Barton M. Blum
Red spruce (Picea rubens), also known as yellow spruce, West Virginia spruce, eastern spruce, and he-balsam, is one of the more important conifers in the northeastern United States and adjacent Canada. It is a medium-size tree that may grow to be more than 400 years old. The wood of red spruce is light in color and weight, straight grained, and resilient. It is used for making paper, for construction lumber, and for musical stringed instruments. Its many uses rival those of eastern white pine (Pinus strobus) (21).
Red spruce reaches heights of 60 to 80 feet with trunk diameters of nearly two feet. Larger sizes are attained in the southern Appalachians. Needles are four sided, dark, shiny, yellow-green, and about 1/2 inch long, growing singly from all sides of the twigs and branches. The slender new twigs have a reddish coat of down through the first year. This, together with the short incurved needles, help distinguish red spruce from most other spruces. There are about 139,000 seeds per pound.
Regularity: Regularly occurring
Regularity: Regularly occurring
Brunswick, west to Maine, southern Quebec, and southeastern Ontario, and
south to central New York, northeastern Pennsylvania, northern New
Jersey, and northeastern Massachusetts. Its range extends south in the
Appalachian Mountains of extreme western Maryland, eastern West
Virginia, northern and western Virginia, western North Carolina, and
eastern Tennessee .
Occurrence in North America
VT VA WV NB NS PE PQ
- The native range of red spruce.
Distribution and adaptation
In northern New England it is found mainly on shallow till soils that average about 18 inches deep to a compact layer. At higher elevations it often grows in organic soils overlying rocks. On poorly drained soils, lack of aeration limits its growth. In the northern part of its range, red spruce grows at elevations from near sea level to about 4,500 feet. In the southern Appalachians it is limited to slopes and mountain tops above 3,500 feet in West Virginia and above 4,500 feet in Tennessee and North Carolina.
Unfortunately, red spruce is showing damage from air pollution throughout its range, particularly at the higher elevations.
For a current distribution map, please consult the Plant Profile page for this species on the PLANTS Website.
Red spruce is a native, evergreen conifer. It is a medium-sized tree,
attaining a maximum height of 115 feet (35 m); the average mature height
is 60 to 75 feet (18-23 m). The ovulate cones are 1.3 to 1.5 inches
(3-4 cm) long, with rigid rounded scales that are often slightly toothed
on the edges. Red spruce is very shallow rooted; most of the feeding
roots occur in the duff and top few centimeters of soil. In Maine, the
average depth of roots was 13 inches (33 cm), with a maximum depth of 22
inches (56 cm) . Red spruce is long-lived, often achieving ages
greater than 350 years .
Habitat and Ecology
Red spruce grows in climates with cool, moist summers and cold winters
. In the northeastern United States, the mean annual precipitation
ranges from 36 to 52 inches (910-1,320 mm) and is often higher in the
mountainous terrain where red spruce occurs, due to fog drip. Snow
cover averages 80 to 160 inches (203-406 cm), with 100 to 140 days of
snow cover per year .
Most of the soils on which red spruce occurs are developed from glacial
deposits. The most productive soils are derived from parent materials
of unsorted glacial drift and till deposited on the midslopes of hills
and mountains. Soils on red spruce sites are usually acid Spodosols,
Inceptisols, and sometimes Histosols with thick mor humus and a
well-defined A2 horizon. Soil pH ranges from 4.0 to 5.5. Red spruce is
often found on sites that are unfavorable for other species, such as
organic soils overlying rocks in mountainous locales, on steep rocky
slopes with thin soils, and in wet bottomlands .
In the northern part of its range, red spruce occurs at elevations
ranging from sea level to 4,500 feet (0-1,370 m), above which it is
usually replaced by balsam fir (Abies balsamea). The elevational
zonation of species is defined as follows :
up to 1,485 feet (450 m) northern hardwoods (hemlock phase)
1,486 to 2,508 feet (451- 760 m) northern hardwoods (spruce phase)
2,508 to 4,026 feet (761-1,220 m) subalpine (spruce-fir phase)
4,027 to 4,785 feet (1,221-1,450 m) subalpine (fir phase)
In the southern Appalachian Mountains, red spruce occurs at elevations
from about 3,200 feet to 6,200 feet (980-1,890 m); above 6,200 feet
(1,890 m), red spruce tends is usually replaced by Fraser fir (Abies
Key Plant Community Associations
Red spruce is a common dominant or codominant in the red spruce and the
spruce-fir forests of the northeastern United States and adjacent
Shrub associates of red spruce in the Adirondack Mountains of New York
include red raspberry (Rubus idaeus), dwarfed blackberry (R. pubescens),
hobblebush (Viburnum alnifolium), Canada yew (Taxus canadensis), and
American fly honeysuckle (Lonicera canadensis). Ground layer herbs
include wild sarsaparilla (Aralia nudicaulis), Aster acuminatus, yellow
beadlily (Clintonia borealis), and common wood-sorrel (Oxalis montana).
Common bryophytes found in old-growth red spruce forests in the
Adirondacks include Brotherella recurvans, Schreber's moss (Pleurozium
schreberi), Polytrichum ohioense, mountain fern moss (Hylocomium
splendens), Bazzania trilobata, ptilium (Ptilium crista-castrensis),
Drepanocladus uncinatus, Dicranum scoparium, and D. montanum .
In the southern Appalachian Mountains, arboreal associates include
Fraser fir (Abies fraseri), yellow buckeye (Aesculus octandra), sweet
birch (Betula lenta), and black cherry (Prunus serotina) in addition to
those found in the northern part of its range [59,79,87]. Understory
associates in openings include rhododendrons (Rhododendron spp.),
American mountain-ash (Sorbus americana), and wild raisin (Viburnum
cassinoides). Other understory associates include highbush cranberry
(Viburnum edule), mountain holly (Ilex montana), mountain laurel (Kalmia
latifolia), speckled alder (Alnus rugosa), pin cherry (Prunus
pensylvanica), serviceberry (Amelanchier spp.), raspberries (Rubus
spp.), and blueberries and huckleberries (Vaccinium spp.). In closed
red spruce stands, mosses, lichens, and clubmosses predominate in the
understory along with wood sorrel (Oxalis spp.), trillium (Trillium
spp.), and checkerberry wintergreen (Gaultheria procumbens) .
