Impacts of Invasive Plants

Facts and Figures | In the West | Economic | Ecological | Wildlife

Invasive Weed Impact Calculator: An easy-to-use website to help managers decide whether or not to use costly weed control measures to battle leafy spurge/spotted knapweed. Developed through MSU-Extension and USDA-ARS.

Facts and Figures

Economic and Ecological Costs Associated with Aquatic Invasive Species, D. Pimentel.
Proceedings of the Aquatic Invaders of the Delaware Estuary Symposium, Malvern, Pennsylvania, May 20, 2003, pp. 3-5.

Economic Impacts of Aquatic Invasive Species, published Jan. 14, 2005, by the National Center for Environmental Economics of the EPA.

Environmental and Economic Costs Associated with Non-Indigenous Species in the United States. David Pimentel, et al., Cornell University, June 12, 1999

Facts and Figures from the Global Invasive Species Programme — a searchable archive

How Do Weeds Affect Us All? K.G. Beck, Associate Professor of Weed Science, Colorado State University, Ft. Collins, Colorado.

The Invasive Species Challenge in Estuarine and Coastal Environments: Marrying Management and Science. Includes details of economic impacts. From Estuaries and Coasts, Journal of the Coastal and Estuarine Research Federation

Invasive Species Definition Clarification and Guidance White Paper. Submitted by the Definitions Subcommittee of the Invasive Species Advisory Committee (ISAC). Discusses many types of impacts of invasive species, including impacts to human values, recreation, and more.

Invasive Species Impact Ranks for the United States: Summary of Results as of January 10, 2005 (Excel: 92K), from NatureServe.

Weed Fact Book from Federal Interagency Committee for the Management of Noxious and Exotic Weeds, 1998. Westbrooks, Randy G.,..Invasive plants: changing the landscape of America: fact book.

In the West

Noxious Weeds: Impacting Washington's Resources

USFS Invasive Plant Regional Environmental Impact Statement (EIS) for Region 6 (Washington and Oregon) on invasive plants. Comprehensive coverage of invasive plants, as well as the economic costs and projections of different control methods and potential costs of delaying management efforts.

What Is So Dangerous About the Impacts of Noxious Weeds on the Ecology and Economy of Montana? MSU Bozeman Extension Publications, Bulletin No. 152 (1998). This pamphlet provides a very concise but thorough justification for making every possible effort to manage noxious weeds. It stresses costs not only to agriculture but to recreation and wildlife. Full color, free from MSU Extension.

Weed Impacts from Weeds BC

Why Weeds Are Bad from Larimer County, Colorado, Weed District

Economic Impacts

An Annotated Bibliography on the Economics of Invasive Plants from University of California-Davis Agricultural Issues Center.

The Economic Costs of Delaying Invasive Weed Control: An Illustration based on Nevada’s Tall Whitetop Initiative — Special Publication SP 01-08, University of Nevada-Reno Cooperative Extension

Economic Effects of Invasive Weeds on Land Values (from an Agricultural Banker's Standpoint)

Economic Impacts of Aquatic Invasive Species, published January 14, 2005, by the National Center for Environmental Economics of the EPA.

Economic Impact of Aquatic Weeds: Literature Review (pdf). Available through the Aquatics Ecosystem Restoration Foundation handobook, Best Management Practices for Aquatic Plant Management

Economic Dimensions of Invasive Species — from June 2003 issue of CHOICES, the magazine of Food, Farm, and Resource Issues, published by the American Agricultural Economics Association

Economic Impacts from National Invasive Species Information Center. Many links to a variety of national and international sources, many species, a variety of industries, and more.

The economics of biological invasions. Perrings C., M. Williamson, S. Dalmazonne eds. 2000. Edward Elgar Publishers (introductory chapter)

The Estimated Costs of Treating Invasive Weeds in Elko County, Nevada (pdf) — Fact Sheet FS-03-41, University of Nevada-Reno Cooperative Extension

Estimating Net Losses in Recreation Use Values from Non-Indigenous Invasive Weeds (pdf) — Special Publication SP-03-10, University of Nevada-Reno Cooperative Extension

Evaluating Montana’s Dyer’s Woad (Isatis tinctoria) Cooperative Eradication Project
Monica L. Pokorny and Jane M. Krueger-Mangold, Weed Technology 2007, 21:262–269. Analysis of cost savings in Montana of Dyer's woad eradication project.

