There are more recognition days, or weeks, these days than you can shake a stick at. Some highlight worthy causes, such National Arbor Day (April 29), and National Girl Scout Day (March 12). Some you scratch your head at, like National Cheese Doodle Day (March 5) and National Talk Like a Pirate Day (Sept. 19, aaarrr!). One you probably haven’t heard of, but that I personally think is worth pondering is National Invasive Species Week (Feb. 21-27).
I think everybody has an idea of what an invasive species is. Kudzu is probably our best local example, and you don’t have to drive very far to find a large patch of it seeking world domination. The ladybugs, stink bugs, and house mice that are getting in your home? You commonly see these undesirables described as “exotic invasive species.” Exotic normally meaning from another continent, and we have thousands of those. Some have naturalized and grow alongside our native species without doing too much harm. A lot of our wildflowers are in fact aliens. The “invasive” ones are the real troublemakers, and can rapidly grow to populations that negatively impact natural resources such as lakes, forests and farmland.
Invasive species usually have these common traits: They are fast growing, reproduce rapidly, have a strong ability to disperse and can tolerate a wide range of environmental conditions. With these abilities they are able to strong-arm native species, and either eat them, make them sick or take over their native habitats and growing sites. Because plant and animal based ecosystems are so interconnected, disrupting one native species through invasion often impacts many others.
The reason invasive species can increase so rapidly is that they no longer have natural controls in place that kept them in check in their native land, things like predators, harsher weather, browsing animals, etc. So when they get over here through either through accident or introduction, their survival rate is very high and they grow and spread like crazy.
As a forester and quasi-farmer I see a lot of local invasive species throughout our area. Emerald ash borer is hammering our native ash trees right now. Hemlock wooly adelgid is killing off our native hemlock groves that are so important to mountain stream habitats. Kudzu can take a forest with a hundred different plants and animals living in it and reduce it down to one species, itself. Invasive plants are to me our biggest threat, and I have a long list of plants I love to hate: kudzu, privet, autumn olive, bush honeysuckle, multi-flora rose, and tree of heaven to name just a few. Most of these can spread rapidly by producing berries that birds will eat and poop out for miles around. Over time I’m afraid they will give me fewer plants and animals to write about.
If you own much land, even just a grown up fence row, there’s a decent chance you have aliens lurking about, so beware, and fight back. Learn how to recognize our more common invasive species and how to deal with them from your local state forestry agency, agricultural extension service or Natural Resources Conservation Service.
Steve Roark is the area forester in Tazewell, Tennessee, for the Tennessee Department of Agriculture, Forestry Division.