I have pics of my kids on Mt. Mitchell under a canopy of fir trees at least 30 ft. tall. Green living trees.
Go up there today and all the old fir trees are gone, dead.
The Smokey Mtns. have always had a haze, I can remember back to the mid 50's. Today if you drive through the Swannanoa Valley ( I 40 east of Asheville) in July, you can't see the mountains at all. The haze is thicker than I can ever remember.
Whether the fir trees are succumbing to the pine beetle, acid rain, excess nitrogen ( all theories I've heard) the fact is something or combination of things is killing the firs on the high mountains.