Invaders among us

Forty-five or so years ago when I roamed the young forests of Alamance County, North Carolina near my home, I never saw Japanese honeysuckle strangling trees. Floodplains and creek banks were covered in moss and wildflowers. Japanese stiltgrass and privet shrubs were nowhere to be found in such places.

The piedmont hills I explored had probably been agricultural fields thirty or forty years earlier. After they were abandoned, healthy piedmont forest began returning as it always had — as it still tries to do today when cleared land is left empty.

But thanks to intentional and accidental human assistance and the efficiency of modern transportation systems, alien species — plants, animals, fungi, and viruses — are moving into areas far from where they evolved. Beyond the reach of the checks and balances of their natal ecosystems, many of these non-native species are rapidly disrupting the native ecosystems they invade. The problem is world-wide and growing exponentially, and it is an issue I believe every piedmont gardener should be aware of.

When I speak to garden clubs about this issue, I am always asked why it’s a problem So what if new species move in — hasn’t that always happened? Isn’t that evolution in action?  No, this is not the same for many reasons.

For one, the time scales aren’t the same. Evolution is usually a very slow process, which provides all the components of an ecosystem with time to adapt to changes.  But modern transportation and human actions have accelerated the time scale at rates never before encountered by species attempting to adapt to changes in their environment.

And for those of us who love native forests, grasslands, and all our other native ecosystems, invasive non-native species are actively transforming some native environments into biological deserts, where the invading species dominate at the expense of most of the previous inhabitants. We are losing the rich diversity of our native fields and forests that support our wildlife — and us.

At the forefront of this battle to repel alien invaders are the people who manage and protect our national and state parks and other lands designated as worth preserving for their historic importance and/or extraordinary beauty and, often, rare species. Every time gardeners add  known alien invasive plants to their landscapes, they are increasing the likelihood that these plants will escape into adjacent natural areas, and eventually, to our special places — our parks and preserves — national treasuries of our nation’s biological assets.

What can piedmont gardeners do? You can identify and eradicate known invasive species from your landscape. And when you go to nurseries and garden centers to buy new plants, always ask if the plant is known to be invasive. If the store clerks don’t know the answer, don’t buy the plant until you’ve researched its invasive potential yourself. And if it is potentially invasive, don’t buy it.

Many non-invasive options exist for your garden. Many on-line resources are available to help you learn more about this subject.  And I guarantee you that, wherever you live, nearby conservation organizations are actively dealing with this issue and could use your help. Here are a few links to get you started.


  1. Getting Serious about Space Invaders in North Carolina: April 4-11, 2010 « Piedmont Gardener

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