Abies grandis (grand fir) description

Abies grandis

(Douglas ex D. Don) Lindley 1833

Common names

Grand, lowland, white, silver, yellow or stinking fir (Peattie 1950), sapin grandissime [French] (Hunt 1993).

Taxonomic notes

Syn: A. amabilis Murr. not Forbes, A. excelsior Franco, A. gordoniana Carr. (Vidakovic 1991), Pinus grandis Douglas ex D. Don 1832 (Hunt 1993).

This species displays some interesting morphological variation. Some authorities discriminate populations east and west of the Cascade crest as Abies grandis var. grandis and Abies grandis var. idahoensis Silba 1990 (syn.: Abies grandis subsp. idahoensis Silba 2008). The distinction between the two varieties, although not generally remarked in the American literature, has been known for a long time in Britain from provenance trials (Lines 1979), which showed that trees from coastal origins grow about twice as fast as those from interior origins, the latter being similar to A. concolor in growth rate. There are also some foliage and cone differences; var. grandis has very flat shade foliage, whereas var. idahoensis has more assurgent shade foliage (similar to that of A. concolor var. lowiana). Also, var. grandis has slightly more slender cones with thinner, less woody scales (M. Frankis e-mail 2009.07.12). The varieties do not show any significant differences in leaf essential oil composition, a finding borne out by three independent studies (Adams et al. 2015). Most modern authorities, however, find the putative differences small enough, with characters sufficiently overlapping, that the varieties are reduced to synonymy with the type.

Near its southern range limits (see range map below), A. grandis introgresses A. concolor var. lowiana; populations of such trees (A.concolor × A. grandis) are sometimes called "Abies grandicolor," though that name has not been formally described. See further notes on this phenomenon below.

Description

Trees to 75 m tall and 155 cm dbh; "crown conic, in age round topped or straggly. Bark gray, thin to thick, with age becoming brown, often with reddish periderm visible in furrows bounded by hard flat ridges. Branches spreading, drooping; twigs mostly opposite, light brown, pubescent. Buds exposed, purple, green, or brown, globose, small to moderately large, resinous, apex round; basal scales short, broad, equilaterally triangular, slightly pubescent or glabrous, resinous, margins entire, apex pointed or slightly rounded. Leaves (1)2-6 cm × 1.5-2.5 mm, 2-ranked, flexible, with leaves at center of branch segment longer than those near ends, or with distinct long and short leaves intermixed, proximal portion ± straight, leaves higher in tree spiraled and 1-ranked; cross section flat, grooved adaxially; odor pungent, faintly turpentinelike; abaxial surface with 5-7 stomatal rows on each side of midrib; adaxial surface light to dark lustrous green, lacking stomates or with a few stomates toward leaf apex; apex distinctly notched (rarely rounded); resin canals small, near margins and abaxial epidermal layer. Pollen cones at pollination bluish red, purple, orange, yellow, or ± green. Seed cones cylindric, (5)6-7(12) × 3-3.5 cm, light green, dark blue, deep purple, or gray, sessile, apex rounded; scales ca. 2-2.5 × 2-2.5 cm, densely pubescent; bracts included. Seeds 6-8 × 3-4 mm, body tan; wing about 1.5 times as long as body, tan with rosy tinge; cotyledons (4)5-6(7). 2n=24" (Hunt 1993).

The essential differences between A. grandis and A. concolor, which serve to identify introgressed populations, concern stomata and the "sawtooth". A. grandis contains no or very few and distal stomata on the adaxial (upper) leaf surface, while A. concolor has abundant stomata that nearly cover the adaxial leaf surface. Intermediate conditions identify hybrids; Zobel (1973) found that "either 'maximum number of adaxial stomatal rows' or 'percentage of length of needle with adaxial stomata' can be used to describe the extent of adaxial stomata." The "sawtooth" refers to the strong tendency in A. grandis for needles along one side of the twig to alternate in length, short to long to short, as shown in the photos at right. This phenomenon is uncommon in A. concolor. Zobel (1973) also notes a variation in leaf apex, from distinctly notched in A. grandis to obtuse or shallowly notched in A. concolor. The "sawtooth" sometimes also occurs in A. amabilis, which may occur near A. grandis in some areas such as the northern Olympic peninsula; however A. amabilis also has some needles dorsal to the twig, which is never seen in A. grandis.

Distribution and Ecology

Canada: British Columbia; USA: Montana, Idaho, Washington, Oregon and California at 0-1500 m in moist conifer forests (Hunt 1993). Hardy to Zone 6 (cold hardiness limit between -23.2°C and -17.8°C) (Bannister and Neuner 2001). See also Thompson et al. (1999).

