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Follow That Fire!

On one beautiful day in May, I took some time to traipse back and forth on the south unit prairie at Motor Mill.

It has always been one of my favorite prairies on any of our sites; it’s got a good balance of forbs and grasses, few invasive species, and from the right angle prairie occupies the entire horizon – no buildings, no roads, no power lines, no trees. Nearly every visit yields a turkey or deer scuttling into the adjacent woodlands as I wade through the grasses, and bobolinks whistle to alert the flock of my presence.

But it’s a tricky one to burn; a large neighboring CRP field presents a significant hazard if the wind isn’t right, and strong southerly winds are few and far between. Luckily, this year, we got the chance to burn both fields simultaneously – we and the neighbor felt a little safer knowing the burn couldn’t escape to anywhere that wasn’t going to be black anyway.

The last time this prairie burned was May of 2019. I was a much different person then, in terms of prairie experience, so while I explored the post-fire landscape I didn’t have the personal history with it to know whether the fire “worked.”

This time around, I’m a little older and a little wiser. I’ve combed it over enough times to know what’s growing where – the stands of spreading dogbane, the spot where the cottonwood seeds seem to collect, the raspberry thickets.

After five years, invaders like multiflora rose can develop quite a canopy. They cast enough shade to leave a “shadow” after the burn; multiflora rose top kills very easily after a fire, and you can see the bare spot under the naked stems.

But if you look closely, you can see that the fire didn’t actually deliver a knockout. A few weeks later, you'll see resprouts developing right at the base of the shrub. So this time around, I’m using the relatively bare conditions left with the duff burned off to head back and deliver a right hook to follow up the fire’s uppercut.

It's a part of the prairie management process that often gets overlooked, possibly because a lot of the basic talking points kind of oversimplify how fire works in these systems. Part of the "elevator pitch" for planting prairie is that it's low-maintenance: burn occasionally and it'll stay prairie. Many people get frustrated, because the elevator pitch usually includes some version of “fire keeps the trees out,” or “fire controls woodies,” or at the most misleading, “fire kills trees,” only to find that two years after the burn the trees are right back.

Few tree species will die from one single fire – unless it’s remarkably intense. Cedar makes a notable exception, though even those will only die if the fire consumes enough of the leaf material for the tree to stop feeding itself.

Otherwise, most fire-intolerant (and many fire-tolerant) woody species in a prairie will simply get caught in a “fire trap,” i.e. they’ll sprout back and grow until the next burn, and develop a kind of shrubby form.

More susceptible species might give up after a second annual fire, but a lot of landowners are reticent to burn annually, and with good reason – annual or biennial species can take a serious beating with too high a fire frequency.


All this to say nothing of invaders that don't mind fire (Canada thistle), or even worse, love fire (Sericea lespedeza). Repeated defoliation through the growing season, by combining fire with mowing or grazing, has a better chance to fully kill undesirable species. But since we don’t have livestock, and the deer won’t eat the plants I tell them to, and mowers paint with a broad brush, I’m trying a little more targeted approach.

This year I’ve devoted a lot of time to revisiting our burn areas and hitting the resprouting rogues gallery with herbicide. I know a lot of earth lovers’ eyes start to twitch at the mention of applying toxic chemicals, but stewardship is all about managing collateral damage – every choice has winners and losers, pros and cons, risks and rewards.

Timing is everything to manage those risks. Once the green starts to poke back through the black, there’s a short window where the typically-dense prairie offers enough breathing room to apply a very small amount of chemical to a very small area, and minimize the civilian casualties.

Revisiting the burn a month or so later also provides an opportunity to see what’s really in the prairie. By the end of the growing season, much of the shorter-statured species will disappear beneath a blanket of towering grasses. And so it was that I realize we do have prairie corepsis, a beautiful little yellow flower, growing at Motor Mill. We do have prairie phlox. We do have a few tiny shrubs of leadplant.


More and more needles come out of the haystack. Blue-eyed grass, copious amounts of culver’s root, ironweed. How have I never noticed these before?

As much time as I spend out here, I’ll never match the time investment of the local whitetail population. I get a little bit sad that a lot of the more aesthetically-pleasing species seem to get nipped off before they can really get that postcard look.

On the other hand, we grow prairies for wildlife (well wildlife and, like, 65,000 other reasons), and I can’t go getting mad every time a critter enjoys some of the nosh provided by wild spaces.


The nectar-lovers end up with a little bit less of a menu, but at least the host plants remain for moths and butterflies. The structure remains for grassland birds, reptiles, and rodents. The roots remain – perhaps with a little more vigor, even – to build soil and capture runoff.

In the end, I have to celebrate the presence of these species, if not their blooms. I have to be grateful for the fire and the opportunity it provides not only to identify their presence, but to hopefully enhance their population by knocking out some of their competition.

And I have to hope that whitetail hunting remains an Iowa tradition, and that everyone gets all their tags filled every season. Looking Back

Field trips, everywhere you look! Osborne positively buzzed with activity, with hundreds of students from all over Iowa, Wisconsin, and Minnesota descending upon our trails, wildlife exhibit, and nature center to squeeze the last drops out of their school year.


But we also found time to host a few public programs. Naturalist Abbey hosted a May Day hike here at Osborne, on the lookout for birds, blooms and mushrooms. With the ample rains and mild temps this spring, the group found plenty of all three! On May 17th, 5 intrepid hikers joined me for a savanna saunter on the Well’s Hollow trail at Bloody Run. We rambled from ridge to ridge, marveling at the phenomenal display of spring wildflowers afforded by the beautiful remnants at one of my favorite sites in Clayton County.

On May 24th, the Turkey River Safari officially launched for the season! Stop by Osborne, Gilbertson, or the Fayette County Tourism office to pick up the materials for this self-guided adventure up and down the Turkey River.

Finally, on May 30th, the O.W.L.S. took a visit to the Norman Borlaug Boyhood Home. This Nobel Prize Winner who developed disease-resistant strains of wheat saved billions of people from starvation. Sadly, he came along about 100 years too late to save the wheat crop at Motor Mill, but his story remains fascinating.

Behind the scenes, we’re getting ever closer to completing construction on the new campground at Osborne! Crews were in this month pouring pads, and installing utilities. Despite the rains, they got a lot done and we’re very much on track to have it ready to go in the summer of 2025. We hope to see you there!

Looking Forward

Free fishing weekend is coming up June 7-9th, and Backbone State Park will host a fish derby on June 8th to kick your summer off right. Our naturalists will be on hand with a few slippery, slimy critters, so you’re guaranteed to at least encounter some cool aquatic animals even if your lines aren’t tight.

On June 18th, O.W.L.S. will take a visit to Turkey River Farms and see one of the finest organic farming operations around. Pete and Natasha, with their son Joe and a small cohort of volunteers, have been providing Clayton County residents with delicious, fresh veggies for more than half a decade, and it’s a fascinating operation to behold.

June 21st will see our first summer camp of the season, River Rats – rivers and ponds hosted here at Osborne Park for budding naturalists ages 10-15. We still have a few spots left, so check out our page on MyCountyParks.com to register today.

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