Large tracts of prairie and oak savanna once covered parts of Anoka and Isanti Counties. Fires started by lightning would sweep through these habitats and the native flora and fauna became adapted to periodic burning. Since towns and homes have been established in nearby areas, it has become too dangerous to allow such natural fires to burn freely. Cedar Creek manages the prairies and now-rare oak savannas by setting controlled fires called prescribed burns.
Cedar Creek has been practicing prescribed burning since the 1960s, making it one of the longest ongoing scientific fire experiments in the world. Researchers at Cedar Creek study the effects of fire at individual, community, and ecosystem levels with the goal of maintaining the prairies and developing effective restoration methods for the savanna.
Occasional fires are healthy for almost every ecosystem, from savannas and prairies to rainforests. Fire rejuvenates as it burns, dumping nutrients back into the soil and creating a rich fertilizer. Sunlight warms the blackened earth and encourages seed germination. In prairies, native grass roots extend deep into the soil. After a fire clears out encroaching woody shrubs, which shade out native species, grasses quickly regrow. Plants damaged by animal foragers are burned down and given a fresh chance to grow.
Animal life benefits from the vegetation changes caused by fire as well. Deer, squirrels, and wild turkeys consume increased acorn production. Some birds, like bluebirds, bobolinks, Sandhill Cranes and sharp-tailed grouse require open areas and do better when brush is burned away. Other birds like mourning doves, pheasants, upland plovers and many sparrows nest in native prairie grasses. Red-headed woodpeckers and pileated woodpeckers use standing dead trees for foraging and nesting; indigo buntings use dead snags and branches for conspicuous singing perches.
Casualties are minimal. During a fire, birds and large mammals temporarily leave the area; amphibians, reptiles, and small mammals survive by burrowing under the soil surface. Although many invertebrates such as spiders and insects will be killed, these species quickly recolonize a burned area. Any negative short-term effects from the fire are overwhelmed with the positive long-term effects. Birds may lose a nest, but Cedar Creek’s prescribed burning season is finished before the breeding season is, and many birds will construct another nest. The following year, vegetation regrowth creates more and better nest-building sites for native bird species.
Generally, periodic controlled burns reduce the risk of a large, catastrophic fire by getting rid of standing fuel such as dead tree limbs and brush. A mix of fire regimes will also lead to a greater diversity of species, as different species either thrive or do poorly under different fire regimes.
Prescribed burning at Cedar Creek is supervised by trained personnel with many years of collective experience. Local fire departments, state natural resource offices, and law enforcement agencies are on stand-by during burns. All burns are conducted within a prescription: a set of guidelines for weather and safety, taking into account factors such as humidity, temperature, wind speed, and wind direction. Prescriptions are written with the help of the Minnesota Department of Natural Resources and are designed to be as safe as possible. All areas to be burned are surrounded by roads, water, or tilled firebreaks and monitored by personnel until the fire has burnt out or is extinguished.