Wading Right In by Catherine Owen Koning & Sharon M. Ashworth

Author:Catherine Owen Koning & Sharon M. Ashworth [Koning, Catherine Owen & Ashworth, Sharon M.]
Language: eng
Format: epub
Publisher: University of Chicago Press

Siren Song of the Bottomlands

A few states away from Jacques’s bat study in Indiana, wetland ecologist Frank Nelson spends his days piecing together the ecological puzzles of the Mingo River basin in southeastern Missouri. The braided channel of the Mississippi River historically ran through this area, before changing pathways and leaving behind thousands of acres of wet bottomlands, which were kept watered by flow from the Castor River. In 1918, a diversion channel was built to shunt the water off these bottomlands thirty miles west, to the Mississippi River. Eventually, over six thousand miles of drainage ditches were built, drying out the lowlands for farming.

In the 1940s and ’50s, some of the wettest areas became part of the Mingo National Wildlife Refuge and the Duck Creek Conservation Area. “Much of the culture around here is all about hunting” Frank explains. “So the managers emphasized habitat for waterfowl.” They created wet basins containing open-water marsh, lakes, and forested swampland known as “green tree reservoirs” in the Duck Creek Conservation Area, all of which are important habitat for pintails, teal, mallards, shovelers, and other ducks and geese. “Back fifty or sixty years ago, when these areas were developed, the engineers didn’t think about how water flowed across the landscape; they just put some levees down, made it a rectangle, and they put the water-control structure in the lowest place. But the water just sits at the lowest spot and doesn’t get the water off of the trees.” So the trees drown, and the creatures that depend on the forested wetlands lose their habitat. Part of Frank’s job has been to improve the water management so that a greater diversity of natural communities can survive. Using handheld GPS units and lots of swamp walking, Frank and his colleagues mapped out the detailed contours and curvatures of the land, trying to figure out where the water used to flow and how changes in water levels would affect the plants and animals.

Very small differences in elevation—less than a foot—make a big difference in the type of forest that grows in these lowlands. “Because the rivers have shifted and moved over time, you have these small landforms, these little ridges; they may only be a foot or two, but the forest community has distinct changes along these ridges. There may be upland species like cherrybark oak [Quercus pagoda] and willow oaks [Quercus phellos], water hickories [Carya aquatica], even pawpaw [Asimina triloba] and hawthorn [Crataegus spp.].”

Walk a few inches downslope here (as well as in other southern sections of the midwestern and mid-Atlantic states) and the true wetland trees take over, such as the bald cypress (Taxodium distichum), a coniferous tree with rows of short needles and incredibly rot-resistant wood. Like the tamarack, this conifer sheds its needles every year, making it a deciduous conifer, which sounds a lot like an oxymoron but is not. Unlike pine and spruce, some cone-bearing trees drop their needles all at once. Thus the bald cypress is depilated each fall. Alongside the cypress, tupelo trees are a common companion.

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