Abies concolor

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.

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.

General: Pine Family (Pinaceae). White fir is a large coniferous tree, growing up to 55 m tall and having a dbh of up to 1 to 2 m, depending on location. The bark is smooth, whitish-gray, and occasionally blistered with resin vesicles, becoming thick, hard and irregularly furrowed with age. The crown tends to be symmetrical and dome-shaped, although the varieties of white fir may exhibit differences in crown shape. California white fir has a cylindrical crown while Rocky Mountain white fir has a broader crown. Branches are short and stout, arranged in whorls of 4 or 5. Buds are blunt. Leaves (needles) are 3-7 cm long, loosely 2-ranked, rounded at the ends, and curved upward. A waxy covering give the needles a bluish cast. Needles also have two white lines on their undersides. Cone production varies by site, tree size, and age. White fir trees begin cone production at about 40 years and bear cones at the upper third of the crown. Cones are 10-13 cm long, greenish-yellow becoming dark purple, produce about 185-295 seeds each, and shatter upon maturity. The seeds are released in the fall and germinate in the spring.

Key characteristics of white fir include the similar coloring on both upper and undersides of the needles, smooth bark with resin blisters, long needles (in comparison to other fir species), resinous buds, circular leaf scars, and a citrus odor that is released when the needle is broken.

Morphological and chemical characters, such as needle tip shape, stomatal arrangement, and terpene content, separate the two white fir varieties.

Distribution: White fir is native to the western United States, from Idaho, south through Colorado and New Mexico, and west through California and Oregon. The Great Basin creates the gap between the varieties. Rocky Mountain white fir occurs in the central portion of the white fir range, from southeastern California, Arizona, and New Mexico to southeastern Idaho and Colorado. It has also been planted in the New England states. California white fir occurs from central California into western portions of Nevada and southwest Oregon. It has been reported in southern California, although there is no confirmation that these plants are not the Rocky Mountain variety.

For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.

Habitat: In the mixed conifer forests of California and southern Oregon, white fir may form pure stands or share dominance with species such as incense-cedar, ponderosa pine, lodgepole pine, sugar pine, Jeffrey pine, and Douglas pine. It is also a secondary species in subalpine woodlands represented by whitebark pine, limber pine, mountain hemlock, lodgepole pine, western white pine and foxtail pine. California white fir is one of the coniferous dominants of the California hardwood forests. In the mixed-conifer forest of the Sierra Nevada Mountains, it may share dominance with incense cedar, ponderosa pine, sugar pine, and Douglas fir. The mesic sites at upper elevations of the Sierra Nevada Mountains are referred to as the white fir zone.

Within the Cascade Range of northern California and central Oregon, the white fir zone occurs at elevations above 1500 m. It is the dominant species, having 18 known associations with species like lodgepole pine, western serviceberry, mountain hemlock and Pacific rhododendron. It is also found within mixed conifer stands at mid-elevations.

White fir is an indicator species of the lower elevation limit of montane forest vegetation in the Klamath Mountains of California and Oregon. At higher elevations, white fir shares dominance with red fir. In the mountain ranges of southern California, white fir becomes the dominant species at higher elevations. It is associated with sugar pine, incense cedar, and western juniper.

The white fir series in the major mountain ranges in the southwest can have any mixture of white fir with Douglas fir, Engelmann spruce, blue spruce, subalpine fir, ponderosa pine, and southwestern white pine. It is a dominant or climax species of several habitat types and series in Arizona, New Mexico, Utah, and Colorado.

In Utah, white fir occurs throughout the higher mountain ranges of the northwestern region and increases in importance through southern Utah. It occurs in subalpine zones with Engelmann spruce and blue spruce in the Douglas fir series and ponderosa pine habitat types.

