This diploma thesis deals with two experiments tracking the effects of the tropospheric ozone on vegetation. The first experiment was part of the international project ICP Vegetation in the vegetation season 2008, from July to September in the garden of the Biotechnical Faculty. We observed ozone caused damages to ozone-resistant and ozone-sensitive genotypes of the plants known as the lowgrowing common beans (Phaseolus vulgaris L.). We exposed 10 pots containing the ozone-resistant genotype and 10 containing the ozone-sensitive genotype to natural conditions. The concept of the experiment,the monitoring of the damages to the leaves, the recording of the harvest, the monitoring of the ozone concentration and meteorological parameters were all in accordance with the ICP Vegetation protocol. We assumed that the damages to the leaves of the ozone-sensitive genotype will be greater, their withering premature and their harvest smaller. The results confirmed our assumption. The second part of the experiment took place on the intensive forest monitoring plots as part of the programme ICP-Forest, which is conducted in Slovenia by the Slovenian Forestry Institute, and in this part we observed the ozone-caused damages to the leaves of the trees that are part of the forest vegetation. We also collected the meteorological data for the plots with the help of the Environmental Agency of the Republic of Slovenia and autosamplers. We predicted that ozone-sensitive tree species will suffer more damage and greater damages will occur on those areas where there are either larger sources of ozone precursors in the proximity or a long range air pollutant input. We expected larger damages caused by the ozone in the areas where there are suitable climate conditions for the formation of the tropospheric ozone and damages to plants. The results of our observations confirmed this assumption as well. Smaller damages were also characteristic in the areas with high air temperatures, low humidity and high concentrations of ozone, since in such conditions the input of ozone into plants is disabled due to stomata being closed.