Robert M. Frank
Balsam fir (Abies balsamea) is one of the more important conifers in the northern United States and in Canada. Within its range it may also be referred to as balsam, Canadian balsam, eastern fir, and bracted balsam fir. It is a small to medium-sized tree used primarily for pulp and light frame construction, and it is one of the most popular Christmas trees. Wildlife rely extensively on this tree for food and shelter.
Balsam fir is a small to medium sized coniferous tree. Growth occurs in whorls of branches surrounding an upright leader or terminal, making a symmetrical tree with a broad base and narrow top. It is relatively short-lived and is considered a sub-climax type species in the New England states, but may be a climax type in the zone below timberline.
Needles are 3/4 to 1 inch long, flat, and often strongly curved. Twigs with needles have a generally flattened appearance. Both male and female flowers are found on the same branch. Cones are 2 to 4 inches long, purplish in color, and stand erect on branches (as do those of all true firs). There are about 60,000 seeds in a pound. The bark is smooth, thin, and grayish, distinguished by soft blisters containing a clear, odiferous resin known as Canadian balsam.
Regularity: Regularly occurring
Regularity: Regularly occurring
occurs from Newfoundland west across northern Quebec, northern Ontario,
central Manitoba, and Saskatchewan to northwestern Alberta, south about
400 miles (640 km) to central Alberta, southeast to northern Minnesota
and Wisconsin, and east to New England . In the United States,
scattered populations occur in southern Minnesota, southern Wisconsin,
northeastern Iowa, Pennsylvania, West Virginia, and northern Virginia.
The two varieties are distributed as follows :
var. balsamea - from Newfoundland and Labrador west to northeastern
Alberta and south to Minnesota, Wisconsin, southern
Ontario, northern Pennsylvania, New York, and New
England. It is local in northeastern Iowa.
var. phanerolepis - from Newfoundland and Labrador to Ontario and Maine
and in the high mountains of New Hamphire, Vermont,
and New York. It is also common in the higher
mountains of Virginia and West Virginia.
Occurrence in North America
VA WV WI AB LB MB NB NF NS ON
PE PQ SK
In the United States, the range of balsam fir extends from extreme northern Minnesota west of Lake-of-the-Woods southeast to Iowa; east to central Wisconsin and central Michigan into New York and central Pennsylvania; then northeastward from Connecticut to the other New England States. The species is also present locally in the mountains of Virginia and West Virginia (23,30).
Balsam fir grows from sea level to within 15 to 23 m (50 to 75 ft) below the 1917 m (6,288 ft) summit of Mount Washington in the White Mountains of New Hampshire. At this elevation prostrate balsam fir is found in sheltered areas (1).
- The native range of balsam fir.
Distribution and adaptation
The soils on which balsam fir grows range from silt loams developed from lake deposits to stony loams derived from glacial till. Fir will grow, but comparatively slowly, on gravelly sands and in peat bogs. It grows on soils of pH ranging from 4.0 to 6.0. It is generally found in areas with a cold moist climate and with 30 inches or more of annual precipitation. Fir is subject to windthrow, especially on shallow wet soils. Because of its thin bark, shallow root system, and flammable needles, balsam fir is easily killed by fire.
Balsam fir is distributed throughout the Northeast and upper Midwest. For a current distribution map, please consult the Plant Profile page for this species on the PLANTS Website.
Balsam fir is a native, coniferous, evergreen, small to medium-sized,
upright tree. At maturity it may reach a height of 40 to 90 feet (12-27
m) and a d.b.h. of 12 to 30 inches (30-75 cm) . Maximum age is about
200 years. Balsam fir has a dense, narrowly pyrimidal crown terminating
in a slender, spirelike top. Open-grown trees may have live branches
extending to the ground, but trees in well-stocked stands have dead,
persistent lower branches . The needles are flat, resinous, and 0.4
to 1.2 inches (1-3 cm) long . Erect cones occur on the upper side of
1-year-old branches in the upper crown. The bark is gray and smooth and
contains numerous raised resin blisters. On older trees the bark
becomes brown and scaly but is less than 0.5 inch (1.2 cm) thick .
Balsam fir has a shallow root system that is mostly confined to duff and
upper mineral soil layers. Roots rarely penetrate more than 30 inches
(75 cm) below the ground surface, except in sandy soils .
Habitat and Ecology
Balsam fir grows on a wide variety of upland and lowland sites. It
occurs on mountain slopes and glaciated uplands as well as on alluvial
flats, peatlands, and swamps. It is found in pure, mixed coniferous,
and mixed coniferous-deciduous stands.
Soils: Balsam fir grows on sites underlain by a variety of parent
materials, including gneiss, schist, anorthosite, diabase, slate,
sandstone, and limestone. It grows mostly on acid Spodosol, Inceptisol,
and Histisol soil orders . It grows on all soil textures, from
heavy clay to rocky. It tolerates a wide range of soil acidity. In the
Lake States, balsam fir is most common on cool, wet-mesic sites with
soil pH values between 5.1 and 6.0 . In northeast Wisconsin it
commonly grows on limestone outcrops .
Associated trees: Associated trees of uplands include white spruce, red
spruce, paper birch, aspen, white ash (Fraxinus americana), yellow birch
(Betula alleghaniensis), American beech (Fagus grandifolia), red maple,
sugar maple (Acer saccharum), eastern hemlock, and white pine. Lowland
associates are black spruce, white spruce, tamarack (Larix laricina),
red maple, black ash (Fraxinus nigra), and northern white-cedar .
Understory: Common shrub associates include beaked hazel (Corylus
cornuta), bog Labrador-tea (Ledum groenlandicum), mountain maple (Acer
spicatum), Canada yew (Taxus canadensis), red raspberry (Rubus idaeus),
sheep laurel (Kalmia angustifolia), and hobblebush (Viburnum
Elevation: Balsam fir grows from near sea level along the Atlantic
seaboard to timberline at 5,600 feet (1,700 m) in the Appalachian
Mountains, and to 6,200 feet (1,890 m) in the White Mountains in New
Key Plant Community Associations
Balsam fir is more commonly found in mixed than in pure stands. It does
occurs as a dominant species in pure stands in Newfoundland, Ontario,
and Quebec. Its importance as a major forest tree declines west of
Manitoba . Balsam fir is a principal tree of boreal mixed stands in
Canada, where it occurs with paper birch (Betula papyrifera), aspen
(Populus tremuloides), black spruce (Picea mariana), and white spruce
(P. glauca) .
