Welsh Lichen Red List - Lichens of Wales

A Lichen Red Data List for Wales
7. Analysis
7.1 Comparison of Welsh and British
Red Data Lists
Wales, despite being only 11% of the land area of Britain (ie England, Scotland and Wales),
has at one time supported 71% of the total British lichen flora. Table 2 compares the
number of species in each threat category between Britain and Wales. Whilst there is some
comfort in the similar percentages of critically endangered and endangered lichens in
Wales compared to Britain, the significantly larger percentage of vulnerable species is a
cause of grave concern. This extra degree of vulnerability may to some extent be due to
small population sizes partly created by the relatively small size of Wales. There is,
however no doubt that anthropogenic factors have played a large part in reducing
population sizes. Atmospheric pollution by the 1970s had wiped out most of the native
lichen floras from all of south and northeast Wales and grossly affected large parts of
central Wales. This, coupled with wholesale woodland fellings, particularly from the late
1700s through to the Second World War, decimated ancient woodland lichen communities.
Britain
Wales
No. of taxa % of total No. of taxa % of total
Extinct (EX) GB, (EX+RE)Wales 31 2 22 2
Critically Endangered (CR) 42 2 28 2
Endangered (EN) 34 2 24 2
Vulnerable (VU) 105 6 156 12
Near Threatened (NT) 205 11 131 10
Data Deficient (DD) 249 14 152 12
Least Concern (LC) 1168 64 803 61
Total evaluated 1834 1316
Table 2. Number and proportion of taxa in each Red Data List category in Britain and Wales.
7.2 Taxa extinct in Wales
Out of the total of 1316 taxa evaluated from Wales 22 taxa (2%) are thought to have become
extinct. This is similar to the percentage extinction for mainland Britain.
Table 3 below gives the list of extinctions for Wales with the Vice-county and last year each
taxon was recorded.
Whether all of these species are really extinct in Wales must be the subject of some debate. A
species such as Thelocarpon intermediellum is a short lived casual and may occur overlooked
in other sites. The one boulder on which it was reported was removed from the road verge.
Species such as Tomasellia diffusa may still occur on the smooth bark of alder twigs. This is
considered to be a normally rather unproductive habitat by most lichenologists and one rarely
searched with diligence. In contrast mature elm trees, the habitat of Collema fragrans and
Bacidia subincompta in Wales, have largely been felled following their death due to Dutch elm
disease, so their loss is probably genuine.
It is also most likely that species have been lost due to atmospheric pollution throughout the
years of the industrial revolution. By the 1960s large areas of south and north east Wales were
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