Subalpine Fir

More info for the term: prescribed fire

For further information on subalpine fir response to fire, see Fire Case Studies. Hamilton's Research Project Summary and Research Papers
(Hamilton 2006a, Hamilton 2006b)provide information on prescribed fire and
postfire response of plant community species, including subalpine fir,
that was not available when this species review was originally written.

subalpine fir
alpine fir
western balsam fir
balsam
white balsam
balsam fir
white fir
Rocky Mountain fir
pino real blanco
cork-bark fir
corkbark fir
Arizona fir

More info for the term: cover

Big game:  Subalpine fir habitat types provide excellent hiding cover
for deer, elk, mountain goats, moose, and bear [10,113].  Certain low
elevation subalpine fir forests may be used by elk during calving, and
high elevation subalpine fir forests by bighorn sheep during lambing and
lamb rearing [113].  Dense stands provide cool summertime shade for big
game animals [71].  In Yellowstone National Park, grizzly bear daybeds
are often found in subalpine fir stands [19].

Small mammals and birds:  Small subalpine firs provide good year-round
hiding cover.  Dense thickets of small trees are often nearly
impenetrable and provide hiding places for small mammals such as
snowshoe hares and porcupines [13,71].  Blue grouse often overwinter in
subalpine trees and rely almost exclusively on them for escape cover
[103].  Subalpine fir snags are used by numerous cavity-nesting birds,
but are generally less preferred than those of associated conifers
[105].

The degree to which subalpine fir provides environmental protection
during one or more seasons for wildlife species is as follows [30]:

                       CO    MT    WY    UT
Pronghorn             ----  ----  poor  poor
Elk                   good  fair  good  good
Mule deer             good  fair  good  good
White-tailed deer     ----  ----  poor  ----
Small mammals         good  good  good  good
Small nongame birds   good  fair  good  good
Upland game birds     good  good  good  fair
Waterfowl             ----  ----  poor  poor

More info for the terms: monoecious, tree

Subalpine fir is a native, coniferous, evergreen tree.  It is the
smallest of the eight species of fir native to the western United
States.  Five growth forms, each apparently an adaptation to a
particular environment, are described below [9,54]:

1.  The typical form is found throughout much of the subalpine zone.
These trees have an extremely narrow and dense crown with short
branches.  Trees growing in openings retain their lower branches, which
often droop and extend down to the ground.  Trees growing in the
overstory may be clear of lower branches for 20 to 30 percent of the
tree's height.

2.  A somewhat broad-crowned, bullet-shaped tree is more typical of
older specimens and drier climates. 

3.  A mature tree with a layered apron is occasionally found in some
areas.

4.  A flag form tree often occurs at timberline.  These individuals are
characterized by an upright trunk that extends above a krummholzlike
mat.  Branches on the trunk generally grow only along the leeward side
of the trunk, giving the plant a flaglike appearance.

5.  The krummholz form is typical of alpine areas above timberline.  In
these areas, because of cold temperatures and severe winds, subalpine
fir grows in dwarfed, shrubby mats along the ground, and is often much
broader than it is tall.

The typical form often grows to heights of 60 to 100 feet (18-30 m), and
trunk diameters reach 18 to 24 inches (46-61 cm) [39].  Trees up to 130
feet (40 m) tall and 30 inches (76 cm) in diameter have been found but
are rare [39].  Subalpine fir grows very slowly; 150- to 200-year-old
trees are usually only 10 to 20 inches (25-50 cm) in diameter [39].
Trees seldom live more than 250 years because they are very susceptible
to heart rots [9].

Needles are blunt tipped, flattened, and 1 to 1.2 inches (2.5-3 cm) long
[25,57].  Bark on young trees is thin, gray, and smooth, with numerous
resin vesicles; on older trees it is shallowly fissured and scaly [9].
Corkbark fir is generally recognized by its creamy-white, thick, corky
bark [25].  The root system generally is shallow but under favorable
conditions may develop relatively deep laterals [9].

Subalpine fir is monoecious.  Single or small bunches of erect female
cones occur in the upper part of the crown on the upper side of young
branches.  Dense clusters of the smaller male cones occur lower on the
crown on the underside of 1-year-old twigs.  Subalpine fir seeds are
0.23 to 0.28 inch (6-7 mm) long and have broad wings about 0.4 inch (1
cm) long [25,121].  Corkbark fir seeds are about 70 percent larger than
subalpine fir seeds [39].

Subalpine fir is the mostly widely distributed fir in North America,
spanning more than 32 degrees of latitude [11].  It occurs chiefly in
mountainous areas from the Yukon interior near treeline and along the
coast of southeastern Alaska south through western Alberta and British
Columbia to southern Colorado and scattered mountain ranges of Arizona
and New Mexico [54,75].  In the western portion of its range, subalpine
fir does not occur along the western slope of the Coast Range in
southern British Columbia or along the Coast Ranges of Washington and
Oregon but does occur on Vancouver Island and in the Olympic Mountains
of Washington [11].  It occurs on both slopes of the Cascade Mountains
as far south as southern Oregon [11].  The two varieties are distributed
as follows [11,75]:

A. l. var. lasiocarpa (typical variety) - almost the same as the species,
but not in central and southeastern Arizona. 

A. l. var. arizonica - from central Colorado to southwestern New Mexico, and
in southeastern and central Arizona. 

Subalpine fir and corkbark fir occur together in scattered mountain
ranges in southwestern Colorado, northern, western, and southwestern New
Mexico, and in the high mountains of Arizona [11].


