WESTERN RED CEDAR, Thuja plicata Donn ex D. Don.

Introduction:

Western redcedar (Thuaja plicata Don ex D. Don) is a member of the Cupressaceae, or cypress, family of conifers. The common name of "cedar" is misleading, as it applies only to the genus Cedrus, that is not native to North America. The massive western redcedar grows along much of the West Coast of Canada and the United States (Fig. 1). The Indians of the Pacific Northwest carved totem poles and canoes from this majestic tree and continue to hold it in high regard. In 1988 British Columbia named the western redcedar the official tree of the province (Gonzalez, 1997). It is one of the most important timbers in British Columbia’s economy.

The western redcedar has a very high resistance to disease and decay, making it very desirable for a variety of building purposes. As a result of its functionality in building, it has been extensively harvested for quite some time and is rapidly declining in abundance and quality.

Fig. 1. Western redcedar mixed with other species in British Columbia.

Geographical Distribution.

Western redcedar grows along the pacific coast of North America from northern California to southeastern Alaska (Fig. 2). It can also be found in Idaho and Montana but not as frequently. It is usually restricted to regions having abundant precipitation and humidity (Owens, 1984). In Canada, western redcedar growth is confined to British Columbia where it grows in close proximity with a number of other trees. Western redcedar is rarely found in isolation and most commonly shares its ranges on the Pacific slope with western hemlock, Douglas fir, grand and amabilis firs, Pacific yew, red alder, black cottonwood, and bigleaf maple. In the mountain stands it keeps the company of western larch, western white pine, western hemlock, grand fir and Engelmann spruce (Gonzalez, 1997).

Fig. 2. Main concentrations of the western redcedar.

The western redcedar is limited to regions with a reasonably mild climate and a significant growing season and is thus found at specific elevations at different latitudes (Owens, 1984). In Alaska it can only grow from sea level to 915 meters, while in British Columbia it can thrive up to 1200 meters on the coast and from 320 to 2130 meters in the interior. Interestingly, at elevations above 1500 meters it is most often a small tree or a shrub. In Washington, Oregon and California it can survive at increased elevations, as the climate becomes more hospitable to the south (Gonzalez, 1997). It grows best on alluvial sites, moist sediment deposited by flowing water as in a delta or riverbed, but is also found on rich dry soils and in sphagnum bogs.

Western redcedar has been recognized for its value and is grown outside of its natural range. It has been occasionally planted as an ornamental tree in the north Atlantic United States, in southern Australia, Britain and Switzerland. It has been used for practical forestry in England, Ireland, Scotland and is almost a naturalized species in West Germany. It is grown in Italy, France and the Scandinavian countries as well as extensively in New Zealand (Gonzalez, 1997).

Historical Uses.

The Cedar has played an incredible and interesting role in history. King Solomon built his famous Temple at Jerusalem from the cedars that he obtained from the King of Lebanon (Watkins, 2000). Long before that the North American Aboriginal people along the lush moist Pacific Coast used the tall majestic western redcedar as a pillar of their culture. As the Plains Indians efficiently used the buffalo, the Pacific Coast Indians used every part of the redcedar and made a myriad of items (Wood, 2000). Large logs were carved into totem poles, and thanks to the incredible durability of the redcedar wood many have been preserved as a source of insight into this grand culture as it was in the past. Logs were also hollowed out to make huge ocean-going canoes, one of which is on display at the Canadian Museum of Civilization measuring 16 meters long and 1.8 meters wide (Laird, 1995). Redcedar logs were also split into wide planks used to build large shelters. Excavations have unearthed redcedar planks at Indian sites believed to be between 6,000 and 10,000 years old. The stringy bark was used to make ropes, baskets, blankets and clothing. The flexible young branches were also used in making baskets, while older branches were used for arrows, even the roots were used for fishhooks (Massie, 1987).

In the 16^th century, extracts of this plant were given to members of the Jacques Cartier expedition as a cure for scurvy (Gonzalez, 1997). Not only was the tree a source of many temporal items, but it was also regarded highly for its healing and spiritual powers, as has been reflected in their art and culture. In light of it extensive importance to the Aboriginal people of the pacific west coast the western redcedar, Thuja plicata, was referred to as the "tree of Life" or "arbor-vitae."

Ecology.

As was explained in the geographical distribution section, the western redcedar grows in association with a number of other tree species. It thrives on moist alluvial sites and is also found on rich dry soils and in sphagnum bogs (Laird, 1995). In these locales the tree faces a variety of challenges from disease, insects, fungi, and other pests. Rarely do these challenges pose a serious problem because of the western redcedars’ natural resistance. This resistance is granted by its extractives, mainly the thujaplicins (Gonzalez, 1997). Of all the native tree species to British Columbia, the western redcedar has the highest resistance to fungi and disease.

