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Species Review

Cetraria islandica, island cetraria lichen

Written
June, 1993
Contributors
Robin F. Matthews - 1st Author

Matthews, Robin F. 1993. Cetraria islandica, island cetraria lichen. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available:https://research.fs.usda.gov/feis/species-reviews/cetisl

DOI
10.2737/feis-species-review-cetisl

AbbreviationCommon NameScientific NameClassificationStatus
Lichens
CETISLisland cetraria lichenCetraria islandicaLife Form: Lichens
Kingdom: Fungi
Class: Lichenized fungi
Order: Lecanorales
Family: Parmeliaceae
Genus: Cetraria
Fed. Protected: No
Nativity: Native
Invasiveness: Noninvasive

Taxonomy

The currently accepted scientific name of island cetraria lichen is Cetraria islandica (L.) Ach. (Parmeliaceae) [10,12,14,19,36]. The following subspecies are recognized [12,36]:

  • Cetraria islandica subsp. islandica, island cetraria lichen
  • Cetraria islandica subsp. crispiformis (Rasanen) Karnef., curly Iceland lichen
  • Cetraria islandica subsp. orientalis (Asah.) Karnef., eastern Iceland lichen

The common name is rarely used for this lichen; therefore, this review uses its scientific name.

Synonyms

  • No entry

Other Common Names

Celand lichen, Iceland-moss

General Distribution

Cetraria islandica is distributed from Canada to Alaska; south to the Pacific Northwest, Wyoming, Colorado, the Great Lakes states, New England, and in alpine regions in the Appalachians to Tennessee [14,17,18].

States and Provinces

  • United States: AK CO CT DE ID ME MD MA MI MN MT NH NY NC OR PA TN VT VA WA WV WI WY
  • Canada: B BC MB NB NF NT NS ON PE PQ SK YT

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].

Plant Communities

Cetraria islandica occurs in various habitats including heaths, dunes, coastal plains, lichen woodlands, bogs, meadows, and tundra [2,4,8,23,34]. In the southern extent of its range, C. islandica is generally restricted to alpine areas [14,43]. Cetraria islandica is a widely distributed species, but generally does not reach ground cover dominance. However, the following publication lists C. islandica as a dominant ground cover species in willow tundra:

  • The Alaska vegetation classification [40]

Common tundra associates of C. islandica include bog Labrador tea (Ledum groenlandicum), crowberry (Empetrum nigrum), prickly rose (Rosa acicularis), bog blueberry (Vaccinium uliginosum), mountain cranberry (V. vitis-idaea), cloudberry (Rubus chamaemorus), bog birch (Betula glandulosa), bunchberry (Cornus canadensis), and willow (Salix spp.). Other associates include bluejoint reedgrass (Calamagrostis canadensis), horsetails (Equisetum spp.), mosses (Hylocomium splendens, Pleurozium schreberi, Sphagnum spp.), sedges (Carex spp.), and other lichens (mainly Cladonia spp.) [11,15,29,37,38].

In arctic coastal plain habitats, C. islandica is found with bluegrass (Poa spp.), purple mountain saxifrage (Saxifraga oppositifolia), sedges (Carex spp.), cassiope (Cassiope spp.), and mountain avens (Dryas spp.) [42].

Photo showing island cetraria growing on rock.
Photo Credit
Photo by Bernd Haynold, CreativeCommons.org, some rights reserved

Island cetraria (CC BY NC-4.0)

Botanical Description

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

Seasonal Development

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].

Photo of island cetraria lichen growing in leave litter.
Photo Credit
Photo © Vladimir Bryukhov, iNaturalist.org, some rights reserved.

Island cetraria (CC BY-NC 4.0)

Successional Status

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 substrata. 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.

Immediate Fire Effects

Cetraria islandica is destroyed by fire [27].

Postfire Regeneration Strategy

  • No entry

Fire Adaptations

Cetraria islandica does not generally occur in recently burned areas [24,27]. Lichens, including C. islandica, are highly flammable under dry conditions because they desiccate as soon as the humidity drops [15].

