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National Plant Data Center
PACIFIC SILVER FIR
Abies amabilis (Dougl. ex
Loud.) Dougl.
Plant Symbol = ABAM
Contributed by: Santa Barbara Botanic Garden and
USDA NRCS National Plant Data Center
Susan McDougal, The Flora of Mt. Adams
Uses
Pacific silver fir is used in urban landscaping and
grown commercially for Christmas trees. When used
for landscaping, sufficient space should be allocated
for the relatively large size of mature trees. The soft,
light-weight wood is weak and has low durability. It
has been used for light construction frames,
construction plywood, container veneer, and
pulpwood.
The dense growth of Pacific silver fir provides cover
and protection during the winter for wildlife. Old-
growth stands provide habitat for mountain goat,
northern spotted owl, Vaux’s swift, western red-
backed vole, and the Olympic salamander. Seeds
provide food for birds, rodents, and squirrels, while
the leaves of growing shoots are browsed by elk.
Status
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).
Description
General: Pine Family (Pinaceae). Pacific silver fir is
a U.S. native conifer that ranges from 100 to 230 feet
tall and up to 45 inches in diameter at the base. Like
all true firs, it has erect, cylindrical cones that are
borne near the tips of the uppermost branches.
Secondary branches and twigs are typically in pairs,
with leaves twisted or curved so that they tend to lie
in one plane. Mature cones are 3.5 to 6 inches long
and purple. Mature trees are erect, conical in outline,
with spreading, spray-like branches and a scaly, gray
to whitish bark. Young shoots have a dense, short,
pinkish brown pubescence. Most of the needle-like
leaves range from 0.5 to 1.3 inches long, are bright
green, somewhat flattened, and have notched tips.
Distribution: For current distribution, please consult
the Plant Profile page for this species on the
PLANTS Web site.
Adaptation
Native to the Pacific Northwest, Pacific silver fir
ranges from southern Alaska to northern California.
Well developed stands are primarily found at
elevations from 1,000 to 7,000 feet on the coastal
slopes of the Cascades. However, in the northern
part of its range, stands occur well below 1,000 feet.
Pacific silver fir usually occurs in uniform stands or
associated with western hemlock (Tsuga
heterophylla). The geographic range is characterized
by a maritime to submaritime climate, with an annual
precipitation between 40 to 260 inches per year, and
average summer temperatures between 57 to 59
degrees F. Plants have a mild frost tolerance and a
low tolerance for frozen soil conditions. Soils are
usually very moist, somewhat acidic (pH 5), and rich
in magnesium and calcium. A thin bark and highly
flammable foliage contribute to low levels of
resistance to fire.
Establishment
Pacific silver firs reproduce only from seed. Both
pollination and seed dispersal are effected by wind.
Plants are capable of self-fertilization and produce
mature cones and seeds two years after pollination.
Cones disintegrate while on the tree and seeds are
http://plants.usda.gov/java/largeImage?imageID=abam_008_avp.tif
either dispersed by wind or small mammals. Cool
moist sites are optimal for germination, but full
sunlight produces maximum growth. Germination
can occur on a variety of substrates, including litter,
rotten wood, moss, and organic and mineral soils.
Management
Management for most fungal diseases involves
thinning at least 25 feet from dead trees and
minimizing wounding during logging or trimming.
Treating remaining stumps with fungicide or stump
removal after logging is useful in preventing further
contamination. In some cases, removal of infected
trees and trunks should be practiced as soon as
disease is diagnosed. Air drying large stumps often
reduces chances of further infection.
Pests and Potential Problems
Pacific silver firs are susceptible to several fungal
diseased, including Annosus root disease
(Heterobasidion annosum). Infected trees may show
retarded leader growth, sparse and chlorotic foliage,
stem decay, and abortive cones. The most reliable
way to detect this disease is by the presence of
fruiting bodies in the duff layer at the root collar on
the outer bark. Trees become infected by rood
contact or by airborne spores falling onto woonds.
Other fungal diseases include Indian paint fungus
(Echinodontium tinctorium) and laminated root rot
(Phellinus weirii). Both can infect stands of trees and
result in patches of damaged or dead trees.
