Western redcedar (Thuja plicata), also called Pacific redcedar, giant-cedar, arborvitae, canoe-cedar, and shinglewood, is the only Thuja species native to western North America. Extant redcedar volumes are estimated to be 824 million m³ (29 billion ft³) in British Columbia (43) and 228 million m³ (8 billion ft³) in the United States (16). Most of this volume is in mature trees, which have tapered, often-fluted bases, drooping branches, thin fibrous bark, and small scalelike leaves arrayed in flat sprays. Many have forked tops. They often reach ages of 800 to 1,000 years. One particularly large specimen in Washington has a d.b.h. of 592 cm (233 in), a height of 54.3 m (178 ft), and a crown spread of 16.5 m (54 ft). The wood is valuable and extensively used in a wide variety of products.
General: Cypress family (Cupressaceae). Native trees growing to 50 (-75) meters tall, often buttressed at base, with a conical to irregular crown, old individuals frequently with many leaders and many dead spike tops; branches arching, branchlets pendent, flattened, in fan-shaped sprays; bark gray to reddish-brown, 10-25 mm thick, fibrous, separated into flat, connected ridges. Leaves are evergreen, scale-like and sharply pointed, (1-) 3-6 mm long, opposite in alternating pairs (in 4 rows), glossy green above, white-striped on the lower surface, with a spicy fragrance when crushed. Seed cones are ellipsoid, 10-14 mm long, brown; seeds 8-14 per cone, 4-7.5 mm long, with lateral wings about as wide as the body. The common name pertains to the western distribution and cedar-like appearance.
Variation within the species: although small inter-populational differences have been documented, western red-cedar seems to show less within-species genetic variation than other northwestern conifers. Horticultural varieties with color and growth form differences have been developed (atrovirens, fastigiata, pendula).
Distribution: The range of western red-cedar is essentially in two segments: a Coast Range-Cascade Range segment from southeastern Alaska to northwestern California and a Rocky Mountain segment from British Columbia and Alberta to Idaho and Montana. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Giant arborvitae, western arborvitae, giant red-cedar, Pacific red-cedar, shinglewood, canoe cedar
Regularity: Regularly occurring
Regularity: Regularly occurring
Global Range: Limited to Pacific Northwest of North America.
Occurrence in North America
of the Alaska Panhandle through British Columbia, western Washington,
and western Oregon, reaching into the coastal redwood forest of northern
California [8,50,54,57]. Inland from the coast it occupies a contiguous
band east of the Cascade Range from central Oregon to southern British
Columbia . Much farther inland a disjunct population occurs along
the west slopes of the Rocky Mountains from Prince George, British
Columbia, to northeastern Washington, northern Idaho, and western
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
1 Northern Pacific Border
2 Cascade Mountains
5 Columbia Plateau
8 Northern Rocky Mountains
North of the Olympic Peninsula and Vancouver Island, the coastal range narrows again and is restricted to the Coast Ranges and offshore islands. A few scattered stands are found between the Coast Ranges and the Selkirk Mountains near the southern border of British Columbia, but redcedar's coastal range is essentially isolated from its interior range.
The interior range extends south from the western slope of the Continental Divide at latitude 54° 30' N. in British Columbia through the Selkirk Mountains into western Montana and northern Idaho (2). The southern limit is in Ravalli County, MT (lat. 45° 50' N.). With the possible exception of a few trees east of the Continental Divide near the upper end of St. Mary Lake, Glacier County, the eastern limit of the range of redcedar is near Lake McDonald in Glacier National Park, MT.
- The native range of western redcedar.
The trees occur on various substrates, commonly on moist sites (swamps, wet ravines, poorly drained depressions), but on a variety of landforms, including rocky slopes, at 0-1500 (-2300) meters elevation. They usually occur in mixed coniferous forests, rarely in pure stands. In cultivation, they prefer moist, acid, well-drained soils but have been grown in heavy clays of the Midwest.
Western redcedar is a large, native, long-lived, evergreen tree
[8,50,57,80]. At maturity it is generally 70 to 100 feet (21-30 m)
tall, sometimes 130 feet (40 m), with a tapering trunk 2 to 4 feet
(0.6-1.2 m) in diameter, sometimes 6 feet (1.8 m) or more. On some
sites west of the Cascades, old-growth western redcedar often attains
basal diameters of 8 to 10 feet (2.4-3 m) and heights of 200 feet (61
m). The largest known western redcedars are believed to be 1,000 years
old or more .
Western redcedar has a swollen or buttressed base, pointed conical
crown, and horizontal branches curving upward at the tips . The
leaves are scalelike, flattened and 0.05 to 0.1 inches (1.5-3 mm) long.
The twigs are flattened, in fanlike sprays and slightly drooping. The
bark is thin, fibrous and stringy or shreddy. Thickness varies from 0.5
to 1 inch (1.3-2.5 cm) . The cones are
clustered near the ends of
twigs and become turned up on short stalks . Western redcedar
retains its lower limbs except when in densely crowded stands .
Western redcedar roots are extensive. Tap roots are poorly defined or
nonexistent, but fine roots develop a profuse, dense network. Root
systems tend to be shallower and less extensive on wet soils than on
deep, moderately dry soils. When a thick duff layer is present, many
western redcedar roots lie in the duff rather than in the underlying
Habitat and Ecology
Comments: Wet coastal forests.
Western redcedar grows best in maritime climates with cool, cloudy
summers and wet, mild winters. In drier areas west of the Cascades,
western redcedar becomes abundant only on wet sites such as ravines,
along streams, or on poorly drained bottomlands. Near its range limits
in the drier mountains east of the Cascade crest, western redcedar grows
almost exclusively in narrow canyons, where its roots are irrigated all
summer by a mountain stream . In Glacier National Park and the
Selway-Bitterroot Wilderness in Idaho and Montana, western redcedar is
dominant in wet ravines and poorly drained depressions .
Precipitation and temperature: Western redcedar occurs on sites that
receive from 35 inches (890 mm) of annual precipitation to more than 260
inches (6,600 mm), mostly as winter rainfall . Western redcedar is
not resistant to frost and is sometimes damaged by freezing temperatures
in late spring or early autumn. When sufficient precipitation is
present, low temperatures appear to limit western redcedar's range. The
northern limits of western redcedar lie between the 52 and 53 degree
Fahrenheit (11.1-11.7 deg C) mean summer temperature isotherms in
southeastern Alaska . Bottomland frost pockets in northern Idaho
are commonly occupied by subalpine fir (Abies lasiocarpa) rather than
western redcedar .
Soils: Western redcedar can tolerate a wide range of soil. It is found
on all soil textures and parent materials on Vancouver Island. Coarse
sandy soils are not well suited to the establishment and growth of
western redcedar in northern Idaho and northeast Washington, but rocky
slopes with limited soil development support western redcedars in
southeastern Alaska. Poorly drained organic soils support redcedar
south of Petersburg, Alaska. It grows well on shallow soils over chalk
and can tolerate both acid and alkaline soils conditions. It is able to
survive and grow on soils that are low in nutrients and is found on such
soils over much of its natural range. However, productivity may be
improved by fertilization .
Elevation: Elevational ranges of western redcedar have been reported as
Alaska - 0 to 3,000 feet (0-910 m)
British Columbia - 0 to 3,900 feet (0-1,190 m)
Oregon - 0 to 7,500 feet (0-2,290 m)
northern Rocky Mountains - 2,000 to 5,900 feet (610-1,798 m)
In coastal regions, western redcedar is commonly associated with the
following shrub and herb species: dwarf Oregon grape (Mahonia nervosa),
stink currant (Ribes bracteosum), Alaska blueberry (Vaccinium
alaskaense), box blueberry (V. ovatum), Pacific rhododendron
(Rhododendron macrophyllum), salal (Gaultheria shallon), threeleaf
anemone (Anemone deltoidea), deerfern (Blechnum spicant), slough sedge
(Carex obnupta), and evergreen violet (Viola sempervirens) [50,51].
