Abies grandis

Grand 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 grandis (Douglas ex D. Don) Lindl.

Ecology: Grand fir occurs in the overstory of both seral and late-successional forests. It is climax throughout the grand fir series and is a major seral species in some western redcedar, western hemlock, subalpine fir, and Pacific silver fir habitat types. It exhibits moderate growth in the open, yet is shade-tolerant enough to establish and grow beneath an open forest canopy. Grand fir is not as shade-tolerant as western redcedar, hemlocks, or other firs and does not establish beneath a closed canopy. Grand fir does not require disturbance to establish and persist on most sites; however, where western hemlock or western redcedar is the climax dominant, fire or other periodic disturbance is needed to maintain grand fir. Grand fir may colonize a site soon after fire or other stand-replacing disturbance. Grand fir hybridizes with white fir (A. concolor). A broad zone of intergraded grand white fir populations occurs from northeastern Washington and Oregon south to northern California and east to west-central Idaho.

Identification

Trees to 75m; trunk to 1.55m diam.; 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--6cm l.5--2.5mm, 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--3.5cm, light green, dark blue, deep purple, or gray, sessile, apex rounded; scales ca. 2--2.5 2--2.5cm, densely pubescent; bracts included. Seeds 6--8 3--4mm, body tan; wing about 1.5 times as long as body, tan with rosy tinge; cotyledons (4--)5--6(--7). 2 n =24.

Threats

In the WFDP: The primary mortality agent of grand fir in the WFDP is Armillaria root rot (aka Honey fungus; Armillaria spp.). Grand fir is also susceptible to supression in this energy-limited system.

Fire effects: Young grand fir have thin bark and are easily killed by fire. The bark thickens as trees age, and mature trees are moderately resistant to fire. Ground fires burning into the duff injure shallow roots and may kill even mature trees. Grand fir regeneration is common after fire. Seedlings establish on burns mostly from off-site seed sources. Mature grand fir that survive a fire provide an on-site seed source. Fire provides a favorable seedbed. Several morphological characteristics of grand fir lend to its relative flammability. Branching habit is low and dense; stands tend to be dense as well. The foliage has a higher surface-to-volume ratio than that of associated conifers, and the needles are retained longer on the tree.

Pests and pathogens: The western balsam bark beetle (Dryocoetes confusus) and the fir engraver (Scolytus ventralis) are the principal bark beetles attacking grand fir. Susceptibility to heart rot and decay is one of the more important factors in the management of grand fir. Armillaria spp.and Phellinus weirii are the two most important root rot fungi. Indian paint fungus (Echinodontium tinctorium) is the most destructive fungus in forests east of the Cascade crest.

Reproduction

Flowering and Fruiting - Grand fir trees are monoecious; male and female flowers are borne in clusters on branchlets of the previous season's growth in different parts of the same tree. Female flowers, producing cones and seeds, are short, spherical to cylindrical, and stand singly and erect on the uppermost part of the crown. Male flowers, pollen-bearing only, are ovoid or cylindrical and hang singly from the lower side of branches below the female flowers.

Seed Production and Dissemination -Seed production begins at about 20 years of age and increases with age, diameter, and vigor of the tree. When the cones are ripe, the scales fall away and release the large-winged seeds, leaving only the central spike. Seeds are dispersed by the wind and rodents.

Seedling Development - Grand fir seeds germinate in the spring following one overwinter period on the ground. In natural stands, germination is quite variable but is seldom greater than 50 percent because of embryo dormancy, insect infestation, and the perishable nature of the seeds. Seeds are often so heavily infested with insects that an entire crop may be classed as a failure.

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 grandis [Online]. University of Washington.