Controlled burns have a rich tradition here in Minnesota, where grasslands and oak savanna have thrived under the practice.
It’s high noon in early May, and the gravel parking lot at the Louisville Swamp Unit of the Minnesota Valley National Wildlife Refuge between Chaska and Jordan is bustling with activity.
Instead of nature-seeking hikers, bird-watchers and photographers, 18 firefighters, most with the U.S. Fish and Wildlife Service (USFWS), are preparing their drip torches, chain saws, water hoses and other equipment for the work ahead. Several trucks and four-wheelers, some equipped with water tanks, are scattered in a semicircle. A mixture of gas and diesel fuel lingers in the air as a red-tailed hawk rides the thermals overhead. Most firefighters are either inhaling a quick lunch or enjoying some playful small talk. But their body language quickly turns serious when the “burn boss” begins the daily “burn briefing.” It’s time to work.
“OK, listen up,” says Ryan Petersen, a range technician with the U.S. Fish and Wildlife Service, as he scribbles (in erasable black marker) the day’s assignments on the so-called white board, which is actually one of the truck’s white-colored passenger doors. “Act decisively, keep your wits and pay attention to what’s going on out there.”
In minutes, the fire crew, many of whom are friends, races off in their trucks and four-wheelers to conduct a prescribed (or controlled) burn on 250 acres of the scenic 2,600-acre unit, an outdoor oasis in one of the state’s fastest-growing regions.
They’re not alone. Each spring, federal and state wildlife officials intentionally set fires on public lands to improve grassland and forest habitat for numerous wildlife species — an old-as-dirt land management technique that has its roots in Native American culture. These prescribed fires are meticulously planned for months and conducted by seasoned professionals.
“Fire is often misunderstood by the public, because what they see on television — like a wildfire in California — isn’t what we’re doing here,” says Lee Nelson, a retired fire management officer with the USFWS who occasionally assists his former co-workers on prescribed burns. “This is a controlled burn, and it’s conducted only under predetermined weather conditions — when it’s not too dry and not too windy, etc. We do have wildlife habitat management objectives, but safety is always our first and last consideration.”
LONG RECORD OF BURNS
Before European settlement, Nelson says, wildfires, typically ignited by lightning, reinvigorated the nation’s sprawling grasslands and brushlands. Fire also set back or killed troublesome woody plants, while deep-rooted prairie grasses went unharmed and flourished. The era’s predominant grazing animals, bison and elk, were direct beneficiaries of fire. “I call it the The Grocery Store Effect,” says Nelson. “Those old large grazers loved that new growth after a fire. To them, it was like eating ice cream.”
Native Americans intentionally set fires to stimulate plant growth on grasslands and to keep forest areas open to encourage blueberry production. Early European settlers used fires to keep pastures open and healthy.
“Truth is, fire is a big part of our natural history as a nation,” says Nelson, who began “working with fire and learning its behavior” with the U.S. Forest Service after he graduated from college in 1978.
FIRE AS FERTILIZER
On this day, the controlled burn is being conducted on Louisville Swamp’s “showcase” upland section, which sits just beyond the main parking lot in Shakopee. It’s a rare ecosystem called oak savanna that features scattered oaks above a lush layer of prairie grasses and wildflowers. More than 200 species of birds depend on this habitat throughout the year.
“Minnesota has about 1 percent of its tall-grass prairie remaining, and intact oak savanna is even rarer,” says Nelson, as he follows the burn crew on foot on one of the unit’s fire breaks, which doubles as a public hiking trail. “Historically, this ecosystem evolved under fire; it needs it every few years to beat back undesirable woody vegetation that could turn into a forest of red cedar, buckthorn and box elder. Fire also helps remove thatch that accumulates over time. Fire is the most cost effective and ecologically effective land management tool we have for this type of habitat. That’s why periodic prescribed burns are so important.”
As Nelson looks on, the burn crew uses drip torches to start the fire. The fire crackles and smoke quickly billows from the ground. The wind, which is moving in an easterly direction, pushes the fire along. In less than four hours, the entire 250 acres is burned. “You’ll be surprised how fast this charred earth begins to green-up,” says Nelson, noting the ecosystem’s oak trees are fire-tolerant and rarely lost. “It won’t take long.”
After a burn, Nelson says, nature works its magic. The blackened soil quickly absorbs sunlight. The warmed earth accelerates seed germination and the charred plant remains transform into a rich, natural fertilizer, setting the stage for new plant growth. “Once this prairie grows back, it will grow back thicker and healthier. Typically in the fall after a burn, we see a spike in seed production and insect populations, and both are beneficial to a host of critters out here.”
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