In interior regions western redcedar is commonly associated with the
following shrub and herb species: mountain alder (Alnus incana spp.
tenuifolia), Oregon grape (Mahonia repens), common juniper (Juniperus
communis), red raspberry (Rubus idaeus), blue huckleberry (Vaccinium
globulare), Rocky Mountain honeysuckle (Lonicera utahensis), gold thread
(Coptis occidentalis), roundleaf alumroot (Heuchera cylindrica), pine
drops (Pterospora andromedea), and green pyrola (Pyrola chlorantha)
Common shrub and herb associates of both coastal and interior regions
are as follows: western serviceberry (Amelanchier alnifolia),
thimbleberry (Rubus parviflorus), oceanspray (Holodiscus discolor),
Devil's club, common snowberry (Symphoricarpos albus), lady fern,
western swordfern (Polystichum munitum), prince's-pine (Chimaphila
umbellata), bunchberry dogwood (Cornus canadensis), false Solomon's-seal
(Smilacina stellata), and Pacific trillium (Trillium ovatum) [50,51].
Key Plant Community Associations
Western redcedar commonly occurs as a dominant or codominant on
low-elevation moist sites. In Montana, the western redcedar habitat
type series described by Pfister and others  occurs most extensively
in the Swan Valley and Mission Range, extends eastward locally to
Missoula, and forms small riparian stringers along major streams in the
Bitterroot Range west of Hamilton. Western redcedar occurs as a
riparian dominance type on toe-slope seepages, moist benches, and wet
bottoms adjacent to streams . Daubenmire and Daubenmire 
recognized three western redcedar communities in northern Idaho.
Western redcedar/pachistima (Pachistima myrsinites) is an upland
community, while western redcedar/Devil's club (Oplopanax horridus) and
western redcedar/ladyfern (Athyrium filix-femina) occur on bottomlands.
Western redcedar is sometimes found as a codominant with western hemlock
(Tsuga heterophylla) [16,35,60]. Published classifications identifying
western redcedar as a dominant or codominant are as follows:
Old-growth forests of the Canadian Rocky Mountains National Parks .
Preliminary plant associations of the southern Oregon Cascade Mountain
Classification and management of riparian and wetland sites in
northwestern Montana .
Forest habitat types of northern Idaho: a second approximation .
Forest Vegetation of eastern Washington and northern Idaho .
Fire ecology of Lolo National Forest habitat types .
Preliminary forest plant association management guide. Ketchikan area,
Tongass National Forest .
Fire ecology of western Montana forest habitat types .
A guide to the interior cedar-hemlock zone, northwestern transitional
subzone (ICHg), in the Prince Rupert Forest Region, British Columbia
Riparian dominance types of Montana .
Classification and management of riparian sites in southwest Montana
Soil classification as an aid to identifying forest habitat types in
northern Idaho .
Forest habitat types of Montana .
Reference material Daubenmire habitat types .
Preliminary forest plant associations of the Stikine area, Tongass
National Forest .
A study of the Vegetation of southeastern Washington and adjacent Idaho
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce
FRES26 Lodgepole pine
FRES28 Western hardwoods
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
210 Interior Douglas-fir
212 Western larch
213 Grand fir
215 Western white pine
218 Lodgepole pine
221 Red alder
222 Black cottonwood - willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock - Sitka spruce
226 Coastal true fir - hemlock
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - Douglas-fir forest
K004 Fir - hemlock forest
K005 Mixed conifer forest
K006 Redwood forest
K012 Douglas-fir forest
K013 Cedar - hemlock - pine forest
K014 Grand fir - Douglas-fir forest
K015 Western spruce - fir forest
Soils and Topography
Western redcedar seems able to survive and grow on soils that are low in nutrients and is found on such soils over much of its natural range. Site index is positively correlated with foliar nitrogen, sulfur, copper, boron, and chlorophyll. However, productivity may be improved by fertilization (44). When grown in well watered soil fertilized with nitrogen, phosphorus, and potassium, redcedar seedlings outgrow the seedlings of Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis), Sitka spruce (Picea sitchensis), western hemlock, and ponderosa pine (Pinus ponderosa). Available nitrogen, calcium, and water appear to be the most important factors affecting growth and establishment of redcedar. Established redcedars tend to raise soil cation exchange capacities, pH's, and amounts of exchangeable calcium (1) and thus benefit the soils in which they grow.
Western redcedar grows from sea level to 910 m (3,000 ft) in southeastern Alaska. In British Columbia, the elevational range is higher-from sea level to 1190 m (3,900 ft). Redcedar is found in the interior from 320 m (1,050 ft) to 2130 m (7,000 ft).
The greatest range in elevation occurs in Oregon, where the species occurs from sea level to 2290 m (7,500 ft) at the rim of Crater Lake.
Although western redcedar is abundant in many forested swamps, it is sometimes found on sites that are too dry for western hemlock (Tsuga heterophylla) (12,39,42), probably because the root penetration of the redcedar is better. Redcedar leaves are not protected from excessive transpiration by cutin and wax.
Trees tolerate stagnant winter water tables averaging less than 15 cm (6 in) below the soil surface on the Olympic Peninsula (32). The species dominates wet ravines and poorly drained depressions in both Glacier National Park in Montana and the Selway Bitterroot Wilderness in Idaho (20,21).
Where sufficient precipitation is present, low temperature appears to limit the species' range. Length of the frost-free period abruptly decreases just above the tree's upper elevation limits on Vancouver Island. The northern limits of western redcedar lie between the 11.1° and 11.7° C (52° and 53° F) mean summer temperature isotherms in southeastern Alaska. Absolute minimum temperatures experienced by western redcedar in British Columbia are -10° to -30° C (14° to -22° F) in coastal populations, -14° to -47° C (7° to -53° F) in the interior (28). Western redcedar has a growing season of at least 120 frost-free days along the coast but as few as 75 frost-free days in some portions of its interior range. It is not resistant to frost and is sometimes damaged by freezing temperatures in late spring or early autumn.
Habitat & Distribution
Cone production begins in open-grown trees of western red cedar at about 10-20 years of age but peak production occurs after 70-80 years and may continue for several centuries. Good seed crops are produced at intervals of 2-3 years.
In clearcuts and other disturbed areas, seedlings account for most of the western red-cedar regeneration, but seedlings in mature stands may be less abundant than individuals produced by vegetative reproduction from layering, rooting of fallen branches, and branch development on fallen trees. Disturbed mineral soil seems to be a major requirement for regeneration from seed. Unburned soil provides better seedbed than scorched soil, but slash burning may create mineral soil surfaces in cut-over areas. In mature stands of western red cedar, rotten wood in contact with the soil provides an effective seedbed. Partial shade, which lowers evaporation and soil temperature, is beneficial to seedling growth.
Western red cedar is often present in pioneer, seral, and climax stages of forest succession. Vegetative regeneration may be predominant in ecologically stable communities, but wide seed distribution allows it to invade disturbed areas. It is highly shade-tolerant and is well suited for reforesting high brush-risk areas near the coast.
Age determination of western red-cedar is complicated by buttress formation and the associated complex growth patterns, but ring counts of trees from Washington and British Columbia indicate that some trees live at least up to 1460 years.
