Sitka Spruce

Sitka spruce
tideland spruce
coast spruce
yellow spruce
silver spruce
western spruce
Menzies' spruce

More info for the terms: cover, woodland

Sitka spruce forests provide hiding and thermal cover for a large
variety of mammals. Old-growth Sitka 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 [51]. Sitka spruce
forests also provide habitat for Roosevelt elk, woodland caribou [19],
Alaskan brown bear, and mountain goat [42].

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 [27]. The bald eagle uses
primarily (greater than 90 percent) Sitka spruce for nesting trees on
Admiralty Island [42], and also uses them as roosting trees to survey
the incoming breakers for food [5]. The peregrine falcon in coastal
British Columbia uses Sitka spruce for platform nesting and secondary
cavity nesting [9].

More info for the terms: forest, 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].

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].

More info for the term: fire regime

Fire is not an important factor in the ecology 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].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".

More info for the terms: competition, fire exclusion, forest, seed

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].

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More info for the term: phanerophyte

Phanerophyte

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]. Sitka 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, Sitka 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 horridus), salmonberry
(Rubus spectablis), and thimbleberry (R. parviflorus) [24].

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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 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

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

More info for the term: forest

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

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: succession

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 [11], while it has fair to
good value for some game birds [42].

More info for the terms: association, forest, 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: Siuslaw National Forest [27].
Preliminary classification of forest vegetation of the Kenai
Peninsula, Alaska [46].

More info for the term: tree

Tree

More info for the terms: phase, 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].

AK CA HI OR WA BC YT

Native Americans have used Sitka spruce for various purposes. The roots
can be woven to produce baskets and rain hats. The pitch was used for
calking canoes [5], for chewing, and medicinal purposes [47].

Pioneers split Sitka spruce into shakes for roofing and siding [5].

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 [47].

In the first half of this century Sitka spruce provided most of the wood
for structural 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
[50].

Sitka spruce is slightly palatable to large ungulates. It is browsed
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 [42].

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More info for the terms: fruit, seed

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].

More info for the terms: seed, 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].

Secondary colonizer - offsite seed

More info for the terms: epigeal, forest, layering, seed

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
substrate, 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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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

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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 spruce 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 term: introgression

The 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 [23].

Sitka spruce in plantations will also hybridize with Yezo spruce (Picea
jezoensis), Serbian spruce (P. omorika), and Engelmann spruce (P.
engelmannii) [22,23,24].

Sitka spruce is a pioneer species which colonizes glacial moraines as
the glaciers retreat. On the Juneau Icefield, Sitka spruce has
colonized "nunatacks" (rocky peaks) protruding through the icefield [6].
Sitka spruce also acted as an aggressive pioneer on uplifted terrain
from the 1964 earthquake [4].

Sitka spruce is the most important timber species in Alaska [5]. The
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 [24], boats, and racing sculls [55]. 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].