Beavers Building Dams Transform Tundra Stream by Making Warm Lakes that Melt Ice in Seward Peninsula, Alaska

Beavers built dams and created warm lakes that melted the ice, changing the tundra stream in the Seward Peninsula over time.

A few intrepid pioneers trudged across the tundra decades ago to start it all.

According to legend, one beaver traveled such a distance to get there that he scraped the skin off of the underside of its long, flat tail. Beavers are now more numerous than ever, with homes and colonies dotting the tundra in Alaska and Canada.

The far north has seen the arrival of beavers.

Although it's unclear what these newcomers will mean for the ecosystem of the Arctic, scientists and locals are keeping a close eye on the situation because their concerns are growing.

Researchers have found that the changes brought about by a warming climate are accelerated by the dam's beavers construct. Indigenous people are concerned that the dams may endanger the migration patterns of fish species on which they depend.

Beavers and Their Dams

Thomas Jung, a senior wildlife biologist for the Yukon government in Canada, said that beavers significantly modify ecosystems.

Their capacity for transforming the environment may be second only to that of humans because before fur trappers nearly wiped out the beaver population, millions of beavers shaped the course of the waters in North America.

Beaver dams have an impact on a variety of factors in temperate regions, including the height of the water table and the types of trees and shrubs that can be found there.

Because beavers depend on woody plants for nutrition and building materials for their dams and lodges, the northern limit of their range was previously defined by the boreal forest.

However, the Arctic is rapidly warming, making the tundra more habitable for large rodents.

An increase in shrubby plants like alder and willow, which are essential to beavers, has been brought on by earlier snowmelt, thawing permafrost, and a longer growing season.

Warm Water that Melts Ice

Aerial photos from the 1950s revealed that Arctic Alaska had no beaver dams or ponds at all.

Ken Tape, the University of Alaska's ecologist, recently conducted a study in which he combed through satellite images of virtually every stream, river, and lake in the Alaskan tundra and discovered 11,377 beaver ponds.

Because all of these new dams have the potential to alter much more than just stream flow, further growth might be unavoidable.

According to Tape, beaver dams produce warm regions since the water in the ponds they build is deeper and doesn't completely freeze over during the winter.

Even though the Arctic will change due to global warming whether there are beavers or not, the fragile far-northern ecosystems are particularly vulnerable to the types of disturbances that beavers may cause.

In fact, according to a paleobotanist from Trinity College Dublin, Jennifer McElwain, who wrote an article about plants' responses to historical warming episodes for the Annual Review of Plant Biology, the tundra may be the ecosystem on the planet that is most in danger from climate change.

Read also: New Analysis on Food Webs Helps Predict Ecosystem Responses to Invasive Species, Predators, and Climate Change 

Driven by Climate Change

In the midst of climate change, tape has tracked beavers as well as other animals that have migrated north onto the tundra, including moose that feed on tall, thick growths of shrubs that weren't present there 70 years ago.

However, beavers have a distinctive effect on the landscape.

Tape said that the best way to think of beavers is as disturbances, and wildfire, not moose, is their closest analog.

Scientists like Tape are only now starting to investigate what that disturbance means for fish as well as the people who depend on them in the Arctic.

In the 1980s and 1990s, Inupiat people living close to Kotzebue in northwest Alaska first observed beavers residing in nearby streams.

In 2008 and 2009, Inuvialuit hunters on the Yukon's north slope witnessed their first beaver dams.

Beavers can have a significant impact on the landscapes they live in, so it was alarming to see them in the vulnerable tundra ecosystem, Knowable Magazine reported.

The study by Tape and his colleagues is published in the journal Environmental Research Letters.

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