Native vs Invasive
So what do we mean by “invasive species?” Here’s the answer.
There is much confusion surrounding the meanings of terms like “native” and “invasive.” What are “native” species? What are “invasive” species? Are plants and animals that are not “native” automatically invasive? The answers are not always clear. The terms “native” and “invasive” really describe very different aspects of the biology of a plant or animal.
Native species are species that developed in or arrived in a particular environment through means other than transport by humans. They might or might not be invasive. Some examples of native species might include cherry bark oak and armadillos. There is no record of the first cherry bark oaks being brought to Arkansas. It has been here as far back as our records can trace. Everyone accepts that cherry bark oak is native to Arkansas. Armadillos, on the other hand, are recent additions to our fauna but invaded Arkansas though natural means. Some people argue that they are not a native species, while other people argue that they are a native species. We are unlikely to settle that debate here. Either way, though, armadillos are invasive.
“Invasive” species are plants and animals that are adept at exploiting new environments. They might or might not be native. Invasive species will quickly move into a new environment and vigorously compete with other plants or animals in that environment. Some examples of invasive species might include sweet gum and kudzu. Sweet gum is a native species that is also invasive. Let any field in Arkansas stand fallow for a few years, and sweet gum will grow in it prolifically. This is not a problem because sweet gum has natural competitors and some trees can out-compete sweet gum in the long term. These processes keep sweet gum populations in check over the long term so that pure stands of sweet gum rarely persist. Kudzu, like sweet gum, is an aggressive invader of disturbed habitats. However, kudzu is different from sweet gum because it was brought here by humans and it has few natural competitors in Arkansas. As a result, it tends for form pure stands that eliminate essentially all other plants. The resulting ecological communities lack the diversity that once existed on the site. They have been changed for the worse by a non-native invasive species.
When we examine concepts of native or non-native species and concepts of invasive and non-invasive species, we find that we can group plants and animals into one of four categories. They may be native and invasive, or native and non-invasive, or they may be non-native and invasive, or non-native and non-invasive. Three of those categories present little concern to us. Native species are part of our natural environment. There are feedback mechanisms in our environment that keep native invasive species in check in the long term. Non-native species that are also not invasive are not a problem for us because they do not persist in our environment. They are at a competitive disadvantage, so without human intervention, they will die out. The non-native invasive species, however, present a real problem to us. There are no feedback mechanisms in our environment to keep these plants and animals in check. As a result, they aggressively invade and degrade our native ecosystems, often resulting in long-term damage to wildlife habitat, soil, water quality, and sometimes even infrastructure.
Several states already have programs in place to track the spread of non-native invasive species. The University of Arkansas Division of Agriculture is developing such a program for Arkansas.
