Picea sitchensis

Picea sitchensis Sitka spruce
Quinault Lake Spruce, the largest member of the species according to American Forest by points
Conservation status
Least Concern (IUCN 2.3)
Scientific classification
Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Pinaceae
Genus:	Picea
Species:	P. sitchensis
Binomial name
Picea sitchensis (Bong.) Carr.
Range highlighted in dark green

Picea sitchensis, the Sitka spruce, is a large coniferous evergreen tree growing to almost 100 m (330 ft) tall, and with a trunk diameter at breast height that can exceed 5 m (16 ft) (see List of superlative trees). It is by far the largest species of spruce and the fifth largest conifer in the world (behind giant sequoia, coast redwood, kauri and western redcedar); and the third tallest conifer species (after coast redwood and coast Douglas-fir). The Sitka spruce is one of the few species documented to reach 91 metres (299 ft) feet in height. It acquires its name from the community of Sitka, Alaska.

Description

Foliage, mature seed cone and (center) old pollen cone

The bark is thin and scaly, flaking off in small circular plates 5–20 cm (2.0–7.9 in) across. The crown is broad conic in young trees, becoming cylindric in older trees; old trees may not have branches lower than 30–40 m (98–131 ft). The shoots are very pale buff-brown, almost white, and glabrous (hairless) but with prominent pulvini. The leaves are stiff, sharp and needle-like, 15–25 mm long, flattened in cross-section, dark glaucous blue-green above with two or three thin lines of stomata, and blue-white below with two dense bands of stomata.

The cones are pendulous, slender cylindrical, 6–10 cm (2.4–3.9 in) long and 2 cm broad when closed, opening to 3 cm broad. They have thin, flexible scales 15–20 mm long; the bracts just above the scales are the longest of any spruce, occasionally just exserted and visible on the closed cones. They are green or reddish, maturing pale brown 5–7 months after pollination. The seeds are black, 3 mm long, with a slender, 7–9 mm long pale brown wing.

Size

More than a century of logging has left only a remnant of the spruce forest. The largest trees were cut long before careful measurements could be made. Trees over 90 m (300 ft) tall may still be seen in Pacific Rim National Park and Carmanah Walbran Provincial Park on Vancouver Island, British Columbia (the Carmanah Giant, at 96 m (315 ft) tall, is the tallest tree in Canada), and in Olympic National Park, Washington and Prairie Creek Redwoods State Park, California (USA); two at the last site are just over 96 m tall. The Queets Spruce is the largest in the world with a trunk volume of 337 m³ (11,900 cu ft), a height of 75.6 m (248 ft), and a 4.55 m (14.9 ft) dbh. It is located near the Queets River in Olympic National Park, about 26 km (16 mi) from the Pacific Ocean.

Age

Sitka spruce is a long-lived tree, with individuals over 700 years old known. Because it grows rapidly under favorable conditions, large size may not indicate exceptional age. The Queets Spruce has been estimated to be only 350 to 450 years old, but adds more than a cubic meter of wood each year (Van Pelt, 2001).

Root system

Living in an extremely wet climate, the Sitka has a shallow root system with long lateral roots and few branchings.

Fire danger

Although Sitka spruce generally grows in cool, wet climates, its thin bark and shallow root system make it susceptible to fire damage.

Taxonomy

DNA analysis has shown that only Picea breweriana has a more basal position than Sitka spruce to the rest of the spruce. The other thirty-three species of spruce are more derived which suggests that Picea originated in North America.

Distribution and habitat

File:Sitka Spruce forest.jpg

Sitka spruce forest in the Olympic Mountains, Washington

Sitka spruce is native to the west coast of North America, with its northwestern limit on Kodiak Island, Alaska, and its southeastern limit near Fort Bragg in northern California (Griffin & Critchfield 1972). It is closely associated with the temperate rain forests and is found within a few kilometers of the coast in the southern portion of its range. North of Oregon, its range extends inland along river floodplains, but nowhere does its range extend more than 80 km (50 mi) from the Pacific Ocean and its inlets.

Uses

Felled Sitka spruce, Oregon Coast Range, 1918

Sitka spruce is of major importance in forestry for timber and paper production. Outside its native range, it is particularly valued for its fast growth on poor soils and exposed sites where few other trees can be grown successfully; in ideal conditions, young trees may grow 1.5 m (4.9 ft) per year. It is naturalized in some parts of Ireland and Great Britain where it was introduced in 1831 (Mitchell, 1978) and New Zealand, though not so extensively as to be considered invasive. Sitka spruce is also planted extensively in Denmark, Norway and Iceland. In Norway, Sitka spruce was introduced in the early 1900s. An estimated 50,000 hectares (120,000 acres) have been planted in Norway, mainly along the coast from Vest-Agder in the south to Troms in the north. It is more tolerant to wind and saline ocean air, and grows faster than the native Norway spruce.

Sitka spruce is used widely in piano, harp, violin, and guitar manufacture, as its high strength-to-weight ratio and regular, knot-free rings make it an excellent conductor of sound. For these reasons, the wood is also an important material for sailboat spars, aircraft wing spars (including flying models), and the nose cones of Trident missiles. The Wright brothers' Flyer was built using Sitka spruce, as were many aircraft before World War II; during that war, aircraft such as the British Mosquito used it as a substitute for strategically important aluminium.

Newly grown tips of Sitka spruce branches are used to flavor spruce beer and are boiled to make syrup.

The root bark of Sitka spruce trees is used in Native Alaskan basket-weaving designs.

Culture

A unique specimen with golden foliage that used to grow on Haida Gwaii, known as Kiidk'yaas or "The Golden Spruce", is sacred to the Haida Native American people. It was illegally felled in 1997 by Grant Hadwin, although saplings grown from cuttings can now be found near its original site.

Chemistry

The stilbene glucosides astringin, isorhapontin and piceid can be found in the bark of Picea sitchensis.

Sitka spruce trees with burls, Olympic National Forest, Washington

File:20150703 130609a.jpg

End grain on Picea sitchensis plank

Radially cut plank of Picea sitchensis

Burls

In the Olympic National Forest in Washington, Sitka spruce trees near the ocean sometimes develop tumors, also called burls. According to a guidebook entitled Olympic Peninsula, "Damage to the tip or the bud of a Sitka spruce causes the growth cells to divide more rapidly than normal to form this swelling or burl. Even though the burls may look menacing, they do not affect the overall tree growth."

See also

• List of superlative trees

External links

• Conifer Specialist Group (1998). Picea sitchensis. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 6 May 2006.
• Griffin, J. R. & Critchfield, W. B. 1976. Distribution of forest trees in California. USDA Forest Service Research Paper PSW-82: 23–24, 75.
• Mitchell, A. 1978. Trees of Britain & Northern Europe. Collins Field Guide. HarperCollins. London. ISBN 0-00-219213-6
• Gymnosperm Database
• Flora of North America
• Arboretum de Villardebelle - photos of cones of Picea sitchensis and related spruces
• Prof Stephen Sillett's webpage with photos taken during canopy research.
• Description of Sitka Spruce in forestry (PDF) by US Department of Agriculture.
• Picea Sitchinesis 'Octopus tree'