New assessment of Least Concern lichens in the Red List of Estonia: are common species still common?

The threat status of 161 lichenized species that were considered common in Estonia was assessed in 2021. For most of these species, it was the second Red List assessment using the IUCN system (the first such evaluation was performed in 2008). The main data sources for species occurrence were the records reported in 100 study sites located throughout the country during 2020, and the PlutoF biodiversity database. 125 species remained, according to the new assessment, in the category Least Concern (LC) and their populations are not under threat in Estonia at present. Two species were placed in the category Not Applicable (NA) because of systematic revisions while 33 species were assigned to the categories Endangered (EN), Vulnerable (VU) or Near Threatened (NT); one further species received the status Data Deficient (DD). Thus, the threat status has changed for 22% of the studied species that had generally been considered common in Estonia. The reasons for this change are variable but there is clear evidence that 26 species have become more threatened during last 12 years.