Oaks (Quercus robur) are an important substrate for the epiphytic lichens, especially for red-listed lichens associated with old oaks. These species respond to environmental landscape factors differently at different spatial scales. The effect of environmental and land use factors were tested on the occurrence and richness patterns of lichens species at spatial scales of (28m 1225), in South Eastern Sweden, with differing in landscape characteristics. Our results showed that the three individual tested lichen species and species richness of all the lichens affected differently within the considered scales. The occurrence patterns of lichens Cliostomum corrugatum, Chaenotheca phaeocephala were best explained by the density of oaks within (400m and 302m). However, Ramalina baltica were best explained at smaller scale 263m, but the patterns of species richness was best explained by oak density at (302m). We found that the most important factor on the occurrence and richness patterns of lichens was oak density predicted at almost all the considered scales. However, the three tested lichen species and species richness on oaks also showed positive affect by the circumference. This study concluded that spatial pattern of lichens are now important to understand by different environmental and landscape factors at different spatial scales. Especially, density of oak trees within a stand should be considered to increase the probability of occurrence on other oaks to become colonized. Most of the species are now being red-listed, so, therefore oaks with large circumference in the landscape should be maintained for successful conservation of lichens species.

Key words: old oaks, spatial scales, red-listed lichens, oak density, species occurrence, richness