white spruce | skymeadows

TAXONOMY: The currently accepted scientific name of white spruce
is Picea glauca (Moench) Voss. The genus Picea consists of about 30
species of evergreen trees found in cool, temperate regions of the north-
ern hemisphere. Seven species of Picea, including white spruce, are native
to North America. White spruce is widely distributed across northern
North America and exhibits considerable geographic variation. However,
some researchers think it unnecessary to distinguish varieties, although
up to four have been recognized by various other authorities.

Natural hybridization between species of Picea is common. Engelmann
spruce (Pinus engelmannii) x white spruce hybrids are common where the
ranges of these species overlap. Natural crosses between these species
occur from central British Columbia as far south as eastern Washington
and Yellowstone National Park. Within this area trees at low elevations
closely resemble pure white spruce, while pure Engelmann spruce tends
to dominate at higher elevations. Hybrids between the species are concen-
trated on intervening slopes. Sitka spruce (Pinus sitchensis) and white
spruce are sympatric in northwestern British Columbia and southwestern
Alaska. Hybrids occur in this area of sympatry, and have been classified
as Picea X lutzii Little. Hybrids between black spruce (Pinus mariana) and
white spruce are relatively rare.

NATIVE STATUS: Native, United States and Canada.

GENERAL BOTANICAL CHARACTERISTICS: White spruce is a
native, coniferous, evergreen tree. It typically grows as a medium-sized
upright tree with a long, straight trunk, and narrow, spirelike crown.
Because of poor growing conditions at the northern portion of its range,
it may grow as a short, single-trunked tree, or assume a mat or krumm-
holz form. In Alaska, white spruce is typically 40 to 70 feet (12-21 m) tall
and 6 to 18 inches (15-42 cm) in diameter. Throughout much of Canada,
white spruce's average height is about 80 feet (24 m). On good sites
throughout the range of white spruce, individual trees may grow to a
height of 100 feet (30 m) or more and attain diameters of 24 to 36 inches
(60-90 cm). The bluish-green needles are 0.75-inch-long (1.9 cm), stiff,
and four-sided. Bark on mature trees is thin, usually less than 0.3 inch
(8 mm) thick, scaly or smooth, and light-grayish brown. White spruce is
shallow-rooted. Rooting depth is commonly between 36 and 48 inches
(90-120 cm), but taproots and sinker roots may descend to 10 feet (3 m).
On northern sites, large roots are usually concentrated within 6 inches
(15 cm) of the organic-mineral soil interface. Trees often retain lower
branches, but in dense stands lower branches are gradually shed, so that
eventually the crown occupies about one-half of the tree's height. Light-
brown cones are about 2 inches (5 cm) long and hang from the branches
of the upper crown.

REGENERATION PROCESS: Plants can begin producing seed at 4
years of age but generally do not produce seed in quantity until they are
30 years of age or older. Good to excellent seed crops occur every 2 to 6
years on good sites, but in many areas, good seed crops are produced only
every 10 to 12 years. In natural stands cone production occurs primarily
on dominant and codominant trees, with sporadic production from inter-
mediate and suppressed trees. Seeds are about 0.12 inch (3 mm) long,
with a 0.25- to 0.33-inch-long (6-9 mm) wing. There are approximately
226,000 seeds per pound.

Red squirrels can reduce cone crops significantly. In interior Alaska, they
have harvested as much as 90 percent of a cone crop. Their impact on cone
and seed production is greatest during poor or medium cone crop years.
Numerous insects also reduce seed yields. The spruce cone maggot, the fir
cone worm, and the spruce seed moth are responsible for most loss. Follow-
ing dispersal, small mammals consume considerable amounts of seed off the
ground.

The winged-seeds are dispersed by wind and travel primarily in the direc-
tion of prevailing winds. Most seed falls within about 300 feet (91 m) of a
source, but seeds have been found as far as 1,300 feet (400 m) from a seed
source. Seeds found considerable distances from a source probably travel
over crusted snow. A study in Alaska found that 50 percent of seed fell
within 90 feet (27 m), and 90 percent of seed fell within 210 feet (64 m) of
a 60-foot-tall tree. Red squirrels disperse seeds also. White spruce repro-
duction is common at squirrel middens.

