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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.

  • 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.

  • NOAA Researchers Model Risk of Asian Carp Invasion in Lake Huron

    • Apr 30, 2020
    • DOC. National Oceanic and Atmospheric Administration.

    • New research by NOAA and partners finds that two species of invasive Asian carp -- the bighead carp and silver carp, collectively known as bigheaded carps -- could be capable of establishing populations in Saginaw Bay, Lake Huron and affecting the health of ecologically and economically important fish species such as yellow perch. The research, appearing online in the journal Biological Invasions, is based on a new model that simulates interactions between the bigheaded carps and a range of fish species, including walleye, yellow perch, and groups lower on the food web over a time period of 50 years. Over 180 non-indigenous aquatic species have already become established in the Great Lakes, with a handful of these producing substantial negative impacts. While bigheaded carps are established in watersheds near the Great Lakes, they have not yet become established in the Great Lakes.

  • Environmental Protection and Plant Health: A New IPPC Factsheet Explains the Link

    • Feb 2019
    • UNFAO. International Plant Protection Convention.

    • You cannot protect the environment without also safeguarding plant health. When plant pests and diseases spread into new areas they seriously damage entire ecosystems, putting at risk biological diversity and the environment itself. Tiny and lethal at the same time, plant pests and invasive alien species have been recently identified as the main driver of biodiversity loss. Pests are also responsible for losses of up to USD 220 billion in agricultural trade each year and the loss of 40 percent of the global food crop production. Climate change is making the situation even worse. It is changing the life cycle of pests – sometimes increasing the number of yearly generations - and creating new niches where they can thrive. For more information see the IPPC factsheet "Plant Health and Environmental Protection (PDF | 1.22 MB)".

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
  • Invasive Predators and Global Biodiversity Loss

    • 2016
    • Proceedings of the National Academy of Sciences.

    • Doherty, T.S., A.S. Glen, D.G. Nimmo, E.G. Ritchie, and C.R. Dickman. 2016. Invasive predators and global biodiversity loss. Proceedings of the National Academy of Sciences 113(40):11261-11265.

  • Invasive Species and Fire in California Ecosystems [PDF | 227 KB]

    • 2010
    • California Native Plant Society.

    • In Fremontia, the journal of the California Native Plant Society.

  • Invasive Species and Species at Risk

    • Invasive Species Centre (Ontario).

    • Protecting ecosystems from degradation caused by invasive species can help protect species at risk and critical habitats. In 2019, the United Nations reported invasive alien species as a top-5 driver of species decline.

  • Invasive Species and Species at Risk

    • Invasive Species Centre (Ontario).

    • Protecting ecosystems from degradation caused by invasive species can help protect species at risk and critical habitats. In 2019, the United Nations reported invasive alien species as a top-5 driver of species decline.



  • 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.