Sunday, January 19, 2014

So you slept through science class part 10–What’s an “invasive non-native”?

In previous posts we’ve talked about ecosystems and the role that each species plays in an ecosystem.  Over thousands of years, species in an ecosystem evolve together.   An example of this “co-evolution” would be insects that begin to come out of winter sleep at about the same time that flowers begin to bloom – this coordination ensures that the insects get nectar for food and that the plants get pollination.   When these native species evolve together, this type of coordination helps the ecosystem to remain healthy. 

Sometimes, new species that didn’t evolve in the ecosystem are introduced.  These species would be considered non-native.  Here in the Chesapeake Bay region, we often consider any species that was introduced after Europeans arrived in the area (let’s say the 1600s) to be a non-native.  Some non-natives stay where they’re planted and really don’t cause much trouble – plants such as roses, tomatoes, or tulips are non-natives.  Sure, non-native species may not be the greenest option, since they require more water or fertilizer than natives, but they aren’t quite the problem that their cousins the “non-native invasive” are.

Non-native invasive species are plants or animals that are introduced into an ecosystem and quickly begin to outcompete native species.  They may be a predator that eats everything in sight, such as the northern snakehead (photo credit Virginia Department of Game and Inland fisheries), or they could be a plant that outcompetes and kills other plants in the area (check your backyard for English ivy…).  Common non-native invasives include house sparrows and kudzu, but there are many, many more.  And these species aren’t just an ecological nuisance, they can have major economic impacts too.  Kudzu can costs homeowners substantial amounts once it gets into their landscaping (think herbicides).   Zebra mussels were first introduced in the Great Lakes region, but have spread throughout the U.S.  The Missouri Department of Conservation estimates that this small mollusk, responsible for clogging water intake pipes and power plant pipes, fouling boat hulls, and displacing native species, will cost the U.S. billions of dollars by the end of this decade.  Another species that has the potential to do serious economic damage is the emerald ash borer, which kills ash trees.  If you like baseball, you should be concerned, because wood baseball bats are made from ash.  Check out this video about the tiny invader:   Good news though,  birds may be helping with reducing this insect species.

So how can a greenmomster help?  There are two easy ways to be part of the solution.  Since one of the best ways to limit the negative effects of non-natives is to prevent their establishment in new ecosystems, greenmomsters can:

  1. Try to choose native plants for landscaping
  2. Never set an unwanted pet (such as a snake) loose into the environment.  Check with a local nature center for proper ways to find them new homes.



Conservation Commission of Missouri.  2014.  “Zebra Mussel Control” Missouri Department of Conservation website.  Accessed 1/19/2014 at

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