| Sitka spruce | |
|---|---|
 | |
| Sitka spruce in theHoh Rainforest inOlympic National Park | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Picea |
| Species: | P. sitchensis |
| Binomial name | |
| Picea sitchensis | |
 | |
| Range highlighted in dark green | |
| NCBI ID | 3332 |
|---|---|
| Ploidy | 2 |
| Genome size | 20 Gbp |
| Number ofchromosomes | 12 |
| Sequencedorganelle | plastid and mitochondrion |
| Organelle size | 124 kbp and 5.52 Mbp |
| Year ofcompletion | 2016 and 2019 |
Picea sitchensis, theSitka spruce, is a large,coniferous,evergreen tree growing to just over 100 meters (330 ft) tall,[3] with a trunkdiameter at breast height that can exceed 5 m (16 ft). It is by far the largest species ofspruce and the fifth-largest conifer in the world (behindgiant sequoia,coast redwood,kauri, andwestern redcedar),[4] and the third-tallest tree species (after coast redwood andSouth Tibetan cypress). The Sitka spruce is one of only three speciesdocumented to exceed 100 m (330 ft) in height.[3] Its name is derived from the community ofSitka in southeast Alaska, where it is prevalent. Its range hugs the western coast of Canada and the US and continues south into northern California.
Thebark is thin and scaly, flaking off in small, circular plates 5–20 centimeters (2–8 in) across. The inner bark is reddish-brown.[5] The crown is broad conic in young trees, becoming cylindric in older trees; old trees may not have branches lower than 30–40 meters (98–131 ft). The shoots are very pale buff-brown, almost white, and glabrous (hairless), but with prominentpulvini. Theleaves are stiff, sharp, and needle-like, 15–25 millimeters long, flattened in cross-section,[5] dark glaucous blue-green above with two or three thin lines ofstomata, and blue-white below with two dense bands of stomata.
Thecones are pendulous, slender cylindrical, 6–10 cm (2+1⁄2–4 in) long[6] and2 cm (3⁄4 in) broad when closed, opening to3 cm (1+1⁄4 in) broad. They have thin, flexible scales15–20 mm (5⁄8–3⁄4 in) 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. Theseeds are black,3 mm (1⁄8 in) long, with a slender,7–9 mm (1⁄4–3⁄8 in) long pale brown wing.
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 inPacific Rim National Park andCarmanah Walbran Provincial Park onVancouver Island, British Columbia (the Carmanah Giant, at 96 m (315 ft) tall, is the tallest tree in Canada),[7] and inOlympic National Park,Washington andRedwood National Park, California (United States), the latter of which houses the tallest individual measuring at 100.2 meters or 329 feet tall;[3] two others at the last site are just over 96 m tall.[8] The Queets Spruce is the largest in the world with a trunk volume of 346 m3 (12,200 cu ft), a height of 74.6 m (244 ft 9 in), and a 4.4 m (14 ft 5 in)dbh.[9][10] It is located near theQueets River inOlympic National Park, about 26 km (16 mi) from the Pacific Ocean. Another specimen, fromKlootchy Creek Park, Oregon, was previously recorded to be the largest with a circumference of 15 metres (49 ft) and height of 66 metres (217 ft).
Sitka spruce is a long-lived tree, with the oldest known individual just under 600 years old.[8] 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.[11]
Because it grows in extremely wet and poorly-drained soil, the Sitka spruce has a shallowroot system with long lateral roots and few branchings. This also makes it susceptible to wind throw.[12]
DNA analysis[13][14] has shown that onlyP. breweriana has a morebasal position than Sitka spruce to the rest of the spruce. The other 33 species of spruce are morederived, which suggests thatPicea originated in North America.[13]
Sitka spruce is native to the west coast of North America, with its northwestern limit onKenai Peninsula,Alaska, and its southeastern limit nearFort Bragg in northern California.[15] It is closely associated with thetemperate rainforests 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 seldom does its range extend more than around 80 km (50 mi) from the Pacific Ocean and its inlets.[5] It is situated at about 2,500 m (8,200 ft) above sea level in Alaska and generally below 450 m (1,480 ft) further south.[5]
Forests with the species average between 200 and 500 cm (79 and 197 in) of rain annually.[5] It is tolerant to salty spray common in coastal dune habitat, such as atCape Disappointment State Park in Washington, and prefers soils high in magnesium, calcium, and phosphorus.[12]
Sitka spruce has been introduced to Europe as a lumber tree, and was first planted there in the 19th century. Sitka spruce plantations have become a dominant forest type in Great Britain and Ireland, making up 25% of forest cover in the former and 52% in the latter. Sitka spruce woodland is also present in France and Denmark, and the plant was introduced to Iceland and Norway in the early 20th century.[16][17] Observations of Sitka spruce along the Norwegian coast have shown the species to be growing 25–100% faster than the native Norway spruce there, even as far north asVesterålen, and Sitka spruces planted along the southwest coast of Norway are growing fastest among the Sitka plantations in Europe.[18][19]
