Picea sitchensis

Picea sitchensis, Sitka spruce, is a large coniferous tree in the Pinaceae (pine family) that is the largest of the world's spruces and is one of the most prominent forest trees in stands along the northwest coast of North America. Also known as tideland spruce, coast spruce, and yellow spruce, this coastal species is seldom found far from tidewater, where moist maritime air and summer fogs help to maintain humid conditions necessary for growth. Throughout most of its range from northern California to Alaska, Sitka spruce is associated with western hemlock (Tsuga heterophylla) in dense stands where growth rates are among the highest in North America. It is a valuable commercial timber species for lumber, pulp, and various specialty products, and is the State Tree of Alaska.

Sitka spruce grows in a narrow strip along the north Pacific coast from latitude 61° N. in southcentral Alaska to 39° N. in northern California. The most extensive portion of the range in both width and elevation is in southeast Alaska and northern British Columbia, where the east-west range extends for about 210 km (130 mi) to include a narrow mainland strip and the many islands of the Alexander Archipelago in Alaska and the Queen Charlotte Islands in British Columbia. In Washington, the range includes a narrow mainland strip along the Strait of Georgia, around Puget Sound, up valleys to the east, and on the Olympic Peninsula. On the west side of the Olympic Peninsula, the range broadens to include the extensive coastal plain and seaward mountain slopes. It narrows southward along the Washington and Oregon coast but extends inland for several kilometers along the major rivers. In northern California, the range is more attenuated and becomes discontinuous. A disjunct population in Mendocino County, CA, marks the southern limit of the range.

Sitka spruce usually grows in mixed stands, less often in pure stands. Pure stands usually occur in early successional situations and as tidewater stands influenced by salt spray. Sitka spruce is commonly associated with western hemlock throughout most of its range. Toward the south, other conifer associates include Douglas-fir (Pseudotsuga menziesii), Port-Orford-cedar (Chamaecyparis lawsoniana), western white pine (Pinus monticola), and redwood (Sequoia sempervirens).

Sitka spruce is commercially harvested as pulpwood and for lumbers. High strength-to-weight ratio and resonant qualities of clear lumber are attributes that have traditionally made Sitka spruce wood valuable for specialty uses, such as sounding boards for high-quality pianos; guitar faces; ladders; construction components of experimental light aircraft; oars, planking, masts, and spars for custom-made or traditional boats; and turbine blades for wind energy conversion systems.

General: Spruce Family (Pinaceae). Sitka spruce is a large, native, evergreen tree that can grow up to two hundred feet in height. The needles are yellowish-green to bluish-green, stiff, very sharp, 1 to 1½ inches long, with white lines of stomata on the upper surface (Pojar & MacKinnon 1994). The cones are one to four inches long, hanging down, with very thin scales, rounded, and irregularly toothed. The bark is gray and smooth on small trunks, becoming dark purplish-brown on older trunks.

Distribution: Sitka spruce is native to the Pacific Coast region from Alaska, to western British Columbia, Washington, Oregon, and northwestern California. For current distribution, please consult the Plant profile page for this species on the PLANTS Web site.

sitka spur, coast west spruce, coast spruce, tideland spruce, yellow spruce, western spruce, silver spruce, menzies’ spruce

More info for the term: natural

Sitka spruce's natural range is a narrow strip of land along the
northern Pacific coast from south-central Alaska to northern California.
Its widest distribution (130 miles [210 km] inland) occurs in
southwestern Alaska and northern British Columbia. Its southern
boundary is defined by a disjunct population in Mendocino County,
California [23,24].

Sitka spruce has been extensively introduced into the British Isles
[35,57].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border

AK CA HI OR WA BC YT

Picea sitchensis (Bong.) Carrière:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Picea sitchensis is often found on moist well-drained sites such as alluvial floodplains, marine terraces, and headlands (Pojar & MacKinnon 1994). This species prefers full sun and is intolerant of shade and atmospheric pollution. Sitka spruce grows in pure stands, more often mixed with western hemlock, Douglas fir, western redcedar, yellow cedar, grand fir, red alder, and black cottonwood (Farrar 1995).

Trees to 80m; trunk to 5m diam.; crown narrowly conic. Bark grayish brown to orange-brown. Branches somewhat drooping; twigs not pendent, rather stout, pinkish brown, glabrous. Buds reddish brown, 5--10mm, apex rounded. Leaves (1.2--)1.5--2.5(--3)cm, flattened or broadly triangular in cross section (abaxial surface rounded or slightly angular), rather rigid, blue-green to light yellow-green, abaxial surface darker green with stomatal bands very narrow or absent, adaxial surface glaucous with conspicuous stomatal bands separated by ridge, apex sharp-pointed. Seed cones 5--9(--10)cm; scales variable, elliptic to narrowly diamond-shaped, 15--22 ´ 12--16mm, rather rigid, margin at apex erose, apex extending 4--8mm beyond seed-wing impression. 2 n =24.

