You’ll remember that a while ago we talked about “The Medium”, the newish platform for reading tightly written articles that make you a whole bunch smarter about a subject you might not have even known about before. Two months ago they hosted a fantastic article about beavers and salmon by Megan Michel and I guess it did pretty well because here comes another by Rosie Struve. All I can say is GO BEAVERS!
Building a Better Beaver Dam
To understand the story of the beaver, it’s important to see the role that beavers play in a riparian ecosystem. Beavers maneuver deftly through water with their paddle-like tails, gnaw through wood with their sharp teeth, and fell entire trees across streams to build their habitats — beaver dams. Their hands are nimble and dextrous, enabling them to arrange rocks into a sturdy foundation, weave branches into dense wooded walls, and spread mud and silt like masons laying mortar. Through the construction of these dams, beavers are able to alter the surrounding environment more than almost any other mammal, aside from humans.
Like man-made dams, beaver dams fully or partially block the stream or river. This blockage slows the flow of water, creating nearby ponds and shallow wetlands. These wetlands are fertile ground for diverse vegetation, which serves as a perpetual food source for the beaver and other animals. Beaver dams also filter water and trap sediment, creating a protected and ideal environment for fish to lay their eggs. More than just a habitat for the beaver alone, beaver dams have positive impacts on the surrounding ecosystem, affecting everything from the water temperature to the biodiversity of flora and fauna in the area.
Nice summation Rosie, we’re right there with you.’
These man-made knock-offs are called Beaver Dam Analogues, or BDAs. BDAs are constructed by pounding wooden posts into a stream bed and weaving in smaller limbs and willow branches across the channel — a tidy and streamlined interpretation of the beaver’s craft. The goal is to imitate the complex environment of a beaver dam to reap the environmental benefits, to ultimately restore a more vibrant and biologically diverse ecosystem.
So far, the results have been encouraging. A 2019 report from a project in the Bridge Creek watershed in Eastern Oregon, conducted by the US Forest Service, found that BDAs resulted in more opportune water temperatures for fish, increasing the overall population of threatened Columbia River Steelhead. The water tables in the area were also raised, creating a larger floodplain and naturally irrigated meadows.
Yes but Rosie, that’s not because humans stepped in and took over the beaver job, it’s because humans allowed the beavers to do their job again and helped them be more successful.
Beavers may have once been the architects of the natural world, but that position has long been overtaken by humans. But just as we have innovated our way to the brink of a climate crisis, we are now faced with the challenge of innovating our world back to the state it was once in. The Oregon Office of Fish and Wildlife suggests that “beaver are being hailed as one of the most cost effective and sustainable solutions for ecological restoration and climate change resilience.” After centuries of inflicting human egotism on the landscape, we are finally looking to the creatures who have been mediating intertwined natural systems since long before we got here. BDAs are a small glimpse of hope that reverting back to that state may be possible.