 
Distributions of corkbark fir (A) and the typical variety (B). Maps courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [117] [2018, March 22].

More info for the terms: crown fire, fire regime, forest, frequency, fuel, lichens, tree

Plant adaptations to fire:  Subalpine fir is very fire sensitive and
generally suffers high mortality even from low intensity fires.  It
relies on wind-dispersed seeds which readily germinate on fire-prepared
seedbeds to colonize burned areas.  The occasional mature tree which
survives fire, those escaping fire in small, unburned pockets, and trees
adjacent to burned areas provide seeds to colonize burned sites.  In
subalpine habitats, scattered subalpine fir trees often escape fire
because of discontinuous fuels, broken and rocky terrain, and the moist
and cool environment [78,87,91].

Fire regime:  Subalpine fir habitat types vary from cold and wet at
higher elevations to warm and moist or cool and dry at lower elevations.
This environmental gradient influences the mean fire return interval
(MFRI).  Relatively dry lower elevation subalpine fir habitat types have
more frequent and less intense fires than moist middle and upper
elevation subalpine fir habitat types [12,91].  Such forests in the
Bitterroot National Forest in Montana have a MFRI of 17 to 28 years
[14].  Fires at this frequency kill subalpine fir and keep these forests
dominated by seral conifers such as lodgepole pine, Douglas-fir, or
western larch.  Moist, middle and upper elevation subalpine fir habitat
types, however, generally experience high intensity stand-replacing
fires at intervals of 100 years or more.  Mean fire return intervals for
middle and upper elevation subalpine fir habitat types in several areas
are presented below:

Location                  Community dominants           MFRI    Reference
                                                       (years)
Kananaskis Park, AB      subalpine fir, spruce,          90       [12]
                         lodgepole pine        
northern Cascades, WA    subalpine fir                 154        [2]
northern Cascades, WA    subalpine fir-lodgepole pine  109        [2]
Olympic NP, WA           subalpine fir                 150        [116]
Yellowstone NP, WY       subalpine fir                 300-350    [98]
Coram Exp. Forest, nw MT western larch, Douglas-fir,   117-146    [129]
                         lodgepole pine, subalpine fir

Fuels and fire behavior:  The fuel structure in subalpine-fir-dominated
stands promotes highly destructive stand-destroying fires.  Fuel loads
in subalpine fir stands are greater than in lower elevation montane
stands because the cool and moist environment slows the decomposition of
organic matter allowing fuels to accumulate more rapidly [1].  Fuel beds
tend to be irregular, with over twice as much fuel accumulating under
the narrow-crowned trees as between them [116].  The needles are small
and fine and form a compact fuel bed in which fire spreads slowly [34].
These concentrated, slow burning fuels frequently produce flames high
enough to reach subalpine fir's low-growing dead branches [116].  Thus
crowning is common in subalpine fir stands.

Once a crown fire begins, it spreads easily because subalpine fir has a
tendency to grow in dense stands and has highly flammable foliage.  A
lightning strike on May 7, 1987, in a subalpine fir-mountain hemlock
stand in Mount Rainier National Park started a crown fire even though
the ground was still partially snow covered.  The fire spread slowly
through the tree crowns by (1) igniting lichens draped along the fine
branches, (2) preheating and igniting the foliage, and (3) spreading to
a nearby tree by igniting its lichens [62].

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

Subalpine fir is very fire sensitive and is often killed even by surface
fires.  Following timber harvest, on sites where subalpine fir is not a
preferred species, light surface fires may be used to kill subalpine
fir and promote the establishment of other conifers [93]. 

Fuels remain moist in many high elevation subalpine fir habitat types
during most of the year, leaving only a short time period during certain
years when prescribed burning can take place [63,91].

Subalpine fir seeds germinate poorly in soils under burned slash piles
[130] but readily germinate on mineral soil seedbeds prepared by
broadcast burning [16,107].

More info for the terms: cone, seed

High intensity crown fires which are common in subalpine fir forests,
kill all or nearly all seed trees within a burned area.  If subalpine
fir is to naturally regenerate on this type of burn, seeds must come
from adjacent unburned stands.  Because subalpine fir seeds are
dispersed over relatively short distances, initial seedling
establishment is restricted to the burn's edge.  Subalpine fir cone
production can be erratic from year to year, with the best regeneration
occurring during good seed crop years.

More info on this topic.

More info for the terms: phanerophyte, therophyte

   Undisturbed State: Phanerophyte (mesophanerophyte)
   Undisturbed State: Phanerophyte (microphanerophyte)
   Undisturbed State: Phanerophyte (nanophanerophyte) Krummholz form
   Burned or Clipped State: Therophyte

More info for the terms: association, climax, habitat type, tundra

Subalpine fir is a middle to upper elevation mountain conifer.  It
generally occupies sites with a short growing season caused by cold
winters, cool summers, frequent summer frosts, and heavy snowpack.  It
forms extensive forests between warm and dry lower elevation forests of
Douglas-fir, white fir (Abies concolor), grand fir, lodgepole pine, or
blue spruce (Picea pungens) and higher elevation alpine tundra
[23,29,112,125].  At its lower elevational limits, subalpine fir is
often restricted to streambottoms, ravines, frosty basins, or north
exposures.  It increasingly occupies westerly and easterly aspects with
increasing elevation and may occupy all aspects at upper timberline
[23,91].

