BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Cetraria islandica | Iceland Moss 



GENERAL BOTANICAL CHARACTERISTICS : 
Cetraria islandica is a fruticose lichen with a small to medium brown
thallus growing loosely on the soil.  It is usually tufted, many lobed,
and irregularly branched [14,17,18,21].  Colonies are 2 to 8 inches
(5-20 cm) broad.  Apothecia are generally rare [18,36].  Cetraria
islandica exhibits cushionlike growth, making it well suited to weather
high winds in harsh environments.  It imbibes water slowly and can
endure prolonged wet periods [33].  Its phycobiant member is of the
genus Aspicilia which has optimum photosynthetic rates at the low
temperatures found in alpine environments [1].


RAUNKIAER LIFE FORM : 
NO-ENTRY


REGENERATION PROCESSES : 
Cetraria islandica produces ascospores, but sexual reproduction is
infrequent [25].  Reproduction mainly occurs by means of thallus
fragmentation or the dispersal of isidia and soredia.  Wind or animals
may play an important role in the dispersal of these vegetative
propagules [1,27].


SITE CHARACTERISTICS : 
Lichens, including C. islandica, are very dependent on air humidity, and
their abundance is generally in direct relation to the relative humidity
of the climate.  They are better adapted to cold climates than any other
life form.  Lichens grow best in direct sun, and can grow on shallow,
sterile soils [3].  Cetraria islandica is most often found in sandy soil
in exposed areas at high elevations [18].  It commonly grows on moist or
dry tundra among mosses or in the open [36].  Cetraria islandica is also
found on forested sites, nunataks, and rock crevices [17,20,36].
Because C. islandica is able to take up moisture from the air, the
underlying soil is not as important a source of moisture as it is to
vascular plants [3].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Information on the successional status of C. islandica is sparse, and
the available information is conflicting.  Swanson [35] reported that
Cetraria spp. are climax lichens; however, C. islandica is often found
in young lichen stands [2].  Cetraria islandica is also found in seral
floodplain stands in Alaska [38].

Lichens in general decline in productivity in older stands [24].  Ahti
[3] suggests that lichens may be pioneer plants on some sites because
they are dependent on air moisture rather than soil moisture and can
tolerate shallow substratums.  They can persist in environments too
harsh for higher plants, provided humidity is sufficiently high for
lichen growth and temperature is sufficiently low to inhibit
competitors.  Northern boreal forests offer climatically optimal
conditions for lichen growth because of slow plant succession and little
competition from other plant forms.


SEASONAL DEVELOPMENT : 
NO-ENTRY

Related categories for Species: Cetraria islandica | Iceland Moss