One of the few diseases to have any success against the tree is commonly referred to as "cedar leaf blight," scientifically referred to as Didymascella thujina (Durand) Maire. It appears on trees of all size, but most commonly on young seedlings and the lower branches of older trees. The infected brown leaves are conspicuous against the healthy green foliage(Allen, 1996). The disease is commonly confused with the normal color changes that occur in the autumn.

Thee tree lives longer than most conifers and over the years the natural fungitoxic nature of the heartwood is diminished by repeated fungi invasions. This paves the way for future evasions and in rare cases the center of the tree can be hallowed out by fungi (Gonzalez, 1997). The two most destructive culprits are Ceriposiopsis rivulosa and Perenniporia subacadia (Allen, 1996).

Seldom do insects cause damage to the western redcedar, but a few species can present a problem. Mayetiola thujae, a cone midge that may infest all of the cones can seriously damage the tree. Bark beetles are opportunistic and will attack stressed trees and sometimes cause death. A third insect that can damage the tree is Trachykele blondeli, a flatheadded wood borer. The larval tunnels into healthy trees in coastal British Columbia leaving a maze of holes in the tree reducing the quality of the wood (Gonzalez, 1997).

Some mammals such as elk and deer feed on western redcedar seedlings and saplings. Black bears remove the bark and feed on the exposed sapwood. Of course none of these pose a threat to the survival of the species, just to the profits of the industry. Only humans assert a large scale threat to the western redcedar.

Thankfully fire is relatively rare in the regions where the western redcedar grows, because the needles are quite flammable and the shallow root system is readily killed by forest fires (Fonda, 1998)

 

Anatomical/Morphological Features.

The western redcedar is a very large tree, up to 60 meters tall and 2.5 meters in diameter and grows for up to 800 years. The trunk is oftern buttressed and the root system is shallow, wide-spreading and strong. The bark is thin, rarely over 2.5 cm thick and is reddish brown in color. The bark is smooth and shinny when young but becomes shredded and stringy with age. The crown is long and narrow often extending to the base of the tree. The primary branches droop down but turn upward at the ends. The leaves are shiny green and scale-like, 1-6 mm long and have inconspicuous resin glands on the surface. The tree produces a massive number of cones, (Fig. 3) which are ovoid, 12 -18 mm long and have spine tipped scales (Laird, 1995).

Fig. 3. Seed cones with a hard tips, growing in great numbers.

The reproductive cycle of the western redcedar is similar to that of most conifers. Cone initiation occurs in the first year, and pollination, fertilization and ovule and seed development occurs in the second year (Owens, 1984). This cycle is well adapted to the long mild growing seasons characteristic of the pacific West Coast.

The western redcedar must produce a massive number of seed cones, because each one only bears a few seeds. The seeds themselves are small and light but have very small seed wings and thus fall fast and within 120 meters of the source. Trees can begin producing seeds when they are quite young, 15 years old. The abundance of cones and the early cone production is required to offset the high number of ovule abortions and limited dispersal. The resulting seeds have two cotyledons, and germinate to produce a shoot apex with short primary needle-like leaves, three to a whorl. During the first growing season lateral branches are initiated, forming the scale-like decussate leaves and flattened branches of the mature tree (Owens, 1984).

Harvesting Techniques.

As you can imagine the western redcedar has been extensively harvested for a variety of commercial uses. In the past few decades we have begun to realize that this resource, as abundant as it once was is now quite diminished. The supply of old-growth redcedar is rapidly declining and is being replaced with a resource that is predominantly second growth. Studies have shown that the fast grown second-growth trees have a lower wood density and a natural decay resistance than the old growth (Gonzalez, 1997). Ironically, further greed and emphasis on rapid growth via genetic modification and silviculture may continue to reduce the wood quality for which it became so desirable.

The methods of harvesting are dependent upon the intended use. In applications that call expressly for redcedar it must be selected from amongst the other tree species with which it grows. One of the characteristics that make redcedar so valuable industrially is also a hindrance to its harvestability. The ease of splitting that facilitates handsplit shakes so well also causes significant losses in harvesting. When the trees are felled on rough hills and transported with heavy machinery breakage and splitting are often a problem (Massie, 1987).

The extensive logging that depleted the redcedar called for artificial regeneration, which began in British Columbia in the late 1960’s and early 1970’s. In 1987, 20% of the seedlings planted in coastal British Columbia were western redcedar (Gonzalez, 1997). The present methods of commercial seed extraction and germination used to produce seedlings for planting are quite specific. Harvested cones are kiln dried for 18 to 20 hours at 41 degrees Celsius. Lower temperatures are used if the cones have already begun to open naturally. Most of the seeds will be released during the drying or during the subsequent tumbling o the cones. The best germination is obtained if the seeds are soaked for 24hours in water, blotted dry and placed in incubation. Incubation is most effective at 20 to 30 degrees Celsius with 8 hours of light per day for 21 days (Owens, 1984).