Tree, Evergreen, Monoecious, Habit erect, Trees without or rarely having knees, Tree with bark rough or scaly, Young shoots 3-dimensional, Buds resinous, Buds not resinous, Leaves needle-like, Leaves alternate, Needle-like leaf margins entire (use magnification), Leaf apex acute, Leaves < 5 cm long, Leaves < 10 cm long, Leaves yellow-green above, Leaves yellow-green below, Leaves blue-green, Leaves not blue-green, Needle-like leaves flat, Needle-like leaves triangular, Needle-like leaves not twisted, Needle-like leaf habit erect, Needle-like leaf habit drooping, Needle-like leaves per fascicle mostly 1, Needle-like leaf sheath early deciduous, Needle-like leaf sheath persistent, Twigs glabrous, Twigs viscid, Twigs not viscid, Twigs with peg-like projections or large fascicles after needles fall, Berry-like cones orange, Woody seed cones > 5 cm long, Bracts of seed cone included, Seeds red, Seeds brown, Seeds winged, Seeds unequally winged, Seed wings prominent, Seed wings equal to or broader than body.

More info for the terms: monoecious, tree

Sitka spruce is a native, long-lived (greater than 800 years),
evergreen, monoecious tree [24,55]. Female strobili are produced at the
ends of primary branches near the top, while the male strobili are
positioned lower in the tree on secondary branches [24].

Sitka spruce is the world's largest spruce. It can obtain heights of
greater than 210 feet (65 m) with a d.b.h. of 16 feet (5 m) on better
sites [24]. The base of the bole is buttressed [55]. When forest grown
the bole is long and free of lower limbs [23].

The root system of Sitka spruce is shallow and platelike with long
lateral roots with few branchings. On deep well-drained soils the root
system may reach depths of 6.5 feet (2 m), especially on alluvial soils.
Root grafting often occurs between roots of the same tree and adjacent
trees [22,24].

Pinus sitchensis Bongard, Mém. Acad. Imp. Sci. Saint-Pétersbourg, Sér. 6, Sci. Math. 2: 164. 1832 (Aug.); Abies falcata Rafinesque; A. menziesii (Douglas ex D. Don) Lindley 1835, not Mirbel 1825; Picea falcata (Rafinesque) Suringar; P. menziesii (Douglas ex D. Don) Carrière; Pinus menziesii Douglas ex D. Don

Sitka spruce occurs in the hypermaritime to maritime cool mesothermal
climates [32,33]. It occurs from shoreline to timberline in the
northern portion of its range but is restricted to shoreline in the
southern portion of its range [6]. Sitka spruce grows best on sites
with deep, moist, well-drained soils [22]. It can tolerate the salty
ocean spray of seaside dunes, headlands, and beaches, and the brackish
water of bogs [34]. Stika spruce is limited to areas of high annual
precipitation with cool, moist summers [16,23].

Soil: Sitka spruce has a stong affinity for soils high in calcium,
magnesium, and phosphorus in the soil orders Entisols, Spodosols,
Inceptisols, and Histosols. These soils are usually acidic with pH
typically ranging from 4.0 to 5.7 [24].

Elevation: Sitka spruce grows from sea level to timberline in Alaska (0
to 3,900 feet (0-1,189 m)) [55] with elevational limitations of 2,000
feet (600 m) in Washington and 1,500 feet (450 m) in Oregon and
California [5].

Associates: In addition to those listed under Distribution and
Occurrence, Stika spruce's overstory associates include mountain hemlock
(Tsuga mertensiana), Alaska-cedar (Chamaecyparis nootkatensis),
lodgepole pine (Pinus contorta), and western white pine (P. monticola)
[24].

Understory associates include western swordfern (Polystichum munitum),
false lily-of-the-valley (Maianthemum dilatatum), stream violet (Viola
glabella), evergreen violet (V. sempervirens), red huckleberry
(Vaccinium parvifolium), devils club (Oplopanax horridum), salmonberry
(Rubus spectablis), and thimbleberry (R. parviflorus) [24].

More info for the terms: association, natural

Sitka spruce is listed as a dominant overstory species in the following
published classifications:

Natural vegetation of Oregon and Washington [16].
Plant association and management guide: Sinslaw National Forest [27].
Preliminary classification of forest vegetation of the Kenai
Peninsula, Alaska [46].

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES20 Douglas-fir
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce
FRES27 Redwood

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

221 Red alder
222 Black cottonwood - willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock - Sitka spruce
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock
231 Port-Orford-cedar
232 Redwood

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K006 Redwood forest
K029 California mixed evergreen forest

Sitka spruce grows on Entisols, Spodosols, Inceptisols, and Histosols,  on soils derived from a wide variety of parent material. The species  requires relatively high amounts of available calcium, magnesium, and  phosphorus, and grows best where soils are derived from rocks rich in  calcium and magnesium (19). Best development is on deep, moist,  well-aerated soils. Drainage is an important factor, and growth is poor on  swampy sites. Sitka spruce commonly occupies alluvial soils along streams,  sandy or coarse-textured soils, or soils having a thick accumulation of  organic material. Soils are usually acidic, and pH values of 4.0 to 5.7  are typical. Spruce is an early pioneer on immature soils recently exposed  by glacial retreat or uplift from the sea. It is more tolerant of ocean  spray than are associated trees and often occupies a prominent position on  exposed headlands and beaches along the outer coast (2). In Oregon and  Washington, spruce follows lodgepole pine (Pinus contorta) in  succession on coastal sand dunes as they become stabilized by vegetation.  On highly disturbed sites, it frequently becomes established concurrently  with red alder (Alnus rubra) or Sitka alder (A. sinuata), gradually  succeeding the alder as stands are eventually overtopped.

