Nature’s Engineers? Or Nature’s Despoilers?

I talked this past weekend with a rancher who was trapping beavers. Their dams have flooded some of the land he hays, taking away feed from his cattle.

I like trees and I like cattle. In my personal experience, that leads — inevitably and unavoidably — to being none too fond of beavers. If I were that rancher, I’d be going after the beavers, too.

Yeah, I know. They’re “nature’s engineers” in popular parlance, “ecosystem engineers” in eco-friendly circles and cuddly, wisecracking hipsters in cartoon comedies. We’re all supposed to love beavers.

But I’ve seen them do massive damage along North Dakota’s Sheyenne River, cutting down 150-year-old oak trees to clear the way for other, faster-growing trees species that the rodents prefer to use in their dams. True, the ruined trees are replaced eventually by new ones, and so you can argue the long-term result is a wash. But the short-term result is a loss, especially for people like me who enjoy oaks.

I’ve also seen beavers build dams that flood pastures, cropland and, especially, low-lying hayland. I’ve seen ranchers, who had been relying on that lost hay, struggle to find replacement feed.

Hey, I understand that beavers can bring benefits. Their dams can reduce downstream flooding and bank erosion, as well as create habitat for other animals and kinds of vegetation. And I’m told that beaver dams can mitigate devastating drought.

An objective, fair-minded analysis would conclude that as “ecosystem engineers,” beavers rearrange ecosystems for their own benefit and, in the process, also affect humans, others animals and vegetation in ways both good and bad.

People a whole lot smarter and more knowledgable than me say that the changes, on balance, are positive. I won’t argue with them. But I respectfully suggest that folks who gush about “nature’s engineers” recognize that beavers destroy as well as create. For me — a guy who likes trees, especially oaks, and cattle — the destruction is a heavy price to pay for the upside.

What’s your take — scientific, agricultural or personal — on beavers and their impact on the environment?

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