In southern Colorado and northern New Mexico, white fir is a co-climax species with Douglas fir and is associated with blue spruce, limber pine, ponderosa pine, Engelmann spruce, subalpine fir, quaking aspen, and Rocky Mountain juniper. The white fir-Douglas fir-pondersoa pine series is the most widespread and one of the most varied types in Arizona and New Mexico. In mixed conifer forests, dominated by the white fir-gambel oak habitat type, white fir shares climax status with Douglas fir. Other associates include Chihuahua pine, Rocky Mountain lodgepole pine, Mexican pinyon, and New Mexico locust.

White fir is widespread in riparian areas of Utah, Wyoming, Colorado, Arizona, and New Mexico. It is associated with boxelder and narrowleaf cottonwood in Utah, blue spruce and lodgepole pine in Wyoming, and with blue spruce, cottonwood species, and Rocky Mountain maple in Colorado, Arizona, and New Mexico. More detailed habitat descriptions can be found in Zouhar (2001).

Abies grandis var. concolor, balsam fir, Colorado white fir, Picea concolor, Pinus concolor, silver fir, and white balsam. There are two varieties of white fir, sometimes recognized as separate varieties and sometimes grouped under the white fir blanket. They are Rocky Mountain fir (Abies concolor var. concolor) and California white fir (Abies concolor var. lowiana, also known as Sierra white fir).

AZCACOIDMEMA
NVNMORUTWY
MEXICO

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).

Abies concolor Lindl.:
Mexico (Mesoamerica)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Abies lowiana var. viridula Debreczy & I. Rácz:
Mexico (Mesoamerica)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Abies concolor (Gordon & Glend.) Lindl. ex Hildebr.:
Mexico (Mesoamerica)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

The USDA hardiness zones of white fir range from 3 to 7. It occurs at varied elevations, ranging from 900 m to over 3000 m. Annual precipitation varies among white fir sites from 350 mm to 1240 mm. White fir tends to occupy more mesic sites at lower elevations and more xeric sites at upper elevations. It grows on acidic soil, most types of parent material, and is tolerant of a wide range of soil conditions, nutrient availability, and pH. It grows best on moderately deep and well-drained sandy- or clay- loam soils. It is moderately sensitive to excess soil moisture and is less tolerant of shade compared to associated true firs. Dense shade will decrease the growth rate, but will not kill the tree.

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.

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.

Picea concolor Gordon & Glendinning, Pinetum, 155. 1858

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).

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).

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

Systems

• Terrestrial

Germination and early growth are best if seeds have fallen on bare mineral soil before the permanent snow cover has fallen. Root systems are longer, heavier, and have more mycorrhizal root tips if grown in bare mineral soil. Seedlings are best established in partial shade, but can also establish in dense shade. Once established, it grows best in full sun.

Foodplant / parasite
aecium of Milesina dieteliana parasitises live Abies concolor

Foodplant / pathogen
aecium of Milesina scolopendrii infects and damages live Abies concolor

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

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 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).

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 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.

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).

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 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).

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 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 following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 3
Species With Barcodes: 1

Year Assessed

• Needs updating

Assessor/s

Reviewer/s

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Scattered through the Rocky Mountains and in Oregon and the California Sierras; it is of limited occurrence and rather small size in the mountains of northwestern Mexico.

Rocky Mountain white fir (Abies concolor var. concolor) is protected in Nevada as a Christmas tree. 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).

Dwarf mistletoe is a common pest of white fir. The parasitic plants germinate on white fir branches and force their roots into the phloem of the host branch. Dwarf mistletoe weakens the tree and leaves it susceptible to fungal infections and insect attacks. It also creates stem cankers that leave the wood weak and unsuitable for use as lumber.

Wounding, as a result of mechanical injuries, fire, insects, or frost cracks, promotes or provides entrance for fungi into white fir trees. Annosus, Armillaria, laminated root diseases, yellow cap fungus, Indian paint fungus, and white pocket rot reduce plant productivity and cause wood decay and mortality. Fungal infections also promote susceptibility to insect infestations.

