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
Regularity: Regularly occurring
Regularity: Regularly occurring
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,
Sitka spruce has been extensively introduced into the British Isles
Regional Distribution in the Western United States
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
Occurrence in North America
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).
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 .
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 . The base of the bole is buttressed . When forest grown
the bole is long and free of lower limbs .
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
Puget Lowland Forests Habitat
Cope's giant salamander is found in the Puget lowland forests along with several other western North America ecoregions. The Puget lowland forests occupy a north-south topographic depression between the Olympic Peninsula and western slopes of the Cascade Mountains, extending from north of the Canadian border to the lower Columbia River along the Oregon border. The portion of this forest ecoregion within British Columbia includes the Fraser Valley lowlands, the coastal lowlands locally known as the Sunshine Coast and several of the Gulf Islands. This ecoregion is within the Nearctic Realm and classified as part of the Temperate Coniferous Forests biome.
The Puget lowland forests have a Mediterranean-like climate, with warm, dry summers, and mild wet winters. The mean annual temperature is 9°C, the mean summer temperature is 15°C, and the mean winter temperature is 3.5°C. Annual precipitation averages 800 to 900 millimeters (mm) but may be as great as 1530 mm. Only a small percentage of this precipitation falls as snow. However, annual rainfall on the San Juan Islands can be as low as 460 mm, due to rain-shadow effects caused by the Olympic Mountains. This local rain shadow effect results in some of the driest sites encountered in the region. Varied topography on these hilly islands results in a diverse assemblage of plant communities arranged along orographically defiined moisture gradients. Open grasslands with widely scattered trees dominate the exposed southern aspects of the islands, while moister dense forests occur on northern sheltered slopes characterized by Western red cedar (Thuja plicata), Grand fir (Abies grandis), and Sword fern (Polystichum munitum) communities.
There are only a small number of amphibian taxa in the Puget lowland forests, namely: Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); Long-toed salamander (Ambystoma macrodactylum); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Pacific chorus frog (Pseudacris regilla); Coastal giant salamander (Dicamptodon tenebrosus); Rough-skin newt (Taricha granulosa); the Vulnerable Spotted frog (Rana pretiosa); Tailed frog (Ascopus truei); and Northern red-legged frog (Rana aurora).
Likewise there are a small number of reptilian taxa within the ecoregion: Common garter snake (Thamnophis sirtalis); Western terrestrial garter snake (Thamnophis sirtalis); Northern alligator lizard (Elgaria coerulea); Western fence lizard (Sceloporus occidentalis); Northwestern garter snake (Thamnophis ordinoides); Sharp-tailed snake (Contia tenuis); Yellow-bellied racer (Coluber constrictor); and Western pond turtle (Clemmys marmorata).
There are numberous mammalian taxa present in the Puget lowland forests. A small sample of these are:Creeping vole (Microtus oregoni), Raccoon (Procyon lotor), Southern sea otter (Enhydra lutris), Mink (Mustela vison), Coyote (Canis latrans), Black-tailed deer (Odocoileus hemionus), Pallid bat (Antrozous pallidus), and Harbour seal (Phoca vitulina).
A rich assortment of bird species present in this ecoregion, including the Near Threatened Spotted owl (Strix occidentalis), Turkey vulture (Cathartes aura), Bald eagle (Haliaeetus leucocephalus), Blue grouse (Dendragapus obscurus), as well as a gamut of seabirds, numerous shorebirds and waterfowl.
Habitat and Ecology
Central Pacific Coastal Forests Habitat
This taxon is found in the Central Pacific Coastal Forests ecoregion, as one of its North American ecoregions of occurrence. These mixed conifer rainforests stretch from stretch from southern Oregon in the USA to the northern tip of Vancouver Island, Canada. These forests are among the most productive in the world, characterized by large trees, substantial woody debris, luxuriant growths of mosses and lichens, and abundant ferns and herbs on the forest floor. The major forest complex consists of Douglas-fir (Pseudotsuga menziesii) and Western hemlock (Tsuga heterophylla), encompassing seral forests dominated by Douglas-fir and massive old-growth forests of Douglas-fir, Western hemlock, Western red cedar (Thuja plicata), and other species. These forests occur from sea level up to elevations of 700-1000 meters in the Coast Range and Olympic Mountains. Such forests occupy a gamut of environments with variable composition and structure and includes such other species as Grand fir (Abies grandis), Sitka spruce (Picea sitchensis), and Western white pine (Pinus monticola).
Characteristic mammalian fauna include Elk (Cervus elaphus), Black-tailed Deer (Odocoileus hemionus), Coyote (Canis latrans), Black Bear (Ursus americanus), Mink (Mustela vison), and Raccoon (Procyon lotor).
