Spring in the Oak Savanna – Tone Madison

A crew member sets a controlled fire on the oak savannah at the UW-Madison Arboretum.  Dense orange flames are visible in the foreground;  in the background the worker carries a drip torch and wears fire protection equipment.  Photos by Sam Harrington.
A crew member sets a controlled fire on the oak savannah at the UW-Madison Arboretum. Dense orange flames are visible in the foreground; in the background the worker carries a drip torch and wears fire protection equipment. Photos by Sam Harrington.

Climate change makes it more difficult to maintain these ecosystems through controlled burning.

Psssst: I’m so glad you’re here. If you haven’t read the winter edition of this series again, you should check it out before this one. It has important context that you don’t want to miss :).

This is the second in a four-part series by Sam Harrington chronicling a year in the life of Dane County’s oak savannah restoration projects through the seasons.

The perfect day for a prescribed burn is sunny with light, steady wind. April 25, 2022 was none of that. And yet, a crew was burning the Oak Savanna — a prairie ecosystem with scattered oak trees — just west of the UW-Madison Arboretum’s main parking lot.

Sponsor

They would have preferred to burn on a day with blue skies, because on cloudy days the smoke hangs close to the ground. But as damp and dark as it was in Dane County this spring, the team didn’t really have a choice.

“I’m afraid we don’t have many days left,” said Michael Hansen, groundskeeper at the Arboretum.

Smoke hangs near the ground in the oak savannah due to cloudy weather.
Smoke hangs near the ground in the oak savannah due to cloudy weather.

So they used drip torches to light small fires in the dry grass that remained under the oak trees from the last growing season, and they did.

Prescribed or controlled burns are intentional fires aimed at managing the health of ecosystems. They remove dead brush and plant matter, and make it more difficult for non-native species to settle. In savannahs, fire also helps keep unwanted tree species away and prevent the canopy from becoming too shady.

This allows grasses and wildflowers to form the carpet of the savanna and creates habitats for grassland bird species like bluebirds and red-headed woodpeckers.

Fires like the one in the arboretum echo the centuries-old traditions of local tribes like the Ho-Chunk. Indigenous peoples in the oak savanna-dominated landscapes of southern Wisconsin managed wildfires and used controlled burns to keep grasslands from becoming too overgrown.

The typical prescribed fire season in southern Wisconsin is from mid-March to mid-May, which follows our wildfire season schedule. Fires are less likely to spread if there is snow on the ground or if plants are too green. During the intervening months, there is plenty of dead plant material on the ground for the fires to use as fuel.

Similar to 20th century forest policies, there was a long period in the United States where fire suppression in grassland ecosystems was the norm. This has led to degraded oak savannah communities.

“With the suppression of fires in the landscape and the arrival of invasive species, they’ve really grown into a sort of thicket of brush and trees,” said Lars Higdon, botanist/naturalist for Dane County Parks.

So land managers and conservation groups are increasingly bringing fire back into the savannahs. In the midst of this change, spring becomes an increasingly complicated time to burn.

A crew member watches a fire he started moments earlier to make sure it's going where it's wanted.  The crew member is shown in the foreground in fire protection gear and holding a drip torch, gazing at a band of flame.  A second worker, similarly equipped, is in the background amid hazy smoke and dense, dry vegetation.
A crew member watches a fire he started moments earlier to make sure it’s going where it’s wanted.

There has always been an ironic overlap between the late winter/early spring flood season and the spring fire season, but climate change is making spring even wetter in Wisconsin.

Steve Vavrus, co-director and senior scientist of the Wisconsin Initiative on Climate Change Impacts, puts this change in historical perspective.

Even with the freak drought of 2021, “spring precipitation for the past 25 years has been higher than any 25-year period in the entire record, dating back to around 1870 in Madison,” Vavrus said. “It’s striking how wet it is.”

This trend is expected to continue into the future, and spring is expected to experience the greatest increase in precipitation of any time of year in our region.

Rainstorms are also becoming more extreme around the world due to climate change, as the warmer atmosphere retains more moisture, according to the International Panel on Climate Change. Vavrus said while many of these heavy rains traditionally occur in the hot summer, they are expected to occur more often in the spring and fall as those seasons warm.

During heavy rains, native landscapes like oak savannas and grasslands are important allies to their human neighbors. The deep roots of grasses and wildflowers absorb rainwater and reduce erosion. This can help alleviate flooding.

But wetter springs can complicate burning regimes, which in turn threatens ecosystem health. Oak savannahs generally need to be burned annually when a restoration project is in its start-up phase and once every three to five years after establishment. This year, crews like Hansen’s, who have many acres to burn, find themselves setting fires on days when weather conditions are less than ideal just to do so.

In order to adapt to wetter springs, burning seasons may have to change, or crews may have to make more fires in fewer days.

Hansen said the Arboretum, and others, are experimenting with prescribed burning earlier in the season and even extending it into the growing season. “Sometimes people burn a south-facing slope when the snow has melted on the slope but the surrounding area is still snow-covered,” Hansen wrote in an email. “We did it in February this winter at one of our sites.”

A fire crew member uses a drip torch to ignite small fires in dry grass and brush.  Small patches of flames are visible on the ground amid dry, brown vegetation.
A fire crew member uses a drip torch to ignite small fires in dry grass and brush.

To do more fires in fewer days, more people will need to be trained to execute and manage prescribed burns. Operation Fresh Start (OFS), a Madison-based organization that helps emerging adults through education, mentorship, and job training, recently launched a conservation academy. The academy, which pays at least $15 an hour, helps participants gain certification in fire management as well as other land management skills like applying pesticides and using a chainsaw .

The conservation academy was born out of a need to help participants find jobs in conservation. They often compete with holders of college degrees in biology and environmental sciences.

Cory Rich is responsible for construction and conservation at OFS. “The conservation field, probably no secret, is largely dominated by white males,” Rich said. “So [we’re] looking to try to diversify that and create those inroads for people who have been traditionally excluded.

The Operation Fresh Start legacy program, which helps 16- to 24-year-olds get their high school diploma, driver’s license and work experience, also has a conservation team. In all, approximately 40 to 50 young people are working on conservation projects in Dane County at any one time through OFS.

“People don’t always have a lot of respect for the work ethic of young people,” Rich said. “But, man, these young people, these are people who haven’t had the traditional success that most people often think, but they’re out in minus 20 degrees in the winter, and they’re out in the 100s in been working to beautify the earth.

The program also helps participants build a lasting relationship with the land and ecosystems of southern Wisconsin. As we all head into a future riddled with the impacts of climate change, conservation work becomes even more critical.

“People often think that forests are our lungs for the planet, and they sequester carbon, and they certainly do all kinds of wonderful things for us,” Higdon said. “But oak grasslands and savannahs are also very good at sequestering carbon, mitigating flooding and providing habitat for pollinators. There are all kinds of ecological services that are provided by these communities.

The fire crew starts burning so that the fire moves in the wind.  Prescribed burns are often done upwind to keep them smaller and easier to control.  A crew member is seen through a gap in the trees in the foreground, carrying a torch and wearing fire protection gear.  Small patches of flames are visible on the ground in front of the crew member.
The fire crew starts burning so the fire moves in the wind. Prescribed burns are often done upwind to keep them smaller and easier to control.