By Todd Wilkinson
At Clingmans Dome, the highest overlook accessible by car in Great Smoky Mountains National Park, Keith Langdon, supervisory biologist, is listening intently as a group of visitors ponders a question: What killed all the trees?
For miles, the park's famous endemic Fraser fir forest—which accounts for 75 percent of all Fraser fir in the world—is dead or dying. The decaying trunks, stripped of their needles and bark, are testaments to the lethal force of a tiny insect—the balsam wooly adelgid—whose lethality rate on mature Frasers hovers near 100 percent.
Native dogwoods are being killed off by a lethal fungus. |
But as nightmarish as the outlook is from Clingmans Dome, experts say it is only part of a larger drama playing out in forests across America. From the adelgid infestation in Great Smoky Mountains, to lethal fungus killing off native dogwoods along the Eastern seaboard, to a deadly organism causing Sudden Oak Death Syndrome along the California coast and a fatal blister rust on whitebark and limber pines from the Pacific Ocean hundreds of miles inland to the Rockies, America's forests are under assault. |
"This biological trainwreck has been tracked for a long time by the scientific community, but we've been unable to respond for a variety of reasons," says Dr. David Graber, the senior science advisor in Sequoia-Kings Canyon National Parks and a nationally respected conservation biologist. One reason, he says, is that these foreign diseases are incredibly virulent and made more potent by pollution and possibly by the onset of climate change. Another is that identifying disease-resistant trees and growing them successfully can take years.
Some of the biggest losers in years to come, aesthetically, ecologically, and even financially, will be national park ecosystems that historically have functioned as biological warehouses of America's great diversity.
"The imminent loss of our native forests demonstrates, as poignantly as anything we've seen, that it's not enough to draw a line around a park and call it protected," says Joy Oakes, NPCA's Mid-Atlantic regional director.
The devastation in Great Smoky Mountains is a case in point. The chilling, ghostly scene created by the Fraser fir decay is only part of the challenge to the park's lush Appalachian mosaic. In the park's American beech forest, trees are being ravaged by a one-two punch of boring insects and a fungus introduced to North America from Europe, probably through the contaminated soil of imported potted plants.
Once the insects feed on a beech's protective layer of bark, the fungus moves in and kills the tree's main trunk stem. At lower elevations, surveys show that the first wave of the hemlock wooly adelgid, introduced from Asia and a close cousin of the balsam adelgid that feeds on the Fraser fir, is assailing the park's hemlocks.
The insect already has assailed forests in New England and other national park units, including Delaware Water Gap National Recreation Area in Pennsylvania and Catoctin Mountain Park in Maryland. Now it is menacing a forest that contains trees that offered shade to aboriginal American Indians and to frontier settlers such as Daniel Boone.
"We have been anticipating the hemlock wooly adelgid's arrival and now are releasing federally approved ladybug beetles imported from Japan to fight the outbreak. But we realize it's a last-ditch attempt to hold the line," Langdon says.
Tree plagues reaching into every corner of the park are made worse, scientists say, by chronically bad air. Ozone produced upwind by power plants, auto emissions, and factories routinely settles on trees, stressing them and leaving them more susceptible to disease and insects. Within the span of a human generation, eight or nine native tree species, including butternut, dogwood, and elm, are likely to disappear or suffer severe declines in a park beloved for its foliage. |
 Dirty Air Stresses Trees, People
NPCA is attacking the forest devastation problem on several fronts. In addition to testifying before Congress about the need for larger research budgets in land management agencies, the association is opposing Bush administration proposals to relax clean air regulations aimed at some of the country's biggest polluters. During the summer of 2002, NPCA joined with other conservation organizations, which together represent millions of members, in writing a letter to President Bush, telling him that his proposal to relax clean air enforcement was pure folly.
"Both Congress and this administration have the opportunity and obligation to do what's needed to protect both parks and people from air pollution," says Joy Oakes, NPCA's Mid-Atlantic regional director. "The problems besetting our trees, which are the natural factories of clean air, should be interpreted as a warning sign. Not only are trees stressed by dirty air, and not only is it impairing the visibility of many landmark views in parks, but studies show that air pollution annually contributes to 30,000 premature human deaths."
