As stand after stand of towering hemlocks falls to the appetite of an insect smaller than a grain of rice, foresters and wildlife managers alike are scrambling for an answer to the hemlock wooly adelgid.
The invasive pest is still chomping steadily through Appalachian forests, threatening to forever alter the ecological landscape of the mountains.
As if the death of hemlock trees across the Southern Appalachians wasn’t bad enough already, forest researchers believe the loss of hemlocks will alter the carbon cycle of forests.
An exotic insect known as the hemlock wooly adelgid has a death grip on hemlocks throughout the mountains. The giant hemlocks are an anchor tree species in the ecosystem and their loss could have severe ripple effects, from species that depend on them to the cool, moist microclimates found under their dense evergreen branches.
Forest service researchers at the Coweeta Hydrological Laboratory in Macon County now believe the die-off of hemlocks will also have a detrimental effect on hydrology and carbon cycle.
“The study marks the first time that scientists have tracked the short-term effects hemlock woolly adelgid infestations are having on the forest carbon cycle,” said Chelcy Ford, an ecologist with the Southern Research Station who was involved in the research.
Researchers tracked changes in the carbon cycle of infected hemlock stands over a 3-year period. Scientists measured components of the forest carbon cycle — including tree growth, leaf litter and fine root biomass, and soil respiration — finding a decline of 20 percent or more for some of the variables in just three years.
Another piece of news emerging from the research is that hemlocks are dying far more rapidly than initially feared. A total loss of the tree is expected with the next decade.
Researchers noted that other tree species are quick to occupy the space given up by their dying hemlock neighbors.
“We’ll continue to monitor this, but it’s still too early to predict just how different these forests will look 50 or 100 years from now,” Ford said.
Jesse Webster consulted his GPS and eyed the tangle of rhododendrons stretching out of sight up the mountainside.
Somewhere beyond the gnarled thicket lay a massive grove of old-growth hemlocks — at least that’s what aerial photos suggested. It was Webster’s job to track down the trees and if it wasn’t too late, inoculate them against a deadly pest.
As Webster and his ground crew left the trail and bushwhacked their way forward, Webster wouldn’t know until he got there whether he was too late to save the trees from the reviled hemlock woolly adelgid.
The unchecked marauder, hardly the size of a pinhead, is swiftly undermining the region’s ecosystem. It kills giant hemlocks in as little as five years from first latching onto the tree’s branches.
Webster, a park ranger in the Great Smoky Mountains National Park, is the leader of a tactical team trying to save one grove at a time. He’s horribly crushed when he arrives at a stand only to find it’s too late. The needles have been stripped from the tree, leaving only a grey skeleton of branches. But this time, like every time, he holds out hope.
“Hope springs eternal,” Webster said as he crawled up the mountainside.
While the park doesn’t have a lot of old growth forest, what it does have is mostly hemlock.
“Back in the days when a lot of the park was logged over the hemlock wasn’t a sought after valuable lumber tree,” Webster said.
The average age of hemlock groves Webster saves date to 1750, with some pushing back 400 and even 500 years.
“Their age alone to me is justification for the work that we do,” Webster said.
But there’s more to it than that. The hemlock is what Webster calls a “keystone” species. Owls and bats nest in them. Bears den in them. Flying squirrels use them as a launch pad. They’re the guardian of their own microclimate — their dense branches the very reason cool moist coves are cool and moist. Even the prized Southern Appalachian brook trout could falter when the shade hemlocks provide along creeks disappears, giving rising to warming water temperatures known to kill off brook trout.
“We are trying to preserve the hemlock forest,” Webster said. “The loss of that is more dramatic than just the collateral damage we see in one small area around a hemlock tree.”
Webster knows of 47 species that live in or on hemlocks — some specific to hemlocks only. There’s a fungus that grows only on hemlocks, and beetles that eat only that fungus. But Webster and his crew can’t help form a bond with the tree in front of them.
“One thing that keeps me going, you literally are saving that tree,” Webster said. “People say save the rain forest, save the whales. But with this you are actually, literally saving that tree.”
So it’s hard when Webster can’t save every one of them, but instead has to walk by those that don’t make the size cut-off.
“It’s the toughest part of the job, deciding what to cut off,” Webster said. “You can’t do all of them, so how do you decide, ‘Well those trees, we aren’t going to be able to work with those.’”
His rule of thumb is a diameter of eight inches and up.
“Sometimes you get suckered in and you want to do a four-inch tree,” Webster said. Which he does, justifying its potential as a future seed bearer.