The following anuran species occur in the Central Pacific coastal forests: Coastal tailed frog (Ascaphus truei); Oregon spotted frog (Rana pretiosa VU); Northern red-legged frog (Rana pretiosa); Pacific chorus frog (Pseudacris regilla); Cascade frog (Rana cascadae NT), generally restricted to the Cascade Range from northern Washington to the California border; Foothill yellow-legged frog (Rana boylii) and the Western toad (Anaxyrus boreas NT). A newt found in the ecoregion is the Rough skinned newt (Taricha granulosa).
Salamanders within the ecoregion are: Del Norte salamander (Plethodon elongatus NT); Van Dyke's salamander (Plethodon vandykei); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Olympic torrent salamander (Rhyacotriton olympicus VU), whose preferred habitat is along richly leafed stream edges; Long-toed salamander (Ambystoma macrodactylum), whose adults are always subterranean except during the breeding season; Dunn's salamander (Plethodon dunni), usually found in seeps and stream splash zones; Clouded salamander (Aneides ferreus NT), an aggressive insectivore; Monterey ensatina (Ensatina eschscholtzii), usually found in thermally insulated micro-habitats such as under logs and rocks; Pacific giant salamander (Dicamptodon tenebrosus), found in damp, dense forests near streams; and Cope's giant salamander (Dicamptodon copei), usually found in rapidly flowing waters on the Olympic Peninsula and Cascade Range.
There are a small number of reptilian taxa that are observed within this forested ecoregion, including: Pacific pond turtle (Emys marmorata); Common garter snake (Thamnophis sirtalis), an adaptable snake most often found near water; Northern alligator lizard (Elgaria coerulea); and the Western fence lizard.
Numerous avian species are found in the ecoregion, both resident and migratory. Example taxa occurring here are the Belted kingfisher (Megaceryle alcyon); Wild turkey (Meleagris gallopavo); and the White-headed woodpecker (Picoides albolarvatus) and the Trumpeter swan (Cygnus buccinator), the largest of the North American waterfowl.
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 . Sitka spruce grows best on sites
with deep, moist, well-drained soils . It can tolerate the salty
ocean spray of seaside dunes, headlands, and beaches, and the brackish
water of bogs . 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 .
Elevation: Sitka spruce grows from sea level to timberline in Alaska (0
to 3,900 feet (0-1,189 m))  with elevational limitations of 2,000
feet (600 m) in Washington and 1,500 feet (450 m) in Oregon and
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)
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) .
Key Plant Community Associations
Sitka spruce is listed as a dominant overstory species in the following
Natural vegetation of Oregon and Washington .
Plant association and management guide: Sinslaw National Forest .
Preliminary classification of forest vegetation of the Kenai
Peninsula, Alaska .
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):
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce
Habitat: Cover Types
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
Habitat: Plant Associations
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
Soils and Topography
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).
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
Habitat & Distribution
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.).
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
Associated Forest Cover
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
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).
Diseases and Parasites
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.
Fire Management Considerations
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  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 .
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 .
However, removal of the slash by burning in Sitka spruce forests is not
required because of the to rapid decay in that moist environment .
Burning is not recommended on steep slopes and where water quality may
be degraded [48,53].
Plant Response to Fire
Sitka spruce will invade a burned site via wind-dispersed seed from
adjacent unburned forests . Wind-dispersed seed travels 33 to 880
yards (30-792 m) from the parent tree .
Immediate Effect of Fire
The immediate effect of a cool to hot fire is damage to the cambium
layer, usually resulting in death of the tree [5,8].
Fire is not an important factor in the ecolgy of Sitka spruce . 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 .
More info for the term: climax
Sitka spruce is a shade-intolerant species  that is both a pioneer
and a climax species . 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 .
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 . The seeds are small with a mean of 210,000
cleaned seeds per pound (467,000/kg) . 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
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 . 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 . 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 .
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  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 .
Growth Form (according to Raunkiær Life-form classification)
Reaction to Competition
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.
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).
Life History and Behavior
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 .
Seed Production and Dissemination
Flowering and Fruiting
Growth and Yield
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).
Evolution and Systematics
Western hemlock-Sitka spruce forests maintain diversity partly thanks to wind disturbance patterns.
"The dynamics of British planted forests are compared with disturbance dynamics of analogous natural forests with particular reference to disturbance by strong winds. Western hemlock-Sitka spruce (Tsuga heterophylla-Picea sitchensis) forests in the Pacific North-west of North America and particularly South-east Alaska provide the most promising comparison. There are few reports on disturbance in these forests, but the regime includes both gap-phase and stand replacement dynamics due to wind. However, the landscape proportion and pattern of resulting structural types are not well defined…Two stand types have been identified in the hemlock-spruce forest types in the Pacific North-west: (1) even-aged stands following catastrophic blowdown; and (2) multi-aged stands resulting from gradual but non-catastrophic attrition (Deal et al., 1991). Sitka spruce can maintain a presence in forest communities in both situations (Taylor, 1990). It is not known what the proportion of the two stand types (fine grain and even-aged) is for any one region." (Quine et al. 1999:337, 347)
Learn more about this functional adaptation.
