White Fir

Foodplant / gall
mycelium of Melampsorella caryophyllacearum causes gall of pale yellow, shorter, thicker, growing vertically upwards stem of Abies lowiana

Abies concolor is a western catchall species for firs with green seed cones and with glaucous adaxial leaf surfaces. Many of these populations have long been isolated geographically and genetically. A geographic cluster of populations in Utah has shorter leaves and slightly different terpene patterns than a similar cluster of populations in Colorado and northern New Mexico (J.W. Wright et al. 1971; E.Zavarin et al. 1975). Another large geographic cluster, in southern New Mexico and Arizona, seems to be strongly linked chemically to Colorado populations (E.Zavarin et al. 1975) and morphologically to southern California populations (J.L. Hamrick and W.J. Libby 1972). Northern California populations with pubescent twigs and notched leaves are unique, as are the Baja California populations with very short, thick leaves and about 18 adaxial stomatal rows. In Los Padres National Forest of coastal southern California and in the Cascades of northern California, apparent introgression with A . lowiana (E.Zavarin et al. 1975; J.L. Hamrick and W.J. Libby 1972) has occurred. Many consider A . lowiana (given specific rank in this treatment) as a synonym of A . concolor or place it in an infraspecific rank under that species.

Trees to 40m; trunk to 0.9m diam.; crown spirelike. Bark gray, thin, smooth, with age thickening (to 18cm) and breaking into deep longitudinal furrows, often revealing yellowish inner periderm, appearing "corky." Branches diverging from trunk at right angles, the lower often spreading and drooping in age; twigs mostly opposite, glabrous or with yellowish pubescence. Buds exposed, either yellowish and nearly conic (when large) or brownish and nearly globose (when small), resinous, apex rounded to pointed; basal scales equilaterally triangular, glabrous, not resinous, margins entire, apex sharp-pointed. Leaves 1.5--6cm ´ 2--3mm, mostly 2-ranked, flexible, proximal portion ±straight; cross section flat, sometimes slightly grooved adaxially; odor pungent, frequently camphorlike; abaxial surface glaucous, with 4--7 stomatal rows on each side of midrib; adaxial surface grayish green, glaucous, with (7--)12(--18) stomatal rows at midleaf, these usually fewer toward leaf apex; apex usually rounded, sometimes acute or notched; resin canals small, near margins and abaxial epidermal layer. Pollen cones at pollination ± red, purple, or ± green. Seed cones cylindric, 7--12 ´ 3--4.5cm, olive-green, sessile, apex round; scales ca. 2.5--3 ´ 3--3.5cm, pubescent; bracts included. Seeds 8--12 × 3mm, body tan; wing about twice as long as body, tan with rosy tinge; cotyledons 5--7. 2 n =24.

Coniferous forests; 1700--3400m; Ariz., Calif., Colo., Idaho, Nev., N.Mex., Oreg., Utah; Mexico in Baja California, Sonora.

Picea concolor Gordon & Glendinning, Pinetum, 155. 1858

The firs are large, stately conifers with single trunks, whorled branches and very symmetrical cone shaped habits. Firs can be distinguished from other conifers by the combination of flat needles which are whitish beneath, and upright cones which stay on the tree and disintegrate after the seeds have been shed, leaving behind a single spikelike axis for a while. White fir has yellowish green first year branchlets, needles that are bluish green above, and rough, pale gray bark. The needles are about 2 in (5 cm) long with a pair of whitish bands on the underside. They appear to grow in two ranks on the branchlets, resulting in flattened sprays of foliage. The upright cones are cylindrical, about 5 in (13 cm) long and purplish green. White fir can get over 100 ft (30.5 m) tall and its conical spirelike crown becomes more columnar with age. Young trees are usually branched to the base, but large specimens are often devoid of branches for a third of their height. In cultivation, expect white firs to get 40-60 ft (12-18 m) tall. This is a very popular ornamental conifer and quite a few cultivars of varying habits and sizes have been named.

White fir tolerates a wide range of soil types, preferring those slightly on the acidic side. These are long lived, but still fast growing trees, reported to grow 50-60 ft (15-18 m) in the first 30-60 years; after that the growth rate slows dramatically. Don't prune firs except to remove the occasional double leader; they do not fill in with new branches after pruning. Light: White fir can tolerate a little light shade, but it does best in full sun. Moisture: Firs do best on north-facing slopes and should be protected from drying winds. White fir requires a moist soil and a moderately humid climate. They do best where winters are long. with moderate to heavy snowfall. White fir cannot be grown in dry climates. Hardiness: USDA Zones 4 - 7. Firs cannot be grown in hot climates. Propagation: The firs are difficult to start from cuttings. White fir is propagated from seed, which should be stratified under cool, moist conditions for several weeks. The cultivars are usually grafted onto seedling rootstock. White firs do not begin producing cones and seeds until about 40 years of age. On average, they have abundant seed crops every five years.

White fir is a popular ornamental in Canada and the northern U.S. In general, firs cannot tolerate drought, heat and air pollution, but white fir does a little better in each respect than most, and is the best fir for most landscape applications. They are excellent specimen trees for moderate to large landscapes. The fastigiate, weeping and dwarf cultivars are interesting novelties for smaller landscapes. 'Compacta' is especially desirable. The wood of white fir is very soft and coarse grained, and used mainly for paper pulp and shipping crates. Lacking a distinctive odor, the wood was formerly made into food containers (especially for butter) prior to the widespread use of plastics.

More info for the terms: density, duff, forest, fuel, fuel loading, litter, shrub, tree

The effects of fire on white fir vary with size and age of tree, stand density, fuel loading and fire conditions.

Prescribed low-intensity summer surface fires in mixed conifer forests of Crater Lake National Park, Oregon, resulted in high mortality of small white firs [303]. Similarly, prescribed, low-intensity fall surface fires in a giant sequoia-mixed conifer forest in Kings Canyon National Park, California, resulted in mortality of 91% of trees less than 6 inches (15 cm) dbh, 39% of trees 6-12 inches (15-30 cm) dbh, and 5% of trees larger than 12 inches dbh [168].

Greater reduction in density is obtained in stands with higher prefire densities. In white fir stands with dense vegetation, consisting of both young stands of pure white fir and open stands of white fir with a shrub understory, fires burned at high intensity and killed most trees in the area studied in the Marble Mountains of California. In lower density forest stands of white fir with old-growth characteristics, fires were of low intensity and burned down rotten logs and standing snags with very little damage to the canopy trees [305]. Prescribed fires resulted in an increase in the density of giant sequoia at the expense of white fir [164,165,169].

Greater mortality of mature trees could be expected in stands with a deep litter layer, since smoldering of the duff for long periods after the fire has passed kills the moderately shallow roots of white fir [4].

More info for the terms: basal area, cover, crown fire, density, fire frequency, fire severity, fire suppression, forest, frequency, fuel, fuel moisture, prescribed fire, seed, severity, shrub, shrubs, stand-replacing fire, tree, wildfire, woodland

The response of white fir to fire is inconsistent and may vary with fire
frequency and severity, associated vegetation in the postfire community, location of seed
trees, postfire insect and disease effects, and postfire browsing by animals.
Mean annual post-fire mortality of 17.8% in white fir was related primarily to
fire-caused crown scorch and possibly fine root mortality in Sequoia National
Park [233]. White fir is considered more fire resistant than its associated
species at high elevations, but less resistant than associated species at low
elevations [178,219].
Tree associates Douglas-fir and ponderosa pine are favored by more
frequent fires [345]. If the time between fires is long enough, white fir
seedlings can germinate
and establish under brush cover and thus establish crown
dominance over time [65,178,211].

In the mixed conifer zone of the Sierra Nevada, white
fir seedling are often abundant under montane chaparral shrubs that form brushfields
after high severity crown fires. Conard and Radosevich [65] found
white fir reproducing abundantly on shrub-dominated sites, with a combined
seedling and sapling density ranging from 445 to 4,453 per acre (1100-11,000/ha)
where crown fires had occurred 38 to 62 years earlier. Densities of both
snowbrush ceanothus and manzanita were higher on burned than on unburned and on
logged than on unlogged plots [329]. Fire severity can be an
important determinant of shrub response in white fir stands. Preharvest burning
in a 70-year-old white fir stand in northeastern California resulted in
410,000 snowbrush ceanothus seedlings/ha in moderate-consumption
burns, and 94% seed mortality in more severe burns - killing seeds to a depth
of 10 cm in the soil [330,331].

Minnich [218] studied conifer reproduction on
burned areas in mixed conifer forests in the San Gabriel and San Bernardino
mountains of southern California. He found that seeds originating from outside
the burned area were responsible for abundant white fir production on burns
older than 10 years, but that reproduction was scant on burns less than 5 years
old. Similarly, no white fir seedlings established within 5 years of a crown fire
in the Sierra Nevada, even though several mature trees survived the fire
and thus provided a seed source [65]. Another Sierra Nevada study found
negligible white fir reproduction 17 years following a stand-replacing
fire, even though a seed source was readily available [51]. Less than 1 year following
underburning in a giant
sequoia grove, white fir seedling establishment in June was abundant, with 39%
survival in October [6].

Most mortality in white fir after the 1st year postfire in mixed conifer
in southern Oregon was associated with bark beetles [303].

Near the Plumas National Forest, prescribed fire in a mixed-conifer-California
black oak forest with a white fir component successfully reduced
fuel load. When a wildfire burned through the site previously burned under
prescription, fire severity and fire suppression costs were less compared to
adjacent land where fire had been excluded [221]. For further information
on this study, see the
Research Paper by Moghaddas [221].

