Beavers can teach researchers a thing or two about improving wildfire resistance（在线收听）

Beavers can teach researchers a thing or two about improving wildfire resistance

Transcript

After two large wildfires swept through areas of Colorado in 2020, there were spots largely spared thanks to beavers. (This story originally aired on ATC on Oct. 16, 2021.)

A MARTINEZ, HOST:

It can take years, decades even, for landscapes burned by wildfires to come back. The recovery has just begun in Colorado, where the state's two largest fires ever, in 2020, left behind more than 600 square miles of ashy soil and charred trees. But some places were largely spared, thanks to beavers. From member station KUNC, Alex Hager reports.

ALEX HAGER, BYLINE: Emily Fairfax and I are trudging across a field of knee-high grass. Here in the Poudre Canyon near Fort Collins, we're surrounded by scorched and charred hillsides from last year's fire. But underfoot, it's the kind of golden green meadow that swishes around your legs with each step.

EMILY FAIRFAX: So this is pretty active beaver landscape. You are in marshy terrain.

HAGER: And at a few points, there's no way around the water.

How secure is the footing on the other side?

FAIRFAX: Not (laughter) secure would be the correct assessment of that.

HAGER: We need to be extra careful because this swampy landscape has been sculpted by beavers. Fairfax is an ecohydrologist who studies the creatures, and she's navigating these narrow channels snaking through the wetland. And there are a ton of them.

FAIRFAX: There is at least about 10 ponds up here that are large enough to see in satellite images. And then between all those ponds is just an absolute spiderweb of canals, many of which are too small for me to see until I'm here on the ground.

HAGER: Beavers create these wetlands by damming up a stream. Then they build out a network of channels, keeping a lot more water in one place. That makes a little patch of land that's partially fire resistant. That's why right here we're in the middle of a lush, soggy meadow. But just a stone's throw away is the blackened edge of the Cameron Peak Fire.

FAIRFAX: When you're at this beaver complex, it never stops being green. And everything else in the landscape, the hillslopes on either side, they both charred. They lost all their vegetation during this fire. But this spot, it did not. These plants were here last year, and they're still here today.

HAGER: About a hundred feet past this spot, the burned trees still have some of their needles. Another hundred feet past that, they're just blackened toothpicks. It shows just how effectively the wet ground held back the fire. Beavers are crepuscular animals, meaning they're only active at dawn and dusk, so we didn't see any on this visit. But once it gets dark, they'll get back to work on this landscape, which also serves as a kind of reservoir in a place where there used to be more water and wetlands before they were shrunk by drought.

JOE WHEATON: It's mimicking this critical function that used to be pervasive in these riverscapes.

HAGER: Joe Wheaton studies the flow and formation of rivers at Utah State University.

WHEATON: And is a similar function to what snowpack does - of a inefficient movement of water that leads to healthier riverscapes.

HAGER: Just like snow, beaver wetlands hold water for gradual release, slowing it down on its way to the places where humans divert and collect it, and that's likely to get more important. Climate change means warmer temperatures and less snow, making high mountain water storage even more valuable. Ecohydrologist Emily Fairfax says humans have tried enhancing water storage by building mock beaver dams of their own. Ultimately, though, they're not as effective as the real thing.

FAIRFAX: The beaver complex in the beaver wetland is so much more than the dam. It's the channels. It's the digging. It's the chewing. It's the constantly, you know, changing the landscape, the dynamics, the flexibility.

HAGER: And in the middle of Colorado's largest wildfire ever, beaver dams kept hundreds of acres from burning. Fairfax says it'll take far more research before we can figure out just how effective they are when it comes to slowing down burns on a large scale. But for now, these areas and the beavers that call them home are surviving as oases of green in big fires all across the West.

For NPR News, I'm Alex Hager in Fort Collins, Colo.