- Quine CP; Humphrey JW; Ferris R. 1999. Should the wind disturbance patterns observed in natural forests be mimicked in planted forests in the British uplands?. Forestry. 72(4): 337-358.
Molecular Biology and Genetics
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).
Barcode data: Picea sitchensis
Statistics of barcoding coverage: Picea sitchensis
Public Records: 6
Specimens with Barcodes: 9
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
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.
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  and Schoen and Kirchhoff
. 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  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 .
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 .
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 . Also, although Lutz spruce is less susceptible to
the Sitka spruce weevil, it is more susceptible than Sitka spruce to the
spruce beetle .
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 .
Control: Chemical shrub control is often required to regenerate Sitka
spruce successfully following harvest [18,36].
Cultivars, improved and selected materials (and area of origin)
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.
Relevance to Humans and Ecosystems
Sitka spruce forests provide hiding and thermal cover for a large
variety of mammals. Old-growth Stika spruce forests in Alaska and
British Columbia are critical winter habitat for the Sitka deer. Old
growth provides thermal cover and acts as a snow screen, allowing easier
access to browse species [25,51]. Sitka deer require large blocks of
old growth from sea level to the alpine and subalpine environments for
migrational movements from summer to winter range . Sitka spruce
forests also provide habitat for Roosevelt elk, woodland caribou ,
Alaskan brown bear, and mountain goat .
Sitka spruce provides good nesting and roosting habitat for avifauna
[52,56]. Snags and live trees with broken tops provide nesting habitat
for primary and secondary cavity nesters . The bald eagle uses
primarily (greater than 90 percent) Sitka spruce for nesting trees on
Admiralty Island , and also uses them as roosting trees to survey
the incoming breakers for food . The peregrine falcon in coastal
British Columbia uses Stika spruce for platform nesting and secondary
cavity nesting .
Importance to Livestock and Wildlife
Sitka spruce forests in various phases of succession provide habitat, in
many cases critical habitat, for a large variety of mammals, game and
nongame birds, reptiles, and amphibians [7,19,43]. Its value as a
browse species for large ungulates is poor , while it has fair to
good value for some game birds .
Wood Products Value
wood, with its high strength to weight ratio, is valuable for use as
turbine blades for wind-driven electrical generators, masts for sail
boats, ladders, oars , boats, and racing sculls . Sitka
spruce's high resonant quality makes it valuable in the manufacture of
piano sounding boards and guitars. The wood from Sitka spruce is also
used in saw timber, high-grade wood pulp, and plywood [30,55].
Other uses and values
can be woven to produce baskets and rain hats. The pitch was used for
calking canoes , for chewing, and medicinal purposes .
Pioneers split Stika spruce into shakes for roofing and siding .
Sitka spruce also has limited food value for humans, for the inner bark
and young shoots may be eaten as emergency food. Tea can be made from
the young shoots .
In the first half of this century Sitka spruce provided most of the wood
for stuctural components of World War I and II aircraft [5,55]. More
recently it has been used as the nose cones for missiles and space craft
Value for rehabilitation of disturbed sites
the glaciers retreat. On the Juneau Icefield, Sitka spruce has
colonized "nunatacks" (rocky peaks) protruding through the icefield .
Sitka spruce also acted as an aggressive pioneer on uplifted terrain
from the 1964 earthquake .
only in the spring, and then only the new growth [5,11]. In Alaska and
British Columbia the needles comprise up to 90 percent of the winter
diet of blue grouse .
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.
Picea sitchensis, the Sitka spruce, is a large coniferous evergreen tree growing to almost 100 m tall, and with a trunk diameter at breast height that can exceed 5 m (see List of superlative trees. 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 reach 300 feet in height. It acquires its name from the community of Sitka, Alaska.
The bark is thin and scaly, flaking off in small circular plates 5–20 cm 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. 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 long  and 2 cm broad when closed, opening to 3 cm broad. They have thin, flexible scales 15–20 mm 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 long, with a slender, 7–9 mm 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 tall may still be seen in the 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 the Olympic National Park, Washington and Prairie Creek Redwoods State Park, California (USA); two at the last site are just over 96 m (315 ft) tall. The Queets Spruce is the largest in the world with a trunk volume of 337 m3 (11,900 cu ft) it is 75.6 m (248 ft) tall and 455 cm (15 ft) in dbh. It is located near the Queets River in Olympic National Park, about 26 kilometres (16 mi) from the Pacific Ocean.
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 (Van Pelt, 2001).
