Beavers’ activities can create oases and limit spread of US wildfires

New research confirms suspicions that beaver activity can help stop forests burning.

A North American beaver drags small birch branch toward lodge in pond near Wonder Lake on autumn evening, Denali National Park, Alaska, USA. © Paul Souders/Getty

Climate change, arson and forest mismanagement have all been implicated in the devastating wildfires that have swept through swathes of North American wilderness in recent summers.

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But whatever the cause, a certain charismatic rodent may be at least part of the cure. New research demonstrates that, by damming watercourses, North American beavers create oases of wet forest that are spared from the flames.

Emily Fairfax of California State University was studying the impact of beavers on drought prevention when she stumbled upon a photograph of a wildfire in Idaho. “There was char all over the landscape, except around the beaver ponds, which were bright green,” she says. “That felt like enough of a nugget of evidence to study this more formally.”

To do that, Fairfax used satellite images to map the vegetation around beaver territories before, during and after a wildfire. This confirmed her suspicions that trees growing in the wetlands created by beavers when they dam a watercourse are often spared when an engulfing fire sweeps through the area. “If nothing else, the beavers are providing patches that other animals can hunker down in and stand a better chance of survival,” she says.

But in some circumstances, beaver activity might even be capable of stopping a fire in its tracks. “I think it’s possible where there are higher populations of beaver,” says Fairfax. “I looked at five large wildfires and only once did I see what I would consider to be a fire-break. That was an absolutely huge, kilometre-wide dam complex, and there wasn’t enough wind to kick the flames over to the other side.”

A beaver throws some twigs on top of his dam as his partner eats some grass near the shore, in Grand Teton National Park, Wyoming, USA. © Chase Dekker/Getty
A beaver throws some twigs on top of his dam as his partner eats some grass near the shore, in Grand Teton National Park, Wyoming, USA. © Chase Dekker/Getty

Fairfax says that beavers may be especially important now that so many wetlands have been drained and developed. “Historically, I don’t think these fires were scorching millions of acres without hitting a wet patch to slow them down, just because there was so much more wetland,” she says. “But today, beavers are one of the only things out there actively working to create and maintain these habitats.”

Read the full paper in Ecological Applications.


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Main image: A North American beaver drags small birch branch toward lodge in pond near Wonder Lake on autumn evening, Denali National Park, Alaska, USA. © Paul Souders/Getty