Emulating Riverine Landscape Controls of Beaver in Stream Restoration

Abstract

Stream and floodplain restoration at the reach scale has ranged from expensive, heavy‐handed modification of the channel and floodplain to simple, longer‐term revegetation efforts. We have developed and implemented a simple approach that emulates the ecosystem engineering effects of beaver. This approach is less expensive and disruptive than typical large‐scale engineering efforts and has the potential to restore both fish habitat and floodplain vegetation more rapidly than simply revegetating and waiting for the riparian zone to mature. The approach involves constructing log flow‐choke structures that mimic the hydraulic function of a natural beaver dam during flooding. By placing these structures throughout a naturally entrenched stream reach at locations promoting increased frequency of flood connection with floodplain swales and relict channels, we set the stage to restore the riparian corridor and floodplain more quickly than could be achieved through revegetation alone. Monitoring shows that within just one to two years of implementation, beaver are building more persistent dams in close proximity to our structures, and we are seeing increased hydraulic connectivity with the floodplain. Our technique may therefore provide a cost‐effective, natural process‐based restoration tool with potential large‐scale benefits.

Ecology, management, and conservation implications of North American beaver(Castor canadensis)in dryland streams

“…In a similar study from semi‐arid Idaho, DeVries et al . () documented increased frequency of overbank flows (i.e. hydrologic connectivity with the floodplain) around artificial structures constructed to imitate beaver dams.…”

“…Somewhat limited empirical evidence from temperate streams supports this hypothesis (reviewed in Pollock et al, 2003;Rosell et al, 2005), but few data are available from dryland streams. Where management goals include reducing erosion or sedimentation, promotion of beaver dams may be an effective strategy (DeVries et al, 2012). However, in many dryland river systems, large peak flows are important in conservation of native fish (Rinne and Miller, 2006) or plant (Stromberg, 2001) communities.…”

“…Beaver dams create lentic habitat, promote landscape heterogeneity, and alter stream hydrology, sediment dynamics, and nutrient cycling (Naiman et al, 1986), with numerous implications for flora and fauna (Rosell et al, 2005). There is an emerging interest in employing or mimicking this remarkable engineering power in stream management efforts (DeVries et al, 2012;Pollock et al, 2012), but beaver activity can also conflict with other ecological management goals or create significant economic damage (Nolet and Rosell, 1998). Discussions over whether and where to promote beaver populations (Longcore et al, 2007;Carrillo et al, 2009) are now at the forefront of the conservation debate, leading to new questions about the historical distribution, abundance, and ecological effects of beaver.…”

Impacts of beaver dams on channel hydraulics and substrate characteristics in a mountain stream

“…Previous research has shown the ability of beaver dams to have a significant impact on each of these areas. As a result, many restoration projects are beginning to use beaver and beaver dam structures as an ecological and cost‐effective approach in restoration and management (Andersen & Shafroth, ; Burchsted et al , ; Curran & Cannatelli, ; DeBano & Heede, ; DeVries et al , ; Pollock et al , ).…”

Beaver dams shift desert fish assemblages toward dominance by non‐native species (Verde River, Arizona, USA)

“…Recent decades have witnessed growing interest in employing or mimicking the remarkable engineering abilities of beaver (Castor canadensis and C. fiber) in stream restoration efforts (Pollock et al 2007;DeVries et al 2012). Recent decades have witnessed growing interest in employing or mimicking the remarkable engineering abilities of beaver (Castor canadensis and C. fiber) in stream restoration efforts (Pollock et al 2007;DeVries et al 2012).…”