Trees weakened by disease or poor growing
conditions may become infested with fir-engraver
beetle (Scolylus ventralis), silver fir beetle
(Pseudohylesinus sericeus), or fir root bark beetle
(Pseudohylesinus granulatus). In large numbers,
these beetles may kill entire trees before any
symptoms are observed. Pacific silver firs are also
susceptible to Western spruce budworm
(Choristeneura occidentalis), Douglas fir tussock
moth (Orygia pseudotsugata) infestation. Applying
fertilized and varying the age and density of stands
reduces the infestation. Balsam wooly aphids
(Adelges piceae) are an extremely devastating pest to
this species. Infected trees appear swollen with little
growth and usually die from the top down within 2 to
3 years. To prevent further infestation, most trees
need to be removed and the site rplanted with such
species as western hemlock.
Seeds and Plant Production
Cone production may begin at an age of 20 to 30
years. Each cone can produce up to 400 seeds, but
the percentage of viable seed ranges from 6.3 to 35
percent. Preferred methods of cone collecting
include extension poles with appropriate pruners.
Cones should be collected between mid and late
August or just prior to disintegration. They should be
stored in well-ventilated bags or sacks at
temperatures between 70 and 80 degrees until the
cones have disintegrated. Seeds can be extracted
mechanically by using screens and then cold-
stratified under dry conditions at temperatures
between 10 and 30 degrees F for 4 to 6 months.
Germination is best accomplished by placing them in
a moist, well-aerated soil mix at temperatures
between 35 and 40 degrees F. Light enhances
germination and development of seedlings. Plant
can be grown either individually in containers or in
flats prior to transplantation. Under field conditions,
seed should be sown in the spring at a density of 62.5
to 125 per acre and approximately 0.25 inches deep.
During the first few years, growth ranges from 4 to
16 inches annually. Fertilizer combined with
thinning enhances growth.
Cultivars, Improved, and Selected Materials (and
area of origin)
Contact your local Natural Resources Conservation
Service (formerly Soil Conservation Service) office
for more information. Look in the phone book under
”United States Government.” The Natural Resources
Conservation Service will be listed under the
subheading “Department of Agriculture.”
Cultivars include a slow-growing, broadly ovoid
form, ‘Compacta’ and a low-growing, spreading form
with horizontal branches, ‘Spreading Star.’ Retail
nurseries in the Pacific Northwest that stock native
shrubs and trees may carry the cultivars.
References
Arno, S. & R. Hammerly. 1977. Northwest trees. The
Mountaineers, Seattle, Washington. 222 p.
Dickman, A. & S. Cook. 1989. Fire and fungus in a
mountain hemlock forest. Canadian Journal of Botany
67:2005-2016.
Filip, G. & C. Schmitt. 1990. Rx for Abies:
Silvicultural options for diseased firs in Oregon and
Washington. USDA Forest Service, Pacific
Northwest Research Station, Gen. Tech. Report 252.
34 p.
Klinka, K., V. Krajina, A. Ceska, & A. Scagel. 1989.
Indicator plants of coastal British Columbia.
University of British Columbia Press, Vancouver.
288 p.
Krajina, V., K. Klinka, & J. Worrall. 1982.
Distribution and ecological characteristis of trees and
shrubs of British Columbia. University of British
Columbia, Vancouver. 131 p.
Oliver, C. & R. Kenady (eds.). 1982. Proceedings of
the biology and management of true fir in the Pacific
Northwest. University of Washington, College of
Forest Resources, Contribution No. 45, Seattle.
USDA NRCS. 2007. The PLANTS website.http://plants.usda.gov. Accessed 070117. National
Plant Data Center, Baton Rouge, Louisiana.
Prepared By
Dieter Wilken, Santa Barbara Botanic Garden, Santa
Barbara, California
Species Coordinator
Dieter Wilken, Santa Barbara Botanic Garden, Santa
Barbara, California
Edited: 070117 jsp
For more information about this and other plants, please contact
your local NRCS field office or Conservation District, and visit the
PLANTS Web site or the Plant Materials
Program Web site
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