Publications describing habitat or cover types in which red spruce is
dominant or codominant include:
(1) Proceedings of the Region 9 Land Systems conference on the White
Mountain National Forest 
(2) The Hubbard Brook ecosystem study: composition and dynamics of the
tree stratum 
(3) Ground vegetation patterns of the spruce-fir area of the Great
Smoky Mountains National Park 
(4) Spruce-fir forests of the coast of Maine 
(5) Forest type studies in the Adirondack region 
(6) The classification and evaluation of site for forestry 
(7) The identification and description of forest sites 
(8) Old-growth forests of Adirondack Park, New York 
(9) Vegetation-environment relationships in virgin, middle elevation
forests in the Adirondack Mountains, New York 
(10) Natural ecological communities of New York State 
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K108 Northern hardwoods - spruce forest
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):
FRES10 White - red - jack pine
FRES11 Spruce - fir
FRES18 Maple - beech - birch
FRES19 Aspen - birch
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
5 Balsam fir
12 Black spruce
17 Pin cherry
18 Paper birch
21 Eastern white pine
22 White pine - hemlock
23 Eastern hemlock
24 Hemlock - yellow birch
25 Sugar maple - beech - yellow birch
27 Sugar maple
30 Red spruce - yellow birch
31 Red spruce - sugar maple - beech
32 Red spruce
33 Red spruce - balsam fir
34 Red spruce - Fraser fir
35 Paper birch - red spruce - balsam fir
37 Northern white-cedar
60 Beech - sugar maple
107 White spruce
108 Red maple
Soils and Topography
In the northern part of its range, red spruce grows at elevations from near sea level to about 1370 m (4,500 ft) (22). In the southern Appalachian Mountains it comes in at elevations as low as 1370 m (4,500 ft) and from there to about 1520 m (5,000 ft) it is mixed with hardwoods and eastern hemlock (Tsuga canadensis). At 1520 m (5,000 ft) balsam fir (Abies balsamea) joins with red spruce to form the dominant spruce-fir climax type. In West Virginia, spruce-fir stands are found as low as 980 m (3,200 ft). Above 1890 m (6,200 ft) in the southern Appalachians, red spruce appears less frequently than Fraser fir (Abies fraseri) (47). In the White Mountains of New Hampshire, balsam fir is the predominant species above 1220 m (4,000 ft) but red spruce is well represented from about 790 to 1010 m (2,600 to 3,300 ft) (27).
Habitat & Distribution
Good seed production of red spruce usually begins after the tree is 30 years old. Heavy seed crops occur every three to eight years. Spruce seedlings have exceptionally slow growing, fibrous, shallow roots. Consequently, a critical survival factor in natural establishment is the depth of the organic layers on which the seed germinates. If the thickness of the layer exceeds two inches, the roots of spruce seedlings may not reach mineral soil and the moisture needed to carry them through dry periods. Red spruce is very shade tolerant, but requires nearly full sun light for optimum development.
Red spruce can be established in nurseries as easily as any of the other spruces. It is used some for reforestation in the northeast.
Foodplant / parasite
hypophyllous telium of Chrysomyxa abietis parasitises live leaf of Picea rubens
Remarks: season: 3-5
Associated Forest Cover
5 Balsam Fir
12 Black Spruce
17 Pin Cherry
18 Paper Birch
21 Eastern White Pine
22 White Pine-Hemlock
23 Eastern Hemlock
25 Sugar Maple-Beech-Yellow Birch
30 Red Spruce-Yellow Birch
31 Red Spruce-Sugar Maple-Beech
33 Red Spruce-Balsam Fir
34 Red Spruce-Fraser Fir
35 Paper Birch-Red Spruce-Balsam Fir
37 Northern White-Cedar
60 Beech-Sugar Maple
107 White Spruce
108 Red Maple
Some of the shrubs associated with red spruce are: blueberry (Vaccinium spp.), hobblebush (Viburnum lantanoides), witherod (V. cassinoides), rhodora (Rhododendron canadense), lambkill (Kalmia angustifolia), mountain-holly (Nemopanthus mucronata), speckled alder (Alnus rugosa), red raspberry (Rubus idaeus var. strigosus), creeping snowberry (Gaultheria hispidula), wintergreen (G. procumbens), fly honeysuckle (Lonicera canadensis), gooseberry (Ribes spp.), witch-hazel (Hamamelis virginiana), downey serviceberry (Amelanchier arborea), beaked hazel (Corylus cornuta), and Canada yew (Taxus canadensis).
A number of mosses and herbs are also found growing in red spruce forest types. Certain mosses, herbs, and shrubs, however, have been shown to be related to site quality of red spruce (22). The three main associations, Hylocomium/Oxalis, Oxalis/Cornus, and Viburnum/0xalis, in that order, indicate increasing site productivity and increasing hardwood competition. Similar site types in the higher elevations of the Appalachian Mountains of North
Carolina include Hylocomium/Oxalis on north-facing slopes above 1520 m (5,000 ft), Oxalis/Dryopteris at high elevations and all exposures, and the best site type for red spruce and Fraser fir, Viburnum/Vaccinium/Dryopteris (47).
The Oxalis/Cornus association is considered the best for growing conditions in the northern part of the range. On these sites the soil is rich enough for red spruce but not fertile enough for the tolerant hardwoods to offer serious competition (22).
