Fractals in the Wetland

DSC_0252It’s surprising what my wandering mind will stumble upon during my wetland wanderings. On a recent walkabout at Littlefield Recreation Area in Audubon County, I was thinking about fractals, of all things! It actually made sense in context, and may be helpful to bear in mind when thinking about habitats and the living things therein.

Fractals are a concept from mathematics, applicable to art and ecology and many other topics. The idea is that a geometric pattern repeats itself across scales: a certain shape is contained within a larger version of that same shape, and also has within it smaller versions of that shape, and so on. They make beautiful and interesting designs for illustrations, but I wonder if they might also apply in an ecological sense for wetlands?

DSC_0258If any ecosystem could be a fractal, wetlands are likely to do it. An aerial view of Littlefield shows a variety of watery habitats, from the 70-acre (28 hectare) lake, to a pond, ditches or swales, wetlands, streams, and various connections between all of them. I’m unfamiliar with this site, but such places sometimes have high water spreading across the land and submerging it all, or dry conditions where low wet spots are isolated or even dry up entirely. The variable hydrology of wetlands makes them larger, smaller, connected, disconnected…perhaps a fractal pattern across the land, and over time?

The idea of “winking patches” in landscape ecology, where habitats appear and vanish, would have profound implications for organisms. As one example, think about frogs and toads. The concern about “amphibian decline” has a lot of attention as populations, and whole species, are in danger of being lost forever. But having habitats where predators or diseases can’t establish, because of their ephemeral nature, can be really important. The long-term stability of an amphibian is accomplished through short-term, unpredictable or temporary habitats.

DSC_0259The ponds and wetlands and lake may connect by surface water during wet times, and groundwater at other times. But algae and bacteria and seeds will blow around the site at other times, too. Animals will hop and crawl and slither and fly between the various habitats. And it’s all part of a larger network of inter connected ecosystems, too. Streams flow onto this property, are dammed to form ponds or lakes, and then release to contribute to streams and rivers running downslope from here. A map of Audubon, like many Iowa counties, has wiggling blue lines joining together here and there, giving an overall impression of a tree: the aptly-named “dendritic drainage” (from the Greek word for tree, Dendros).

So although the old adage may be true that “we all live downstream,” that’s only part of the story here. We all live in a fractal landscape, perhaps. Thinking about the little habitats, and the larger landscapes to which they contribute, and the connections between these fractal elements, may help us both better appreciate and care for our wetlands.

Perhaps that would be a worthy resolution for us. (Happy New Year!!)DSC_0254

Author: Paul Weihe

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

2 thoughts on “Fractals in the Wetland”

  1. I really like the fractal thinking. It reminds me of a talk I heard years ago in which the pre-Euro-settlement Midwestern landscape was described as an ever-changing mosaic in which the oak savannas kept advancing into the prairies and then retreating and then advancing again, depending on fire and rainfall patterns.

    And I’m happy that Littlefield is fairly large by Iowa standards. Some kinds of ecological patterns only have room to express themselves on larger parcels of land, and Iowa drainage laws can especially limit what is allowed on smaller parcels that contain creek segments.

    Liked by 1 person

  2. I appreciate the comments. Truly, we see a dynamic landscape when we allow ourselves to think big and think small, both in space and time. It’s hard to do with our human frame of reference, right…?

    Like

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