    Sitka spruce grows from sea level to treeline in Alaska, at elevations  ranging from 910 m (3,000 ft) in southeast Alaska to 300 m (1,000 ft) in  Prince William Sound. High mountains of the coast ranges lie close to the  sea, forming a barrier to moist, onshore winds and providing abundant  moisture during the growing season. Spruce is limited in elevation by the  short growing season at treeline. South of northern British Columbia,  spruce is restricted to low elevations near the sea where moist maritime  air and fog help provide moisture during summer. For the most part, high  mountains that otherwise might offer suitable habitat lie farther inland  where more continental conditions of summer drought and warmer  temperatures are unsuitable for growth. Exceptions are on the Olympic  Peninsula and in valleys in the Cascade Range off Puget Sound in  Washington, and on isolated peaks in Oregon. On the Olympic Peninsula,  Sitka spruce rarely grows above 610 rn (2,000 ft) in elevation (1).

Sitka spruce is restricted to an area of maritime climate with abundant  moisture throughout the year, relatively mild winters, and cool summers.  Summer temperatures decrease northward and lack the extremes found in more  continental locations. In terms of growing degree days, annual heat sums  (based on a threshold of 5° C or 41° F) range from 2511° C  (4,552° F) at Brookings, OR (lat. 41° 03' N.) to 851° C  (1,564° F) at Cordova, AK (lat. 60° 30' N.) (8). The number of  frost-free days varies locally but generally declines northward; averages  range from about 294 days at Brookings, OR, to 111 days at Cordova, AK

    Annual precipitation varies within the range of Sitka spruce and is  influenced greatly by local topography. Annual precipitation of 2950 mm  (116 in) at Forks, WA, and 5615 mm (221 in) at Little Port Walter, AK,  contrasts with 635 mm (25 in) at Anacortes, WA, and 660 mm (26 in) at  Skagway, AK Summer precipitation is greater toward the north, where light  drizzle and fog are frequent. At Cordova, AK, from June to September, at  least a trace of precipitation occurs during 22 to 24 days each month. In  contrast, at Otis, OR, a trace or more of precipitation occurs on only 8  to 15 days each month. Toward the south, fog and moist maritime air are  important in maintaining moisture conditions needed for growth; most  winter precipitation is in the form of rain. Depth of snowfall increases  northward. Average annual snowfall at sea level is 1 em (0.5 in) at  Brookings, OR; 58 cm (23 in) at Quatsino, BC; and 340 cm (134 in) at  Cordova, AK

Pacific coastal forests; 0--900m; B.C.; Alaska, Calif., Oreg., Wash.

Systems

• Terrestrial

Propagation by Seed: Picea sitchensis seed requires no pretreatment if the seed is sown fresh, however a period of cold unifies and hastens germination (Dirr & Heuser 1987). Sow stored seeds as early in the year as possible. Preferably sow the seeds in a position in light shade. Seeds should be stored in a cool place and should not be allowed to dry out. Put seedlings into individual pots when they are large enough to handle and grow them in the greenhouse for the first winter. They can be planted into their permanent positions in early summer of the following year.

Propagation by Cuttings: The cuttings, five to ten centimeters long, are cut in June with a heel of older wood, treated with 3000 ppm IBA-talc, and placed in sand without removal of the needles (Dirr & Heuser 1987). After rooting, the cuttings have one to two roots that should be pruned to stimulate lateral root development before transplanting to flats. Staking is also required to develop a symmetrical plant form (Ibid.).

Foodplant / gall
hypophyllous Adelges cooleyi causes gall of live, yellowing shoot tip of Picea sitchensis

In Great Britain and/or Ireland:
Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Amanita muscaria var. aureola is ectomycorrhizal with live root of Picea sitchensis
Remarks: Other: uncertain

Foodplant / pathogen
Armillaria mellea s.l. infects and damages Picea sitchensis

Foodplant / pathogen
pycnidium of Ascochyta coelomycetous anamorph of Ascochyta piniperda infects and damages defoliated shoot of Picea sitchensis

Foodplant / parasite
hypophyllous telium of Chrysomyxa abietis parasitises live needle of Picea sitchensis
Remarks: season: 3-5

Foodplant / parasite
amphigenous aecium of Chrysomyxa ledi var. rhododendri parasitises live needle of Picea sitchensis
Remarks: season: 7-9
Other: unusual host/prey

Foodplant / sap sucker
Cinara piceae sucks sap of Picea sitchensis

Foodplant / saprobe
fruitbody of Coniophora prasinoides is saprobic on decayed bark of Picea sitchensis

Foodplant / false gall
crowded pseudothecium of Cucurbitaria piceae causes swelling of characteristically twisted, swollen bud of Picea sitchensis

Foodplant / saprobe
fruitbody of Diplomitoporus lindbladii is saprobic on fallen, dead log (large) of Picea sitchensis

Foodplant / sap sucker
Elatobium abietinum sucks sap of live, yellowed then shed leaf of Picea sitchensis
Remarks: season: (1-)3-5(-12)
Other: major host/prey

Foodplant / saprobe
effuse colony of Endophragmiella dematiaceous anamorph of Endophragmiella resinae is saprobic on old wound of Picea sitchensis
Remarks: season: 9

Foodplant / saprobe
fruitbody of Fomitopsis pinicola is saprobic on dead log (large) of Picea sitchensis

Foodplant / saprobe
fruitbody of Globulicium hiemale is saprobic on decayed wood of Picea sitchensis

Plant / associate
fruitbody of Hebeloma populinum is associated with Picea sitchensis

Foodplant / saprobe
hysterothecium of Lophium mytilinum is saprobic on dead, old, decorticate log of Picea sitchensis
Remarks: season: 7-8
Other: minor host/prey

