The following Participating Institutions are custodians for this species in the CPC National Collection:
The Morton Arboretum
San Diego Zoo Global
The conservation of Abies fraseri is fully sponsored.
Irina Kadis contributed to this Plant Profile.
The Fraser fir is endemic to high elevations in the southern Appalachian Mountains. It is named after John Fraser, the Scottish botanist/explorer who discovered it in the late 18th century. This coniferous evergreen tree grows from 30-80 ft. tall, around 12 inches in diameter, and has a narrow crown and shallow root system.
As one of the few trees to grow at high elevations, this species appears to play an important role in controlling erosion in southern watersheds by holding shallow soil to the steep wet slopes that it grows on. Unfortunately, in the past fifty years the number of mature, reproductive Fraser fir trees has declined by as much as 91% in areas where it naturally occurs. This decline is primarily attributed to the presence of an introduced insect, the balsam wooly adelgid (Dull et al. 1988), but other environmental factors, including acid rain, may also be a contributing problem.
Although the survival of this species in the wild is threatened, it is thriving in cultivation, where regular application of insecticides can control the balsam wooly adelgid. In fact, it has recently become a favorite in the Christmas tree world. The Fraser fir's natural shape, combined with its fragrant dark green foliage and long needle retention time have made it one of the most popular Christmas tree species nationwide. A 1993 report noted 2,500 North Carolina growers who planted 30,000 acres of Fraser fir, about 2,700 trees per acre. It has been recently designated 'The Cadillac of Christmas Trees' (Dirr 1998).
Distribution & Occurrence
Fraser fir is adapted to a cool, moist climate of the 'microthermal rain forest' with average annual temperatures of about 45F and annual precipitation of 75 to 100 inches that is evenly distributed during the year (Beck 1990). Fog is a very important environmental factor adding considerably to precipitation, as it is present during more than half of the growing season.
Abies fraseri most commonly grows at elevations ranging from 5,500 to 6,684 feet (1,767 to 2037 m) on shallow, rocky soil that is acidic, with a very thin black soil horizon lying directly on the bedrock.
|Populations are located in western North Carolina, eastern Tennessee, and southwestern Virginia on the peaks of the seven highest mountains in that area. These mountains include Clingman's Dome, and the Black Mountains, (including Mount Mitchell, which is the highest mountain in the eastern U.S. at 6,684ft tall) in North Carolina; Roan Mountain in Tennessee; and Mount Rogers in the Blue Ridge Mountains of southwestern Virginia.
In these populations, anywhere from 44-95% of the reproductively mature Fraser fir is dead, but a large number of fir seedlings, not yet susceptible to the damaging effects of the balsam woolly adelgid, are growing in the now-exposed understory. (Dull et al. 1988) It remains to be seen if this new generation of firs will be able to survive long enough to reach reproductive age, which is around 15 years old.
Conservation, Ecology & Research
Frampton (1998) explains the relationship among the Appalachian firs as the following:
Fraser fir is closely related to the balsam fir. The most conspicuous trait that distinguishes these two species is the relative length on the cone scales and bracts. In Fraser fir, the bracts are much longer than the cone scales and curved downward. In balsam fir the bracts are much shorter, and fully enclosed within the cone scales.
In West Virginia and the Shenandoah National Park in northern Virginia a number of isolated balsam fir have been found with cones that have a relative length of bract to scale that is intermediate between Fraser and balsam fir. Fir in these populations are called intermediate or bracted balsam fir, and designated a variety of balsam fir (Abies balsamea var. phanerolepis Fern.).
Professor Fred Hain (North Carolina State University) is trying to determine whether or not some Fraser fir are resistant to the adelgid and, if so, why. This resistance may potentially come in the form of thicker bark, or in the production of a substance called juvabione, which is similar to the adelgid's growth hormone, and keeps the adelgids from fully maturing (at least in the lab).
Professors Royce Woolsey and David Butcher (Western Carolina University) have been studying differences in the chemical composition of the seeds and foliage of Abies fraseri in an attempt to characterize the chemical differences between trees that makes some individuals or stands more resistant to attack by the balsam wooly adelgid.
Early studies of variation in morphological, anatomical and chemical characteristics revealed that Fraser, intermediate and balsam fir are all part of a cline or gradual variation pattern. Not only do bract lengths decrease and cone scale lengths increase from south to north, but a host of other traits also change along this geographic gradient. (Robinson and Thor 1969, Thor 1968, Thor and Barnett 1974, Zavarin and Snajberk 1972)
Clark et al. (2000) performed a genetic study using chloroplast microsatellites to determine if Abies fraseri is genetically distinct from the closely related taxa, Abies balsamea and Abies balsamea var. phanerolepis. Results showed a clear genetic divergence among these three eastern North American species of Fir. This study also found relatively high levels of genetic variation for all three species.
Permanent research plots were set up in a number of Fraser fir populations in the early 1960's as concern about the impacts of the balsam woolly adelgid on the species were raised. Busing and Clebsch (1988) had plots on Clingman's Dome in Great Smoky Mountains National Park, and North Carolina State University also had plots from 1966-1978.
Research on Mt. Mitchell by the University of Michigan and Forest Experimental Station found that the mortality of Fraser fir on Mt. Mitchell from 1955 to 1965 was estimated at over 1.5 million trees, which was about 82-98% of the overstory.
"Attempts to use the tree as an ornamental at low elevations have not been successful." (Harrar 1962) "Being occasionally planted in the parks and gardens of the northern states and Europe, it does not live long, suffering from hot, dry weather." (Sargent 1965) At the Arnold Arboretum in Boston, Fraser fir suffered yearly damage from the hot and dry summer conditions as well as from spider mite infestations. Despite these dire early predictions, this species is thriving in the Christmas tree trade, and a number of papers have been published on propagation methods. These studies includes propagation from seed, grafting, air layering, stem cutting, and tissue culture (micropropagation). (Bruck 1983, Wise et al. 1985, Saravitz 1990, Bryan 1991, Blazich and Hinesley 1994, Bergmann 1997, Rajbhandari and Stomp 1997, Hinesley et al. 1998, Hinesely et al. 2000)
A great deal of work has also been done in the Christmas tree industry on ways to increase the marketability of the Fraser fir as a Christmas tree. (Hinesley & Blankenship 1991a & 1991b, Hinesley et al. 1992, Hinesley & Snelling 1992, Hinesley & Snelling 1995, Hinesley & Snelling 1997, Hinesley et al. 2000)
Monitor and survey all populations: It appears as though certain stands and individual trees may have a better resistance to the balsam woolly adelgid. The location of potentially resistant trees is important in further research into resistance.
Continue research on adelgid resistance: It is important to know how and why some individual Fraser fir trees are able to combat the adelgid while others die.