Fall prescribed fire on the Tharp Creek Watershed of Sequoia National Park
produced 16.4% and 17.8% mean annual mortality for all size classes of white fir
on 2 white fir-mixed conifer sites that were monitored for 5 years after fire.
Mortality was concentrated in the subcanopy.
Probability of mortality increased with percentage of crown killed and decreased
with DBH. Basal area changes were also monitored before and after the fire.
Compared to the unburned control, mean percent change in white fir basal area decreased an average of 0.10% on 1 site and
increased 0.61% on the other. From 1989 to 1994 (includes 1 year of prefire data),
percent change in white fir basal area was reduced an average of 4.97% and 6.03%
on the 2 burned sites compared to the control site [233]. For more information, see
a summary of the study in Fire Case Studies.

For further information on white fir's response to fire, see these Research Project Summaries:

• 
  
  Plant response to prescribed burning with varying season, weather, and fuel moisture in mixed-conifer forests of California




• 
  
  Response of vegetation to prescribed burning in a Jeffrey pine-California black oak woodland
  and a deergrass meadow at Cuyamaca State Park, California

white fir

California white fir

Rocky Mountain white fir

More info for the terms: cover, forest, hibernation, shrubs, tree

White fir's evergreen foliage provides good hiding cover year-round and is usually continuous from the ground upward on trees less than 8 to 10 inches (20-25 cm) dbh [148]. White fir stands of this nature provide excellent hiding cover for large wildlife species such as deer, elk, and black bear [141,187]. If enough shrubs are present in the understory to provide adequate hiding cover, mature white fir forests are used by deer during fawning and by elk during calving [149,174].

In mixed conifer forests of the Sierra Nevada, cavity-nesting birds prefer white fir snags over the snags of associated trees. Cavity nesters using white fir snags include the American kestrel, mountain chickadee, brown creeper, mountain bluebird, house wren, tree swallow, northern flicker, and several nuthatch, sapsucker and woodpecker species [252]. Other forest songbirds nest within white fir foliage. Hollowed trunks of older trees are used by several species of mammals such as black bears, for hibernation; American martens, for dens and rest sites; and bushy-tailed woodrats, flying squirrels and other small mammals for cover [185,240]. Most bear dens in Yosemite National Park are found in the hollowed trunks of white fir [202].

More info for the terms: association, tree

White fir is a large, native, coniferous tree. Mature white fir trees in the central Sierra Nevada are 140 to 180 feet (43-55 m) tall, and 40 to 80 inches (1-2 m) dbh, but may grow larger [104,186]. Rocky mountain white fir rarely exceeds 125 feet (38 m) tall or 3 feet (0.9 m) in diameter [104]. Bark on young trunks is smooth, gray and blistered with resin vesicles, becoming thick, hard and deeply furrowed into scaly ridges with age [71,162].

The crown of young trees is symmetrical and sharp-pointed, becoming irregular and rounded at the summit [162]. California white fir has a narrow, cylindrical, almost spire-like crown [185,186]. Rocky mountain white fir tends to have a broader crown [185]. White fir branches are short and stout, with leaves 1.2 to 2.8 inches (3-7 cm) long and generally curved upward. Branches are arranged in whorls of 4 or 5, which are repeatedly branched in one plane to form flat, horizontal sprays. Buds are blunt and resinous [71]. In Arizona white fir stands, braches reach nearly to the ground if the trees are widely spaced, and in more dense stands, half or more of the trunk is often bare [162].

The rooting habit of white fir is usually fairly shallow, but appears to be adaptable to local conditions: deep and intensive where soil conditions permit, to shallow and widespread where rocks or seasonal water tables limit effective soil depth. There is no strong tendency to maintain a single deep taproot although rapid taproot development is critical for survival of new germinants in a dry summer climate. White fir is susceptible to wind throw following partial cutting. Root diseases may contribute to lack of wind firmness. Root grafting between firs is common and is a factor in the spread of root rots [178]. Effects of mycorrhizal associations have been explored and appear to be important in white fir, especially for establishment and early growth on poor sites. It appears that bare mineral soils promote the association [22,178].

White fir is thought to be a slow growing species [157,178,219]. It can survive for exceptionally long periods as a suppressed tree and still respond to release by increasing growth dramatically. White fir may reach ages of 300-400 years. Old growth characteristics in Southwest are given by [295]. Information on productivity of white fir is available [178,201,263].

The varietal differences in California and Rocky Mountain white fir are based on differences in morphological and chemical characteristics, such as needle tip shape and stomatal arrangement [40,133] and terpene content [124,178]. 

More info for the terms: fire exclusion, fire regime, fire tolerant, forest, frequency, fuel, fuel continuity, fuel moisture, habitat type, mesic, seed, severity, shrubs, stand-replacement fire, stand-replacement fire regime, succession, tree, understory fire, understory fire regime, woodland

FIRE REGIMES: White fir occurs in a variety of forest and habitat types that evolved with a variety of FIRE REGIMES. Thin-barked and resin blistered, with drooping lower branches, young white fir is highly susceptible to fire, and mature trees are only moderately fire tolerant. White fir is an aggressive, shade-tolerant species that will seed into the understory of low-elevation ponderosa or Jeffrey pine stands or into mixtures of ponderosa pine, Douglas-fir, quaking aspen, and southwestern white pine [185]. On these sites, its numbers were previously controlled by frequent surface fires. With fewer fires in the last century, it is becoming a major stand component at elevations and on sites where historically it was minor [178]. At mid-elevations in the mixed conifer and white fir zones, fires may have burned in a pattern of different severities, including patches where most of the moderately susceptible trees such as white fir, survived [25], and patches where white fir stands were completely destroyed [201]. This type of fire regime creates a forest mosaic of stands with varied structures, species compositions, and seral stages. White fir is also a component of forest communities that evolved with less frequent, stand-replacing fires. The following discussion provides examples from white fir communities that evolved with mixed, understory, and stand-replacement fire regimes.

The primary range of white fir is in the mid-elevation, mixed conifer and white fir zones in California and the central and southern Rocky Mountains. These forest types may be characterized by a mixed fire regime, with fires of variable frequency and severity [25], with some sites experiencing frequent surface fires [7], and others experiencing infrequent crown fires. Mean fire intervals are generally intermediate to intervals in understory and stand replacement regimes, ranging between 30 and 100 years [25]. Mean fire intervals in Sierra Nevada mixed conifer forests are estimated to range between 5 and 30 years, and varied in response to ignition source, fuel accumulations, fuel moisture and burning conditions [333]. Any given location within a mixed fire regime could experience some stand-replacement fires and some nonlethal fires along with a number of fires that burned at mixed severities, creating mosaic patterns of stand structure and fuels [25,215,305]. Low severity fires thin understory regenerating trees, while more severe crown fires may knock succession back to herbs and shrubs. Thus, past burn mosaics tended to increase the probability that subsequent fires would also burn in a mixed pattern. Complex mountain topography also contributed to variable fuels and burning conditions that favored nonuniform fire behavior [25]. After decades of fire exclusion, much of the landscape mosaic has aged and advanced successionally, and patches of late successional forests with large accumulations of dead and living fuels have coalesced, increasing likelihood of fires of unusual size and severity [25,54,169,209,286,287,288,316]. This shift toward landscape homogeneity may adversely affect biodiversity, and may also be perpetuated as the probability of large, high-severity fires increases with continued fire suppression [339]. Much of the living fuels in these forests are small white firs and other shade tolerant species, filling in the understories with dense thickets and increasing fuel continuity and fire ladders of resinous foliage, often in cylindrical crowns that may lead to crown fires when they do burn [178,186,247,288]. Fuel loadings in this type may vary widely due to stand history and site productivity [25,331].

There is evidence that a mixed regime may have been important for perpetuation of giant sequoia groves in the Sierra Nevada [25,296]. Giant sequoia groves burned every 2-10 years for the last 3000 years and have not burned in 100-130 years [289,290,296]. The more mesic, mid-elevation, mixed conifer forests of California formerly experienced low to moderate severity wildfires every15 to 30 years [288,333]. Other areas that may have had mixed fire regimes include the Marble Mountains of northern California [305]; the mixed conifer zone in the montane forests of the Madrean borderlands; the Animas Mountains of southwest New Mexico [297]; mixed conifer forests in the Jemez Mountains, New Mexico [308]; the white fir/Rocky Mountain maple habitat type in Arizona and New Mexico [232,295]; the high elevation, white fir/forest fleabane habitat type [295]; the lowest elevations of the subalpine forest in New Mexico [86,157,247]; the mixed conifer zone of the Sandia Mountains, New Mexico [36]; and the white fir zone in the central Siskiyou Mountains, Oregon [3].

White fir is also a component of drier ponderosa and Jeffrey pine habitat types that evolved with an understory fire regime. An understory fire regime is characterized by relatively frequent, low severity fires that result in open, uneven-aged stands consisting primarily of the more fire tolerant species. White fir was not a major component of these stands under this regime, and existed as scattered individuals or small groups that managed to survive to a fire resistant age. Open ponderosa pine, larch and Douglas-fir forests at lower elevations in the west have been extensively harvested and protected from fire resulting in a compositional shift to an unnaturally dense understory of Douglas-fir, grand fir white fir, or incense-cedar [27,185,234]. Areas where this fire regime was important include the ponderosa pine and mixed conifer forests of southern Arizona and New Mexico [33,35,68,115,297]; the Sacramento and White mountains of New Mexico [224]; and ponderosa pine stands in central Oregon [253,298]. Because of changes in fuels during the last century, these areas may now experience crown fires when they do burn, with high tree mortality [5].

