Summer Burn. Illinois Beach. August 3, 2023

 

Here's what it looked like the day after the burn:

Here's what an unburned part looked like:

Really?

They burned up stuff like this?

And it was a good thing?

Yes, it was. 

Parts of Illinois Beach Nature Preserve have been getting too brushy?

Is there an objective standard for what "too brushy" means?

Once again, yes there is. For more detail, see Endnote 1.

This photo shows death by shade. Here excessive numbers of young oaks and sprawling grape vines have largely killed off the turf of (rare) grasses and wildflowers on which the biodiversity of the Illinois Beach savanna depends. 

Oaks and grapes are good. But in the absence of adequate fire, they can become pathological to the ecosystem. 

Illinois Department of Natural Resources biologist Melissa Grycan led the six-acre burn in this 1,080-acre Nature Preserve. See map below: 

The burn started at the Dead River (south of the Dead River Trail) and burned to the Dune Trail and the east edge of the savanna. The photo below shows the south firebreak by the Dead River.

The savanna at Illinois Beach is mostly on old beach ridges and dunes. The sandy soil makes it likely that many patches will be so thinly vegetated that the fire will skip them. Here two plants of purple prairie clover, in bloom, were missed by the fire while a nearby young black oak was top-killed, as were other nearby plants. 

Summer fires are unusual on conservation land these days, but they shouldn't be. Explaining them to a skeptical public can be a challenge, but they can be very good for the ecosystem. For millions of years when all burns were started by lightning strikes, they could occur whenever dry lightning was possible and the vegetation was dry enough to burn. For example, on a day like August 3rd. 

Summer fires can be especially valuable for areas where too much brush has accumulated. Most controlled burns these days occur in late fall, winter, or early spring. Such dormant season burns set back brush, but much less than summer burns. When leaves have fallen, most of the chemical and energy resources of the shrubs and trees are stored in the roots. During the growing season, much of the plants accumulated resources are in the bark and leaves. The summer burn cuts off those resources, and the roots (which are all that survive) need to start over with much diminished resources. 

The photo above shows another spot along the firebreak. The flowers in bloom to the left are purple prairie clover and flowering spurge. The same were probably blooming to the right. They'll come back just fine after a rainstorm or two. Most herbaceous plant species of prairie and savanna are well adapted to surviving summer fires. 

How about animals? Most run away, or fly away, or go underground. A great many non-flying insects are killed, but they'll reproduce bountifully in the reinvigorated (and less brush-suppressed) ecosystem. 

Part of this prickly pear cactus looks burned and part looks fine, including about fourteen "pears" that will be popular with some animals later on. (We humans are not allowed to taste this fruit in this legally protected Nature Preserve.)

In many savannas, trees are well separated from each other. Here, arguably, too many trees were vying with each other. The big tree here should be fine. Many of the little trees will be top-killed or may die outright. That would be a good result in some areas here. 

Two final photos:

Here, with eastern towhees and bluebirds singing in the background, a part of the savanna appears to thrive following previous burns:

And out in the prairie ...

... we're reminded of what an extraordinary place this is. Savanna in the background. Prairie in the foreground. And a meadowlark singing to us as the cell phone camera snapped. 

If you're in the mood, please join us for stewardship and inspiration any Saturday at 9 AM at the Nature Center parking lot. We'll venture into the ecosystem from there. 

Endnotes

Endnote 1. What does "too brushy" mean? And why did parts of Illinois Beach get that way? 

Illinois Beach Nature Preserve is one of the highest quality and most important biodiversity reserves in the midwest. That's because of its very high-quality natural communities, which are known as such because of the great diversity of mostly-rare plants and the animals that depend on those plants. In the savanna and prairie ecosystems here, the biodiversity is dependent on the diverse turf of grasses, sedges, and wildflowers. When burns are insufficient, alien and native woody plants grow so dense that the ancient diverse turf is killed by shade. Where there had been twenty rare plant species per square yard, that number gradually gets reduced to ten, then perhaps one or two common species of plants. The animals that lived off those plants are then gone too. "Too brushy" is not philosophy or aesthetics. It is measurable and "life or death" for the health of the ecosystem. 

When the principal grassy fuel for the fires is gone, recovery is difficult. The savanna will not "succeed" into a natural forest, because the species that make one up are not here. So a depauperate and degraded savanna is all that survives unless resources are available for a lot of restoration.

"Fire-deprived" patches develop at Illinois Beach in part because of the care that has to be taken by burn managers to protect human health and air quality and certain endangered species (which have ways to deal with fire when they're in adequate numbers, but not in their reduced numbers today). 

We look forward to studying the results and expect to watch the healing recovery of colorful beauty and natural diversity in this summer-burned patch. 

Acknowledgements 

Thanks to Rebeccah Hartz for good edits, suggestions, and questions.