By Anne Paine, The Tennessean
Only a small portion of the state's hemlocks
- many that are hundreds of years old and stand 10 stories or higher -
are expected to survive a scourge of tiny insects that has advanced here
from the Northeast.
Chemical treatments are needed one tree at a time, and there's only so much money and time available.
Many of the long-lived evergreens already have died or are dying in Great Smoky Mountains National Park and elsewhere, leaving needleless gray hulks that no longer shade creeks and threaten to fall on whatever is nearby.
And the woolly adelgids - named for the clumps of whitish wax fibers they produce - are progressing more quickly than officials calculated across the Cumberland Mountains and Plateau toward some of the state's best-known scenery and hiking spots. The fast-reproducing Asian species has no native predator here.
risk are hemlocks that ring two of the falls at Fall Creek Falls State
Park and gorges of Savage Gulf that are lush with their canopies.
Hemlocks, which are known as the "redwood of the East," also line the
Fiery Gizzard Trail about 90 miles southeast of Nashville.
"When you walk along a creek, like at Fiery Gizzard, the only big towering tree is the hemlock," said Margaret Matens, with Friends of South Cumberland State Recreation Area, which includes the trail and Savage Gulf.
"If they should die, the effect to the environment is staggering."
often rugged landscape where hemlocks once stood tall has changed from
green to gray at Joyce Kilmer Memorial Forest in the Smokies, Shenandoah
National Park and throughout the insects' destructive path that ranges
from northern Georgia and Alabama to New England.
More than the scenery suffers. Streams and aquatic life do, too.
"Removal of these trees has all kinds of ripple effects that we're just beginning to understand," said Jon Evans, a biology professor at the University of the South, Sewanee.
are a "keystone species" that have little value as timber but are found
along springs and streams where their feathery canopy keeps the water
cooler in summer, and at a more even temperature year-round, than if
open to the sky.
That means healthier, more oxygenated water for
aquatic creatures, and it helps keep algae growth under control. Trout
and endangered Blackside dace are among the fish that depend on the cool
waters. Neotropical migrants including Swainson's warbler seek out the
hemlocks. Green salamanders and scores of other species are part of
The trees grow slowly, creating a multileveled
forest with branches serving as a ladder for animals to climb into the
tops of taller trees. Their needles release oxygen and their bodies hold
carbon sequestered over the years as they grow.
Having masses of
them die and rot releases that carbon back to the atmosphere and
overloads the waterways with woody debris, Evans said.
A group of largely state agencies formed the Tennessee Hemlock Conservation Partnership with the Tennessee Chapter of The Nature Conservancy
in 2011 to strategize about the 550,000 acres of public lands - 80
percent of it state-owned - in the Cumberland Mountains and Plateau.
Finding out where the hemlock stands are - and which are a priority to protect - has begun with mapping paid for by a Nature Conservancy grant and donations from Friends groups at Fall Creek Falls
and South Cumberland state parks. A state forestry division employee as
of last month is working full-time on the issue, but with state money
slim, much of the protection effort depends on donations.
on the data so far, about 24,000 acres in Tennessee could have
hemlocks, and treatment costs can run upwards of $80,000 per 500 acres
with currently available methods. That could amount to about $4 million
"We won't have enough funding to save them all," said
Trisha Johnson, a conservation coordinator with The Nature Conservancy,
adding that she hopes the group gets enough to save 10 percent of the
Chemicals aren't costly to treat trees - it's about $1 for
each foot the tree is in diameter. But it's time-consuming to reach the
trees and to administer the pesticide individually. This is done by
squirting the mix into the ground around the tree or, if near a stream,
injecting the tree itself. The largest hemlocks, whose trunks can be
five feet in diameter, take longer to circulate the substances and are
less likely to fight off the insects. At Savage Gulf, in advance of the
insects, more than 8,500 trees one foot in diameter or larger received
protective treatment in a project ended two weeks ago.
protect many of those trees for up to nine years. There are additional
23,100 mature hemlocks there, and 90,000 at Fall Creek Falls State Park,
according to the Landscape Analysis Lab at Sewanee that did the mapping to locate the trees in these areas.
The woolly adelgids, one of many invasive species that land managers
are trying to control, arrived in the United States in the mid-1900s and
were first seen in Tennessee in 2002. They could be carried from place
to place by birds, infested landscaping material, or people or animals
that they might cling to.
And then they proliferate.
"They are egg-laying machines," said Pat Parkman, director of the University of Tennessee's Lindsay Young Beneficial Insects Laboratory.
are females that reproduce twice a year - with no need of a male. In
one year, a single insect, with subsequent generations, can result in
90,000 additional adelgids.
They are small, less than one-sixteenth of an inch, and secrete their wooly mass to protect themselves and their eggs.
another line of defense, are being grown at the UT lab and set loose at
locations around the region. This includes a species native to the West
Coast and another from Japan, where the woolly adelgid originally came
About 800,000 beetles from the lab have been released, some on state lands, including Tennessee Wildlife Resource Agency's
North Cumberland and Catoosa wildlife management areas and Roane
Mountain and Cumberland Mountain state parks. But there are many more
woolly adelgids in these locations than beetles. The beetles have to
thrive and build up, which could take several years.
"We're trying to get out ahead of this," Parkman said. "It's sort of an arms race."
a test, a helicopter dropped an adelgid-killing fungus blended with
whey on a few heavily infested acres of TWRA land. It reduced adelgids
significantly, but the U.S. Environmental Protection Agency hasn't yet
approved the concoction for large areas.
Tennessee has the
advantage of learning from other states and also the National Park
Service that experienced the insects sooner. In the Great Smoky
Mountains, a dramatic change in the forest has already taken place with
"a lot of the old growth trees hammered early on," said Jesse Webster,
with the park.
Aggressive treatments begun in 2002 are avoidin g
"ecological extinction" of the park's hemlocks, so at least pockets will
remain and new hemlocks will follow, he said. The park has chemically
treated trees in campgrounds, on roadsides and at back-country campsites
and finds it cheaper than having to later remove large dead trees,
which otherwise are a serious hazard.
Private lands are another matter.
Wendy Fish of Nashville learned through Save Georgia's Hemlocks how to apply the pesticides and has taught others in her hemlock-strewn vacation community near Savage Gulf.
"We call them 'Woolly Day,' " she said of neighborhood work sessions.
She and the neighbors treated 1,000 trees last month and have many more to go.
very motivated," she said, adding that the community had expected to
have a couple of more years before the insects arrived.
insects, which had been spreading on average 10-20 miles a year, seemed
to leapfrog and showed up this year farther to the southwest on a tree