Environmental Experts Speak: Connie Mutel and Iowa’s oak woodland

Photo by Carl Kurtz

Cornelia “Connie” Mutel is a senior science writer and archivist in Iowa’s Institute of Hydraulic Research. She has completed eight books, many of which focus on Iowa’s ecology. Connie and her husband, UI professor Robert Mutel, live on 18 acres of oak-hickory woodland near Iowa City. Within the next week they will perform a controlled burn on part of the oak woodland.

Connie spoke with Iowa Environmental Focus and discussed the history of Iowa’s ecology and the importance of controlled burns:

 What are the oaks’ history in Iowa?

“If you look at the General Land Office surveys of Iowa’s original vegetation, you can see that in the mid-1800s, 75 to 80% of our trees were oaks. We had a fire-tempered landscape, and the vast majority of Iowa would burn regularly. The woodlands and wetlands would burn less often and less intensely than the prairies, but they were also fire landscapes.

“The story with oaks is that oaks can’t reproduce without sunlight, and the only way to get sunlight to the woodland floor is by reducing tree density. In past centuries, this meant that oak woodlands were dependent on the thinning action of fire for survival. Using this information, we can reconstruct the geography of trees in Iowa prior to Euro-American settlement, which started here in the 1830s.

“Oaks (and also some hickories) grew on the uplands. Down in the bottomlands, which burned less frequently (because they were wetter and more sheltered from wind), you had a diversity of trees with thinner bark. Those thin-barked trees [in the bottomlands] couldn’t survive the heat of fire, and so they were eliminated from uplands. In contrast, the oaks can survive fire because they have a thick corky bark.

“So, like the prairie (which covered the majority of Iowa), the oaks are fire tolerant and fire dependent. As you went up the hillside, oak density got thinner and thinner up to the tops of the hills. That’s where fires burned more frequently, because the landscape was driest and winds were strongest there; that’s where the most open oak savannas proliferated. So, the vast majority of Iowa’s wooded land was open oak woodland or savanna.”

Why are the oaks important?

“There are two reasons why this is important today, and why many people are working to restore our open oak woodlands. First, oaks and hickories produce large nuts that are very high in fat and protein. Animals depend on these as a major food source throughout the winter. Surveys of the use of tree species by animals show that oaks and hickories – and oaks in particular – are eaten by something like 200 species of animals. If the oaks disappear, those animals are going to decline too.

“Second, because oak woodlands were so open and sunny, there was a diversity of understory plant species that survived only in those open oak woodlands. Some of these understory plants also grew in the prairie, but others were limited to these open oak woodlands with their intermittent, speckled sunshine. So, you have both animal species and plant species depending on open oak woodlands for their perpetuation.”

How are controlled/prescribed fires conducted?

“In some areas of Iowa, there are now trained personnel who know how to do prescribed fire. They do it well, and they do it safely. My fire is going to be done by a small business called Transition Ecology. They have a four-wheel all-terrain vehicle with a 60-gallon water tank on the back. We’ve created paths through the woods so that they can put out any unwanted fires with the vehicle. We’re going to do a “backfire,” one where the fire actually burns into the wind, so it’s going to be a slow fire. It should take a couple hours to burn the five acres.

“We will also have developed firebreaks beforehand, especially around our house. We’ll make sure that the smoke will blow away from the road. We’ll put warning signs on the road and we’ll contact the fire department.

“It’ll actually take longer to do what they call “mop up” after the burn than to do the actual burn. They’ll go around spraying any smoking downed trees after the burn with water, and then they’ll watch the woods for a while. I may need to stay home for a few days just to make sure that there are no lingering sparks.  Sometimes, when the temperature drops toward the end of the day, the fires go out, but then the next day, as the temperature rises, smoldering fires can start up again.  We’ve figured out how to do prescribed fire so that it’s well managed and safe for us, and a benefit for Iowa’s fire-dependent natural communities.”

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