Ozone levels in the Jizerske hory Mts. measured at 13 sites by diffusive samplers during the 2006 and 2007 vegetation seasons are presented. A significant ozone gradient (5.4 ppb in 2006 and 4.0 ppb in 2007) per 100 m difference in altitude between 370 and 1,100 m a.s.l. was recorded. High-resolution maps of phytotoxic potential were developed. The AOT40 threshold (5 ppm h) was exceeded over the entire area with the highest levels exceeding this threshold by 12 times in the upper portions of the mountains. Ozone visible injury was evaluated at four of the monitoring sites on seven native plant and tree species. Four species showed ozone-like symptoms, two of which (Rubus idaeus and Fagus sylvatica) were confirmed as ozone-induced. Our results indicate that ambient ozone is likely to have a much lower impact on the Jizerske hory Mts. vegetation than expected, considering the measured ambient ozone exposures and favourable environmental conditions for ozone uptake.

Surface ozone is considered to be a very phytotoxic gaseous air pollutant. Its negative impacts at both the cell and the organ level have been shown, mainly as a result of experiments. However, the demonstration of ozone negative impacts on native plants is not explicit. An assessment of ozone impact on vegetation and ecosystems using indicators based on ambient ozone concentrations is insufficient and assessment techniques based on internal ozone dose and on real plant damage are more appropriate. Such a possible technique is the mapping of ozone visible symptoms due to ozone influence. The ICP-Forest method concerning ozone visible symptoms and the assessment of ozone influence were applied for the purposes of this case study. The visible symptoms are characterized by a few typical signs. Nevertheless, the identification of visible symptoms in native conditions can be problematic and misleading conclusions could be drawn. Therefore it is necessary to complete the identification of visible symptoms with a validation in order to confirm ozone as the cause of plant injury.