Effects of H₂O₂-Containing Acidic Fog on Young Trees

Abstract

Abstract The influence of air pollution on forest die-back in Central Europe is not clarified satisfactorily. Both the ‘acidification-theory’ and the ‘ozone-theory’ as well cannot satisfactorily explain the die-back to its full extent. Some researchers try to link damage patterns to occurrence of fog and ground-based clouds, but laboratory experiments have failed to show serious effects of fog water on trees caused by acidic compounds. The role of reactive compounds such as H2O2, has been overlooked so far. In this work, the effect of hydrogenperoxide-containing fog on young trees is studied. Young spruces and beeches were exposed for three hours per day to acidic fog with concentrations of 1–5 ppm H2O2. After six weeks, serious effects on the internal structure of leaves and needles of H2O2 exposed trees were found. The observed symptoms point towards a decreased resistance to drought and a decreased ability to transport assimilates, which in turn may lead to insufficient nourishment of root elements.