River Bum Log: Burning on the bluffs under blue skies

From the ashes, native prairie grass and its endangered inhabitants will regrow on lands along the St. Croix.




4 minute read

It was about 32 degrees when the first flames were lit on Wednesday morning at Buffalo Skull. I huddled close to the burning grasses to fend off the chill. The river was just over the bluffs, the water getting colder and colder.

The parcel of prairie and oak savanna south of Osceola is part of the Standing Cedars Community Land Conservancy. It’s owned by the nearby Philadelphia Farm, but Standing Cedars has easements to manage the land.

In this case, management means keeping the unique habitats mostly free of trees and shrubs. The prairies are under constant threat of invasion from sumac and red cedars, while the sparsely-studded oak savanna is besieged by non-native buckthorn.

Fire is one of the best ways to achieve those goals. And, because the farm that owns the site is organic, no herbicides can be used anyway.

The grasses love fire, and will quickly grow back next spring. The woody stuff simply can’t handle it, and burning the land gives the grass an advantage.

There was a crew of about eight people working the fire. My friend Ryan torched the downwind side to create a wide swath of blackened ground, with two of us standing by to watch and control its spread. A fellow named Alex then lit the upwind side and let the breeze blow the flames through the prairie to meet our fire, where it would stop due to a lack of fuel.

Two of the volunteers were deer hunters that contribute volunteer hours every year for the privilege of bow-hunting the property. They had been out before dawn that morning, and then chipped in with the fire.

The hunters recalled that when they started hunting the property 15 years ago, the prairie was choked with trees and brush, more forest than grassland. A steady regime of cutting, mowing, and burning had restored it to it valuable prairie habitat.

But despite bark scraped off trees bordering the prairie, a clear sign of bucks, the hunters hadn’t seen many deer.

The grass burned better than expected. Much of it was still cold and damp from the night’s frost, and the morning’s cloudy skies didn’t help dry it out. But shortly the clouds cleared, the sun came out, and the flames spread. We burned two big sections, the fire taking mere minutes to cross the prairie. The flames seemed to heat and dry the grass ahead of them, and stands of little bluestem crackled loudly as they were consumed.

After the fire passed over, the underlying soil and bedrock outcrops was easily visible. It was also easy to see why farmers had quickly given up on this piece of land: the soil was shallow over hard basalt. It probably broke a couple plows before they gave up and used it for grazing and hay for a while. That light use is also probably why the native plants quickly returned when it was retired from agriculture.

I lugged five gallons of water on a tank in my back, and sprayed it along the edge of the fire, helping create a “cold edge.” Working near the bluff on the second section, the smoke frequently blew over me, and I sought gulps of fresh air in the woods overlooking the river.

One section was left unburned because it was where the eggs of endangered Karner blue butterflies were transplanted this spring as part of an $800,000 project in the area led by the U.S. Fish and Wildlife Service. The butterfly larvae require the lupine wildflower to survive, and this patch of Standing Cedars offers a lot of the purple plant.

After we burned the second section, Ryan and I were walking back to meet the group when he stopped and pointed at some small green leaves among the black. It was a large population of endangered kittentails (Besseya bullii), a unique wildflower that seems to love the St. Croix Valley, and survives in strongholds along the river.

The fire didn’t burn so well in the third spot, a rise to the east of the prairie. This was the oak savanna, which had been cleared of thick buckthorn thanks to hundreds of volunteer hours. I had helped stack some of the brush into burn piles a year or two ago.

But of course the buckthorn is growing back, with leafy green shoots already a foot or two high in many places. While the plant can’t tolerate fire, it can be hard to burn, as its leaves were still green while dry oak leaves burned on the ground.

Ryan told me Standing Cedars is considering employing goats in this area to suppress the buckthorn regrowth. Sites separated by a hundred yards can demand drastically different management techniques.

There was a lot of black ground when I left. Next spring it will quickly blossom with grasses and flowers, and perhaps a few rare butterflies. Fire is just as much a part of the prairie ecosystem as those plants and animals.

If you want to visit Buffalo Skull to see our work, or go in the spring to see the kittentails and Karner blues, visit this site for access information. Plug this address into your map to find it: 2849 55th Ave., Osceola, Wis. While the parcel is open to the public, the township road that provides access is pretty rough.


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If you have any questions, please email greg@stcroix360.com


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River Bum Log: Burning on the bluffs under blue skies