Association of State Wetland Managers - Protecting the Nation's Wetlands.

The Wetland Wanderer: Can Climate Change Impacts be Reduced by Nature’s Wetland Restoration Expert?

by Brenda Zollitsch

For those working in development, planning, transportation and flood prevention most likely the image that comes to mind when you use the word “beaver” is of a large, furry, flat- tailed, tree-cutting, pond-producing foe.  While the impacts of a population of beaver in many places may be The American Beaver: "Castor canadensis"entirely unwanted, in specifically-identified areas of regions that need wetland restoration to counter drought and fire hazards, beavers may have an important role to play in restoring wetlands and climate adaptation.

A Short History Lesson:

Beavers are nature’s engineers and have been essential to shaping the complexity of natural drainage systems since long before our country was settled.  Beavers are habitat-modifying keystone species (McKinstry, Caffrey and Anderson, 2001).  Beaver activity creates systems of ponds, channels, wetlands, marshes and wide riparian zones (Floughty, 2008). However, beaver trapping in the late 1800’s led to a virtual eradication of beavers, resulting in what hydrologist Suzanne Fouty Wetlands created by beaver damscalls “the first large scale Euro-American alteration of watersheds” (ibid).  The resulting changes to drainage systems has been shown to  decrease system stability and complexity by lowering water tables, reducing summer base flows, increasing flooding frequency, reducing woodland acreage, increasing sensitivity to drought, and decreasing the amount of time that watersheds store and release water (ibid).  The absence of beavers limits nature’s ability to deal with climate change and extreme weather events (Fouty, 2008).  Beavers can also contribute to carbon sequestration through their wetland work, especially in bogs and fens (Mitch, 2009).

The Challenges of Beaver Reintroduction

When we start talking about beavers, it is a complicated issue.  Beavers and human development often don’t work well together. Trapezoidal Culvert Protective Fence Westford, MassachusettsBeavers construct dams that block culverts and wreak havoc with highway and other road work.  Beaver dams can flood extensive uplands, they cut down desirable trees, burrow into stream banks, and chew apart Styrofoam under docks.  People worry they have a beaver “infestation” as lodges seem to start popping up everywhere (even though one family of beavers may make several lodges).  Sadly, beavers are better known for the headaches they cause than their remarkable ability to rebuild and restore important aquatic resources.

Restoration Efforts Using Beavers:

Despite the challenges associated with beavers, a growing body of literature and practitioner reports indicates that beavers are one of the most effective and speediest contributors to wetland restoration.  Case studies show that when beavers are introduced in specially-selected areas where they were present in the past, their work can be remarkable.  While the National Academy of Sciences report that manmade wetlands are not effectively duplicating the functions of natural wetlands, beavers have the ability to turn land back to its natural state, including wetlands (Aschwanden, 2002).  Some important case studies can be found by researching the Methow Valley Beaver Reintroduction Project (a ten-year NOAA project), a reintroduction project on the Lower Santa Fe River (River Source) and in the Upper Mississippi River Basin (Hey and Phillipi).  These studies and others indicate a range of benefits from beaver reintroduction which address some of the critical needs associated with creating climate resiliency, especially in the arid western states.  Beaver reintroduction can increase stream complexity, riparian vegetation structure, species diversity, vegetative groundcover, floodplain connectivity, sediment transport and nutrient cycling as well as water quality, quantity and storage (Fouty, 2008).

Overcoming Barriers to Beaver Reintroduction:

When thinking about beaver reintroduction, one thing is very clear: Beavers are unpredictable.  They build where and when they want.  When they find a location they like, it is very hard to discourage them from wanting to rebuild their dams over and over again – when food becomes Installing a Flow Device in a Beaver Damscarce, they move on. Therefore, beaver reintroduction as a wetland restoration tool should be restricted to sites where placing beavers make sense.  Brown and Fouty (2011) point out that reintroduction requires proactive identification of appropriate beaver sites.  Especially desirable are sites on large tracts of public land, where there are few consequences for beaver movement, flooding and landscape change.  Such lands abound in a number of western states.

Additional considerations include the importance of preparing a site through restoration of woody vegetation prior to reintroduction (Brown and Fouty, 2011), restoration-friendly regulation of beaver trapping (Illinois Department of Environmental Regulation, 2014; Fouty 2008), and the use of specific tools to reduce unwanted beaver impacts.  Examples include:

  • Modern water control devices (Brown and Fouty, 2011);
  • Galvanized wire fencing (Brown and Fouty, 2011);
  • Targeted protection of tree stands (Illinois Department of Environmental Regulation, 2014);
  • Earthen dikes to discourage burrowing (Brown and Founty, 2011);
  • Identification of water depths that will keep both beavers and humans happy (Aschwanden, 2002); and
  • Identifying water levels that don’t trigger beaver dam-break alarms and building activities (Aschwanden, 2002).

To learn more about connections between beavers and wetland restoration, we encourage you to go to the following websites and/or organizations for more information:

References:

Aschwanden. (2002). Leave the wetlands to beavers: As beavers reclaim their rightful places in our environment, experts help us adjust to our industrious new neighbors. National Wildlife Federation.

Bird, O’Brien and Peterson. (2011). Beaver and climate change adaptation in North America: A simple, cost-effective strategy.  Wild Earth Guardians, Grand Canyon Trust and The Lands Council.

Brown and Fouty. (2011). Beaver wetlands.  Beaversprite. Spring.

Fouty, S. (2008). Climate change and beaver activity: How restoring nature’s engineers can alleviate problems. Lakeline: Spring.

McKinstry, Caffrey and Anderson. (2001). The importance of beaver to wetland habitats and waterfowl in Wymoming. Journal of the American Water Resources Association. 37(6)1571-1575.

Mitch. (2009). Beavers open savings accounts: Wetlands, especially peatlands, store carbon best.  Beaversprite: Spring.

Illinois Department of Natural Resources. (2014?). State’s beavers rebounded from near extinction: Illinois beavers contribute to wetlands and wildlife; often are tough customers for homeowners and farmers.  ORC Wildlife Virtual News.

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