In the Lake States, climax stands of balsam fir are relatively uncommon
[21,45]. In Maine, balsam fir forms pure stands on flats between swamps
and uplands . In the Adirondacks, balsam fir sometimes dominates
upper slopes above 3,200 feet (975 m) . In New England and the Lake
States, balsam fir is more commonly found in mixed stands, especially in
forests dominated by black spruce, red spruce (Picea rubens), white
spruce, eastern hemlock (Tsuga canadensis), northern white-cedar (Thuja
occidentalis), paper birch, aspen, and red maple (Acer rubrum)
Balsam fir is listed as a dominant part of the vegetation in the
following community type (cts) and ecosystem (eas) classifications:
Area Classification Authority
PQ: Gaspe Peninsula forest veg. cts Zoladeski 1988
ON forest eas Jones & others 1983
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K093 Great Lakes spruce - fir forest
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K107 Northern hardwoods - 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):
1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce - tamarack
15 Red pine
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
26 Sugar maple - basswood
30 Red spruce - yellow birch
31 Red spruce - sugar maple - beech
32 Red spruce
33 Red spruce - balsam fir
35 Paper birch - red spruce - balsam fir
37 Northern white cedar
39 Black ash - American elm - red maple
60 Beech - sugar maple
107 White spruce
108 Red maple
201 White spruce
202 White spruce - paper birch
204 Black spruce
251 White spruce - aspen
253 Black spruce - white spruce
Soils and Topography
Soil moisture was the most important predictor of site index in a study in Newfoundland. Soil nutrient status and topography, in that order, were of lesser importance. Glacial tills, often shallow, cover much of the area (27).
Balsam fir has been reported as growing on soils of a wide range of acidity. In the northern Lake States it is most common on cool, wet-mesic sites with pH values between 5.1 to 6.0 (19). Optimum growth occurs on soils where the pH of the upper organic layers is between 6.5 and 7.0 (1). On gravelly sands and in peat swamps, growth is comparatively slow (41).
The mean annual temperature within the range of balsam fir varies from -4° to 7° C (25° to 45° F). Mean annual precipitation records show as much as 1400 mm (55 in) to as little as 390 mm (15 in). The amount of growing season precipitation is from 150 to 620 mm (6 to 25 in) (1). There are 80 to 180 frost-free days and about 110 days for optimum growth (1).
Habitat & Distribution
The use of natural regeneration methods for balsam fir is very effective on open and disturbed sites (heavily cut areas), but an adequate seed source must exist. This species can also be readily grown in nurseries, for transplanting to abandoned fields, Christmas tree plantations, and open areas. Use conventional tree planting techniques and equipment. Three or four year old seedling stock should be utilized.
Associated Forest Cover
Pure stands of balsam fir or stands in which balsam fir is the major component of growing stock make up the forest cover type Balsam Fir (Society of American Foresters Type 5) (10). Balsam fir is also a major component in two other eastern forest cover types: Red Spruce-Balsam Fir (Type 33) and Paper Birch-Red Spruce-Balsam Fir (Type 35). It is an associated species in 22 eastern forest cover types and in 4 western forest cover types.
Common shrubs associated with balsam fir include beaked hazel (Corylus cornuta), mountain maple (Acer spicatum), Labrador-tea (Ledum groenlandicum), Canada yew (Taxus canadensis), red raspberry (Rubus idaeus var. strigosus), sheep-laurel (Kalmia angustifolia), and hobblebush (Viburnum lantanoides) (10,41).
Among the herbaceous plants commonly found under balsam fir are twinflower (Linnaea borealis), bunchberry (Cornus canadensis), starflower (Trientalis borealis), creeping snowberry (Gaultheria hispidula), sedges (Carex spp.), common woodsorrel (Oxalis montana), bluebead lily or cornlily (Clintonia borealis), painted trillium (Trillium undulatum), cinnamon fern (Osmunda cinnamomea), sweetscented bedstraw (Galium triflorum), Canada mayflower (Maianthemum canadense), and spinulose woodfern (Dryopteris spinulosa).
Certain associations of shrubs, herbs, and mosses indicate forest site quality (41). The four main indicator associations, designated as Hylocomium/ Hypnum, Cornus/Maianthemum, Oxalis/Cornus, and Viburnum/Oxalis indicate, in the order listed, increasing productivity of site and increasing proportions of shrubs and hardwood trees in natural stands. Only the Hylocomium/Hypnum sites are likely to be occupied by pure balsam fir.
Diseases and Parasites
Balsam fir has several insect enemies, the most important by far being the spruce budworm. Despite its name, the spruce budworm prefers fir over spruce; it is most likely to cause heavy damage and mortality in stands that contain mature fir, or that have a dense stocking of fir or a high proportion of fir in relation to other species. Vast budworm outbreaks in eastern North America, perhaps as many as 11 since 1704, have killed tens of millions of cubic meters (hundreds of millions of ft³) of balsam fir (6). Defoliation causes extensive root mortality. Evidence of budworm attack such as deformation, buried leaders, and decay can be seen 40 or more years later (1). Detailed articles about this important insect pest, with suggestions to alleviate damage, have been written (7,32) and a comprehensive bibliography assembled (25).
A classification system for tree vigor and budworm resistance was developed as a guide for selecting spruce and fir trees to remove or retain so as to make spruce-fir stands less vulnerable to spruce budworm attack. Silvicultural techniques designed to increase stand resistance to budworm cannot achieve their aim in the short term; several stand entries over the long term may be required, especially in stands dominated by balsam fir regeneration (46).
The balsam woolly adelgid (Adelges piceae), an introduced insect, is found in Southeastern Canada and in the Northeastern United States. Unless checked by low winter temperatures, populations build up and weaken or kill many trees. Severe stem attack can kill trees within 3 years. The insect also attacks twigs and buds, causing swellings and resulting in loss of new buds, gradual death of twigs and tops, and severe damage to regeneration. An abnormal growth of tracheids caused by insect saliva results in dark, brittle "redwood" (41).