Foodplant / saprobe
apothecium of Lophodermium piceae is saprobic on dead, attached needle of Picea sitchensis
Remarks: season: 5

Foodplant / saprobe
erumpent apothecium of Micraspis tetraspora is saprobic on dead, decorticated wood of Picea sitchensis
Remarks: season: 10-11

Foodplant / pathogen
amphigenous colony of Mycocentrospora anamorph of Mycocentrospora acerina infects and damages live leaf of Picea sitchensis

Foodplant / saprobe
erumpent stroma of Nectria fuckeliana is saprobic on dead twig of Picea sitchensis
Remarks: season: 3-8

Foodplant / sap sucker
Pachypappa sucks sap of live root of Picea sitchensis

Foodplant / sap sucker
Pachypappella sucks sap of live root of Picea sitchensis

Foodplant / pathogen
fruitbody of Phaeolus schweinitzii infects and damages live root of Picea sitchensis

Foodplant / gall
gallicola nymph of Pineus similis causes gall of Picea sitchensis

Foodplant / saprobe
erumpent apothecium of Pseudophacidium piceae is saprobic on dead, old but not decayed log of Picea sitchensis
Remarks: season: 5

Foodplant / saprobe
superficial, clustered, hypophyllous pycnidium of Rhizosphaera coelomycetous anamorph of Rhizosphaera kalkhoffii is saprobic on dead needle of Picea sitchensis
Remarks: season: late winter to early spring

Foodplant / saprobe
erumpent, shortly stalked apothecium of Tryblidiopsis pinastri is saprobic on dead, attached twig of Picea sitchensis
Remarks: season: 5-7

Foodplant / saprobe
Tubulicium vermiferum is saprobic on dead wood of debris of Picea sitchensis
Other: unusual host/prey

Sitka spruce is commonly associated with western hemlock throughout most  of its range. Toward the south, other conifer associates include  Douglas-fir (Pseudotsuga menziesii), Port-Orford-cedar (Chamaecyparis  lawsoniana), western white pine (Pinus monticola), and redwood  (Sequoia sempervirens). Shore pine (P. contorta var. contorta)  and western redcedar (Thuja plicata) are also associates that  extend into southeast Alaska. Toward the north, conifer associates also  include Alaska-cedar (Chamaecyparis nootkatensis), mountain  hemlock (Tsuga mertensiana), and subalpine fir (Abies  lasiocarpa)-trees that are usually found only at higher elevations  toward the south. In central and northern British Columbia and Alaska,  however, these species are found with Sitka spruce from sea level to  timberline. White spruce (Picea glauca) is also associated with  Sitka spruce in Alaska, and hybrids occur. The most important hardwood  associates are red alder and bigleaf maple (Acer macrophyllum) in  the south and red alder and Sitka alder toward the north. Black cottonwood  (Populus trichocarpa) is an associate throughout the range.

    Stands stocked with at least 80 percent Sitka spruce are identified as  the forest cover type Sitka Spruce (Society of American Foresters Type  223) (6). Sitka spruce is also a component of 10 other forest cover types:

    221 Red Alder 
222 Black Cottonwood-Willow 
224 Western Hemlock 
225 Western Hemlock-Sitka Spruce 
227 Western Redcedar-Western Hemlock 
228 Western Redcedar 
229 Pacific Douglas-Fir 
230 Douglas-Fir-Western Hemlock 
231 Port-Orford-Cedar 
232 Redwood

    Sitka spruce usually grows in mixed stands, less often in pure stands.  Pure stands usually occur in early successional situations and as  tidewater stands influenced by salt spray. The most extensive pure stands  are found on the Kodiak-Afognak Archipelago at the extreme west extension  of the range. Sitka spruce is the only conifer present on this group of  islands. A relatively recent invader there, spruce is expanding its range  to the southwest, invading a tundra complex at the rate of about 1.6 km (1  mi) per century (14).

    In Oregon and Washington, common understory species associated with  Sitka spruce include swordfern (Polystichum munitum), Oregon  oxalis (Oxalis oregana), false lily-of-the-valley (Maianthemum  dilatatum), western springbeauty (Montia sibirica), three-leaved  coolwort (Tiarella trifoliata), evergreen violet (Viola  sempervirens), stream violet (V. glabella), Smith fairybells  (Disporum smithii), red huckleberry (Vaccinium parvifolium),  and rustyleaf menziesia (Menziesia ferruginea). On drier  sites, salal (Gaultheria shallon), Pacific rhododendron (Rhododendron  macrophyllum), and evergreen huckleberry (Vaccinium ovatum) are  common. On wetter forest sites, the previously mentioned species are  found, along with devilsclub (Oplopanax horridum), ladyfern (Athyrium  filix-femina), deerfern (Blechnum spicant), mountain woodfern  (Dryopteris austriaca), and Pacific red elder (Sambucus  callicarpa) (11).

    In Alaska, the more common understory plants include devilsclub,  skunkcabbage (Lysichitum americanum), ovalleaf huckleberry (Vaccinium  ovalifolium), red huckleberry, Alaska blueberry (V. alaskaense),  rustyleaf menziesia, salmonberry (Rubus spectabilis), five-leaf  bramble (R. pedatus), thimbleberry (R. parviflorus), bunchberry  (Cornus canadensis), stink currant (Ribes bracteosum), and  trailing black currant (R. laxiflorum) (32). Cryptogams are  abundant throughout the range of Sitka spruce. The Olympic Peninsula is  especially noted for mosses, many of which occur as epiphytes on living  trees.

