The influence of habitat conditions on the formation of species diversity of lichens in urban forests (Petrozavodsk, Republic of Karelia)

The results of the study of the lichen flora of largest green areas of Petrozavodsk that located near the Kurgan ski center are presented. The territory is covered predominantly by feathermoss spruce forests, which have a typical middle-taiga appearance. In 11 forest types, 30 sample plots were established and described, where the lichen diversity was studied. A total of 157 species was recorded that constitutes 50% of the current diversity of Petrozavodsk. The lichen flora includes two species new to the Republic of Karelia, 24 new to Petrozavodsk, three species listed in the Red Data Book of the Republic of Karelia, and another three species included in the list of plant and animal species requiring special attention to their natural environment and recommended for bio-monitoring. Five lichen species are indicators of biologically valuable forests. The results indicate the high biological value of the studied area. The studied lichen flora is presented differently in specific forest communities: the number of lichen species in plots of 0.06 ha varies from 8 to 44, that is, the contribution of the number of species diversity of lichens found in individual sample plots to total lichen flora is only 5–28%. The leading complex characteristic that defines the species composition of lichens is the diversity of forest types, differing in moisture and soil richness. Another active factor is the age of the catastrophic disturbance. Overlapping each other, they lead to the formation of a mosaic of communities with different species composition of lichens. In addition, relatively independent characteristic in this sample is the diversity of substrates, leading to an increase in the species richness of the communities with an increase in substrate diversity. A close relationship was revealed between the species diversity of lichens in a certain type of forest and the size study area.