WHAT WE DO

Sixty years ago, America's eastern forests were a different kind of place - so different, in fact, that a 1940s visitor to Shenandoah National Park would barely recognize its forest today. From Maine south to Georgia, from North Carolina west to the Ohio Valley, forests were dominated by the magnificent, towering American chestnut, its population four times that of the birches, maples, and oaks we see today. Mountaintops in Great Smoky Mountains National Park appeared to be covered in snow when the chestnut trees bloomed with white flowers. Wildlife depended on the nutrient-rich nuts for food, and rural Appalachian economies thrived on the chestnuts that were shipped by the trainload to large cities like New York and Philadelphia each holiday season.

In the 1950s however, a chestnut blight likely imported from Asia began spreading aggressively, wiping out nearly every American chestnut tree in the country and dramatically altering eastern parks. Today, the blight prevents remaining chestnuts from reaching maturity. Hundreds of other invasive, non-native species have infested the national parks, threatening - and in some cases, permanently altering - these fragile ecosystems.

Non-Native Invaders

A 1998 study of threatened and endangered species in the United States found that non-natives are second only to habitat loss in threatening imperiled species.

These invasive, non-native species run the gamut. Feral pigs threaten native plants in Great Smoky Mountains, predatory lake trout threaten the native cutthroat trout at Yellowstone, zebra mussels clog waterways in the Great Lakes, and hundreds of introduced plant species threaten to overtake thousands of acres throughout the National Park System.

Beyond altered landscapes, non-native species can set off a disturbing domino effect across delicate ecosystems. At Shenandoah, for instance, a tiny sap-sucking insect introduced from Asia - the woolly adelgid - threatens to kill Eastern hemlocks that provide shade for mountain streams. The cool waters are necessary for the survival of native trout. Once the hemlocks are gone, the temperature of the streams will increase, making them uninhabitable for the trout.

In Theodore Roosevelt National Park in North Dakota, more than 60 non-native species have found their way into the park - including leafy spurge that invades native grasslands that wild bison and elk depend on for food. Joshua Tree National Park is being overrun by the rapid proliferation of non-native grasses such as cheatgrass and red brome, which spur larger and more destructive wildfires and compete with native plants and animals for precious water.

At Everglades National Park, non-native boa constrictors and Burmese pythons have invaded the waterways. Invasive melaleuca, Australian pine, and Brazilian pepper plants are overtaking native mangroves and cypress, while fishermen lament the decline of native largemouth bass, which are losing nesting habitat to exotic fish from Africa and South America.

In Big Bend National Park, the native cottonwood trees that traditionally lined the banks of the Rio Grande are quickly being replaced by non-native tamarisk. Eleven non-native fish now inhabit the river, competing with native fish for limited resources.

Millions Needed to Save Millions of Acres

In December 2004, Smithsonian magazine reported that "several thousand foreign plant and animal species have colonized the United States. All told, invasive species cost the nation upwards of $140 billion a year."

Since 1999, the National Park Service has effectively controlled exotic plant species on more than 167,000 acres - but 2.6 million acres remain infested. Certain parks, like Denali National Park, have aggressive programs to eradicate non-native invasions using biological methods (releasing natural predators that are not themselves invasive), physical (shoveling or hand-picking invasive plants such as dandelions every June), and chemical (applying fungicides and other chemical treatments)-but all of these approaches require solid management programs, sufficient staff, and adequate funding, which isn't always available.

The Park Service estimates that it would cost approximately $21 million to eradicate the woolly adelgid infestation in Great Smoky Mountains National Park. "There is no immediate source for this amount of funding," a 2004 agency memo said, "so land managers have developed a prioritized plan to determine which infested sites are treated and with which methods."

Key Recommendation: 
Increase Natural Resource Funding for Parks

A commitment to natural resource protection in the national parks is crucial in order to save the native landscapes that make the parks so distinctive.

Recognizing the need to strengthen funding for natural resource management in the parks, Congress established the Natural Resource Challenge in 1999. The program helps to fund initiatives to address the most critical threats, such as non-native and invasive species management, among other science-based projects.

But the Natural Resource Challenge, like many aspects of the Park Service's budget, is chronically underfunded. In fiscal year 2002, the program received $20 million; in fiscal year 2005, the program received $5 million.

Take Action

• Educate yourself >> Learn more about invasive species and how you can help. Be sure to clean your shoes before and after your visit to a national park, because seeds, spores, bugs, and viruses can easily be transported this way. If you drive or boat in a national park, be sure to scrub your tires, or your boat, trailer, and equipment, too. And don't release your pets into the wild.
• Make a Difference >> Plant a native garden in your own backyard. When gardening, be sure to avoid invasive plants such as Japanese honeysuckle, English ivy, bamboo, and purple loosestrife. 
• Volunteer >> to help clear invasive species from the national parks.
• Send a letter to your members of Congress encouraging them to support and co-sponsor the National Park Centennial Act.

Learn More

• For more information about invasive species, visit the website of the National Invasive Species Council.
  

NEXT >>