Cascade Fir

Pacific silver fir
amabilis fir
Cascades fir
lovely fir
silver fir

More info for the term: cover

The dense growth of Pacific silver fir provides hiding, cover, and
thermal protection for wildlife [22].

More info for the term: monoecious

Pacific silver fir is a monoecious, long-lived, native conifer
[14,24,38,66,68]. At maturity, it can reach heights of 100 to 230 feet
(30-70 m) and diameters of 36 to 44 inches (90-110 cm) [24,26,38]. The
average maximum age for Pacific silver fir is 400 to 500 years on good
sites, and 250 to 350 years on more adverse sites. The maximum recorded
age is 540 years [14,59]. As Pacific silver fir becomes older, growth
is commonly deformed [57]. The crown is rigid and symmetrical with
lateral branches perpendicular to the stem [14]. Young trees have
resin-filled blisters protruding from the smooth, thin bark. The bark
of older trees is rough textured and flaky [6].

The needles grow from opposite sides of the branch, spreading
horizontally or brushed forward. The top is flat, grooved, and
"lustrous green", and the underside is stomatiferous and silvery white
[6,38]. Pacific silver fir has a second type of foliage on the
uppermost, cone-bearing branches. These needles are very sharp and
curved. The cones are stiffly erect, barrel shaped, and 3.5 to 6 inches
(8.9-15.2 cm) long [6].

Pacific silver fir occurs from extreme southeastern Alaska south through
western British Columbia, the Cascade Range of Washington and Oregon, to
northwestern California [6,7,51,55,60]. Pacific silver fir is also
found in the Olympic Mountains of Washington [6,7,38].

More info for the terms: fire frequency, fire interval, fire regime, frequency, mean fire interval, severity

In the Pacific silver fir zone, fires are infrequent (fire interval is
500 years) because of the humidity and the high levels of precipitation.
Surface fires are usually of low severity [69]. Some stands of Pacific
silver fir show no evidence of having burned. Fire frequency is a
limiting factor in the range of Pacific silver fir [69]. Pacific silver
fir is a fire-avoiding species throughout all stages of its life [72].
It is extremely fire sensitive primarily because its thin bark and
shallow roots [26]. Its foliage is highly flammable [50]. The mean
fire interval for Pacific silver fir as a primary dominant is 192 years
[1].

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

More info for the term: natural

Slash burning and stump removal decrease site preparation cost [56] but
have considerable repercussions. Slash burning has negative effects on
higher elevation ecosystems because of their low productivity and the
difficulty of replanting [57]. It also destroys advance regeneration
and delays natural regeneration [23]. Ruth [57] states, "it is good
insurance" to protect advance regeneration in these higher elevation
stands. These areas have a short burning season.

Miller and Bigley [46] found that slash burning decreases the number of
conifers, including Pacific silver fir. Logging of Pacific silver fir
leaves a high residue volume which can become a high fire hazard. Some
ways to reduce slash loadings and fire hazard are to cut lower volume or
younger stands, and use more volume or yard cull logs to encourage
utilization (which is currently practiced on federal lands). These
practices may reduce the effects of slash burning on site productivity
and stand development [46].

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More info for the term: phanerophyte

Phanerophyte

More info for the terms: fern, herbaceous, shrub, vine

The climate throughout the range of Pacific silver fir is maritime to
submaritime [14,41]. Pacific silver fir is usually submontane to
subalpine [27,41]. It thrives in areas that receive a great deal of
precipitation. Average annual precipitation ranges between 38 and 262
inches (965-6650 mm), mostly in the form of snow [14,22,27,42]. The
average winter temperature is 26 to 29.8 degrees Fahrenheit (-3.2 to
-1.7 deg C), and the average summer temperature is 57.2 to 58.8 degrees
Fahrenheit (14-14.9 deg C) [14,71]. Pacific silver fir is absent in
coastal areas with dry summers [59]. There is a correlation between
growth, snow-free period, days above a certain temperature, absence of
frost pockets, and preferable sites for Pacific silver fir [32].
Pacific silver fir has a mild frost tolerance and poor frozen soil
tolerance because of its need for water during the winter [22,51].

Pacific silver fir is an indicator of very moist soils. It occurs on
soils in the orders Alfisols, Entisols, Inceptisols, Histosols, and
Spodosols [51,67]. Soil parent materials include basalt, glacial till,
volcanic ash, pumice, and sedimentary rock [31,51,52]. Pacific silver
fir can grow where the water table is near the surface during the
growing season if the soil is well aerated, thick, and/or with wood
accumulations on top of the mineral soil [59]. Growth is successful
with thick humus present [59]. Soils are generally shallow, but soil
depth varies from 1.2 to 12 inches (3-30 cm) [27]. Soils are acidic in
the rooting zone (pH 5) [41]. Whatever the soil type, an adequate,
year-round water supply is very important. Often nitrogen and
occassionally sulfur are limiting elements in soils [32]. Soils rich in
magnesium and calcium indicate good sites for Pacific silver fir [42].

