Thuja plicata

Encyclopedia : T : TH : THU : Thuja plicata

Thuja plicata (Western Redcedar) is a species of thuja, an evergreen coniferous tree in the cypress family Cupressaceae, native to the northwestern United States and southwestern Canada, from southern Alaska and British Columbia south to northwest California and inland to western Montana.

Quinault Lake Redcedar, largest in the world

The foliage forms in flat sprays with scale-like leaves in opposite pairs, the successive pairs at 90° to each other. The foliage sprays are green above, and green marked white with stomatal bands below. The cones are slender, 15-20 mm long and 4-5 mm broad, with 8-12 thin, overlapping scales.

Western Redcedar is a large tree, to 50-60 m tall and 3 m (exceptionally 6 m) trunk diameter. The Quinault Lake Cedar (left) is the largest known Western Redcedar in the world with a wood volume of 500 cubic meters. Located near the northwest shore of Lake Quinault north of Aberdeen, Washington, about 34 km from the Pacific Ocean, it is 53.0 m high with a diameter of 5.94 m (Van Pelt, 2001).

It is among the most widespread trees in the Pacific Northwest, and is associated with Douglas-fir and Western hemlock in most places where it grows. In addition to growing in lush forests, Western Redcedar is also a riparian tree, and grows in many forested swamps and streambanks in its range. The tree is shade-tolerant, and able to reproduce under dense shade.

Western Redcedar is the Provincial tree of British Columbia. It is also known (mainly in the American horticultural trade) as Giant Arborvitae. The name Western Redcedar is also sometimes split into three words as 'Western Red Cedar', though this can cause confusion, as it is not a cedar.

Uses

T. plicata in a plantation at Polipoli, Maui, Hawaii

The soft red-brown timber is valued for its resistance to decay, being extensively used for outdoor construction in the form of posts, decking, shingles, siding, and so forth. It is cultivated as an ornamental tree and also (to a limited extent) in forestry plantations and for screens and hedges. It has been introduced to other parts of the temperate zone, including western Europe, New Zealand, the eastern United States and higher elevations of Hawaii. It is also used to line closets and chests, for the pungent aromatic oils from the wood are believed to discourage moth larvae, which can damage cloth by their eating. This is of course more effective in a properly constructed redcedar chest (sometimes made entirely of cedar), since the oils are confined by shellac and leather seals. A well sealed redcedar chest will retain its pungent odor for many decades, sometimes over a century.

Aboriginal Uses

Western redcedar has an extensive history of use by the Native American people of the northwest coast of North America, from Oregon to southeast Alaska. Its wood is used to make canoes, totem poles, houses, masks, helmets, armor, boxes, utensils, tools, and many other art and utility objects. Some northwest coast tribes refer to themselves as "people of the redcedar" because of their extensive dependence on the tree for basic materials.

Bark

The bark is easily removed from live trees in long strips, and 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 only harvests from trees which have not been stripped before, and usually less than a half round of the bark is removed. 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, and 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 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 m 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.

Wood

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.

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, and 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, and 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, and 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, but if it was 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.

Reference and external links

Conifer Specialist Group (1998). [Thuja plicata]. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.

Wikimedia Commons has media related to:

[Special]

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.