Distribution of Abies concolor var. concolor (blue), A. concolor var. lowiana (red), A. grandis (orange), and A. grandis x concolor hybrids (purple). Data downloaded 2020.11.13 from GBIF and the Consortium of Pacific Northwest Herbaria; see description in map (click on tray icon) for further detail; click on points for further data.

Within the zone of introgression to A. concolor, individual populations may contain trees displaying characters ranging from very good coastal A. grandis to Sierra Nevada-typical A. concolor var. lowiana. Zobel (1973) studied a gradient of hybrid populations from true A. grandis to nearly true A. concolor and found that "low-elevation populations west of the Cascade crest, mostly on river terraces, resemble A grandis. High-elevation west-side populations, disjunct from those at low elevations and occupying ridge tops and steep, dry slopes, include trees with some traits of A. concolor. Populations on the east flank of the Cascades show a greater but widely variable influence of A. concolor. East-side populations vary locally with aspect, being most like A. grandis on north slopes, but they do not clearly vary with elevation. Incidence of characteristics resembling A. concolor increases from north to south." Ott et al. (2015) showed that the hybrid populations occupy a distinctly different ecological niche than either A. grandis or A. concolor, identifying two distinct hybrid classes that "occupy distinct habitats that are variably intermediate between those associated with A. grandis and A. concolor for a majority of environmental variables, but with lower precipitation in the summertime in the southern Cascade, Siskiyou, and Sierra Nevada Mountains than associated with either progenitor. We hypothesize that moisture stress and high levels of solar insolation in the summertime associated with hybrid populations have played an important role in the observed patterns of introgression of key traits: leaf angle, specific leaf area, and abundance of adaxial stomates." This is consistent with the finding by Zobel (1974) that hybrid populations of the eastern Cascades experience lower summer moisture stress than A. grandis of the western Cascades, despite occurring on sites with more xeric vegetation and lower summer precipitation. Ott et al. (2015) conclude that "in the context of moisture stress associated with predicted climate change, hybrids may have an adaptive advantage over A. grandis."

Grand fir and its hybrid with A. concolor are occasionally afflicted by the dwarf mistletoe Arceuthobium abietinum subsp. grandae (Kenaley 2020). Other pests known to afflict grand fir include the balsam woolly adelgid, fir engraver beetle, western balsam bark beetle, hemlock looper, spruce budworm, spruce spider mites, fir seed chalcid, obtuse sawyer, and Douglas-fir tussock moth; while common fungal pathogens include Armillaria root rot and laminated root rot. The adelgid is particularly pernicious, as it is a species introduced from Europe in about 1900 that caused locally heavy mortality of Abies amabilis, A. grandis, and A. lasiocarpa during the late 1950’s and 1960’s, with ongoing occasional local recurrence of infestations (U.S. Forest Service 2017a). The fir engraver and western balsam beetles are bark beetles that can, during outbreaks, cause locally heavy mortality. The hemlock looper, a defoliator, is similarly destructive, as is the spruce budworm, which defoliates by consuming new foliage (Gardenia 2024). Armillaria root rot is widespread and persistent, a major cause of chronic mortality among Abies and Pseudotsuga of western North America, but due to local distribution and slow action, most forests in the area suffer only limited effects (U.S. Forest Service 2017b). Conversely, laminated root rot (Phellinus sulphurascens) is the most destructive root disease afflicting Abies, Pseudotsuga, and Tsuga mertensiana in the Pacific Northwest, greatly reducing root strength and contributing to windbreak and windfall. It is a particular concern in populated areas because affected trees typically show no evidence of decline before they fall, and thus pose risks to life and property (U.S. Forest Service n.d.).

Remarkable Specimens

Since 1988, the largest known specimen has been a tree called the Barnes Creek Survivor near Lake Crescent Lodge in Olympic National Park, Washington. At the 2023 remeasurement it was 217.5 cm dbh and 69.6 m tall, with a 14.6 m crown spread and a stem volume of 81.7 m³, which also makes it the largest grand fir on record. It has grown 22% in volume since 1992 and remains a very healthy tree. The tree got its name because it was slated to be removed when Highway 101 was relocated in 1979. A bulldozer operator thought it was a significant tree and the Park decided to save it. It still grows conspicuously close to the highway (Van Pelt email 2024.11.17).

Largest recorded diameter: the "Chilliwack Giant", height 75.0 m, dbh 220 cm, stem volume 78.4 m³; alive in 2001, it has since died (Van Pelt emails 1998.03.18 and 2024.11.17).

Tallest: Height 81.4 m, dbh 158 cm, stem volume 53.0 m³ in 1993; in the Glacier Peak Wilderness, WA (Van Pelt 1996).

Largest ornamental specimen: planted in 1875, a tree 209.1 cm dbh and 63.4 m tall (in 2019), at the Ardkinglas Arboretum in Scotland. It is the only planted tree that has grown large enough to rival the largest trees in habitat (Van Pelt email 2024.11.18).