The elevation at which Pacific silver fir grows is quite variable. It
is more common at higher elevations but grows faster at lower elevations
[59]. Pacific silver fir occurs at a maximum of 7,000 feet (2,120 m) in
the southern part of its range and at a maximum of 1,000 feet (330 m) in
the northern part of its range [14,22,24,27,51].

Overstory associates not mentioned in Distribution and Occurrence
include noble fir (Abies procera), Alaska cedar (Chamaecyparis
nootkatensis), Shasta red fir (Abies magnifica var. shastensis), and
western larch (Larix occidentalis) [9.14,27,51,60]. Shrub understory
includes huckleberry (Vaccinium spp.), Cascades azalea (Rhododendron
albiflorum), devils club (Oplopanax horridum), copper bush (Cladothanus
pyrolaeflorus), rustyleaf menziesia (Menziesia ferruginea), salal
(Gaultheria shallon), vine maple (Acer circatum), and Oregon-grape
(Berberis nervosa) [9,12,15,28,52]. Herbaceous species are beargrass
(Xerophyllum tenax), bunchberry (Cornus canadensis), twinflower (Linnea
borealis), queenscup beadlily (Clintonia uniflora), dwarf blackberry
(Rubus lasiococcus), rosy twistedstalk (Streptopus roseus), coolwort
foamflower (Tiarella unifoliata), deer fern (Blechnum spicant),
salmonberry (Rubus spectabilis), vanillaleaf (Achlys spp.), and
evergreen violet (Viola sempervirens) [9,12,14,28,52].

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

205 Mountain hemlock
206 Engelmann spruce - subalpine fir
213 Grand fir
215 Western white pine
221 Red alder
223 Sitka spruce
224 Western hemlock
225 Western hemlock - Sitka spruce
226 Coastal true fir - hemlock
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock

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

FRES20 Douglas-fir
FRES22 Western white pine
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce

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

More info for the term: forest

K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - Douglas-fir forest
K004 Fir - hemlock forest
K005 Mixed conifer forest
K012 Douglas-fir forest
K013 Cedar - hemlock - pine forest
K014 Grand fir - Douglas-fir forest
K015 Western spruce - fir forest

More info for the term: forest

Pacific silver fir has a low fire tolerance and is usually killed by any
forest fire [6,50,69].

More info for the term: selection

Old-growth stands provide good mountain goat habitat [70]. Northern
spotted owls are dependent on the availability of old-growth stands for
nest site selection and sufficient prey [54]. Other species with a
preference for old-growth stands include Vaux's swift, fisher, western
red-backed vole, and Olympic salamander [60]. Small nongame birds
prefer late seral or old-growth Pacific silver fir stands [39].

The seeds of Pacific silver fir are eaten by birds, rodents, and
squirrels [59,63]. Pacific silver fir is the least preferred of trees
browsed by elk [33].

More info for the terms: association, climax, codominant, forest

Pacific silver fir commonly occurs in late seral or climax mixed-conifer
stands [52]. Throughout its range the most commonly associated conifer
is western hemlock (Tsuga heterophylla). Pacific silver fir also
reportedly grows in extensive pure stands in parts of the southern
Washington Cascade Range [14]. Below are publications in which Pacific
silver fir is listed as a dominant or codominant species:

Preliminary plant associations of the southern Oregon Cascade Province [9]
Preliminary classification of forest communities in the central portion
of the western Cascades in Oregon [16]
Forest communities of Mount Rainier National Park [28]
Plant association of Mount Hood and Willamette National Forests of Oregon [35]
Forest communities of northern California [55]
Plant associations for the western hemlock zone [64]
Preliminary classification systems for the vegetation of Alaska [68].

More info for the term: tree

Tree

More info for the terms: association, cone, density, duff, forest, phase, presence, root collar, seed, selection, severity, stratification, tree, tussock

Rotation periods for Pacific silver fir vary, depending on management
objectives. For mountain goat habitat, the recommended rotation period
is 90 to 110 years [70]. For other nontimber (i.e. recreational, etc.)
benefits, the suggested rotation period is 150 to 200 years. Commercial
rotations are seldom longer than 110 years [70]. After release by
logging or windfall, suppressed trees respond with immediate and
substantial growth [59]. At lower elevations in the Pacific silver fir
zone, Pacific silver fir usually sun scalds when used as leave tree in
shelterwood cuttings [26]. Sudden exposure to sunlight temporarily
reduces growth. By the third season, the exposed trees are growing
faster than those trees at the stand edge. As many as seven growing
seasons may be needed for Pacific silver fir to reach maximum rates of
branch and height growth [65]. The shade tolerance of Pacific silver
fir makes it a good choice for the selection method. The disadvantage
of this practice is that it appears to encourage disease [36].