White fir may also be a component in ecosystems with a stand-replacement fire regime such as western subalpine forests and Douglas-fir/western hemlock forests [25]. The more arid Jeffrey pine forests on the Mojave Desert side of the mountains in southern California may also have a stand-replacement fire regime due to the slow build up of fuels in the arid environment [288]. Evidence of a stand-replacement fire regime in a white fir-Jeffrey pine forest type in the Lake Tahoe Basin is presented by Russell and others [264]. Similarly, the subalpine forests are limited by cold and are also slow growing so fires are naturally infrequent and when they do burn it is usually a stand replacing fire in severe weather [5,288].

The following table provides some fire regime intervals for ecosystems in which white fir occurs. Find further 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".

Community or Ecosystem Dominant Species Fire Return Interval Range (years) silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii > 200 California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [59] curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1000 [28,272] mountain-mahogany-Gambel oak scrub C. l.-Quercus gambelii western juniper Juniperus occidentalis 20-70  Rocky Mountain juniper J. scopulorum Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to > 200  blue spruce* P. pungens 35-200  pinyon-juniper Pinus-Juniperus spp. 59] Rocky Mountain lodgepole pine* P. contorta var. latifolia 25-300+ [24,260] Sierra lodgepole pine* P. c. var. murrayana 35-200  Colorado pinyon P. edulis 10-49 Jeffrey pine P. jeffreyi 5-30 western white pine* P. monticola 50-200  Pacific ponderosa pine* P. ponderosa var. ponderosa 1-47  Rocky Mountain ponderosa pine* P. p. var. scopulorum 2-10 Arizona pine P. p. var. arizonica 2-10 [59] quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [59,125,213] mountain grasslands Pseudoroegneria spicata 3-40 (10**) [24] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [59] coastal Douglas-fir* P. m. var. menziesii 40-240 [59,229,259] California mixed evergreen P. m. var. m.-Lithocarpus densiflorus-Arbutus m. California oakwoods Quercus spp. oak-juniper woodland (Southwest) Quercus-Juniperus spp. canyon live oak Q. chrysolepis California black oak Q. kelloggii 5-30 western redcedar-western hemlock Thuja plicata-Tsuga heterophylla > 200 mountain hemlock* T. mertensiana 35 to > 200  elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. 59] *fire return interval varies widely; trends in variation are noted in the species review
**(mean)

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More info for the term: phanerophyte

RAUNKIAER [254] LIFE FORM:
Phanerophyte (undisturbed)

More info for the terms: climax, fern, mesic, radicle, soil temperature regimes, xeric

Because of its wide distribution, white fir is subjected to very different climates, soils, animals, plant associates and other environmental factors from place to place [186].

Rocky Mountain white fir grows on high mountains with precipitation ranging from 20 to 35 inches (510-890 mm). California white fir grows in cold, high elevations and warm-to-hot low elevations with precipitation ranging from 35 to 75 inches (890-1900 mm), but grows best in the southern Cascades and western Sierra Nevada, where precipitation is between 39 and 49 inches (990-1240 mm) [178]. Within the mixed conifer forests of the Sierra Nevada, white fir tends to occupy the more mesic sites, such as northern exposures, at lower elevations, and the more xeric sites at upper elevations [111,263]. In Utah, white fir typically occupies cool and dry northern exposures [201,345]. In the Southwest, white fir occupies numerous topographical settings, and local conditions can vary from cold and moist to warm and dry [83]. Winter snowpack provides the majority of the moisture at high elevations, with fall and early spring rains providing most of the moisture at lower elevations [178]. The upper latitudinal limit of white fir may coincide with a mean maximum January temperature of about 30 to 32 degrees Fahrenheit (-1 to 0 °C) [201]. White fir is sensitive to both frost damage and, occasionally sun scald [178]. White fir is also moderately susceptible to ozone damage [157]. White fir is less tolerant of shade than associated true firs (except red fir), is slightly more tolerant than Douglas-fir, and is much more tolerant than pines or oaks [157,178,219].

California white fir occurs in a wide elevational range, as low as 3,000 feet (900 m) in the North Coast Ranges to over 10,000 feet (3000 m) in the San Bernardino Mountains and the Sierra San Pedro Mártir of Baja, California [186]. Pure white fir forests are common in Oregon and California and they occupy a narrow elevational band from about 4,600 to 5,250 feet (1400-1600 m) in the southern Cascades and from 5,400 to 5,900 feet (1650-1800 m) in the Siskiyou Mountains of northwestern California [111]. In the Sierra Nevada, white fir is a major component of mixed conifer forests occurring between 4,100 to 7,200 feet (1250-2200 m) [263]. Rocky Mountain white fir is found most frequently at elevations ranging from 6,900 to 8,900 feet (2100-2700 m) [178]. In the mountains of southern Arizona, it occupies the highest elevations [188]. Generalized elevational and precipitation ranges are as follows, by state:

State Elevation Range Precipitation Range References California 3,900-9,800 feet (1200-3000 m) [178] Oregon 2,000-6,600 feet (600-2000 m) 14-45 inches (350-1150 mm) [64,146] Utah 5,000-9,200 feet (1500-2800 m) [201,345] Colorado 7,900-10,200 feet (2400-3100 m) [83] Arizona 5,500-9,000 feet (1700-2750 m) [162] New Mexico 6,400-10,200 feet (1950-3100 m) [295]

White fir grows on a variety of slightly to strongly acid soils from almost every type of parent material [14,104,111,178,186,201]. It is generally tolerant of a wide range of soil conditions, nutrient availability and pH values. Growth and development are best on moderately deep and well-drained sandy-loam to clay-loam soils, regardless of parent material. California white fir is moderately sensitive to excess soil moisture [178]. White fir is usually found on frigid soil temperature regimes or the warmest of the cryic regimes [247,295]. In the arid Organ Mountains of southern New Mexico white fir occurs as a topo-edaphic climax on the cool upper eastern slopes [84].

White fir grows from canyon bottoms and ravines up to ridgetops on gentle, moderate, and steep slopes of all aspects. It develops best on gentle slopes and level ground [178]. In the Rocky Mountains, white fir, along with blue spruce and Douglas-fir, often replaces the dominant deciduous species near middle elevation streams passing through sheltered valleys or canyons [245].

Botanical associates of white fir that may affect its growth include snowbrush ceanothus, which contains allelopathic chemicals in its foliage that suppress radicle growth of white fir [66,178]. Mycorrhizal associations are thought to protect white fir roots from allelopathic chemicals produced by bracken fern [178].

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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):

More info for the term: cover

SAF COVER TYPES [92]:




205 Mountain hemlock

206 Engelmann spruce-subalpine fir

207 Red fir

209 Bristlecone pine

210 Interior Douglas-fir

211 White fir

213 Grand fir

216 Blue spruce

217 Aspen

218 Lodgepole pine

219 Limber pine

220 Rocky Mountain juniper

222 Black cottonwood-willow

224 Western hemlock

227 Western redcedar-western hemlock

228 Western redcedar

229 Pacific Douglas-fir

230 Douglas-fir-western hemlock

231 Port-Orford-cedar

234 Douglas-fir-tanoak-Pacific madrone

235 Cottonwood-willow

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

243 Sierra Nevada mixed conifer

244 Pacific ponderosa pine-Douglas-fir

245 Pacific ponderosa pine

246 California black oak

247 Jeffrey pine

249 Canyon live oak

256 California mixed subalpine

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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):

More info for the term: shrub

ECOSYSTEMS [117]:




FRES20 Douglas-fir

FRES21 Ponderosa pine

FRES23 Fir-spruce

FRES26 Lodgepole pine

FRES28 Western hardwoods

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

FRES37 Mountain meadows

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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 terms: forest, shrub, woodland

KUCHLER [176] PLANT ASSOCIATIONS:




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

K007 Red fir forest

K008 Lodgepole pine-subalpine forest

K010 Ponderosa shrub forest

K012 Douglas-fir forest

K018 Pine-Douglas-fir forest

K019 Arizona pine forest

K020 Spruce-fir-Douglas-fir forest

K021 Southwestern spruce-fir forest

K022 Great Basin pine forest

K023 Juniper-pinyon woodland

K024 Juniper steppe woodland

K029 California mixed evergreen forest

K030 California oakwoods

K031 Oak-juniper woodland

K032 Transition between K031 and K037

K034 Montane chaparral

K037 Mountain-mahogany-oak scrub

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, forb, shrubland, woodland

SRM (RANGELAND) COVER TYPES [275]:




107 Western juniper/big sagebrush/bluebunch wheatgrass

109 Ponderosa pine shrubland

110 Ponderosa pine-grassland

203 Riparian woodland

209 Montane shrubland

210 Bitterbrush

216 Montane meadows

235 Cottonwood-willow

409 Tall forb

411 Aspen woodland

412 Juniper-pinyon woodland

413 Gambel oak

415 Curlleaf mountain-mahogany

418 Bigtooth maple

419 Bittercherry

420 Snowbrush

421 Chokecherry-serviceberry-rose

422 Riparian

504 Juniper-pinyon pine woodland

More info for the terms: fuel, lichen

White fir seedlings, saplings and poles are thin-barked and resin blistered and are highly susceptible to fire damage and kill [178]. Additionally, young trees have low-growing branches that can easily ignite from burning undergrowth, providing a fuel ladder into the crown. Consequently, young white fir are usually killed by even low-intensity, surface fires [29,168,303]. As trees mature and bark thickens, and some self-pruning of lower branches occurs, they become more resistant to fire [345]. However, the tendency to retain some low branches, the moderately shallow roots, and heavy lichen growth on the branches of white fir make it only moderately fire resistant [55]. In larger trees, mortality results from crown scorch, girdled stems from cambial heating, or damage to moderately shallow roots from soil heating [303,328].

