Welsh Lichen Red List - Lichens of Wales

Rhestr o Gen Data Coch ar gyfer Cymru
C Population size estimated to number fewer than the given number of individuals CR EN VU
(an individual generally taken to be tree number for epiphytic species or discrete units
of rock for epilithic taxa) and either:- 250 2500 10,000
1) An estimated continuing decline of the given percentage in up to the last
100 years or 25% 20% 10%
2) An estimated decline observed or inferred in number of individuals
(see above for definition of individual) and at least one of the following:-
a) Population structure in form of one of the following:i)
no sub population estimated to contain more than the given number of
mature individuals or 50 250 1000
ii) at least the given % of mature individuals in one subpopulation. 90% 95% 100%
b) Extreme fluctuations in number of mature individuals (see above for definition - - -
of individual).
D Population size estimated to number fewer than the given number of mature
individuals (see above for definition) (D or D1). Or in the case of species considered
for Vulnerable status, its population occupying a very restricted area (typically 5 or
fewer locations) so rendering it vulnerable to extinction (D2). 50 250 1000
E Probability of extinction is at least the given % within the next 100 years. 50% 20% 10%
Table 1. Criteria used in Wales for evaluating species and deciding on their IUCN Red List
category
NEAR THREATENED (NT)
A taxon is Near Threatened when it is has been evaluated against the criteria but does not
qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying
for or is likely to qualify for a threatened category in the near future.
LEAST CONCERN (LC)
A taxon is Least Concern when it has been evaluated against the criteria and does not
qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened.
Widespread and abundant taxa are included in this category.
DATA DEFICIENT (DD)
A taxon is Data Deficient when there is inadequate information to make a direct, or
indirect, assessment of its risk of extinction based on its distribution and/or population
status. Whilst Data Deficient could be considered not to be a category of threat, in
practice it must be a matter of grave concern that a threat status cannot be assigned.
Some of these species could be critically endangered. Consequently a high priority
should be attached to securing resources to further investigate these species.
NOT EVALUATED (NE)
A taxon is Not Evaluated when it has not yet been evaluated against the criteria. There
can be many reasons for this. Often it is due to some taxonomic issue.
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