Over the past several centuries, the population of North American beaver has been dramatically reduced through trapping and habitat loss from an increasing pressure on streams and floodplains through human activity. The geomorphic impacts long-term beaver occupancy and activity can have on fluvial systems has also been lost, both from the landscape and from our collective memory such that physical and biological models of floodplain system function neither consider nor have the capacity to incorporate the role beaver can play in structuring the dynamics of streams. The resulting dramatic simplification of physical and biological stream processes places numerous species of stream rearing fishes in peril, as indicated most notably by the ESA listing of trout and salmon populations across the entirety of the Western US. The rehabilitation of stream systems is seen as one of the primary means by which population and ecosystem recovery can be achieved, and given the role beaver play in structuring stream habitat, managing the population dynamics of beavers or mimicking the geomorphic effects of beaver dams, could be a powerful tool to manage stream habitat rehabilitation.
Results/Conclusions
In a watershed-scale experiment, we have demonstrated that beaver dam analogs (BDA) have been successful in restoring an incised stream network in the Columbia Plateau of central Oregon (Bridge Creek in the lower John Day River basin). One of the most important take home messages from implementing this large scale experiment over the last decade is that ecosystems can be manipulated: fish and habitat changes are detectable and attributable to the restoration actions. While the primary focus of the watershed restoration experiment was effects on ESA listed salmonids, we also documented effects on riparian extent, ground water and surface water storage and temperature. However, what isn’t immediately apparent is how learning from this experiment can be shared and applied across the region. Through a set of simulation models using riparian condition, beaver restoration potential, geomorphic potential and confinement metrics available along stream networks, we now leverage our mechanistic understanding of fish and beaver population dynamics and the landscape hydro-geomorphic impacts to demonstrate the potential benefits of beaver based restoration across the interior Columbia River basin.