Stand condition and associated conifers:  Throughout its range,
subalpine fir is most commonly associated with Engelmann spruce.  These
two species frequently occur as codominants forming widespread subalpine
forests.  In the central and southern Rocky Mountains, Engelmann spruce
commonly makes up 70 percent of overstory trees, with subalpine fir
dominating the understory [9].  Within spruce-fir forests of this
region, Engelmann spruce tends to be more important at higher elevations
and on wetter sites, while subalpine fir is more abundant on drier lower
elevation sites [9].  In the northern Rocky Mountains, subalpine fir
typically dominates climax stands, but Engelmann spruce becomes
increasingly important on moist, cool sites [23,91].  Other associates
which vary by latitude and elevation are listed below [39]:

Location              Elevation   Associates

northern Rocky Mtns   low         western white pine (Pinus monticola),
                                  Douglas-fir, western larch (Larix
                                  occidentalis), grand fir, western hemlock
                                  (Tsuga heterophylla), western redcedar
                                  (Thuja plicata)
                       high       lodgepole pine, subalpine larch (Larix
                                  lyallii), whitebark pine (Pinus
                                  albicaulis), mountain hemlock
central Rocky Mtns     low        lodgepole pine, Douglas-fir, aspen
                                  (Populus tremuloides), blue spruce
                       high       whitebark pine, limber pine (Pinus
                                  flexilis), bristlecone pine (P. aristata)
southern Rocky Mtns    low        white fir, Douglas-fir, blue spruce, aspen
                       high       corkbark fir
Cascade Mtns           low        Pacific silver fir, mountain hemlock,
                                  lodgepole pine 
                       high       mountain hemlock, whitebark pine

Understory associates:  Understory vegetation is extremely variable,
changing with elevation, exposure, and soil moisture.  Habitat type and
plant association guides describe characteristic understory plants for
differing sites.

Elevation:  Alexander and others [11] described the following
elevational ranges for subalpine fir:

Coast Range of southeastern Alaska - subalpine fir is found from sea
level to 3,500 feet (0-1,067 m). 

Coast Range and interior plateaus of Yukon Territory and British
Columbia - subalpine fir is found from 2,000 to 5,000 feet (610-1,524
m).

Olympic and Cascade Mountains of Washington and Oregon - subalpine fir
is generally found from 4,000 to 6,000 feet (1,219-1,829 m), but may be
found as low as 2,000 feet (610 m) along cold streambottoms and on lava
flows, and as high as 8,000 feet (2,438 m) on sheltered slopes.

Rocky Mountains of British Columbia and Alberta south of the Peace River
- subalpine fir is found from 3,000 to 7,000 feet (914-2,134 m) but is
more abundant above 5,000 feet (1,524 m).

Rocky Mountains of Montana and Idaho and associated ranges of eastern
Oregon and Washington - subalpine fir grows from 2,000 to 11,000 feet
(610-3,353 m) but is most common at 5,000 to 9,000 feet (1,524-2,743 m).

Rocky Mountains of Wyoming, Utah, and Colorado - subalpine fir occurs
from 8,000 to 11,500 feet (2,438-3,506 m) but is most common at 9,000 to
11,000 feet (2,743-3,353 m).

Rocky Mountains of New Mexico and Arizona - subalpine fir occurs from
8,000 to 12,000 feet (2,438-3,658 m) but is usually found on north
slopes from 9,500 to 11,000 feet (2,896-3,353 m).

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

   201  White spruce
   202  White spruce - paper birch
   205  Mountain hemlock
   206  Engelmann spruce - subalpine fir
   208  Whitebark pine
   209  Bristlecone pine
   210  Interior Douglas-fir
   212  Western larch
   213  Grand fir
   215  Western white pine
   216  Blue spruce
   217  Aspen
   218  Lodgepole pine
   219  Limber pine
   223  Sitka spruce
   224  Western hemlock
   226  Coastal true fir - hemlock
   253  Black spruce - white spruce

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

   FRES20  Douglas-fir
   FRES22  Western white pine
   FRES23  Fir - spruce
   FRES24  Hemlock - Sitka spruce
   FRES25  Larch
   FRES26  Lodgepole pine
   FRES44  Alpine

More info on this topic.

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

More info for the term: forest

   K004  Fir - hemlock forest
   K012  Douglas-fir forest
   K015  Western spruce - pine forest
   K018  Pine - Douglas-fir forest
   K020  Spruce - fir - Douglas-fir forest
   K021  Southwestern spruce - fir forest
   K052  Alpine meadows and barren

More info for the term: lichen

Subalpine fir is one of the least fire-resistant western conifers.  It
is very susceptible to fire because it has (1) thin bark that provides
little insulation for the cambium, (2) bark which ignites readily, (3)
shallow roots which are susceptible to soil heating, (4) low-growing
branches, (5) a tendency to grow in dense stands, (6) highly flammable
foliage, and (7) moderate to heavy lichen growth [37,111].

Subalpine fir forests are normally subject to highly destructive crown
fires that occur at 100-year or longer intervals.  Such fires typically
kill all subalpine fir trees.  Subalpine fir is also very susceptible to
surface fires because fine fuels which are often concentrated under
mature trees burn slowly and girdle the thin-barked bole [34].

More info for the terms: cover, woodland

Subalpine-fir-dominated stands generally do not produce enough forage
for livestock but do provide browse and cover for large and small
wildlife species.  Mule deer, elk, moose, woodland caribou, black bear,
and grizzly bear often use subalpine fir habitats as summer range
[10,23,113]].  Subalpine fir forests are generally not suitable winter
range for deer and elk because of heavy snowpack, but some lower
elevation subalpine fir habitat types are used by moose and woodland
caribou during the winter [23,61,89].  Subalpine fir forests support
numerous species of small mammals and birds.  The snowshoe hare, flying
squirrel, red squirrel, porcupine, pine marten, fisher, lynx, and
several species of mice, voles, chipmunks, and shrews all inhabit
subalpine fir forests [26,104,113].  Numerous species of birds nest and
feed in subalpine fir forests, including several woodpeckers,
flycatchers, kinglets, nuthatches, juncos, thrushes, chickadees,
crossbills, the pine siskin, owls, and grouse [104,113].

