Forest An American Service Sitka United States Department of Agriculture FS-265 Sitka spruce, the largest of the world’s , is one of the most prominent along the northwest coast c . It is seldom found far from tidewater, where moist maritime air and summer fog help maintain the humid conditions necessary for its growth. Throughout most of its range from northern to , Sitka spruce is associated with western hemlock in dense stands where growth rates are among the highest in North America. It is a valuable commercial timber species for , , and many special uses.

F-253874 An American Wood

Sitka Spruce ( (Bong.) Carr.) A. S. Harris1

Distribution

Sitka spruce grows in a narrow strip along the north Pacific coast from latitude 61 ° N. in south-central Alaska to 39° N. in northern California (fig. 1). It is restricted to an area of maritime climate with abundant moisture throughout the year, relatively mild winters, and cool summers. Sum- mer temperatures are lower in the nor- thern latitudes and lack the extremes found in the southern part of the range.

The most extensive portion of the range in both width and elevation is in and northern , where it extends for about 130 miles east to west and includes a narrow mainland strip, the many islands of the Alexander Archipelago in Alaska, and the Queen Charlotte Islands in British Columbia. North and west of southeast Alaska, along the Gulf of Alaska to Prince William Sound, the species is restricted by steep mountains and glaciers edging the sea. Within Prince William Sound, the range widens to about 60 miles to in- clude many offshore islands and nar- rows farther west. It extends across Cook Inlet to Cape Kubugakli and across Shelikof Strait to the islands of the Kodiak Archipelago.

In British Columbia, the range includes a narrow mainland strip and offshore islands. The best development is on the Queen Charlotte Islands. On , the best development is on the northern tip and west side. On the east side of Vancouver Island and on the mainland south to , the species tends to be restricted to sea-facing slopes and valley bottoms.

1Principal Silviculturist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station, F-532742 2 An American Wood

Figure 2–Mature Sitka spruce. F-397927

In Washington, Sitka spruce grows in a heteropylla) throughout most of its and hybrids occur. The most important narrow mainland strip along the Strait range. Toward the south, other associates are red of Georgia, around Puget Sound, up associates include Douglas- (Pseudot- () and bigleaf (Acer river valleys to the east, and on the suga menziesii), Port-Orford-cedar macrophyllum) in the south and red Olympic Peninsula. On the west side of (Chamaecyparis lawsoniana), western alder and Sitka alder (Alnus sinuata) the Olympic Peninsula, it grows on the white (Pinus monticola), and red- toward the north. Black cottonwood extensive coastal plain and seaward wood (). Shore ( trichocarpa) is an associate mountain slopes. The range narrows pine ( var. contorta) and throughout the range. farther south along the Washington and western redcedar () are Oregon coast, but extends inland for also associates that extend into several miles along the larger rivers. In southeast Alaska. Toward the north, Description and Growth northern California, it is discontinuous conifer associates also include Alaska- and extends south to Mendocino cedar (Chamaecyparis nootkatensis), Sitka spruce is a vigorous, fast-growing County. mountain hemlock ( mertensiana), tree usually dominant in the forest and subalpine fir (Abies lasiocarpa)- canopy. It is an impressive, tall, trees that are usually found only at straight tree with an evenly tapering Sitka spruce occasionally forms pure higher elevations toward the south. trunk. Mature trees often develop stands, but is commonly associated White spruce () is also enlarged, swollen, and buttressed bases with western hemlock (Tsuga associated with Sitka spruce in Alaska, and open conical crowns (fig. 2). 3 An American Wood

Figure 3–Foliage, cones, and of Sitka F-70501 spruce. Note the thin bark as shown in the chopped-out section. 4 An American Wood

