The Nature Conservancy. Protecting nature. Preserving life.™

kudzu © Barry Rice

Over and over, we have learned that the most cost-effective way to manage invasive species is to prevent their arrival in the first place. An ounce of prevention is worth a pound of cure!

When invasions do occur, detecting the invasive species when its populations are still small can dramatically change the course of the invasion. In such cases, eradicating the invasive can be easy, and then we can turn our attention to preventing further invasions.

All too frequently, detection of an invasion is not early enough, and we must deal with large infestations of invasive organisms. At such times, our efforts to control the invasions need to be as effective as possible. We determine the appropriate method based on best practices we have established and follow stringent guidelines to reduce any potential side effects of our efforts. Minimizing risk to the native species and ecosystems we are trying to protect is always a priority when selecting a control method.

Controlling Invasions

For invasive plants, we may pull or girdle them to cut off their water supply. We may use prescribed fire, biocontrols (e.g., natural predators), judicious applications of herbicides, flooding, or other methods. By cutting back plants and applying small amounts of herbicides, we successfully contained invasive phragmites in the unique wetlands of Massachusetts.

For invasive animals, relocation is rarely effective and sterilization has never been demonstrated to be effective against the species we have worked on or in remote, hazardous mountain terrain. Unfortunately, this means that such animals often have to be trapped or hunted. This is a sad result of foreign animals being introduced to, and in some cases escaping into, delicate habitats — another reason that preventing introductions of alien species is so important.

Adaptive Management

To ensure our efforts are effective, we use a scientific method called “adaptive management.” This approach involves setting realistic targets for control, identifying the best response and evaluating how effective our efforts have been once the plan has been implemented. The use of such rigorous scientific methods reduced invasive Japanese knotweed populations by 80% over two years along the banks of the Sandy River in Oregon.