The young growth of subalpine fir is sometimes eaten by mule deer, elk,
bighorn sheep, and snowshoe hares, but it is not an important food item.
Subalpine fir comprises only a small portion of the summer diet of
mountain goats but can be a major food source in the winter and spring
[99].  Throughout much of Montana, Idaho, and Wyoming, subalpine fir is
an important winter food of moose [89].  On moose winter range near
Jackson Hole, Wyoming, an average of 13 to 18 percent of small subalpine
fir trees were browsed by moose, and 44 to 78 percent of the branches on
trees browsed were utilized [61].  In Yellowstone National Park, grizzly
bears sometimes strip the bark of subalpine fir to feed on the
underlying cambium [19].  The winter diet of blue grouse consists
primarily of conifer needles.  These grouse often winter in subalpine
stands and may feed heavily on the needles and buds of subalpine fir
[103,113].

Subalpine fir seeds are eaten by several species of small mammals and
birds.  Red squirrels eat seeds from cached subalpine fir cones [71].
Fir seeds are also eaten by chipmunks and mice.  Several birds,
including chickadees, nuthatches, crossbills, the pine siskin, and the
Clark's nutcracker remove and eat the seeds from fir cones [49,77].
Because subalpine fir seeds are large, comprising about 26 percent of a
cone's weight, they are an energy-efficient food source for small birds
[49].  Small birds may make considerable use of fir seeds, but their
foraging is scattered and sporadic throughout subalpine forests [49].

More info for the terms: climax, codominant, forest, grassland, series, shrubland, woodland

Forests in which subalpine fir attains climax dominance or codominance
are widespread throughout the mountains of western North America.  The
subalpine fir series generally occupies cold, high elevation mountain
forests.  Engelmann spruce (Picea engelmannii) is usually associated
with subalpine fir.  It occurs as either a climax codominant or as a
persistent, long-lived seral species in most subalpine fir habitat
types.

Published classification schemes listing subalpine fir as a dominant
part of the vegetation in habitat types (hts), community types (cts),
plant associations (pas), ecosystem associations (eas), site types (sts)
or dominance types (dts) are presented below:

Area                    Classification          Authority

AK: -----               general veg. cts        Viereck & Dyrness 1980
AZ: San Francisco       forest, alpine &
      Peaks RNA           meadow cts            Rominger & Paulik 1983
AZ, NM: -----           forest & woodland hts   Layser & Schubert 1979
        Apache, Gila,
          Cibola NFs    forest hts              Fitzhugh & others 1987
        s of Mogollon
          Rim           forest hts              Develice & Ludwig 1983b
n AZ, n NM              forest hts              Larson & Moir 1987
CO: Arapaho &
      Roosevelt NFs     forest hts              Hess & Alexander 1986
    Gunnison &
      Uncompahgre NFs   forest hts              Komarkova & others 1988
    Routt NF            forest hts              Hoffman & Alexander 1980
    White River-        grassland, shrubland,
      Arapaho NF          & forestland hts      Hess & Wasser 1982
    White River NF      forest hts              Hoffman & Alexander 1983
w CO                    riparian pas            Baker 1989a
ID: Sawtooth, White
      Cloud, Boulder,
      & Pioneer Mtns    general veg. cts        Schlatterer 1972
c ID                    forest hts              Steele & others 1981
n ID                    forest hts              Cooper & others 1987
se ID                   aspen cts               Mueggler & Campbell 1986
e ID, w WY              forest hts              Steele & others 1983
MT: -----               forest hts              Pfister & others 1977
    -----               riparian dts            Hansen & others 1988
c, e MT                 riparian cts, hts       Hansen & others 1990
nw MT                   riparian hts, cts       Boggs & others 1990
sw MT                   riparian rst, cts, hts  Hansen & others 1989
NM: Cibola NF           forest hts              Alexander & others 1987
    Lincoln NF          forest hts              Alexander & others 1984
n NM, s CO              forest hts              Develice & Ludwig 1983a
n NM, s CO              forest hts              Develice  & others 1986
OR: Wallowa-Whitman NF  steppe & forest pas     Johnson & Simon 1987
    Eagle Cap
      Wilderness        general veg. cts        Cole 1982
OR, WA: -----           general veg. cts        Franklin & Dyrness 1973
        Blue Mtns       general veg. pas        Hall 1973
UT: -----               aspen cts               Mueggler & Campbell 1986
c, s UT                 forest hts              Youngblood & Mauk 1985
n UT                    forest hts              Mauk & Henderson 1984
WA: Okanogan NF         forest pas              Williams & Lillybridge 1983
    Mount Rainier NP    forest pas              Franklin & others 1988   
    North Cascades NP   forest pas              Agee & Kertis 1987
e WA, n ID              forest hts, cts         Daubenmire & Daubenmire 1968
WY: Bridger-Teton NF    aspen cts               Youngblood & Mueggler 1981
    Medicine NF         forest hts              Alexander & others 1986
    Bighorn Mtns        forest hts              Hoffman & Alexander 1976
    Wind River Mtns     forest hts              Reed 1976