    In Oregon and Washington within the Sitka spruce forest zone, important  plant communities include Tsuga heterophylla-Picea  sitchensis/Gaultheria shallon/Blechnum spicant, Tsuga-Picea/Oplopanax  horridum/Athyrium filix-femina, or Tsuga-Picea/Polystichum  munitum-Oxalis oregana (11). Similar communities can be found in  southern British Columbia within the "fog western hemlock/Sitka  spruce subzone" (23). In Alaska, some of the more common communities  include Picea sitchensis/Oplopanax horridum-Rubus spectabilis/Cornus  canadensis, Picea sitchensis-Tsuga heterophylla/Lysichiton  americanum/Sphagnum spp., and Tsuga heterophylla-Picea  sitchensis-(Thuja plicata)/Vaccinium ovalifolium-V.  alaskaense/Rhytidiadelphus loreus (32).

Blowdown is probably the most serious damaging  agent of Sitka spruce, but the species is attacked by a number of  pests-insects, disease organisms, and animals. In general, problems tend  to be more severe toward the south. The white pine weevil (Pissodes  strobi) is the most serious insect pest in Oregon, Washington, and  southern British Columbia; weevil damage has been the most serious  deterrent to management of Sitka spruce in the southern part of its range.  Damage is most severe on young trees 3 to 6 in (10 to 20 ft) tall. The  weevil is not a problem on the Queen Charlotte Islands or in Alaska,  possibly because there is insufficient summer heat to allow its  development (22). The spruce aphid (Elatobium abietinum) feeds on  Sitka spruce from California to Alaska and is a pest of ornamental trees.  Epidemics are sporadic and short lived. A root-collar weevil (Steremnius  carinatus) girdles l- and 2-year-old seedlings, causing some losses.  The spruce beetle (Dendroctonus rufipennis) periodically damages  stands throughout the range and is a major pest of spruce in British  Columbia. In addition, damage from a number of defoliators and other  insects is common (13).

    Sitka spruce is highly susceptible to decay when injured (18). In the  past, most emphasis has been on studies of decay in old-growth stands, but  currently interest is shifting to young, managed stands. Some of the  organisms causing decay in old growth (for example, Heterobasidion  annosum and Armillaria mellea) can also cause root rot in  young stands. Heterobasidion annosum infects freshly cut stump  surfaces, and in Europe the tendency for plantation-grown Sitka spruce to  develop H. annosum butt rot is well known.

    Foliage and stem diseases are usually of minor importance. Several rusts  cause occasional light to moderate defoliation, witches' brooms, or loss  of cones. Seed and seedling diseases are probably most important in  production of containerized seedlings in greenhouses.

    Sitka spruce is damaged at various locations by animals such as elk,  bear, deer, porcupines, rabbits, hares, and squirrels. In general, these  problems are more serious in the southern part of the range. Deer are  generally more troublesome in the southern part, porcupines in the  northern part (25). Spruce is often less damaged than its associates.

    Few growth abnormalities have been reported, although large tumorlike  growths on stems have been reported in Washington, and they occur in  Alaska as well. The causal agent is not known.

More info for the term: fire exclusion

Arguments for and against slash burning in spruce forests recur
throughout the literature. The strategy chosen will yield different
results, depending on latitude.

In the northern portion of Sitka spruce's range broadcast burning will
favor Sitka spruce over western hemlock, but unless Sitka spruce is
planted, seedling establishment will be delayed until the next seed crop
[14,26,48,49]. Ruth and Harris [49] list the advantages of slash
burning as follows:

(1) Reduces fire hazard
(2) Destroys advance regeneration *
(3) Changes timber type

* This can have both positive and negative ramifications. It reduces
competition with western hemlock, but growth of Sitka spruce seedlings
in one study was reduced [14].

In the southern portion of its range broadcast burning will favor the
establishment of Douglas-fir (Pseudotsuga menziesii) mixed forest, while
long-term fire exclusion will result in loss of Douglas-fir from the
overstory. This is advantageous due to the increased stumpage value of
Douglas-fir and the negative impacts of the spruce weevil [44,49].

In the coastal area of Alaska, broadcast burning has been recommended to
reduce the negative aesthetic value of large quantities of slash from
clearcut old-growth Sitka spruce forests [53].

However, removal of the slash by burning in Sitka spruce forests is not
required because of the to rapid decay in that moist environment [48].
Burning is not recommended on steep slopes and where water quality may
be degraded [48,53].

More info for the term: tree

Sitka spruce will invade a burned site via wind-dispersed seed from
adjacent unburned forests [49]. Wind-dispersed seed travels 33 to 880
yards (30-792 m) from the parent tree [24].

More info for the term: tree

The immediate effect of a cool to hot fire is damage to the cambium
layer, usually resulting in death of the tree [5,8].

More info for the term: fire regime

Fire is not an important factor in the ecolgy of Sitka spruce [1]. Its
thin bark and a shallow root system make it very susceptible to fire
damage [5,8]. Sitka spruce forests have a fire regime of long-interval
(150 to 350+ years) severe crown or surface fires which result in total
stand replacement [44].

More info on this topic.

More info for the term: climax

Sitka spruce is a shade-intolerant species [33] that is both a pioneer
and a climax species [22]. Sitka spuce acts as an early pioneer on the
undeveloped soils of landslides, sand dunes, uplifted beaches, and
deglaciated terrain; it is a climax species in the coastal forests [22].

