Assessing the Impacts of Balsam Woolly Adelgid (Adelges piceae Ratz.) and Anthropogenic Disturbance on the Stand Structure and Mortality of Fraser Fir [Abies fraseri (Pursh) Poir.] in the Black Mountains, North Carolina

Over the past several decades, naturally occurring populations of Fraser fir (Abies fraseri) in the Black Mountains of North Carolina have been heavily impacted by both direct and indirect anthropogenic disturbances, including logging and logging-associated fires, and high mortality rates due to the balsam woolly adelgid (Adelges piceae) (BWA). The decline in Fraser fir is worrisome because it serves as a foundation species of the spruce-fir forests of the Southern Appalachian Mountains. Our objectives for this research were to: 1) characterize the current status of Fraser fir trees with respect to potential population decline, as identified by the regeneration-mortality hypothesis, by using stand structure and infestation levels, 2) determine the influence of slope, elevation, aspect, and disturbance history on stand structure, mortality, and BWA infestation level, and 3) examine broad trends of Fraser fir cover change caused by BWA over a 60 year period by using repeat aerial photography. We conducted detailed field surveys of Fraser fir trees throughout the Black Mountains using 44 circular plots. Analysis of repeat aerial and ground photographs revealed a decline in Fraser fir cover >60% from 1954 to 1988, followed by regeneration from 1988 to 2006. Our results indicate that Fraser fir stands at higher elevations are currently in a state of recovery, whereas Fraser fir stands at lower elevations have the potential to become increasingly susceptible to BWA-induced mortality in the future. Our results call attention to the significant impact of direct and indirect anthropogenic disturbance upon Fraser fir stand structure, but also provide evidence for the ability of an imperiled ecosystem to recover from such activity.