Wet and Wild in Iowa's Fens

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by Bill Witt

Like countless workers the world over, Rebecca Kauten likes to display a picture of her "kid" on her desk at work. And in common with other parents, she recognizes her namesake is a complex individual that deserves the right to be itself: by turns gentle, beautiful, bouncy, always growing, surprising, stubborn: "You can't really make comparisons with anything else-it just doesn't like to be pigeonholed."

Kauten laughingly refers to her "kid" as "it" because the picture beside her computer screen smiles with flowers, ferns and endangered plants. It's a fen-a rare, highly specialized kind of wetland.

"Becky's Fen," as it's officially called, has flourished on what's now her parents' farm south of Fayette for an estimated 5,000 years ("pretty old to us-but still young as far as Mother Nature's concerned," Kauten says). The name is a loving tribute to a daughter's persistence in persuading her father to protect and permanently preserve it.

What is a fen?
Fens are places where mineral-rich groundwater flows out onto the land surface, creating, in the words of John Pearson of the Iowa Department of Natural Resources (DNR), "constantly saturated, but not flooded, habitats." People often confuse bogs and marshes with fens, Pearson explains, but while marshes are often flooded, with pools of stagnant water, "Fen waters are spring-fed and always flowing, at least beneath the surface of the peat or muck substrate."

In addition to steady outflows of groundwater, fens are typically found on hillsides and terraces of streams or rivers-in association with deep deposits of "muck-type" soils, usually Palms or occasionally Houghton, muck.

Fen survey
These two common denominators enabled Pearson and his DNR colleague, botanist Mark Leoschke, to use soil maps and aerial photos to identify possible sites when they began what they "naively thought would be a one- or two-year survey" of Iowa's fens. That was in 1986, and at the time only a handful of fens had been located and studied, along the western margins of the Des Moines Lobe landform of northwest Iowa and the Iowan Surface landform of eastern Iowa.

Although their survey activity peaked around 1991, Pearson and Leoschke are still at it today. Using soil surveys, they identified 1000 potential fen sites. By studying aerial photos, they found that 40% of these sites were destroyed and another 30% were mostly destroyed or too small to merit further study. They field-checked the remaining 300+ sites and found about 25 "good" fens, plus another 60 or 70 that still contain some high-quality native plants.

Fens as refuges
Intact fens' scarcity, coupled with their usually small size and unique soil and water characteristics, make them refuges for some of Iowa's rarest plants and animals, Leoschke notes. Among the over 200 plant species found on fens, about five percent are listed as threatened and endangered.

Species associated with fens include Kalm's lobelia, Grass of Parnassus, Hooded ladies tresses and Spring ladies tresses, Small bladderwort, Fringed gentian, Bog bean, Beaked rush, Whorled nut rush, Arrow grass, Bog willow, Sage willow, and Bog birch.
Numerous species of butterflies and moths call fens home, including the strikingly beautiful, and rare, Baltimore checkerspot. Fens and their margins also provide nesting and feeding habitat for such birds as sedge wrens, snipe and sora rails, as well as Iowa's most popular game bird, the ring-necked pheasant.

Western vs. Eastern Iowa fens
Continuing research has revealed that eastern, or Iowan Surface, fens may differ in several ways from Des Moines Lobe fens. The Iowan fens are considered younger by hundreds or thousands of years, which may account for their lack of distinct zones of specialized plant growth. The geology of the western Iowa fens contributes to their "steady" rates of moisture recharge and discharge, regardless of rainfall, while their eastern Iowa cousins' water flows tend to be more sensitive to rain and drought patterns.

Differing mineral concentrations of the eastern and western fens' waters may also help account for distinct variation in about 20 percent of the plant species between the two types. The net result is that eastern Iowa fens harbor 22 species of trees and shrubs, while western fens have only 2. Eastern fens also feature a number of broad-leaved, non-woody plants (forbs) that are absent or rare in western fens, including Marsh and Sensitive ferns, Swamp saxifrage, and Marsh marigold.

Forested Fens
Soil maps have led researchers to hundreds of so-called "prairie fens." However, John Pearson notes this method doesn't help pinpoint the least-studied fens, those that occur in forests. "Those super-saturated muck soils just aren't mapped when they're under tree cover," he explains. Of the handful of forested fens that have been identified, the best-known is Hanging Bog in Linn County, which features carpets of Impatiens, Marsh marigold, and Skunk cabbage in its discharge zone at the base of a small bluff.

"The hanging bogs, or forested fens, need a lot more study," Pearson says, "but we usually won't know about a forest fen unless somebody tells us it's there. That means we need landowners and other interested people to guide us-and we hope they will!"

Saving a fen
Rebecca Kauten was "nine or ten" she recalls, when she signed on as one of Pearson's and Loeschke's allies in the effort to save Iowa's fens. "My dad was pretty frustrated with 'that big wet spot,'" she says. "It kept sucking down tractor wheels when he drove too close. He couldn't plow it, couldn't grow anything on it. He kept scheming ways to try and get rid of it. And the fen kept finding ways of defeating him."

And then, "One day John (Pearson) and Mark (Leoschke) showed up and asked if they could take a look at it. My dad and I went out with them, and they got excited, pointing out all the neat things they were finding."

The site visits continued, and as young Becky listened in on the botanists' reports to her father, she was inspired to "go out and study for myself what they were talking about." And as her knowledge and enthusiasm for the fen deepened, her father's skepticism and frustration softened. Finally, after about four or five years of scientific reports and daughterly persuasion, he called in the Fayette County Conservation Board (FCCB) to help draw up a permanent conservation easement. The terms keep ownership in the Kauten family, while DNR holds the easement and FCCB is the land management partner. A state Resource Enhancement and Protection (REAP) grant helped fund the project, finalized in 1994.

"Dad's attitude completely changed," Rebecca Kauten says. "He came to think of his old nemesis as something that's rare and precious, and that we're privileged to own and protect. Now we'll go visit other people's fens, and it's like the farmers driving the back roads, checking the neighbors' fields for weeds and straight rows-except my dad will walk around on this new fen for a while and then he'll lean over and whisper, 'This one's OK, but we've got a lot better stuff growing on ours.'"

Want to learn more about Iowa's fens?

The original magazine article is illustrated by several photos by Bill Witt. To receive a free copy of this issue, e-mail Cathy Engstrom, Director of Communications, or call (515) 288-1846. Request the Summer 2002 edition. INHF projects and research are made possible by our members. Join us!