More info for the terms: association, codominant, cover, forest, shrub, tree

Stands dominated by white fir seldom produce enough forage for domestic livestock grazing except on harvested or open forest sites, or where grasses and sedges dominate the understory [81]. These forests do, however, provide abundant browse and cover for large and small wildlife species [83,295]. Deer, elk, and bear often use white fir habitats as either summer or winter range [2,189]. Mule and black-tailed deer generally eat small amounts of white fir during the spring, fall, and winter, and sometimes larger amounts during the summer [152,177,189]. Mule deer are especially fond of succulent, new white fir growth in the spring [114,178,185]. Spring browsing of white fir by deer can be particularly heavy when small white firs are the only green food available; all of the current or previous year's growth may be consumed [119]. Porcupines enjoy the bark of white fir, and may destroy saplings in their enthusiasm [138,185,201]. Rodents feed on the cambial tissue of white fir in preference to that of Douglas-fir. During the winter, mice feed on the leaders of small white firs near snow level. In the spring, they feed on seedlings, sometimes destroying a large proportion of the current year's seedlings [138,201]. Pocket gophers also feed on white fir seedlings in the winter and spring [157,178]. White fir needles are an important part of the diet of blue grouse [127,197]. White fir seeds are eaten by several species of small mammals and birds including grouse [183,323], chipmunks and mice [324], flying squirrels [346], chickadees, crossbills, and Clark's nutcracker [127,197]. In the southern Cascades and Sierra Nevada, the Douglas squirrel cuts and caches white fir cones during late summer and fall, before the cones are fully mature [106,114,185]. Hollow logs and snags of white fir can be important to various birds and animals for foraging in the interior wood [240].

There are about 33 species of mammals commonly present in the white fir forest type in California, and of these 7 are generally associated with mature forests [178]. Hollowed-out trunks of old white fir trees, dead or alive, are denning sites for mammals ranging form weasels to porcupines to black bears [186]. In one study, abundance of white fir had a strong positive association with California mountain beaver habitat use [42]. About 123 species of birds are found in the white fir type of California and southern Oregon, about 50 of which are associated primarily with mature forests, and many of which use mature white fir trees and snags for foraging, roosting, nesting and/or breeding [155,178,212,228,318]. These include bald eagles [78,293], northern spotted owls [107,182,304], California spotted owls [44,61,128,319,320], flammulated owls [321], brown creepers and red-breasted nuthatches [1]. In Oregon, mature white fir forests provide nesting and feeding habitat for important bird species, such as the goshawk, pileated woodpecker, white-headed woodpecker, and, when near lakes or streams, osprey and bald eagle [149]. Reptiles in white fir forests are represented by 17 species, mostly at lower elevations, 8 of which are associated with mature forests [178].

In the southwest, desert bighorn sheep and white-tailed deer occasionally browse white fir [183,277]. In the Rocky Mountains, red squirrels cache white fir cones during late summer and fall before the cones are fully mature [106,114,185]. Some white fir habitat types in the Southwest and Utah provide habitat for black bears and cougars and have high cover value for wildlife [190,295]. In riparian woodlands in the Southwest, white fir is often a codominant species with hardwoods such as maples. These woodlands tend to be small in area, but provide unique and critical habitat for many species of wildlife such as the Arizona gray squirrel, river otter, zone-tailed hawk, common black hawk, American dipper, summer tanager, bullock oriole, yellow warbler, Arizona alligator lizard, Sonoran mud turtle, and canyon tree frog [12,101,295]. At the southern end of its range in the Madrean region, white fir occurs in "island" habitats at the uppermost elevations of isolated mountain ranges, providing small areas of geographically unique habitat for wildlife. An example are the wildlife species present in the Rincon Mountains of Saguaro National Monument, Arizona, presented by Davis and Sidner [73]. The highly variable stand structure with multi-storied shrub layers in some southwestern white fir habitat types provides increased microhabitat diversity for birds [101,295]. White fir forests in the Southwest provide habitat for Mexican spotted owls in Arizona, New Mexico [116,194], and Utah [342]; goshawks in Arizona [70,196,256]. Thick-billed parrots, reintroduced in the mountains of southeastern Arizona, occur in mixed-conifer forests with white fir [280]. Several species of amphibians and reptiles may be found in white fir montane mixed conifer forests such as that at upper elevations in Saguaro National Monument [193]. Two species of endangered salamanders (Jemez Mountains salamander and Sacramento Mountain salamander) in New Mexico are found in mixed conifer forests dominated by white fir [251].

More info for the term: tree

Tree

White fir browse is low in protein [92].

AZ CA CO ID ME MA

NV NM OR UT WY

MEXICO

More info for the term: tree

White fir is a valuable ornamental tree. It is often used for ornamental plantings in rural and urban landscapes in northern US cities, because it is attractive and frost-hardy [185,202]. White fir is not, however, very tolerant of air pollution and therefore seems best suited for suburbs or rural areas [175]. White fir eventually attains great size and is best grown in parks or other open public areas. White fir is used extensively in the Christmas tree industry [148,178]. Native Americans used the needles for tea [149].

Because they contain resins, terpenes, and other substances that make the
foliage irritating to the digestive tract, most conifers are not particularly
palatable to grazing animals. White
fir may be slightly palatable to goats [267].
Immature foliage is enjoyed by mule and black-tailed deer [119,189]. White fir seeds are palatable to numerous species of small
rodents, although seeds of Douglas-fir, ponderosa pine, and sugar pine are
preferred [106,250].

More info for the terms: competition, seed, tree

Following stand-replacing fires, white fir reestablishes via wind-dispersed seed. Exposed mineral soil seedbeds created by fire favor initial seedling establishment in white fir [159], but seedling survival is better in partial shade [39]. Therefore, seedlings establish soon after fire if a canopy remains [170], but may take several years to establish if the canopy has been removed.

Fire may encourage growth in white fir by eliminating competition. Evidence from a fire-scarred white fir stump in Oregon shows that after being scarred as a sapling-sized tree, it had growth release [3]. However, trees damaged or weakened by fire are also more susceptible to attack by insects and disease. Fire scars may allow a point of entry for a variety of disease and decay organisms [178,337], and fire-weakened trees that are attacked by insects can be killed within a few years [303].

More info for the terms: cone, cover, layering, litter, monoecious, natural, seed, stratification, tree

White fir reproduction is by seed, and it shows no tendency to reproduce by sprouting or layering. Cuttings can, however, be rooted with or without hormones [178]. White fir is monoecious. The male strobili are 0.2 to 0.4 inches (6-9 mm) long and are densely grouped on the underside of 1-year-old twigs about mid-crown. Female cones are 3 to 5 inches (7-12 cm) long and borne erect on 1-year-old branches, usually in the uppermost crown.

Cone and seed production: Cone and seed production vary with tree size, age and dominance. White fir trees can begin bearing cones at 40 years and continue beyond 300 years [178]. The best producers are mature, healthy dominants in the 12 to 35 inch (30-89 cm) d.b.h. range [120,178]. Cone production is higher on trees near openings [119] and on trees following release [178]. Immature trees can produce heavy seed crops, but their production is more erratic than that of mature trees [119,178]. Pole-sized trees in dense stands will not produce cones unless their leaders reach full sunlight. In mixed conifer forests of California only 4% of understory white fir between 3.6 and 7.5 inches (9.1-19 cm) in diameter produce cones [104]. In Oregon and California, heavy seed crops in white fir are borne on a 3- to 9- year cycle, with fair to good crops occurring every 2 to 5 years, and bumper crops every 5 to 9 years [178]. In the Rocky Mountains, medium to heavy seed crops are produced every 2 to 4 years [104]. Cone production patterns may be different on extreme sites [110,120,157,178]. Because cones are borne on the uppermost part of the crown, any top damage caused by insects, diseases or mechanical agents (e.g. wind and snow) directly reduces cone production. Cones produce about 185 to 295 seeds apiece [104,119]. Seed numbers can reach 600,000/acre (1.5 million/ha) or more where white fir is a site dominant [112,178], and as many as 220,000 where white fir is a minor overstory component [181].

Seed predation: Insects that feed on cones and seeds may seriously reduce yield. Seed chalids typically destroy 8 to 10% of white fir seeds and have destroyed up to 60% of a crop [108]. Cone moths, cone midges, and cone maggots also reduce yields [119]. In California and Oregon, the Douglas squirrel cuts and caches cones, but generally takes less than 1% of the cone crop [106].

Seed dispersal: White fir seeds are released and disseminated by wind as the cone disintegrates on the tree in the fall. Because white fir seed has a short, broad wing relative to its weight, if falls more rapidly and travels a shorter distance from the tree than many of its associated species. Downwind seed spread into an opening is about 1.5 to 2 times the height of the tree [119,178,203]. A small percentage of seeds may be transported greater distances by strong or gusty winds [218].

Germination: After release in the fall, white fir seeds overwinter in or under the snow. This cold, moist stratification is required for germination [108]. Germination of white fir seeds occurs in the spring immediately following snowmelt. Where snowpack is deep, seeds may germinate in, on, and under the snow [157,178]. Of white fir seeds sown in November in white and red fir stands in the Sierra Nevada, 82 to 86% of all germination occurred by May 9, and 96 to 98% by May 22 [39]. Only a small proportion (20-50%) of seeds are viable [178]. Thus, germination is low, averaging about 37% . Under controlled conditions, white fir seeds may be stored for 5 or 6 years, but under natural conditions seeds do not remain viable over 1 year [108].

