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What are Invasive Species? Why Should we Care? 

It's a question we get asked all the time, and it's totally fair to ask! We encourage all questions regarding invasive species, and if you have any that aren't answered below feel free to contact our engagement and education specialist, Katie, directly here

Typically, invasive species have distinct advantages over native species. Once they have established a presence, it can be very difficult to eradicate invasive species populations. There are several ways in which invasive species can cause harm to an area:

Native Species: invasive species are often immune to natural predators, climatic factors, and other ecological controls that keep native species in check. This advantage helps them to displace native species and reduce biodiversity.

Local example: Purple Loosestrife forms dense monocultures in our wetlands inhibiting native species' ability to grow thereby reducing food sources for animals. 

Photo: Eric Coombs, Oregon Department of Agriculture,


Human health: in addition to being a nuisance, some invasive species can also introduce diseases and physical dangers to people.

Local example: Wild Parsnip stems, leaves, and flowers contain chemicals that can increase skin sensitivity to sunlight and cause severe rash or blistering. 


Recreational Opportunities: invasive species can impact fish populations, make beaches/lakes undesirable for swimming, and impact shoreline views for homeowners. 

Local example: Invasive phragmites form dense monocultures - can you believe there's a lake behind all the phragmites in this picture?


Economic Prosperity: the introduction of invasive species often decimates populations of competing native species, which in turn limits natural resource supplies tied to tourism. 

Local example: Fish that feed on native invertebrates like mayflies and caddisflies may find it more difficult to forage in rivers invaded by New Zealand mudsnails. Fish will consume New Zealand mudsnails, but due to the snail’s thick shell, equipped with a tightly closing “hatch”, they are difficult for fish to digest, offer the fish little nutritional value and can be excreted alive.

Image by Sara Kurfeß
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