Burning-wood ecology

Brush cleared from the area near the intersection of West Wilson and B roads burns in a recent brush fire. The large round object near the center of the pile is a bale of switchgrass from the bioenergy plots southwest of the Village. The waste bale was used to ignite the fire as an environmentally preferable alternative to a chemical fire starter. Photo: Dave Shemanske, FESS

Part of the job of caring for the Fermilab site is occasionally removing unwanted vegetation. An integral part of the task of restoring large land areas to a productive and diverse state is removing unwanted woody vegetation, such as European buckthorn and dead and potentially unsafe trees, like the hundreds of trees killed by the emerald ash borer over the last 10 years. Dead trees in unpopulated areas of the site are normally left to provide habitats for birds, mammals, insects and other invertebrates.

Restoration of woodlands choked by weedy, non-native species often requires lots of clearing before restoration can be effected. Parts of the Director’s Woods, the groves near Wilson and B roads and B and Receiving roads, and the Main Ring Savanna have undergone extensive clearing, which opens up the understory for the introduction of more desirable native plants. Some of the resulting biomass can be turned into mulch, but much of the scrubby material is disposed of by burning. Open burning raises questions about the ecological and environmental aspects of the practice.

Chief among the environmental concerns is the release of pollutants, specifically particulate matter that can act as a respiratory irritant. Thus burning brush as a part of our overall restoration effort requires a permit from the Illinois EPA, just like the more familiar prescribed prairie burns. The permit has conditions for burning that are intended to minimize the health impacts.

People are often concerned about the release of extra carbon in the form of CO2. It’s true that burning wood, like burning anything organic, releases CO2. However, on a geologic scale, the carbon released from even the oldest trees was only temporarily stored in the plant tissue and will likely cycle back and forth from plant and animal tissue to the atmosphere many times over a number of years.

Open burning of brush piles, such as prescribed burns of prairie or woodlands, has many benefits to the laboratory and to ecology. Like most every stewardship practice, it has some disadvantages as well, pointing (once again!) to the need to consider carefully all aspects of the actions we decide to take when managing our environment.

Rod Walton