Saving Wisconsin’s Rarest Plant Community with Prescribed Fires
Columns of smoke. Flames licking at the base of oak trees, devouring lanky bushes and tall grasses. In most cases we find these images alarming. Face it, in the twenty-first century, we’re just not used to seeing fires on the horizon. And yet fire plays a critical role in the health of our Wisconsin ecosystems — it returns nutrients to the soil, clears dense and invasive brush, creates new habitats for native animals and is a key step in reproduction for some plant species. Today, fire is essentially “missing” and that has environmental repercussions on our Wisconsin ecosystems.
Prescribed burns are being used by Wisconsin Healthy Grown® potato growers to help restore one of Wisconsin’s rarest plant communities — oak savannas. Wisconsin’s oak savannas once covered 5 million acres — today, they occupy less than 1,000. Most of the fertile savannas’ acreage was converted to farms and homesteads, but fire suppression has also played a role in their decimation. Prior to European settlement, fires occurred once every three to five years thanks to natural occurrences, lightning or Native Americans. When those fires were suppressed the ecosystem changed. Weedy trees, brush and dead vegetation usually consumed by fire — and thus releasing nutrients into the soil — continued to grow and grow and grow, overtaking the landscape and crowding out oaks, whose thick bark makes them fire resistant. Openings in the canopy disappeared, strangling the growth of oak seedlings. And understory grasses and flowers that prefer the dappled shade began to disappear under the overcrowded, darker canopy. Eventually, non-native plants introduced into the ecosystem by settlers began to take over. And the soils generally became depleted.
With less than 0.01% of quality oak savanna in existence today, Healthy Grown growers work closely with the University of Wisconsin on prescribed burning of non-farmed lands. Prescribed burns can also be used to restore endangered Wisconsin grassland, pine savanna, woodland and wetland ecosystems in central and southern Wisconsin. Each of these ecosystems will benefit from restoration measures
Why prescribed burning?
- Historically, many of the ecosystems in southern Wisconsin were adapted to regular fire intervals, and so have a competitive advantage over exotic species (which are typically not fire-adapted) when fire is reintroduced. The end result? Non-native invasive species are reduced or eliminated, allowing native species to return.
- Grassland birds, and many other grassland animals in Wisconsin, depend on open landscapes for their habitat requirements. Fire helps maintain the open horizons they need.
- Fire helps keep grassland ecosystems open and free of shrubs.
- In prairie ecosystems, prescribed fire warms the soil in the spring, stimulating the growth of fire-adapted prairie plants while also controlling the growth of exotic, non-native grasses.
- A number of native Wisconsin plants depend on fire for seed germination. For example, jack pine, common in the Central Sands, depend on the high heat from fire to stimulate opening of the pine cone, and release of the seeds.