Diseases and Parasites
The most important insect enemy of red spruce is the spruce budworm, Choristoneura fumiferana. Although red spruce is much less vulnerable to damage than balsam fir or white spruce, largely due to later bud flushing in the spring (3), much damage and mortality occur in stands containing large quantities of mature balsam fir. Blum and McLean (4) suggest that factors such as stand age, species composition, density, and vigor contribute to the vulnerability of spruce-fir stands to budworm damage and suggest steps to alleviate damage. Additional, detailed information may also be found in Sanders, et al. (42) for spruce-fir stands in the Northeast, the Lake States, and Canada.
The eastern spruce beetle, Dendroctonus rufipennis, damages mature trees of red spruce. Two species of sawflies, the European spruce sawfly, Diprion hercyniae, and the native yellowheaded spruce sawfly, Pikonema alaskensis, have severely defoliated red spruce in localized areas (22). The eastern spruce gall adelgid, Adelges abietis, can be a serious pest on spruce when abundant. The pine leaf adelgid, Pineus pinifoliae, forms unsightly but relatively harmless conelike galls on red and black spruce (Picea mariana), which are alternate hosts (46).
Red spruce has few diseases. Needle cast caused by Lirula macrospora may result in severe defoliation of the lower crown and a subsequent reduction of growth. Phellinus pini and Phaeolus schweinitzii, the most destructive of red spruce wood-rotting fungi, are usually confined to overmature or damaged trees. Climacocystis borealis causes butt rot in overmature trees (22). Trees are occasionally attacked by Armillaria mellea and Inonotus tomentosa.
All along the eastern Appalachian mountain chain, from the New England states to Georgia, growth has declined in high-elevation red spruce since the 1960's (25). In recent years, this decline has been accompanied by increased mortality and crown damage in high-elevation red spruce. Apparently, no significant natural biotic or abiotic causal agents have been identified, although it has been hypothesized that interaction among naturally occurring insect and disease factors and anthropogenic air pollutants, or air pollutants acting alone, are at the root of the problem. Sulphur dioxide (S02), nitrogen oxides (NOx), and volatile organic compounds are the pollutants of primary concern; secondary pollutants such as ozone and nitric and sulfuric acids are also believed to be important factors (29).
Growth decline and mortality in low-elevation red spruce in northern New England, while increasing in some areas, appear to be within the normal ranges for trees and forests of various ages, compositions, and density. However, some foliar symptoms have been detected in both red spruce and white pine, particularly from ozone exposure.
Red spruce is occasionally infected with eastern dwarf mistletoe, Arceuthobium pusillum, a parasite causing growth reduction, tree mortality, and degradation of wood quality (24).
Mice and voles have been found to consume and store significant amounts of spruce seeds in preference to those of balsam fir, suggesting one reason for the low ratio of spruce to fir seedlings commonly found in naturally regenerated stands (1,23). Wildlife damage to the terminal buds of young spruce, presumably by birds, also has been noted (2). Some injury and mortality are also caused occasionally by porcupines, bears, deer, and yellow-bellied sapsuckers (11). Red squirrels clip twigs and terminals and eat reproductive and vegetative buds (41).
Fire Management Considerations
Some managers believe that prescribed fire may be a useful silvicultural
tool for managing red spruce on some sites. On such sites, the exposed
mineral soil must have plentiful moisture, soil temperatures must be
moderate, and competition must be minimal . In general, however,
fires in red spruce habitat are of little silvicultural value .
Slash burning following logging kills advance reproduction and creates
rank postfire vegetation that delays any new seedling establishment
The fire management plan for Acadia National Park, Maine, dictates the
suppression of natural fires. Prescribed fires may be used on occasion
to reduce fuels . Patterson and others  estimated fuel loadings
for a number of stands in Acadia National Park that contained red
spruce. They concluded that fire exclusion was probably resulting in
increased fuel loads.
Alexander  compiled slash fuel indices for red spruce and compared
actual fire spread, intensity, and slash and organic layer depletions
with those predicted by the Canadian Forest Fire Danger Rating System.
Freeman and others  developed equations to determine average crown
weight per tree as a function of tree height and diameter for use in a
method to predict slash weight after logging red spruce.
Plant Response to Fire
Red spruce does not sprout. Seed germination is greater on burned areas
with exposed mineral soil than in duff; mortality, however, is also
greater due to increased surface temperature and drought .
Burned red spruce or spruce-fir stands are initially restocked by aspen
(Populus spp.) or birch (Betula spp.) via wind-disseminated seed; paper
birch (Betula papyrifera)-aspen stands are particularly diagnostic of
fire in upland red spruce forests . Red spruce seedlings appear a
few years after fire, developing as an understory in the aspen-birch
complex, and eventually penetrate the overstory after 50 or 60 years.
Birch and aspen become decadent after 75 to 80 years and red spruce or
red spruce and balsam fir regain dominance if left undisturbed
[49,52,65]. On better sites, northern hardwoods, chiefly sugar maple
and American beech, may replace red spruce, and in some areas, balsam
fir will dominate the late postfire succession. Postharvest/postfire
restocking by red spruce is extremely slow where the organic layers are
destroyed by severe fire (particularly where harvest has been heavy)
In Nova Scotia, mature spruce forests have few herbs and shrubs in the
understory. After a fire, herbs increase in the first 6 years and
dominate for 40 or more years while conifers slowly establish .
After fire in the southern Appalachians, blackberry (Rubus ursinus) and
red raspberry colonize the site. Pin cherry and yellow birch follow.
Blackberry and raspberry are too competitive for red spruce and must be
shaded out by the hardwoods before red spruce can establish .