Seedling establishment and survival: White fir seeds that germinate in the snowpack, above the ground, rarely survive, therefore, seeds that fall before the permanent snow cover are more likely to produce seedlings [119]. Germination and early growth are best on bare mineral soil, though seedlings may establish in soils covered by a litter layer [71,100]. Root systems developed in mineral soil without organic layers are longer, heavier, and have more mycorrhizal root tips than those grown in soil with organic layers [22,178]. Seedlings generally establish best in partial shade, and can establish easily under a closed canopy in dense shade [178]. Shade favors seedling survival in white fir because seedlings are very sensitive to soil drying and heating. Damping off fungi, cutworms, drought, heat, trampling and browsing are responsible for most seedling mortality [39,119]. White fir seedlings are more susceptible to spring frost damage and deer browse than many associated species [157,178,219].

Growth: Once established, white fir grows best in full sun [178]. Shade-tolerant white fir saplings can, however, endure decades of suppression under a closed canopy or in dense brushfields. Leader growth is very slow under these conditions, and suppressed plants may be only 3 feet (0.9 m) tall at 50 years [91]. White fir dramatically increases in diameter and height growth when canopy openings are created, or when its height surpasses surrounding vegetation [100,181].

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):

BLM PHYSIOGRAPHIC REGIONS [43]:




1 Northern Pacific Border

2 Cascade Mountains

3 Southern Pacific Border

4 Sierra Mountains

5 Columbia Plateau

6 Upper Basin and Range

7 Lower Basin and Range

11 Southern Rocky Mountains

12 Colorado Plateau

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More info for the terms: climax, cover, density, fire regime, fire suppression, fire-free interval, forest, herbaceous, mesic, natural, seed, series, shrub, shrubs, stand-replacement fire, succession, tree, xeric

California white fir is a major climax component throughout the mixed conifer forests within its range [178,225]. White fir reproduces abundantly under conditions of dense shade, and it is an aggressive pioneer species as well [201]. Successional relationships of white fir are complicated by floristic differences over its large range of occurrence [188].

The white fir series in the Southwest can have varying mixtures of white fir, with conifer associates dependent on moisture and temperature relationships of the site and stage of succession. The more successful reproduction of white fir is diagnostic of the white fir series [188,232]. Mosaics of contrasting successional stages are considered to be the result of both insects and past fires [247]. Within the mixed conifer type, white fir tends to achieve climax dominance on moist sites [111,328] and in localized areas with long fire-free intervals that give white fir the chance to mature to a point where it is moderately fire-tolerant. In mixed conifer forests with a natural fire regime of low-intensity surface fires, white fir is kept from attaining climax dominance because it is more fire sensitive than its coniferous associates [2,13]. Thus, many white fir habitat types are in mid-successional stages, with various seral species dominating the overstory and white fir dominating the reproductive size classes [40,111]. Seral associates that often dominate a site include ponderosa pine [83,115,185,247,295], Douglas-fir [83,115,185,295], southwestern white pine [185], Gamble oak, New Mexico locust [295], California black oak [113], quaking aspen [40,153,178,230,245,247], and lodgepole pine [245].

White fir will seed into the understory of ponderosa pine stands or in mixtures of ponderosa pine, Douglas-fir, quaking aspen, and southwestern white pine [185]. Many habitat types in the white fir series in the Southwest are dominated by Douglas-fir and ponderosa pine in mid-seral stages, with white fir steadily gaining dominance as succession proceeds [83,295]. Lodgepole pine is a common seral species in the white fir type, with seedlings of white fir in the understory that are less than a meter in height but in excess of 100 years old. Both aspen and ponderosa pine are present at sites where high intensity fires have occurred or where ground fires have slowed or prevented replacement by white fir and Douglas- fir [247]. With fire suppression, white fir is able to mature in the understory with a concurrent decrease in pine reproduction and eventually begins to replace the pines as they succumb to root diseases and bark beetles, resulting in a gradual change in structure and composition in white fir habitat types [27,40,113,115,184,186,258]. White fir will eventually dominate if the fire-free interval is sufficiently long to allow trees to grow to a fire-resistant size, unless another disturbance event gets them. In a Jeffrey pine forest in South Lake Tahoe, California, a disease outbreak killed the Jeffrey pine overstory, releasing the small white firs in the understory which went on to become the predominant species on the site. They then suffered extreme moisture stress form drought and succumbed to a fir engraver attack causing them to die rapidly [270].

It appears that white fir may be an early colonizer of disturbed sites, gradually increasing in dominance over time [34,139,263]. In northeastern California, overgrazing in big sagebrush- steppe communities allowed for the invasion and establishment of white fir in an unusually xeric setting for white fir [258]. White fir may also be a pioneering species in upper elevation meadows within its type where it has been observed to invade by growing near older lodgepole pine [111,178]. White fir is an early seral species at the lowest elevations of the subalpine forest in New Mexico [247].

Following overstory removal (logging or stand-replacement fires) in mixed conifer or white fir forests of the southern Cascades and Sierra Nevada, sites are often dominated by montane chaparral shrubs, primarily ceanothus and manzanita, but also mountain whitethorn, currant and gooseberry (Ribes spp.), chinquapins, and some oaks [65,104,111,149,178]. Seeds of some species may lie dormant in the forest floor for as long as 300 years and germinate following removal of overstory. Sierra mountain misery and grasses may also assume significant roles [178]. Given a nearby seed source and absence of further burning, white fir seedlings can establish under shrubs within about 10 to 20 years [65,218]. A 30 year delay in tree recruitment was observed after a stand-replacement fire in the Lake Tahoe Basin [264]. Given the continued absence of fire, white fir will eventually overtop the shrubs and dominate the site, creating pure stands in otherwise mixed conifer areas [65].

Following overstory removal in mixed conifer or white fir forests in the Southwest, herbaceous species usually dominate the vegetation for the first few years of succession, and diminish in late seral conditions as shading inhibits their growth [83,101,134,157,247,295]. Seral shrubs and trees that follow herbs include aspen, New Mexico locust, Rocky Mountain maple, bush oceanspray, and Gambel oak, and may dominate the site for the next 40 to 100 or more years [83,101,134,153,157,247]. Gradually tree seedlings, including white fir, become established, although growth is slow under the canopy. Scattered conifers emerge above the shrubs after 50 to 100 years. This stage persists for another 50 or more years, with a closed stand of replacement conifers not fully developed until 100-200 years after the fire, the time depending on numerous factors such as shrub density, climatic conditions, availability of tree-seed sources, soil conditions, livestock, wildlife, and human use. Old growth is characterized by conifer overstory and low shrubs in the understory, with possible sparse herbaceous cover [134,157,247]. White fir may establish quickly on mesic sites and dominate early seral stages, while conifers such as southwestern white pine, limber pine and ponderosa pine may dominate the early seral stages on xeric sites [13,225,295].

Crane [69] presents successional trends of white fir habitat types in Colorado that appear reasonable for Utah types as well. In Utah, white fir becomes the dominant climax tree on characteristically cool and dry sites that are usually northern exposures [345]. These sites are apparently too warm and dry for subalpine fir and Engelmann spruce. Although white fir reproduces most abundantly under shade, it also invades open slopes within the mountain-brush zone [201]. White fir and Douglas-fir are replacing brush species on some northern exposures, and, in the absence of fire, these sites may develop into conifer forests [63].

Abies lowiana (Gordon) A. Murray [102]

The currently accepted scientific name of white fir is Abies concolor (Gord.
& Glend.) Lindl. ex Hildebr. (Pinaceae)
[71,89,144,145,146,158,178,191,334,336]. Two varieties are recognized
[71,144,185,186,191,310] based on differences
in morphological and chemical characteristics [124,178,191]:



Abies concolor var. concolor   Rocky Mountain white fir

Abies concolor var. lowiana (Gord.) Lemm.  California white fir




California white fir naturally hybridizes with grand fir (Abies grandis)
in a belt extending from north-west California, across Oregon, and into central
Idaho [146,178,186,347,348,349]. Under controlled conditions, white fir has successfully been crossed
with other firs. Fertile hybrids were produced with the following crosses [278,283]:




Abies concolor var. lowiana X Abies grandis




Abies concolor var. concolor X Abies religiosa

More info for the terms: forest, seed, tree

White fir can be planted on disturbed sites within forest vegetation types where it naturally occurs. It is a good soil stabilizer and may be particularly useful on roadcuts [249]. Fir seedlings exhibit very slow initial growth, and are therefore usually outplanted as 2- to 3-year-old seedlings or 3- to 4-year-old transplants [108]. Transplanting nursery stock is more successful than direct seeding [249]. White fir can be propagated from stem cuttings, which root easily when treated with a rooting medium [88]. Because this wide-ranging tree exhibits a large degree of genetic variation, seed or planting stock for rehabilitation projects is best provided by a local source [214,249]. Methods for collecting, processing, testing, storing, and planting white fir seeds have been discussed in detail [90,108].

More info for the term: tree

Historically white fir was considered undesirable for timber. Now that the availability of premium timber species has declined, white fir is being recognized as a highly productive and valuable tree species and is widely used in the wood products industry [109,148,178]. White fir is a general, all-purpose, construction-grade wood used extensively for solid construction framing and plywood, and to a lesser extent, for pulpwood [148,278]. It is also used for poles and pilings because of its straight grain and low taper, but requires large amounts of preservatives because the heartwood decays rapidly. It is poorly suited for firewood because of its low specific gravity and heat production (80% as much heat by volume as Douglas-fir produces), but it is used for firewood anyway [278].

