Welsh Lichen Red List - Lichens of Wales

A Lichen Red Data List for Wales
CRITICALLY ENDANGERED (CR), ENDANGERED (EN) OR VULNERABLE (VU)
Taxa are considered to be Critically Endangered , Endangered or Vulnerable when any one of the following criteria are met.
A Decline in population size based on any of 1–4. CR EN VU
1) % decline over last 50–100 years where causes of decline are understood, have
ceased and are clearly reversible. >90% >70% >50%
2) % decline over last 50–100 years where causes of decline have not ceased or are >80% >50% >30%
not understood or are not reversible.
3) % decline projected to occur in future. >80% >50% >30%
4) % decline over last 50–100 years added to projected future decline where the
cause of decline has not ceased. >80% >50% >30%
B
Geographic range either as B1 (extent) or B2 (area occupied)
1) Range less than given amount and estimates indicate at least two of the following :- 100 km 2 5000 km 2 20,000 km 2
a) Severely fragmented range or known from no more than the given number
of locations. 1 5 10
b) Decline in extent, area &/or quality of habitat, number of populations - - -
and/or individuals.
c) Extreme fluctuations in extent, area of occupancy or number of locations - - -
or mature individuals.
2) Area of occupancy estimated to be less than given area, and estimates indicating
at least two of a–c. 10 km 2 500 km 2 2000 km 2
a) Severely fragmented or known to exist at no more than a given number of locations. 1 5 10
b) Continuing decline, observed, inferred or projected, in any of the following: - - -
i) extent of occurrence
ii) area of occurrence
iii) area, extent &/or quality of habitat
iv) number of locations or subpopulations
v) number of individuals
c) Extreme fluctuations in any of the following: - - -
i) extent of occurrence
ii) area of occurrence
iii) number of locations or subpopulations
iv) number of individuals
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