In West Virginia, postlogging and postfire succession in red spruce
forests follows a similar pattern: ferns and raspberry are followed by
other shrubs, then hardwoods (particularly hawthorn [Crataegus spp.]),
and eventually spruce. In many areas, this successional pattern has
been extremely slow; heaths or barrens form that do not appear as if
they will ever return to forest . Martin  studied
postlogging/postfire succession in Nova Scotia and found that red spruce
was present on most sites after the second postfire year, becoming more
numerous and dominant in the later seres. He concluded that repeated
heavy cuttings and light fires on the poorer soils of the southern
upland of Nova Scotia encourages the invasion of heath plants, which
limits the rate and amount of tree regeneration.
Immediate Effect of Fire
Red spruce is easily killed by fire . Surface or ground fires that
consume the litter and organic layers covering the superficial roots of
red spruce are almost certain to severely injure the roots . Fire
kills mature trees by exposing roots, subjecting the tree to water
stress and/or windthrow, which may result in the eventual death of the
Tree without adventitious-bud root crown
Secondary colonizer - off-site seed
Red spruce forests persist without fire. Red spruce is easily killed by
fire due to its thin bark, shallow roots, flammable needles, and lack of
self-pruning [9,23,39]. Its slow early growth rate delays the formation
of a corky layer, which increases the fire susceptibility of young trees
. In a study based on a survey of foresters, Starker  rated the
fire resistance of 22 New England tree species based on fire mortality
and fire avoidance (occurrence in habitat that does not burn very
often). Red spruce was not resistant in terms o fire mortality but
moderately or very resistant in terms of fire avoidance, and was ranked
Red spruce habitat is subject to few fires; fires that occurred in
presettlement times were usually of low severity . Saunders 
noted that old-timers claimed that forest fires would stop when they
reached the spruce-fir forest boundary. Electrical storms are common in
this area but are usually accompanied by sufficient rain, and fuels are
usually moist . Severe surface fires probably occurred
infrequently, during periods of prolonged drought, and usually affected
forests that were breaking up due to wind, ice storm damage, or similar
events that generate surface fuels [25,32,60,61,87].
The estimated natural fire return intervals for the northeastern United
States and adjacent Canada range from 330 to 3,300 or more years
[25,32,51,52,84]. Estimates of natural fire frequency have been
complicated by human activities. Logging in these forests has resulted
in an increase in fire frequency and intensity, particularly in logging
slash [18,32,52]. The catastrophic fires of the 19th and 20th centuries
can be attributed to human activities [21,32,52]. However, even with
the increase in fires due to human activity, most fires are small and
quickly suppressed. There should be sufficient time between fires for
red spruce to regain dominance on most sites unless deliberately and/or
It has been suggested that, in presettlement forests, the increase of
dead fuels following spruce budworm outbreaks increased the likelihood
of fire [21,25,32]. Such outbreaks are more common in
balsam-fir-dominated forests than in red-spruce-dominated forests, but
the two species usually occur together, in varying proportions.
Before settlement by Europeans, forests in northern New England, the
Adirondack Mountains, and the hillier sections of southern New England
and Pennsylvania were not deliberately burned by Native Americans as
were other areas in the northeastern United States .
More info for the terms: climax, cover, hardwood, tree
Facultative Seral Species
On shallow, acidic, glacial till soils, red spruce is considered climax.
It is usually subclimax on fertile, well-drained slopes and on abandoned
fields and pastures where is is replaced by shade-tolerant hardwoods
such as sugar maple and beech. Other types, such as red spruce-balsam
fir and red spruce-yellow birch are usually climax .
Red spruce is tolerant of shade. Seedlings of red spruce can establish
in as little as 10 percent of full sunlight, but for optimum growth, at
least 50 percent of full sunlight is needed [9,75,81]. Growth tends to
be suppressed in shade, but such suppression can persist for many years
without killing the tree. For example, suppressed understory
individuals may be 4 to 5 feet (1.2-1.5 m) tall, and be more than 50
years old. In comparison, open-grown red spruce can reach sawtimber
size at 50 years [9,29].
Red spruce responds to canopy removal even after many years of
suppression. The taller and older a seedling or sapling is, the greater
is its response to release, up to about 55 years of age after which
response to release starts to decline. However, the amount of response
does not revert to seedling levels until the tree is around 100 years of
age. Umbrella-shaped saplings 40 to 80 years old that have been
suppressed will respond to release after a delay of several years, and
in fact have an advantage because they are taller than smaller,
healthier saplings which respond more quickly to canopy opening. More
than half of mature red spruce second growth arises from larger but
suppressed advance growth, as opposed to having arisen from small
advance growth or new seedlings . Upon release, 60-year-old red
spruce growth exceeds that of same-age balsam fir and therefore tends to
dominate the canopy .
Leak  defined red spruce in New Hampshire as a dominating climax
species on shallow, dry, wet, or poorly areated soils; it is a minor
component in young stands but increases markedly over time until it is a
canopy dominant. He estimated that, if undisturbed, red spruce can
reach densities of 70 to 80 percent in a minimum of 250 years. Red
spruce is a long-lived species and, once established, persists as a
dominant for a long time.
Davis  observed young spruce-fir stands in coastal Maine originating
in open sites and as the understory to early seral hardwoods such as
paper birch. The young, open-grown stands may be dominated by white
spruce, red spruce, or balsam fir in any proportions. A spruce-fir
stand originating as understory tends to be dominated by red spruce
and/or balsam fir, though white spruce is often present. Moore 
found red spruce forests to be even-aged in groups, indicating that
establishment and/or canopy achievement tends to occur in openings.
Red spruce and red spruce-fir cover types are self-maintaining. Stand
composition may vary with stand age. Both red spruce and its two fir
associates (balsam and Fraser) are shade tolerant, and both spruce and
fir reproduction are found under spruce-fir canopies [6,16]. In the
Catskill Mountains of New York, balsam fir reproduction predominated
under both spruce and balsam fir stands. Both red spruce and balsam fir
reproduction occurred at low densities under hardwood stands (mostly
yellow birch) . McIntosh and Hurley  do not believe that red
spruce forests form a self-perpetuating climax in this area. Their
conclusion may be biased, however, since balsam fir outcompetes red
spruce in early stages, but is usually overtopped or outcompeted by red
spruce in more mature forests . Flieger  described 350-year-old
stands of red spruce which were characterized by irregular stocking and
variable crown heights and widths, with at least two age classes
apparent. Most virgin red spruce forests are uneven-aged, indicating
that the forests did no originate following stand-destroying
disturbances, and that red spruce is able to reproduce under its own
Red spruce reproduces exclusively by seed. The first cone crop is
usually produced when the crown first reaches direct light [27,39].
