Index of Species Information

SPECIES:  Thuja plicata

Introductory

SPECIES: Thuja plicata
AUTHORSHIP AND CITATION : Tesky, Julie L. 1992. Thuja plicata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].
ABBREVIATION : THUPLI SYNONYMS : NO-ENTRY SCS PLANT CODE : THPL COMMON NAMES : western redcedar western red-cedar Pacific redcedar giant redcedar arborvitae canoe-cedar shinglewood giant arborvitae TAXONOMY : The currently accepted scientific name for western redcedar is Thuja 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 [50]. There are no recognized subspecies, varieties, or forms. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


DISTRIBUTION AND OCCURRENCE

SPECIES: Thuja plicata
GENERAL DISTRIBUTION : Western redcedar occurs along the Pacific Coast from the southern part 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 [54].  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 Montana [50,54,57]. ECOSYSTEMS :    FRES20  Douglas-fir    FRES21  Ponderosa pine    FRES22  Western white pine    FRES23  Fir - spruce    FRES24  Hemlock - Sitka spruce    FRES25  Larch    FRES26  Lodgepole pine    FRES27  Redwood    FRES28  Western hardwoods STATES :      AK  CA  HI  ID  MT  OR  WA  AB  BC BLM PHYSIOGRAPHIC REGIONS :     1  Northern Pacific Border     2  Cascade Mountains     5  Columbia Plateau     8  Northern 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    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 SAF COVER 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 - hemlock    227  Western redcedar - western hemlock    228  Western redcedar    229  Pacific Douglas-fir    230  Douglas-fir - western hemlock    231  Port-Orford-cedar    232  Redwood SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : 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 [60] 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 [35].  Daubenmire and Daubenmire [16] 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 [3]. Preliminary plant associations of the southern Oregon Cascade Mountain   Province [11]. Classification and management of riparian and wetland sites in   northwestern Montana [13].  Forest habitat types of northern Idaho: a second approximation [15]. Forest Vegetation of eastern Washington and northern Idaho [16]. Fire ecology of Lolo National Forest habitat types [17]. Preliminary forest plant association management guide. Ketchikan area,   Tongass National Forest [18]. Fire ecology of western Montana forest habitat types [21]. A guide to the interior cedar-hemlock zone, northwestern transitional   subzone (ICHg), in the Prince Rupert Forest Region, British Columbia   [33]. Riparian dominance types of Montana [35]. Classification and management of riparian sites in southwest Montana   [36]. Soil classification as an aid to identifying forest habitat types in   northern Idaho [54]. Forest habitat types of Montana [60]. Reference material Daubenmire habitat types [77]. Preliminary forest plant associations of the Stikine area, Tongass   National Forest [78]. A study of the Vegetation of southeastern Washington and adjacent Idaho   [81].