White spruce seeds remain viable for only about 1 to 2 years. Under natur-
al conditions, seeds overwinter under snow and germinate in the spring or
summer when there is adequate moisture and soil temperatures have
warmed.

SITE CHARACTERISTICS: White spruce occupies boreal forests. It is
largely confined to well-drained uplands or river terraces and floodplains.
In interior Alaska and the Northwest Territories, white spruce forests are
usually found on stream bottoms, river terraces and lake margins, and on
warm, well-drained, south-facing slopes within 5 miles (8 km) of major
river valleys. Seral stands of white spruce and aspen, and white spruce
and birch, are common on relatively dry slopes with a south or southwest
exposure, and on dry, excessively drained outwash or deltaic soils. Across
northern Alaska, white spruce grows at the northern limit of tree growth
where it forms open communities on dry exposed sites. At arctic timber-
line, white spruce grows in well-drained soils, often along streams where
permafrost has been melted away by flowing water. In British Columbia
and Alberta, white spruce is widely distributed, occupying floodplains, foot-
hills, and mountains from 2,500 to 5,000 feet (762-1,524 m) in elevation.
In northeastern Alberta, open, parklike white spruce forests occur on high
ridges, stony beaches, and dune habitats. In eastern Canada, the Lake
States, and the northeastern United States, white spruce occurs in many
coniferous and mixed coniferous-hardwood forests. Pure stands or mixed
stands where it is dominant are not widespread. Conifers, including white
spruce, tend to occupy shallow outwash soils on upper slopes and flats,
while hardwoods or mixtures of hardwoods and spruce are found on deep
glacial till soils of lower slopes.

Seedling establishment is best on mineral soil. White spruce may also
establish on shallow organic seedbeds, but rarely establish where organic
layers are thicker than 2 to 3 inches (5-8 cm). Seedlings are frequently
found on rotten wood. White spruce grows on a wide variety of soils of
glacial, lacustrine, marine, or alluvial origin. It grows well on loams, silt
loams, and clays, but rather poorly on sandy soils. It is somewhat site
demanding, and often restricted to sites with well-drained, basic mineral
soils. White spruce grows poorly on sites with high water tables and is
intolerant of permafrost. In the Lake States and northeastern United
States, it grows mostly on acid Spodosols, Inceptisols, or Alfisols, with a
pH ranging from 4.0 to 5.5. In the Northeast, it grows well on calcareous
and well-drained soils but is also found extensively on acidic rocky and
sandy sites, and in some fen peatlands in coastal areas.

Seedlings grow best in full sunlight, but are tolerant of low light, and can
withstand many years of suppression.

SUCCESSIONAL STATUS: White spruce is a long-lived climax tree that
gradually replaces pine, aspen, birch, and/or poplar on well-drained sites.
Less frequently it occurs as an early successional species, forming pure
stands or mixing with seral hardwoods immediately after fire. Its ability
to successfully establish following fire depends on fire severity and inten-
sity, and seed production during the year of the fire. Following stand des-
troying fires, dense stands of aspen, birch, and/or poplar tend to develop
quickly, and these successional species are often scattered throughout all
but the oldest white spruce stands. White spruce seedlings establish under
these seral hardwoods, develop and grow slowly, and eventually replace
them. White spruce-aspen, white spruce-birch, and white spruce-balsam
poplar are common mid-successional communities that, with the continued
absence of fire, will gradually be replaced by essentially pure stands of
white spruce.

SEASONAL DEVELOPMENT: Pollen shedding may occur in May, June,
or July, with southern areas having earlier dispersal than northern areas.
Pollen shedding is temperature dependent and may vary yearly by as
much as 4 weeks at any given location. Cones ripen in August or Septem-
ber, about 2 to 3 months after pollen shed. Timing of seedfall varies yearly
depending on climatic conditions. Cool, wet weather delays seedfall, but
under warm and dry conditions cones open and seeds disperse early. In
general seedfall begins in late August or September. Following dispersal,
cones remain on the tree for 1 to 2 years.

GENERAL DISTRIBUTION: White spruce has a transcontinental
distribution. It grows from Newfoundland, Labrador, and northern
Quebec west across Canada along the northern limit of trees to north-
western Alaska, south to southwestern Alaska, southern British Columbia,
southern Alberta, and northwestern Montana, and east to southern Mani-
toba, central Minnesota, central Michigan, southern Ontario, northern
New York, and Maine. An isolated population also occurs in the Black
Hills of South Dakota and Wyoming.

