Boone County: Harrier Marsh

“But Paul,” you say. “Love the travelogue, but why don’t you tell us about your research?” So glad you asked!

I visited this site along US Highway 30, as part of reconnaissance for an investigation of the invasive exotic wetland plant, Purple Loosestrife (Lythrum salicaria). I did my Master’s thesis project studying competition between Loosestrife and our own home-grown Broad-leaved Cattail (Typha latifolia). That was in Michigan, in 1991! A lot has changed since then, and my students & I visited Harrier Marsh site and other Iowa sites, and conducted lab and greenhouse work, to see the status of Loosestrife in Iowa, today.

loosestrife
Ah yes, my old nemesis…Loosestrife, we meet again. Photo not taken at Harrier Marsh!

Based on a database of observations provided by the Iowa DNR, I knew that Loosestrife was reported here at Harrier Marsh in 2002, some 100-1000 plants. I made my first visit here in 2013, and noted no Loosestrife plants (except possibly a couple dead, standing individuals from the previous year; ID questionable). What happened to the Loosestrife in the interim? Successful control efforts, that’s what! Iowa conservationists had released several species of insects (imported from the plant’s home range in Europe) to eat the plant. In my travels around Iowa, I found greatly diminished Loosestrife, and often what I did find was often under attack by the insects.

Fast-forward to today. I look across Harrier Marsh and find…a sea of cattails: the plants go on and on. Not a single Loosestrife to be found, and precious little other plants either. It’s Cattails, shore-to-shore.

 

As an ecologist, I can’t help but wonder about the implications of a wetland converting to (what appears, at least) to be a monoculture of cattails. Are other plants in there, hidden by the tall and dense cattails? What are the consequences for wildlife, of a change in the plants growing here?

DSC_0107
The Yellow-headed blackbird, Xanthocephalus xanthocephalus. Looks cool, perched high above his patch of marsh. Sounds cool, too—rather like the horn on an old jalopy! Don’t believe me? Listen for yourself.

Assessing ecosystem function is no small task. What I can say at this point, is that Harrier Marsh has a lot of blackbirds: Red-Wing of course, but also quite a few Yellow-headed blackbirds (seems to be a good year for them in Iowa). I was excited to see both a muskrat and a mink. I noted signs of crayfish burrows. It’s A Good Sign to see several examples of animals present.

The story of what plants grow where, and what it means for the ecosystem, is a question I hope to consider in the future; it’s the sort of wetland research I might pursue. If so, 99Wetlands will tell you all about it! Stay tuned!

Author: Paul Weihe

Associate Professor of Biology at Central College, traditional author (Textbook of Limnology, Cole & Weihe, 5th ed.; Waveland Press), and now...blogger!

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