The most common associates of California white fir in the mixed conifer forests of California and Oregon include grand fir (Abies grandis), Pacific madrone (Arbutus menziesii), tanoak (Lithocarpus densiflorus), incense-cedar (Libocedrus decurrens), ponderosa pine (Pinus ponderosa), lodgepole pine (P. contorta), sugar pine (P. lambertiana), Jeffrey pine (P. jeffreyi), Douglas-fir (Pseudotsuga menziesii), and

California black oak (Quercus kelloggii) (21,47). In the central Sierra Nevada, white fir is a major associate of the relatively rare giant sequoia (Sequoiadendron giganteum) (21). Species mix varies with elevation, site, and latitude. White fir is more abundant on the cooler, wetter sites.

California white fir is a major climax component throughout the mixed conifer forests within its range. It is displaced successionally only at its northern limits in Oregon, where western hemlock (Tsuga heterophylla) and perhaps western redcedar (Thuja plicata) replace white fir as a climax species on moister sites (22). At the upper elevational limits of the mixed conifer forest, white fir dominates, occasionally forming pure stands. Still higher, white fir mixes with California red fir (A. magnifica) in transition to the red fir type. In the southern Sierra Nevada, white fir in this transition zone generally tolerates canopy closure better and dominates on nutrient-rich sites (46). Lodgepole pine is common in these white fir and mixed fir forests, growing around meadows and along streams. Individuals of Jeffrey pine, western white pine (P. monticola), and sugar pine are scattered through the forest (47). In Oregon, scattered western hemlocks are also found (22).

At low elevations California white fir is an aggressive, tolerant species that appears to have been held in check by frequent natural fires. Extensive fire control efforts, however, have reduced fire frequency. As a result, white fir is becoming a major stand component in California at elevations and on sites where originally it was minor (48). Dense fir regeneration beneath older stands of less tolerant trees is common and threatens a major change in species composition. In many places, especially with giant sequoia, such changes are undesirable, and control measures, including reintroduction of fire, are necessary.

In Arizona and New Mexico, Rocky Mountain white fir is a major climax component in 11 major habitat types and phases (42). Listed in sequence-from warm and dry low-elevation to cool and moist high-elevation environments-these habitat types include ponderosa pine/Arizona fescue, white fir/Arizona fescue, white fir-Douglas-fir, white fir-Douglas-fir/Gambel oak, white fir-Douglas-fir/Rocky Mountain maple, and blue spruce-Engelmann spruce/forb (Senecio spp.). White fir is a minor climax component in the Douglas-fir-southwestern white pine/grass (Muhlenbergia spp.), blue spruce-Douglas-fir, and blue spruce/sedge (Carex spp.) habitat types. Additional associates are subalpine and corkbark firs. Aspen (Populus tremuloides) is a major seral species in many areas.

A variety of woody brush species can assume major importance in much of the white fir range, particularly in mixed conifer zones. Following drastic disturbance, brush can quickly occupy and dominate a site. Common species include mountain whitethorn, deerbrush, and other Ceanothus species, manzanita (Arctostaphylos spp.), currant and gooseberry (Ribes spp.), several chinkapins (Castanopsis spp.), and a few oaks (Quercus spp.) (21,22). In addition to severely competing for light and moisture (14), at least one Ceanothus species contains allelopathic chemicals in its foliage that suppress radicle growth of white fir (12). Mycorrhizal associations are thought to protect white fir roots from allelopathic chemicals produced by bracken fern (Pteridium aquilinum) (1). Other species of lesser vegetation that sometimes assumes a significant role includes bearclover (Chamaebatia foliolosa) and several grasses. Seeds of some species can lie dormant in the forest floor for as long as 300 years and germinate following removal of forest cover by fire or harvesting. In areas where brush is vigorous, tree seedlings that can survive and grow under brush cover are favored, provided the time between fires is long enough (e.g., 20 years) to allow the fir to establish crown dominance (13,21,40). Pure stands of white fir frequently begin this way.

White fir is represented in at least 14 forest cover types of western North America. Pure stands are White Fir (Society of American Foresters Type 211) (19). It is a major component in Sierra Nevada Mixed Conifer (Type 243) and is also found in the following types:

206 Engelmann Spruce-Subalpine Fir
207 Red Fir
210 Interior Douglas-fir
216 Blue Spruce
217 Aspen
229 Pacific Douglas-fir
231 Port Orford-cedar
237 Interior Ponderosa Pine
244 Pacific Ponderosa Pine-Douglas-fir
245 Pacific Ponderosa Pine
247 Jeffrey Pine
256 California Mixed Subalpine

Rocky Mountain white fir grows on high mountains, typically with long winters, moderate to heavy snowpacks, and short growing seasons. Annual precipitation ranges from about 510 mm (20 in) to slightly more than 890 mm (35 in). In the central Rocky Mountains, rainfall is distributed evenly during the summer months. In Arizona and New Mexico, summer tends to be wetter than spring (37).

California white fir grows in cold, high elevations and in warm-to-hot low elevations. Precipitation ranges from 890 mm (35 in) to 1900 mm (75 in) or more per year. California white fir grows best in the southern Cascades and western slopes of the Sierra Nevada, where precipitation is generally between 990 and 1240 mm (39 to 49 in). Locations receiving 1500 mm (59 in) or more are not uncommon, however (21). Essentially, all precipitation occurs during the nongrowing season. Fall and early spring rains are a major portion of the precipitation at lower elevations and winter snowpacks provide more than 80 percent of the moisture at high elevations (57). Occasional summer thundershowers are usually light.

Growth studies on Swain Mountain Experimental Forest, in the southern Cascades of California, indicate that high-elevation stands of California white fir grow best in years with precipitation as low as 38 percent of normal (45). At these elevations low precipitation usually means early snowmelt and a longer growing season (54).

White fir saplings and poles are susceptible to fire damage or kill, but trees become more resistant to both with age and size. White fir is considered more fire resistant than its associated species at high elevations (37,41), but less resistant than its associates at low elevations (47). Fire scars, commonly found in old-growth stands, provide an entry court for a variety of disease and decay organisms.

White fir is sensitive to spring and fall frosts. Spring frosts can kill developing buds as well as foliage. Damage to established trees, other than Christmas trees, is not usually significant. On some sites, repeated damage to new fir growth can give a competitive advantage to more resistant species. Cold damage to mature trees takes the form of frost cracks and ring shake. Frost cracks are associated with some rot and decay loss (9).

Sudden rises in temperature during May and early June can cause damage nearly identical to that of spring frosts. Sun-scalding following thinning is rare in mature trees, although young, thin-barked trees are susceptible. When white fir boles are injured, recovery is slow (9).

Compared to its associated species, white fir is moderately susceptible to ozone damage. Although fir grows faster than associated species in southern California, diameter growth is affected by oxidant damage as much as that of Ponderosa pine (43). White fir is more resistant to fluoride damage than Douglas-fir or ponderosa pine (37).

As intensive management of this productive species increases, so will the importance of mechanical injury. Studies in Oregon and California have shown that conventional logging techniques for thinning or partial cutting damaged 22 to 50 percent of the residual stand. Seventy-five percent of these wounds were at ground level, where infection by some decay-causing fungus is almost certain (3). Loss of volume by time of final harvest can be considerable.

Two parasitic plants, white fir mistletoe (Phoradendron bolleanum subsp. pauciflorum), a true mistletoe, and white fir dwarf mistletoe (Arceuthobium abietinum f. sp. concoloris), cause major damage to white fir (9). In Arizona, Mexico, and the central to southern Sierra Nevada of California, white fir mistletoe is a serious problem on large old trees. Heavy infections cause spike tops, loss of vigor, and increased susceptibility to bark beetle attack. Dwarf mistletoe is a major problem from the southern Sierra Nevada north into Oregon. It is found elsewhere throughout the native range of white fir in coastal and southern California, Nevada, and Arizona (39,63).

One-third of the white fir stands in California are severely infested by dwarf mistletoe and the parasite is present in other forest types that contain white fir. Heavily infected trees suffer significant growth losses and are prone to attack by Cytospora abietis, a fungus that kills branches and further reduces growth. Because of reduced vigor, infected trees are more susceptible to bark beetle attack and various diseases (50,51). Heart rots, entering through open mistletoe stem cankers, increase mortality of old-growth trees through stem breakage.

Changes in wood structure in the large stem bulges caused by dwarf mistletoe infections reduce the strength of lumber produced. Current lumber grading practices, however, are not adequate to identify the affected wood (61).

Dwarf mistletoe need not be a problem in young managed stands because three factors make damage subject to silvicultural control. The parasite is host specific: white fir can be infected only by A. abietinum f. sp. concoloris, which in turn can parasitize only one other fir, grand fir. Small trees (less than 1 m [3.3 ft] tall) are essentially free from infection even in infested stands. Infected young firs free from new overstory infection outgrow the spread of mistletoe if height growth is at least 0.3 m (1 ft) per year (50).

Annosus root rot (Heterobasidion annosum) is present in all conifer stands and may become a major disease problem as management of white fir increases. Once established, the disease affects trees within a slowly expanding, circular infection center. Spread from tree to tree is through root contacts. New infection centers begin by aerial spread of spores and infection of basal wounds and freshly cut stumps. In true fir, annosus root rot usually does not kill directly but produces considerable moisture stress and loss of vigor that predispose the tree to attack by bark beetles, notably Scolytus. Direct damage resulting from infection is restricted primarily to heart rot of butt and major roots, leading to windthrow and stem breakage (9). Some degree of control is available through silvicultural means and use of borax on freshly cut stumps.