Foodplant / pathogen
Armillaria mellea s.l. infects and damages Thuja plicata
Foodplant / saprobe
immersed, opening by little lids apothecium of Didymascella thujina is saprobic on dead, attached leaf of Thuja plicata
Remarks: season: 6-8
Foodplant / saprobe
immersed acervulus of Truncatella coelomycetous anamorph of Truncatella hartigii is saprobic on bark of Thuja plicata
Associated Forest Cover
Redcedar is a major component of two forest cover types (11): Western Redcedar (Society of American Foresters Type 228) and Western Redcedar-Western Hemlock (Type 227). It is a minor component of the following types:
210 Interior Douglas-Fir
212 Western Larch
213 Grand Fir
215 Western White Pine
218 Lodgepole Pine
221 Red Alder
222 Black Cottonwood-Willow
223 Sitka Spruce
224 Western Hemlock
225 Western Hemlock-Sitka Spruce
226 Coastal True Fir
229 Pacific Douglas-Fir
230 Douglas-Fir-Western Hemlock
Some associated shrub species are listed in table 1. Several occur in both interior and coastal environments, but Rocky Mountain honeysuckle (Lonicera utahensis) and clematis (Clematis columbiana) are associated with redcedar only in the interior, whereas salmonberry (Rubus spectabilis) and red huckleberry (Vaccinium parvifolium) are found only on the Pacific slope. Pacific rhododendron (Rhododendron macrophyllum) is an abundant associate in coastal California, Oregon, and Washington, but it is rare and confined to isolated locations in south-coastal British Columbia. Salal (Gaultheria shallon) also is an abundant associate. Its range extends farther south than that of redcedar, but the northern limits of salal are nearly the same as the northern limits of western redcedar in coastal Alaska.
Table 1- Shrub species often associated with western redcedar in coastal and interior portions of its native range. Coastal Interior Both Coastal and Interior Oregongrape Mountian alder Western serviceberry (Berberis nervosa) (Alnus tenuifolia) (Amelanchier alnifolia) Stink currant Creeping western barberry Rustyleaf menziesia (Ribes bracteosum) (Berberis repens) (Menziesia ferruginea) Alaska blueberry Common juniper Thimbleberry (Vaccinium alaskaense) (Juniperus communis) (Rubus parviflora) Box blueberry Cascade azalea Oceanspray (Vaccinium ovatum) (Rhododendron albiflorum) (Holodiscus discolor) Red huckleberry Red raspberry Devilsclub (Vaccinium parvifolium) (Rubus idaeus) (Oploponax horridum) Salmonberry Blue huckleberry Pachistima (Rubus spectabilis) (Vaccinium globulare) (Pachistima myrsinites) Pacific rhododendron Rocky Mountain honeysuckle Baldhip rose (Rhododendron macrophyllum) (Lonicera utahensis) (Rosa gymnocarpa) Salal Clematis Common snowberry (Gaultheria shallon) (Clematis columbiana) (Symphoricarpos albus) Ovalleaf huckleberry (Vaccinium ovalifolium) Some associated herb species are listed in table 2. Many are common in both coastal and interior environments. However, slough sedge (Carex obnupta) and Pacific water-parsley (Oenanthe sarmentosa) are limited to moist habitats west of the Cascades, whereas wild sarsaparilla (Aralia nudicaulis) and goldthread (Coptis occidentalis) occur with redcedar only in the interior.
Table 2- Herb species often associated with western redcedar in coastal and interior portions of its native range. Coastal Interior Both Coastal and Interior Threeleaf anemone Goldthread Maidenhair fern (Anemone deltoidea) (Coptis occidentalis) (Adiantum pedatum) Deerfern Everlasting corydalis Ladyfern (Blechnum spicant) (Corydalis sempervirens) (Athyrium filix-femina) Slough sedge Malefern Western swordfern (Carex obnupta) (Dryopteris filix-mas) (Polystichum munitum) Pacific water-parsley Largeleaf avens Mountain woodfern (Oenanthe sarmentosa) (Geum macrophyllum) (Dryopteris austriaca) Oregon oxalis Roundleaf alumroot Prince's-pine (Oxalis oregana) (Heuchera cylindrica) (Chimaphila umbellata) Dwarf blackberry Panicle bluebells Bunchberry (Rubus lasiococcus) (Mertensia paniculata) (Cornus canadensis) Youth-on-age Pine drops Skunkcabbage (Tolmiea menziesii) (Pterospora andromedea) (Lysichitum americanum) White inside-out-flower Green pyrola False Solomon's-seal (Vancouveria hexandra) (Pyrola chlorantha) (Smilacina stellata) Evergreen violet Pacific trillium (Viola sempervirens) (Trillium ovatum) Coastal redcedar plant communities in British Columbia have been classified into 24 associations under 9 alliances in the Thuja-Rubus spectabilis order (35). Communities listed in less detailed coastal classifications include redcedar/swordfern, redcedar/devilsclub/maidenhair fern, redcedar/maidenhair fern-ladyfern, redcedar-western hemlock/devilsclub/ladyfern, redcedar-grand fir/mountain boxwood, redcedar-grand fir/swordfern, redcedar-Douglas-fir/Oregongrape, redcedar-Sitka spruce-red alder/skunkcabbage-slough sedge, and redcedar/skunkcabbage (12,28).
The redcedar/skunkcabbage plant community also occurs in the interior; where redcedar/devilsclub, redcedar/devilsclub/coolwort (Tiarella trifoliata), redcedar/queenscup (Clintonia uniflora), and redcedar/maidenhair fern are found (7,28,42).
Diseases and Parasites
Western redcedar suffers little damage from insects, but it is a host for several economically important insect species (13). One of the most important is the gall midge, Mayetiola thujae, which sometimes seriously damages redcedar seeds in Oregon, Washington, and British Columbia. Newly planted seedlings are occasionally damaged by a weevil (Steremnius carinatus) in British Columbia, and larger trees are killed by a bark beetle (Phloeosinus sequoiae) on poor sites in southeastern Alaska. The western cedar borer (Trachykele blondeli) causes degrade and cull in sawtimber.
More than 200 fungi are found on western redcedar, but it is less susceptible to pathological attacks than are most of its associates. Indeed, redcedar may be a suitable alternative species on coastal Douglas-fir and western hemlock sites where soils are infected with Phellinus weiri, Fomes annosus, or Armillaria spp.(37). Nevertheless, many attacks occur during the long lives of some redcedar trees, and the heartwood extractives that provide decay resistance are eventually detoxified through biodegradation by a series of invading fungi (25). As a result, the volume of accumulated decay in living trees is greater for western redcedar than for any other major conifer in British Columbia (25), and hollow old trees are common in the interior (7).
The major seedling disease, Didymascella thujina, is a leaf blight that infects 2nd- and 3rd-year nursery seedlings. As much as 97 percent of the natural redcedar reproduction may also be killed when this blight reaches epidemic proportions (2). Epidemics are rare in North America, however, and Didymascella is not as damaging here as it is in Europe, where the disease seriously limited production of planting stock until cycloheximide fungicides were developed (3,52).
In North America, the most important fungi attacking redcedar are root, butt, and trunk rots (23). The root and butt rots include Phellinus weiri, Armillaria mellea, and Poria subacida. Poria asiatica and P. albipellucida are the most important trunk rots near the coast; P. asiatica and Phellinus weiri are most important in the interior range of western redcedar (2). These rots are most evident in old stands, where much of the standing volume is often defective and unmerchantable.
Redcedar seedlings and saplings are often severely browsed by deer, elk, or rodents, and browse damage may be the most important stand-establishment problem (6).
Western redcedar is damaged more than Sitka spruce by salt spray. Its foliage is more severely damaged by sulfur dioxide than is the foliage of Douglas-fir, western hemlock, and Sitka spruce and less damaged than the foliage of subalpine fir and grand fir. Redcedar is damaged less than Douglas-fir by airborne fluorides and ozone (30).
Fire Management Considerations
Riparian stringers supporting western redcedar may act as firebreaks
because the moist duff does not readily burn . Old-age western
redcedar stands have heavy fuel loads, but a large proportion of this
material is in the form of deep duff layers and downed, rotting log
material. These stands could support slow moving fires at best; once
ignited, however, such heavy fuel materials could support long-lasting
Fire-killed western redcedar often shows little deterioration even after
5 years. The bark usually remains intact on dead tree for 5 years.
Fire mortality produces no immediate reduction in strength of western
redcedar poles, and some large trees remain salvageable for almost 100
years after being killed by fire .
