A Comparison of Virgin Spruce‐Fir Forest in the Northern and Southern Appalachian System

Forest Response to the US 1990 Clean Air Act: The Southern Spruce-Fir Ecosystem

“…Based on the trend since 2002, LSD is predicted to continue to decrease over time. LSD is predicted to reach previously recorded, and assumed normal levels indicated by Oosting and Billings [1] within the next couple of decades. If these trends continue, a reduction in LSD will subsequently increase the amounts of DSD and coarse woody material on the forest floor.…”

“…The forest has not yet reached previous live stem density levels recorded before BWA induced declines, but are close to approximately normal pre-disturbance levels of live basal area. It is predicted that within the next 40 -60 years, given no BWA reoccurrence or other disturbance, the Spruce-Fir forest in the Black Mountains will resemble the forest as observed by Oosting and Billings [1] in 1946. If BWA resurgence or other disturbance were to occur, the forest community at Mt.…”

“…The Southern Appalachian Mountains of North Carolina, Virginia, and Tennessee house a unique and rare forest ecosystem type known as the Appalachian Spruce-Fir [1]. Canopy dominating tree species in these forests include the red spruce (Picearubens Sargent) and the endemic Fraser fir (Abiesfraseri [Pursh] Poiret).…”

“…Canopy dominating tree species in these forests include the red spruce (Picearubens Sargent) and the endemic Fraser fir (Abiesfraseri [Pursh] Poiret). These historical forest ecosystems are remnants of the Pleistocene epoch in an era when the northern reaches of the forests were affixed to the Appalachian southern reaches [1][2][3]. Despite similar appearance and floristic continuity [4] to boreal spruce-fir forests extending from Alaska into eastern Canada, these southern montane spruce-fir forests differ in many aspects.…”

“…The endemic Fraser fir, Abiesfraseri, exists only in the southern Appalachian ranges, as opposed to Balsam fir, Abiesbalsamea, in the boreal reaches [5]. Additionally, a deciduous shrub understory consisting of Rhododendron catawbiense exists in the Appalachian spruce-fir forest [1,6], whereas boreal forests are essentially one-storied with few shrub species [7].…”