On a bad day, one with lots of bushwhacking, the crew might treat only 40 trees. On a good day, it’s 150.
The woods Webster tromped through on one expedition last winter was like a scene from The Lord of the Rings, one of those medieval forests with moss-covered boulders ensnared by twisted, weathered roots. The hemlocks’ girth was so wide four adults holding hands couldn’t reach around the trees.
“You are looking at 200-, 300-year-old trees right here,” Webster said.
As he sidled up to the first hemlock, he cast a glance skyward, first following the trunk then the tracing the branches of the massive canopy until he could no longer keep track of where this hemlock stopped and the next one started.
He was dwarfed by the giant trees, hardly more significant than a mouse scuttling over their roots far below. It was hard to imagine this cathedral crashing down, reduced to a graveyard of slain giants. Yet that’s why Webster was here: to save them.
“These trees are dying,” he said.
He quickly got to work. Kneeling now, he unscrewed the Nalgene water bottle and dropped in a pouch of powder the size of a pack of gum. He shook the bottle until it dissolved.
Meanwhile, his partner Kristine Glover had unfurled a tape measure and was eyeing the girth of the tree.
“Three feet,” she said. That told Webster how many ounces of the solution to use.
As Webster doused the soil around the tree roots, he had no qualms about the impact the chemical could have on nature. It’s the same active ingredient found in flea and tick medicine used on pets. It is harmless to animals, acting on invertebrates only. That could pose a problem for aquatic life, though, so it isn’t used near streams.
The chemical was engineered to bind with organic compounds, so it migrates no more than 3 inches a year through soil. With a half-life of five months, it would be nearly neutralized before it could move that far.
Before the crew moved to the next tree, Glover pulled a can of white spray paint from her hip holster. She blazed the tree with two quick squirts. Someone in her boots years from now would see that blaze and know it had been treated.
Slowly but surely, the crew was working its way through the forests of Cataloochee Valley, a section of the park rife with old-growth hemlock.
“Cataloochee is the land of the hemlocks for sure,” said Troy Evans, part of the ground crew. “There are just so many hemlock stands you can’t get to them all in time.”
But those they do save will one day be the seed bearers that help to reforest the landscape with a new generation of hemlocks.
“I believe by the end of my lifetime, I will see natural regenerating hemlocks in some of these coves where we are working,” said Webster. He’s 38 now.
Some see the effort to save hemlocks as a long shot, but those on the ground don’t want to look back years from now and wonder “what if” they’d only tried harder.
“Our goal from the very beginning has been to preserve remnant old-growth forest throughout the park,” said Park Ranger Tom Remaley, the Smokies chief forester.
There’s a lot of reasons: the trees themselves, the species that live in them and under them, people who want to visit a national park and see what a hemlock forest looks like.
But Remaley also talks about the long view of “genetic preservation.”
“If we want to at some point in the future repopulate the park with hemlocks, we need seeds from hemlocks that are native to the Smokies,” Remaley said.
When Remaley came to the park in 2004, the task was daunting. The adelgids had slipped deep into the park already, and ferreting them out wouldn’t be easy.
Thanks to the foresight of the park’s foresters, the first daunting task was already behind him: knowing where the hemlock groves were in the vast and thickly forested park. In the early 1990s, as the adelgids’ steady march down from the north closed in on the Southern Appalachians, the park’s foresters set about mapping every hemlock stand in the half million acres of the park.
They analyzed aerial photos — hundreds of them — spanning every corner of the park. To their luck, the photos were taken in winter exposing the evergreen tops of the hemlocks. But the photo mapping alone wasn’t foolproof.
“Yes, they looked like hemlocks from the photos, but are they really?” Remaley asked. “So we went out and ground truthed them.”
Curious just how old these giants were, the foresters bored into the occasional trunk with a hollow metal tube, penetrating deeper and deeper through the eons of time until they reached the center. Extracting a thin sliver of wood, they could then tick off tree rings like a cross-section of time.
“Hemlocks are some of the oldest trees in the park. It’s common to find trees over 300 years old,” Remaley said. “Some of the trees we couldn’t get to the center of because they were too big.”
The oldest weighed in over 500 years old. A tiny seedling when Christopher Columbus landed on the Americas, those oldest hemlocks were witness to centuries of human occupation in the mountains, from Cherokee hunting parties to the birth of modern towns. They escaped the clearing by early settlers and later the loggers’ axe — presumably saved for good with the park’s creation — only to be brought down by an insect no bigger than a pinhead.
