ZLV Online

Forests in Central Europe were, and, in certain level, they still are, negatively influenced by air pollution. As the impact of sulphur dioxide decreased significantly, besides acid deposition affecting gradual degradation of the forest soils, mainly ozone could be the most important factor, exceeding ragularly the limits in most of the Czech Republic. The ozone impact on forest stands is rather complicated for many different reasons. This gas is not directly produced – it means the production cannot be easily decreased. In the plant cells no residua of the ozone influence can be revealed – so its impact can be hardly distinguished from the natural oxidation stressors. Its impact on the plants depends on the stomata behaviour – high O3 concentrations in the atmosphere do not necessarily mean high level of damage. Other stressors can either increase or minimise the ozone effects. Mainly for the above mentioned reasons, the risk of increased O3 concentrations for the forest stands still cannot be specified. The article reviews today knowledge of the ozone impact on forest stands, ways of investigation and proving of the changes, and of the possible effect on tree health and timber production. The aim is, besides references survey, to inform on the criteria, including visual assessment of the ozone effect, biochemical and structural markers, which can be used in the monitoring of the ozone impact on forest in Central Europe.