The red heart fungus (Haematostereum sanguinolentum), causes much decay in living balsam fir. It enters almost entirely through injuries to the trunk and living branches (18). Losses from red heart rot are two or three times greater than those caused by butt rots (11,41). Six root and butt rots in balsam fir are economically important. These include the shoestring rot (Armillaria mellea), the two brown cubical rots (Tyromyces balsameus and Coniophora puteana), and the three white stringy rots (Poria subacida, Resinicium bicolor, and Scytinostroma galactinium). Another root disease of importance is Serpula himantioides. Phaeolus schweinitzii and Inonotus tomentosus also cause a small percentage of the root and butt rot in balsam fir (18). Mechanical or insect-caused wounds to the roots or basal areas of trees provide entrances for these fungi (41). Although the root and butt rots are not responsible for an excessive amount of cull in standing trees, they do weaken trees and make them more susceptible to wind damage, especially if trees are 20 cm (8 in) d.b.h. and larger. The defect caused by these rots is severe enough to be the decisive factor in setting the pathological rotation of fir at about 70 years (11,18,41).
Rot can begin in balsam fir as early as 40 years and increases as the trees get older. More than half generally are infected by the time they are 70 years old. No reliable external indicator of rot is known and even fruiting bodies are rare on living trees. Site seems to have an effect on the incidence and severity of rot; generally, the drier the site, the greater the damage from rot (41).
Specific causes of seedling diseases in nurseries have not been thoroughly reported. The foliage diseases of balsam fir are many but none are economically important to wood production. The same can be said for balsam fir's many stem or canker diseases (18).
The most conspicuous disease of balsam fir is witches' broom, caused by the rust fungus Melampsorella caryophyllacearum. Broomed shoots are upright and dwarfed and have yellow needles. Trunk and branch swellings are produced in the shoots (18).
Fire Management Considerations
Prescribed fire: Prescribed fire can be used to convert balsam fir
forests to other species. It is an important silvicultural tool in
spruce budworm-infested stands. Burning infested stands eliminates the
unaffected balsam fir understory and prepares the site for other
commercial species, particularly black spruce . In northern
Ontario, prescribed burning on sites pretreated by tramping (leveling
the dead trees with bulldozers) successfully prepared a spruce
budworm-killed balsam fir stand for planting . Tramping aided fire
spread in this summer burn, when green herbaceous plants might otherwise
have hindered it. The standing dead trees were dry before tramping.
Some large balsam fir boles were completely consumed and 55 percent of
balsam fir slash between 2.75 and 5 inches (7-13 cm) in diameter were
consumed. Prescribed fires can also be used to kill balsam fir
seedlings and saplings in pine and mixed-wood types. In these types,
low-intensity surface fires are sufficient to kill balsam fir saplings
Fire behavior: Balsam fir tree mortality is often between 70 and 100
percent after the collapse of a spruce budworm outbreak . These
altered forests are more flammable because the dead trees provide dry
aerial fuel and the newly exposed understory is drier than normal. Fire
suppression in spruce budworm-killed stands is extremely difficult .
Experimental burns in spruce budworm-killed stands have been explosive.
In balsam fir stands with 30- to 90-year-old dead trees averaging 23 to
39 feet (7-12 m) in height, spring fires (before flushing of understory
vegetation), under conditions of high but not extreme fire danger,
burned with intensities as high as 38,000 KW/m and spread rates in
excess of 148 feet/minute (45 m/min.) . Tree crown and surface fuel
consumption were nearly complete, and standing tree boles smoldered for
hours after the passage of the fire front. These hot fires transport
large amounts of peeling bark, fine twigs, and branchlets in convection
columns which start spot fires downwind .
Decay after fire: Fire-killed balsam fir deteriorates rather slowly.
Commercial salvage operations are possible for a number of years after
stand-killing fires . However, budworm-killed trees quickly succumb
to wood-rotting fungi and are largely unusable after 1 to 3 years .
Broad-scale Impacts of Plant Response to Fire
Fire creates seedbeds favorable for balsam fir germination and
establishment. If seed is available, balsam fir readily establishes on
burned sites. In northern Minnesota, balsam fir seedlings were
established within 5 years of a stand-destroying fire; seed originated
from an unburned mixed-conifer stand across a river . Balsam fir
seedlings establish after fall fires that occur when seed is ripe and
still on the tree .
Plant Response to Fire
trees are killed by fire, it relies on rare survivors found in protected
pockets within the burn or trees from adjacent unburned areas to provide
seed for postfire seedling establishment. Associates such as aspen,
paper birch, black spruce, and jack pine usually seed in aggressively
following fire and quickly dominate the site. Balsam fir is usually
rare or absent for the first 30 to 50 years after fire, but thereafter
gradually establishes under the canopy of its seral associates
Immediate Effect of Fire
Balsam fir is the least fire-resistant conifer in the northeastern
United States . Most fires kill balsam fir trees and destroy the
seeds . Trees have thin, resinous, easily ignitable bark and
shallow roots [1,21]. Seeds have no endosperm to protect them from high
temperatures. Cones are not necessarily destroyed by fire, but immature
seeds will not ripen on fire-killed trees.
If balsam fir trees are killed over extensive areas by summer fires, no
seed will be available to revegetate the burned area. This occurred
following the 1936 wildfire on Isle Royale which burned 26,000 acres
(10,500 ha). Most of the balsam fir trees were killed, and for 30 years
after the fire, balsam fir was largely absent from the burned area .
Tree without adventitious-bud root crown
Secondary colonizer - off-site seed
only if surviving seed trees are present. Balsam fir is therefore a
rare postfire pioneer .
More info for the terms: climax, mesic
Balsam fir is a late successional or climax species. Following fire, it
is replaced by pioneering hardwoods and conifers, such as aspen, paper
birch, balsam poplar (Populus balsamifera), jack pine, and black spruce.
Except for scattered survivors, it is mostly absent for the first few
postfire decades. In Ontario, balsam fir seedlings often first appear
under aspen-birch-spruce types 30 to 50 years after fire [5,36]. Balsam
fir seedlings are shade tolerant and less exacting in seedbed
requirements than many associates. It readily establishes under a
canopy of hardwoods and conifers. In the Lake States, an understory of
balsam fir seedlings is almost ubiquitous in several upland and lowland
forests . In boreal forests, it is usually a common understory
component beneath pines, aspen, and paper birch [7,15,28]. In the
continued absence of fire, balsam fir may assume dominance as the canopy
of the pioneering trees begins to break up.
