied at a free-air O-3 exposure experiment in Freising/Germany. Over three growing seasons, gas exchange characteristics, biochemical parameters, macroscopic O-3 injury and the phenology of leaf organs were investigated, along with assessments of branch and stem growth as indications of tree performance. To assess response pattern to chronic O-3 stress in adult forest trees, we introduce a new evaluation approach, which provides a comprehensive, readily accomplishable overview across several tree-internal scaling levels, different canopy regions and growing seasons. This new approach, based on a three-grade colour coding, combines statistical analysis and the proficient ability of the human eye in pattern recognition. (c) 2005 Elsevier Ltd. All rights reserved.