Distribution and Frequency of Estonian Lichens – Revisited After 25 Years

As of 2024, 1,226 species of lichenized, lichenicolous and systematically related saprophytic fungi have been recorded in Estonia, of which 983 species are lichenized. The species richness of lichenized and related taxa was studied in the five regions of Estonia, with the northwestern mainland region and the western islands region being the two richest in species. The biogeography was surveyed separately for the eastern and western parts of Estonia. 66% of all taxa were present in both regions. The western part was significantly richer in species than the eastern part: 277 species listed in the western part were not found in the eastern regions while only 60 species from the eastern part were not recorded in the west. This corresponds to a major phytogeographical boundary distinguished in Estonia based on the flora and vegetation of higher plants, which runs across the mainland from the northeast to the southwest. Frequency data have also been complemented over the last 25 years. The proportion of rare lichen taxa has decreased, compared to the data in 1999, but Estonian lichen biota is still characterized by a relatively high proportion of rare species (with 1–10 localities) which constituted 43% of all lichens.