Therefore, red spruce can bear cones as early as 15 to 20 years of age;
cone production peaks about 15 years later. In dense, even-aged stands,
full cone crops are rare until the trees are 40 to 50 years old .
Good seed crops are produced every 3 to 8 years, with light crops in
intervening years. Cones are dropped shortly after they are mature .
The seeds are wind or rain disseminated. The maximuim distance for
dispersal by wind is approximately 201 feet (61 m) . Seeds do not
exhibit dormancy. Most germinate the spring following dispersal;
occasionally germination will occur in the fall soon after seeds drop
from the tree. Seeds are usually not viable after 1 year. Germination
is largely controlled by moisture availability. Seeds will germinate in
almost any medium except sod. Seeds that germinate in thick duff are
subject to overheating and/or drought mortality. Drought and
frost-heave are the major causes of seedling mortality the first year
Successful reproduction appears to depend more on seedling survival than
on germination requirements . Seedling establishment is usually best
on shallow, less fertile soils that discourage competitive hardwoods
. The primary roots of red spruce seedlings do not penetrate litter
and forest duff to any depth . Red spruce seedlings have a root
system of finely branched rootlets and no strong laterals; they depend
entirely on the humus for nutrients and water .
Growth Form (according to Raunkiær Life-form classification)
Reaction to Competition
The species' chief competition comes from balsam fir and hardwoods that produce heavy shade, like beech and maple. Competition from aspen, birch, and other thin-crowned species is not so severe. Red spruce prunes itself about as well as most softwoods in dense stands. As much as one-third of the live crown may be pruned artificially without seriously affecting radial growth (5).
A number of studies have demonstrated the ability of red spruce to respond to release after many years of suppression. The vigor of this response does decline somewhat with age, however, and older trees may require about 5 years to recover before showing accelerated growth (7). Reduction of growth to about 2.5 cm (1 in) of diameter in 25 years, for a duration of 100 years, represents about the limit of suppression for red spruce. Many of its associated tree species such as balsam fir and hemlock may outgrow red spruce after release (22).
Red spruce may be grown successfully using even-age silvicultural prescriptions (11,12). Red spruce is very shallow-rooted, however, making it subject to windthrow, a major silvicultural constraint in the management of the species. As a general rule, it is recommended that no more than one-fourth to one-half of the basal area be removed in the partial harvest of a spruce-fir stand, depending on site, to avoid excessive windthrow damage.
Most of the major forest cover types previously listed in which red spruce is a component are considered either climax or subclimax.
Life History and Behavior
Red spruce vegetative buds begin growth from May 26 to June 3 .
Needles are shed early in summer . Reproductive cones open in late
April to early May [29,72]. Red spruce cones mature the first autumn
from mid-September to mid-October [29,39]. Dissemination of seeds
begins soon after cones are ripe and continues until March .
Adequate moisture is the chief factor controlling germination of red spruce. Germination takes place on almost any medium (mineral soil, rotten wood, or shallow duff) except sod. Mineral soil is an excellent seedbed for germination. Generally ample moisture is available and soil temperatures are moderate. Litter and humus are poorer seedbeds because they are likely to be hotter and drier than mineral soil (11). On thicker duff, germination may be poor also because moisture conditions are less favorable. Temperatures of 20° to 30° C (68° to 86° F) are generally favorable for germination. Seeds will not germinate satisfactorily at temperatures below 20° C (68° F) and are permanently injured by long exposure to temperatures higher than 33° C (92° F) (22).
Germination and initial establishment proceed best under cover. Seedlings can become established under light intensities as low as 10 percent of full sunlight; however, as they develop, they require light intensities of 50 percent or more for optimum growth. Seedlings starting in the open undergo heavy mortality when soil surface temperatures reach 46° to 54° C (115° to 130° F) even for a short time (11). Drought and frost heaving are major causes of mortality the first year. Crushing by hardwood litter and snow are also causes of seedling mortality. Winter drying in some years and locations can cause severe leader damage and dieback.
Natural reproduction depends more on seedling survival than on requirements for germination. Spruce seedlings have an exceptionally slow-growing, fibrous, shallow root system. Consequently, a critical factor in their survival and establishment is the depth of the 01 organic layers of the soil profile. When the combined thickness of these layers exceeds 5 cm (2 in), spruce seedlings may not reach mineral soil and the moisture necessary to carry them through dry periods. Red spruce seedlings and the commonly associated balsam fir seedlings are similar in many ways and are controlled by the same factors, but as a rule spruce is the weaker, slower growing species during the establishment period (22).
Seedlings that have attained a height of about 15 cm (6 in) can be considered established. Once established, their early growth is determined largely by the amount and character of overhead competition. Dense growth of bracken (Pteridium aquilinum), raspberry, and hardwood sprouts are the chief competition for seedlings on heavily cutover lands; but red spruce survives as much as 145 years of suppression and still responds to release (11,39).
Compared to its associates, red spruce is one of the last species to start height growth in the spring, usually beginning the first week in June and ending 9 to 11 weeks later. Radial growth usually begins about the second week of June and continues through August (22).
Seed Production and Dissemination
Red spruce seeds fall about 1.2 m (4 ft) per second in still air; the following formula determines distance of travel for wind- disseminated spruce seeds at various heights (47):
D = Sh (1.47v)
Where D = distance in feet which seed will travel, S = number of seconds required for seed to fall from a height of h (ft) on a tree, and v = velocity of the prevailing wind in miles per hour.
