At Soderville Park in Ham Lake, Minnesota, staff from the Anoka Conservation District (ACD) recently tested a new method for disposing of invasive buckthorn. Instead of creating smoky burn piles, they used a biochar kiln called the Ring of Fire.

The Ring of Fire is a type of biochar kiln designed to burn organic material (biomass)—such as wood and plant debris—in a low-oxygen, high-temperature environment. Compared to traditional burn piles, this process is more efficient and significantly reduces smoke, emissions, and environmental impact.

Traditional burn piles turn biomass into ash, which can generate large amounts of smoke, damage soils, and increase erosion. They also leave burn scars on the landscape that can persist for years, creating disturbed areas where invasive species may spread more easily.

How the Ring of Fire Works

The Ring of Fire works differently. The kiln is packed tightly with sticks and branches and then lit from the top. The flame at the top consumes oxygen from above, while the biomass inside the kiln is superheated with radiant heat. Instead of burning completely to ash, the material below undergoes a process called pyrolysis, in which the heated biomass is transformed into biochar—a stable, carbon-rich material similar to charcoal. 

When biochar is incorporated into the soil, that carbon can remain stored for hundreds to thousands of years, effectively locking atmospheric carbon into the ground rather than releasing it back into the atmosphere.

Biochar also provides ecological benefits for the soil. Its porous structure can bind excess nutrients such as nitrates and phosphates, reducing their availability and often favoring invasive plants. By capturing these nutrients, biochar can help slow the spread of invasive species that thrive in nutrient-rich environments.

Restoration Benefits at Soderville Park

At Soderville Park, the Ring of Fire also improved safety during the burning process. Since the fire's heat is at the top of the kiln, using the kiln prevents flames from heating the underlying peat soils, which can smolder underground if ignited.

After the burn, the biochar was spread in areas with high weed pressure. By absorbing excess nutrients in these soils, the biochar may give native plants—many of which are adapted to lower-nutrient conditions—a competitive advantage over invasive species.

By turning buckthorn piles into biochar, the Ring of Fire offers a creative way to support restoration goals while reducing smoke, protecting soils, and storing carbon.

- Article and photos by Lauren Schmeltzer

Activities to enhance habitat within 45 acres at Coon Rapids Dam Regional Park began this winter. The dense buckthorn that dominated the understory of the woodlands, wetland depressions, edges of Turtle Pond and the Mississippi River shoreline was cut and mowed. The Siberian elms invading prairie and turf areas were cut and removed, and several box elder trees were cut to create a canopy gap for greater diversity. Enhancement activities, including follow-up buckthorn and garlic control, a prescribed burn, native seeding, and turf-to-prairie conversion, will continue through 2030 with support from the Lessard-Sams Outdoor Heritage Funds.

For more information, contact Carrie Taylor, Restoration Ecologist, at This email address is being protected from spambots. You need JavaScript enabled to view it..

ACD wants to send out a huge thanks to the volunteers who spent a Saturday morning planting at Epiphany Ponds! ACD and the City of Coon Rapids are working together to reduce turf grass and expand native plantings at Epiphany Ponds Park. Volunteers planted native wildflowers and grasses to add to the seed mix. This is one of many plantings to create pollinator corridors in Anoka County.

For more information contact Carrie Taylor, Restoration Ecologist, at This email address is being protected from spambots. You need JavaScript enabled to view it..

The Sloneker family protected 58.5 acres of their land around Cedar Creek through the BWSR's Reinvest in Minnesota (RIM) program. Under the RIM program, the land remains privately owned but is protected by a conservation easement. Land protection along creeks and rivers improves water quality, reduces flood risk, and creates essential wildlife habitat corridors. For more information contact Carrie Taylor, Restoration Ecologist, at This email address is being protected from spambots. You need JavaScript enabled to view it.. 

Each year, the Anoka County Parks Department uses prescribed burns to manage ~200 acres of prairie and savanna habitats. Fire is a natural part of these ecosystems; it removes accumulated plant material, releases beneficial nutrients, fights the encroachment of woody plants, and helps control invasive species. Through these processes, fire boosts the native plant community and increases diversity. Prescribed burns are often paired with other management techniques such as mowing, applying selective herbicides, and supplemental seeding. 

Powerline corridors like this need to remain clear of woody vegetation, providing an opportunity for active prairie management in its place. This restoration also involved treating smooth brome (an aggressive invasive grass) before burning. Visit the U.S. Forest Service webpage to learn more about prescribed burns or contact Carrie Taylor, Restoration Ecologist, at This email address is being protected from spambots. You need JavaScript enabled to view it..