The importance of habitat islands in the preservation of relict xerothermic and calcicolous epigeic lichens based on the example of the “Ostnicowe Parowy Gruczna” nature reserve (N Poland)

The objective of this paper is to discuss the role of environmental islands isolated in the agricultural landscape in the pres- ervation of xerothermic and calcicolous epigeic lichens. The site of lichens associated with relict steppe vegetation, rare in northern Poland, has been preserved in the reserve “Ostnicowe Parowy Gruczna”. The list of lichen taxa identified in the study area comprises 16 species that are very rare in lowland, e.g. Gyalolechia fulgens, Heppia adglutinata, Squamarina lentigera, Endocarpon pusillum, Gyalolechia bracteata, Placidium squamulosum and Toninia sedifolia. In many places, the lichens associated with dry grasslands become extinct despite the optimum light conditions. These lichen species are sensitive to the impact of agriculture. Preservation of epigeic lichens’ localities is possible in specific habitat conditions when they are isolated from surface runoff of fertile farm water