When slash from decadent western redcedar-western hemlock stands was
burned, a greater proportion of western redcedar than of western hemlock
slash was consumed. This was a result of greater longitudinal and
horizontal fracturing of the western redcedar. When fracturing does not
occur, western hemlock slash is at least as flammable as western
redcedar slash. Fire spreads faster in western redcedar when the slash
from both species is 1 year old. Western redcedar slash does not drop
its foliage. The slash of western redcedar is less flammable when
chipped. One study showed that the fire hazard normally associated with
cutting of western redcedar poles was reduced by skidding entire
pole-size trees to the landing, where the slash was chipped and blown
over the edge .
Slash from western hemlock-western redcedar-Alaska-cedar forests produce
greater nutrient losses to the atmosphere when the slash composition has
a greater proportion of Alaska-cedar and western redcedar. One can
expect smaller nutrient losses when western hemlock makes up the
majority of the slash . For further details on slash burning of
western redcedar refer to the fire case study in the Alaska-cedar Fire
Effects Information System species review.
Broad-scale Impacts of Plant Response to Fire
Hamilton's Research Papers (Hamilton 2006a, Hamilton 2006b) provide
information on prescribed fire and postfire response of plant
community species, including western redcedar, that was not available when
this species review was originally written.
Immediate Effect of Fire
Western redcedar is commonly killed by fire. Because of their large
size, however, old western redcedar trees can often survive if they are
not completely girdled by fire . Shallow roots under the duff layer
are often scorched when the duff layer burns and even surface fires may
kill western redcedar . Fire injury to roots can lead to fungal
infection, chronic stress, and growth losses . The most common
causes of fire mortality are root charring and crown scorching .
Tree without adventitious-bud root crown
Secondary colonizer - off-site seed
Western redcedar fire resistance is low to moderate . Its thin
bark, shallow root system, low dense branching habit, and highly
flammable foliage make it susceptible to fire damage [21,59]. However,
it often survives fire because of it large size . Old western
redcedar trees are commonly fire scarred in northern Idaho .
Western redcedar is more severely damaged by fire than any of its
associates along the coast region but is less susceptible than Engelmann
spruce (Picea engelmannii), western hemlock, and subalpine fir in
interior regions .
The frequency of fire in western redcedar stands tends to be low
[13,73]. In most of the western redcedar forests from southern British
Columbia to northern California moderate to severe wildfires occur at
long intervals between 50 to 350 years . In streamside and seepage
areas dominated by western redcedar the mean fire interval is greater
than 200 years. In western redcedar habitats on lower and middle slopes
the mean fire interval is 50 to 150 years . In the
Selway-Bitterroot Wilderness those stands dominated by western redcedar
had the longest fire regime .
More info for the terms: climax, competition, tree
Obligate Climax Species
Western redcedar is very shade tolerant [8,21,50,51]. It is one of the
most shade tolerant species growing in cedar-hemlock ecosystems of the
northern Rocky Mountains . It is usually considered a climax or
near climax species, but it can be found in all stages of forest
succession. It invades disturbed areas as widely distributed seeds but
regenerates vegetatively in undisturbed areas, tolerating competition in
both . Moisture and soil conditions strongly influence the
successional status of western redcedar. It is climax on wet sites in
the Lake McDonald region of Glacier National Park and on calcium-rich
seepage habitats in British Columbia . In Glacier National Park,
western redcedar enters pioneer communities. The seedlings develop
rapidly in open stands of lodgepole pine (Pinus contorta) and western
larch (Larix occidentalis). It can survive as a late-seral or
coclimax tree on western-hemlock-dominated sites . In Idaho,
western white pine (P. monticola) stands are slowly replaced by a
western hemlock-western redcedar climax .
Seed production and dissemination: Western redcedar reproduces from
seeds more readily in open, disturbed areas, such as clearcuts, than in
undisturbed stands . Seed production normally begins when trees are
20 to 30 years old . However, open-grown trees may produce seed by
age 10 [19,50]. Cones average about three to six seeds, but cones are
often numerous and heavy seed crops are common. Average annual seed
crops vary from 100,000 to 1,000,000 seeds per acre
(247,000-2,470,000/ha) in coastal forests and from 22,000 to 111,000 per
acre (54,000-274,000/ha) in the interior . Pure stands of western
redcedar may yield 60,704,168 seeds per acre (150,000,000/ha). Poor
cone crops are rare . Large seed crops occur every 3 to 4 years
Western redcedar seeds are small, 203,000 to 592,000 seeds per pound
(448,000-1,305/Kg) [8,50]. The seeds are dispersed primarily by wind.
However, the seeds have small wings and are not carried more than 400
feet (122 m) from the parent tree [8,48,50].
Germination: Germination is epigeal. Western redcedar seeds germinate
well without stratification and remain viable for at least 7 years
stored dry (5 to 8 percent moisture) at 0 degrees Fahrenheit (-18 deg C)
. Stratification may improve the germination of some dormant seed
lots. However, in others it may lower the germination capacity .
Haig  reported germination rates of 73 percent, and Schopmeyer 
reported germination rates of 34 to 90 percent.
Mineral soil has been found to be a better seedbed in many environments
than moss or duff, which may dry out rapidly [19,21,50]. Heavily shaded
seedbeds have been associated with the best germination of western
redcedar in British Columbia . Rotten wood that is in contact with
the soil is the preferred seedbed in old western redcedar groves .
Graham  found that germination was best on burned surfaces.
Seedling development: Western redcedar seedling survival is low [8,50].
Drought and high soil temperatures damage seedlings grown in full
sunlight [8,40]. Fungi, birds, insects, and smothering by fallen leaves
of deciduous shrubs are some other causes for the high mortality of
western redcedar seedlings [8,19]. Seedlings grow best in partial
shade, although they may fail on heavily shaded sites due to poor root
penetration . Seedlings show high resistance to root flooding 
and respond well to removal of competition . In one study, removal
of shrubs resulted in an increase in height growth of western redcedar
compared to unreleased trees .
Of all conifers in the northern Rocky Mountains, western redcedar and
western hemlock seedlings grow the slowest. Annual height growth of
western redcedar seedlings is highly variable, from less than 0.39
inches (1 cm) in dense stands to over 7.5 inches (19 cm) in thinned
Vegetative reproduction: Communities with closed canopies favor
vegetative reproduction over sexual reproduction . Western redcedar
generally relies on vegetative reproduction in climax old-growth stands
with high soil moisture throughout the growing season [21,27]. The
frequent absence of adequate moisture in the upper soil layers of
well-drained sites often is responsible for western redcedar's reduced
ability to vegetatively reproduce on upland sites . Three natural
types of vegetative reproduction occur: (1) layering, (2) rooting of
fallen, living branches that have been torn off by wind or snow and have
fallen on wet soil; and (3) rooting along the trunks of fallen, living
Growth Form (according to Raunkiær Life-form classification)
Plant Response to Fire
seedbeds via off-site wind dispersed seeds [22,26]. Although unburned
soil benefits western redcedar regeneration more than soil that has been
scorched, slash burning favors western redcedar by creating more mineral
soil surfaces in cutover areas .
Reaction to Competition
Western redcedar is best managed on moist sites characterized by the presence of ladyfern, queenscup, mountain woodfern, oakfern (Gymnocarpium dryopteris), or thimbleberry. On poorly drained sites of lower quality, fertilizing with nitrogen appears to benefit growth (37). Urea seems to be a better source of that nitrogen than ammonium nitrate (54). Redcedar can be grown in stands of mixed species where uneven-aged management is practiced or when redcedar poles are to be produced under normal even-aged management regimes. But pure stands are more suitable for the long rotations needed to produce large sawtimber, shingles, and shakes.
Where western redcedar is managed in mixed-species or uneven-aged stands, its excellent shade tolerance and long life should be considered. Redcedar is usually overtopped by Douglas-fir, grand fir, western hemlock, and western white pine. It tolerates understory conditions in mixed-species stands but often grows slowly there. In uneven-aged stands, western redcedar can maintain acceptable growth rates over long periods, but it should not be given excessive crown space. Thinning from above may release the redcedars in mixed-species stands; thinning from below is preferable in uneven-aged stands of western redcedar. In the northern Rocky Mountains, growth response to release is best on large, young redcedars with green-yellow foliage growing on northerly aspects (17). Redcedars probably should not be released when overtopped, however, because much of the increased growth after their release often occurs in large branches and a spreading crown rather than stem wood (37).