More info for the terms: epigeal, layering

Sitka spruce reproduces both sexually and asexually. Sexual maturity
varies from 20 to 40 years. Dispersal of seeds is moisture dependent;
when the ripe cones dry the seed is dispersed, and when the cones become
wet again they close. To avoid loss of seed, cones should be collected
soon after ripening [50]. The seeds are small with a mean of 210,000
cleaned seeds per pound (467,000/kg) [24]. The germination rate is 54
percent, but this can be raised to 66 percent by moistening the
germination medium with a 0.2 percent potassium nitrate (KNO3) solution
[50].

Germination is epigeal. Sitka spruce seed will germinate on almost any
substate, although mineral soil or a mixture of mineral soil and organic
soil are considered the best seedbeds [24]. The "nurse log syndrome"
has a key role in the regeneration of Sitka spruce in its wetter
environs [12,15,20]. Germination and seedling survival are greater on
rotting logs then on the forest floor. In a germination study less than
1 percent of the seeds in a moss mat germinated, and of these 38 percent
were killed within a month by fungi [21]. Nurse log syndrome results in
a "colonnade" where there are several trees in a row with the roots
supporting the bole in mid-air after the nurse log has rotted away [5].

Seedling establishment and growth can be enhanced with the inoculation of
the mycorrhizal fungi, Thelephora terrestris [10,40].

Sitka spruce shows strong trends in hardiness and growth in relation to
geographic origination. These trends can be used to increase growth
rate, but they can also have adverse effects on survival [22,38].
Lester and others [38] provide information on seed sources, outplanting
results, hardiness, and growth rate trends.

Sitka spruce reproduces asexually by layering. This usually takes place
in moist areas or at timberline [22,24,31,55]. Cuttings from current
year's growth root more readily than older branches [24].

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Phanerophyte

More info for the term: tree

Tree

Secondary colonizer - offsite seed

Sitka spruce is more tolerant of shade  than Douglas-fir but less tolerant than hemlock. Depending on latitude,  Sitka spruce has been described as being in the tolerant and intermediate  shade-tolerant classes. Overall, it probably can most accurately be  classed as tolerant of shade. Since reproduction under mixed stands is  predominantly hemlock, there is a tendency for this more tolerant species  to eventually dominate the site. Few climax stands proceed to pure  hemlock, however; in time, small openings, usually caused by blowdowns,  develop, allowing reproduction of spruce. The combination of greater  stature, greater longevity, and occasional stand disturbance is enough to  assure a scattering of spruce in the overstory of most climax  hemlock-spruce stands.

    Sitka spruce is one of the few conifers that develop epicormic branches  along the stem. Production of these sprouts is related to light intensity,  and roadside trees often develop dense new foliage from base to crown.  Thinning stimulates epicormic branching and could decrease the quality of  the wood, although this is not a problem in production of pulp or  dimension lumber. In deep shade, lower limbs soon die, decay, and break  off, but the resinous branch stubs remain for many years.

Roots will grow where moisture, fertility,  aeration, and mechanical soil properties are favorable. Consequently,  there is great variability in root form-from flat platelike roots to deep,  narrow-spreading roots (12). Where soils are shallow, soil temperature and  fertility low, and water tables high, shallow rooting is by far the most  common form. Deeper rooting does occur, however, where soils have good  drainage and depth to water table. Rooting to depths of 2 m (6 ft) has  been reported (5).

    Sitka spruce commonly produces long lateral roots with few branches and  rapid elongation (20). Annual elongation rates of 42 to 167 cm (16 to 66  in) have been reported (3). Lateral roots up to 23 m (75 ft) in length  have been observed in Alaska (15). Root grafting occurs between roots of  the same tree and between adjacent trees. It is fairly common to find  living stumps sustained by root grafts from adjacent trees. Adventitious  roots develop on trees growing along streams where alluvium is deposited  by periodic flooding. Roots are vulnerable, however, to compaction and  lack of aeration. Spruce are frequently killed by permanent flooding  caused by beavers, and often valuable ornamental and roadside trees are  killed when landfill is deposited around them. Containerized nursery stock  has been successfully inoculated with the mycorrhizal fungi, Laccaria  laccata and Cenococcum geophilum (29).

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Flowering and seed dispersal dates for Sitka spruce in Alaska and Oregon
are as follows [22,50]:

Flowering Fruit Ripens Seed Dispersal

Alaska April to June late Aug. to mid-Sept. Starts in Oct

Oregon May Aug Oct. to Spring

Seed dispersal is moisture dependent; when the ripe cones dry dispersal
begins. The majority (73 percent) of seed are dispersed in the first 6
weeks; the remainder are released over the next year [22].

Asexual reproduction by layering occurs  under natural conditions and in plantations, but layering is most likely  to occur on very moist sites at the edges of bogs or near timberline.  Asexual propagation can be done by air-layering or rooting of stem  cuttings. Clones differ in their ability to root or graft, and clones that  graft easily do not necessarily root easily and vice versa. Cuttings from  shoots of the current year root more easily than cuttings from older  branches (15).

