Abies procera

Noble fir

Pinaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Coniferophyta (conifers). Class - Pinopsida. Order - Pinales. Family - Pinaceae (pine). Genus -Abies Mill. Species - Abies procera Rehder

Ecology: Noble fir is a native, long-lived conifer. Noble fir is a seral or pioneer species. Noble fir often establishes with Douglas-fir. It establishes after disturbances such as wildfire that create major stand openings. Noble fir is eventually replaced by shade-tolerant species such as Pacific silver fir and western hemlock. Noble fir occurs in a maritime climate with cool summers and mild, wet winters. Annual precipitation is between 72 and 106 inches (1,960-2,650 mm). Most of the precipitation occurs between October and March, resulting in snowpacks of 3 to 10 feet (1-3 m). The growing season in the Pacific silver fir zone averages 40 to 50 days. Noble fir grows well on a variety of sites. It occurs on steep slopes but grows best on gentle slopes and warm southern aspects. Shallow or moderately deep loams support good growth. Inceptisols and Spodosols are common. Soils are typically developed in volcanic parent materials.

Identification

Trees to 80m; trunk to 2.2m diam.; crown spirelike. Bark grayish brown, in age becoming thick and deeply furrowed (furrows and ridges about same width) and reddish brown (especially reddish when plates flake off). Branches diverging from trunk at right angles, stiff; twigs reddish brown, finely pubescent for several years. Buds hidden by leaves, tan, ovoid, small, not resinous, apex rounded; basal scales short, broad, equilaterally triangular, pubescent centrally, not resinous, margins entire to crenate, apex sharp-pointed. Leaves 1--3(--3.5)cm 1.5--2mm, 1-ranked, flexible, proximal portion often appressed to twig for 2--3mm (best seen on abaxial surface of twig), distal portion divergent; cross section flat, with prominent raised midrib abaxially, with or without groove adaxially, or cross section 4-sided on fertile branches; odor pungent, faintly turpentinelike; abaxial surface with 2--4 glaucous bands, each band with (4--)6--7 stomatal rows; adaxial surface bluish green, with 0--2 glaucous bands, each band with 0--7 stomatal rows at midleaf; apex rounded to notched; leaves on fertile branches 4-sided with 4 bands of stomates below; resin canals small, near margins and abaxial epidermal layer. Pollen cones at pollination purple, red, or reddish brown. Seed cones oblong-cylindric, 10--15 5--6.5cm, green, red, or purple, overlaid with green bracts, at maturity brown (bracts light-colored and scales dark), sessile, apex rounded; scales ca. 2.5 3cm, pubescent; bracts exserted and reflexed over scales. Seeds 12 6mm, body reddish brown; wing slightly longer than body, light brown to straw; cotyledons (4--)5--6(--7). 2 n =24.

Threats

In the WFDP: Noble fir is rare in the WFDP, with only fifteen trees above 1 cm at DBH that are tagged. Suppression is the likely cause of mortality of noble fir in this energy-limited system. Noble fir is the most shade intolerant of the American true firs and cannot regenerate under a closed forest canopy.

Fire effects: The bark of young noble fir is relatively thin, making them sensitive to fire at this growth stage. Fire resistance of larger, thicker barked trees is reported to be low to moderate. The foliage of noble fir is moderately to highly flammable. Noble fir self-prunes well in closed, dense stands, which reduces fuel ladders and, thus, fire spread to the canopy. Stands dominated by noble fir have the smallest quantites of forest floor material (compared with stands dominated by other western conifers that occur in its range), and accumulation of fuel is low. After stand-destroying fires, noble fir and Douglas-fir are initial colonizers.

Pests and pathogens: Insects reported as attacking noble fir include two bark beetles (Pseudohylesinus nobilis and P. dispar); a weevil, Pissodes dubious, sometimes in association with the fir root bark beetle, Pseudohylesinus granulatus; and a large root aphid, Prociphilus americanus.

Reproduction

Flowering and Fruiting -Like other true firs, noble fir is monoecious and produces female strobili high in the crown and clusters of male strobili in a zone below.

Seed Production and Dissemination -Trees may begin bearing cones at 20 years of age, although commercial seed bearing is generally considered to begin at about 50 years. Seed quality is typically poor. Collections from seed traps in natural stands (equivalent to 54 seed years) had a maximum of 49 percent sound seeds; the overall average was about 10 percent. Noble fir seeds are not widely dispersed because of their weight, which averages 29,750 seeds per kilogram. Wind is the major agent of dispersal, but most seeds actually fall within one or two tree heights of the seed trees.

Seedling Development - Noble fir seeds are of transient viability under natural conditions, and most germinate in the first growing season after dispersal. They remain viable for only one season in the forest floor. Seed dispersed after snow covers the ground may germinate in and on the snowbanks the next spring, with essentially no chance for survival of such germinants. Initial growth of noble fir is typically slower than that of associated species.

Vegetative Reproduction - Noble fir is not known to reproduce vegetatively.

Species Distribution

Citation

Silvics of North America
Burns, R.M., and B.H. Honkala. 1990. Silvics of North America (Volume 1: Conifers, Volume 2: Hardwoods). USDA Forest Service Agricultural Handbook 654.

USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

USFS Plant Database
Habeck, R. J. 1992. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

Burke Museum of Natural History and Culture
Burke Museum. 2016. Abies procera [Online]. University of Washington.
Photo credit: Ben Legler 2012