Abstract

Keywords

ozone, above-ground part of trees, Methods: differential diagnosis, differential diagnosis

Abstract

During the 1980s and early 1990s, concerns about forest health in central and western Europe were focussed on the impacts of acidic deposition and, to a lesser extent, on gaseous pollutants such as sulphur dioxide. While some interest was also expressed in ozone, difficulties associated with the correct diagnosis of ozone injury to conifers and the high concentrations of ozone that were needed to induce visible damage meant that relatively little attention was paid to ozone as a cause of damage to vegetation. In this publication, we document widespread injury to vegetation in Switzerland induced by ozone. The injury was confirmed in two different studies, using fumigation studies in continuously-stirred tank reactors and filtration studies in open-top chambers. The most typical symptom is reddish brown to purple stippling on the upper surfaces of leaves. However a number of other symptoms were observed, including chlorosis and premature leaf senescence. The extent of visible injury increased with increasing exposure to ozone, and the highest amounts of injury were identified in southern Switzerland (Canton Ticino), which also has some of the highest ozone exposures in the country. Injury was observed on a large number of species and has been reproduced photographically in this guide. The injury was observed exclusively on deciduous broadleaved species. No damage was observed on either evergreen broadleaved species (e.g. Ilex aquifolium L. or Quercus ilex L.) or on coniferous species (e.g. Picea abies (L.) Karst. or Abies alba Miller). This guide is intended to help with the diagnosis of visible injury caused by ozone. However, we would stress the need to confirm diagnoses through careful experimentation under controlled conditions.

LWF Classification

Network: Experimental, LWF, Sites: Lattecaldo, Category: non-reviewed,