The timing of a prescribed burn is important for its success. One timing factor is whether the season’s growth of invasive species is sufficient so that a burn will damage or kill these plants. Invasive plants are part of the “fuel load” of a prescribed burn. Most of fuel load is thatch, which is dead plant material that blocks the sun from germinating seeds, further promoting the growth of taller and faster growing invasive plants. Once thatch is burned off, deep roots of native prairie plants untouched by the fire have access to the sun and nutrients released by the fire.

Other important timing factors in deciding when to burn a prairie are air temperature, soil moisture, relative air humidity, and wind speed. There may be only a short window of opportunity when all of these factors combine to create the best conditions for a prescribed burn. Volunteers helping with a prescribed burn must be ready to move when conditions align for a good burn.

What Happens During a Prescribed Burn?

Preparation for a prairie burn begins in creating firebreaks to create smaller, more manageable areas for burning the prairie. We created firebreaks in our prairie’s design. The FUMC Prairie Trail System doubles as a system of fire breaks during prescribed burns. We have divided our prairie into sections that we burn in different years on a rotating schedule. Burning part, instead of the entire prairie also gives animal and birds an opportunity to move away from the fire during a prescribed burn.

Minnesota DNR and city permits are required to conduct a prescribed burn. FUMC contracts with Prairiescapes to coordinate and run our prescribed burns. Once DNR and Sartell burn permits are obtained and wind and weather conditions are right, Prairiescapes manager Steve Heymans, his crew, and FUMC volunteers gather to conduct a prescribed burn using water, proper fire control equipment, and a drip torch to start small, controlled fires. Before any fire is started, fire breaks are wet down. The drip torch is used to create a system of backfires that will do maximum damage to invasive plants, woody seedlings, and thatch, without burning out of control. Everyone monitors the fire and firebreaks. Under controlled conditions and careful monitoring, the fire will burn hot enough to kill invasive and woody plants, stay within the fire breaks, and burn itself out.

Do Prairie Burns Contribute CO2 to Global Warming? Scientists have studied how much carbon is released during a prairie burn and compared this to the amount of carbon absorbed by a prairie. Unlike burning fossil fuels, burning a prairie releases carbon that was recently absorbed from the atmosphere. In contrast, carbon released from burning fossil fuels is carbon absorbed by plants hundreds of millions of years ago. Research demonstrates that prairies pull more carbon from the air during a year than is released during a prairie burn. Prescribed burns are conducted on a 3-5 year schedule, so prairies managed by prescribed burns are releasing carbon once every 3-5 years. The capacity of prairies to sequester carbon, remove carbon from the atmosphere and store it in the soil, make prairie restoration an important strategy for responding to climate change. The deep root system of a mature prairie that stores atmospheric carbon rivals the carbon storage capacity of forests. In 2008, the state legislature mandated a study of the potential for carbon sequestration in Minnesota in forests and prairies on state and federal lands. The study concluded that carbon sequestration from state and federal land alone, is insufficient to offset Minnesota’s CO2 emissions. Prairie restoration on private land, like FUMC, has an important role to play in reducing CO2 in our atmosphere.

The burn management plan of the FUMC prairie is designed to maximize the growth and diversity of prairie plants. Above the ground, our managed prairie offers food and cover to pollinators, birds, and animals. Below the ground, the plants’ root system sequesters carbon produced by human activity that contributes to climate change. Prescribed burns play a critical role in maintaining the sustainability of our prairie system.