How Beavers Helped to Build America
Once abundant and widespread, beavers helped to forge the ground under our feet, making water safe to drink and the land an oasis for life. 
Yesterday’s update from the Discovery News blog was as good as we’re likely to see in this year or the next. It reviews the newly published research by some folks at Colorado State who have been using Ground Penetrating Radar to identify the effects of beaver dams on the substrata for the last 4300 years.
For the study, Wohl and colleagues Natalie Kramer and Dennis Harry used both ground-penetrating radar and near-surface seismic refraction to detect beaver-induced sedimentation.
My my my. The article is written by Jennifer Viegas who has been a benignly distant observer of the Martinez Beaver story for years. (I guess at one time we were fairly difficult to ignore).
The study determined that beavers contributed 30-50 percent of post-glacial sediments in the target area. “I think it very likely that our results are not unique to the Beaver Meadows study site, but also apply to other regions with relatively low rates of sediment yield to valley bottoms,” Wohl said.
She explained that beaver dams interrupt the flow of a stream, creating a backwater effect of reduced velocity. Sediment deposits in the backwater zone of the beaver pond, with this material remaining “in storage” until river erosion may mobilize it and carry it downstream.
The process is beneficial to humans, she continued, because “wet meadows associated with beaver dams have higher habitat and species diversity for plants, insects and other invertebrates, amphibians, reptiles, birds and mammals — pretty much all forms of life.”
Can I get an Amen? Astute readers of this blog will already know immediately where my mind headed the moment I read this article: If historic beaver dams can be identified from above ground in Colorado why not in the Sierras? Why not use GPR to prove what we’ve been struggling to document with painstaking ethnographic & archival research?
(Odd aside. I stumbled into GPR during the great sheetpile panic of 2008 when I was unsuccessfully imploring the city council they didn’t need to stick steel plates through the beavers’ living room. I suggested that they use GPR to find those alleged “tunnels” and make sure there was actually any problem in the first place. I even raised a few eyebrows when I suggested that they take a lesson from family court and if the study FOUND holes the city could pay for the radar, and if there WERE NO HOLES the property owner could pay. Of course you all know how that worked out.)
Never mind. This is an EXCELLENT article. Go read the whole thing. My very favorite paragraph comes at the end, and it kept me grinning for much of the day.
Due to intense beaver hunting, habitat destruction, pollution and other problems, the beaver population has plummeted by the millions in recent decades. Since beavers can impact human activities, their presence in areas remains controversial. Conservation groups such as Worth a Dam in Martinez, California, however, work hard to maintain beaver dams through responsible stewardship and to educate the public about the many benefits associated with beavers.
Thank you Jennifer for dropping our name at the end of such a bountiful list of beaver beatitudes! And thank you University of Colorado for showing us the beaver foundation beneath our feet! Next time you hear folks talking about our “Founding Fathers”, spare a thought for those Founding Beavers who laid rich soil across the united states, shaped our waterways and were trapped and made into hats as a thank you.
Maybe we can do better?