Invasive Plants of Range and Wildlands and Their Environmental, Economic, and Societal Impacts Provides comprehensive information on the acreage infested, rate of spread and damage caused by sixteen important invasive plant species. Order from the Weed Science Society of America website; click on "book" in left panel.

National Economic Impacts of invasive species from Invasivespecies.gov, the gateway to Federal efforts concerning invasive species.

New Strategies for Weed Prevention from Exotic Pests of Eastern Forests Conference Proceedings. Posted by www.invasive.org. Covers economic impact of weeds; regulatory strategies; weed detection at ports of entry; bibliography.

Summary of a Survey of Literature on the Economic Impact of Aquatic Weeds from the Aquatic Ecosystem Restoration Foundation.

Ecological Impacts

Ecological Impacts of Exotic Invasive Species — discusses saltcedar in particular

Environmental Impacts of Marine Exotics from ActionBioscience.org. Discusses eel grass, spartina, and others.

Impacts of Alien Plants on Hawai'i's Native Biota, from Hawaiian Alien Plant Studies, University of Hawaii Botany Department

Impacts of invasive aquatic species from Habitattitude: Do Not Release Fish and Aquatic Plants

Invasive Plants of Range and Wildlands and Their Environmental, Economic, and Societal Impacts Provides comprehensive information on the acreage infested, rate of spread and damage caused by sixteen important invasive plant species. Order from the Weed Science Society of America website; click on "book" in left panel.

The Western Ecological Research Center conducts research to improve the ability to detect, monitor, and predict the effects of invasive species.

Impacts on Wildlife

Impacts on Game Fish by Aquatic Nuisance Species from Protect Your Waters.

From RefugeNet, the site of the National Wildlife Refuge Association, America's Silent Killer: How Invasive Species Threaten America's Unique Wildlife Heritage

CIPM has developed a selected bibliography of eleven articles describing or quantifying impacts of invasive plants on wildlife. All the articles are of general interest, but information on specific topics can be found in the references below, as follows:

