Relationship Between Beavers and Wildfires (Credit: AGU EOS)

DISCUSSION: In order for a fire to occur, it requires fuel, oxygen, and some ignition source.  Moisture is a key determinant in the flammability of fuel, especially trees, branches, etc.  Hence, even in the midst of a drought, keeping at least a small section of the forest well-watered may help protect that section of forest from a wildfire.
 
Beavers tend to live in forests and use nearby materials (e.g., rocks, sticks, etc.) to build dams in streams or rivers.  This provides an area of calm water which is advantageous for them.  They also dig channels that extend away from their calm pools of water which may serve as irrigation channels for the nearby forest.
 
A study recently conducted out of California State University Channel Islands looked at a handful of fires that occurred where beavers live.  They used satellite data to assess differences in the health of vegetation before and after the fires.  They compared the differences adjacent to streams where the beavers lived and farther away from the impacts of the beavers.  Results of this study suggest that the vegetation near the beaver habitat was protected from the impacts of the fire, while the trees that were not irrigated by the beavers were more likely to be burned.  The irrigation from the beavers’ construction allowed the trees nearby to stay too moist to burn.  The video above produced by Emily Fairfax, the principal investigator on the study, illustrates how the process works.  Basically, beavers may be inadvertently helping to mitigate the impacts of wildfires.
 
Irrigating vegetation near waterways may have other benefits in addition to just protecting that vegetation from a wildfire.  Without irrigation, fires often burn right up to the edge of a river or stream.  This allows additional runoff of sediment and contaminants into the waterway during precipitation after the fire which can impact water quality, navigation, and flooding.  However, if vegetation near a waterway is protected during a fire (via beaver [or human] irrigation), this relatively healthy vegetation near the waterway after a fire may help reduce the flow of sediment and contaminants into that waterway.  In summary, beavers may be important for many reasons including helping to protect vegetation and waterways from the impacts of wildfires.
 
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©2020 Meteorologist Dr. Ken Leppert II