The fir engraver beetle (Scolytus ventralis), a member of the bark beetle family, causes high mortality in white fir stands. The beetle bores holes into the main stem, often in bark crevices at the branch and trunk junctions. Once under the bark, adults engrave egg galleries into the sapwood, disrupting the flow of water and nutrients to that portion of the plant. The appearance of yellowed or reddened branches on an otherwise green tree is early evidence of fir engraver infestation. Fir engravers can kill the plant. The only known preventative is proper maintenance of white fir trees.

White fir in shallow soils can be damaged by strong winds. The chances of windthrow are increased when neighboring trees are removed.

The USDA NRCS Plant Materials Program has not released white fir cultivars for conservation use.

Ornamental cultivars are somewhat available from commercial growers in ball and burlap form:

‘Blue Cloak’

‘Blue Globe’

‘Blue Select’

‘Candicans’

‘Compacta’

‘Conica’

‘Dwarf Blue’

‘Gables Weeping’

‘Glenmore’

‘Nana’

‘Sherwood Blue’

‘Winter Gold’

White fir is produced by seeds. Seeds are ready for collection when the cone easily breaks apart. A cold stratification period up to 60 days is required. Germination will occur under an alternating temperature cycle of 30^oC daytime and 20^oC nighttime temperatures.

White fir is easily transplanted, although it is somewhat sensitive to being transplanted in autumn. If planted in autumn, care should be taken to fertilize, thoroughly water, adequately mulch, amend the soil, and avoid winter salt spray. These care practices will enhance the chances for survival during the first winter.

White fir is easily killed by fire. Low branches provide a ladder for understory fire to reach the canopy. Prescribed burning is recommended if pure stands of white fir are not desired and to reduce fuel loading. Burns will promote suckering of other tree species so that pure stands of white fir will not form.

White fir can be managed for timber harvest. Shelterwood methods have the best regeneration results. Some overstory removal provides enough light for white fir regeneration, but also provides enough shade to prevent the regeneration of other species. Many white fir stands have been managed using even-aged management techniques.

Mycorrhizal associations are important to the growth and health of white fir. Bare mineral soils promote these associations that aid in establishment on poor sites.

Lack of management in white fir stands may increase the trees’ chances of susceptibility to insect pests and diseases.

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 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.

Ethnobotanic: Native Americans used white fir for medicine, building material, and for making household items. The needles were used to relieve pain caused by rheumatism and pulmonary ailments. The resin was used to heal cuts, sores, and boils and was also decocted for the treatment of venereal diseases. Bark infusions were used to remedy tuberculosis.

Bark was used to dye buckskin a tan color. Branches were used to line storage containers and to make pipe stems. The plant was used to decorate ceremonies and houses.

Ornamental: White fir is a popular species in the Christmas tree industry. It is drought and heat resistant and is often used for plantings in the rural and suburb landscapes of the northern United States.

Rehabilitation: White fir is used to revegetate disturbed forest sites where it naturally occurs. It is also an appropriate choice for use on roadcuts due to its ability to stabilize soil.

Wildlife: White fir habitats are included in the summer and winter ranges of deer, elk, and bear. Mountain beaver habitat use has been correlated to white fir abundance. Many bird species, including bald eagle, northern spotted owl, brown creeper, and red-breasted nuthatches are associated with white fir habitat types.

Mule deer and black-tailed deer browse new foliage in the spring. Porcupines consume white fir bark and can destroy saplings. Mice eat snow-level suckers in the winter while pocket gophers eat seedlings in the winter and fall. Blue grouse consume the needles. Grouse, chipmunks, mice, flying squirrels, chickadees, crossbills, and Clark’s nutcracker consume white fir seeds. The Douglas squirrel caches white fir cones during late summer and fall.

Hollowed-out trunks provide protection and shelter for many small mammals including weasels, porcupines, and black bears.

Wood Products: White fir wood is used for all-purpose construction materials like framing, plywood, and pulpwood. Its straight grain makes the wood appropriate for use as poles and pilings. White fir is also used for firewood although it does not produce much heat.