Randall (37), in a study of seed dispersal into clearcut areas, stated that at a distance of 100 m (5 chains or 330 ft) from the timber edge, the number of spruce seeds trapped were more than adequate for regeneration in a good seed year and adequate in an average year. Most of the spruce in the surrounding stands was red spruce.
Flowering and Fruiting
Growth and Yield
The rate of red spruce's growth is strongly influenced by light conditions. Although trees can live in dense shade for many years, once they reach sapling to pole stage nearly full sunlight is beneficial. Understory trees no more than 1.2 or 1.5 m (4 to 5 ft) tall may be more than 50 years old, whereas trees of the same age in the open may be approaching small sawtimber size (22).
Under favorable conditions, red spruce may reach an average d.b.h. of 10 cm (4 in) and height of 7 m (23 ft) in 20 years, and be over 23 cm (9 in) in d.b.h. and 19 m (62 ft) tall in 60 years (22).
Diameter growth of red spruce has been related to vigor, live crown ratio (ratio of live crown to total height), live crown length, and initial diameter at breast height (6,32). High vigor red spruce with a live crown ratio of 0.5 or better averaged 4.3 cm (1.7 in) of diameter growth in 10 years. Growth rates of trees with smaller crown ratios and less vigorous trees decreased progressively to an average of 0.8 cm (0.3 in) in 10 years for trees of low vigor or with crown ratios smaller than 0.4 (22). A tree classification for red spruce is shown in table 1 (11).
Table 1- Classification of red spruce trees (11). Tree class
Crown class Live
Average 10-year growth in d.b.h. cm in A, superior
Intermediate 0.6+ 4.6 1.8
B, good I
Intermediate 0.3 to 0.5 3.3 1.3 C, acceptable II Overtopped
0.6+ 2.3 0.9 D, inferior Intermediate 0.3 to 0.5 1.5 0.6 E, undesirable
All others 0.3+
0.3 or less 0.5 0.2 ¹Ratio of live crown to total height. In one study (40), average net annual growth in softwood stands (66 to 100 percent softwood species) that can be expected from stands receiving minimal silvicultural input was found to be about 3.5 m³/ha (50 ft³/acre). In mixed-wood stands (21 to 65 percent softwood species) this dropped to about 2.8 m³/ha (40 ft³/acre), although the majority of the growth was contributed by softwoods. A further breakdown of the data shows the contributions of spruce, most of which was assumed to be red spruce, to be 51 percent in softwood stands and 39 percent in mixed-wood stands.
Yields per acre, in total volumes of all trees larger than 1.5 cm (0.6 in) in d.b.h. (inside bark and including stump and top but not butt swell), are given in table 2 (33).
Table 2- Yield of red spruce by age class and site index (adapted from 33) Site index¹
Age 12.2 m
or 40 ft 15.2 m
or 50 ft 18.3 m
or 60 ft 21.3 m
or 70 ft yr m³/ha 20 6 8 11 14 40 94 132 164 200 60 244 335 422 507 80 308 424 533 640 100 332 456 575 691 yr ft³/acre 20 80 120 160 200 40 1,350 1,890 2,350 2,850 60 3,490 4,780 6,030 7,240 80 4,400 6,060 7,610 9,150 100 4,740 6,250 8,210 9,870 ¹Base age 50 years when age is measured at d.b.h.- total tree age is estimated to be 65 years at the time. These yields are normal yields from even-aged stands growing primarily on old fields. Therefore, they are higher than yields that might be expected from more irregular stands such as those developing after cutting (22).
Site index has not been of great utility in rating the potential productivity of spruce-fir sites because of the tolerance of the species and its ability to survive in a suppressed state. Site index at base age 50 years is as good a measure of productivity as any of several growth functions, however (39). Recently, polymorphic site index curves were developed for even-aged spruce and fir stands in northern Maine; they should be valuable for estimating site productivity (20).
Other yield tables for the Northeast (48) take into consideration stand density, composition, and time since cutting. These tables give merchantable volume of spruce and fir combined in trees 15.2 cm (6 in) in d.b.h. and larger from a 0.3 m (1 ft) stump to a 7.6 cm (3 in) top, diameter inside bark, and are somewhat conservative. Yields of merchantable volume for different stand densities from 10 to 50 years after cutting, where 90 percent of the trees are spruce and fir growing on predominantly softwood sites, are given in table 3.
Table 3- Merchantable yield of red spruce (adapted from 48) Density index (regional average 100) Years since cut 50 100 150 m³/ha 10 17.1 24.4 29.5 20 29.8 37.7 43.3 30 43.5 52.0 58.0 40 58.1 67.3 73.4 50 73.8 83.1 89.7 ft³/acre 10 245 349 422 20 425 539 618 30 622 743 828 40 830 961 1,049 50 1,054 1,187 1,281 The development of stand projection growth models that permit computer simulation of red spruce tree growth for various management practices and silvicultural treatments over a range of stand conditions has flourished in recent years. For example, the model FIBER was developed in the Northeast (43) for spruce-fir, northern hardwood and a range of Mixedwood forest types between the two. Such models have proved very useful for forest management planning.
In recent years, interest in total biomass yield and productivity has increased, and in the future is likely to become more important in management considerations. As an example, above-ground biomass and productivity values of typical red spruce stands in Canada are given in table 4 for stands in a steady state, across a moisture regime catena (17).
Table 4- Aboveground biomass and annual production of all tree components and foliage for red spruce at latitude 45° 30' N. (adapted from 17) Moisture regime
Production t/ha tons/acre t/ha tons/acre Dry 121.3 54.1 4.5 2.0 Fresh 263.2 117.4 8.7 3.9 Moist 461.3 205.8 9.9 4.4 Wet 164.1 73.2 3.8 1.7
Molecular Biology and Genetics
Crossability of P. rubens with P. omorika is good with P. mexicana and P. likiangensis moderate; with P. mariana, P. orientalis, P. maximowiczii, and P. glehnii fair to poor; and with P. koyamai, P. sitchensis, P. x lutzii, and P. glauca very poor. Several species fail to cross with P. rubens (15,16,18,19).