Once the seedlings are large enough to manually plant they provide hours of outdoor enjoyment for those students dedicated enough to undertake a summer of planting for 10 cents per tree. Unfortunately, seedling mortality is very high in western redcedar. They are susceptible to fungi, birds, insects and grazing animals. In full sunlight few seedlings survive the high surface soil temperatures since their root system remains quite shallow. They survive best is partial shade, which is part of the reason that they are most successfully planted amongst other species (Owens, 1984).

Fertilization is becoming commonplace, though it seems strange to consider fertilizing an entire forest of redcedar. A recent study was undertaken to evaluate the potential of using organic fertilizers versus chemical fertilizers in northern Vancouver. The study hypothesized that organic fertilizers would have longer lasting positive effects on growth than chemical products. Unfortunately, the study concluded that the effects were no different in magnitude or duration (Prescott, 1998). Therefore industries will continue to use chemical products as they are much easier to apply. If organic mater such as biosolids, fish silage and paper sludge had proved to effect growth for a longer duration this may have justified their use, despite being more difficult to administer.

Commercial Uses and Impact on Humans.

The extensive use of the western redcedar by the pacific coast Aboriginals has been used as a model for modern society, as we have found uses for almost the entire tree. The wood is valued for canoe and boat building and is also still used to build timber frame structures. It is used for shakes, shingles and exterior siding as well as doors, window frames, and interior finishing (Massie, 1987). The list of uses continues; utility poles, fences, pulp and paper, boxes, beehives and even fish trap floats. Some of the major uses will be discussed at length after the characteristics of the wood that make it so versatile are explained.

Western redcedar is light, non-resinous and easy to work with. It has exceptional dimensional stability meaning that it will not shrink and swell very much, thus structures made of redwood will not easily warp. It is also a good thermal insulator making it a great roofing material that can actually reduce a buildings heating demands. Western redcedar also takes and holds paint and stains very well, although because of its beautiful color and natural decay resistance it is often left natural. The beautiful color and famous scent of the western redcedar are due to the natural presence of preservative and fungicidal substances that also adorn the wood with its remarkable durability (Wilson, 1993).

Now to illustrate the main commercial uses, shakes and shingles are the chief western redcedar products produced in British Columbia (Fig. 4). Both are a type of roof covering, differing primarily in cut, thickness and size. Both provide a lovely alternative to conventional shingling. British Columbia accounted for 80% of the total global production of shakes and shingles in 1996. About 90% of which were shipped to the United States for distribution (Gonzalez, 1997). This product is a perfect application of western redcedar wood due to its lightweight, dimensional stability and natural durability. Recall that second growth trees are fast growing and poorer in quality, these are ideally not used for shakes and shingles. Only old, slow grown, straight grained and highly durable wood is suitable for manufacturing these roof coverings (Massie, 1987). These can also be applied directly over the existing roofing to reduce roofing costs. Despite the woods natural durability the growing trend towards more gradual roofs causes slower runoff and therefore may necessitate chemically treated wood.

Fig. 4. Cedar Shakes used for roof covering.

One of the fastest growing segments of the market for western redcedar wood is the outdoor living market. The woods durability makes it a natural choice for yard accessories. Decks and fences retain their shape and resist discoloration. If you are lucky enough to have a hot tub on your deck the wood provides low thermal conductivity and a pleasant scent making it ideal for moist, humid conditions (Wilson, 1993). Redcedar wood is very popular as planters and flowerpots since the oils and fungicides in the wood resist rot. Conversely these volatile oils can cause fruit to spoil and redcedar wood is therefore inappropriate for fruit storage, such as apple boxes. An array of outdoor furniture is quite fashionable in western redcedar wood, as are garden sheds, gazebos, greenhouses and trellises (Wilson, 1993). Western redcedar is also used for playground equipment in combination with plastics and metals.

Western redcedar is also a very important export from British Columbia in the form of lumber. In 1996, British Columbia produced 926 million board feet of western redcedar lumber, representing 7% of the provinces total lumber production. Seventy- seven percent of which was shipped to the United States, valued at $538 million Canadian dollars (Gonzalez, 1997). There is also a substantial market overseas for this lumber and shipping takes place to most of Europe.

The European market has historically viewed western redcedar as too expensive relative to pine, but that is beginning to change. The new second growth wood is of poorer quality and may contain knots, thus it is being marketed for outdoor uses at a price only 10-20% above the treated pine price (Wilson, 1993). The garden and leisure industry is a lucrative business right now, and the western redcedar provides a beautiful wood perfect for outdoor applications.