USFS R-2                general veg. pas        Johnston 1987
USFS R-2                general veg. hts,pas    Wasser & Hess 1982
USFS R-4                aspen cts               Mueggler 1988

w-c AB                  forest cts              Corns 1983
BC: -----               grassland, forest hts   McLean 1970
    -----               general veg. eas        Pojar & others 1984
nw BC                   forest eas              Haeussler & others 1985

          

More info for the term: tree

Tree

More info for the terms: seed, seed tree, selection, tree, tussock, woodland

Timber harvest:  Shelterwood and individual tree selection silvicultural
methods favor subalpine fir over Engelmann spruce, lodgepole pine (Pinus
contorta), and Douglas-fir (Pseudotsuga menziesii); clearcutting and
group selection cutting favor subalpine fir over Pacific silver fir
(Abies amabilis), grand fir (A. grandis), and mountain hemlock (Tsuga
mertensiana) where they grow together [11].  The seed tree method is
generally not used because of the susceptibility of subalpine fir to
windthrow [11].  In the Rocky Mountains, clearcutting and shelterwood
cutting have been the most commonly used harvesting methods in
old-growth Engelmann spruce-subalpine fir stands because these stands
tend to be even-aged and overmature [8].  Uneven-aged silviculture can
pose a problem because residual subalpine fir trees damaged during
thinning operations are susceptible to attack by decay fungi.
Silvicultural systems and cutting methods for managing subalpine fir
have been discussed in detail [7,8,9,11].

Pests and diseases:  Subalpine fir is attacked by numerous insects.  The
most destructive seem to be the western spruce budworm, western balsam
bark beetle, and balsam woolly aphid [11].  Subalpine fir is one of the
most common hosts of the western spruce budworm.  This pest generally
attacks low and middle elevation subalpine fir forests but is largely
absent from high elevation forests [21].  The balsam woolly aphid has
virtually eliminated subalpine fir from some stands in the Cascades
[11].  Other insect pests include the Douglas-fir tussock moth, western
black-headed budworm, and fir engraver beetle.

Subalpine fir is susceptible to annosus root disease, caused by the
fungus Heterobasidion annosum, which results in root and butt decay.
Outbreaks of this disease are often centered around large 20-year-old or
older fir stumps that contain the fungus' fruiting bodies [102].
Subalpine fir is most seriously affected by this disease in the northern
and central Rocky Mountains [123], and is affected to a lesser extent in
the Pacific Northwest [102].  Subalpine fir is susceptible to several
other wood rotting fungi that cause heart, trunk, butt, or root rots,
including brown stringy rot, red heart rot, red ring rot, shoestring
rot, brown cubical rot, white spongy root rot, and white pocket rot
[39].  Trees weakened by wood rots often become infested by fir engraver
beetles and usually succumb to windfall and breakage [11].  Fir broom
rust is another common problem in Engelmann spruce-subalpine fir stands
and causes bole deformation, spike tops and wind breakage, and makes
trees more susceptible to decay fungi [11].

Habitat for threatened and endangered species:  Old-growth subalpine fir
stands in northern Idaho may provide critical habitat for woodland
caribou [23].  Numerous subalpine fir habitat types, especially those
containing huckleberries (Vaccinium spp.), provide critical habitat for
grizzly bears [127].

Subalpine fir is low in protein value but fair in energy value [30].
Percent composition of subalpine fir browse collected near Jackson Hole,
Wyoming, was as follows [61]:

  date              crude        ether       crude      nitrogen
collected          protein      extract      fiber    free extract
 11/25              5.57         7.53        20.19      50.26

A study in Montana found the following concentration of elements in
subalpine fir needles and twigs [110]:

      1-yr-old green needles    twigs < 0.25 inch (0.64 cm) in diameter
     (micrograms/gram [mean])           (micrograms/gram [mean])
Ca             9722                               5840
Cu                7.4                                7.9
Fe               64                                182
K              5553                               7031
Mg              819                               1038
Mn             1020                                587
N             10690                               4962
Na              103                                124
P              1450                               2254
Zn               43                                  5
          (percent [mean])                    (percent [mean])
Ash               3.5                                3.5

     AK  AZ  CO  ID  MT  NV  NM  OR  UT  WA
     WY  AB  BC  YT

Subalpine fir is sometimes used as a landscape plant to produce
screenings or windbreaks [114].  In the Pacific Northwest it is
sometimes transplanted into rock gardens or simulated subalpine settings
[69].

Native Americans used various parts of subalpine fir for numerous
purposes.  A hair tonic was prepared by mixing powdered needles with
deer grease.  Finely ground needles were also sprinkled on open cuts.
Sticky resin collected from the bark was boiled and used as an
antiseptic for wounds or as a tea for colds.  Boughs were placed in
rooms for their aroma, and pulverized needles were used as a body scent
or as perfume for clothing [53].

Resin from the bark is used in the optical industry and in laboratories
as a cement for lenses and microscope slides [71].

The palatability of subalpine fir to domestic livestock is low [30].
Its palatability to big game animals is generally low also, but in some
locations it is highly palatable to moose and mountain goats during
winter and spring [89,99].  The seeds are palatable to numerous small
mammal species [77].  Red squirrels generally eat subalpine fir seeds
after other cached conifer seeds have been consumed [71].  The needles
are highly palatable to blue grouse.