A 9-metre-tall, 100-year-old Sitka spruce growing in the middle of the permanently uninhabited sub-antarcticCampbell Island has been recognised by the Guinness World Records as the "most remote tree in the world".[20]
Sitka spruce provides critical habitat for a large variety of mammals, birds, reptiles, and amphibians. Its thick, sharp needles are poor browse forungulates, and only the new spring growth is eaten. However, in Alaska and British Columbia the needles ofPicea sitchensis comprise up to 90% of the winter diet ofblue grouse.[12]
Lichen-forming fungiHelocarpon lesdainii is found onPicea sitchensis trees inHarris Beach State Park, Oregon, US.[21]
It provides cover and hiding places for a large variety of mammals, and good nesting and roosting habitat for birds.Sitka deer require old-growth Sitka spruce forests for winter habitat, as the extensive foliage holds a significant percentage of fallen snow in a given area, thus allowing for better understory browsing and easier migration for terrestrial animals. Cavity nesting birds favor Sitka spruce snags, and the tree is used bybald eagles,[5] andperegrine falcons as nesting habitat.
Sitka spruce isshade tolerant but not as much as its competitors,[5] preferring full sun if possible. It is apioneer on landslides, sand dunes, uplifted beaches, and deglaciated terrain. However, it is aclimax species in coastal forests, where it can become dominant.[12]
Due to the prevalence of Sitka spruce in cool, wet climates, its thin bark and shallow root system are not adapted to resistfire damage and it is thus very susceptible. Sitka spruce forests have afire regime of severecrown or surface fires on long intervals, (150 to 350+ years) which results in total stand replacement. Sitka spruce recolonizes burned sites via wind-dispersed seed from adjacent unburned forests.[12]
The root bark of Sitka spruce trees is used inNative Alaskan basket-weaving designs[22] and for rain hats. The pitch was used forcaulking, chewing, and its medicinal properties.[12] Native Americans heated and plied the roots to make cord.[5] The resin was used as glue and for waterproofing.[5] Natives and pioneers split offshakes for construction use.[5] The wood is light and relatively strong.[5]
Sitka spruce is of major importance inforestry 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 prosper; in ideal conditions, young trees may grow 1.5 m (5 ft) per year. It is naturalized in some parts of Ireland and Great Britain, where it was introduced in 1831 byDavid Douglas,[23] and New Zealand, though not so extensively as to be consideredinvasive. Sitka spruce is also planted extensively in Denmark, Norway, andIceland.[24][25] 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 fromVest-Agder in the south toTroms in the north. It is more tolerant to wind and saline ocean air, and grows faster than the nativeNorway spruce.[26] But in Norway, the Sitka spruce is now considered an invasive species, and effort to eliminate it is being made.[27][28]
The resonant wood[5] 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.[citation needed] For these reasons, the wood is also an important material forsailboatspars, and aircraft wing spars (including flying models).[citation needed] TheWright brothers'Flyer was built using Sitka spruce, as were many aircraft beforeWorld War II; during that war, aircraft such as the BritishMosquito used it as a substitute for strategically important aluminium.[citation needed]
Newly grown tips of Sitka spruce branches are used to flavorspruce beer and are boiled to makesyrup.[29][30]
A unique specimen with golden foliage that used to grow onHaida Gwaii, known asKiidk'yaas or "The Golden Spruce", is sacred to theHaida First Nations people. It was illegally felled in 1997 byGrant Hadwin, although saplings grown from cuttings can now be found near its original site.
In theLushootseed language, spoken in what is nowWashington state, it is known asc̓əlaqayac.[31]
The stilbene glucosidesastringin,isorhapontin, andpiceid can be found in the bark of the Sitka spruce.[32][33]
In the Olympic National Forest in Washington, Sitka spruce trees near the ocean sometimes developburls.
According to a guidebook entitledOlympic 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."[34]
This tree also has a sign nearby proclaiming it to be 'the world's largest spruce'. The two tallest on record, 96.7 m and 96.4 m, are in Prairie Creek Redwoods State Park, California
Efforts to remove this species have been initiated in Norway as the Sitka spruce dominates the native ecology with few native species managing to compete or thrive in its shadow.
