The Why Files The Why Files --

Parks or Playgrounds?
POSTED 30 DEC 2004

Out, invaders, out!
Stopped  cars block both lanes of highway in national park.One thing park inventories can reveal is unwanted guests. When people transport non-native plants or animals outside their native geographic range, they can spread quickly in the absence of animals and diseases that normally keep them in check, dramatically changing a landscape.

Traffic in the national parks is emblematic of Americans' attraction to them. But, scientists say, pollution from cars is a top contributor to ailing parks. NPS photo

Invasive plants (read: weeds) reportedly crowd about 2.6 million acres in the national park system, in some cases radically reducing natural biodiversity. Offenders, plants and animals alike, include the likes of:

Asian swamp eels are gobbling up native fish by the thousands in the Everglades, where native plants are being smothered by the invasive climbing fern.asian swamp eel, USGS: brown eel on grey background

Native trees and, in some cases, entire forests in the Great Smoky Mountains and Glacier National Parks are falling victim to introduced insects and diseases.

Invasive lake trout have killed off most native trout species in many of Yellowstone's lakes and streams. Grizzly bears, which rely on native trout as a seasonal food choice, can't eat the nonnative trout because they swim deeper in the water.

The adelgid, a little insect transported from Europe to Canada on Christmas trees, has spread down the Appalachian Mountains and into Great Smoky National Park, where it attacks Frasier firs.

The Natural Resource Challenge created funds for Exotic Plant Management Teams -- modeled after the approach used to fight wildfires -- to combat invasive plants. Four regional teams began working in 2000 and have been joined by a dozen more since. The Park Service reports that, to date, the teams have eradicated six invasive plant species from the parks.

The teams have made a sizable dent in removing certain plants from wild lands, says Bill Wade. But the best progress has come with a growing understanding of the methods that work best.

Visitors cross babbling rapids on wooden bridge.Conservationists repeat a "take only pictures, leave only footprints" mantra. These hikers, enjoying the Yellowstone River, appear to be listening. NPS Photo

Working outside of park boundaries -- and thus with local officials -- is key in preventing re-infestations. Establishing buffer zones on private land surrounding parkland can help. Recognizing areas that are easily colonized by invasive species because of climate or geography can help set funding priorities. Hawaii, for example, is one of the most isolated island groups in the world, with about 10,000 endemic species. Since they are found nowhere else on Earth besides Hawaii, they are especially vulnerable to extinction. Hawaii is also a major trade hub, and the U.S. region most damaged by invasions -- by vertebrates, invertebrates, and flowering plants.

According to a recent report, Hawaii "is in the midst of an invasive species crisis affecting not only the archipelago's highly endemic biota, but also overall environmental and human health" as a result. In the Invasive Species Specialist Group of the World Conservation Union's list, "100 of the World's Worst Invasive Species," Hawaii was home to 47.

There is a national quarantine system, but it was designed to protect agricultural land from weeds and pests, with little reference to the protection of natural areas from biological invasions. (See "The challenge of effectively addressing the threat of invasive species" in the bibliography.)

The air outside is frightful.
Next to invasive species in the lineup of scientific priorities is, we hear, pollution. Air and water know no borders, and so the parks are "at the mercy of the surrounding environment," says Dodd.

Nearly all of the pollution that harms parks comes from power plants, cars, and industries located outside of park boundaries, says Joy Oakes, Mid-Atlantic Regional Director of the National Parks Conservation Association.

"This same pollution travels first across backyards and farmyards and the schoolyards, where it has impacts on human health and agriculture," Oakes points out. Tackling pollution in the parks, she says, should therefore be a joint effort between the park service and local, regional, and national government.

Graphic shows poor air quality in national parks.
Think you're getting fresh air in the national parks? Think again. Courtesy National Parks Conservation Association

Because few parks have a history of monitoring air quality, Oakes says, it can be difficult to know whether pollution is getting better or worse. For the parks that do monitor air quality, Oakes and her colleagues looked at trends beginning in 1991, when the Clean Air Act was last strengthened, until 2003. "We were taken aback to find that in seven, ozone has actually risen since 1991, although it has declined slightly across the country as a whole," says Oakes.

Earlier this year, the National Parks Conservation Association ranked the most polluted parks:

Acadia National Park, Maine: Acadia's 45,000 acres of craggy Atlantic shoreline and mixed forest is afflicted with ozone pollution, acid rain, and mercury deposition.

Everglades National Park, Florida: As the only subtropical preserve in the country, the Everglades are host to dozens of endangered and threatened species. Southern Florida registers the highest mercury deposition levels anywhere in the U.S.

Glacier National Park, Montana: The park's temperature has risen dramatically in the last century, and its glaciers are retreating. Scientist suspect global warming is the culprit.

Great Smoky Mountains Park, North Carolina and Tennessee: The "salamander capital of the world" is the country's most-visited park. Also one of the haziest, the Smokies often register ozone levels high enough to damage human and plant health.

Mammoth Cave National Park, Kentucky: Seven endangered species are threatened by mercury pollution in Mammoth Cave, which harbors the most extensive known cave system in the world.

Shenandoah National Park, Virginia: Shenandoah is home to about 1,400 plant species, threatened by acid rain and ozone.

In the east, parks like the Smokies, Mammoth Cave, and Shenandoah are downwind of old, coal-fired power plants, says Oakes. Because of outdated controls, these plants can spew six to 12 times more sulfur dioxide (the pollutant responsible for most of the poor visibility in eastern parks) than new plants.

Four skiers slice through snow and trees on mountain.
It looks serene on a clear day, but Shenandoah National Park ranks as one of the most polluted. NPS photo

California's fast-growing San Joaquin Valley is surrounded by mountain ranges. Pollution from cars, refineries, and power plants is trapped within the valley before blowing south to Sequoia-Kings Canyon National Park, making it the smoggiest national park. In the past five years, the park has recorded almost as many unhealthy air days as Los Angeles.

The role of science, Oakes says, is to find and report changes in the parks that sprout from pollution. The role for the rest of us, well, is another story.

-- Sarah Goforth

Want more? See our pollution-free bibliography.


Megan Anderson, project assistant; Terry Devitt, editor; Sarah Goforth, feature writer for this story; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

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