Differences in gas exchange and antioxidative compounds between young and adult beech trees at the branch and tree level exposed to defined ozone regimes

Wien

2006

Unselbständiges Werk

200134515

The effects of chronic ozone (O3) exposure on beech (Fagus sylvatica) as affected by tree age and crown position were investigated under natural stand conditions in a novel "Free-Air Canopy O3 Exposure" system at Kranzber Forest, Germany. Sixty- and three-year-old beech trees (Fagus sylvatica) were exposed to control (ambient; 1xO3) and enhanced (twice ambient; 2xO3) ozone concentrations. This allowed the comparison of O3 responses between adult trees and seedlings under the same microclimatic conditions. Furthermore, we established a cuvette vice versa experiment in the sun crown to test whether previous results from branch cuvette experiments are representative for whole tree reaction to ozone. The objectives of the study were (a) to present ozone effects on measured gas exchange, pigments and biochemical defence paraqmeters (antioxidants), (b) to address the quesation whether beech seedlings are more sensitive to O3 than adult trees in the field and (c) to clarify if cuvette branches are surrogates for ozone response of entire trees.