The tallest tree in Norway is a grand fir that was 53.7 m tall when measured in 2022 (Monumental Trees 2022).

The oldest tree was reported by Aho (1977), who cited a ring count of 472, of which 163 rings were in the first 7.6 cm of the sample (the tree was 87.6 cm DBH and 33.5 m tall). This indicates that the tree attained an impressive age because it spent a long time as a small suppressed advance regeneration tree in the forest understory. Similar ecological settings have been observed among the oldest individuals of Abies amabilis and Abies lasiocarpa, as well as in various species of Picea and Tsuga.

Ethnobotany

Due to very rapid growth, this is an important species for production of pulpwood, although due to low strength it is not a preferred timber species. In some areas, particularly within its native range, it is widely grown as a Christmas tree, although the related Abies procera is generally seen as more attractive and commands higher prices. In areas of suitable climate, particularly in Europe, it is also a popular species in the larger parks and gardens, and a wide variety of ornamental cultivars are available (Farjon 2010).

Observations

In western Washington and western Oregon, the coastal form of the species is relatively uncommon. Some fine examples can be found along the south shore of Lake Crescent in Olympic National Park; the largest specimen of the species was formerly found here (felled by a severe storm). As noted above (Big trees), some exceptional trees can also be found along the Duckabush River in the eastern Olympics, along the Chilliwack River in British Columbia, and in the Glacier Peak Wilderness.

Var. idahoensis is exceedingly common in riparian settings along streams and rivers within its range. It typically occurs at fairly low elevations, in the company of Pinus ponderosa and Pseudotsuga menziesii var. glauca, and with increasing elevations commonly surrenders to competition with Picea engelmannii. Probably the finest stand I have seen is along White Pine Creek in Washington's Chiwaukum Mountains (47.756°N, 120.941°W), where a portion of the valley is filled by an old growth Abies grandis stand with many trees over a meter in diameter. As the name suggests, it is also a great place to see big Pinus monticola.

Abies grandis × concolor is quite common in the Klamath Mountains along the road from Happy Camp, California to Cave Junction, Oregon. Look for it at elevations above 1000m while still south of the California-Oregon border. This is also a very good place to see Picea breweriana, as well as a host of other conifers including Abies magnifica × procera, Pinus attenuata, Pinus lambertiana, Pinus jeffreyi, Pseudotsuga menziesii, Calocedrus decurrens, Chamaecyparis lawsoniana, and a shrubby form of Taxus brevifolia.

Remarks

This is another of the many North American conifers first described by David Douglas. See the Topics page for more on Douglas.

Citations

Adams, Robert P., Michael Kauffmann, and Frank Callahan. 2015. The leaf essential oil of Abies grandis (Doug. ex D. Don) Lindl. (Pinaceae): revisited 38 years later. Phytologia 97(1):1-3.

Aho, P. E. 1977. Decay of grand fir. USDA Forest Service Research Paper PNW-229. Portland, OR: Pacific Northwest Forest and Range Experiment Station. 18 p.

Gardenia. 2024. https://www.gardenia.net/guide/abies-fir-pests-and-diseases, accessed 2024.11.20.

Kenaley, Shawn C. 2020. New subspecies of fir dwarf mistletoe (Arceuthobium abietinum: Viscaceae) from the western United States and northern Mexico. Journal of the Botanical Research Institute of Texas 14(1):27–45. DOI: https://doi.org/10.17348/jbrit.v14.i1.894.

Lines, R. 1979. Natural variation within and between the silver firs. Scottish Forestry 33(2):89-101.

Ott, T., E. Strand, and C. Anderson. 2015. Niche divergence of Abies grandis–Abies concolor hybrids. Plant Ecology 216:479–490.

U.S. Forest Service. [undated]. What is laminated root rot disease? https://www.fs.usda.gov/detailfull/ochoco/home/?cid=FSEPRD581546, accessed 2024.11.20.

U.S. Forest Service. 2017a. Balsam wooly adelgid. https://apps.fs.usda.gov/r6_decaid/views/balsam_woolly_adelgid.html, accessed 2024.11.20.

U.S. Forest Service. 2017b. Armillaria root disease. https://apps.fs.usda.gov/r6_decaid/views/armillaria_root_disease.html, accessed 2024.11.20.

Zobel, D. B. 1973. Local variation in intergrading Abies grandis-Abies concolor populations in the Central Oregon Cascades: Needle morphology and periderm color. Botanical Gazette 134(3):209–220.

Zobel, D. B. 1974. Local variation in intergrading Abies grandis-Abies concolor populations in the Central Oregon Cascades: II. Stomatal reaction to moisture stress. Botanical Gazette 135(3):200–210.