Other rots of major significance include the yellow cap fungus (Pholiota limonella), Indian paint fungus (Echindontium tinctorium), and white pocket rot (Phellinus pini) (9). Yellow cap fungus causes heavy losses from butt rot and enters through fire scars and basal wounds (9). Indian paint fungus is a major heart rot organism. This fungus probably infects fir in the same manner it does western hemlock (3). Entry is through branchlets less than 2 mm (0.08 in) in diameter. The fungus can remain dormant for up to 50 years before being activated by injury to the tree (18). Rot commonly extends 3 m (11 ft) below and 6 m (20 ft) above each characteristic fruiting body (4). No effective control is known although trees less than 40 years old are relatively free of rot because they have so little heartwood. In the white fir-grand fir complex of Idaho, the fungus was found in 97 percent of the trees that had decay. Almost 80 percent of the decay in old-growth grand fir-white fir stands of eastern Oregon and Washington is caused by Indian paint fungus; in California, it is much less common (9).

Insects from seven genera attack white fir cones and seeds. Two cause damage with considerable loss of seed. Seed maggots (Earomyia spp.) are the most abundant and damaging. The fir cone looper (Eupithecia spermaphaga) covers almost the entire range of white fir and periodically causes considerable local damage (27).

Although many insects feed on white fir foliage, few cause significant damage as defoliators. The most destructive of these is the Douglas-fir tussock moth (Orgyia pseudotsugata). Over most of its range the tussock moth shows equal preference for true fir and Douglas-fir foliage. Epidemic outbreaks, although sporadic, are explosive and damaging. In California, white fir is the preferred host, but outbreaks have not reached the severe levels sustained elsewhere (27). Occasionally, localized outbreaks result in increased stand growth as mortality of subordinate trees "thin" an overdense stand (59,60).

The western spruce budworm (Choristoneura occidentalis) is the most destructive defoliator in western North America, causing serious damage in Canada and the Rocky Mountains and Pacific coast regions of the United States. Some outbreaks are short lived, but some continue for 20 years or more. Although initial damage is to new foliage and buds, trees can be completely defoliated in 4 to 5 years. Ultimate damage ranges from minor growth loss to major tree mortality over extensive areas, depending on severity and duration of the outbreak (27).

A similar species, the Modoc budworm (Choristoneura retiniana [= viridis]), is endemic to the Warner Mountains of northeastern California and southeastern Oregon. Damage to California white fir in the Warner Range has been sporadic and light (27).

The New Mexico fir looper (Galenara consimilis) is restricted to New Mexico and can be a serious problem locally on white fir. Weevils of the genus Agronus attack foliage of young trees and may cause concern with intensive forest management. Sawflies (Neodiprion spp.) are generally not a problem-but are potentially damaging in dense stands of young fir. In California, a species of Neodiprion sawfly has reached epidemic levels locally on white fir. White fir needleminer (Epinotia meritana) covers the full range of white fir and can cause extensive branch kill predisposing trees to bark beetle (Scolytus) attack (27).

Cutworms (Noctuidae) can be a problem in nurseries and, more especially, in natural regeneration areas. Cutworms have been responsible for more than 30 percent of the seedling mortality in California (21,28).

The most damaging white fir pest is the fir engraver beetle (Scolytus ventralis). This bark beetle is found over the entire range of white fir and causes serious damage nearly everywhere. Mortality equivalent to an estimated 2.4 million m³ (430 million fbm) of growing stock is caused each year in California alone. Losses during epidemics are even larger (27). The fir engraver can attack any tree, but those suffering from root rot infections or tussock moth attack are especially vulnerable. In general, anything that reduces tree vigor, such as mistletoes, Cytospora, drought, or fire, increases susceptibility to attack (20). Several other bark beetles-including one species of Pseudohylesinus and two species of Scolytus, the roundheaded borer (Tetropium abietis) and the flatheaded fir borer (Melanophila drummondi)- frequently join the fir engraver in attacking and killing individual trees. In epidemic conditions, however, mortality is primarily caused by the fir engraver. Maintenance of stand health and vigor is the only known control (27).

Locally, small rodents can cause significant loss of seed and occasionally girdle seedlings. Pocket gophers limit regeneration in many areas, particularly clearcuts, by feeding on fir seedlings during winter and spring. Pocket gophers in combination with meadow voles and heavy brush can prevent conifer establishment for decades (21,37). Pocket gopher damage occurs on trees of all ages and sizes. Feeding on root tissues at the root crown has girdled saplings up to 12.7 cm (5 in) in diameter at breast height (d.b.h.). In at least one place, such feeding has resulted in death of mature trees up to 93.7 cm (36.9 in) d.b.h. (32). Direct control of pocket gopher is difficult and expensive. Indirect control by habitat manipulation offers some possibilities.

Spring browsing of succulent growth by deer and other big game animals can retard height growth for many years. Normally, trees are not killed, and most can grow rapidly once browsing pressure is removed. In managed stands, however, reduced height growth can result in significant economic loss. Damage by big game can be severe in the Southwest. Damage from livestock grazing is limited primarily to trampling and appears to be decreasing as the number of cattle on the open range decreases (37).

White fir is monoecious. The reddish male strobili (cones) are generally less than 1.6 cm (0.6 in) long and are densely grouped on the underside of 1-year-old twigs about midcrown. Female cones are borne erect on 1-year-old branches, usually in the uppermost crown although both male and female cones are occasionally found on the same branch. California white fir flowers in May or June and fertilization occurs shortly thereafter. Flowering of Rocky Mountain white fir at the higher elevations may be delayed and extend into July. Female cones reach full size, 7.5 to 13 cm (3 to 5 in) long, in late summer and turn from greenish or purplish to brown when mature (21,52). Cone specific gravity is about 0.85 when mature (52). The seed matures in September, up to 3 weeks before seedfall (44).

White fir is an adaptable and genetically plastic species. Throughout its range, elevational and latitudinal gradients are reflected as changes in stomatal number and arrangement, needle shape, growth rate, phenology, (34), and trachied length (16).

Interspecific crossbreeding is reasonably easy between fir species within the same group (e.g., A. concolor and A. grandis within Section Grandes), but difficult to impossible between sections (15,35,55). In the northern portion of its range, California white fir intergrades and hybridizes freely with grand fir, both being in the Section or group Grandes (15). The species are morphologically, ecologically, and chemically distinct (20,31). They differ in stomatal number and reaction to moisture stress (63). Grand fir grows most abundantly on cool, moist sites and white fir on warmer, drier sites. Grand fir has a higher incidence of heart rot than white fir. Grand fir bark has a red-purple periderm and is high in camphene. White fir bark periderm is yellowish and camphene content is low (62). Hybrid trees are intermediate in all of these characteristics, including incidence of heart rot, which may be more closely related to cool, wet sites than to genetic differences (26).

Over a large area from northwestern California through central Oregon and into central Idaho, identification of the two species is difficult and sometimes impossible. White fir in this region is called "grandicolor."

The capacity of white fir to produce large volumes per unit area was recognized before the species was considered of commercial value. As recently as 1962, white fir was regarded as undesirable in forests managed for timber. The productivity of fully stocked, 100-year-old stands in California (53,59) and eastern Washington and Oregon (11) on good [Site Index 27 m (90 ft)] and average [Site Index 18 m (60 ft)] sites is evident (table 1). The unusual productivity is possible, at least in part, because this species can grow in stands of high basal area. In mixed-conifer stands, white fir still demonstrates a high level of productivity, although its height growth begins to decrease earlier than that of associated species (10,17).

Table 1- Volume in white fir stands in California and eastern Oregon and Washington at age 100 (11,53,59) Site index¹
and location
Basal area
Volume 27.4 m or 90 ft m²/ha ft²/acre m³/ha ft³/acre California 108 471 1,372 19,600 Oregon and   Washington 80 349 1,066 15,230 18.3 m or 60 ft California 91 397 805 11,500 Oregon and   Washington 67 291 633 9,039 ¹Average height of dominant trees at base age 50 years.

White fir has several features of major silvicultural significance. The species is classified as shade tolerant, more so than most of its mixed conifer associates (41). Relative shade tolerances of red fir and white fir in the high-elevation burning transition zone are uncertain. In the northern end of their respective ranges, shade tolerance may be affected by the evident exchange of genetic material with associated species-white fir with grand fir (A. grandis) and red fir with noble fir (A. procera) (2). White fir is capable of rapid growth to a large size and grows best in full sunlight. It can survive for exceptionally long periods as a suppressed tree and still respond to release by increasing growth dramatically. The time period before growth begins to accelerate varies depending on crown condition at time of release (36). Seed production increases following release even on dominant trees (38).

Because of these features, white fir is a major management consideration in any mixed conifer stand where it is a component. Partial cutting and most shelterwood cuttings favor white fir and increase its importance in the stand. Prescribed burning in areas where white fir is not desired may be the only reasonable way to control its abundance. Underburning in groves of giant sequoia to control young white firs and to create seedbeds for giant sequoia reproduction is a special example.

To manage pure stands of white fir is relatively easy and, with intensive management, young stands can be extremely productive. White fir can be regenerated naturally or artificially. Natural regeneration can be achieved through clearcutting as long as the maximum downwind width of openings does not exceed 1.5 to 2 times the height of trees left as seed sources. Shelterwood cuttings have been successful in establishing natural regeneration (30). On sites where brush competition is a problem, planting under shelterwood has promise. Because of high growth rates in dense, even-aged stands, even-aged management is the likely choice. Uneven-aged management is theoretically possible, however, because of the species' shade tolerance and response to release. The long period of extremely slow growth under shade and the incidence of dwarf mistletoe infestation make uneven-aged management questionable, however.

Root systems of mature forest trees, including white fir, have not been the subject of much research. What little is known has been gleaned from observations of windthrown trees. Mature white fir rooting habit appears to be fairly adaptable: deep and intensive where soil conditions permit or shallow and widespread where rocks or seasonal water tables limit effective soil depth. There is no strong tendency to maintain a single deep taproot, although rapid taproot development is critical for survival of new germinants in the dry summer climate.

