Name:
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- Cladonia, from the Latin
- species, from the Latin
- Cladonia alpestris, from the Latin alpes, "mountains", and
estris,
"origin,
habitat"
- Cladonia arbuscula, from the diminutive of the Latin arbos, "tree";
hence "dwarf tree"
- Cladonia rangiferina
- Cladonia mitis, from the Latin, "ripe, soft"
- Reindeer Moss, from its role as primary food for caribou, known in Europe
as reindeer
- Other common names include: Lichen, Reindeer Moss Lichen, Caribou Lichen
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Taxonomy:
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- Also known as Cladonia stellaris (Cladonia alpestris), Cladonia
sylvatica (Cladonia arbuscula)
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Identification:
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Description:
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- Slow-growing, long-lived, densely branched ground lichens with short numerous
outer branchelets. These lichens often form clumps or mats composed of
a large number of podetia. The podetia are slender, elongated, and branched
in whorls. They are often densely intertangled in large colonies. The slender
thalli of Cladonia rangiferina are hollow stems of very low density
which are finely branched and not only have a high surface to volume ratio,
but also have branches advantageously distributed to carry fire.
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Distribution:
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- Circumpolar; in North America throughout Alaska, Canada, and the northern
United States. south to Florida and Alabama.
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Habitat:
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- Typically occur in submontane to alpine environments. They are scattered
to plentiful in the open or in open-canopy forest and tundra on well-drained,
water-shedding sites with shallow and/or coarse-skeletal soils. In these
environments they often occur on soil and sometimes on rocks, stumps, and
logs.
- Cladonia arbuscula and C. mitis are the most competitive
reindeer lichens on rock. Northern boreal forests offer climatically optimal
conditions for reindeer lichen growth largely because of slow plant succession
and little competition from other plant forms. Dry reindeer lichen woodlands
and lichen bogs are characteristic throughout the northern boreal forest
belt.
- Cladonia rangiferina has a wider ecological amplitude than other
reindeer lichens and is thus more common than the others in less favorable
habitats such as wet bogs and shaded woods. It is very common all over
northern Ontario, being the most widely distributed ground lichen in the
area. Even in the Cladonia alpestris stands of the northern boreal
forest it is considerably more plentiful than C. mitis or C.
arbuscula.
- Cladonia arbuscula prefers a moister and more shaded habitat than
most reindeer lichens but is frequently found mixed with C. mitis.
- C. mitis is commonly one of the dominants on rocks, in lichen woodlands,
and on dry bog hummocks.
- Soils and climate: Reindeer lichens commonly occur on moist to very dry,
sandy, nitrogen-poor soils on shallow humus layers or dry peat. They are
adapted to a cool, moist climate. High relative humidity is especially
important for reindeer lichens.
- Most reindeer lichens avoid calcareous soils and prefer the acid humus
of podzolic soils during germination. Reindeer lichens have been found
on sites with pH values ranging between 4.5 and 5.5.
- Since reindeer lichens are 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.
Reindeer lichens, therefore, can colonize and become a dominant floral
element on soils too shallow or sterile to support higher plants, provided
that humidity is sufficently high for lichen growth and temperature is
sufficently low to inhibit competitors.
- Shade intolerant. Cladonia mitis is an early to mid-seral species,
while C. alpestris, C. arbuscula, and C. rangiferina
are late-seral to climax species.
- C. mitis generally the first reindeer lichen to become established
in postfire white spruce and black spruce stands. It dominates for 30 to
40 years and is then replaced by others such as C. alpestris and
C.
rangiferia.
- If the canopy becomes closed, reindeer lichens are generally replaced
by shade tolerant mosses such as Mountain Fern Moss (Hylocomium
splendens) and Schreber's Feathermoss (Pleurozium
schreberi).
- Reindeer lichens commonly occur as the dominant or codominant ground
cover on open sites dominanted by White Spruce (Picea
glauca), Black Spruce (Picea
mariana), Paper Birch (Betula
papyrifera), or Jack Pine (Pinus
banksiana).
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Fire:
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- Not well adapted to fire; highly flammable and may take 30-100 years or
more to recover to prefire densities.
- Can survive cool fires but are almost always killed by severe fire. In
the black spruce zone, lichens generally burn poorly in early morning or
near sunset, even on hot days, whereas at mid-day they flare up with almost
incredible heat and flame. Humidity changes at ground level and dehydration
appear to be the most likely factors involved. Fifty percent or more may
survive if there is not much organic litter to retain the fire.
- Recover very slowly after fire. Length of recovery time required varies
with species, the extent and intensity of the fires, and site and microclimatic
condition, but an average of 40-50 years appears to be a conservative estimate.
Based on annual growth rates of about 1/8" for C. alpestris and
C.
rangiferina, it has been estimated that these species would require
nearly a century to reach prefire abundance.
- After fire the first reindeer lichen to become established is Cladonia
mitis. The second reindeer lichen phase is generally dominated by C.
alpestris, C. rangiferina, or C. arbuscula.
- Highly flammable. They dry rapidly during periods of low atmospheric humidity
because of the absence of roots, water storage tissues, and low resistance
to water loss. Reindeer lichens resemble dead litter more than live tissue
in their susceptibility to fire. Continuous mats of reindeer lichen present
an uninterrupted surface along which a fire spreads. Lichen mats also accumulate
tree and shrub litter which adds to the flammability.
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Associates:
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History:
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- Cladonia rangiferina is the badge of the Clan McKenzie
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Uses:
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Reproduction:
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- Dispersal mainly by means of thallus fragments and to a much smaller extent
by spores. Wind most important dispersal agent.
- Grow vegetatively by producing new growth annual at the top of the podetium,
which lengthens the internode formed in previous years.
- Podetium passes through three growth stages.
- Growth/accumulation period, lasts an average of 10 years but can vary from
5 to 25 years. During this stage no part of the podetium dies off.
- Growth/renewal period, podetium grows at its highest rate but dies off
at the base at a rate equal to growth. This stage often exceeds 100 years.
- Podetium degeneration period, the podetium dies off at a greater rate than
it grows. This stage may also exceed 100 years.
- Factors that probably contribute to variation in lichen growth include:
the age of the podetium; prior disturbance by animals; and site conditions
such as substrate, drainage, and exposure.
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Propagation:
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Cultivation:
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Links:
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Last updated on 11 October 1999
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