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A season of fire and flood: Spring in the oak savanna

Climate change is making it harder to maintain these ecosystems through controlled burns.
A crewmember sets a controlled fire on the oak savanna at the UW-Madison Arboretum. Dense orange flames are visible in the foreground; in the background the worker is shown carrying a drip torch and wearing fire-protection gear. Photos by Sam Harrington.
A crewmember sets a controlled fire on the oak savanna at the UW-Madison Arboretum. Dense orange flames are visible in the foreground; in the background the worker is shown carrying a drip torch and wearing fire-protection gear. Photos by Sam Harrington.

Climate change is making it harder to maintain these ecosystems through controlled burns.

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

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

The perfect day for a prescribed burn is sunny with light, consistent wind. April 25, 2022 was none of those things. And yet, a crew was burning the oak savanna—a grassland ecosystem with scattered oak trees—just west of the main parking lot at the UW-Madison Arboretum. 

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They’d have preferred to burn on a day with blue sky, because on cloudy days the smoke hangs close to the ground. But as wet and gloomy as it’s been in Dane County this spring, the team didn’t have much choice.

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

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

So they used drip torches to ignite small fires in the dry grasses that were left under the oaks from last growing season, and got it done.

Prescribed, or controlled, burns are intentional fires set to manage the health of ecosystems. They clear out brush and dead plant matter, as well as make it more difficult for non-native species to take hold. In savannas, fire also helps keep out unwanted tree species and keep the canopy from getting 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. People indigenous to the oak savanna-dominated landscapes of southern Wisconsin would manage wildfires and use controlled burns to keep the grasslands from becoming too overgrown.

The typical prescribed fire season in southern Wisconsin is mid-March to mid-May, which follows the calendar of our wildfire season. Fires are less likely to catch if there’s snow on the ground or if the plants are too green. During the months in between, there’s lots of dead plant matter on the ground for fires to use as fuel.

Similar to policies in forests throughout the 20th century, there was a long period in the U.S. when fire suppression in grassland ecosystems was the norm. This led to degraded oak savanna communities. 

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

So land managers and conservation groups are increasingly bringing fire back to savannas. In the midst of that shift, spring is becoming an ever-more complicated time to burn. 

A crew member watches a fire they lit moments earlier to make sure it goes where it is wanted. The crew member is shown in the foreground in fire-protection gear and holding a drip torch, looking at a strip of flame. A second worker, similarly equipped, is in the background amid hazy smoke and dense, dry vegetagion.
A crew member watches a fire they lit moments earlier to make sure it goes where it is wanted.

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

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

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Even with 2021’s anomalous drought, “spring precipitation over the last 25 years has been higher than in any 25 year period in the whole record, going back to about 1870 in Madison,” Vavrus said. “It’s striking just how wet it’s been.”

That trend is expected to continue into the future, and spring is expected to see the largest increase in precipitation of any time of year in our area.

According to the International Panel on Climate Change, rainstorms are also getting more extreme worldwide due to climate change, as the warmer atmosphere holds more moisture. Vavrus said that while many of these heavy rain events traditionally happen in the hot summer, they are expected to occur more often in spring and fall as those seasons warm up. 

During heavy rains, native landscapes like oak savannas and prairies are important allies to their human neighbors. The deep roots of grasses and wildflowers soak up stormwater and reduce erosion. This can help mitigate flooding.

But wetter springs can complicate burning regimens, which in turn threatens the health of the ecosystem. Oak savannas typically need to be burned every year when a restoration project is in its beginning phase and once every three to five years after they are established. This year, teams like Hansen’s, who have many acres that need to be burned, find themselves starting fires on days with less-than-ideal weather conditions just to get it done. 

In order to adapt to wetter springs, burning seasons may have to shift, or crews will need to conduct more fires on fewer days. 

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

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

To fit more fires into fewer days, more people will need to be trained to run and manage prescribed burns. Operation Fresh Start (OFS), an organization based in Madison that helps emerging adults through education, mentoring, and job training, recently started a conservation academy. The academy, which pays at least $15 per hour, helps participants become certified in fire management as well as other land-management skills like pesticide application and chainsaw operation.

The conservation academy was born out of the need to help participants get jobs in the conservation field. Often they are competing with people who have college degrees in biology and environmental sciences. 

Cory Rich is the construction and conservation manager 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 these inroads for people that have been traditionally excluded.”

The Operation Fresh Start legacy program, which helps 16- to 24-year-olds get their high school diploma, drivers license, and work experience, also has a conservation crew. In all, there are about 40 to 50 young people working on conservation projects across Dane County through OFS at any given time.

“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 folks that have not had traditional success in the way that most people often think of it, yet they’re out in minus 20 degrees in the winter, and they’re out in the 100 degrees in the summer working to beautify the land.”

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

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

The fire crew starts the burning so that the fire will move into the wind. Prescribed burns are often conducted against the wind to keep them smaller and easier to control. A crewmember is seen through a gap in the foreground trees, carrying a torch and wearing fire-protection gear. Small patches of flame are visible on the ground in front of the crewmember.
The fire crew starts the burning so that the fire will move into the wind. Prescribed burns are often conducted against the wind to keep them smaller and easier to control.

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