One of the most substantial industrial uses of trees is not particularly appropriate for western redcedar wood, that being pulp and paper. The low density of the wood is the most serious impediment to its use in pulping. Here is the problem, pulp is produced and sold by weight, but the logging industries work by volume. Having a low density means that a given volume of western redcedar will in effect contain less wood and therefore produce less pulp that other softwood species (Massie, 1987). The relatively high lignin content in the wood and the characteristic extracts are also obstacles that make it less desirable for pulping. One more feature of the western redcedar that makes it less popular for pulping is its stringy bark. Standard debarking equipment is unable to effectively remove the bark so chemical procedures have been developed. Some methods have been developed that are able to utilize this tree effectively to make pulp and paper, but at increased expense (Massie, 1987). Its seems as though western redcedar is destined to be used in more stately manners such as building, rather than being relegated to becoming the morning newspaper. Since there are so many uses for good quality western redcedar wood, only the lowest grade or damaged trees end up as paper.

Extractives from the western redcedar are being examined for marketability. Oil from the leaves and branch ends is being tested for uses as insecticides, fungicides and for use in the perfume industry (Gonzalez, 1997). The thujaplicins have been tested as chemotherapeutic agents, fungicides, and germicides because they have antibiotic properties, but no commercial use has been developed yet (Gonzalez, 1997).

In an effort to be efficient, industries have found uses for the waste material remaining after shake and shingle and lumber production. The sawdust is used in pulping and as a rooting medium. The sawdust was also used to fill in marshes and bogs during the building of the Trans-Canada highway (Massie, 1987).

The western redcedar has very little direct impact on humans outside of the uses discussed. Plicatic acid, one of the extractives is responsible for allergies to the tree which are most severe upon exposure to sawdust (Gonzalez, 1997).

Future Developments.

The western redcedar has been so extensively harvested that improved regeneration methods are needed. Its’ natural regenerative capacity is no longer adequate because old growth stands are becoming rare. Seed orchards are becoming common, as seeds are becoming scarcer in the wild (Owens, 1984). Geneticists have produced strains that grow faster but with poorer wood quality so this is obviously an area in which future improvements are desired.

The other aspect of the industry that is currently being developed is the extractives market. A cost-effective method of extracting the desired oils from the residues is still not commercially available. Most of the testing that is carried out on the extracts is done on residues gathered from the machines used to process the wood into products (Owens, 1984). The possible uses of these extracted compounds are still being studied. Medicinal possibilities are significant, as is the potential of developing an organic fungicide (Gonzalez, 1997).

Summary

The western redcedar is one of the most durable and beautiful tree species in North America. The wood is easy to work with and has been used in a number of industrial products, primarily shakes and shingles. The extracts of the tree have chemical properties that suggest a multitude of uses, but none have been developed into a cost-effective marketable product.

The western redcedar is being harvested at a rate faster than it can sustain, despite its solid regenerative capacity. Planting of nursery-grown seedlings is essential to the survival of the industry. The reserve of old growth western redcedar is in quick decline, and is being replaced with second growth trees that are of poorer quality. For the industry to continue resource management is crucial or fast growing trees of better quality must be engineered. A troubling theme arises here; only when the financial gains that a resource provides becomes jeopardized do we attempt to repair the resource.

References

Allen, E. A. & Morrison, G. W. 1996. Common tree diseases of British Columbia. Natural Resources Canada, Canadian Forestry Services. p.108.

Fonda, R.W. & Belanger, L.A. 1998. Burning characteristics of western conifer needles. Northwest-Science. 72(1): 1-9.

Gonzalez, J.S. 1997. Growth properties and uses western redcedar. Forintek Canada Corporation. Vancouver.

Laird, J. 1995. Trees in Canada. Co-published by the Canadian Forest Service in cooperation with the Canada Communication Group, Publishing. 24-25.

Massie, M. 1987. Utilization opportunities for Western Redcedar. Forest resource development agreement. Published by the Canadian Forestry Service. Victoria.

Owens, J. 1984. The reproductive cycles of the western redcedar and the yellow-cedar. British Columbia, Ministry of Forests. Research Branch. Published by Information Services Branch.

Prescott, C.E. & Brown, S.M. 1998. Five year growth response of western redcedar, western hemlock, and amabilis fir to chemical and organic fertilizers. Can. J. Forest Research. 28(9): 1328-1334.

Watkins. Timeless Beauty: the history of cedar. http://watkinsawmills.com/history.htm, 02/28/2000

Wilson, B., Ennis, R. & Fisher, P. 1993. Western redcedar market potential in Europe. Canada-British Columbia partnership agreement on forest resource development. Published by Simons Strategic Services. Vancouver.

Wood. Western redcedar. http://www. cyberyard,com/cybyrdnat’/wdgdlibrary/wdgdwestredcedar.html, 02/01/2000