Saturday, August 25, 2007


The eastern hemlock (Tsuga canadensis) and the Carolina hemlock (Tsuga carolinana) are being poisoned wholesale in the Southern Appalachians by the toxic saliva of the woolly adelgid, an Asian bug thought to have sneaked into this country decades ago in shipments of Japanese ornamentals.

Infected hemlocks display their death sentence in cottony masses of snow-like accumulations of egg sacs on the needle-bearing branches.

The hemlocks of the Southern Appalachians constitute what are known as a "keystone species." A keystone species, by its very presence, contributes to a diversity of life. Its extinction consequently leads to the extinction of other forms of life. Keystone species help to support the entire ecosystem.

Eastern hemlocks, which are usually native to mountain stream banks where they suck up huge amounts of water, shelter and nurture many other dependent species, most especially birds and aquatic creatures. No one knows the full extent of the dominoes that will fall when the hemlocks fall.

And fall they will. Nearly all the trees along the Blue Ridge Parkway are already infested. About one-quarter of all the hemlocks in the Great Smoky Mountains National Park are already dead. Forester Tom Remaley estimates that all the untreated hemlocks in the park will be dead in two to five years.

The treatment? Expensive chemical sprays, for one. Great Smoky Mountains National Park has treated about 1,000 acres of trees in conservation areas and another 1,000 near the roadside. The Blue Ridge Parkway has treated about 2,000 trees in its forests. A drop in the proverbial bucket.

Forestry officials have also experimented with imported predatory beetles, but there are not enough beetles to make much of a dent. And the mere words "imported predatory beetles" ought to give everyone pause for the future and and law of unintended consequences.

The loss of the hemlocks may end up being a greater catastrophe than the loss of the American chestnut.

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