Beavers may be making the effects of climate change worse

Published: December 21, 2017

Beaver gnawing on a fallen log Photo courtesy of talesfromthewilds.blogspot.ca

Beavers may be beloved by Canadians, but scientists have found they are causing further harm to northern areas that are being affected by climate change.

When asked to explain the role beavers are playing in altering northern climates, Ken Tape, an assistant professor at the University of Alaska who studies beavers, likens it to gentrification.“Whether you want to call them ecosystem engineers or keystone species, beavers have a huge impact on the landscape,” Tape told the New York Times.

So how exactly are beavers affecting northern climates? First and foremost, by moving in. As northern temperatures have been warming and Arctic ice has been receding, beavers have been expanding their territories and moving into formerly perma-frozen regions. But because beavers build dams, they aren’t just living in the northern regions, but altering their structure and functioning. While dams are advantageous in some habitats, where they regulate droughts and flooding, in the north, they create new water channels that further thaw the permafrost.

Beaver by water and snow
Beaver dams can be advantageous in some regions, but the flooding they cause erodes soil and permafrost in the north. Photo courtesy of Jim Peaco/NPS

“When you start flooding areas with permafrost you immediately trigger permafrost degradation,” Tape said. “You start thawing the frozen ground that’s holding the soil together, and that water and soil and other things are washed away.”

Of course, to blame beavers for environmental destruction would shift responsibility from those who have done the most to cause it — humans. Still, their effect on the areas they’ve moved into is evident, as has been shown by satellite imagery since the ’50s. Satellite images of the same northern region show that it a transformation over 60 years from typical frozen northern tundra to a thawing landscape with streams and wetland. Tape and his colleagues made guesses about where they believed beavers had built dams which had amplified the effect, and they found them in 90% of the possible locations.

Satellite images of Arctic permafrost thawing from 1950 to 2012
These satellite images were taken in 1950, 1985, 2002, and 2012. The arrows point to beaver dam locations. Photo courtesy of EROS and Digital Globe/Ben Jones/USGS

Researchers have not proven that climate change is the only reason beavers are moving north (one theory says they’re returning to areas they were driven out of by fur traders in the 17 and 1800s), but their movement does echo a planet-wide trend of plants and animals moving north as those regions become warmer. And beavers affect the landscapes they move into more than most.

“Beavers are these agents of disturbance that come from outside of the ecosystem and impose their construction, their activities on this landscape,” said Dr. Tape. “Probably the best analog for beavers in the Arctic are mankind.”

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