The intensive mapping and dating revealed 1,400 acres of old-growth hemlock forest scattered throughout the park.
“It gave us an idea not only that we have more old growth hemlock than anywhere else, but that hemlocks really reach their peak here in the Southern Appalachians. We were finding the tallest and largest hemlocks anywhere,” Remaley said.
To make the cut as old-growth, the hemlocks had to be at least 150 years old. The plots of hemlock hold-outs ranged from a few acres to a couple of hundred.
Most of that hemlock forest resides on the North Carolina side of the park, with Cataloochee emerging as the bastion of old-growth hemlock.
Once the mapping was complete, the foresters watched and waited. Everyone was on the look out for the telltale sign: the fuzzy white adelgid egg sacks covering the underside of branches like snow. It was first spotted in the area around Fontana Dam, the far southwest corner of the park, in 2002. Within a few months, signs popped up in other far-flung districts of the park as well.
Foresters initially tackled the outbreaks the only way they knew how, with an organic solution sprayed on by hand. In hindsight, it was like spitting in the wind. It washes off with the first rain and only kills adelgids it comes in direct contact with — posing a serious the challenge to douse every branch in a 100-foot tree armed with nothing but a backpack sprayer.
But they held out hope that the isolated sightings were a fluke and could be stopped.
“We thought maybe an isolated bird came and landed there and had it on its feet,” Remaley said. “We quickly found that wasn’t the case. It was in a lot of other places.”
The fallacy of spraying giant trees by hand led the park to switch strategies: chemical inoculation sucked up by the tree’s roots. No one knows how long the inoculation lasts. Foresters initially estimated three or four years. But it appears it’s longer than that — possibly even seven years. The longer staying power is allowing the park to cover more ground. Instead of spending their time revisiting hemlock stands for a second dose, foresters can keep hitting new territory.
“I am getting more and more encouraged that once we have the systemic pesticide in the tree that is going to buy us a lot of time,” Remaley said. Not only are the treatments lasting longer, but the price has gone down — dramatically. When the park first started, a packet of chemical cost $24. Now it is around $7. Before, Bayer held a patent on the chemical, but it expired in 2006. An influx of cheaper generics hit the market.
“There is no way we could have treated the number of trees we have treated otherwise,” Remaley said.
Labor is now the most costly part of the project, not chemicals. The hemlock program in the park had a budget of $800,000 last year. Of that, $250,000 was for chemicals.
Of course, foresters can’t keep treating the hemlocks forever. They hope to stave off the adelgid with the treatments long enough for a predator beetle that eats the adelgids to establish itself in the park. Since the adelgid comes from Asia, there’s nothing native to the Smokies that preys on it. So the park service is introducing the predator beetle itself. Two different predator beetles are being bred in laboratories and released into the park where they will hopefully take up residence of their own. A third is in the trial stage. No one knows when the predator beetles will ramp up enough to put a dent in the adelgids.
“It could be 10 to 15 years from now. It could be 20 years from now,” Remaley said.
Until then, the crews have to keep them at bay with the treatments. So far, crews have saved 104,000 hemlocks.
“If we just walked away and never did a thing 99.9 percent of them would be dead,” Webster said. “Now if we just walked away and totally dropped the ball, tens of thousands of trees would still be here 5, 10, 15 years from now.”
A lot rides on the predator beetles. It is more than a grand experiment: the future of a forest, of an entire ecosystem, hinges on their success. The park has released 398,088 predator beetles into the park so far.
Beetle releases occur weekly in the park during late winter and spring. Transported from a beetle-breeding lab on the campus of the University of Tennessee at Knoxville, thousands of beetles are being distributed into every corner of the park.
While some are simply sprinkled on the branches of infected smaller hemlocks by hand, getting the beetles high up into the canopy of old-growth hemlocks is more of a challenge. The rangers rig a slingshot out of biodegradable rope, aim for the upper branches, then hoist a coconut hull basket teeming with predator beetles into the tree. The rope and hull are left to decompose.
While it’s far too early to tell, the predator strategy appears to be working.
“We know they survive. We know they eat adelgids and we know they are reproducing,” Remaley said. “What we don’t know is how fast they are reproducing in the wild and at what point they will exert a control on the adelgid population — enough control so the trees can still survive.”
Remaley said the park will never be completely rid of adelgids. The goal is simply to keep the adelgids in check.
“The trees can survive with a lower level of adelgids on them,” Remaley said. Just not the great army there is now.
In the northeast, the adelgids are kept in check by harsh winters. That’s not the case in the Southern Appalachians, however, where they breed incessantly up to two times a year.