The timing of cone collection (mid to late August) is important because
cones disintegrate as they mature. Felling and topping are not
successful collection methods. The cones are susceptible to molding and
heat build-up if sacked when wet [18]. Calcid flies (Pregastigmus spp.)
infect cones of Pacific silver fir [59]. Franklin [24] discusses a cone
drying schedule and seed storage conditions. Seeds are delicate and
their coats may be damaged when drying [16]. Edwards [17] reviews
techniques of seed extraction, viability, and germination testing.
Cleaned seeds range from 17,200 to 45,860 seeds per pound (7,800-20,800
seeds/kg) [14], and average 11,000 to 13,800 seeds per pound
(4,590-6,210 seeds/kg) [24]. A stratification period of 21 to 28 days
is required. Seeds should be sown in spring at a density of 62.5 to 125
per acre (25-50 per ha) and approximately 0.25 inch (0.64 cm) deep,
depending on the site [24]. Arnott and Mathews [7] discuss nursery
practice for Pacific silver fir. Highest stocking can be achieved on
bare soil [34]. Seedlings planted in logged areas have done poorly [6].

Gessel and Klock [31] report that fertilizer contributes significantly
to growth of Pacific silver fir on poor sites, but Packee and others
[51] disagree. During the seedling stage when growth is slow,
fertilizer may be more effective than during other stages [52]. The
application of nitrates are more beneficial to Pacific silver fir than
ammonia compounds [31,42,51]. Fertilizer combined with thinning results
in accelerated volume and radial growth [31].

Herbicides have various effects on Pacific silver fir. The effect of
glyphosate and granular and liquid hexazinone had little effect. 2,4-D
ester, when applied at maximum rates in spring and late summer, had a
moderate effect on Pacific silver fir. Triclopyr ester had no effect
when applied in summer [10].

Pacific silver fir is damaged by mountain beaver, black bear, and
porcupine, which increases susceptibility to pathogens [56]. Wounds
result in wetwood, circular or radial shake, and frost cracks [3].

Pacific silver fir is among those species that are most seriously
affected by annosus root disease (Heterobasidion annosum). The
incidence of fungal infestations is higher in stands 200 years or older
than in younger stands [14]. Often a rotation of 40 to 120 years and
minimization of wounding trees will reduce intermediate entry of the
pathogen [22]. Airborne infection of Pacific silver fir is high
year-round [14]. Annosus root disease infects trees when roots grow in
contact with infected fungus food base. Other trees become infected
through root contacts. Air-borne spores colonize wounds up to 1 month
old [62]. Trees with this fungus show butt rot, retarded leader growth,
sparse and chloritic foliage, and distress cone crops; mortality may
occur [22,55]. Young stands can have high infection levels with low
severity damage [70]. The fungus and tree can "wall off" each other,
but once the tree becomes weakened, the fungus will invade [22].

After being weakened by annosus root disease, infestation by
fir-engraver beetle (Scolylus ventralis), silver fir beetle
(Pseudohylesinus sericeus), or fir root bark beetle (Pseudohylesinus
granulalus) is frequent [14,22,55]. When beetle populations are high,
Pacific silver fir may be attacked and killed before symptoms of
infection are found. These effects are enhanced during a drought [55].
Annosus root disease also causes stem decay [22].

The most reliable way to diagnose Annosus root disease is by the
presence of conks, or fruiting bodies, found in the duff layer at the
root collar on the outer bark. Ectotrophic mycelium on the roots cannot
be used in diagnosing annosus root disease [55].

To prevent damage to trees during logging, options include using
rubber-tired skidders, working with a proven crew, and afterwards,
treating remaining stumps with a registered pesticide to prevent its use
as a food source [62]. At the time of logging, stump removal to reduce
innoculum in the soil is useful in preventing further contamination
[62]. Borax application can be part of timber sales contracts when this
treatment is considered appropriate [70]. Saplings and pole-sized trees
are too small to be effective innoculum sources. Management should
involve reducing mortality, thinning fir trees at least 25 feet (7.5 m)
from dead trees, and minimizing wounding during salvage logging [22].

