Invasive Species

A Threat to Forest Health

Find out how to identify and address non-native flora and fauna.

About Invasive Species

Flowering knapweed

Invasive species are a serious worldwide threat to natural resources. Invasive species means, with regard to a particular ecosystem, a non-native organism whose introduction causes or is likely to cause economic or environmental harm, or harm to human, animal, or plant health (from Executive Order 13112, as amended – Safeguarding the Nation from the Impacts of Invasive Species, signed Dec. 5, 2016). E.O. 13112 requires Federal agencies to prevent and control these species and to minimize their economic, ecological, and human health impacts. Environmental and economic costs caused by invasive species in the U.S. alone were estimated by Pimentel et al. (2005) to exceed $120 billion per year. 1

Invasive Species in Region 3

Invasive species threatening Region 3 range from disease pathogens to mammals (see list of invasive species by national forest). The U.S. Forest Service has developed a number of regional documents for invasive species management and pesticide use in Region 3.

Specific information on invasive species affecting national forests and grasslands in Region 3 may be found below.

  • Plants

    Flowering Malta starthistle

    Invasive plants can spread rapidly and threaten native ecosystems.

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  • Animals

    Two feral hogs and piglets

    Terrestrial invasive animals can impact native vegetation, wildlife, and fish.

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  • Aquatic Species

    Quagga mussles

    Aquatic invasive plants, fish, and other aquatic invasive organisms can displace and out-compete native species in waterways.

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  • Diseases Affecting Fish & Wildlife

    Bats with white noses, evidence of white-nose syndrome

    A number of diseases affect specific species of fish and wildlife, including white-nose syndrome in bats.

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  • Insects & Diseases Affecting Trees

    Emerald Ash Borer

    Several invasive tree diseases are currently impacting forests in the Southwest. 

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  • Weeds in the Wilderness

    Wilderness Volunteers

    There are a number of invasive weeds currently affecting wilderness areas in the Southwest. 

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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. Ecol. Econ. 52(3):273-288.