The fact that wildland parks, from Grand Canyon to Sequoia-Kings Canyon to Great Smoky Mountains and Acadia, are supposed to be refuges for clean air but have suffered from largely urban air pollution exposes the magnitude of the problem.
Not long ago, Don Barger, NPCA's Southeast regional director, testified before Congress on a "code red" air day, when pollution levels are unhealthy. Barger left members of Congress speechless when he pointed out that as sullied and unhealthful as the air was that day in Washington, D.C., hikers in the forests of Great Smoky Mountains or Shenandoah were encountering ozone levels even more hazardous.
"The threats to our forests and the scientific regulation of air pollution can, on the surface, seem very complicated, but in reality the solution is simple," Oakes says. "We must do more, not less, to reduce the contaminants that cloud our skies, and industry must be required to be as clean as possible, not as dirty as it can get away with. This administration wants us to believe that pollution will go away if citizens politely ask industry to voluntarily be responsible, but we know that doesn't work."
—TW | |
It's the same across the National Park System, where dozens of major tree species are threatened and hundreds, if not thousands, of secondary species could be affected as well. Some of the devastation will be as complete as the blight that wiped out America's chestnut trees more than 50 years ago and as landscape-changing as Dutch elm disease.
Even today, some people remember the havoc caused by the chestnut blight. Hailed as the "redwood of the East" for their ability to grow to 100 feet and reach ten-foot diameters, chestnuts constituted an astounding 50 percent of mountain forests in the United States. They were used in home construction, produced commercial nut crops, and like oaks, provided food for wildlife. Then they were beset by what some regard as one of the worst natural calamities in the nation's history, the appearance of a fungus brought to the United States from Asia on exotic trees.
Within a few years, nearly all of the wild chestnuts—which placed together would have covered 9 million acres—were gone. Dutch elm disease, another import, destroyed thousands of one of the most popular shade trees of cities and towns in the East and elsewhere.
 Losing a tree species can have cascading effects, many of which are not fully understood. Certain trees, for example, may be hosts for bees that serve a vital role as pollinators. If pollination does not occur, then fruit-bearing trees and plants do not produce foods for a variety of other species. Hemlocks, which typically grow along streams, provide shade that cools water temperatures and allows trout and other fish to survive summer heat and lower water levels.
In the case of Pacific dogwoods in the Northwest and flowering dogwoods in the Southeast, the tree functions as a depot of vitamins for many organisms. Of all the deciduous trees, flowering dogwood holds the highest percentage of calcium in its trunk. Dogwood berries, which are high in protein, provide an energy boost for migratory birds.
Perhaps nothing provides a better illustration of the importance of one tree species than the devastation being caused by blister rust.
Decades ago, this pathogen arrived in the Pacific Northwest and immediately spread, decimating whitebark and limber pines in a swath stretching from the ocean hundreds of miles inland to the Rockies. Blister rust also is attacking sugar pine in the Sierra Nevada, and botanists are asking themselves whether any sugar pines—the largest pine on the continent—will be left in 35 years.
Blister rust has also exacted a huge toll on whitebark pine in Glacier National Park in Montana and has reached the doorstep of the greater Yellowstone ecosystem. The loss of whitebark pine and its impact on the Lower 48's largest and most imperiled population of grizzly bears could be immense, says Kate Kendall, a senior biologist with the U.S. Geological Survey and a global expert on bears and whitebark pine.
Whitebark pine produces cones laden with highly nutritious seeds that grizzlies gorge themselves on before hibernation. The seeds' fat content enables the bears to put on enough weight to survive the long winter slumber, have successful pregnancies, have larger litters of cubs, and ultimately remain nutritionally sustained so that they don't wander into human settlements in search of food.
"With regard to grizzlies, the impact of blister rust is that you're removing a preferred and highly valued food," Kendall says. "It's just another significant food source being taken away in the wake of losing important salmon and trout spawning streams. Yes, bears can survive because they are highly adaptable and opportunistic, but it's pretty clear that not as many bears will be supported by a given area of land as they were in the past."