Selected Bibliography

  1. Silent Invasion: A Call to Action from the National Wildlife Refuge Association. October 2002, 17 pp.
    • Across all 50 states, invasive plants have filled more than 100 million acres (p. 4).
    • They continue to spread at an annual rate of approximately 14 million acres (p. 4).
    • Nearly 8 million acres of habitat distributed among half the national wildlife refuges across the country are infested by at least 675 different invasive species (p. 5).
    • In Willapa National Wildlife Refuge in Washington, Spartina grass, a non-native cordgrass is making mudflats and saltmarshes inhospitable to birds (p. 9). This refuge is a key stopover for shorebirds migrating along the Pacific flyway. In some places on the refuge, Spartina is doubling its range every year (p. 9).
    • Purple loosestrife infests 400,000 acres of federal wetlands, marshes, pastures and riparian meadows in every state except Florida. It crowds out higher quality nutrition of wildlife, reduces aquatic habitat value and wipes out endangered species, i.e. the orchid (p. 10).
    • Phragmites is an aggressive plant that out competes and eliminates other marsh species to form large, impenetrable stands that can be detrimental to waterfowl (p. 10).
    • The Attwater Prairie Chicken National Wildlife Refuge in Texas is besieged by Chinese tallow and McCartney rose. These two invasive species combined shade out native grasses that the prairie chicken needs for survival (p. 16).
  1. Cheater, Mark. 1992. Alien Invasion: They’re green, they’re mean, and they may be taking over a park or preserve near you. Nature Conservancy Magazine Sept./Oct. 1992, pp. 24-29.
    • Water hyacinth, with leaves that stretch nearly a yard above the water and a large net of submerged roots, is one of the most troublesome aquatic weeds in the Gulf Coast (p. 26).
    • It crowds out other plants, prevents migratory birds from landing, and chokes out fish, completely transforming wetlands (p. 26).
    • One flowering stem of Canada thistle can produce as many as 40,000 seeds, which can lie in the ground for 20 years and still germinate (p. 29).
    • Canada Thistle is wiping out the Colorado butterfly plant in Wyoming. (p. 26).
  1. Schmitz, Don C. and Daniel Simberloff. 1997. Biological Invasions: A Growing Threat Issues in Science and Technology Online, Summer 1997.
    • Exotic species have contributed to the decline of 42% of U.S. endangered and threatened species (4).
    • At least 3 of the 24 known extinctions of species listed under the Endangered Species Act were wholly or partially caused by hybridization between closely related exotic and native species (4).
    • Introduced species are the second greatest cause of species endangerment and decline worldwide (4).
    • Spread of fire-adapted exotic plants that burn easily increases frequency and severity of fires, to the detriment of property, human safety and native flora and fauna (6).
    • Approximately ΒΌ of U.S. agricultural gross national product is lost to foreign plant invaders and the costs of controlling them (5).
    • Foreign weeds spread on BLM lands at over 2,300 acres per day and on all western public lands at twice that rate (5).
  1. DiTomaso, Joseph M. 2000. Invasive weeds in Rangelands: Species, Impacts and Management. Weed Science 48:255-265.
    • Weeds impact wildlife habitat and forage, deplete soil and water resources, and reduce plant and animal diversity (p. 255).
    • In C. maculosa-infested range, Rocky Mountain Elk use was reduced by 98% compared with bunchgrass-dominated sites (p. 257, Sheley, 1998).
    • When C. maculosa was removed from a historic elk winter range in western Montana, elk use increased dramatically (p. 257; Thompson, 1996).
    • E. esula has been shown to significantly impact forage value for bison, deer and elk in Theodore Roosevelt National Park in North Dakota (p. 257; Trammell and Butler, 1995).
    • Bison and deer use of E. esula-infested areas was 83% and 70% less than non-infested sites, respectively (p. 257).
  1. Pimentel, David, Lori Lach, Rodolfo Zuniga, and Doug Morrison. Environmental and Economic Costs Associated with Non-Indigenous Species in the United States.
    • Purple Loosestrife:
      • Spreading at a rate of 115,000 ha/year.
      • Reduced the biomass of 44 native plants.
      • Endangers wildlife that depend on native plants (5).
    • Estimated 138 non-indigenous tree and shrub species have invaded native forest and shrub ecosystems.
    • Some trees have caused displacement of native trees, shrubs and other vegetation types, which in turn has reduced populations of some associated native animal species (10).
    • In Florida, aquatic plants, hydrilla, water hyacinth, and water lettuce, are altering aquatic habitats.
      • Alter fish and other aquatic animal species, choking waterways, altering nutrient cycles, and reducing recreational use of rivers and lakes (11).
    • European Cheatgrass
      • Changes the vegetation and fauna of natural ecosystems.
      • Invaded and spread throughout the shrub-steppe habitat of the Great Basin in Idaho and Utah and predisposed the invaded habitat to fires.
      • Before cheatgrass invasion, fires burned once every 60 to 110 years; after invasion, fires burn every 3 to 5 years (9).