The relish and degree of use shown by livestock and wildlife species for
subalpine fir in several western states is rated as follows
[30,61,89,96]:

                       CO    MT    WY    UT    ID
Cattle                poor  poor  poor  poor  ----
Sheep                 poor  poor  poor  poor  ----
Horses                poor  poor  poor  poor  ----
Pronghorn             ----  ----  poor  poor  ----
Elk                   ----  poor  poor  poor  ----
Moose                 ----  good  good  ----  fair
Mule deer             ----  poor  poor  poor  ----
White-tailed deer     ----  ----  poor  ----  ----
Small mammals         ----  fair  fair  good  ----
Small nongame birds   ----  ----  fair  good  ----
Upland game birds     ----  fair  fair  good  ----
Waterfowl             ----  ----  poor  poor  ----

More info on this topic.

More info for the terms: cone, phenology, seed

Subalpine fir requires 2 years to complete its reproductive cycle [115].
Cones are initiated in the spring of the first year as microscopic
primordia within vegetative buds.  Bud differentiation occurs in
midsummer, and separate seed-cone and pollen-cone buds develop until
each becomes dormant in the fall [115].  During the spring of the second
year, cone buds resume growth and conelets are recognizable in the early
spring.  During the second year, reproduction phenology generally
proceeds as follows:

Phenological event  Location      Timing of event           Reference

flowering           sw MT, nw WY   mid-June - early July    
cones full size         "               late August         
seeds dispersed         "         early Sept - early Oct     [41,101]

flowering           nw MT, n ID   mid-June - early July     
cones full size         "         late July - early Aug     
seeds dispersed         "               mid-Sept             [41,101]

flowering               OR         late May - early July    
seed dispersal          "             early Oct               [41]

male bud burst      Linn, OR         early to mid-May       
female bud burst        "            mid to late May        
pollen shed             "                 June              
seed dispersal begins   "              early October          [45]

flowering        AZ, San Fran.Peaks     late June           
cone ripening           "           mid-Sept - early Oct    
seed dispersal          "           late Sept - early Oct     [41]

More info for the terms: cone, seed, tree, wildfire

Following fire, subalpine fir reestablishes via seeds dispersed by wind
from trees surviving in protected pockets or from trees adjacent to
burned areas.  Subalpine fir readily establishes on burned mineral soil
seedbeds [107].  Ash does not affect germination, but if it is deep, it
can prevent a seedling's roots from reaching mineral soil [85].
Although seedling establishment is often favored by shade, it will
establish in full sunlight following fire [87].

The rate of establishment is quite variable, and depends on the
proximity of the seed source (because the heavy seeds are dispersed over
short distances) and seed production during the year of the fire and
immediate postfire years.  In general, subalpine fir seedling
establishment is very slow in areas suffering large, continuous crown
fires but is relatively rapid on small burned-over areas where a seed
source is nearby [90,124,128].  Three years after a late August wildfire
in northern Colorado, in a dense, mature stand composed of Engelmann
spruce, subalpine fir, and lodgepole pine, subalpine fir had established
15,200 seedlings per acre (37,500/ha) on small burns that were less than
one-tenth of an acre in size.  But on areas within the middle of the
main burn, subalpine fir had established only 12 seedling per acre
(30/ha) 3 years after the fire [16].  In Colorado, Peet [90] found a
75-year-old burn that had few conifer seedlings even though an
old-growth subalpine fir-Engelmann spruce stand was 218 yards (200 m)
away.

Reinvasion into large burns is slow because much of the seed source is
destroyed.  However, sometimes sporadic survivors provide a limited seed
source so that a small number of seedlings establish quickly following
fire.  When this occurs, large quantities of seeds are dispersed several
decades later as the early invading seedlings mature and reach cone
bearing age [128].

On areas where subalpine fir is abundant and lodgepole pine scarce
before burning, subalpine fir establishes quickly following fire if
sufficient numbers of seed trees survive or are near the burn.  However,
if lodgepole pine is present prior to burning, it usually seeds in
aggressively and assumes a dominant role because it quickly overtops any
fir seeding in at the same time [34].  Subalpine fir can be suppressed
for several decades in seral lodgepole stands which develop following
fire; one-hundred-year-old individuals may be only 3 feet (0.9 m) tall
[90].  It may take 50 to 150 years after a fire for substantial
subalpine fir establishment under dense lodgepole pine stands
[18,109,128].

In the Olympic Mountains, tree seedling establishment following fires in
closed mountain hemlock-subalpine fir forests was higher during wet
growing seasons than during dry growing seasons.  Establishment rates
were higher near the edge of a fire or near survivors than in areas
removed from a seed source [4].  On many burned areas, subalpine fir did
not establish seedlings for several years because of poor seed crops.
On some burns there was a lag time of 40 to 50 years after fire before
there was substantial seedling establishment.  This was a result of
early invading trees maturing and dispersing seeds [4].

High elevation subalpine fir stands that have burned often remain open
for several decades or more [18,31].  The harsh environment near
treeline makes it difficult for tree seedlings to establish and survive
[18].  Grasses and sedges may form a mat in subalpine meadows which
prevents tree seeds from reaching mineral soil [109].

More info for the terms: secondary colonizer, seed

   crown-stored residual colonizer; short-viability seed in on-site cones
   secondary colonizer; off-site seed carried to site after year 2
   off-site colonizer; seed carried by wind; postfire years 1 and 2

More info for the terms: climax, duff, forest, layering, litter, natural, seed, stratification, tree

Cone and seed production:  Subalpine fir can begin producing cones when
20 years old and 4 or 5 feet (1.2-1.5 m) tall, but under closed forest
conditions seed production is generally not significant until trees are
older and taller [11].  Corkbark fir generally does not produce cones
until about 50 years old [39].  Nearly all cones are produced on the
uppermost part of the crown.  Maximum seed production is by dominant
trees between 150 and 200 years old [39].  Yearly seed production is
very erratic; good seed crops are produced every 3 to 5 years, with
light crops or crop failures in between [39,40,54,86].  Corkbark fir is
also a poor seed producer, having more crop failure years than good seed
crop years [9].  Subalpine fir averages 34,800 seeds per pound
(76,700/kg), while corkbark fir seeds average 22,300 per pound
(49,150/kg) [41].