In the Lake States, balsam fir can become climax on poorly drained clay
soils. It often succeeds aspen, paper birch, and sometimes black spruce
. On mesic sites, it is often replaced by shade-tolerant hardwoods
such as sugar maple .
Seed production and dispersal: Balsam fir is a prolific seed producer.
Seed production begins when plants are about 20 years old or 15 feet
tall , and regular seed production occurs after trees are about 30
years old. Some seed is produced every year, with heavy seed crops
occurring at 2- to 4-year intervals . Most seeds are shed in
autumn, but small amounts fall throughout the winter and into spring
. The winged seeds are primarily dispersed by wind. Most fall
within 80 to 200 feet (25-60 m) of the tree, but some travel up to 525
feet from the tree (160 m) . Some seed is dispersed by small
Only about 50 percent of balsam fir seeds are sound . Germinative
capacity is relatively low, ranging from about 20 to 50 percent .
Seeds remain viable for less than 1 year under natural conditions .
Germination and seedling establishment: Most seeds germinate between
late May and early July . If moisture is sufficient, seedlings will
establish on almost any substrate, but establishment is generally best
on mineral soil. Other good seedbeds include rotting wood embedded in
humus because it can remain moist even during prolonged drought, and
rotting logs and stumps because they have a tendency to shed hardwood
leaf litter which can smother seedlings . Hardwood leaf litter is a
poor seedbed; seedlings on deep layers of hardwood litter usually die
within a few weeks of germination . However, balsam fir establishes
more readily on shallow litter (less than 3 inches [7.5 cm]) than other
conifers because seedlings quickly develop a deep root system .
Seedlings are very shade tolerant. Once established they can withstand
many years of suppression.
Vegetative reproduction: Layering occurs in swamps and mossy areas, and
under white and jack pine (Pinus strobus, P. banksiana) overstories .
In the White Mountains of New Hampshire, prostrate balsam fir above
5,500 feet (1,700 m) in elevation reproduce almost entirely by layering
Growth Form (according to Raunkiær Life-form classification)
Reaction to Competition
In New England, balsam fir is considered a subclimax type, except that it may be a climax species in the zone below timberline. It tends to become climax in Quebec and in the Lake States (41).
Root penetration on deep or shallow soils extends to 60 to 75 cm (24 to 30 in) and has been reported to a depth of 137 cm (54 in) in sandy soils in northern Ontario. Lateral roots of balsam fir are usually strongly developed and extend horizontally in all directions to 1.5 m (5 ft) or more (1).
Root breakage and other root damage caused by swaying trees may not be as severe as is commonly thought. Most investigators agree, however, that some root breakage probably occurs because of frostheaving and swaying. During epidemics of spruce budworm (Choristoneura fumiferana), rootlet mortality can reach 75 percent after 3 consecutive years of defoliation (1).
Balsam fir root grafts are probably common and have been reported frequently. Abrasion of the bark of roots of swaying trees on lowland soils and interroot compatibility and growth pressure on upland soils apparently account for the majority of root grafts. Infection may spread through grafted roots to damage other balsam fir trees (1).
Life History and Behavior
Phenological events proceed as follows :
Event Southern part of range Northern part of range
flowering begins early May early June
seeds ripen late August-early Sept. October
seedfall begins early September October
Balsam fir apparently grafts easily (41). In a study in New York, greenhouse grafts were 85 percent successful and field grafts were 80 percent successful. One attempt to air-layer balsam fir was unsuccessful (1). Balsam fir Christmas trees are stump cultured from lateral branches or adventitious shoots.
A study in Michigan (41) showed that germination was highest for a 41-year-old tree (68 percent), varied for trees 30 years old (8 to 57 percent), and was lowest for trees 155 years old (10 percent). Testing of 32 commercial seed lots showed average germination of about 26 percent with a range of 4 to 62 percent (42). Once the seed reaches the ground, its viability diminishes quickly and is gone within 1 year (13). It has been suggested, however, that in cold swamps viability of some seeds is retained for 2 to 3 years (1).
Most germination occurs from late May to early July. Survival the first winter is questionable if germination occurs after mid-July (1). If enough moisture is available, almost any seedbed type is satisfactory, but mineral soil-neither too sandy nor too heavy-with some shade is best. Litter and humus are poor seedbeds, especially if moisture is inadequate or -light is excessive. Competition, often severe, makes heavy sod the poorest seedbed (11).
A thick layer of duff exceeding about 8 cm (3 in) is less favorable for balsam fir but even worse for the slower growing associated spruces. Balsam fir seedlings may have a heavy central root, much like a taproot, that extends to the bottom of the humus layer and then splits into several laterals. In general, balsam fir roots grow more rapidly and penetrate deeper than red spruce roots. Where seasonal root elongation of young balsam fir growing in humus averaged 10.6 cm (4.2 in), red spruce was 7.6 cm (3.0 in), and white spruce 9.0 cm (3.5 in), or 39 percent and 18 percent less, respectively (1).
Because the surface of thick duff usually dries out, there may be some delayed germination as late as August. Few seedlings become established, however. The closer seeds lie to mineral soil, the greater the initial establishment of seedlings.
Seedlings starting in the open may sustain heavy mortality when surface temperatures exceed 46° to 54° C (115° to 130° F) or when there is drought or frost heaving. Seedlings may also be smothered or crushed by litter, ice, snow, and hardwood leaves. Losses after the first year usually are minor. As seedlings develop, light at intensities of at least 50 percent of full sunlight are necessary for optimum growth (11,41). Damage caused by late spring frost to new foliage of young seedlings is seldom severe.
