The southern most spruce
species in eastern North America is red spruce, Picea rubens, although eastern hemlock, Tsuga canadensis, is sometimes called a
spruce.A few other spruces are planted
with Colorada blue spruce, P. pungens,
being the most popular.In a recent trip
to Philmont Scout Ranch in New Mexico one of the most impressive trees was
Engelmann spruce, P. engelmannii,
where a couple of specimens at the Clear Creek homestead are about 400 to 500
years old.The dieback of large tracts
of red spruce in the GreatSmokyMountainNational Park is often
claimed to be evidence of acid rain pollution, but the places were it seems that the
whole forest dies is where there had been a clearcut nearly a hundred years
before.The resulting even age forest is
then more susceptible to epidemic disease especially when they reach a reach an
age close to the normal lifespan.In
virgin spruce-fir forest there are examples of bands of even aged trees that
give the mountains a brindled appearance.These bands propagate through the forsest as the lifespan of the trees progress only to be replaced by seedlings after the older trees die.This replacement of dead trees with seedling can easily be seen in the
middle of the Great at SmokyMountains at Clingman’s
Dome where there are even a few remaining middle aged trees that are growing in areas
that were disturbed since the forest in that area was clearcut.The pattern of the spruce trees dieing in the
Great Smoky Mountains is probably following in
the same order that portions of the forest had been clearcut.If pollution such as acid rain had been the
real cause then all the trees everywhere would die especially the seedlings,
which would likely be more vulnerable to such an environmental stress.With all the dead trees in those areas of the
forest there is now more habitat for salamanders, which reach their highest
diversity of anywhere in the world in the Smoky Mountains, beside the national park alone reportedly
having more floral diversity than the entire continent of Europe.
