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Environmental and Ecological Impacts

Invasive species can impact both the native species living within an ecosystem as well as the ecosystem itself.

Native species populations can be directly affected through predation, herbivory, and disease (Simberloff 2013). For example, the brown tree snake (Boiga irregularis) caused the extirpation of nine species of bird on Guam, and the hemlock woolly adelgid (Adelges tsugae) has caused widespread mortality of eastern hemlock trees by feeding on its sap (Simerloff and Rejmánek 2011).

Indirectly, invasive species may cause native species declines due to resource competition and habitat alteration (Davis 2009). For instance, plant invasions have been demonstrated to alter carbon and nitrogen cycles and fire regimes in invaded ecosystems (Simerloff and Rejmánek 2011). The invasion of downy brome (Bromus tectorum) in Western U.S. grasslands has led to an increase in the frequency and intensity of wildfires (Simerloff and Rejmánek 2011), and saltcedar (Tamarix spp.) makes the soil inhospitable to native species by depositing large amounts of salt into the surrounding soil (Bell et al. 2002).

See also: General Invasive Species Impacts


  • Invasive Species and Climate Change Impact Coastal Estuaries

    • May 5, 2022
    • University of California, Davis.

    • Native species in California's estuaries are expected to experience greater declines as invasive species interact with climate change, according to a study from the University of California, Davis. The study, published in the Ecological Society of America's journal, Ecology, said these declines are expected not only because of climate-related stressors, but also because of the expanding influence of new invasive predators whose impacts are occurring much farther up the estuary.

  • Invasive Species Are Taking Over Ohio Forests

    • Jun 15, 2022
    • University of Cincinnati.

    • A new botanical survey of southwest Ohio found that invasive species introduced to the United States over the past century are crowding out many native plants. Biologists from the University of Cincinnati are retracing two exhaustive surveys conducted 100 years apart to see how the Queen City's plant diversity has changed over the past two centuries. They focused their attention on undeveloped parts of cemeteries, banks of the Mill Creek and public parks that have remained protected from development during the last 200 years. The study, titled "The rise of nonnative plants in wooded natural areas in southwestern Ohio," was published in June in the journal Ecological Restoration.

  • Invasive Species Bullfrog and Snake Cost World $16bn - Study

    • Jul 29, 2022
    • BBC News.

    • Scientists tallying the economic damage wrought by invasive pests across the world found two species are responsible for more harm than any other.

      The American bullfrog and brown tree snake have collectively caused $16.3bn in global damage since 1986. In addition to ecological harm, the invasive pair have ruined farm crops and triggered costly power outages.

  • New Study by UM Biological Station and USGS Researchers Reveals How Invasive Species Affect Native Food Webs

    • Nov 1, 2021
    • University of Montana. Flathead Lake Biological Station.

    • Invasive species cause biodiversity loss and about $120 billion in annual damages in the U.S. alone. Despite plentiful evidence showing that invasive species can change food webs, how invaders disrupt food webs and native species through time has remained unclear. Now, thanks to a collaborative study conducted by researchers representing the University of Montana's Flathead Lake Biological Station (FLBS), U.S. Geological Survey (USGS), and Montana Fish, Wildlife & Parks, there is new insight into how invasive species progressively affect native food webs.

  • IUCN Standard to Support Global Action on Invasive Alien Species

    • Sep 2020
    • International Union for the Conservation of Nature.

    • IUCN has launched a global standard for classifying the severity and type of impacts caused by alien species, known as the Environmental Impact Classification for Alien Taxa (EICAT). This tool will alert scientists, conservation practitioners and policy makers to the potential consequences of invasive alien species, guiding the development of prevention and mitigation measures.

Selected Resources

The section below contains highly relevant resources for this subject, organized by source.

Council or Task Force
  • Why Should I Care?

    • Georgia Invasive Species Task Force.

    • Invasive species spread either accidental or intentional into new environments has resulted in negative impacts to the ecological communities of infested areas, to commercial, agricultural, aquacultural, and recreational activities dependent on these areas.

Federal Government
State and Local Government


  • Bell, C.E., B. Neill, J.M. DiTomaso, et al. 2002. Saltcedar: a non-native invasive plant in the Western U.S. (PDF | 505 KB) University of California, Weed Research & Information Center. WRIC Leaflet #02-2.
  • Davis, M.A. 2009. “Impacts of invasions.” In: Invasion Biology. Oxford: Oxford University Press.
  • Simberloff, D., and M. Rejmánek, eds. 2011. Encyclopedia of Biological Invasions. Berkeley, Calif.: University of California Press.
  • Simberloff, D. 2013. Invasive Species: What Everyone Needs to Know. New York: Oxford University Press.