One of my favorite places is a dense stand of hemlocks along Indian Fork Creek near the Brimstone community.
There, along property managed by Brimstone Recreation, hemlocks crowd along the creek and hover over the road, creating a shady spot that remains cool on even the hottest days of summer. A nearby waterfall is a popular destination for ATV riders on the property. The cool, shaded creek bottom is in many ways its own little world in a vast forest that is made up of clear cuts of varying ages in any direction.
Unfortunately, this hemlock forest — like many along the Cumberland Plateau — is dying. The tell-tale tufts of cottony-like material cling to the underside of the hemlocks’ flat needles along the creek and the small branches that feed into the creek up and down Indian Fork Creek Valley. Some of the most infected trees are already losing foliage and showing early signs of dying back.
It isn’t a problem specific to Indian Fork Creek, nor even the plateau. The cause is the hemlock woolly adelgid, a tiny pest that has been battled by the Great Smoky Mountains National Park for more than a decade. More recently, the Big South Fork National River & Recreation Area and Obed Wild & Scenic River took up the fight as well, as the HWA spread west to the plateau.
In the years to come, most of the hemlocks in the region will die. Only those protected by pesticides will survive. In the Big South Fork, where hemlock stands are more numerous than most other parts of the plateau and where some of the most intense hemlock preservation attempts are being undertaken, more than 80 percent of the hemlocks are expected to die in the coming years.
Researchers at the University of Tennessee are intensely studying methods of controlling the HWA. Their efforts include the aerial application of pesticides and introduction of a separate type of insect that voraciously feeds on the HWA. Both have shown modest success. But a variety of factors, not the least of which are time and money, are likely to spell doom for widespread success before the hemlock’s native range is drastically reduced in the southern Appalachians.
The HWA has one major connection to the fungus that wiped out eastern America’s stately chestnut trees in the early 1900s — its origin.
The woolly adelgid and the fungus responsible for the chestnut blight each originated in Asia. The chestnut fungus was imported to America from Japan as part of a shipment of chestnut nursery stock in 1900, while the HWA was imported to North America from east Asia just 24 years later.
The chestnut blight quickly wiped out the prevalent American chestnut, doing most of its damage by 1940. The HWA has taken considerably longer to manifest itself in the same region, but now that it has, its woodland slaughter is occurring at no less a rapid pace than the chestnut blight set a century ago.
Today, most of us can only imagine what the forests here along the Cumberland Plateau once looked like when the chestnuts were the dominant tree. A few remnants remain; young chestnuts still sprout from old roots, only to die off before they reach maturity, and they are sometimes seen in the forests. Occasionally, a decaying chestnut log can still be found from where it crashed in the forest long ago. Local church pastor Dudley Harness, for example, knows the location of a massive chestnut trunk east of Huntsville.
Years from now, our grandchildren and great-grandchildren may very well only be able to imagine what these forests once looked like with their dense hemlock stands. The hemlock isn’t going the way of the American chestnut, of course; botany studies have come a long way over the past 100 years and efforts are being taken to preserve important stands of the tree, insuring that there will be hemlocks in both the Big South Fork and the Smokies for years to come. Landowners also have options available to save the hemlocks around their home or on their property, something that was not available when the chestnut blight was sweeping through the region in the early 20th Century. Still, the forests here are likely to be significantly altered by the HWA, just as they were significantly altered by the chestnut blight.
Even as the HWA is manifesting itself here at home, another invasive pest is wreaking havoc in the forests across the region. The Emerald Ash Borer — which, like the HWA and the chestnut fungus, was accidentally imported from Asia — is the cause for a quarantine on all firewood in most of East Tennessee, including Anderson and Campbell counties but not Scott or Morgan counties.
Introduced in the late 1990s and originally detected in Michigan, the EAB has already killed an estimated 100 million ash trees and is expected to wipe out most of the 7.5 billion ash trees in North America. Damage estimates run in the billions of dollars.
The Asian long-horned beetle, first discovered in 1996, has not yet made it to Tennessee but has been discovered as nearby as Ohio. It infests and destroys several varieties of trees, including maple, willow and elm.
A species of ambrosia beetle accidentally imported from Asia is devastating the Deep South’s red bay trees, particularly in Georgia, where red bays — often used for firewood and outdoor grilling — have been dying since 2003.
In California, forestry officials are battling what they call “sudden oak death.” Just as its name suggests, the fungal infestation is wiping out populations of California black oak and other species in the California coastal region. The origin of the fungus isn’t clear, but is believed to be Asia.
Most of these pests were accidentally imported to North America as part of wood packaging used in the shipping process, researchers say. And, they say, the pests currently present won’t be the last.
“Entire forests are being wiped out, and it is costing taxpayers millions as the government tries to eradicate invaders that threaten industries dependent on trees and plants,” University of Central Florida biologist Besty Von Holle told Science Daily recently. “We’re losing a variety of native species as a result of importing these pests. It’s not just aesthetics. It’s impacting our economy.”
Von Holle was part of a project that estimated that there are currently 455 insects and 16 pathogens wiping out American forests, and that a major destructive pest will sneak into the U.S. every two years based on the current pattern.
Of course, not all the pests are foreign. Some homegrown pests have caused — and are causing — substantial damage. The southern pine beetle, which devastated the Cumberland Plateau’s southern pine stands a decade ago, is native to the U.S., as is the twig beetle that causes thousand canker disease.
The disease is currently causing serious problems for East Tennessee’s black walnut trees and has resulted in a quarantine that prevents Scott Countians and residents of several other East Tennessee counties from moving black walnut products and hardwood firewood outside the quarantine zone.
None of this is an indictment against free and global trade, which has benefited Americans tremendously over the decades. But it is an example of the negative impact that accompanies such trade, and clearly a cause of concern going forward.
The U.S. Department of Agriculture has traditionally been in charge of inspecting products before they’re allowed into the U.S. at ports and airports. That responsibility has now been moved under the umbrella of the Department of Homeland Security.
As Von Holle put it, “These screening agents have too much to do, and right now the focus is on finding bombs and weapons. That’s absolutely right, but we also need to be more aggressive about biological threats that could undermine large parts of the U.S. economy and harm our environment.”
■ Ben Garrett is editor of the Independent Herald. Contact him at firstname.lastname@example.org.