Balsam fir seedlings about 15 cm (6 in) tall can be considered to be established (11), especially if secondary branching has occurred. Early growth is then determined largely by the amount and character of dominant competition. Bracken, raspberry, and hardwood sprouts-especially the maples-are the chief competitors on heavily cutover lands in the Northeast. These species may increase dramatically when the original basal area is reduced by 50 percent or more and may dominate the site for 10 to 25 years (2). Unless there has been some soil disturbance, there will be little regeneration of balsam fir and spruce immediately following logging (45). Both balsam fir and the spruces can survive many years of suppression and still respond to release (11,41). The space required for the continual development and establishment of new seedlings probably exceeds that created by the removal of individual trees. To ensure successful regeneration relatively small groups of trees should be removed initially (12).
Seed Production and Dissemination
The period of balsam fir seedfall is long and dissemination distances vary. Seedfall begins late in August, peaks in September and October, and continues into November. Some seeds fall throughout the winter and into early spring. Most of the seeds are spread by wind-some to great distances over frozen snow-and some are spread by rodents. Although seeds may disseminate from 100 m (330 ft) to more than 160 m (525 ft), effective distances are 25 m to 60 m (80 to 200 ft) (1,11,28). Many seeds falling with the cone scales land close to the base of the tree.
Balsam fir seeds have dormant embryos and should be stratified in moist sand at about 50 C (410 F) for at least 30 days before planting. Germination is epigeal (42).
Flowering and Fruiting
Balsam fir is monoecious. In spring, 1 year before pollination, male (staminate) and female (ovulate or pistillate) strobili differentiate from flower buds. The strobili are microscopically recognizable at this time. Male strobili usually are distinguishable before the female strobili because they initially develop more rapidly. Flower buds usually open in late May or early June before vegetative buds (41) but have been reported as flowering as early as late April (42).
Male strobili, yellowish-red and tinged with purple, develop in the axils of leaves along the undersides of the 1-year-old twigs, usually in dense clusters. Their position in the crown is mostly within 5 m (15 ft) of the top and is almost always below the female strobili. Female strobili are purplish and are found singly or in small groups, confined to the top 1.5 m (5 ft) of the crown. They are located on the upper side of the twig and, like the male strobili, develop on the previous year's twig. Flower production is best on the outer end of branches (41,42). At maturity, male flowers are about 3 mm (0.1 in) long; female flowers are about 25 mm (1.0 in) long (1).
Pollen grains are yellow; when developed, their average diameter is 90 µ (0.00354 in). In one series of observations in Ontario, fertilization occurred on June 25 (1). The mature fruit is an erect cone 5 to 10 cm (2 to 4 in) long with short, round, irregularly notched scales and pointed tips. There are thin, closely overlapping fan-shaped scales near the center of the cone. The cone matures and ripens during the first fall in late August and early September. The scales and shorter bracts drop away with the seeds, leaving the central axis, which can persist for many years.
Growth and Yield
Diameter growth was related to vigor and crown length-to-height ratio in a study in Maine. Balsam fir with high vigor and a ratio of at least 0.7- the proportion of live-crown length to total tree height averaged 6.1 cm (2.4 in) of growth in d.b.h. in 10 years. Less vigorous trees with smaller crown-length ratios ranged downward to an average of 1.0 cm (0.4 in) of growth in 10 years. Vigorous trees with room to grow attain a d.b.h. of at least 25 cm (10 in) in about 50 years (41). In uneven-aged stands of several density classes in Maine, balsam fir grew faster in diameter than spruce and hemlock (35).
Data obtained from stem analysis of balsam fir growing on sites of varying quality in northern Maine has shown height growth curves to be polymorphic (fig. 1). Height growth varies with site quality. From these curves the average site index of a stand can be estimated (16). Monomorphic or harmonized site index curves for balsam fir are also available (17).
Figure 1-Polymorphic site index curves (base age 50 years
at breast height) for balsam fir in northern Maine, as derived
from stem data (16).
Balsam fir is a strong contender for space in stands in which it grows. A 20-year record of stands containing balsam fir in the Penobscot Experimental Forest in Maine showed that the periodic annual volume ingrowth of the species, as a proportion of total volume ingrowth, greatly exceeded its representation in the original stands (12). Because of its many natural enemies, however, volume mortality of balsam fir also greatly exceeds its original representation in these stands.
Balsam fir accounted for 35 percent of the average annual net growth in predominantly softwood stands and 32 percent in mixed stands that were extensively managed. These stands were growing at annual rates of 3.5 m³/ha (49.3 ft³/acre) and 2.9 m³/ha (41.1 ft³/acre), respectively (31).
Yields in total cubic-foot volume, including stump and top, of all trees larger than 1.5 cm (0.6 in), in d.b.h. are given in table 1. These yields are based on sample plots in even-aged spruce-fir stands, mostly on old fields. They tend to exaggerate the yields that might be expected from the irregular stands that develop after harvesting (41).
Table 1- Total tree volume (exclusive of roots) of balsam fir greater than 1.5 cm (0.6 in) in d.b.h. by age and site index (41). Site index¹ 12.2 m
or 40 ft 15.2 m
or 50 ft 18.3 m
or 60 ft 21.3 m
or 70 ft Age yr m³/ha 20 6 8 9 12 30 50 67 85 102 40 136 182 229 276 50 204 274 344 414 60 245 329 413 497 70 267 360 452 543 80 286 384 481 579 90 300 403 506 609 yr ft³/acre 20 80 110 135 165 30 720 960 1,210 1,455 40 1,940 2,600 3,270 3,940 50 2,190 3,920 4,920 5,910 60 3,500 4,700 5,900 7,100 70 3,820 5,140 6,450 7,760 80 4,080 5,480 6,870 8,270 90 4,290 5,760 7,230 8,700 ¹Base age 50 years when age is measured at d.b.h.- total tree age is estimated to be 65 years at that time. Simulating the management and growth of forest stands containing balsam fir is possible because of advances in computer technology. A matrix model, FIBER (36), has been developed for stands in the Northeast. Even-aged and multi-aged stands, containing balsam fir, spruce, northern hardwoods, and other associated species, can be programmed to simulate a range of silvicultural treatments.
In a ranking with both hardwoods and softwoods from around the world, balsam fir is highest with a total above-ground ovendry biomass at age 50 of 184 t/ha (82 tons/acre). Annual increment or annual net primary production averages 10.3 t/ha (4.6 tons/acre) (20). In New Brunswick (3), dry-matter production of balsam fir in pure stands increased dramatically with increases in stand densities of from 1,730 stems per hectare (700/acre) to 12,350/ha (5,000/acre). At an average age from release of 43 years, total above-ground biomass was 96 t/ha (43 tons/acre) for the least dense stand and 143 t/ha (64 tons/acre) for the most dense stand.