Armillaria (Armillaria ostoyae) is often a secondary pathogen of trees
infected with annosus root disease [55]. Pacific silver fir is
moderately susceptible to Armillaria. In stands with smaller trees,
thinning those within 25 feet (7.5 m) of dead trees, reducing mortality,
and minimizing wounding is helpful. Prescribed burning may slow
Armillaria growth [22]. Shoestring rot (Armillaria mellea) is also
detrimental to Pacific silver fir [14].

Fungi found in advance regeneration of Pacific silver fir are Indian
paint fungus (Echinodontium tinctorium) and Stereum sanguinolentum [20].
Indian paint fungus has been located on healthy stems and encased branch
piths of suppressed Pacific silver fir. Decay is commonly found near
wounds [4]. Infection sites include small diameter branch stubs between
50 and 60 years of age [4]. Indian paint fungus has a dormant phase,
which occurs when wounded tissues heal [4]. When trees receive a new
injury, the fungus resumes growth [3]. Indian paint fungus is most
easily recognized by the presence of conks or slow decay in old large
wounds [22]. Stand rotation should be 150 years or less and wound
reduction activities should be practiced [22]. Filip and Schmitt [2]
discuss color recognition of Indian paint fungus and planning and
operational activities.

Pacific silver fir is moderately susceptible to laminated root rot
(Phellinus weirii), which creates forest patches of damaged or dead
trees when abundant [15]. Infected trees in sawtimber-sized stands
should be removed, followed with stump removal or replacement with
disease-tolerant species. Air-drying the stumps kills the fungi. Fire
is ineffective against annosus root disease, Armillaria, and laminated
root rot [56].

Potebniamyces dieback (Phacidium balsamicola) causes small branch
dieback and swelling at the girdling point but does not cause
significant losses. Treatment involves spacing severely infected trees
at precommercial thinning levels. For white-spored rusts (Uredinopsis
spp.), site preparation procedures should avoid encouraging the growth
of alternate hosts. In severe cases, it may be necessary to apply
herbicide to alternate hosts. There is no management practice known for
Virgilla robusta and Abies rust (Pucciniatrum spp.), except to minimize
the number of alternate hosts of Abies rust during site preparation.
Other fungi prevalent in fir stands include Caloscypha fulgens,
Sirococcus blight, and Sirococcus strobilinus [62].

Pacific silver fir is also susceptible to western spruce budworm
(Choristeneura occidentalis), Douglas-fir tussock moth (Orygia
pseudotsugata), and fir-engraver beetle [22,35]. The effects of these
pests can be alleviated by the application of fertilizer, and minimized
by variation of stand structure and by planting pest-tolerant species
[22]. At sites of western spruce budworm infestation, treatment should
decrease the number of vulnerable trees and should increase the number
of young trees by lowering maximum tree sizes. Ambrosia beetles
(Trypodendron lineatum and Gnathotrichus sulcatus) can be captured with
pheromone, multifunnel traps in late June when the beetles are flying.
Harvesting should be planned so that logs are not left on the ground to
be attacked by ambrosia beetles [45]. One of the most devastating pests
to Pacific silver fir is balsam woolly aphid (Adelges piceae) [14,57].
Infested trees appear swollen, with gouty twigs, poor crowns, and little
growth; death occurs within 2 to 3 years [22]. Infested trees have
mottled-red foliage, distinct "crown lean", and appear to die from the
top down. Trees greater than 28 inches (71 cm) in d.b.h. sustain the
most damage among the dominant crown classes [29]. In order to protect
nearby stands, the advance regeneration must be destroyed and the site
should be returned to a seral habitat, such as western hemlock [56].

Pacific silver fir is a secondary host for dwarf mistletoe (Arceuthobium
tsugense and Arceuthobium abietinum) [14]. Dwarf mistletoes cause
growth loss and tree mortality when in association with canker fungi
(Cytospora abietis). The key management practices should be detection,
evaluation, prevention, and suppression. Living infected residues
should be killed before susceptible regeneration reaches 3 feet (0.9 m)
or 10 years of age [22]. Ruth [57] suggests removing the overstory and
burning seedlings and other residue material in seedling infected
stands. Slash burning may be one of the most effective tools to
eliminate dwarf mistletoe. Special site preparation and herbicides may
also be useful tools for treatment [56].

AK CA OR WA BC

Pacific silver fir is grown as an ornamental [51]. It is a major
component of recreational and wilderness areas [14].