Hybrids between P. rubens and P. mariana occur to some extent in nature, but parental species remain phenotypically pure in their characteristic habitats (15,30,31,34,35).
Barcode data: Picea rubens
Statistics of barcoding coverage: Picea rubens
Public Records: 7
Specimens with Barcodes: 8
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 (e.g. threatened or endangered species, state noxious status, and wetland indicator values).
Pests and potential problems
Red spruce has several insect enemies, the most important being spruce budworm. Budworm damage may be heavy in stands that contain a large percentage of balsam fir. Some stands of red spruce may be susceptible to damage by the eastern spruce beetle, European spruce sawfly and yellow-headed spruce sawfly. Disease problems are minor in management of red spruce.
The overall health of red spruce stands seems to be declining due to pollution factors. Weakened trees are more susceptible to insects and disease.
Silviculture: Various silvicultural systems may be used to manage red
spruce. Single tree selection, group selection, shelterwood, and strip
clearcut are all practical harvesting methods. Red spruce is subject to
windthrow; partial cuttings are recommended not to exceed half of the
basal area, and a lighter harvest is usually better. Seed tree cuts are
not recommended [6,9]. Frank and Blum  recommend a selection
silviculture where net growth is maximized by a 10-year, intensive
selection system. Clearcuts are contraindicated for many soil types and
fertility levels .
Postharvest red spruce regeneration is entirely dependent on advance
reproduction. If seedlings are not present at the time of logging, any
new spruce seedlings will be quickly overtopped and suppressed by faster
growing hardwoods . The presence of leaf litter may beenefit for
regeneration. Harvesting during the dormant season or allowing
harvested trees to dry on site has been recommended to increase litter
. Loucks  noted that in the Maritime Provinces of Canada, red
spruce regeneration is usually good following partial cuts but may be
lacking in clearcuts.
The extent of red spruce forests has decreased following extensive
logging practices and subsequent fire . In the mountains of central
West Virginia, it is estimated that approximately 500,000 acres (200,000
ha) of red spruce present in the late 19th century had been reduced to
less than 60,000 acres (24,000 ha) by 1975, and as little as 17,500
acres (7,000 ha) in 1978 [10,73].
Management for wildlife: Harvest practices have an effect on the
resulting stand structure, and therefore on the numbers and species of
birds that use red spruce habitats. Crawford and Titterington 
identified five seral stages and the corresponding bird species, and
made associated recommendations for management of spruce-fir stands.
They also determined that spruce budworm infestation increases both the
number and diversity of birds. Dense, young stands of red spruce
support a higher population of birds but with less diversity than in
Insects and disease: Red spruce is relatively free from insects and
diseases until it is mature. Mature trees are susceptible to the
following insects: spruce budworm (Choristoneura fumiferana), eastern
spruce beetle (Dendroctonus rufipennis), European spruce sawfly (Diprion
hercyniae), yellowheaded spruce sawfly (Pikonema alaskensis), and
eastern spruce gall adelgid (Adelges abietis) [9,22,23,30]. Diseases of
red spruce have been detailed [9,22,23,30,47].
Red spruce decline: Throughout its range, growth rates of red spruce
have declined and mortality has increased . This decline is
apparently more severe at higher elevations, in older stands, and on
more exposed sites. This decline is not limited to red spruce; balsam
fir and associated white and black spruce appear to be affected also
. A number of studies on the causes of red spruce decline have
failed to make a definitive case for any single cause. There may be no
single cause or the complexity of the situation may not lend itself to a
clear cause-effect relationship [36,42,47]. The combination of climatic
stress and atmospheric pollution is probably the major cause of this
decline, according to a number of researchers [19,36,41,42]. Numerous
other causes have been proposed as well, including a natural cycle of
dieback and recovery [3, 36,]. A survey of the extent and identifiable
causes of mortality and decline was published in 1985 .
Red spruce has not generally received intensive management in the northeast. It can be harvested by partial cutting or clear cutting depending upon local markets and silvicultural conditions. Weeding and releasing, if needed, should be done at an early age, 10 to 15 years.
Relevance to Humans and Ecosystems
Red spruce provides thermal and loafing cover for spruce grouse in
Value for rehabilitation of disturbed sites
West Virginia, primarily at high elevations, but it is of limited value
for this purpose .
Importance to Livestock and Wildlife
voles consume and store significant amounts of spruce seeds, preferring
red and white spruce to balsam fir . Birds (particularly crossbills
or grosbeaks) will clip the terminal buds of young spruce, as will
porcupines, bears, snowshoe hares, and, rarely, deer [7,55,78]. Red
squirrels clip twigs and terminal buds and also eat reproductive and
vegetative buds [7,72].
In the southern part of its range, red spruce forests are used by only a
few wildlife species. Many of these species are usually only found
farther north, such as snowshoe hare, wood warblers and other songbirds,
rodents, and salamanders .
Wood Products Value
northeastern United States. The wood is light in weight, straight
grained, and resilient. It is used for paper, construction lumber, and
is highly preferred for musical instruments [9,29].
Other uses and values
Forest cover types that include red spruce support a wide variety of wildlife. They are particularly important as winter cover for deer and, to a certain extent, moose. Small game includes ruffed grouse, snowshoe hare, and woodcock. Many song birds and fur bearers also frequent these forest types (44).
A unique use of red spruce was spruce gum, an exudate that accumulates on trunk wounds. This was the raw material for a flourishing chewing-gum industry in Maine during the last half of the 19th century and early years of this century (21).