Molecular Biology and Genetics
Balsam fir seedlings grown from seed collected along an elevational gradient in New Hampshire showed a clinal pattern of carbon dioxide uptake with respect to the elevational gradient. This suggests an adaption to temperature through natural selection (14). Another study failed to show that geographical variation in food quality of balsam fir needles is important to the spruce budworm diet but did suggest variation in food quality between locations (33).
In the southern Appalachians the monoterpenes- alpha-pinene and beta-phellandrene- appear to be the best taxonomic characteristics for separating balsam fir from Fraser fir, with alpha-terpene increasing southward and beta-terpene increasing northward. Because no regional variation pattern was evident for wood specific gravity or tracheid length, it has been suggested that only one species of balsam fir with three varieties be recognized in the Eastern United States: Abies balsamea var. balsamea, Abies balsamea var. phanerolepis, and Abies balsamea var. fraseri (29,39).
Balsam fir provenances from eastern portions of the range exhibited more vigor than those from western portions (24). This trait continued through 11 (22) and 13 years of total tree age (9). Southern sources tended to flush later, indicating selection for minimizing damage from the balsam gall midge (Dasineura balsamicola) and for resistance to late spring frost.
Specific gravity and tracheid length generally vary along an east-west gradient, with eastern sources of lower specific gravity and longer tracheids (9). Generally, trees from slow-growing sources have higher specific gravities and shorter tracheids than trees from fast-growing sources.
Races and Hybrids No distinct races of balsam fir have been identified. Botanical varieties of balsam fir have been described, Abies balsamea var. phanerolepis being most important. This variety, the bracted balsam fir, is distinguished by its cone scales, which are shorter than the bracts. The variety phanerolepis is found infrequently from Labrador and Newfoundland to Maine and Ontario, and in the high mountains of New Hampshire, Vermont, and New York. It is found locally in northern Virginia and West Virginia (21,41,42), and commonly in several locations in Nova Scotia.
Until the late 1930's, natural or artificial hybrids of balsam fir had not been reported in North America. There were earlier reports, however, of hybrids between balsam fir and Siberian fir (Abies sibirica) in Europe (1).
Balsam fir is closely related to Fraser fir (A. fraseri). A taxon of doubtful status, A. intermedia, representing a possible cross between the two species, has been reported. This cross has also been reported as A. balsamea var. phanerolepis (1). Subalpine fir (A. lasiocarpa) also may hybridize with balsam fir where they adjoin in Alberta (42). Workers in Canada apparently have been successful in some instances in hybridizing balsam fir with several species of Abies, among them European silver fir (A. alba), alpine fir, and Fraser fir (1). Similar attempts in the United States have been only partially successful.
European horticulturists have propagated many forms of balsam fir for ornamental purposes. Plant form, needle color, and branch length and angle are characteristics usually manipulated. Nineteen such cultivars have been listed (1).
Statistics of barcoding coverage: Abies balsamea
Public Records: 0
Specimens with Barcodes: 4
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Abies balsamea (L.) Mill. var. phanerolepis Fernald is assessed as Data Deficient. The subpopulations of this variety are undoubtedly relatively small and scattered (fragmented) but there is insufficient information about their number, extent of occurrence (EOO) and area of occupancy (AOO) for a credible assessment to be made. Another problem is identity and several reports and specimen databases of herbaria list occurrences in Canada (e.g. Nova Scotia at the Harvard Herbaria) which are likely to be just forms of A. balsamea var. balsamea with (slightly) exserted bracts.
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).
Silviculture: Balsam fir is managed under both even- and uneven-aged
silvicultural systems [22,23,30]. Balsam fir types are usually
converted to other forest types because of their susceptibility to
spruce budworm outbreaks and because of the relatively low value of the
Wildlife damage: White-tailed deer, snowshoe hares, and especially
moose browse balsam fir reproduction on cutovers. This often retards
growth but is seldom fatal . In Newfoundland, 4-foot-tall (1.2 m)
balsam fir survived up to 12 years of heavy moose browsing .
Release: Several herbicides are used to release balsam fir from
competing hardwoods. Balsam fir is resistant to 2,4-D, 2,4,5-T,
glyphosate, and hexazinone [30,40].
Insects: The spruce budworm is the most serious damaging agent of
balsam fir. Historically, cyclical spruce budworm epidemics have killed
trees over vast areas . The most susceptible stands are those
with the following characteristics :
(1) High basal area or percentage of stand in balsam fir and/or white
(2) Mature stands (50 years or older), especially if
(3) Open stands with tops of balsam fir and/or white spruce
protruding above the canopy;
(4) Stands on poorly drained soils that are extremely wet or dry; and
(5) Stands downwind of a budworm outbreak area.
Once an outbreak begins, trees usually die after 3 to 5 years of
continuous defoliation. Johnston  has outlined management
principles for spruce-budworm-infested balsam fir.
Other serious insect pests include the hemlock looper and blackheaded
budworm, defoliators primarily associated with mature and overmature
stands . The introduced balsam wooly adelgid, which occurs in
southeastern Canada and the northeastern United States, attacks stems,
twigs, and buds and can kill trees within 3 years .
Rots: Several heart, butt, and root rots cause much decay in living
trees. Heart rots often infect more than 50 percent of 70-year-old
Cultivars, improved and selected materials (and area of origin)
Although most available seedlings of balsam fir are of unknown parentage, some are produced from local selections.
This section is under development. Please consult the Related Web Sites links on the PLANTS Plant Profile.
Relevance to Humans and Ecosystems
Uses: Spice/herb/condiment, Beverage (non-alcoholic), Other food, Folk medicine
Comments: Used for colds and pulmonary troubles. Tea of inner bark used for chest pains. Seasoner for other medicines. Fresh inner bark poultice. Young leaves make a good tea. Gum from needles, branches, and cones chewed in B.C.
Other uses and values
Balsam fir is a popular Christmas tree in the East and grown on
plantations for this purpose. The branches are used to make Christmas
wreaths. The fragrant needles are used as a stuffing in souvenir
pillows sold in New England .