Bears are not the only park fauna affected. Whitebark pine, which has been documented at ages approaching 1,300 years, provides food and nesting cover for many different birds and rodents and serves as "snow fences" that trap snow that ultimately feeds vernal springs relied on by ranchers in the West for irrigation. |
In Yellowstone, this tree bears the marks of a grizzly. |
In Glacier, 42 percent of all whitebark are dead and most of the rest, Kendall says, "are all but dead." Of the survivors, 80 percent are infected with rust.
Some conservationists, who attempted unsuccessfully to have the U.S. Fish and Wildlife Service declare whitebark pine an endangered species, are preparing to resurrect the campaign.
In addition, the U.S. Forest Service is a few years into an innovative program of nurturing natural, disease-resistant whitebark and limber pine and experimenting genetically with trees that might reach maturity earlier. As things stand now, it takes seedlings planted today 80 years before they produce their first crop of seed-bearing cones. Helping whitebark pine survive may require extreme measures, including clearcutting patches of other trees to help healthy whitebark grow, replanting slopes with whitebark seedings, and lighting lots of small wildfires.
"We are going to witness profound changes with native forests in our lifetime, and it behooves us now to think in a multi-century context particularly in parks that are facing ongoing threats in perpetuity," Graber says. "This is going to require a change in attitude and that it be empowered by the will of society, because some of the planning decisions we will have to make may never produce results in our lifetime. We probably will have to contemplate landscape manipulation in ways we never thought we would. But long before we commit ourselves to doing these things, we need to do extremely sophisticated and complex modeling of ecosystems so we can make wise decisions. I'm not an optimist, but I know that as bad as things are, they could be worse."
Currently in Great Smoky Mountains National Park, park ecologists are hastily conducting surveys that involve beating gently on limbs of surviving trees and collecting all the insects that fall into a waiting net below.
"We're doing this to identify not only what we have, but what we could lose," Langdon adds, noting that when the American chestnut was wiped out by blight, no one was there to document the array of life that depended on those trees for survival.
"The fact is that we are not going to be left without 'a forest,'" Langdon says. "There will still be green trees growing out there, but in terms of the diversity known and enjoyed by our grandparents and parents, that forest will be gone and replaced by something much simpler."
Saving the Urban Jungle
Concern about trees' future is resounding through the Park Service's "urban forest" too. The great hand-planted trees that line the National Mall in Washington, D.C.—a key attribute of the stately, inviting feel of the capital city—are not immune. American elms, all 600 of them on the Mall and 3,000 in the federal Washington greenbelt, are regarded as "organic monuments" that form the arboreal latticework, the "green superstructure" of the Mall, says Jim Sherald, plant pathologist and chief of natural resources and science at the Park Service's Center for Urban Ecology.
According to Sherald, people forget how valuable trees are, aesthetically and economically, until they are gone. "Does the public take the urban forest for granted? The answer is 'yes', and that's a problem," he says, noting that in suburban areas, the presence of healthy mature trees adds between 5 and 10 percent more value to a lot. But more important, trees are part of the fabric of life and serve as backdrops to the American experience.
When Dutch elm disease surfaced in Washington, D.C., in 1947, agency arborists were quick to respond because they knew what was at stake. They destroyed diseased trees and worked side by side with the National Arboretum in experimenting with disease-resistant varieties. It worked. However, in recent years, the maintenance budget for the District's forest, which, all told, includes 17,000 trees (including 3,000 exotic cherry trees), has not kept pace with costs, and the Park Service has had to farm out its caretaking duties. Some worry that disease control could fall through the cracks.
"The point we try to convey is we're a minor voice within the Park Service," says Sherald. "There is a general appreciation for the wildlands we manage, but an underappreciation for the horticultural lands we manage and the demands it requires."
—TW |
Todd Wilkinson lives in Bozeman, Montana, and is a regular contributor to National Parks.
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