Most western redcedars are harvested by clearcutting the mixed-species stands in which they grow. Because of steep terrain, decay, and breakage, redcedar harvesting costs are high and lumber recovery is low (55). Redcedars should not be left as scattered seed trees, however; even those along clearcut margins may be lost to windthrow or exposure. Effects of slash-burning vary with site conditions, but low-impact spring burns tend to benefit the mycorrhizal colonization of seedlings (6).
Western redcedar roots usually are deeper than the roots of western hemlock but shallower than the roots of western larch, western white pine, grand fir, and Douglas-fir (30). The soils on which these species usually grow may be responsible, however, because western redcedar, western hemlock, and Douglas-fir trees of similar size growing on similar soils have roots that penetrate to similar depths and extend over similar areas (10). Shallow root systems are most frequent where soil bulk density is high. Redcedar roots cannot grow in dense soils penetrated by the roots of Douglas-fir, red alder, lodgepole pine, and Pacific silver fir (30). Redcedar root systems also tend to be shallower and less extensive on wet sites than they are on deep, moderately dry soils.
Where a thick duff layer is present, many redcedar roots lie in the duff rather than in the underlying soil. Root grafting is common (9). Western redcedar mycorrhizae are of the vesicular-arbuscular type, and redcedar seedlings are more responsive to mycorrhizal inoculation than are the seedlings of redwood (Sequoia sempervirens), incense-cedar (Libocedrus decurrens), and giant sequoia (Sequoiadendron giganteum) (27).
Life History and Behavior
More info for the term: phenology
The reproductive cycle of western redcedar occurs over approximately 16
months. Phenology varies between coastal and interior regions. For
trees in the middle of the coastal distribution on Vancouver Island,
pollen and seed cones develop in early June. Pollen forms in late
February or early March of the second season. Pollination occurs within
1 to 2 weeks usually in March but may begin as early as mid-February in
mild coastal areas or as late as early April at higher elevations.
Pollination in March is most common . Fertilization occurs in late
May. Cones mature in October. West of the Cascade Range, cone maturity
is usually reached in 5 months, but in northern Idaho it takes 3 months.
Major seedfall occurs during October and November in both the interior
and coast range . Dry warm weather can cause earlier seed release.
Some seeds may be retained in the cones and gradually shed throughout
the winter . Where moisture and temperature conditions are
favorable, germination can occur in the autumn, winter, or spring .
Along the coast region, seeds generally germinate in either fall or
Redcedar clones are easily propagated by the rooting of stem cuttings. Although untreated cuttings will root, a 1-minute dip in a 3,000 ppm solution or a 4-hour soak in a 200 to 400 ppm solution of indolebutyric acid improves rooting speed, the number of cuttings rooted, and the total length of roots per cutting. Ramets for seed orchards can be produced by treating cuttings with indolebutyric acid, then rooting them in a 1-to-1 mixture of peat and perlite (8). Young fragmented stems can be induced to bud after being soaked in a cytokinin solution, and the resulting buds can be rooted on a culture medium that contains napthalineacetic acid and kinetin (33).
Throughout the range of western redcedar, disturbed mineral soil seedbeds seem to be a major requirement for regeneration from seed (41). Although unburned soil benefits redcedar more than soil that has been scorched, slash burning favors redcedar by creating more mineral soil surfaces in cutover areas. Rotten wood that is in contact with the soil is the preferred seedbed in old redcedar groves (41). Partial shade is beneficial because drought and high soil temperature damage seedlings in full sunlight, and poor root penetration causes damage from drought in full shade (48).
Direct seeding in the autumn is successful where soil moisture is available, but large quantities of seed may be required to obtain adequate stocking. In the nursery, spring sowing is best; half-shaded seedbeds are recommended (47). Pelleting the seeds makes them more compatible with automated nursery sowing machinery (8). Containerized nursery seedlings can be produced in 7 months. They survive as well or better than bare-root stock when planted in coastal Oregon, Washington, and British Columbia, but 2-year-old bare-root stock tends to be most cost effective in the coastal range (6). When bare-root stock is planted, recently lifted dormant seedlings with low shoot/root ratios should be used and cold storage avoided whenever possible. Containerized stock planted in the spring appears to perform better than bare-root stock in the interior (18). Natural regeneration is important in the northern Rocky Mountains, where it is most frequently successful on westerly and northerly aspects in western redcedar habitat types (18).
Western redcedar seedlings are less tolerant of high soil temperature and of frost than are the seedlings of Engelmann spruce, grand fir, and Douglas-fir. The exposed upper foliage of young redcedars often sunburns severely (31). Roots of seedlings grow more slowly than the roots of Douglas-fir and incense-cedar, but they outgrow the roots of seedling western hemlock and Sitka spruce. Shoots have a longer growth period than any associated conifer. Non-rigid leaders are produced, and neither lateral nor terminal shoots form dormant buds. Lateral shoot growth is vigorous, amounting to at least 80 percent of terminal shoot growth in young redcedars (31). Seedlings account for most of the western redcedar regeneration in clearcuts and other disturbed areas. On good coastal sites, they grow as tall or taller than Douglas-fir, western hemlock, and Sitka. spruce seedlings during the first 5 years (6,51). The redcedars are subsequently overtaken by Douglas-fir (by age 10) and western hemlock (by age 15).
Seed Production and Dissemination
Seeds are small- 448,000 to 1,305,000/kg (203,000 to 592,000/1b) (47). They fall faster and do not fly as far as the seeds of western hemlock, Sitka spruce, and Douglas-fir, but dissemination is adequate within 100 m (330 ft) of a seed source (4,30). The seeds usually germinate well without stratification, and they retain their initial viability for at least 7 years when stored dry (5 to 8 percent moisture) at -18° C (0° F) (8). Germination is epigeal.
Flowering and Fruiting
Growth and Yield
Pure, even-aged stands can attain volumes comparable to pure Douglas-fir stands by age 50 on high-quality upland sites in western Washington (37), Plantations should be dense (about 2,470 trees per hectare or 1,000/acre), and intermediate crown classes should be removed in a light thinning to reduce side shade at about age 25 (22,36). Stands of 370 to 430 crop trees/ha (150 to 175 crop trees/acre) at time of harvest may allow maximum diameter growth without causing poor form (36). Maintaining a nearly closed canopy at all times will benefit form because open-grown redcedars tend to develop excessively large limbs and multiple tops. Faster growing trees of acceptable quality can be grown at wide spacings if their lower holes are pruned (50), but percentages of latewood decrease significantly (49).
Volumes of 379 to 825 m³/ha (5,418 to 11,782 ft³/acre) were measured in 40- to 60-year-old pure second-growth stands on moist sites in western Washington (36). A yield model on medium sites in British Columbia indicates yields of 70 m³/ha (1,000 ft³/acre) at age 40, 350 m³/ha (5,000 ft³/acre) at age 115, and 595 m³/ha (8,500 ft³/acre) at age 270; maximum current annual increment occurs at 82 years and maximum mean annual increment at 130 years (34).
In Great Britain, the cumulative volume produced by normal western redcedar stands on poor sites is 50 m³/ha (714 ft³/acre) at age 20 and 953 m³/ha (13,620 ft³/acre) at age 80. On good sites, cumulative volume produced is 232 m³/ha (3,315 ft³/acre) at age 20 and 1839 m³/ha (26,268 ft³/acre) at age 80. The average age of maximum mean annual increment is 72 on poor sites and 58 on good sites in these British stands (22). At ages 20 and 50, cumulative volume production is lower for western redcedar than for Douglas-fir and Sitka. spruce in Great Britain, but by age 80 the redcedar volume production is higher than that of Douglas-fir and spruce (45).
