Invasive Plants

The spread of invasive species is a major factor contributing to undesirable landscape level change and ecosystem instability in national parks. The National Park Service (NPS) is working to manage invasive species in park units through a suite of national and local programs.

As of 2017, there were over 1.4 million acres of national park units infested with invasive plants, of which only approximately 43,000 acres are controlled, in which invasive plant infestations have been reduced to a level that can be maintained by park staff.

"Most Wanted" Invasive Plant Species

Highlighted invasive species of concern

While there are many species of plants that are wreaking havoc in national parks, some are particularly destructive. Learn more about several of these below.

Kudzu engulfing a forest's native vegetation.

NPS Photo.

Kudzu

Kudzu, also known as “The Vine That Ate the South,” grows 35-100 feet long and posses fleshy taproots that can grow to nine feet deep in the ground. Its leaves are alternate on the stem and are hairy underneath.

Flowering occurs in midsummer, with long, purple, fragrant flowers that hang in clusters in the axils of the leaves. Kudzu can turn its leaves in relation to the sun to take full advantage of available light or to reduce exposure to sun thus reducing water loss.The vines must be removed to allow native vegetation to thrive once again.

Cheatgrass has been taking over the western landscapes of the U.S.

Photo courtesy of Jennifer Strickland/U.S. Fish and Wildlife Service.

Cheatgrass

In the 1940s, Aldo Leopold warned this invasive plant posed a grave threat to western U.S. habitats. Since then, it has spread and spread. This annual grass arrived in shipments of European wheat during the late 1800s, and quickly established itself in many areas occupied by native plants like sagebrush.

Cheatgrass is well adapted to dry climates and can out-compete many native plants. The barbed bristles of the plants penetrate or adhere readily to clothing and fur. Cheatgrass alters regional fire regimes - meaning it causes increased fire size, duration, and intensity. This impacts native species that are not well adapted to these changes.

Tamarisk spread through the west and caused major changes to natural environments.

NPS Photo.

Tamarisk

Tamarisk - also known as salt cedar - is a dense shrub that causes all sorts of trouble in the Western U.S. but also infests areas in the eastern part of the country. As of 1963, tamarisk has dominated riparian zone species along the Colorado River, beating native species to water with their long taproots.

In addition, these invasive plants, alter soil salinity, increase fire frequency, and displace the native vegetation- thus displacing native animals as well.

Invasive Plant Species Management in National Parks

Invasive species continue to be introduced and found in new places. Several highly invasive and destructive species have been successfully eradicated from parks lands, but work continues every day.

The NPS has dedicated significant resources towards invasive plant species management in parks, with the support of national and regional level offices. The Invasive Plant Program, based in Fort Collins, Colorado, and individual parks fund and support 17 Exotic Plant Management Teams to provide "boots-on-the-ground" in the fight against invasive species. Learn more about the Servicewide program by visiting their website, here.

Learn more about invasive species management in parks under What We Do