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More info for the term: seed

Pacific silver fir has a 2-year reproductive cycle. In May of the first
year, buds are initiated; differentiation follows in July.
Megagametophytes and ovuliferous scales are initiated in mid-July and
mid-August, respectively. Both are dormant by November and remain
dormant until April of the second year, at which time development of the
pollen-cone and seed-cone buds is resumed [63]. Pollination occurs in
May and is well synchronized with female receptivity [14,63].
Fertilization occurs in early July, 4 to 5 weeks after pollination. In
early August, meristems and cotyledons of embryos develop and mature by
the end of the month. Cones change from green to purple at maturity
[6,63]. As cones mature, they disintegrate before the seed can be
dispersed, which occurs in September and October [24,63].

Germination occurs in the spring [14]. Juvenile growth ranges from 4 to
16 inches (10-40 cm) per year [14]. Advance regeneration is quite
sturdy but grows slowly. Terminal growth averages 19.9 (49.7 cm) per
year [14].

More info for the term: seed

Pacific silver fir germinates on exposed mineral soils, but its seed
often travels only a short distance onto the site [56]. Burned soils
have radical temperature fluctuations, which may prevent Pacific silver
fir from establishing on burned sites. One year after the 1978 Hoh fire
in the Olyumpic Mountains, Pacific silver fir seedlings were found at a
great concentration, but they did not appear as healthy as other
seedlings [2]. Slash burning increases the time for Pacific silver fir
to reach 60 percent stocking rate [23].

More info for the terms: root crown, secondary colonizer

Tree without adventitious-bud root crown
Secondary colonizer - off-site seed

More info for the terms: cone, dispersion, frequency, fresh, litter, seed

Pacific silver fir reproduces only from seed [14]. Seed production
begins at 20 to 30 years of age [14]. There are approximately 400 seeds
per cone; percentage of sound seed ranges from 6.3 to 35 percent
[14,24]. Good seed crops are generally produced every 2 to 3 years
[14,59], but intervals between good seed crops may be as long as 6 years
according to some reports [17,25]. Production of seed is poor due to
the high frequency of low pollen production years [14]. Complete crop
failures sometimes occur [59].

Pacific silver fir requires 2 years to complete its reproductive cycle
[63]. It is capable of self-fertilization [14,38]. Wind dispersion of
seed is inefficient because of seed size and cone disintegration [59].
Germination occurs in the spring. Germination can occur on a variety of
substrates such as litter, rotten wood, moss, organic and mineral soils,
and fresh volcanic tephra. Cool, moist sites are optimal for
germination, but full sunlight produces maximum growth [14]. Pacific
silver fir takes 9 years to reach breast height on average sites [14], 5
to 9 years on more favorable sites, and up to 80 years when severely
suppressed [36].

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

1 Northern Pacific Border
2 Cascade Mountains
4 Sierra Mountains

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More info for the terms: climax, dispersion, forest, seed

Obligate Climax Species

Pacific silver fir is a late seral or climax species in most habitats
[41]. In the mountain hemlock zone, Pacific silver fir succeeds species
such as Shasta red fir, subalpine fir, and grand fir [27].

Pacific silver fir is very shade tolerant and has low spatial
requirements [14,15,22,26,71]. Pacific silver fir can survive in the
shade and emerge in stands that are uneven-aged [51]. Due to
ineffecient dispersion of seed by wind, migration is slow [56].

Following disturbance, Douglas-fir and noble fir become established.
Pacific silver fir is the last to invade, sometimes 400 to 500 years
after the disturbance. After extensive forest fires, Pacific silver fir
may not become important among the large trees for 700 to 800 years
[61,69]. Eventually, Douglas-fir and noble fir fail to reproduce [27].
Often, almost all understory species are eliminated by shade, resulting
in an open forest floor [51]. Pacific silver fir is common in mixed
stands and rare in even-aged stands [59].

The currently accepted scientific name for Pacific silver fir is Abies
amabilis (Doug) ex. Loud. Pacific silver fir does not hybridize with
its true fir associates. Some morphological intermediates of Pacific
silver fir and subalpine fir (Abies lasiocarpa) have been reported [42],
but these have proved not to be hybrids [14].

More info for the term: tree

Pacific silver fir is a good choice among tree species for planting in
watersheds and locations with large amounts of mountain snowpack
[22,24,26,41]. It is also well suited for developments such as
campgrounds and trails [28].

The wood of Pacific silver fir is soft, light in weight and color, and
has little odor or resin [14,26]. The wood is weak and has low
durability [26]. The most common uses of Pacific silver fir are light
construction frames, subfloor, construction plywood, sheaths, container
veneer, and pulpwood [14,24,26]. As a "white wood", Pacific silver fir
is a major export to Japan for business construction [24]. It is used
for Christmas trees and decorative greenery [14,24,26].