While known simply as “the predator beetle,” there’s actually more than one species. The park is hedging its bets with a “complex of predator beetles,” Remaley said.
Different beetles attack the adelgid in different ways, or are active at different times of year.
“We hope over time, if we find the right ones, they will control the adelgid and that more intensive effort of using the chemical and ground crews will become less necessary,” George Ivey, a consultant and grant writer for Friends of the Smokies, said.
The beetle-breeding laboratory in Knoxville now cranks out 130,000 to 150,000 beetles a year.
There’s another natural balance coming into play. The onslaught of adelgids that marked the early years has peaked and numbers are now crashing.
“They can’t maintain their numbers because there aren’t as many hemlocks,” Webster said.
Money to combat adelgids was slow to materialize from the park service at first. At times it was hard to tell which fight was more daunting: the one for funding or the one against the adelgids.
Had it not been for Friends of the Smokies, the adelgid’s hold by now would likely be irreversible. When the adelgid first appeared, the park had no money in its budget to tackle the problem.
“Immediately Friends of the Smokies provided seed money of $10,000 or $15,000 to experiment with some treatments,” said Ivey.
Since then, Friends of the Smokies has provided more than $1 million in funding for the hemlock initiative.
“The initial thrust of our work was to try to fill the gap until federal funding could catch up,” Ivey said. “To wait an extra two years to get that lab finished just didn’t seem acceptable. That was the real push, and part of the appeal to donors was not to foot the bill for everything but to be the catalyst to ramp things up as quickly as possible.”
It worked. The federal government is largely footing the bill now, but the Friends of the Smokies had to bridge the gap until the wheels of bureaucracy turned.
“Some government agencies and scientists took a fatalistic approach ‘Well you are going to lose them and that’s just how it is,’” Ivey said. “That’s the way it has been in other parts of the county where an effort wasn’t mobilized. It was thought the problem was too big or the money too small and that’s an attitude we have wrestled with to a certain extent here, too.”
The Smokies continues to fund a special tactical team assigned to the North Carolina side of the park.
Friends of the Smokies garnered support from two crucial allies. One was the Fred and Alice Stanback Foundation, an amazing pair of environmental philanthropists from Salisbury, N.C. The other was the ASLAN Foundation in Tennessee.
The Smokies has become a model for how to combat the adelgid. While the playbook is evolving daily, right now, it’s the only one out there.
“No other park has spent the effort and time that we have on this,” Webster said. “This really is a battleground.”
There are still some who argue the effort is a waste of money — a crapshoot at best, fatally flawed at worst. But for those who cherish the tell-tale signs of an old-growth hemlock forest, the gnarled moss-covered roots twisting over the ground and deeply-rutted bark on trunks stretching nearly out of sight, you can’t put a price tag on the hemlocks’ last stand in the Smokies.
“We will probably be the only place where you can go see an old-growth hemlock forest,” Remaley said. “If you want to see an old growth hemlock forest, this is where you are going to come.”
It is easy to be overwhelmed by the enormity of the crisis, but Frank Varvoutis, a former park ranger who was on the first tactical team treating hemlocks in the park in 2004, believes it is a worthy cause.
“If they could have done something for the chestnuts back then, don’t you think they would have?” Varvoutis asked.
Varvoutis became so enamored with hemlocks, he started his own company called Hemlock Healers committed to helping private landowners save hemlocks in their yards. But his days toiling in the park’s old-growth stands will always be part of his soul.
“They are beautiful trees. Some of them are 400 and 500 years old,” Varvoutis said. “To think you are standing next to something that old, that was around when Columbus came to this country, it blows your mind.
A new breed of predator beetles that could help fight the hemlock wooly adelgid were released in the Great Smoky Mountains National Park two weeks ago.
The hemlock wooly adelgid is a bug from Asia that has invaded the Southern Appalachian Mountains and is rapidly infesting hemlock trees. Without action, the region could lose nearly all of its hemlock trees within five to 10 years, leaving a gaping hole in the forest ecosystem and the landscape.
The eastern hemlock has long been one of my favorite trees. Like many people reading this column, my wife, Elizabeth, and I have a number of very large specimens growing on our property, especially alongside a creek that traverses the cove we live in. And, of course, we’re very concerned about losing these wonderful trees to the hemlock woolly adelgid infestation that is currently ravaging the southern mountains. All of our hemlocks show signs of the infestation, and we will hate to lose them. This column, then, is sort of an ode to the hemlock.