Sitka spruce

Picea sitchensis

Summary 5

Picea sitchensis, the Sitka spruce, is a large, coniferous, evergreen tree growing to almost 100 m (330 ft) 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 conifer species (after coast redwood and coast Douglas-fir). The Sitka spruce is one of the few species documented to...

Description 6

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 (0.8 in) broad when closed, opening to 3 cm (1.2 in) broad. They have thin, flexible scales 15–20 mm (0.6–0.8 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. The seeds are black, 3 mm (0.1 in) long, with a slender, 7–9 mm (0.3–0.4 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 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 (United States); 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 346 m3 (12,200 cu ft), a height of 74.6 m (245 ft), and a 4.4 m (14 ft) dbh. It is located near the Queets River in Olympic National Park, about 26 km (16 mi) from the Pacific Ocean. Another specimen, from Klootchy 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 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.

As 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.

Sources and Credits

  1. (c) Mike Patterson, some rights reserved (CC BY-NC), uploaded by Mike Patterson
  2. (c) Roland Tanglao, some rights reserved (CC BY), http://www.flickr.com/photos/35034347371@N01/4694846207
  3. (c) Carita Bergman, some rights reserved (CC BY-NC-ND), uploaded by Carita Bergman
  4. (c) Axel Kristinsson, some rights reserved (CC BY), http://www.flickr.com/photos/57605412@N00/3677670153
  5. Adapted by Keri Pidgen-Welyki from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Picea_sitchensis
  6. (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Picea_sitchensis

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