Seed predation:  Insect pests reduce seed yields by feeding on cones and
seeds; however, the magnitude of loss is variable [11].  Red squirrels
cut and cache large quantities of subalpine fir cones [9].  After
dispersal, numerous small rodents and birds consume seeds from the
ground.

Dispersal:  Mature subalpine and corkbark fir seeds have a large wing
and are dispersed primarily by wind in the fall as cones disintegrate on
the tree.  Seeds travel primarily in the direction of prevailing winds,
but upslope drafts can influence dispersal at low and middle elevations
[9].  Studies in Colorado showed that about one-half of subalpine fir
seeds dispersed into clearcuts fell within 100 feet (30 m) of the
clearcut's windward edge, while the remainder fell within 260 feet (80
m) of the edge [86].  Some seeds are also dispersed by red squirrels
which cut and cache cones before they disintegrate; seeds commonly
germinate from these middens, forming thickets [71].

Germination and viability:  Seeds overwinter under or in snow.  This
cold, moist stratification is required for germination [41].
Germination begins in the spring a few days after snowmelt and is
usually completed within a few weeks [9,106].  Percent germination is
low due to unsound seed; about 31 to 38 percent for subalpine fir and 26
to 33 percent for corkbark fir [39,41].  Under natural conditions seeds
remain viable for 1 year [41].  Stratification procedures for stored
seeds have been described in detail [41,74].

Seedling establishment and survival:  Seedlings establish best on
mineral soil seedbeds but will also establish on other surfaces
including litter, duff, and decaying wood [11].  Because Engelmann
spruce requires a mineral soil seedbed, subalpine fir seedlings usually
outnumber spruce seedlings in the understory of spruce-fir stands.
Thus, even though it is short-lived, many ecologists consider subalpine
fir better able to regenerate under climax conditions than Engelmann
spruce.  Subalpine fir is very shade tolerant and easily establishes
under a closed canopy.  Throughout the Rocky Mountains subalpine fir is
reproducing abundantly under conditions of dense shade and is often
abundant as seedlings and saplings in spruce-fir forests, even where
Engelmann spruce dominates the overstory [11,67].

At higher elevations, seedling survival is sometimes greater on duff
seedbeds because the duff helps protect seedlings from high-intensity
summer rain storms and frost heaving [35].  At lower elevations,
seedling densities are often greater on mineral soils [35].  In a
spruce-fir forest in southeastern Wyoming, Knapp and Smith [67] found
that 42 percent of subalpine fir seedlings were on litter deeper than 1
inch (2.5 cm), compared with only 5 percent of Engelmann spruce
seedlings.  Subalpine fir is able to establish in duff because of its
rapid root growth.  Comparing seedlings grown in a greenhouse, subalpine
fir's taproot length (29 mm) 2 weeks after germination was over 200
percent greater than the taproot length of Engelmann spruce (9.4 mm)
[67].

Growth:  Subalpine fir seedlings grow very slowly.  One-year-old
seedlings are frequently less than 1 inch (2.5 cm) tall [11].  One study
found 15-year-old seedlings averaged only 11 inches (28 cm) in height on
burned-over slopes, 10 inches (25 cm) on cut-over dry slopes, and 6
inches (15 cm) on cut-over wet flats [11].  Under favorable conditions
trees reach a height of 4 to 5 feet (1.2-1.5 m) in 20 to 40 years [11].
Under a closed canopy, trees 4 to 6 feet tall (1.2-1.8 m) are often 35
to 50 years old.

Vegetative reproduction:  Near timberline subalpine fir frequently
reproduces by layering, probably as a result of heavy snow, wind, and
cold temperatures which restrict growth away from the ground.  Layering
often results in clusters of subalpine fir growing near timberline [13].
Under closed forest canopy, reproduction by layering is negligible.

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    1  Northern Pacific Border
    2  Cascade Mountains
    5  Columbia Plateau
    6  Upper Basin and Range
    8  Northern Rocky Mountains
    9  Middle Rocky Mountains
   11  Southern Rocky Mountains
   12  Colorado Plateau

fall/severe

More info for the terms: duff, fuel, snag

The burned site is a southwest facing gentle slope at an elevation of
5,596 to 5,776 feet (1,706-1,761 m).  A total of 27 acres (10.9 ha) were
burned. 

Climate:  The climate is typical of most areas within the subalpine
zone.  The winters are cold and wet and the summers cool and dry.  Frost
and freezing temperatures can occur during any month of the year.  Over
70 percent of precipitation falls as snow between October and March.

Soil and duff:  The two stands have similar soils, but the soil in the
snag area is more fertile and better developed.  In both areas soils
are derived from basalt residium, have a clay-loam texture, and average
6 inches (15.2 cm) deep.  The effective rooting depth was about 20
inches (51 cm) in the thicket area, and 20 to 40 inches (51-102 cm) in
the snag area.  On both areas, duff was generally from 1 to 4 inches
(0.4-1.6 cm) thick.  The mean depth of duff was 2.3 inches (5.94 cm) on
the thicket area, and 1.9 inches (4.92 cm) on the snag area. 