Under natural conditions, seed germinates  on almost any seedbed, but survival may be low. Germination is epigeal  (26). A mineral soil or mixed mineral and organic soil seedbed is usually  considered best for germination, especially under light shade, as long as  drainage is adequate and the soil provides sufficient nutrients for tree  growth. Fine-textured soils combined with a high water table are suitable  for germination but may be unsuitable for seedling establishment because  of frost heaving. Coarse-textured mineral soils in unshaded conditions may  dry out excessively but may improve after invasion by hair mosses that  bind the soil surface and provide shade. Organic seedbeds are suitable in  shade but are unsuitable in the open if subject to severe moisture  fluctuations. On alluvial sites having high water tables and subject to  frequent flooding, where competition from brush is severe, rotten wood may  be the only suitable seedbed.

Seeds of Sitka spruce are  small, averaging 463,000/kg (210,000/lb) (26). Seeds ripen in southeast  Alaska during late August or early September, and dispersal usually begins  in October. Cones open during dry weather, release seed, and reclose  during wet weather. One study showed that 73 percent of the seed was  released within 6 weeks of the first dispersal date, and the remainder was  released over 1 year (15). Good crops occur at 3- to 5-year intervals in  the southern part of the range and at 5- to 8-year intervals in Alaska.  Cone and seed production in seed orchards can be increased by treating  trees with gibberellin (31). Dispersal distance depends on several  factors, including height and location of the seed source, local  topography, and wind conditions. Reported dispersal distances range from  0.8 km (0.5 mi) when a seed source was on high ground, to 30 m (100 ft)  when seed was released from the edge of a clearcut area (15).

Individual Sitka spruce may occasionally  produce cones before 20 years of age, but cone bearing in stands usually  does not begin until ages 20 to 40 (24). Sitka spruce is monoecious;  female strobili (cones) are usually produced at the ends of primary  branches near tops of trees; male strobili are usually produced at the  ends of secondary branches lower in trees. Both may be on the same branch.  Reproductive buds are initiated in early summer of the year preceding  pollination and seed ripening, and heavy cone crops have been explained in  terms of early summer drought the preceding year. Cones ripen in the year  they were pollinated. Pollen is shed from the last week in April in the  southern portion of the natural range through early June in the extreme  northwest part of the range. Time of flowering is mainly related to  temperature.

Height growth is slow for the first few years  but increases rapidly thereafter. On average sites in southeast Alaska,  trees can be expected to reach about 27 m (90 ft) in height within 50  years after attaining breast height (7). Average site index at elevations  near sea level varies inversely with latitude, declining from 48 m (158  ft) at base age 100 years in Lincoln County, OR, to 33 m (108 ft) in  southeast Alaska, at the rate of about 1 m (3 ft) per degree of latitude  (8). Observations within the natural range of spruce show that growth rate  also declines with increasing elevation.

    Height growth of Sitka spruce and western hemlock are nearly equal  during the period of most rapid growth, but spruce grows more rapidly in  diameter. Consequently, thinning from below tends to favor spruce. Spruce  continues to maintain height growth longer than hemlock and lives longer.  Few hemlock live more than 500 years; Sitka spruce may live to 700 or 800  years. Very old spruces eventually assume a dominant position in  old-growth hemlock-spruce stands.

    Sitka spruce trees often attain great size. In Alaska, mature trees near  sea level may exceed 61 m (200 ft) in height and 3 m (10 ft) in d.b.h. In  Oregon, a tree 87 m (286 ft) tall was reported (24). The largest tree on  record is located near Seaside, OR. It is 5.1 m (16.7 ft) in d.b.h. and  65.8 m (216 ft) tall and has a crown spread of 28 m (93 ft) (17).

    Stands in which Sitka spruce is a major component tend to be dense, and  yields are high (21,30). Stand volumes can be impressive. One plot in a  147-year-old hemlock-spruce stand in coastal Oregon contained, on an area  basis, 188 spruce and 32 hemlock/ha (76 spruce and 13 hemlock/acre). Total  volume was 2380 m³/ha (34,000 ft³/acre). Spruce averaged 64 m  (210 ft) in height and 86 cm (34 in) in d.b.h., and hemlock averaged 44 m  (144 ft) in height and 46 cm (18 in) in d.b.h (24).

In addition to the clinal latitudinal difference in growth rate, cone  characteristics such as size, length-to-width ratio, angle of sterigma,  and phylotaxy also vary with latitude (4).

    Variation in wood characteristics has been reported by provenance,  region, site, and individual trees. Although no comprehensive heritability  studies have been completed, Sitka spruce shows considerable variation in  wood density, tracheid length, and grain angle. Improvement in these  characteristics through breeding appears feasible. Selection for vigor  tends to favor trees of lower-than-average specific gravity but has no  effect on tracheid length (15).

    Provenance studies show that- at a given planting site- northern,  inland, and high-elevation sources are the first and the most variable in  breaking dormancy. Dormancy appears to be influenced by photoperiod, and  northern provenances are the first to enter dormancy. Total seasonal  height growth is positively correlated with the time interval between  flushing and dormancy. When moved north, introduced southern sources make  better height growth, but they may be subject to frost damage if moved too  far or planted on exposed sites. Once dormant, Sitka spruce is able to  endure very low temperatures without damage. Sitka spruce from northern  provenances may be more resistant to freezing than those from southern  provenances. Dormant leaves from a Bellingham, WA, source withstood  temperatures to -30° C (-22° F), whereas a Juneau, AK, source  withstood temperatures to -40° C (-40° F). Twigs of the two  sources withstood temperatures to -40° C and -60° C (-40° F  and -76° F), respectively (27).