Cones of Sitka spruce are usually 2 to Oregon, Washington, and southern because of demand in the aircraft in- 3-1/2 inches long, cylindrical, and light British Columbia and has been the most dustry. After the war, production brown (fig. 3). At maturity, scales are serious deterrent to management of declined to less than 80 million board thin, rounded, and papery, with ir- Sitka spruce in the southern part of its feet until World War II, when it ex- regular notches or teeth. Needles are range. ceeded 400 million board feet. Since 5/8 to 1 inch long, sharp-pointed, flat- World War II, production has declined. tened, and thin, with two whitish bands Common Names on each side. They extend from all The Alaska that cut Sitka sides of twigs. Needles are somewhat Sitka spruce is named for Sitka Island spruce produce a small volume of stan- diamond-shaped in cross section. The (now known as Baranof Island) in dard lumber items for local markets. outer bark is dark purplish and brown, southeast Alaska where the species was Most of the logs, however, are cut into thin, scaly, and relatively smooth; the discovered and named by Europeans in cants (squared-off logs) for export; inner bark is white with brown spots. 1832. Sitka spruce is also known as more than 98 percent of these are ship- Good cone crops occur at 3- to 5-year coast spruce, tideland spruce, and ped to . The amount of sawn intervals in the southern part of the yellow spruce. timber exported from Alaska has range and at 5- to 8-year intervals in declined over the last decade (fig. 4). Alaska. Individual trees occasionally Related Commercial Species The export of round logs has increased, produce cones before 20 years of age, however, following the transfer of but cone bearing usually does not begin Sitka spruce is sometimes marketed Federal lands to private ownership as a until ages 20 to 40. with white spruce, true , and other result of the settlement of Alaska species and included in Native land claims. This is because Seedling survival is exceptionally good estimates of these resources. A natural Federal restrictions on the export of because moisture is almost always ade- hybrid between Sitka spruce and white round logs do not apply on privately quate and seedlings are somewhat spruce (Picea ×lutzii Little) occurs in owned land in Alaska. Only a small tolerant of shade. After the seedling the Skeena River Valley of British Col- volume of Sitka spruce is exported stage, however, trees require overhead umbia and on the Kenai Peninsula in from the Pacific Northwest. light for rapid growth. Alaska. The hybrid shows some resistance to the white pine weevil. Characteristics and Properties Height growths of Sitka spruce and Sitka spruce is also known to cross western hemlock are nearly equal dur- with Yezo spruce (), The sapwood of Sitka spruce is creamy ing their periods of most rapid growth, Serbian spruce (P. omorika), and white to light yellow and blends but spruce grows more rapidly in Engelmann spruce (P. engelmannii). gradually into the heartwood, which is diameter. Consequently, thinning mixed pinkish yellow to brown. Sapwood in stands of smaller trees tends to favor Supply mature trees may be 3 to 6 inches wide spruce. Spruce maintains height growth and wider in young trees. longer than hemlock and lives longer. The volume of Sitka spruce sawtimber Few hemlock live more than 500 years, on commercial forest land in the United The wood has a fine, uniform texture, but Sitka spruce may live to 700 or States is estimated at 71,341 million generally straight grain, no distinct 1 800 years. Very old spruce trees even- board feet (International /4-inch rule). taste or odor, and relatively few tually become dominant in old-growth Alaska contains 89 percent of this ducts. The annual rings are distinct, hemlock-spruce stands. The largest volume; Washington, Oregon, and with a band of lighter colored Sitka spruce on record is located near California, 11 percent.2 earlywood shading gradually into a nar- Seaside, Oreg. It is 16.7 feet in rower band of darker latewood. diameter, 216 feet tall, and has a crown spread of 93 feet. Mature trees Production on the in Alaska average 160 feet in height and 3 Annual production of Sitka spruce to 5 feet in diameter at breast height. lumber steadily increased to 165 million board feet by 1899. Production Blowdown probably causes the most reached an all-time maximum of 508 serious damage to Sitka spruce, but the million board feet during World War I species is also attacked by insects, disease organisms, and animals. The white pine weevil () 2LaBau, Vernon J.; Personal communication. causes the most serious damage in Anchorage, AK: Sciences Laboratory. 5 An American Wood

Sitka spruce makes excellent pulp because of its long, strong fibers and the ease with which it can be process- ed. The wood is readily reduced by the sulfite chemical process to yield a strong pulp. Its texture is not as fine as that of white spruce, but it bleaches easily, making it suitable for the manufacture of newspaper and high- grade printing and bond papers. It also produces high-grade chemical pulps used to make rayon and plastics. The wood can also be reduced by the sulfate process to yield a strong pulp suitable for high-grade kraft wrapping papers and fiberboards. When made into pulp by the groundwood (mechanical) process, it yields a pro- duct suitable for many uses, such as , low-grade papers, and ab- sorbent material. Principal Uses

Major uses are for lumber and , especially in Alaska, where 89 percent of the Sitka spruce in the United States grows.

The high strength-to-weight ratio and Figure 4–Sitka spruce lumber exported from Alaska ports, 1969-80. resonant qualities of clear lumber are attributes that have traditionally made Sitka spruce wood valuable for spe- Sitka spruce wood is classed as preservatives under pressure, but can cialty uses. Today, these uses include moderate in weight, stiffness, hardness, be treated by a water-diffusion process. sounding boards for high-quality resistance to shock, shrinkage, bending, Thin panels of slow-growth Sitka , faces, ladders, and com- ponents of experimental light aircraft. and compressive strength. It ranks high spruce are highly resonant, making Other products are oars, planking, in strength on a weight basis. The them desirable for sounding average specific gravity is 0.37, based boards. masts, and spars for boats and turbine on green volume and ovendry weight. blades for -energy conversion The average density of air-dry wood systems. (12 percent moisture content) is 28 pounds per cubic foot. Wood from young, managed stands generally lacks the knot-free, slow- The availability of Sitka spruce in growth characteristics of old-growth large, clear, straight-grained pieces and trees. Experience from the United its high strength-weight ratio accounted Kingdom, where Sitka spruce has been for its early demand for use in aircraft. extensively planted, shows that the wood from young trees is suitable for The wood is not difficult to kiln-dry many construction purposes, but is and can be worked easily if it is free of often unsuitable for joinery. Machining knots. Sitka spruce has low resistance trials have shown that sharp cutting to decay; and when long life is re- edges are needed to produce a good quired, it should not be used untreated. planed finish, but the numerous hard It is resistant to impregnation with knots damage cutters rapidly. An American Wood

Revised February 1984

U.S. GOVERNMENT PRINTING OFFICE : 1984 O - 415-844 (Item 4) 7