Abies magnifica

Red 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 (pines). Genus - Abies Mill. Species - Abies magnifica A. Murray bis

Abies magnifica often exists in extensive high elevation stands in the Sierra Nevada; its close relative A . procera occurs in small mountaintop populations relatively isolated from one another. As expected for isolated populations, A . procera produces large interpopulation variation in morphology (J.Maze and W.H. Parker 1983) and chemistry (E.Zavarin et al. 1978). Where the two species meet in southern Oregon and northern California, many populations are intermediate; these have been called A . magnifica var. shastensis Lemmon. The status of such intermediates is unsettled. They may be accepted as hybrids between A . magnifica and A . procera (Liu T. S. 1971) or, alternatively, the paleontological record suggests that the two species may have originated from the intermediates (E.Zavarin et al. 1978). Individuals from this region should be assigned to A . magnifica , A . procera , or A . magnifica procera (E.L. Parker 1963), depending on the morphologic criteria selected to differentiate the species, though clearly these individuals are genetically quite different from those near the type localities of the two species. California red fir hybridizes with noble fir (A. procera) where they occur together. These hybrids are similar to Shasta red fir, which increases taxonomic confusion of the California red fir-noble fir complex in the Klamath region. Morphological comparisions, artifical crosses, and molecular studies indicate that Shasta red fir resulted from California red fir and noble fir introgression.

Ecology: California red fir occurs in pure, dense forests between the lower montane white fir (Abies concolor) or mixed-conifer forests and the upper montane or subalpine lodgepole pine (Pinus contorta var. murrayana) and mountain hemlock (Tsuga mertensiana) forests. In the upper montane coniferous forests, California red fir is an overstory dominant on mesic sites. Canopies can be open or closed, and understory vegetation is variable but generally sparse.

Identification

Trees to 57m; trunk to 2.5m diam.; crown narrowly conic. Bark grayish, thin, with age thickening and becoming deeply furrowed with ridges being often 4 times wider than furrows, plates reddish. Branches ascending in upper crown, descending in lower crown; twigs opposite to whorled, light yellow to tan, reddish pubescent for 1--2 years. Buds hidden by leaves or exposed, usually dark brown, ovoid, small, not resinous or with resin drop near tip, apex rounded; basal scales short, broad, equilaterally triangular, densely pubescent, not resinous, margins entire to crenate, apex sharp-pointed. Leaves 2--3.7cm 2mm, mostly 1-ranked, flexible, the proximal portion often appressed to twig for 2--3mm (best seen on abaxial surface of twig), distal portion divergent; cross section flat, with or without weak groove adaxially toward leaf base, or cross section 3--4-sided on fertile branches; odor camphorlike; abaxial surface with 2 glaucous bands, each band with 4--5 stomatal rows; adaxial surface blue-green to silvery blue, with single glaucous band that may divide into 2 toward leaf base, band with (8--)10(--13) stomatal rows at midleaf; apex rounded or, on fertile branches, somewhat pointed; resin canals small, near margins and abaxial epidermal layer. Pollen cones at pollination purple or reddish brown. Seed cones oblong-cylindric, 15--20 7--10cm, purple at first but becoming yellowish brown or greenish brown, sessile, apex round; scales ca. 3 4cm, pubescent; bracts included to exserted and reflexed (Shasta red fir) over scales. Seeds 15 6mm, body dark reddish brown; wing about as long as body, rose; cotyledons 7--8.

Threats

Fire effects: Fires in high-elevation California red fir forests are generally not as intense as those in the Rocky Mountains and are typically less intense than those at lower elevations. This may be a result of low annual fuel accumulation because of the short growing season. Fire has an important role in Sierra Nevada conifer forests, particularly in the successional relationship between California red fir and lodgepole pine. Fire creates canopy openings by killing mature lodgepole pine and some mature California red fir. The bark of older California red fir is thick and fire resistant. The needles and branch tips are resistant to fire. Seedlings of California red fir are easily killed by fire. Seedlings and saplings are killed by relatively low-intensity fires, but few older California red fir are affected. Larger California red fir are killed by severe fires.

Pests and pathogens: Red fir dwarf mistletoe (Arceuthobium abietinum subsp. magnificae) is common throughout the range of red fir and infests 40 percent of the stands in California. Heavily infected trees suffer significant growth losses and are subject to attack by Cytospora abietis, a fungus that kills branches infected by dwarf mistletoe and further reduces growth. Because of reduced vigor, infected trees are more susceptible to bark beetle attack and other diseases. Heart rots, entering through open mistletoe stem cankers, increase volume loss directly and mortality indirectly through stem breakage. The most severely damaging insect pest on red fir is the fir engraver (Scolytus ventralis). This bark beetle is found throughout the range of red fir and causes severe damage nearly everywhere. Losses under epidemic conditions can be dramatic. Anything that reduces tree vigor - Annosus root disease, dwarf mistletoe, Cytospora canker, overstocking, drought, or fire damage - increases susceptibility to fir engraver attack.

Other: Red fir appears to be more sensitive to drought than white fir or the associated pines, even though over most of its range there may be no precipitation for as long as 5 months during the summer. A tendency of red fir to grow poorly where snowmelt water collects, as on mountain meadows, indicates a moderate sensitivity to high soil moisture content during the growing season. Because cones are borne almost exclusively in the uppermost 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.

Reproduction

Flowering and Fruiting - Red fir is monoecious. Male strobili (cones) are small-generally less than 1.6 cm long-deep purple-red, and densely clustered on the underside of 1-year-old twigs about midcrown. Female cones are borne erect on 1-year-old branches in the uppermost crown, although both male and female cones are occasionally found on the same branch. Cones are large, 15 to 23 cm long, 5 to 8 cm in diameter, and oblong cylindric in shape. Shasta red fir bracts are longer than the cone scales and are easily visible on the surface of a mature cone. California red fir bracts are shorter than the cone scales and are not visible on an intact cone.

Seedling Development - Red fir seeds germinate in the spring immediately after snowmelt or in, on, and under the snow. Germination is epigeal. Seeds that germinate several centimeters above ground in the snowpack rarely survive. Seeds that fall before the first permanent snows of winter, therefore, are more effective in producing seedlings.

Vegetative Reproduction - Under natural conditions red fir does not reproduce vegetatively either by sprouting or layering. Trees which have lost their tops, however, can frequently develop new terminals and resume cone bearing.

Species Distribution

Citation

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.

The Jepson Herbarium
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA.

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.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97. Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.