Many management strategies can be used against invasive plants. In most cases, no single strategy used by itself will provide the desired long-term solution that landowners and managers seek. However, when used together as part of a larger integrated strategy, they can provide significant benefits for achieving successful, long-term management. A prescribed burn is used as an invasive plant control tool, and to manage native plant communities and large landscapes.
At the Minnesota Department of Transportation (MnDOT), one goal of prescribed burns is to improve the health of desirable vegetation. Ken Graeve with MnDOT says they use prescribed burns to promote the growth of desirable vegetation in combination with other treatments such as herbicide applications. With these combined methods, a healthy ecosystem is better able to outcompete invasive plants.
The Minnesota Department of Natural Resources (DNR) uses prescribed burns not just for managing native plant communities, but also for controlling woody invasive plants. For example, after initial work of cutting and treating with herbicide application, the DNR may use prescribed burns in subsequent months and years to help control infestations of buckthorn, honeysuckle, or Japanese barberry. Shawn Fritcher from the DNR says prescribed burns can be effective against these invasive woody plants because burns can cover large areas faster than cutting and treating can. Multiple burns are often needed to reduce the vigor of woody invasive species. Fritcher also says it is important to note that repeated fire is most appropriate in fire-dependent woodlands.
At both MnDOT and the DNR, staff who work on prescribed burns go through training. They learn about fire behavior, weather prescriptions, and how to design and write an effective burn plan. Fire breaks, or the breaks in combustible material, are often established ahead of time using a variety of equipment like tractors, mowers, ATVs, rakes, and leaf blowers. Fire breaks are controlled using trucks or ATVs that carry water, or with hand tools where access by ATV is limited. The appropriate permits must be acquired, and traffic control measures are utilized for burns along roadsides.
Timing prescribed burns depends on the management objective. Desirable plant species often respond well to early spring burns. Smooth brome and other cool season grasses can be managed with late spring burns. Burning woody invasive species after leaf-out may be the most effective since much of the plant’s energy is invested in new above ground growth. Summer burns can be effective at controlling brushy species in prairie areas. Fall burns provide another opportunity to target some invasive species.
For landowners thinking about utilizing prescribed burns, they must first get a burn permit. Proper planning for the burn is critical to success. The landowner needs to think about many factors such as fire break location, wind direction, smoke, control measures, and many other parameters to make decisions for the burn plan. There are multiple resources through the DNR website to assist landowners with planning prescribed burns.