Do the natural dynamics of West Carpathian forests affect the diversity of epiphytic lichens on Norway spruce?

Over the last decades the West Carpathian spruce and mixed forests with a share of Picea abies, have been un-dergoing intensified dynamic changes, determined by windstorms and European spruce bark beetle outbreaks. Those changes should have a decisive effect on the survivability of species and shifts in epiphytic lichen com-munities on this phorophyte. Research conducted in the Gorce Mts (West Carpathians, Poland) in 1993, 2013 and 2018, on the same 186 spruce trees at 33 sites, revealed an increase in the species diversity of lichen communities in a long-term perspective (25 years). At the same time, there was a decrease in the coverage of the dominant species. Such changes are a result of long-term tree composition processes: the natural thinning of upper mountain spruce forests and the increase of lower mountain forests density after a decrease in the share of Norway spruce. The former prefers photophilous epiphytes, and the latter leads to an increase in the share of shade-tolerant species. The analysis of lichen communities by means of the principal components analysis (PCA) method for all three study periods combined showed that long-term changes were the most significant for this lichen biota, and short-term changes had no considerable effect. The conducted Redundancy Analysis (RDA) revealed, that the forest plant association was a stronger factor affecting the lichen community composition and coverage than tree stand density and saplings density in each observation term. The changes taking place in stands under bark beetle and wind disturbances should be treated differently in different types of forest asso-ciations, but in both, they cause differentiation of niches used by more specialized species of epiphytic lichens.