Red spruce is one of the most important forest trees in the northeast. The wood is light, soft, narrow-ringed and faintly tinged with red. It is the most common species of eastern spruce lumber. Because of its resonance, it is especially adapted to sounding boards in musical instruments. It makes up a large percentage of spruce pulpwood produced in the northeast. It is used as a Christmas tree also.
Red spruce provides food and cover for various mammals and birds. The spruce grouse feeds on the buds and foliage; red squirrels eat buds and seeds; varying hare browse twigs and foliage; porcupines feed upon the bark. Red spruce seeds make up 25 to 50 percent of the diet of white-winged crossbills. Red spruce can be an important cover tree in northern New England deer yards.
Picea rubens (red spruce) is a species of spruce native to eastern North America, ranging from eastern Quebec to Nova Scotia, and from New England south in the Adirondack Mountains and Appalachians to western North Carolina.
This species is also known as yellow spruce, West Virginia spruce, eastern spruce as well as he-balsam.
Red spruce is a perennial, shade-tolerant, late successional. coniferous tree which under optimal conditions grows to 18–40 metres (59–131 ft) tall with a trunk diameter of about 60 centimetres (24 in), though exceptional specimens can reach 46 m (151 ft) tall and 30 cm (12 in) diameter. It has a narrow conical crown. The leaves are needle-like, yellow-green, 12–15 millimetres (0.47–0.59 in) long, four-sided, curved, with a sharp point, and extend from all sides of the twig. The bark is gray-brown on the surface and red-brown on the inside, thin, and scaly. The wood is light, soft, has narrow rings, and has a slight red tinge. The cones are cylindrical, 3–5 centimetres (1.2–2.0 in) long, with a glossy red-brown color and stiff scales. The cones hang down from branches.
Red spruce grows at a slow to moderate rate, lives for 250 to 450+ years, and is very shade-tolerant when young. It is often found in pure stands or forests mixed with eastern white pine, balsam fir, or black spruce. Along with Fraser fir, red spruce is one of two primary tree types in the southern Appalachian spruce-fir forest, a distinct ecosystem found only in the highest elevations of the Southern Appalachian Mountains. Its habitat is moist but well-drained sandy loam, often at high altitudes. Red spruce can be easily damaged by windthrow and acid rain.
Notable red spruce forests can be seen at Gaudineer Scenic Area, a virgin red spruce forest located in West Virginia, the Canaan Valley, Roaring Plains West Wilderness, Dolly Sods Wilderness, Spruce Mountain and Spruce Knob all also in West Virginia and all sites of former extensive red spruce forest. Some areas of this forest, particularly in Roaring Plains West Wilderness, Dolly Sods Wilderness as well as areas of Spruce Mountain are making a rather substantial recovery.
Red spruce is used for Christmas trees and is an important wood used in making paper pulp. It is also an excellent tonewood, and is used in many higher-end acoustic guitars and violins as well as musical soundboard. The sap can be used to make spruce gum. Leafy red spruce twigs are boiled as a part of making spruce beer. Also it can be made into spruce pudding. It can also be used as construction lumber and is good for millwork and for crates.
Like most trees, red spruce is subject to insect parasitism. Their insect enemy is the spruce budworm although it is a bigger problem for white spruce and balsam fir. Other issues that have been damaging red spruce has been the increase in acid rain and current climate change.
The Central Appalachian Spruce Restoration Initiative (CASRI) seeks to unite diverse partners with the goal of restoring historic red spruce ecosystems across the high-elevation landscapes of central Appalachia.
The partners that make up this diverse group are Appalachian Mountain Joint Venture, Appalachian Regional Reforestation Initiative, Canaan Valley National Wildlife Refuge, Natural Resources Conservation Service, The Mountain Institute, The Nature Conservancy, Trout Unlimited, U.S. Forest Service Northern Research Station, U.S. Forest Service Monongahela National Forest, West Virginia Division of Natural Resources, West Virginia Division of Forestry, West Virginia Highlands Conservancy, West Virginia State Parks, and West Virginia University.
Prior to the late 1800s there were 600,000 ha of red spruce in West Virginia. In the late 1800s and early 1900s, a vast amount of logging began in the state and the number of red spruce dwindled down to 12,000 ha. Restoration silviculture is being used to help restore the population of the lost red spruce.
|Wikimedia Commons has media related to Picea rubens.|
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- Gymnosperm Database: Picea rubens
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- "Red Spruce". USDA NRCS. Retrieved 26 February 2014.
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- Peter White, "Boreal Forest," Encyclopedia of Appalachia (Knoxville, Tenn.: University of Tennessee Press, 2006), pp. 49-50.
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- Blum, Barton. "Red Spruce". Encyclopedia of Life. Retrieved 27 February 2014.
- Houle, Daniel (2012). "Compositional vegetation changes and increased red spruce abundance during the Little Ice Age in a sugar maple forest of north-eastern North America". Plant Ecology 213 (6): 1027–1035. doi:10.1007/s11258-012-0062-0. Retrieved 27 February 2014.
- Burks, Evan (2010), "Return of the Red Spruce", Wonderful West Virginia; Vol. 74, No. 12 (Dec issue), pp 6-11.
- Bove, Jennifer. "Appalachian Red Spruce Forest". Retrieved 27 February 2014.
- Rentch, James; T. Schuler; M. Ford; G. Nowacki (September 2007). "Red Spruce Stand Dynamics, Simulations, and Restoration Opportunities in the Central Appalachians". Restoration Ecology 15 (3): 440–452. doi:10.1111/j.1526-100x.2007.00240.x. Retrieved 27 February 2014.
Red spruce ( Picea rubens ) is the provincial tree of Nova Scotia.
Names and Taxonomy
are no subspecies, varieties, or forms [48,64].
Natural hybrids with black spruce (P. mariana) have been reported
West Virginia spruce
Picea australis Small
Picea nigra var. rubra Engelmann.