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Environment

A unique wetland in northwest Iowa was turned into farmland. A conservation easement is reviving it.

120921-fen-restoration
Rebecca Kauten
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Throughout this past summer, they saw plants they expect to live in most wet prairies. They're waiting for the types of plants specific to fens to show up.

A unique wetland in northwest Iowa was once drained, then heavily farmed for 70 years.

Now, it’s showing early signs of a return.

In the early 1990s, botanists at the Iowa Department of Natural Resources wanted to locate fens across the state. Regular wetlands are usually fed by surface water from rivers, streams and lakes, but a fen is a type of wetland fed by groundwater.

The botanists knew of three fens in northern Iowa, but they soon identified about 200 more around the state.

“A lot of these were highly degraded, very small, partially tiled, overgrazed, next to crop fields, have had a weed invasion problem,” said John Pearson, one of the DNR botanists who did the surveys. “But there are also quite a few really nice ones.”

But Pearson and his colleague overlooked one fen in particular near the northwest Iowa town of Estherville in Emmet County, thinking it was “completely gone,” he said.

Long before the DNR’s efforts to track the fens around the state, this particular site known as the “big fen”, one of the largest known fens in Iowa, piqued the interest of early 1900s botanists for its rare flora. The fen was one of only two sites in Iowa to have hooded ladies’- tresses, a perennial orchid.

But in the early 1950s, two surface ditches were cut across the estimated 80- to 100-acre fen. Water from the saturated soils went to the surface and into the ditches and drained into the Des Moines River.

The land was tilled and put into production for row crops, but a remnant of the fen under an acre survived, leading to interest that it could be restored.

The Neppl family, which owns land on a part of the fen, decided they were interested in protecting the site. The U.S. Department of Agriculture’s Natural Resources Conservation Service used a legal agreement known as a conservation easement in 2016 to purchase the property containing a portion of the fen.

It’s probably going to take 100 years. We’re 1 percent of the way into that project.”
John Pearson, Iowa Department of Natural Resources

It took about two years to close on the easement with the landowners.

Then last year, the NRCS disabled the drainage to undo the impacts from those ditches and farming. John Paulin, a wetland restoration specialist with the NRCS in Iowa, said there are just under 1,700 conservation easements for 195,000 acres across Iowa, but “nobody had all of the answers to how to best restore a fen,” he said.

There isn’t a lot of published research on fens. So the NRCS worked with the Iowa Department of Natural Resources and the Iowa Lakeside Laboratory to return the fen to its original condition and track the progress of that restoration.

Once the drainage was disabled, scientists noticed something remarkable. Groundwater flowed back in almost instantly.

Monitoring the fen’s revival

Researchers at the Iowa Lakeside Laboratory in Milford wondered how much of the native plant community and the site’s hydrology could truly return.

Throughout this past summer, they saw plants they expect to live in most wet prairies, said Rebecca Kauten, the scientist in residence. Drought in the last couple summers played to the fen’s advantage, keeping weeds from growing and invading it.

“You can’t always count on that,” Kauten said. “But in this case, it really worked to our advantage that the hydrology was what was really driving the vegetation more than atmospheric conditions.”

But the researchers are waiting for the types of plants specific to fens to show up. They're unsure if they will return and how long that could take.

Still, the activity the team noticed last summer is a positive sign.

“We only had one full growing season,” Pearson said. “So we’re early into this, folks. It’s probably going to take 100 years. We’re 1 percent of the way into that project.”

The Iowa Lakeside Lab will continue to monitor the fen’s revival. Paulin said the NRCS will check on it annually and will work with the Neppl family to fund additional projects as needed.