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

Abstract

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.

A recent update in red-listing of Estonian lichens: threat status of 168 species was assessed for the first time

“…In principle, the same concept and the evaluation process as during the previous red list assessments of lichens in Estonia were used (Randlane et al, 2008;. The latest IUCN guidelines for using the Red List categories and criteria ( IUCN Standards andPetitions Subcommittee, 2017, 2019) were applied as well as supplementary guidelines for applying IUCN Red List criteria for fungi (Dahlberg & Mueller, 2011).…”

“…Of them, CR, EN and VU are threatened categories according to the IUCN guidelines. Similarly to the previous assessments (Randlane et al, 2008;, the species that had not been reliably reported from Estonia after 1950 were considered to be RE.…”

“…Two of these, Lathagrium auriforme (found in 1932) and Umbilicaria vellea (found at the beginning of 20 th century), are considered RE in Estonia, while other three are nationally endangered (Appendix 1). In principle, the threat status of Estonian macrolichens has been evaluated during previous assessment periods (Lilleleht, 1998;Randlane et al, 2008, but some macrolichens had been overlooked or were not yet found in the region during previous assessments, such as Catapyrenium daedaleum (Suija et al, 2011).…”

“…Ten years later already 110 lichen species were included in Red Data Book (Randlane, 1998). In these two early Red Data Books of Estonia only macrolichens were evaluated using a conventional system of threat categories while the criteria for defi ning the categories were mainly intuitive-emotional (Lilleleht, 1998;Randlane et al, 2008). In 2008 the international IUCN Red List system of categories together with clearly established criteria was used for the fi rst time in Estonia (Tartes, 2010).…”

“…Altogether 464 lichen species were evaluated then out of the total 1019 lichenized and closely allied fungi recorded nationally at that time. Among evaluated species, mainly macrolichens, 213 were assigned to one of these IUCN categories: Regionally Extinct (RE), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT) or Data Defi cient (DD), while 251 species were assessed as Least Concern (LC) (Randlane et al, 2008). The next round of threat status assessments of Estonian lichens started in 2019 .…”