Tolerance of the lichen Xanthoria parietina (L.) Th. Fr. to metal stress

Comparisons were made between the content of Al, Cd, Cu, Fe, Mn, Pb, Sb and Zn in thalli of the lichen Xanthoria parietina and selected physiological processes. Assimilation pigments, activity of photosystem II, parietin, reactive substances produced using thiobarbituric acid (TBA) and CO2 gas exchange were measured in order to assess tolerance to atmospheric sources of pollution. As expected, lichen thalli accumulated high amounts of the measured elements in relation to distance from pollution sources in Košice, Slovak Republic (US Steel factory and vehicular traffic in the city center). However, except for TBA reactive substances production and to some extent CO2 gas exchange at the most polluted station, none of the tested physiological parameters showed a clear correlation between accumulation of elements and physiological damage. This reflected a high degree of pollution tolerance in this lichen and corresponded with its high abundance in Košice.