Fraser fir (Abies fraseri) is the only fir species native to the southern United States, and it is found naturally only in a few stands at elevations of about 1300 m to over 2000 m in western North Carolina, eastern Tennessee, and southwestern Virginia (Dull et al., 1988). These forests are associated with important scenic and recreational areas, such as the Great Smoky Mountains National Park, Mount Mitchell State Park, the Balsam Mountains, and the Mount Rogers National Recreation Area (Dull et al., 1988). In addition to its recreational and ecological importance, Fraser fir also holds great economic importance as a Christmas tree species. It is grown in plantations as Christmas trees throughout the southern Appalachians as well as other areas of the United States. It is a premier Christmas tree species because of its aroma, blue-green color, conical shape, and excellent post-harvest foliage retention.
Natural Fraser fir populations have declined severely in the last 50 years, with most mature trees being eliminated. This decline has been due mainly to the balsam woolly adelgid (formerly balsam woolly aphid) (Adelges piceae Ratzeburg), an insect accidentally introduced from Europe. Fraser fir trees on Mount Mitchell in the southern Appalachians were found to be infested with the balsam woolly adelgid by 1957, and since then the insect has spread throughout the entire range of Fraser fir (Dull et al., 1988; Speers, 1958). Fraser fir has been shown to be one of the most susceptible of the North American fir species to balsam woolly adelgid infestation, with trees often being killed (Mitchell, 1966). By 1966, there was 95% to 98% Fraser fir mortality in the Mount Mitchell area in North Carolina (Witter and Ragenovich, 1986).
Information about the genetic variation of Fraser fir in natural stands is necessary to conserve its genetic diversity in the face of this ecological threat and to make improvements for Christmas tree production. One previous provenance–progeny test series of Fraser fir established in 1983 found significant differences among sources and among families within seed sources for all traits measured (Arnold and Jett, 1995; Arnold et al., 1994b; Jett et al., 1993). Heritabilities for most traits important in Christmas trees were strong enough to show potential for gain through selection and breeding (Arnold et al., 1994b). In 1992, following the eighth-year assessment, over 170 selections from this test series were grafted into a clone bank for advanced generation breeding and genetic conservation. In 2000, regional Christmas tree growers established a clonal seed orchard using 30 of the best selections.
The prior test series evaluated a limited number of seed sources on only three sites, so more thorough testing of a greater number of families from throughout the natural range was needed. In 1994, a more extensive seed collection was performed, where seeds from over 500 parent trees were collected from the six main populations of Fraser fir (McKeand et al., 1995). From 1997 to 2000, seedlings were grown from the seed collected in 1994 to establish a provenance–progeny test series at eight field sites in 2000. The 1983 progeny test series had not included the Grandfather Mountain seed source, and it had included trees from only one elevation class within one mountain in the Balsam Mountains source. In addition, there was a more extensive sampling of the Great Smoky Mountain seed source for this study; 10 areas were included as opposed to just one mountain in the prior study. The objectives of this study were to determine genetic variation among six seed sources of Fraser fir and to estimate genetic parameters for traits important in Christmas tree production, using data collected from this more recent provenance–progeny test series.
Arnold, R.J. & Jett, J.B. 1995 Seed source variation for growth and quality traits of Fraser fir Christmas trees: Rotation age results South. J. Appl. For. 19 4 157 161
Arnold, R.J., Bridgwater, F.E. & Jett, J.B. 1994a Single- and multiple-trait index selection efficiencies in Fraser fir Christmas trees Can. J. For. Res. 24 1487 1494
Arnold, R.J., Jett, J.B. & McKeand, S.E. 1994b Natural variation and genetic parameters in Fraser fir growth and Christmas tree traits Can. J. For. Res. 24 1480 1486
Dull, C.W., Ward, J.D., Brown, H.D., Ryan, G.W., Clerke, W.H. & Uhler, R.J. 1988 Evaluation of spruce and fir mortality in the Southern Appalachian Mountains USDA Forest Service, Southern Region, Protection Report R8-PR13 Atlanta, GA 92
Emerson, J.L., Frampton, J. & McKeand, S.E. 2006 Genetic variation of spring frost damage in three-year-old Fraser fir Christmas tree plantations HortScience 41 7 1531 1536
Jett, J.B., McKeand, S.E., Liu, Y. & Huxster, W.T. 1993 Seed source variation for height and crown traits of Fraser fir Christmas trees South. J. Appl. For. 17 1 5 9
McKeand, S., Bridgewater, F., McKinley, C., Jett, J.B. & Arnold, R. 1995 1994 seed collection from natural stands of Fraser fir and plans for breeding and genetics research at NCSU Limbs Needles 22 1 4 6–7
Mitchell, R.G. 1966 Infestation characteristics of the balsam woolly aphid in the Pacific Northwest Pacific Northwest For. and Range Expt. Sta., U.S. For. Serv 18
Witter, J.A. & Ragenovich, I.R. 1986 Regeneration of Fraser fir at Mt. Mitchell, North Carolina, after depredations by the balsam woolly adelgid For. Sci. 32 3 585 594