LAUSR

Abstract The study compares the epiphytic lichen communities of two different ecological systems of northern Poland, a non-forested area and a natural lowland deciduous forest corresponding to the potential vegetation flora of a large part of Central Europe, in relation to the same tree species. The impact of habitat type and tree species on individual tree properties and the association between tree size, bark pH, conductivity, water-holding capacity, bark splitting, light intensity at tree trunks and the composition of lichens were analysed. Three sets of lichens were identified: confined to non-forested areas (40 species), confined to forests (61 species), and non-specific mutual species (53 species). The results indicate that most species demonstrate specificity to habitat type rather than to tree species. Factors related to tree species and bark properties gain in importance at the level of a specific habitat. Bark pH and water-holding capacity are decisive factors for lichen occurrence in both habitat types; additionally, in forests, tree diameter is important. The paper provides potentially useful ecological data for campaigns aimed at lichen conservation and at shaping the environment with concern for biodiversity.