Growth is often much slower. Suppressed redcedar trees that are 200 years old but only 7.6 cm. (3 in) in d.b.h. and 7.6 m (25 ft) tall are not unusual. Survival for such long periods of suppression may be due to the ability of the species to produce new root growth in full shade. It may also be a result of frequent root grafting. Dominant trees often support growth of the root systems and lower boles of suppressed trees (9).
Molecular Biology and Genetics
Races Several horticultural varieties of western redcedar are grown in North America. They include atrovirens, fastigiata, and pendula. Haploid and triploid varieties have been studied in Germany (31).
Hybrids Thuja plicata x Thuja standishii hybrids are resistant to the leaf blight caused by Didymascella thujina (52).
Barcode data: Thuja plicata
Statistics of barcoding coverage: Thuja plicata
Public Records: 5
Specimens with Barcodes: 13
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Despite extensive logging, the extensive range and abundance of Thuja plicata makes it ineligible for any threatened category and it is therefore assessed as Least Concern.
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Common species of northwest North America, with thousands of occurrences.
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.
Insects and disease: Western redcedar is a host for several
economically important insect species. One of the most important is the
gall midge (Mayetiola thujae), which sometimes seriously damages western
redcedar seeds in Oregon, Washington, and British Columbia .
Seedlings are occasionally damaged by weevils (Steremnius carenatus) in
British Columbia, and large trees are killed by bark beetles
(Phloeosinus sequoiae) on poor sites in southeastern Alaska. The
western redcedar borer (Trachykele blondeli) causes degradation
resulting in cull of sawtimber .
More than 200 fungi are found on western redcedar. A leaf blight
(Didymascella thujina) infects second- and third-year nursery seedlings.
As much as 97 percent of the natural western redcedar regeneration may
be killed when this blight reaches epidemic proportions. The most
important fungi attacking western redcedar are root butt and trunk rots.
Poria asiatiaa and P. albipellucida are the most important trunk rots
near the coast; P. asiatioa and Phellinus weiri are the most important
in the interior range. Rots are most evident in old stands .
Animal damage: Seedlings and saplings are often severely browsed by
deer, elk, and rodents. Browse damage may be one of the most important
stand establishment problems . Grazing by cattle in burned stands
in the western redcedar/queencup beadlily (Clintonia uniflora) habitat
type in southwestern Montana retards establishment of western redcedar
Other damaging agents: Western redcedar is often windthrown in wet
environments, but it is windfirm on dry sites [50,51]. Western redcedar
is damaged by salt spray . It is also sensitive to atmospheric
pollution. Clay dust from a brick works in British Columbia produced a
columnar form in nearby western redcedars .
Silvicultural considerations: Care must be exercised when logging sites
dominated by western redcedar due to the high water table. Bottomland
sites should not be disturbed other than to salvage high-value trees or
to remove high-risk trees. If harvested some dead and down logs should
be left to serve as a seedbed for western redcedar and western hemlock
regeneration. Extensive disturbance of these sites could cause
irreparable damage .
Western redcedar should be grown in pure stands when saw-timber,
shingles, or shakes are the desired products. Even-aged mixtures of
western redcedar and other conifers will be harvested either too early
for the western redcedar sawtimber or too late for the other conifers
when mixed-species, even-aged stands are clearcut. Western redcedar can
be grown in mixed stands when poles are to be produced under even-aged
management regimes. A nearly closed canopy should be maintained at all
times. Open-grown western redcedar tend to develop poor form, excessive
limbs, and multiple tops . Western redcedar is perhaps the most
valuable species for which uneven-aged systems are applicable in the
highly productive western redcedar and western hemlock habitat types of
the Inland West .
Response to release: Because western redcedar is shade tolerant, it
should be treated to minimize shock from release through slow or timely
thinning treatments. Western redcedar's ability to respond to release
varies with tree, stand, and site conditions. An 80-year-old western
redcedar stand, with the overstory removed and thinned, responded with
increased growth rates up to 5 years after treatment. However, 5 to 10
years after release, growth rates slowed, and root diseases became
apparent . Releasing western redcedar saplings slowly over a 17
year period had good results. The saplings responded favorably to
release with increased growth rates and a gradual increase in vigor.
Thinning western redcedar stands should occur prior to age 30. Spacing
of 1 foot by 1 foot (0.3 by 0.3 m) is appropriate for most young stands.
This density provides good tree and stand development and retains the
options for future intermediate treatments [25,26].
Cultivars, improved and selected materials (and area of origin)
These plant materials are readily available from commercial sources. Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”
In mixed-species and uneven-aged stands, western red cedars tolerate shady understory conditions and can maintain slow but acceptable growth rates over long periods. In timber harvest of these mixed-species stands, most of these trees are taken by clearcutting. Because of steep terrain, decay, and breakage, harvesting costs are high and lumber recovery is low. Because of its high susceptibility to windthrow in wet environments and in the moist sites where growth and yield are highest, western red cedars should not be left as scattered seed trees. Even those along clearcut margins may be lost to wind throw or exposure.
Severe browse damage to western red-cedar seedlings and saplings by deer, elk, and rodents may be the most important problem in the establishment of young stands. In near-coastal sites, western red-cedar is more severely damaged by fire than any of its associates.
Relevance to Humans and Ecosystems
Other uses and values
Perfumes, insecticides, medicinal preparations, veterinary soaps, shoe
polishes, and deodorants are made from western redcedar leaf oil.
Western redcedar extractives and residues are used in lead refining,
boiler-water additives, and glue extenders . Western redcedar was
an extremely valuable tree to the Indians of the Northwest Coast,
providing materials for their shelters, clothing, dugout canoes, and
fishing nets [8,76]. Northwest Coast Indians shredded the inner layer
of bark so finely that it could be used for diapers and cradle padding
Western redcedar's drooping branches, thin fibrous bark, and flat sprays
of scalelike leaves make it an attractive ornamental. When properly
trimmed western redcedar is an excellent hedge [8,41].
Value for rehabilitation of disturbed sites
range. The erosion-control potential and long-term revegetation
potential of western redcedar have been rated as medium . Western
redcedar may be the species of choice for reforesting high, brush-risk
areas near the coast . It is suitable for planting on slightly dry
to wet nutrient-poor to nutrient-rich sites [commonly with Douglas-fir,
Sitka spruce (Picea sitchensis), Alaska-cedar (Chamaecyparis
nootkatensis), or western hemlock]. Western redcedar does best when
planted in mineral soils on upland sites and in well-decomposed organic
material on lowland sites . Containerized western redcedar appears
to perform somewhat better than bareroot stock . Direct seeding is
practical and effective where a mineral soil seedbed is available.
Methods for collecting, storing, and planting western redcedar seeds and
seedlings have been detailed [50,51,69].
Importance to Livestock and Wildlife
Black-tailed deer browse western redcedar seedlings and saplings all
year long in British Columbia, and Roosevelt elk feed on them during the
fall, winter, and spring. Western redcedar constitutes one of the most
important conifer foods of black-tailed deer in the Coastal forest
region of southern Vancouver Island . Western redcedar was more
severely browsed than Douglas-fir (Pseudotsuga menziesii), western
hemlock, or Pacific silver fir (Abies amabilis) on the Olympic
Peninsula. Western redcedar is a major winter food for big game in the
northern Rocky Mountains . An analysis of 69 stomach samples
collected from elk harvested along the Lochsa and lower Selway rivers
between January 1 and April 1 from 1960 through 1970 showed that western
redcedar leaves made up 5 percent of the total winter diet by weight
. In western Washington, black bears remove western redcedar bark
and feed on the exposed sapwood .
Cattle browse western redcedar in preference to Douglas-fir in
northwestern Oregon, and sheep damaged western redcedar reproduction
more than that of other trees in northern Idaho . Seeds of this
conifer were only occasionally taken by field mice in caged tests .