Balsam fir is occasionally used in landscaping. It can be used in
screenings, mass plantings, and windbreaks but requires abundant soil
moisture for these purposes .
Bark blisters contain oleoresin, which is used in the optics industry as
a medium for mounting microscope specimens and as a cement for various
parts of optical systems .
Balsam fir provides important winter cover for white-tailed deer and
moose. Balsam fir stands attract ungulates because snow is not as deep
as in adjacent hardwood stands . Lowland balsam fir stands are used
extensively by white-tailed deer as winter yarding areas , and by
moose with calves during severe winters . During summer, deer,
bear, and moose often rest under the shade of balsam fir trees .
Young balsam firs provide cover for small mammals and birds. Martens,
hares, songbirds, and even deer hide from predators in balsam fir
thickets . Grouse and songbirds seek shelter during winter within
the evergreen foliage . In Maine, fishers often nest in witches
brooms in balsam fir trees .
Wood Products Value
Balsam fir wood is used primarily for pulpwood and lumber for light
frame construction. It is also used extensively for cabin logs. The
wood is lightweight, relatively soft, low in shock resistance, and has
good splitting resistance. Balsam fir is not well suited for use as
posts and poles because it decays rapidly. Minor wood products include
paneling, crates, and other products not requiring high structural
Value for rehabilitation of disturbed sites
It is probably best suited for long-term revegetation. Nursery-grown
stock is available for outplanting. Methods for collecting, processing,
testing, storing, and sowing balsam fir seed, as well as nursery
practices for seedling production, have been outlined in the literature
Importance to Livestock and Wildlife
utilized more when snow is deep and moose populations are high .
Moose may browse balsam fir in winter to save energy because the twigs
weigh 8 to 13 times more than deciduous twigs of similar length and
therefore it requires less time and effort to consume equivalent amounts
. Balsam fir is unimportant in the diets of caribou and
white-tailed deer. Spruce and ruffed grouse feed on balsam fir needles,
tips, and buds, which often make up 5 to 10 percent of the fall and
winter diet. Red squirrels feed on balsam fir male flower buds, and
less frequently on leader and lateral buds in late winter and spring
when other foods are scarce . Stands attacked by the spruce budworm
attract numerous insect-eating birds, especially warblers and
are more nutritious than plants with yellow or light green foliage.
Chemical analysis of balsam fir browse during the growing season varied
according to color as follows :
(percent composition on dry matter basis)
foliage color protein fat fiber ash N-free Mg K
very yellow 4.65 7.54 25.2 2.1 60.60 0.12 0.32
yellow 5.49 8.29 22.01 2.49 61.72 0.18 0.15
light green 6.33 7.71 22.83 2.44 60.69 0.13 0.27
green 6.89 8.08 21.36 3.24 60.43 0.13 0.42
dark green 8.59 7.88 20.67 3.54 59.41 0.09 0.44
dark blue-green 13.54 5.55 26.24 3.68 50.99 0.13 1.01
On logged-over land in Newfoundland, twigs from balsam fir saplings in
thinned stands contained 33 percent more protein and 17 percent more
crude fat than those from unthinned stands .
Palatability varies between individual plants. Green-foliaged
individuals are often browsed heavily, while chlorotic plants are
avoided . This is attributed to the higher nutrient content of
healthy plants with dark green foliage.
The palatability of balsam fir to white-tailed deer and caribou is low
. White-tailed deer may eat small amounts of balsam fir due to its
abundance, but it is not a preferred food .
In laboratory experiments, mice and voles preferred the seeds of pines
(Pinus spp.), spruces (Picea spp.), and eastern hemlock over balsam fir
Balsam fir is pulped by all of the pulping processes. Sulfate and semichemical processes are used most extensively. A fiber length of 3 to 4 mm A 12 to 0.16 in) is good, as is fiber quality. Because balsam fir is less dense than other major pulpwood species, its yield is lower (37).
The wood of balsam fir is light in weight, relatively soft, low in shock resistance, and has good splitting resistance. Recent testing of several mechanical properties of balsam fir and of red, white, and black spruce indicates strength values for balsam fir generally exceeding those of white spruce. In some tests, strength values were equivalent to or only slightly below the values of red and black spruce (5,34). Nail-holding capacity is low. Balsam fir is very low in resistance to decay (43). The major use of balsam fir lumber is for light-frame construction. Minor uses include paneling, crates, and other products not requiring high structural strength.
Balsam fir provides food or cover for some animals and both food and cover for others. Moose rely on balsam fir in winter when it is a major source of food. The use of balsam fir by deer for cover and shelter is well documented. During severe winter weather, especially in northern areas of the white-tailed deer range, lowland balsam fir stands and spruce-balsam fir swamps are used extensively as winter yarding areas. The fact that these sites usually contain, at best, only small amounts of preferred food suggests their attractiveness as shelter.
Other mammals use balsam fir to varying degrees. The snowshoe hare uses it for cover, and there is some seed and phloem feeding by various species of mice and voles. Red squirrels occasionally feed on balsam fir seed, bark, and wood. They prefer flower buds to vegetative buds. There is some use of wood by beaver for dam building, but little is used as food. Black bear strip bark and lick the exposed surfaces between bark and wood (1).
Balsam fir provides a minor part of the diet for both the spruce grouse and the ruffed grouse. Buds, tips, and needles are consumed, and more feeding occurs in winter than in summer. Thickets of balsam fir provide shelter for both birds (1). The response of bird populations to several forestry practices in stands containing balsam fir has been recorded (8,40). Species composition, the vertical and horizontal structure of the stand, and the extent of spruce budworm infestation influence the composition and density of bird populations.
Balsam fir is not widely planted as an ornamental nor does it offer much potential in areas other than northern New England, Canada, and perhaps the Lake States. Plantings as screens or as windbreaks are successful only when the moisture requirement of the species is met (1). On certain lands and especially on public lands, the unique presence of spruce-fir stands suggests management for esthetic values. In the southern Appalachian mountains, coniferous forests containing balsam fir are managed for watershed protection (44).
Oleoresin, a substance confined to the bark blisters of balsam fir, is used as a medium for mounting microscopic specimens and as a cement for various parts of optical systems. It is also used in the manufacture of medicinal compounds and spirit varnishes (4).