Fuel loading:  Prior to burning, mean fuel loads were as follows:

          fuels                    thicket area          snag area
                                tons/acre tonnes/ha  tons/acre tonnes/ha

dead and down wood
 0.0-0.25 inch (0.0-0.6 cm)        0.6       1.3        0.9       2.0
 0.26-0.99 inch (0.61-2.5 cm)      2.1       4.6        2.9       6.4
 1.0-3.0 inches (2.6-7.6 cm)       4.4       9.8        5.1      11.4
 > 3.0 inches (7.6 cm) rotten     17.4      38.9       30.9      69.2
 > 3.0 inches (7.6 cm) solid      17.0      38.1       50.1     112.2
litter                            41.4      92.7       89.8     201.2
duff                              32.5      72.8       30.0      67.1

More info on this topic.

More info for the terms: climax, herbaceous, seed, severity, succession

In the Rocky Mountains, subalpine fir is a shade-tolerant climax species
favored by long fire-free intervals.  Its seedlings outcompete spruces,
lodgepole pine, and Douglas-fir when light intensities are less than 50
percent of full sunlight, but cannot compete with these conifers under
brighter light [11].  In Montana and Idaho and in the mountains of
eastern Washington and eastern Oregon, subalpine fir often forms pure
stands at climax, but it may also mix with Engelmann spruce, which,
although considered to be seral to subalpine fir, outlives it and
persists to climax.  In the Rocky Mountains north and south of Montana
and Idaho, Engelmann spruce and subalpine fir may codominate at climax
[11].

Throughout much of the Cascade Mountains subalpine fir grows as a
shade-intolerant, seral species and is gradually replaced by more
shade-tolerant associates such as Pacific silver fir, grand fir, and
mountain hemlock [43].  It often invades recently disturbed areas with
lodgepole pine.  It also pioneers harsh sites on raw geologically young
surfaces such as lava flows and talus slopes and on climatically harsh
sites near timberline [43].

In areas where subalpine fir is a climax dominant, succession following
disturbance varies depending upon the severity and type of disturbance,
elevation, and the availability of conifer seeds.  Subalpine fir may
establish immediately following disturbances if mature trees survive to
provide seeds and seral species such as lodgepole pine and aspen are
scarce.  Near treeline, it may take 100 years or more for subalpine fir
to establish seedlings following fire because an increase in herbaceous
species prevents seeds from reaching mineral soil and the harsh climate
kills many seedlings that do establish [18,109].  Aspen and lodgepole
pine are the most common seral species.  They often form pure stands and
completely dominate low and middle elevation stands within the subalpine
fir zone following large fires [5,68].  These species grow rapidly and
quickly overtop any subalpine fir seedlings that may establish at the
same time.  Aspen stands can sometimes persist for decades or even
centuries when conifer seed trees are eliminated [29].  When lodgepole
pine establishes immediately following stand-destroying fires, it often
forms even-aged dense stands that dominate for 100 to 300 years.
Because it is very shade tolerant, subalpine fir eventually establishes
under the pine canopy, usually within 100 years, and attains dominance
as the pine stand begins to break up [90,98].

In many of the warmer and lower elevation subalpine fir habitat types,
subalpine fir has not achieved climax dominance because of repeated
fires which favor shade-intolerant seral conifers.  Many of these
habitat types are in midsuccessional stages.  Lodgepole pine, western
larch, western white pine, or Douglas-fir dominate the overstory, but
subalpine fir seedlings and saplings occur in the understory [93,113].

Abies balsamea ssp. lasiocarpa (Hook.) Boivin
Abies balsamea var. fallax (Engelm.) Boivin

The genus Abies consists of about 40 species of evergreen trees found in
the northern hemisphere. Nine species of Abies, including subalpine
fir, are native to the United States [75]. The currently accepted
scientific name of subalpine fir is Abies lasiocarpa (Hook.) Nutt.
[75]. Subalpine fir is widely distributed and exhibits geographic
variation. Two varieties are recognized based on morphological
differences [75]:

Abies lasiocarpa var. arizonica, corkbark fir

Abies lasiocarpa var. lasiocarpa, typical variety of subalpine fir

Subalpine fir hybridizes with balsam fir (A. balsamea) where their
ranges overlap in the Canadian Rockies [41].

More info for the terms: forest, seed, tree

Subalpine fir can be planted on disturbed sites within forest vegetation
types where it naturally occurs [92].  It is generally recommended for
cool and moist sites within subalpine areas [120].  Its erosion control
potential is listed as medium in Utah and Montana, and high in Colorado
[30].  Because this wide-ranging tree exhibits a large degree of genetic
variation, seed or nursery stock for rehabilitation projects should come
from a local source.  Transplanting nursery stock is generally more
successful than direct seeding [92].  Seedlings exhibit very slow
initial growth and are therefore usually outplanted as 2- to 3-year-old
seedlings [41].  Wild seedlings may also be transplanted [120].  A
maximum spacing of 10 x 10 feet (3 x 3 m) has been recommended for
seedlings or transplants [120].  Methods for collecting, processing,
testing, storing, and planting subalpine fir seeds have been discussed
in detail [32,41].

Subalpine fir wood is odorless, light-weight, soft, and low in bending
and compressive strength [11].  It is easy to work, glues well, and
holds nails and screws fairly well.  The wood is primarily used for
products such as lumber for home construction and for prefabricated wood
products [9].  Subalpine fir has excellent pulping properties [9].  Use
for poles and pilings requires large amounts of preservatives because
the wood decays rapidly [108].