Chapter One of a wetland story

DSC_0516Steve Laughlin, the owner of Pleasant Creek Farm near Barnes City (Mahaska County), had read about my 99wetlands quest and graciously agreed to host my Limnology class this week. We were able to observe biota, collect samples, and talk about the engineering and management of constructed wetlands—a welcome educational experience. But that’s just the beginning, because we’re still in Chapter One of a wetland story.

The story might include a Preface stating that this property  already contained valuable habitats of tallgrass prairie, oak savannah, and ponds. As is often true on private lands, the property serves multiple conservation and recreation functions, including hunting and fishing. Specific provisions are provided for training hunting dogs. A picnic shelter up on the hill looked like a pleasant place to watch the sunset and observe wildlife.

DSC_0526A low spot on the property, not far from a stream, already hinted at wetland conditions. Steve decided to work with Nature, and recognized that existing hydrology could be augmented by an embankment, holding back water in a wetland basin. This structure really impressed me with its size…I sheepishly hinted that it must have been a bit of an investment. Steve laughed at my awkward hinting and mentioned having a contractor with great skill with whom he has a good working relationship. It doesn’t hurt that Steve is himself a retired civil engineer! So he built a substantial water control structure, and a good thing too: muskrats like to dig into these, and are notorious for causing failures. This embankment should be able to withstand those burrowing rodents.

DSC_0525So in 2011 the wetland was established, and the story begins. Steve told us that other than just a few flowers, he has added no plants or animals. Yet he has subsequently observed various waterfowl, wading birds, and raptors. They suggest prey are present, and various fish and invertebrates are in the water; they in turn must graze. The site has filamentous green algae and several species of Pondweed (Potamogeton) in the water, and emergents around the margin such as Arrowhead (Saggitaria), Rushes (Juncus), and Spikerush (Eleocharis) to spport the animals. In short: we have a food chain.

The drought of 2017 has provided an interesting plot twist to our wetland story. For the very first time at this site, areas of the wetland have exposed mud normally covered by standing water. Such a “draw-down” is actually a natural occurrence,  key to the ecological model of cyclic succession. Wetlands have a drawdown during the dry period, seeds thus exposed to air germinate and the plants grow, and the wetland experiences a significant period of plant cover and production. Eventually conditions return to open water until the next drawdown when the cycle begins again.

DSC_0530As the class began their sampling, I asked them to consider how delineating a natural wetland compares to assessing the development of a created wetland like this one. What features are diagnostic, indicating “this is (legally) a wetland” or “this is a low/medium/high-quality habitat?” They have an assignment on the topic, so I won’t say more. But such questions clearly challenge us to develop our ecological theory, our official classification and regulation, and should inform management practices.

Which brings us to the next chapter in our story. Steve generously offered to host Central College students and faculty in the future, at this wetland and on other parts of the property. I am delighted to undertake what I hope will be a longitudinal study, observing this wetland develop. Surely the system will have more biological production (plants, animals) over time. But which species should we expect sooner, and which may take a while to appear? Yesterday in Ecology class I described so-called “assembly rules,” pondering if an ecological community must have a certain successional pathway to develop a particular functional type. How would the chance appearance of certain insects or worms or submersed plants, adhering to a bird’s body and thereby entering the wetland, change the narrative of our little story?

Time will tell—we’ll have to read the story as it is written over coming years, and be patient in the meantime. The various characters in our story—water chemistry, soils, wildflowers—will each have a part. But I already know the hero: Steve has provided the pages of the book, and that makes him part of the story, too. As the 99wetlands project continues, I hope to highlight the work of people like Steve who recognize the beauty and value of Iowa’s wetlands. Such “wetland heroes” will help us restore, preserve, and enjoy our amazing wetlands. Thanks for joining us on the journey!

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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