  1. USGA – Northern Prairie Wildlife Research Center. Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria) in North American Wetlands: Impact of Lythrum salicaria on wetland habitats and wildlife.
    • Montezuma National Wildlife Refuge, New York
      • By 1978, L. salicaria occupied about half the forage area of Canada geese.
      • Goslings became more vulnerable to their principal predator, the red fox, hiding in purple loosestrife
    • Black Tern
      • Declining in numbers in Wisconsin (Faanes, 1979) from habitat loss due to L. salicaria.
      • Invasion of shallow pond borders by L. salicaria will probably render typical black tern nest sites unusable (p. 5).
    • Sandhill Crane
      • Thousands of ha that were formerly emergent aquatic vegetation are now overgrown with woody vegetation and unattractive to sandhill cranes (USFWS, 1981; p. 7).
      • “In the wildlife marsh, with average water depths of 12 to 18 inches, purple loosestrife can take over and occupy much water area that should be occupied by waterfowl food plants (Smith, 1964).”
  1. Simberloff, Daniel. 1996. Impacts of Introduced Species in the United States. Consequences 2 (2).
    • In western rangelands, alien plants affect more than 16 million acres, at great cost to cattle raising. 2,300 additional acres are invaded each day (p. 11).
    • Of the 632 species and subspecies recently officially listed as “endangered” under the Endangered Species Act, 45 are primarily threatened by competition from introduced species (p. 11).
    • For 424 of the 632 species, habitat destruction is the main threat, but the nature of the threat for many of the plants that are included is the domination of their new habitat by introduced species (p. 11).
  1. Leitch, Jay A., F. Larry Leistritz, Dean A. Bangsund. 1996. Economic Effect of Leafy Spurge in the Upper Great Plains: Methods, Models, and Results. Impact Assessment 14, Dec. 1996.
    • Leafy spurge expansion leads to a decline in native plants, and the reduction in plant diversity can reduce wildlife habitat and may increase water runoff and soil erosion (p. 425).
  1. "Wildlife, Plant Communities, and Biodiversity." From Randy G. Westbrooks. Invasive Plants, Changing the Landscape of America, the Fact Book, Federal Interagency Committee for the Management of Noxious and Exotic Weeds, Washington D.C., 1998. (Copies are available from the U.S. Government Printing Office. Call (202) 512-1800 to order.)
    • Invasive plants degrade wildlife habitat
      • In Arizona, Lehmann lovegrass stands support fewer small mammals, seed-harvesting ants, and quail than non-infected areas (Lee Otteni, BLM, Farmington, New Mexico, 1996)
      • Invasive plants affect big game species by crowding out native forage.
      • Non-native plants replace native plants that are preferred as forage by big game species and as habitat by smaller wildlife species.
    • Invasive plants reduce available winter forage for wildlife.
      • Spotted knapweed invasion of bunchgrass sites in Western Montana reduces available winter forage for elk as much as 50% to 90%.
      • Forage loss from spotted knapweed can be as high as 1,620 pounds per acre (Duncan, 1997).
      • In the Disappointment Creek area north of Delores, Colorado, the invasion of Russian knapweed has drastically reduced the availability of key winter range for wildlife (Goold 1994).
    • Control of invasive plants increases forage for wildlife species.
      • The use of herbicides to remove spotted knapweed from an elk winter range in Montana resulted in a 266% increase in the use of the area by elk (Duncan, 1997).
  1. Zavaleta, Erika. 2000. Valuing Ecosystem Service Lost to Tamarix Invasion in the United States. Invasive Species in a Changing World. Island Press, Washington D.C.
    • Three federally listed and one candidate for federal listing suffer clear, quantifiable negative impacts from Tamarix invasion (p. 278).
      • The southwestern willow flycatcher suffers displacement of riparian forest habitat due to Tamarix
      • The bald eagle suffers loss of roosting and nesting sites due to Tamarix
      • The whooping crane suffers encroachment of Tamarix into marsh habitat
      • The peninsula bighorn sheep suffers drying of desert springs due to Tamarix
    • Bird densities, diversity and individual health are greatly reduced in Tamarix stands compared to native vegetation.
      • Total avian abundances in Tamarix on the lower Colorado River range seasonally from 39% to 59% of those found in native willow, cottonwood, and mesquite habitats.
      • Willow flycatchers, of which the southwestern subspecies is federally endangered, were found to be both more scarce and lower in individual body mass and fat stores in Tamarix stands than in cottonwood habitats on the Rio Grande.
  1. Raloff, Janet. 1998. Botanical ‘velcro’ entraps hummingbirds. Science News Oct. 17, 1998.
    • Small birds like hummingbirds get trapped in burdock (2).
    • Martin K. McNicholl, a consulting ornithologist in Burnaby, BC, has evidence indicating that burdock sporadically claims the lives of small birds and brown bats (7).

 


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Updated 12/12/07