Checklist and Red List of lichens of the Czech Republic

156 Preslia 80: 151–182, 2008
Although these lichens may be locally frequent, the loss of their habitats is continual and
evident, and their potential for dispersal is very limited. Species declining in abundance
that occur also on human-made substrates are mostly included in the NT category.
During a preparatory stage in the compilation of this Red List, changes in the distribution
of certain species were studied in detail (Liška 1994, Liška et al. 1996, 1998a, b, 2006,
Liška & Pišút 1990). For this study, threatened as well as rare lichens of various distributions
in the Czech Republic and degree of sensitivity and frequency, were selected. These
species were compared with other lichens, with similar distributions, sensitivities and potential
threat of habitat change. These studies documented a notable decrease in sensitive
species and significant changes in the distribution of lichens not regarded as endangered
and therefore not red-listed before (e.g., Peltigera horizontalis and P. polydactylon). Detailed
surveys of the distribution changes are published for only 36 lichens, but we were
able to use our experience and these results to evaluate other species.
Of the IUCN criteria, criterion A (observed, estimated or suspected reduction in the
number of individuals) is currently impractical since there is no information on population
size at a particular locality. Therefore, indirect estimates were obtained for readily identifiable
lichens with well documented past distribution. The decline was inferred from the reduction
in the number of localities rather than individuals. This criterion is especially useful
for taxa strongly associated with endangered habitats (old-growth forests, subalpine
vegetation, peat-bogs, limestone outcrops) and used mainly in cases where the lichens
have been mapped in detail (Liška 1994, Liška & Pišút 1990, Liška et al. 1996, 1998a, b,
2006). Criterion B (small geographic range and fragmented area of occupancy, continuing
decline or extreme fluctuations in extent of occurrence, area of occupancy, number of locations
or subpopulations or number of mature individuals) and criterion C (population
size and continuing decline) are used for lichens with a specific ecology (e.g., cupro/ferrophilous,
serpentinicolous and lichenicolous lichens) and species on the edge of their distribution
area. Criterion D (small population size) is the main criterion of species that have
very restricted distribution – last relict occurrences of the boreal-/arctic-montane species
(e.g., Arctoparmelia centrifuga and Leptogium rivale), or rare species confined to specific
habitats at one or a few localities, such as diabase and xerothermic serpentine rocks (e.g.,
Peccania cernohorskyi and Lichinella stipatula). In previous Red Lists these taxa were
classified in category R (rare species). For other, mainly epiphytic species this criterion
was used along with criteria A and/or C, e.g., in cases where the species are conspicuous
but previously rarely recorded (e.g., Heterodermia speciosa and Lobaria amplissima).
These taxa were placed in category CR. Criterion E (probability of extinction) is not applicable,
because data for such an analysis are not available; extrapolation is possible only for
epiphytic lichens where survival is dependent on the presence of a specific substrate (particular
tree) and they are unable to colonize new substrates.
Strict application of category definitions would result in a high proportion of species in
category DD. Including such taxa in the Red List would not increase its information value.
Therefore, species were categorized even when the data were incomplete, by a comparison
with better documented species. In addition, we tried to resolve the problems concerning
the gaps in our knowledge of and changes in the Czech lichen flora by having discussions
with other lichenologists. Nevertheless, changes in distribution have not been evaluated
for some species with poor data, or where there are uncertainties about the reliability of old
records, and such species were included in the category DD (data deficient). Lichens for