Old-growth stands of western redcedar provide hiding and thermal cover
for several wildlife species. Bears, raccoons, skunks, and other
animals use cavities in western redcedar for dens . In the southern
Selkirk Mountains of northern Idaho, northeastern Washington, and
adjacent British Columbia, grizzly bears have been known to use heavily
timbered western redcedar and western hemlock forests . Western
redcedar is used as nest trees by cavity nesting bird species such as
yellow-bellied sapsuckers, hairy woodpeckers, tree swallows, chestnut
backed chickadees, and Vaux's swifts [45,49].
Wood Products Value
Western redcedar is an important commercial species throughout much of
its natural range . In the Rocky Mountains, western redcedar
occupies some of the most productive sites, often producing stands with
high volume . The wood is low in strength and soft but is very
resistant to decay, making it best suited for use as exposed building
material such as shingles, shakes, and exterior siding [57,69].
Hand-split western redcedar shakes sell for several times the price of
asphalt shingles but will last 100 years on a roof . The wood is
fine and straight grained, which makes it suitable for interior
finishing . Western redcedar wood is also used for utility poles,
fence posts, light construction pulp, clothes closets and chests, boats,
canoes, fish trap floats, caskets, crates, and boxes [50,80].
nitrogen are nearly always present in western redcedar foliage.
Phosphorous concentrations are usually low .
Industry: The wood of western red cedar is primarily used in roofing for shingles and shakes, because of its attractive appearance, durability, lightness, and superior insulation qualities. It is also used in exterior finishings, utility poles, fence posts, piling, paper pulp, and various types of containers. The species is managed for timber in Europe and New Zealand. Cedar leaf oil is often the basis for production of perfumes, insecticides, medicinal preparations, veterinary soaps, shoe polishes, and deodorants.
Wildlife: The leaves of western red cedar are a major winter food for big game in the northern Rocky Mountains, and deer browse it all year along the coast. Many cultivars are grown for ornament, including those used for hedges. It is the provincial tree of British Columbia.
Ethnobotanic: Western red cedar has been called “the cornerstone of northwest coast Indian culture” and the large-scale use of its wood and bark delineates the cultural boundary of the northwest coast peoples within its range. Wood served for house planks, house posts, roof boards, various kinds of boxes, and canoes. It is easy to split and was often used for bentwood boxes. Bark was made into skirts, capes, and complete dresses for women, and roots and limbs were used for baskets and rope. The inner bark was used for slow matches to carry the fire from camp to camp, and also as mats, and baskets. Various medicines were derived from the tree.
Thuja plicata, commonly called western or Pacific redcedar, giant or western arborvitae, giant cedar, or shinglewood, is a species of Thuja, an evergreen coniferous tree in the cypress family Cupressaceae native to western North America. The provincial tree of British Columbia, it has extensive applications for Native Americans of the Pacific Northwest.
Thuja plicata is among the most widespread trees in the Pacific Northwest. It is associated with Douglas-fir and western hemlock in most places where it grows. It is found at the elevation range of sea level to a maximum of 2,290 m (7,510 ft) above sea level at Crater Lake in Oregon. In addition to growing in lush forests and mountainsides, western redcedar is also a riparian tree, growing in many forested swamps and streambanks in its range. The tree is shade-tolerant and able to reproduce under dense shade.
It has been introduced to other temperate zones, including western Europe, Australia (at least as far north as Sydney), New Zealand, the eastern United States (at least as far north as Central New York), and higher elevations of Hawaii.
Thuja plicata is a large to very large tree, ranging up to 65 to 70 m (213 to 230 ft) tall and 3 to 4 m (9.8 to 13.1 ft) in trunk diameter, exceptionally even larger. Trees growing in the open may have a crown that reaches the ground, whereas trees densely spaced together will exhibit a crown only at the top, where light can reach the leaves. It is long-lived; some individuals can live well over a thousand years, with the oldest verified being 1460 years.
The foliage forms flat sprays with scale-like leaves in opposite pairs, with successive pairs at 90 degrees to each other. The foliage sprays are green above and green marked with whitish stomatal bands below; they are strongly aromatic, with a scent reminiscent of pineapple when crushed. The individual leaves are 1 to 4 mm (0.039 to 0.157 in) long and 1 to 2 mm (0.039 to 0.079 in) broad on most foliage sprays, but up to 12 mm (0.47 in) long on strong-growing lead shoots.
The cones are slender, 10 to 18 mm (0.39 to 0.71 in) long, and 4 to 5 mm (0.16 to 0.20 in) broad, with 8 to 12 (rarely 14) thin, overlapping scales. They are green to yellow-green, ripening brown in fall about six months after pollination, and open at maturity to shed the seeds. The seeds are 4 to 5 mm long and 1 mm (0.039 in) broad, with a narrow papery wing down each side. The pollen cones are 3 to 4 mm (0.12 to 0.16 in) long, red or purple at first, and shed yellow pollen in spring.
Taxonomy and name
Thuja plicata is one of two Thuja species native to North America, the other being Thuja occidentalis. The species name plicata derives from the Latin word plicare, meaning "folded in plaits" or "braided," a reference to the pattern of its small leaves.
Most authorities, both in Canada and the United States cite the English name in two words as western redcedar, or occasionally hyphenated as western red-cedar, to indicate is not a cedar (Cedrus), but it is also cited as western red cedar in some popular works. In the American horticultural trade, it is also known as the giant arborvitae, by comparison with arborvitae for its close relative Thuja occidentalis. Other names include giant redcedar, Pacific redcedar, shinglewood, British Columbia cedar, canoe cedar, and red cedar. Arborvitae comes from the Latin for "tree of life"; coincidentally, native Americans of the West coast also address the species as "long life maker".
The "Quinault Lake Redcedar" is the largest known western redcedar in the world, with a wood volume of 17,650 cubic feet (500 m3). Located near the northwest shore of Lake Quinault north of Aberdeen, Washington, about 34 km (21 mi) from the Pacific Ocean, it is one-third the volume of the largest known tree, a giant sequoia named "General Sherman". The Quinault Lake Redcedar is 174 feet (53 m) tall with a diameter of 19.5 feet (5.9 m) at breast height. The second largest is the Cheewhat Lake Cedar, in Pacific Rim National Park Reserve on Vancouver Island, at 15,870 cubic feet (449 m3). The tallest known individual is the Willaby Creek Tree south of Lake Quinault, 195 feet (59 m) in height. The fifth known largest was the Kalaloch Cedar in the Olympic National Park, at 12,370 cubic feet (350 m3), until it was destroyed by storm in March 2014.
A redcedar over 71 m (233 ft) tall, 4.5 m (15 ft) in diameter, and over 700 years old stood in Cathedral Grove on Vancouver Island, British Columbia, before it was set on fire and destroyed by vandals in 1972. That tree now lies in "Giant's Grave", a self dug grave created by the force of its own impact.
|This section needs additional citations for verification. (February 2012)|
The soft red-brown timber has a tight, straight grain and few knots. It is valued for its distinct appearance, aroma, and its high natural resistance to decay, being extensively used for outdoor construction in the form of posts, decking, shingles, and siding. It is commonly used for the framing and longwood in lightweight sail boats and kayaks. In larger boats it is often used in sandwich construction between two layers of epoxy resin and/or fibreglass or similar products. Due to its light weight—390 to 400 kg/m3 (24 to 25 lb/cu ft) dried—it is about 30% lighter than common boat building woods, such as mahogany. For its weight it is quite strong but can be brittle. It glues well with epoxy resin or resorcinol adhesive.
It is also used to line closets and chests, for its pungent aromatic oils are believed to discourage moth and carpet beetle larvae, which can damage cloth by eating wool and similar fibres. This is more effective in a properly constructed redcedar chest (sometimes made entirely of redcedar), since the oils are confined by shellac and leather seals. A well-sealed redcedar chest will retain its pungent odour for many decades, sometimes for over a century. Its light weight, strength and dark warm sound make it a popular choice for guitar soundboards.
Like its relative Thuja occidentalis and many other conifer species, Thuja plicata is grown as an ornamental tree, and for screens and hedges, throughout the world in gardens and parks. A wide variety of forms, sizes, and colours is available.
