The whir of brush saws echoes daily through Kelleher Park in Burnsville as workers cut down the invader: buckthorn. Cropping up in thickets of prickly shrubs and small trees, this pest has been slowly choking off the undergrowth of plants and wildlife in this rare bur oak savannah. So with the help of a state grant and volunteers, an unusual forest restoration project is under way to chop down and chip up the buckthorn and haul it to St. Paul, where a biomass plant will burn it to produce electricity.
It's one of 10 woody biomass experiments around the state funded with a half million dollars in grants from the Department of Natural Resources. Using a $78,000 grant, Burnsville's project is to be completed by Feb. 15, said Angela Hanson, the city's natural resources technician.
"We can't eradicate it," Hanson said of the buckthorn shrubs and trees, which can grow to 25 feet tall, while crowding out life in the understory. "We're just trying to stem the tide."
The 147-acre Kelleher Park just south of County Road 42 is home to a rare 26-mile expanse of bur oak savannah, one of the most critically endangered ecosystems in the world, Hanson said. Once common in parts of east-central and southern Minnesota, more than 99 percent of such savannahs have either disappeared or been converted to shady thickets dominated by buckthorn and other invasive plants, she said.
"That's partly why this project is so important -- it is an opportunity to restore unique and rare habitat types," agreed Barb Spears, the DNR woody biomass project coordinator.
The projects on public and private lands will help restore more than 7,000 acres of overgrown prairie, oak savannah and woodlands by removing undesirable growth, from buckthorn to prickly ash. Each project is within 75 miles of District Energy of St. Paul, the biomass plant that's the biggest hot water district-heating system in North America and a leader in renewable energy.
A major buckthorn removal operation was completed in December in Indian Mounds Park in St. Paul using some of the grant money approved by the Legislature in 2007. District Energy and an affiliate agreed to truck out the material that is chopped down at Kelleher in exchange for the right to burn it.
Jeff Guillemette, biomass fuel procurement supervisor for Environmental Wood Supply, which is getting the buckthorn to St. Paul, said it burns well for energy. He estimates that the firm will reap 20 trailers, each containing 100 cubic yards of the material, from Kelleher Park.