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Learn about Invasives

What is an Invasive Species?

An Invasive Species is one that is non-native to the ecosystem under consideration and whose introduction causes, or is likely to cause, economic or environmental harm, or harm to human health. Invasive species may be plants, animals, or pathogens.

Economic Impacts:  reduced agricultural yield, decreased fisheries health, loss of recreation opportunities, decrease in wood/forest products, disrupted trade, decrease in tourism and rising management costs

Environmental Impacts:  decrease in biodiversity and structural diversity, disruption of natural processes, reduced ecosystem function and services

Human Health Impacts:  Human injury or illness, decreased soil, air, and water quality, climate and other weather changes, altered flood regimes



Native:  Any species that is part of a natural ecosystem or habitat within an ecosystem – often associated with a historical timeframe such as prior to European Settlement within North America

Non-Native:  Any species that is not a natural part of a specific ecosystem or habitat

Exotic:  Most often refers to species from ‘far away’, such as another continent

Invasive Species:  Non-native species that causes, or is likely to cause, economic or environmental harm, or harm to human health

Weed and or Pest:  Any species, anyone doesn’t like…for any reason


Why are Some Species Invasive?

Species may become established for a number of reasons. Often, this is due to the lack of a natural predator, parasite, or pathogen that allows them to outcompete native species. They may also fill an ecological niche that was vacant before they arrived, such as an ability to take advantage of early or late season growth. Invasive species often have a high reproductive rate, reach maturity early, disperse rapidly, and/or have a broad tolerance range to environmental conditions. Invasive species are also associated with humans and forms of human disturbance.

Pathways of Invasion

Pathways of Invasion are the means by which invasive species are becoming established and are transported from one location to another.

Natural Pathways:  Means of natural dispersion of species such as seed dispersal mechanisms or species specific adaptations for movement. Natural pathways include wind, water/currents, weather events and flight.

Assisted (Man-Made) Pathways:  Assisted pathways are enhanced or created by human activity. Introduction and establishment of invasive species through man-made pathways may be considered as intentional or unintentional

Intentional: Landscape and Nursery Trades, bait dumping, exotic pet release, agricultural commodities

Unintentional: Soil disturbance and construction, shipping,  transportation of species on vehicles, boats, equipment and/or clothing, hitchhikers on imports, mowing, ballast water discharge


For more information on Invasive Species, please see our Resources and Invasive Species Profiles