MANAGEMENT CONSIDERATIONS

SPECIES: Thuja plicata
WOOD PRODUCTS VALUE : Western redcedar is an important commercial species throughout much of its natural range [80].  In the Rocky Mountains, western redcedar occupies some of the most productive sites, often producing stands with high volume [26].  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 [8].  The wood is fine and straight grained, which makes it suitable for interior finishing [57].  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]. 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 [51].  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 [51].  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 [72].  In western Washington, black bears remove western redcedar bark and feed on the exposed sapwood [50]. 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 [51].  Seeds of this conifer were only occasionally taken by field mice in caged tests [52]. 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 [8].  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 [44].  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]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : Relatively high concentrations of calcium and low concentrations of nitrogen are nearly always present in western redcedar foliage. Phosphorous concentrations are usually low [51]. COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : Western redcedar can be planted on disturbed sites within its natural range.  The erosion-control potential and long-term revegetation potential of western redcedar have been rated as medium [13].  Western redcedar may be the species of choice for reforesting high, brush-risk areas near the coast [50].  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 [38].  Containerized western redcedar appears to perform somewhat better than bareroot stock [26].  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]. 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 [50].  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 [8]. 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]. OTHER MANAGEMENT CONSIDERATIONS : 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 [50]. 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 [50]. 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 [50]. 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 [50].  Grazing by cattle in burned stands in the western redcedar/queencup beadlily (Clintonia uniflora) habitat type in southwestern Montana retards establishment of western redcedar [36]. 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 [50].  It is also sensitive to atmospheric pollution.  Clay dust from a brick works in British Columbia produced a columnar form in nearby western redcedars [51]. 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 [13]. 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 [51].  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 [26]. 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 [26].  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].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Thuja plicata
GENERAL BOTANICAL CHARACTERISTICS : 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 [8]. Western redcedar has a swollen or buttressed base, pointed conical crown, and horizontal branches curving upward at the tips [80].  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) [51].  The cones are clustered near the ends of twigs and become turned up on short stalks [80].  Western redcedar retains its lower limbs except when in densely crowded stands [8]. 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 soil [50,51]. RAUNKIAER LIFE FORM :       Phanerophyte REGENERATION PROCESSES : Seed production and dissemination:  Western redcedar reproduces from seeds more readily in open, disturbed areas, such as clearcuts, than in undisturbed stands [19].  Seed production normally begins when trees are 20 to 30 years old [73].  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 [50].  Pure stands of western redcedar may yield 60,704,168 seeds per acre (150,000,000/ha).  Poor cone crops are rare [19].  Large seed crops occur every 3 to 4 years [19,51]. 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) [50].  Stratification may improve the germination of some dormant seed lots.  However, in others it may lower the germination capacity [51]. Haig [34] reported germination rates of 73 percent, and Schopmeyer [69] 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 [19].  Rotten wood that is in contact with the soil is the preferred seedbed in old western redcedar groves [50]. Graham [26] 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 [19].  Seedlings show high resistance to root flooding [47] and respond well to removal of competition [57].  In one study, removal of shrubs resulted in an increase in height growth of western redcedar compared to unreleased trees [26]. 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 stands [26]. Vegetative reproduction:  Communities with closed canopies favor vegetative reproduction over sexual reproduction [32].  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 [28].  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 trees [19,32,58]. SITE CHARACTERISTICS : 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 [8].  In Glacier National Park and the Selway-Bitterroot Wilderness in Idaho and Montana, western redcedar is dominant in wet ravines and poorly drained depressions [50]. 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 [50].  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 [50].  Bottomland frost pockets in northern Idaho are commonly occupied by subalpine fir (Abies lasiocarpa) rather than western redcedar [51]. 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 [50]. Elevation:  Elevational ranges of western redcedar have been reported as follows [19,50,51]:         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) [35,50,51,61]. 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]. SUCCESSIONAL STATUS : 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 [25].  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 [50].  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 [51].  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)[32].  It can survive as a late-seral or coclimax tree on western-hemlock-dominated sites [21].  In Idaho, western white pine (P. monticola) stands are slowly replaced by a western hemlock-western redcedar climax [51]. SEASONAL DEVELOPMENT : 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 [57].  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 [50].  Dry warm weather can cause earlier seed release. Some seeds may be retained in the cones and gradually shed throughout the winter [19].  Where moisture and temperature conditions are favorable, germination can occur in the autumn, winter, or spring [50]. Along the coast region, seeds generally germinate in either fall or spring [8].

FIRE ECOLOGY

SPECIES: Thuja plicata
FIRE ECOLOGY OR ADAPTATIONS : Western redcedar fire resistance is low to moderate [21].  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 [21].  Old western redcedar trees are commonly fire scarred in northern Idaho [51]. 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 [50]. 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 [10].  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 [82].  In the Selway-Bitterroot Wilderness those stands dominated by western redcedar had the longest fire regime [29]. POSTFIRE REGENERATION STRATEGY :    Tree without adventitious-bud root crown    Secondary colonizer - off-site seed

FIRE EFFECTS

SPECIES: Thuja plicata
IMMEDIATE FIRE EFFECT ON PLANT : 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 [21].  Shallow roots under the duff layer are often scorched when the duff layer burns and even surface fires may kill western redcedar [51].  Fire injury to roots can lead to fungal infection, chronic stress, and growth losses [65].  The most common causes of fire mortality are root charring and crown scorching [70]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : After fire, western redcedar will readily establish on bare mineral soil 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 [50]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 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. FIRE MANAGEMENT CONSIDERATIONS : Riparian stringers supporting western redcedar may act as firebreaks because the moist duff does not readily burn [21].  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 fires [29].   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 [51]. 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 [51]. 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 [23].  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.

References for species: Thuja plicata


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10. Arno, Stephen F. 1985. Ecological effects and management implications of Indian fires. In: Lotan, James E.; Kilgore, Bruce M.; Fisher, William C.; Mutch, Robert W., technical coordinators. Proceedings--Symposium and workshop on wilderness fire; 1983 November 15-18; Missoula, MT. Gen. Tech. Rep. INT-182. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: 81-86. [7357]
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