DNA analysis has shown that only Picea breweriana has a more basal position than Sitka spruce to the rest of the spruce. The other thirty-three species of spruce are more derived which suggests that Picea originated in North America.
Distribution and habitat
Sitka spruce is native to the west coast of North America, with its northwestern limit on Kodiak Island, Alaska, and its southeastern limit near Fort Bragg in northern California (Griffin & Critchfield 1972). It is closely associated with the temperate rain forests 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 nowhere does its range extend more than 80 km from the Pacific Ocean and its inlets.
Sitka spruce is of major importance in forestry for timber and paper production. Outside its native range, it is particularly valued for its fast growth on poor soils and exposed sites where few other trees can be grown successfully; in ideal conditions young trees may grow 1.5 m per year. It is naturalized in some parts of Ireland and Great Britain where it was introduced in 1831 (Mitchell, 1978) 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 50,000 hectares 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.
Sitka spruce is used widely in piano, harp, violin, and guitar manufacture, as its high strength-to-weight ratio and regular, knot-free rings make it an excellent conductor of sound. For these reasons, the wood is also an important material for sailing boat spars, aircraft wing spars (including flying models), and the nosecones of Trident missiles. The Wright brothers' Flyer was built using Sitka spruce, as were many aircraft before World War II; during that war, aircraft such as the British Mosquito used it as a substitute for strategically important aluminium.
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 Native American 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 Olympic National Forest in Washington, Sitka spruce trees near the ocean sometimes develop tumors, also called 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."
- Rushforth, Keith (1986) . Bäume [Pocket Guide to Trees] (in German) (2nd ed.). Bern: Hallwag AG. ISBN 3-444-70130-6.
- "Agathis australis". Conifers. Retrieved April 9, 2012.
- "Tallest Sitka Spruce". Landmark Trees. Retrieved April 9, 2012.
- "Picea sitchensis". Oregon State University. Retrieved April 9, 2012.
- Ran, J.-H., Wei, X.-X. & Wang, X.-Q. 2006. Molecular phylogeny and biogeography of Picea (Pinaceae): Implications for phylogeographical studies using cytoplasmic haplotypes. Mol Phylogenet Evol. 41(2): 405–19.
- Sigurgeirsson, A. & Szmidt, A.E. 1993. Phylogenetic and biogeographic implications of chloroplast DNA variation in Picea. Nordic Journal of Botany 13(3): 233–246.
- Dammert, L (2001). Dressing the landscape: afforestation efforts on Iceland, Unasylva Vol. 52, No. 207.
- Hermann, R (1987). North American Tree Species in Europe (PDF), Journal of Forestry.
- Sitkagran - utbredelse, egenskaper og anvendelse (Sitka spruce - propagation, properties and uses) by Kjell Vadla, Norwegian Forest and Landscape Institute.
- Yates, D.; Torczyner, R.; Sidwell, D. (1975). "Development and application of woven graphite products for aerospacestructures". doi:10.2514/6.1975-774.
- "Picea sitchensis: "Sitka Spruce, Tideland Spruce"". Collections. San Francisco Botanical Garden. Retrieved November 29, 2013.
- "Alaska State Tree: Sitka Spruce". Alaskan Nature. Retrieved November 29, 2013.
- Kallenbach, Elizabeth. "Tlingit Spruce Root Baskets". University of Oregon, Museum of Natural and Cultural History. Retrieved November 29, 2013.
- Stilbene glucosides in the bark of Picea sitchensis. Masakazu Aritomi, Dervilla M.X. Donnelly, Phytochemistry, Volume 15, Issue 12, 1976, Pages 2006–2008, doi:10.1016/S0031-9422(00)88881-0
- Astringin and isorhapontin distribution in Sitka spruce trees. Claudia D. Toscano Underwood and Raymond B. Pearce, Phytochemistry, Volume 30, Issue 7, 1991, Pages 2183–2189, doi:10.1016/0031-9422(91)83610-W
- Sedam, Michael T. (2002). The Olympic Peninsula: The Grace & Grandeur. Voyageur Press. p. 109. ISBN 978-0896584587.
Sitka spruce ( Picea sitchensis ) is the state tree of Alaska.
Names and Taxonomy
The currently accepted scientific name of Sitka spruce is Picea
sitchensis (Bongard) Carriere (Pinaceae) [28,50].
Species within the genus Picea form hybrid swarms at the interface of
their ranges. Sitka spruce naturally hybridizes with white spruce (P.
glauca) to produce Lutz spruce (Picea X lutzii Little) [22,23,24,55].
It is often difficult to identify Picea X lutzii by morphological
chacteristics in stands with low levels of introgression .
Sitka spruce in plantations will also hybridize with Yezo spruce (Picea
jezoensis), Serbian spruce (P. omorika), and Engelmann spruce (P.