    Only limited data are available on genetic variation between individual  trees. Assessment of first-year characteristics of progeny from a diallel  cross among six trees showed that characters affecting tree form were  inherited in a predominantly additive fashion; characters reflecting tree  vigor were under "additive, dominance, and maternal control"  (28). Self-pollinated progeny showed growth depression caused by  inbreeding (28).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 9
Species With Barcodes: 1

Year Assessed

• Needs updating

Assessor/s

Reviewer/s

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Please consult the Plants Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.

More info for the terms: shrub, tree

Sitka spruce, as one of the most important timber species and components
of old-growth habitat, has recently been the center of many management
concerns. Proposals for changes in timber harvest areas and methods
have been explored by Nyberg and others [43] and Schoen and Kirchhoff
[51]. They provide in-depth information and management alternatives.

Wildlife habitat: Even-aged management of the species results in
reduced habitat for the black-tailed deer. Shrub fields created after
clearcutting are of limited use to deer in the winter. The depth of
snow accumulation is greater, and snow persists longer in the clearcuts,
reducing the time available for browsing. The forage in clearcuts is
less digestible than that grown in the shade of the preharvest stands.
Also, the large amount of slash resulting from clearcutting old-growth
Sitka spruce impedes movement of large ungulates, especially during
winter migration. Lastly, once the regeneration has reached canopy
closure (20 to 30 years), the understory production is greatly reduced
for at least the next 100 years, compared to old-growth stands with
their various stages of regeneration [19,25].

Alaback [2] studied ways to reduce the negative impact of clearcutting
on Sitka deer. Thinning the stands prior to canopy closure (less than
25 years) seems to be the best method for areas already cut. Thinning
to 12 x 12 feet (3.5 x 3.5 m) spacing results in the most diverse
vegetation. Once canopy closure has occurred (greater than 30 years),
uneven-aged management practices can result in the creation of gaps in
the canopy, which in turn will allow for a more diverse understory [3].

Damaging agents: Sitka spruce is susceptible to Sitka spruce weevil, or
white pine weevil (Pissodes strobi)), spruce aphid (Elatobium
abietinum), spruce beetle (Dendroctonus rufipennis), and root rot by
Armillaria millea and Heterobasidian annosum [24].

The Sitka spruce weevil has such a detrimental effect on Sitka spruce in
the lower portion of its range, from southern British Columbia to
northern California, that Sitka spruce is not actively managed for
regeneration there. The F1 generation of the hybrid, Lutz spuce, yields
a tree 100 percent resistant to weevil attack, but growth rate is
sacrificed. Back-crossing the F1 generation with Sitka spruce increases
the growth rate, but up to 50 percent of the progeny are susceptible to
weevil attack [41]. Also, although Lutz spruce is less susceptible to
the Sitka spruce weevil, it is more susceptible than Sitka spruce to the
spruce beetle [29].

Sitka spruce is susceptible to wind throw, which can account for up to
80 percent of the mortality within stands. Regeneration from gap phase
replacement, however, is rapid [15].

Control: Chemical shrub control is often required to regenerate Sitka
spruce successfully following harvest [18,36].

Readily available through nurseries within its range. Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”

General: Sitka spruce prefers cool temperatures and moisture soil. Several times in the spring, pinch the new growth of young seedlings when shoots are about one inch long to check if watering is necessary. Major pruning should be done in the early fall and all the needles should never be removed.

High strength-to-weight ratio and resonant qualities of clear lumber are  attributes that have traditionally made Sitka spruce wood valuable for  specialty uses, such as sounding boards for high-quality pianos; guitar  faces; ladders; construction components of experimental light aircraft;  oars, planking, masts, and spars for custom-made or traditional boats; and  turbine blades for wind energy conversion systems.

Ethnobotanic: The sharp needles of spruce were believed to have special powers for protection against evil thoughts (Pojar & MacKinnon 1994). The Ditidaht and other Nuu-chah-nulth peoples used the boughs in winter dance ceremonies to protect the dancers and scare spectators (Ibid.). The inner bark was eaten fresh, or dried into cakes and eaten with berries. It was also dried and grounded into a powder and used as a thickener in soups or added to cereals when making bread.

The roots were burnt over an open fire to remove the bark, then dried and split to make hats and ropes (Moerman 1998). The roots were also used by several native North American tribes to make tightly woven baskets that would hold water (Lauriault 1989). A pitch obtained from the tree was used as glue or as a protective varnish-like coat on wood (Moerman 1998).

Sitka spruce was widely employed medicinally by several native North American Indian tribes who used it especially for its antiseptic qualities in the treatment of lung complaints, sores and wounds (Moerman 1998). It has been chewed in the treatment of throat problems, coughs, and colds (Ibid.). Sitka spruce pitch was also used as a medicine for gonorrhea, syphilis, internal swelling, and toothaches (Pojar & MacKinnon 1994). A decoction of the roots has been used in the treatment of diarrhea.

Economic: Sitka spruce produces high-grade lumber that is the most important wood for airplane and glider construction. In World War II, this wood was utilized in the British Mosquito bombers (Viereck & Little 1972). Other important uses are oars, ladders, scaffolding, and boats, particularly racing sculls (Ibid.). This wood is valued in making piano sounding boards and guitars. It is harvested as saw timber and pulpwood and processed into lumber, plywood and various paper products.

Landscaping & Wildlife: Sitka spruce is often planted as an ornamental tree in the eastern and northern states and in western and northern Europe (Sargent 1961). This forest species provides habitat for a large variety of mammals, reptiles, amphibians, and birds. It is browsed only in the spring by a variety of birds.