Exploring the Future of the Fraser Fir Industry in Western North Carolina

Abstract

Fraser fir (Abies fraseri) is the most popular species of live Christmas tree sold in the United States. It is endemic to southern Appalachia, with much of its commercial production concentrated in western North Carolina. As an agricultural commodity, the Fraser fir industry is susceptible to long-term climate trends. This thesis explores the viability of western North Carolina for growing commercial Fraser firs over the next century using climate reanalysis data and high-resolution atmospheric model projections. A suitability index was developed: the combination of vapor pressure deficit, growing degree days (Baskerville-Emin method), cold hardiness, and pH was found to be a proxy for Fraser fir potential. These variables were projected forward, and suitability recalculated with (1) no bias correction, (2) a climatological mean adjustment, or (3) a climatological mean with variance adjustment. Results agree on declined suitability across western North Carolina by 2080-2100; this finding is consistent with the hypothesis that rising temperatures will force Fraser fir production northward. Indeed, application of the suitability index to the continental USA showed a northward migration of optimal growing regions. No notable increase in precipitation during 2080-2100 relative to the historical period was identified, but current biotic threats could still be exacerbated by increased incidence of extreme rainfall events. These findings underscore the sensitivity of Fraser fir production to shifts in climate, and provide a basis for anticipating future changes in the geographic distribution of suitable regions for cultivation.