Sitka spruce (Picea sitchensis): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Picea sitchensis (Bong.) Carr., pine family
Other names	Tideland spruce, coast spruce and yellow spruce (Silvics); the Wood Handbook adds western, silver and west coast spruce
Native status, USDA PLANTS	Native in Alaska, Canada and the lower 48 states
Lifespan, Silvics	May live to 700 or 800 years
Green weight of the wood, NRS-38	33 lb per cubic foot, without bark

Native range

The Silvics of North America handbook (Agriculture Handbook 654, volume 1, 1990) calls Sitka spruce the largest of the world's spruces. It says the tree grows in a narrow strip along the north Pacific coast, from latitude 61 degrees N in south-central Alaska to 39 degrees N in northern California, and is seldom found far from tidewater, where moist maritime air and summer fogs keep conditions humid. The widest part of the range is in southeast Alaska and northern British Columbia, where it takes in a narrow mainland strip and the islands of the Alexander Archipelago and the Queen Charlotte Islands. Along the Gulf of Alaska the range is held in by steep mountains and glaciers edging the sea. In southern British Columbia the handbook says the best development is on the northern tip and west side of Vancouver Island. It says that through most of its range the tree grows with western hemlock in dense stands where growth rates are among the highest in North America.

Size and age

Silvics says mature trees near sea level in Alaska may exceed 61 m (200 ft) in height and 3 m (10 ft) in diameter at breast height. A tree 87 m (286 ft) tall is reported from Oregon. The largest tree on record, near Seaside, Oregon, is 5.1 m (16.7 ft) in diameter and 65.8 m (216 ft) tall with a crown spread of 28 m (93 ft). On average sites in southeast Alaska, the handbook says trees can be expected to reach about 27 m (90 ft) within 50 years after reaching breast height. It adds that few western hemlock live past 500 years, while Sitka spruce may live 700 or 800 years.

Cones and roots

The handbook says Sitka spruce is monoecious. Female cones are usually produced at the ends of primary branches near the tops of trees, and male cones at the ends of secondary branches lower in the tree. Individual trees may occasionally bear cones before age 20, but cone bearing in stands usually begins at ages 20 to 40, and cones ripen in the year they were pollinated.

On roots, Silvics says form varies from flat platelike roots to deep, narrow-spreading roots depending on the soil. Where soils are shallow, cold and infertile and water tables are high, shallow rooting is by far the most common. Rooting to depths of 2 m (6 ft) has been reported where soils drain well. The handbook says the species commonly produces long lateral roots with few branches, with lateral roots up to 23 m (75 ft) long observed in Alaska, and that roots of the same tree and of neighbouring trees graft together.

Wood

The Wood Handbook (FPL-GTR-282, 2021) says the heartwood of Sitka spruce is a light pinkish brown and the sapwood creamy white, with the sapwood 7 to 15 cm (3 to 6 in) wide or wider in young trees. It describes the wood as comparatively fine in texture, generally straight grained, moderately lightweight, moderately soft and moderately stiff, and says that on the basis of weight Sitka spruce rates high in strength. It lists lumber, pulpwood and cooperage as the principal uses, and names aircraft construction, ladder rails and piano sounding boards among the specialty uses. Silvics also lists guitar faces and oars, masts and spars for traditional boats. The Wood Handbook says much Sitka spruce timber is grown in Alaska but most logs are sawn into cants for export to Pacific Rim countries.

Wood Handbook figure	Green	At 12% moisture content
Specific gravity (Table 5-3b)	0.37	0.40
Modulus of rupture, lbf per square inch (Table 5-3b)	5,700	10,200
Side hardness, lbf (Table 5-3b)	350	510
Moisture content of green wood, percent (Table 4-1)	41 heartwood, 142 sapwood	Not applicable

The green weight of the wood is in the NRS-38 table, the same figure used in the log weight calculator.

Pests and diseases the handbook names

Silvics (1990) calls blowdown probably the most serious damaging agent of Sitka spruce and says problems with pests tend to be more severe toward the south of the range.

White pine weevil. Pissodes strobi, named as the most serious insect pest in Oregon, Washington and southern British Columbia and the most serious deterrent to management of Sitka spruce in the south of its range. The handbook says damage is most severe on young trees 3 to 6 m (10 to 20 ft) tall and that the weevil is not a problem on the Queen Charlotte Islands or in Alaska.
Spruce aphid. Elatobium abietinum, which feeds on Sitka spruce from California to Alaska and is a pest of ornamental trees, with epidemics the handbook calls sporadic and short lived.
Other insects. A root-collar weevil (Steremnius carinatus) that girdles seedlings one and two years old, and the spruce beetle (Dendroctonus rufipennis), which it says periodically damages stands throughout the range and is a major pest of spruce in British Columbia.
Decay. The handbook says the species is highly susceptible to decay when injured. It names Heterobasidion annosum and Armillaria mellea as organisms that cause decay in old growth and can also cause root rot in young stands, and says butt rot from H. annosum in plantation-grown trees is well known in Europe.
Foliage and animals. Foliage and stem diseases are usually of minor importance, with several rusts causing occasional light to moderate defoliation or witches' brooms. It lists damage from elk, bear, deer, porcupines, rabbits, hares and squirrels, and large tumor-like growths on stems in Washington and Alaska whose cause is not known.

The guide on reporting a pest in the United States gives the office that takes sightings of regulated pests, and pests and diseases by country sets out which ones agencies regulate. Who may apply pesticides is in pesticide licences by country.