Beaver dams a model for river restorers
River restorers can learn a lesson from the beaver that will produce a more natural ecosystem and save money, U.S. researchers say. Taking out old man-made mill dams on rivers and streams is a popular practice in New England and certain other states, said Melinda Daniels, an associate professor of geography at the Kansas State University in Manhattan, Ka.
Let’s be honest, there is really only one part of this story that’s surprising. We all know that beaver dams have enormous restorative effects on streams, and we all know that they’re a model of environmental responsibility. The only part that comes as a shock is that there’s a place in Kansas called “Manhattan“. Who knew?
Denise Burchsted from the University of Connecticut was lead author — with two other researchers and Daniels — of The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested Headwaters. The article appeared in a recent issue of BioScience, the journal of the American Institute of Biological Science
“The River Discontinuum” is the finest phrase I have ever encountered. Here’s a link to the paper. The title seems to wink from existence like something from a Wrinkle in time. I sense that Denise very much would like to find beaver friends across the country, and will write her immediately. In the meanwhile go read the comments on the CBC page. The mood about beavers is changing in Canada. If we aren’t very careful they’re going to get the answer long before we do.
Billions of dollars are being spent in the United States to restore rivers to a desired, yet often unknown, reference condition. In lieu of a known reference, practitioners typically assume the paradigm of a connected watercourse. Geological and ecological processes, however, create patchy and discontinuous fluvial systems. One of these processes, dam building by North American beavers (Castor canadensis), generated discontinuities throughout precolonial river systems of northern North America. Under modern conditions, beaver dams create dynamic sequences of ponds and wet meadows among free-flowing segments. One beaver impoundment alone can exceed 1000 meters along the river, flood the valley laterally, and fundamentally alter biogeochemical cycles and ecological structures. In this article, we use hierarchical patch dynamics to investigate beaver-mediated discontinuity across spatial and temporal scales. We then use this conceptual model to generate testable hypotheses addressing channel geomorphology, natural flow regime, water quality, and biota, given the importance of these factors in river restoration.
Abstract: The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested HeadwatersDenise Burchsted, Melinda Daniels, Robert Thorson and Jason Vokoun