SKY MEADOWS DISTRIBUTION:

Tree specimens can be found on trails marked in red.

       Bleak House
       Appalachian Trail/Old Trail
       South Ridge/North Ridge
       Gap Run
       Snowden
       Woodpecker Lane

       Sherman's Mill
       Rolling Meadows/ Lost Mountain
     Fish Pond

HABITAT TYPES AND PLANT COMMUNITIES: Climax white
spruce forests are widespread across Alaska and northwestern Canada.
They consist almost entirely of white spruce, but may have scattered
black spruce, paper birch (Betula papyrifera), aspen (Populus tremuloides),
and balsam poplar (Populus balsamifera) present. Climax stands are often
broken up by extensive seral communities resulting from forest fires.

In eastern Canada and the northeastern United States, white spruce
occurs as a climax species in pure or mixed stands. Within the fog belt of
Quebec and Labrador, white spruce forms pure stands near the seaboard.
At climax, it often codominates or forms a significant part of the vegetation
in mixed stands with red spruce (Picea rubens), balsam fir (Abies
balsamea), and black spruce.

IMPORTANCE AND USES: Livestock and wild ungulates rarely eat
white spruce. Snowshoe hares sometimes feed heavily on white spruce
saplings and seedlings. On a cut-over site in northern Alberta, 40 percent
of 2- and 3-year-old white spruce seedlings were browsed by hares. In
Alaska, white spruce needles, bark, and twigs comprise a major portion of
the snowshoe hare's winter diet. During this time of the year, snow covers
many other foods, leaving only trees and shrubs above snowline available
for hares to browse. Mice and voles eat spruce seedlings. Red squirrels
clip twigs and feed on vegetative and reproductive buds in the spring.
Consumption of leaders and the ends of upper branches by red squirrels
tends to be greatest during poor cone crop years. Spruce grouse feed
entirely on spruce needles during winter.

Numerous seed-eating birds and mammals feed on white spruce seed.
White spruce seed is a primary food of red squirrels. White spruce habitats
are favored by red squirrels because of the highly palatable seeds; squirrel
density is much greater in white spruce stands than black spruce stands.
Red squirrels are so dependent on this food source that population density
is directly related to the periodicity of good seed crops. Mice, voles, shrews,
and chipmunks consume large quantities of white spruce seeds off the
ground. Chickadees, nuthatches, crossbills, and the pine siskin extract
seeds from open spruce cones and eat seeds off the ground.

White spruce is not a preferred browse. Its palatability is low for moose,
elk, white-tailed deer, and mule deer, but it may be moderately palatable
to bighorn sheep. Red squirrels prefer white spruce seed over black
spruce seed.

White spruce provides good wildlife cover. It may be particularly impor-
tant as winter shelter, especially to caribou which use it for protection
from strong winter winds.

White spruce is useful for long-term revegetation of coal mine overburden.
In Alberta, it is considered one of the best conifers for this purpose. White
spruce x Engelmann spruce hybrids have been observed naturally invad-
ing coal mine spoils at high elevations in west-central Alberta. White spruce
has also naturally invaded coal mine overburden in south-central Alaska.
At this location, the overburden had a clay content of 42 to 44 percent, and
was redeposited on the mined area and graded back to the original contour.
On anthracite strip mine spoils, however, survival of planted white spruce
seedlings was poor to adequate after 5 years.

Results of direct seeding of white spruce onto logged-over areas and aban-
doned farmland has been variable. The fact that it naturally invades mine
spoils indicates, however, that direct seeding may be useful on some dis-
turbed sites.

White spruce wood is light, straight-grained, and resilient. It is an impor-
tant commercial tree harvested primarily for pulpwood and lumber for
general construction. Logs are used extensively for cabin construction.
It has also been used for specialty items such as sounding boards, paddles
and oars, cabinets, boxes, and food containers.

White spruce can be planted as an ornamental and used in shelterbelt
plantings.

White spruce was important to native peoples of interior Alaska. Poles
were used to construct dwellings, and bark was used as roofing material.
Thin, straight, pliable roots were used as rope. Pitch, watery sap, and
extracts from boiled needles were used for various medicinal purposes.
Boughs were used for bedding, and rotten wood for smoking moose hides.

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