Plant Response to Fire

In black spruce (Picea mariana)/feathermoss (Pleurozium schreberi)-Cladonia stands in Alaska, C. islandica was present in unburned controls but was not found on burned or fireline sites 9 years after a fire [37]. Cetraria islandica did not survive light or severe burning in the Wickersham Dome Fire near Fairbanks, Alaska. On severely burned black spruce sites, C. islandica was not present in the first 3 years following the fire, although it had control plot frequencies of 60 percent [39]. Cover and frequency percentages on burned mesic black sites in interior Alaska follow [15]:

HabitatYears since fireCoverFrequency
Newly burned0-100
Moss/herb1-5>0.51.0
Tall shrub/sapling5-3000
Dense tree30-55>0.519.0
Mixed hardwood/spruce56-90>0.58.0
Spruce91-200+>0.56.0

Johnson [22], however, states that C. islandica is present in the first years following fire in open and closed black spruce, white spruce (Picea glauca), and jack pine (Pinus banksiana) stands in the Northwest Territories, Canada. It is present throughout seral stages and persists for 200 to 250 years.

Fire Regimes

For information about fire regimes in plant communities where C. islandica may occur, search FEIS by entering the species name on the Advanced Search page and selecting “Fire Regime” as the publication type.

Fire Management Considerations

Lichens often serve as an initial point of ignition in woodlands and tundra and have an essential role in the spread of fire. Lichens dry rapidly during periods of low relative humidity because of their absence of roots, water storage tissue, and low resistance to water loss. Dry lichens resemble dead litter more than live tissue in their susceptibility to fire. Continuous lichen mats present an uninterrupted surface along which fire spreads. Lichen mats typically accumulate tree and shrub litter which adds to flammability [5].

Destruction of forage lichens may have an immediate effect on the winter range of caribou. Lichens may take 70 to 100 years to regain former composition and abundance [31]. However, some studies indicate that fire may increase lichen cover, especially where a thick moss carpet has developed [41]. In the northern boreal lichen belt, lichen forage may be increased by burning sphagnum peatlands, black spruce muskegs, sandy black spruce stands, or tundra heaths. Fires on these sites result in lichen stands in some 40 to 50 years. Because black spruce and mosses regenerate more slowly than lichen on these sites, good lichen growth persists for at least 100 years [3]. Light-severity burning has been suggested as a method of improving reindeer range in Scandinavia [41].

Federal Status

No special status

Other Status

No entry.

Importance to Wildlife and Livestock

Ground lichens provide an important food source in the winter diet of caribou [32]. They provide the major bulk of the winter diet of woodland caribou and are preferred over the more easily accessed arboreal lichens [3]. In Newfoundland, C. islandica is plentiful in lichen stands used by caribou but constitutes less than 5 percent of the lichens ingested [2].

Cetraria spp. are also utilized as forage by reindeer, mountain goat, moose, and muskox [35].

Cetraria islandica is valued as "good" forage for horses and pigs, and has been used as fodder for cattle [33].

Palatability

Cetraria islandica is highly palatable [3].

Nutritional Value

Cetraria islandica is low in protein (estimated at 2 percent) [24,32]. Values of cellulose and lignin concentrations (percent dry weight) from tundra samples collected in June were 1.5 and 2.4, respectively [7]. Cetraria islandica contains a high percentage of lichenin (complex starches) that provides an important source of energy [30].

Cover Value

No enrtry.

Value for Rehabilitation or Restoration of Disturbed Sites

No entry.

Other Uses

Cetraria islandica is one of the few lichens consumed by humans. A powder made from dried C. islandica can be boiled to yield a jelly used in soups in northern Europe. The powder is also used in breads and cereals [33]. The astringent qualities of C. islandica make it useful in tanning leather. It also yields a brown dye [30,33]. Historically, C. islandica has been used to treat coughs, tuberculosis, fevers, and scurvy [1,30,33]. It has traditionally held an important place in Chinese medicine [18]. Cetraria islandica has also been used as a source of antibiotics [1].