- Other uses
Thujaplicin, a chemical substance, is found in mature trees and serves as a natural fungicide, thereby preventing the wood from rotting. This effect lasts around a century even after the tree is felled. However, thujaplicin is only found in older trees. Saplings that do not produce the chemical often rot at an early stage, causing some trees to grow with a somewhat hollow, rotten trunk.
It is also widely used throughout Europe and America for making beehive frames.
Role in indigenous societies
Western redcedar has an extensive history of use by the indigenous peoples of the Pacific Northwest Coast, from Oregon to southeast Alaska. Some northwest coast tribes refer to themselves as "people of the redcedar" because of their extensive dependence on the tree for basic materials. The wood has been used for constructing housing and totem poles, and crafted into many objects, including masks, utensils, boxes, boards, instruments, canoes, vessels, houses, and ceremonial objects. Roots and bark were used for baskets, bowls, ropes, clothing, blankets, and rings.
A huge number of archeological finds point to the continuous use of redcedar wood in native societies. Woodworking tools dating between 8000 and 5000 years ago, such as carved antlers, were discovered in shell middens at the Glenrose site, near Vancouver, British Columbia. In Yuquot, on the west coast of Vancouver Island, tools dating 4000 to 3000 years old have been found. The Musqueam site, also near Vancouver, yielded bark baskets woven in five different styles, along with ropes and ships dated to 3000 years ago. At Pitt River, adzes and baskets were dated around 2900 years aol. Wooden artifacts 1000 years old were unearthed on the east coast of Vancouver Island.
Red Cedar was used extensively wherever it was found along the northwest coast (British Columbia, Washington state, Parts of Alaska). Evidence of this use is found in CMTs (Culturally Modified Trees) that are found throughout the coast. When First Nations people removed the bark from cedars, it left a scar - which is considered a CMT. Other types of harvest (for planks, tinder, and other uses) leave different types of evidence of cultural modification.
A legend amongst the Coast Salish peoples describes the origins of the western redcedar. In this legend, there was a generous man who gave the people whatever they needed. When the Great Spirit saw this, he declared that when the generous man died, a great redcedar tree will grow where he is buried, and that the cedar will be useful to all the people, providing its roots for baskets, bark for clothing, and wood for shelter.
The wood was worked primarily with the adze, which was preferred over all other tools, even ones introduced by European settlers. Alexander Walker, an ensign on the fur trade ship Captain Cook, reported that the indigenous peoples used an elbow adze, which they valued over new tools brought by the Europeans, such as the saw or the axe, going so far as to modify traded tools back into an adze. Tools were generally made from stone, bone, obsidian, or a harder wood such as hemlock. A variety of hand mauls, wedges, chisels, and knives were used. Excavations done at Ozette, Washington turned up iron tools nearly 800 years old, far before European contact. When James Cook passed the area, he observed that almost all tools were made of iron. There has been speculation on the origin of these iron tools. Some theories include shipwrecks from East Asia or possible contact with iron-using cultures from Siberia, as hinted in the more advanced woodworking found in northern tribes such as the Tlingit.
Harvesting redcedars required some ceremony and included propitiation of the tree's spirits as well as those of the surrounding trees. In particular, many people specifically requested the tree and its brethren not to fall or drop heavy branches on the harvester, a situation which is mentioned in a number of different stories of people who were not sufficiently careful. Some professional loggers of Native American descent have mentioned that they offer quiet or silent propitiations to trees which they fell, following in this tradition.
Felling of large trees such as redcedar before the introduction of steel tools was a complex and time-consuming art. Typically the bark was removed around the base of the tree above the buttresses. Then some amount of cutting and splitting with stone adzes and mauls would be done, creating a wide triangular cut. The area above and below the cut would be covered with a mixture of wet moss and clay as a firebreak. Then the cut would be packed with tinder and small kindling and slowly burned. The process of cutting and burning would alternate until the tree was mostly penetrated through, and then careful tending of the fire would fell the tree in the best direction for handling. This process could take many days. Constant rotation of workers was involved to keep the fires burning through night and day, often in a remote and forbidding location.
Once the tree was felled, the work had only just begun, as it then had to be stripped and dragged down to shore. If the tree was to become canoes, then it would often be divided into sections and worked into rough canoe shapes before transport. If it were to be used for a totem pole or building materials, it would be towed in the round to the village. Many trees are still felled in this traditional manner for use as totem poles and canoes, particularly by artists who feel that using modern tools is detrimental to the traditional spirit of the art. Non-traditionalists simply buy redcedar logs or lumber at mills or lumber yards, a practice that is commonly followed by most working in smaller sizes such as for masks and staves.
Because felling required such an extraordinary amount of work, if only planks for housing were needed, these would be split from the living tree. The bark was stripped and saved, and two cuts were made at the ends of the planking. Then wedges would be pounded in along the sides and the planks slowly split off the side of the tree. Trees which have been so harvested are still visible in some places in the rainforest, with obvious chunks taken off of their sides. Such trees usually continue to grow perfectly well, since redcedar wood is resistant to decay. Planks are straightened by a variety of methods, including weighing them down with stones, lashing them together with rope, or forcing them between a line of stakes.
Redcedar wood is used to make huge monoxyla canoes in which the men went out to high sea to harpoon whales and conduct trade. One of those canoes, a 38-foot (12 m) craft dug out about a century ago, was bought in 1901 by Captain John Voss, an adventurer. He gave her the name of Tilikum ("Friend" in Chinook jargon), rigged her, and led her in a hectic three-year voyage from British Columbia to London.
Redcedar branches are very flexible and have good tensile strength. They were stripped and used as strong cords for fishing line, rope cores, twine, and other purposes where bark cord was not strong enough or might fray. Both the branches and bark rope have been replaced by modern fiber and nylon cordage among the aboriginal northwest coast peoples, though the bark is still in use for the other purposes mentioned above.
At the right time of year, the bark is easily removed from live trees in long strips. It is harvested for use in making mats, rope and cordage, basketry, rain hats, clothing, and other soft goods. The harvesting of bark must be done with care because, if the tree is completely stripped, it will die. To prevent this, the harvester usually only harvests from trees which have not been stripped before. After harvesting the tree is not used for bark again, although it may later be felled for wood. Stripping bark is usually started with a series of cuts at the base of the tree above any buttresses, after which the bark is peeled upwards. To remove bark high up, a pair of platforms strung on rope around the tree are used and the harvester climbs by alternating between them for support. Since redcedars lose their lower branches as all tall trees do in the rainforest, the harvester may climb 10 m (33 ft) or more into the tree by this method. The harvested bark is folded and carried in backpacks. It can be stored for quite some time as mold does not grow on it, and is moistened before unfolding and working. It is then split lengthwise into the required width and woven or twisted into shape. Bark harvesting was mostly done by women, despite the danger of climbing 10 meters in the air, because they were the primary makers of bark goods.
Today bark rope making is a lost art in many communities, although it is still practiced for decoration or art in a few places. Other uses of bark are still common for artistic or practical purposes. In recent years there has been a revival of cedar weaving in some communities, and along with it, new forms of cedar bark products. For example, in some recent weddings cedar roses are used to decorate the tables.
Western red cedar is export-restricted in the United States under the Export Administration Regulations.
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Thuja plicata is an important timber tree. Its soft but extremely durable wood is valued for home construction, production of shakes and shingles, and many other uses. Native Americans of the Northwest Coast used it to build lodges, totem poles, and seagoing canoes. Many cultivars are grown for ornament, and the species is managed for timber in Europe and New Zealand.
Western redcedar ( Thuja plicata ) is the provincial tree of British Columbia.
Names and Taxonomy
plicata Donn ex D. Don [8,50,51,57]. It is a member of the Cypress
family (Cupressaceae). Western redcedar hybridizes with Thuja
standishii. Hybrids are resistant to the leaf blight caused by
Didymascella thujina . There are no recognized subspecies,
varieties, or forms.