Balsam fir wood is not prized for fuelwood, but industries that use balsam fir for pulp and lumber products are using increasingly larger quantities of wood waste for the production of energy. The heating value of ovendry fir bark is 21 166 600 joules/kg (9,100 Btu/lb) (26).
The fir tree has been a favorite Christmas tree for more than 400 years. It remains among the top three species. In 1980, balsam fir ranked second behind Scotch pine (Pinus sylvestris), commanding 13.9 percent of the market (38). Sheared plantation-grown trees are usually preferred over wildings by retailers and consumers. Wreath-making is another holiday business that rivals that of Christmas tree sales in some areas. Prolonged needle retention after harvest, color, and pleasant fragrance are characteristics of balsam fir that make it attractive for these uses. Fragrance alone accounts for use of the needles as stuffing for souvenir pillows commonly sold in New England gift shops.
Balsam fir is used primarily for Christmas trees and pulpwood, although some lumber is produced from it in New England and the Lake States. The wood is light in weight, low in bending and compressive strength, moderately limber, soft, and low in resistance to shock.
Abies balsamea or balsam fir is a North American fir, native to most of eastern and central Canada (Newfoundland west to central British Columbia) and the northeastern United States (Minnesota east to Maine, and south in the Appalachian Mountains to West Virginia).
Balsam fir is a small to medium-size evergreen tree typically 14–20 metres (46–66 ft) tall, rarely to 27 metres (89 ft) tall, with a narrow conic crown. The bark on young trees is smooth, grey, and with resin blisters (which tend to spray when ruptured), becoming rough and fissured or scaly on old trees. The leaves are flat needle-like, 15 to 30 millimetres (½–1 in) long, dark green above often with a small patch of stomata near the tip, and two white stomatal bands below, and a slightly notched tip. They are arranged spirally on the shoot, but with the leaf bases twisted to appear in two more-or-less horizontal rows. The cones are erect, 40 to 80 millimetres (1½–3 in) long, dark purple, ripening brown and disintegrating to release the winged seeds in September.
There are two varieties:
- Abies balsamea var. balsamea (balsam fir) – bracts subtending seed scales short, not visible on the closed cones. Most of the species' range.
- Abies balsamea var. phanerolepis (bracted balsam fir or Canaan fir) – bracts subtending seed scales longer, visible on the closed cone. The southeast of the species' range, from southernmost Quebec to West Virginia. The name 'Canaan Fir' derives from one of its native localities, the Canaan Valley in West Virginia. Some botanists regard this variety as a natural hybrid between balsam fir and Fraser fir (Abies fraseri), which occurs further south in the Appalachian mountains.
This tree provides food for moose, American red squirrels, crossbills and chickadees, as well as shelter for moose, snowshoe hares, white-tailed deer, ruffed grouse and other small mammals and songbirds. The needles are eaten by some lepidopteran caterpillars, for example the Io moth (Automeris io).
Both varieties of the species are very popular as Christmas trees, particularly in the northeastern United States. The resin is used to produce Canada balsam, and was traditionally used as a cold remedy and as a glue for glasses, optical instrument components, and for preparing permanent mounts of microscope specimens. The wood is milled for framing lumber (part of SPF lumber), siding and pulped for paper manufacture. Balsam fir oil is an EPA approved nontoxic rodent repellent. The balsam fir is also used as an air freshener and as incense.
Prior to the availability of foam rubber and air mattresses; balsam fir boughs were a preferred mattress in places where trees greatly outnumbered campers. Many fir limbs are vertically bowed from alternating periods of downward deformation from snow loading and new growth reaching upward for sunlight. Layers of inverted freshly cut limbs from small trees created a pleasantly fragrant mattress lifting bedding off the wet ground; and the bowed green limbs were springs beneath the soft needles. Upper layers of limbs were placed with the cut ends of the limbs touching the earth to avoid uncomfortably sharp spots and sap.
- Farjon, A. (2013). "Abies balsamea". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved May 2, 2014.
- "PLANTS Profile for Abies balsamea (balsam fir)". USDA PLANTS. Retrieved 2007-07-17.
- [dead link]
- Thoreau, Henry David The Maine Woods Apollo edition (1966) Thomas Y. Crowell Company
- "RHS Plant Selector Abies balsamea Hudsonia Group AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2012-08-30.
In Alberta, populations intermediate between western Abies balsamea and A . bifolia (E.H. Moss 1953; R.S. Hunt and E.von Rudloff 1974, 1979) may be classified as A . balsamea ´ bifolia . In West Virginia and Virginia, populations of balsam fir tend to be more similar to A . fraseri than are more northern populations (B.F. Jacobs et al. 1984).
Balsam fir ( Abies balsamea ) is the provincial tree of New Brunswick.
Names and Taxonomy
Comments: Abies balsamea is a widespread species of Canada and the northeastern U.S., occurring southward in the Appalachians to West Virginia and adjacent northwestern Virginia. The similar Abies fraseri, of the high mountains of southern Virginia, North Carolina, and Tennessee, differs primarily in its longer, projecting cone-bracts. Plants intermediate between these two species have been called Abies balsamea var. phanerolepis or Abies x phanerolepis; opinions differ on whether they are relicts of the original divergence or recent interspecific hybrids; such plants occur in West Virginia and are reported irregularly northward as far as eastern Canada. LEM 10Aug00.
The currently accepted scientific name of balsam fir is Abies balsamea
(L.) Mill . The genus Abies consists of about 40 species of
evergreen trees found in the Northern Hemisphere. Nine Abies species,
including balsam fir, are native to the United States.
Balsam fir is widely distributed and exhibits geographic variation. Two
varieties based on morphological differences are recognized :
var. phanerolepis Fern.
Balsam fir is closely related to Fraser fir (A. fraseri). These species
are probably relicts of an ancestral taxon which exhibited north-south
clinal variation . Trees in Virginia and West Virginia are possibly
hybrids between these two species . Some authorities recognize
Fraser fir as a variety of balsam fir: A. b. var. fraseri .
Balsam fir hybridizes with subalpine fir (A. lasiocarpa) where their
ranges overlap in the Canadian Rockies .
bracted balsam fir