Are you using a screen reader? Click here to view the navigation links for this site as a bulleted list.

Partner logos: BLM, FWS, FS, NPS, University of Montana Logo
Connecting federal employees, scientists, educators, and the public with their wilderness heritage
Text size: A | A | A  [Print]

Threats to Wilderness From Invasive Species and Disease

Closeup of a whitebark pine infected with white pain blister rust fungus.
The Whitebark Pine Ecosystem Foundation[3] estimates that 98% of the range of whitebark pine in the United States is on public lands. White pine blister rust, a fungus unintentionally brought from Eurasia about 1900, has spread throughout the range of whitebark pine, and mortality from the combination of blister rust and mountain pine beetle can exceed 50%.
In the United States, 42% of the species on the Threatened or Endangered species lists are threatened by invasive species--plants, animals, insects, fungi and pathogens that do not normally live along side native species[1]. In a 2001 survey of Fish and Wildlife Service wilderness areas, invasive plants were considered a major problem in 26% of wilderness areas in the lower 48 states, and exotic animals were deemed one of the top ten management priorities in 32% of the wilderness areas surveyed[2].

In many cases, invasive species were brought to the United States for food, fiber, as game or fur, or as ornamentals, then spread into natural areas. For example, Buffelgrass, a hearty, drought-tolerant grass, was introduced in the desert southwest in the 1930's as livestock forage. Later it was used for erosion control and soil stabilization. Today, however, its rapid spread has converted fire-resistant desert into flammable grassland, threatening Saguaro Cacti and other desert species[4]. Although Arctic foxes are native to Alaska's mainland, they were introduced for fur farming between 1750 and 1950 on more than 450 islands, where they threaten native seabirds by stealing eggs[5].

Although some invasive species were introduced intentionally, others were accidentally or unintentionally. Norway rats, which escaped from ships and also endanger Alaska's island-nesting seabird populations.

Sometimes invasive species simply coexist with natives, but more often they disrupt entire ecosystems by outcompeting, displacing, sickening, or prety upon native species or interbreeding with native species causing hybridization[6]. For example, intentional stocking of non-native shrimp in the early 1970's caused a series of changes in lakes, eventually displacing nesting Bald Eagles[7]. In these cases, the effects of invasive species introduction are widespread with invasives altering overall species distribution and composition, nutrient cycling and successional pathways. In addition to the ecological costs of invasive species, the economic damage and control costs from invasive species have been estimated at nearly $137 billion per year[1].

Invasive Species Control

Hiking boots.
Since the seeds of invasive plants can easily get transported in mud and dirt, always remember to clean the dirt out of your hiking boots or off of your vehicle before you leave an area.
Invasive species can be erradicated through physical, biological, or chemical means, and the wilderness management agencies are responsible for most monitoring and control programs. Overall, in the 2001 survey of Fish and Wildlife Service wildernesses, control programs for invasive plants exist in 27% of the wilderness areas, for exotic animals in 21%, and for exotic pathogens in 3%[2]. Volunteers are increasingly being used to conduct invasive species monitoring and erradication, however. For example, in 2005 Wilderness Institute Citizen Science Program[8] volunteers helped map 350 weed infestations in Montana wilderness areas. Other volunteer organizations work with the agencies or county extension offices to organize weed pulls.

Prevention, however, is often the best way to protect wilderness from invasive species. Prevention often includes educating wilderness visitors about invasive species, often using posters or other trailhead information materials. Generally, the National Invasive Species Information Center and Council recommend the following ways you can help prevent the spread of invasive species:

  • Learn what invasive species are in your area and what is being done about them.
  • Report new invasive species and range expansions.
  • Share your knowledge.
  • Clean hiking boots, waders, boats and trailers, off-road vehicles, and other pathways of spread to stop hitchhiking invasive species.
  • Use certified "weed-free" forage, firewood, hay, mulch, and soil.
  • Don't dump live bait into waterways.
  • Remove invasive plants from your land.
  • Plant non-invasive plants in your garden.
  • Volunteer for organized efforts to remove invasive species from natural areas.
  • Care for aquarium fish and other pets properly so that they don't become invasive.
  • Ask your political representatives to support invasive species efforts.
  • Write a letter about invasive species to your newspaper.
  • Support non-profit organizations that work with invasive species.


  1. Pimentel, D.; R. Zuniga and D., Morrison (2005). Update on the Environmental and Economic Costs Associated with Alien-Invasive Species in the United States. Ecological Economics, 52, 273–288
  2. Temple, D. J., Cilimburg, A. B. & Wright, V. (2004). The Status and Management of Exotic and Invasive Species in National Wildlife Refuge Wilderness Areas. Natural Areas Journal, 24(4), 300-306. Retrieved on December 14, 2009.
  3. Whitebark Pine Ecosystem Foundation. (n.d.). Whitebark Pine Ecosystem Foundation - Threats. Retrieved on December 8, 2009.
  4. Buffelgrass Information Center. (2008). Retrieved on December 14, 2009.
  5. Sims, G. (1996). The Paradox of the Arctic Fox. National Wildlife Magazine, 34(2). Retrieved on December 14, 2009.
  6. Cole, D. N. & Landres, P. (1996). Threats to Wilderness Ecosystems: Impacts and Research Needs. Ecological Applications, 6(1), 168-184.
  7. Spencer, C. N., McClelland, B. R. & Sanford, J. A. (1991). Shrimp Stocking, Salmon Collapse, and Eagle Displacement: Cascading Interactions in the Food Web of a Large Aquatic Ecosystem. BioScience, 41(1), 14-20.
  8. Wilderness Institute. (n.d.). Citizen Science. Retrieved on December 16, 2009.

Give us your feedback