Picea sitchensis, the Sitka spruce, is a large, coniferous, evergreen tree growing to just over tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). 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 tree species (after coast redwood and South Tibetan cypress). The Sitka spruce is one of only three species documented to exceed in height. The crown is broad conic in young trees, becoming cylindric in older trees; old trees may not have branches lower than . 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 millimeters long, flattened in cross-section, and broad when closed, opening to broad. They have thin, flexible scales 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, long, with a slender, 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 tall may still be seen in Pacific Rim National Park and Carmanah Walbran Provincial Park on Vancouver Island, British Columbia (the Carmanah Giant, at tall, is the tallest tree in Canada), and in Olympic National Park, Washington and Redwood National Park, California (United States), the latter of which houses the tallest individual measuring at 100.2 meters or 329 feet tall; The Queets Spruce is the largest in the world with a trunk volume of , a height of , and a dbh. It is located near the Queets River in Olympic National Park, about from the Pacific Ocean. Another specimen, from Klootchy Creek Park, Oregon, was previously recorded to be the largest with a circumference of and height of .

Age

Sitka spruce is a long-lived tree, with the oldest known individual just under 600 years old.

Root system

Because it grows in extremely wet and poorly-drained soil, the Sitka spruce has a shallow root system with long lateral roots and few branchings. This also makes it susceptible to wind throw.

Burls

In the Olympic National Forest in Washington, Sitka spruce trees near the ocean sometimes develop 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."

Taxonomy

DNA analysis has shown that only P. breweriana has a more basal position than Sitka spruce to the rest of the spruce. The other 33 species of spruce are more derived, which suggests that Picea originated in North America. It is closely associated with the temperate 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 from the Pacific Ocean and its inlets. 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 as Vesterålen, and Sitka spruces planted along the southwest coast of Norway are growing fastest among the Sitka plantations in Europe.

A 9-metre-tall, 100-year-old Sitka spruce growing in the middle of the permanently uninhabited sub-antarctic Campbell Island has been recognised by the Guinness World Records as the "most remote tree in the world".

Ecology

thumb|Sitka spruce on [[Vancouver Island, British Columbia]]

Value to wildlife

Sitka spruce provides critical habitat for a large variety of mammals, birds, reptiles, and amphibians. Its thick, sharp needles are poor browse for ungulates, and only the new spring growth is eaten. However, in Alaska and British Columbia the needles of Picea sitchensis comprise up to 90% of the winter diet of blue grouse.

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 by bald eagles, and for rain hats. The pitch was used for caulking, chewing, and its medicinal properties. 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 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. However, the Sitka spruce is now considered an invasive species in Norway, and effort to eliminate it is being made.

The resonant wood

and are boiled to make syrup.

Needles can be used to make an aromatic tea.

Indigenous culture

thumb|upright=1.4|[[Kiidk'yaas in 1984]]

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 First Nations people. It was illegally felled in 1997 by Grant Hadwin, although saplings grown from cuttings can now be found near its original site.

In the Lushootseed language, spoken in what is now Washington state, it is known as .

Chemistry

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

See also

  • List of tallest trees

References

  • Picea sitchensis – information, genetic conservation units and related resources. European Forest Genetic Resources Programme (EUFORGEN)
  • Gymnosperm Database
  • 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'