Other Management Considerations

The very slow growth rates of ground lichens is widely recognized [3,35]. Growth is estimated at an average of 0.2 inch (0.5 cm) per year [3]. When frequently grazed, ground lichens on winter rangelands may require up to 10 years for full recovery [35]. Cetraria islandica, however, tolerates trampling better than the more abundant reindeer lichens (Cladonia spp.) [2].

In Iceland and Sweden, C. islandica is commercially harvested. Up to 600 pounds is sold each year in Sweden [1]. In Iceland, colonies of C. islandica are harvested every 3 years to allow the lichen to grow to a "profitable size" [33].

After disturbance on Alaskan tundra, C. islandica was present in undisturbed controls and on disturbed sites, even though these sites had been planted with native and nonnative grasses. Cetraria islandica was apparently not inhibited by the competition [9].

Lichens are widely used as indicators of air pollution or air quality. Cetraria islandica exhibits an intermediate sensitivity to sulfur dioxide and to fluoride, and may be useful as an indicator of high concentrations of these chemicals [28]. Lichens, including C. islandica, also absorb radioactive fallout [32].

Mats of C. islandica may diminish seedling establishment [5].

Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.

Forest and Range Ecosystems

  • FRES10 White - red - jack pine
  • FRES11 Spruce - fir
  • FRES18 Maple - beech - birch
  • FRES19 Aspen - birch
  • FRES20 Douglas-fir
  • FRES22 Western white pine
  • FRES23 Fir - spruce
  • FRES24 Hemlock - Sitka spruce
  • FRES25 Larch
  • FRES26 Lodgepole pine
  • FRES28 Western hardwoods
  • FRES44 Alpine

BLM Physiographic Regions

  • 1 Northern Pacific Border
  • 2 Cascade Mountains
  • 8 Northern Rocky Mountains
  • 9 Middle Rocky Mountains
  • 11 Southern Rocky Mountains

Kuchler Plant Associations

  • K001 Spruce - cedar - hemlock forest
  • K002 Cedar - hemlock - Douglas-fir forest
  • K003 Silver fir - Douglas-fir forest
  • K004 Fir - hemlock forest
  • K008 Lodgepole pine - subalpine forest
  • K012 Douglas-fir forest
  • K013 Cedar - hemlock - pine forest
  • K014 Grand fir - Douglas-fir forest
  • K015 Western spruce - fir forest
  • K025 Alder - ash forest
  • K052 Alpine meadows and barren
  • K093 Great Lakes spruce - fir forest
  • K094 Conifer bog
  • K095 Great Lakes pine forest
  • K096 Northeastern spruce - fir forest
  • K106 Northern hardwoods
  • K107 Northern hardwoods - fir forest
  • K108 Northern hardwoods - spruce forest

SAF Cover Types

  • 1 Jack pine
  • 5 Balsam fir
  • 12 Black spruce
  • 13 Black spruce - tamarack
  • 16 Aspen
  • 18 Paper birch
  • 30 Red spruce - yellow birch
  • 31 Red spruce - sugar maple - beech
  • 32 Red spruce
  • 33 Red spruce - balsam fir
  • 34 Red spruce - Fraser fir
  • 35 Paper birch - red spruce - balsam fir
  • 38 Tamarack 107 White spruce
  • 201 White spruce
  • 202 White spruce - paper birch
  • 203 Balsam poplar
  • 204 Black spruce
  • 205 Mountain hemlock
  • 206 Engelmann spruce - subalpine fir
  • 208 Whitebark pine
  • 210 Interior Douglas-fir
  • 212 Western larch
  • 213 Grand fir
  • 215 Western white pine
  • 217 Aspen
  • 218 Lodgepole pine
  • 223 Sitka spruce
  • 224 Western hemlock
  • 225 Western hemlock - Sitka spruce
  • 227 Western redcedar - western hemlock
  • 228 Western redcedar
  • 229 Pacific Douglas-fir
  • 230 Douglas-fir - western hemlock
  • 251 White spruce - aspen
  • 252 Paper birch
  • 253 Black spruce - white spruce
  • 254 Black spruce - paper birch

SRM Rangeland Cover Types

  • No entry

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Last updated February 4, 2026