White fir is susceptible to windthrow following partial cutting, especially when marginal codominant and lower crown classes are left as the residual stand. Root diseases contribute significantly to lack of windfirmness. Root grafting between firs is common and is frequently demonstrated by living stumps (21). Root grafting is also a factor in the spread of root rots.

Effects of mycorrhizal associations are beginning to be explored. Early information indicates that these root and fungi relationships are significant, especially in establishment and early growth on poor sites, and that bare mineral soil promotes the association (6).

Studies of white fir seed and cone production in Oregon, California, and the Rocky Mountains indicate that heavy crops are borne on a 3- to 9-year cycle (25,29,37). Adequate to good crops are produced more often, generally every 2 to 5 years. On extreme sites, cone production patterns may be different.

Seed size varies widely and a kilogram may contain between 18,960 and 39,070 seeds (8,600 to 17,700/lb) (50). Relatively small proportions (20 to 50 percent) of white fir seed are sound, even in good seed years (21,52). Seed numbers, however, can reach 1.5 million/ha (600,000/acre) or more (24,30). Seed production varies with tree age, size, and dominance. The best, most reliable producers are mature, healthy dominants in the 30- to 89-cm (12- to 35-in) d.b.h. range (29). White fir trees can begin bearing cones when only 40 years old and continue beyond 300 years (45). Immature trees can produce heavy seed crops, but their performance is more erratic than that of mature trees (28).

Because cones are borne almost exclusively in the uppermost part of the crown, any top damage caused by insects, diseases, or mechanical agents (for example, wind and snow) directly reduces cone production. Large old trees are prone to such damage. Trees that have lost their tops, however, can frequently develop new terminals and resume cone bearing.

Studies in California indicate that mature dominants along the edge of a clearcutting produce between 1.5 and 6.7 times as many cones as similar trees in adjacent closed stands (28). Regeneration data, also from California, indicate that mature trees left in seed tree or shelterwood cuts increase seed production (42).

Seeds are released as cones disintegrate on the tree. The white fir seed has a relatively short, broad wing for its weight and falls more rapidly than a pine or spruce seed. Because most dissemination is by wind, the distance of seed spread is more limited than that of many associated species. Reliable downwind seed spread into an opening generally is limited to 1.5 to 2 times tree height (28).

White fir seeds germinate in the spring immediately following snowmelt (37) or, where snowpacks are deep, in, on, and under the snow (23). In the Rocky Mountains, white fir germination in spring is in contrast to that of other major species in the mixed conifer type that do not germinate until the summer wet season (37). Seeds that germinate several centimeters above ground in the snowpack rarely survive after snowmelt. Seeds that fall before permanent winter snow cover, therefore, are more likely to produce seedlings. Germination and early growth are best on bare mineral soil. Root systems developed in mineral soil without organic layers are longer, heavier, and have more mycorrhizal root tips than those grown in soil with organic layers (6). White fir seedlings are epigeal.

In general, white fir becomes established best in partial shade, but once established grows best in full sunlight. It is less tolerant of shade than associated true firs (except red fir), is slightly more tolerant than Douglas-fir, and is much more tolerant than pines or oaks (37,41,56). Because white fir can survive and grow beneath heavy brush cover and eventually overtop the brush and dominate the site, many pure stands exist in otherwise mixed conifer areas (36).

Previously it was thought that white fir growth was extremely slow for the first 30 years. It appears now, however, that slow growth beyond 5 years is not inherent and may be caused by environmental conditions, such as prolonged shading and browse or frost damage. White fir is more susceptible to spring frost damage and deer browse than many associated species (37,41).

Radial growth begins before height growth and lasts longer. Height growth begins later in white fir than in associated species at mid-elevations and lasts only about 6 weeks. Occasionally, in California, height growth begins again in late summer. The resulting succulent growth is subject to frost kill. White fir trees from low-elevation seed sources are twice as likely to increase height growth in response to moisture supplied during the summer than are white fir from high elevations or red fir from any elevation (33).

Throughout its natural range, white fir grows on a variety of soils developed from almost every kind of parent material. These materials include recent volcanic and igneous rocks of nearly all compositions, large areas of intrusives (mostly granites), and various metamorphics, including serpentine. Sedimentary materials range from limestone, sandstone, and shale to unconsolidated Pleistocene lake deposits (5,21,22). These soils fall into the Inceptisol, Entisol, Alfisol, and Ultisol soil orders. Alfisols are most frequently found at the lower elevations in California where white fir is a component of the Sierra Nevada Mixed Conifer Type.

White fir is generally tolerant of a wide range of soil conditions, nutrient availability, and pH values. It seems to be more dependent on moisture availability and temperature than on soil series. In at least one area of summer-dry Mediterranean climate, productive stands of white fir may utilize water obtained from shattered or otherwise porous bedrock well below the maximum soil depth (8). Growth and development are best on moderately deep and well-drained sandy-loam to clay-loam soils, regardless of parent material. High-elevation fir forests respond strongly to nitrogen fertilizer because low temperatures inhibit decay and natural release of nitrogen from the forest floor (49).

California white fir is moderately sensitive to excess soil moisture and invades high-elevation meadows by growing near older lodgepole pine, taking advantage of relatively dry ground created by the pine roots. A similar pattern of meadow invasion can develop where radiational heat loss on clear, cold nights is significant. In these situations, the frost-sensitive fir is protected by the pine foliage.

The species grows on various types of terrain, including the extremely steep and unstable slopes of the geologically young Coast Ranges in northwestern California. It develops best on gentle slopes and level ground. Elevations range from a minimum of 600 m (1,970 ft) in the headwaters of the Willamette River of central Oregon to a maximum of almost 3400 m (11,150 ft) east of the continental divide in central Colorado. Lower and upper elevational limits increase from north to south and from west to east as temperatures, distance from the Pacific Ocean, or both increase. Most California white fir in the Sierra Nevada is found at elevations between 1200 and 2100 m (3,900 and 6,900 ft). It grows at elevations of 1500 to 3000 m (4,900 to 9,800 ft) in the San Bernardino Mountains of southern California. Rocky Mountain white fir is found most frequently at elevations between 2100 and 2700 m (6,900 and 8,900 ft) (21,22,47).

White fir is a general, all-purpose, construction-grade wood used extensively for solid construction framing and plywood. A significant portion of the Christmas trees used in California are young white fir. These trees are harvested from natural stands, from regeneration areas where the trees are cultured for as long as 11 years before harvest, and from areas used specifically for Christmas tree production.

Detailed and exact wildlife censuses for large areas do not exist, and any listing of species numbers associated with a major forest type is an approximation. There are, however, about 123 species of birds found in the white fir type of California, 50 of which are associated primarily with mature forests. Perhaps because of the dense nature of most true fir forests in California, there are only 33 species of mammals commonly present and of these only 7 are generally associated with mature forests. Reptiles are represented by 17 species, mostly at lower elevations. Only eight are regularly associated with mature forests (58).

White fir shows no tendency to reproduce by sprouting or layering, but cuttings can be rooted with or without hormones. The relative ease with which cuttings from juvenile material can be rooted provides an opportunity to produce genetically selected planting stock at relatively low cost.

The native range of white fir extends from the mountainous regions of the Pacific coast to central Colorado, and from central Oregon and southeastern Idaho to northern Mexico (21).


- The native range of California white fir (left) and
Rocky Mountain white fir (right).

Pinaceae -- Pine family

Robert J. Laacke

Long considered undesirable for timber, white fir (Abies concolor) is finally being recognized as a highly productive, valuable tree species. White fir reaches its best development and maximum size in the central Sierra Nevada of California, where the record specimen is 58.5 m (192 ft) tall and measures 271 cm (106.6 in) in d.b.h. (7). Large but not exceptional specimens, on good sites, range from 40 to 55 m (131 to 180 ft) tall and from 99 to 165 cm (39 to 65 in) in d.b.h. in California and southwestern Oregon and to 41 m (134 ft) tall and 124 cm (49 in) in d.b.h. in Arizona and New Mexico (37).

Needle form and terpene content vary sufficiently across the wide range of the species to warrant definition of two varieties: the typical var. concolor, white fir, often called Rocky Mountain white fir, occupies the eastern and southwestern part of the range; var. lowiana (Gord.) Lemm., California white fir, grows in the western range (31). In this paper, "white fir" applies to both varieties.

Tree, Evergreen, Monoecious, Habit erect, Trees without or rarely having knees, Primary plant stem smooth, Tree with bark smooth, Tree with bark rough or scaly, Young shoots 3-dimensional, Buds resinous, Leaves needle-like, Leaves alternate, Needle-like leaf margins entire (use magnification), Leaf apex acute, Leaves < 5 cm long, Leaves > 5 cm long, Leaves < 10 cm long, Leaves grey-green, Leaves not blue-green, Leaves white-striped, Needle-like leaves flat, Needle-like leaves not twisted, Needle-like leaf habit erect, Needle-like leaf habit drooping, Needle-like leaves per fascicle mostly 1, Needle-like leaf sheath early deciduous, Needle-like leaf sheath persistent, Twigs glabrous, Twigs pubescent, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Berry-like cones orange, Woody seed cones > 5 cm long, Bracts of seed cone included, Seeds tan, Seeds winged, Seeds unequally winged, Seed wings prominent, Seed wings equal to or broader than body.

Abies concolor, the white fir or Colorado fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Cascade Range and southern Rocky Mountains, and into the isolated mountain ranges of southern Arizona, New Mexico, and Northern Mexico. It naturally occurs at elevations between 900 and 3,400 metres (3,000 and 11,200 ft).

It is popular as an ornamental landscaping tree and as a Christmas tree.