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Not quite a pure water creature and not fully at home on land, beavers represent a classic "edge" animal. Pictured is the sometimes drastic way in which beavers can alter their environment. Keith Corliss

Memories of college class still relevant

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The passing years tend to dull memories somewhat. This is no less true with our schooling as well. I probably couldn't pass a statistics test today nor could I stand a chance in organic chemistry. But certain classes taught by certain instructors somehow defy this notion of lost information. For whatever reason, I actually remember a few of these classes with some clarity. I think it's the right mixture of an interesting subject, a dynamic and capable instructor, and course material that grabs the student a certain way.

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So it was with Dr. Gary Clambey's Plant Ecology class nearly 30 years ago.

I was thinking about Dr. Clambey's class recently. More specifically, a certain biological concept he spoke about which was new to me at the time; something called the "edge effect." My textbook long gone, I did a little Internet search for the proper meaning of this phrase, or at least the one I was looking for. No, it wasn't the latest cool thing from Adobe Photoshop. Nor was it a new-age diet fad. Finally, the American Heritage Science Dictionary came through: "The influence that two ecological communities have on each other along the boundary (called the ecotone) that separates them."

Sounds simple enough. But contained within this simplicity are robust biological interactions. The definition goes further, "Because such an area contains habitats common to both communities as well as others unique to the transition zone itself, the edge effect is typically characterized by greater species diversity and population density than occur in either of the individual communities." Now we're getting somewhere.

What this means for we lay folk is this - if we want to see more plants and animals, hit the edges. What is an edge? Well, anytime things change. A clearing in a forest where it opens to a meadow is an edge. A prairie wetland changing from cattails to dry grasses is an edge. No more drastic example of an edge can be found than a beach line where continent meets ocean.

At these and every other transition zone, plant and animal communities meet in a sort of uneasy collision. And this is where your odds of seeing things are greatest just by sheer numbers alone. Sure there are birds which confine themselves to the middle of the forest while other species prefer meadow habitats. But by placing oneself on the edge of the forest/meadow ecotone, a person has maximized the chances of seeing birds from both ecological communities.

It's not just biologists who are aware of the edge effect. Fishermen and hunters know it well too, although they may not have defined it as such. When encountering the prospect of fishing a large unknown lake where does the fisherman go? Not to the center of the lake but to the weed borders or to the drop-offs. In other words, the edges. Similarly, the deer hunter puts up his tree stand not in the center of the woods, but usually near the spot along a trail where the deer transition from woods to open feeding areas. Again, an edge.

The weird part is it's not just the animals and plants which gravitate toward edges, but we do too. How many folks in this region have a lake home right on the edge of water? In a similar fashion the largest cities in the U.S. are along the ocean. Surely ease of water transportation accounts for a large share of this but might there be just a desire to live on the edge? Or think about the early settlers to this area. Once the pioneers had built a cabin and turned the prairie soil, most planted trees. Yes, it served as a block against the relentless wind but might it also have met a need to break up the sameness of the prairie landscape, a desire to create a little edge?

I just checked with NDSU and Dr. Clambey is still teaching. Teaching, undoubtedly, with the same tireless energy with which he's led students for years. He'd probably be pleased to know a student from many years ago remembers his class fondly; even recalls a specific concept. Sure, I'd likely fail a weed science test, but at least I can meander through the idea of the edge effect. Thanks Dr. Clambey.

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