Beavers use sharp teeth to cut down trees and shrubs, build dams, submerge small valleys, and form new lakes that can cover several hectares of land.
These new bodies of water contribute to the melting of frozen permafrost, which is a huge reservoir of natural methane gas (an effective greenhouse gas).
In the past few years, scientists have discovered beavers on the tundra in Alaska. These beavers have never been seen before-according to research on high-resolution satellite images, these animals are building dams in their new communities. Published in “Environmental Research Newsletter” on Monday.
They also seem to be building dams and new lakes at locations most likely to increase the melting of the permafrost.
Ingmar Nitze, a researcher and author of the Alfred Wegener Institute at the Polar and Marine Research Center in Helmholtz, Potsdam, Germany, said: “We are seeing exponential growth there. These The number of structures approximately doubles every four years.”
“Their method is very effective.”
The study found that the number of beaver dams in the 100-square-kilometer area surrounding Kotzebue in northwest Alaska increased from two in 2002 to 98 in 2019, an increase of 5,000%. The larger 430-square-kilometer beaver dam on the Baldwin Peninsula in Alaska has increased from 94 in 2019 to 174 in 2013 and 409 last year.
Nietzsche said: “You can see them in the image and find them (dam). You can also see the development of the lake. They have unique signals.”
Blame it on the beaver?
Nietzsche said there are several different factors that explain why beavers occupy an area that is not usually called home. One is climate change, which is changing tundra that is usually free of trees.
He said: “We have seen an increase in vegetation. There are more bushes, so all beavers need to build dams or as food.” In addition, because of their thin winter ice, they used to freeze solids in the past ‘S lake now provides beavers with more friendly conditions.
Tundra is also not a common habitat for beavers, so they will not face predators or resource competition, and these animals are now better protected by US federal law, and humans hunt far fewer animals than before.
Because the lake formed by the beaver contains hotter water than the surrounding soil, the new body of water accelerates the melting of the permafrost.
Nietzsche said: “The role of permafrost is that water interacts very strongly with the frozen soil below.” “The more surface water, the worse the permafrost, because in winter, cold air cannot seep into the ground again, and the water will store a lot The heat can even seep into the ground,” he said.
The study found that in the past 17 years, lakes and water bodies affected by beavers accounted for two-thirds of the 8.3% increase in the total surface water area of the Kotzebue study area.
Beavers also seem to be aiming intuitively at the lost lake basin, and turbocharging has affected the landscape and permafrost they cause.
“This is a special landscape. There are usually many lakes, but they are dynamic, so they can drain and leave a lot of basins… and these beavers are smart enough to block the exit and refill the basins. They will block a lot It can be done with minimal effort.”
Nietzsche said the beaver dam construction boom may also occur in the Canadian tundra or Siberia.
“We are working hard to expand the scope of analysis.”
Nietzsche said: “There are a lot of people trying to quantify the emissions of methane and carbon dioxide in lakes in the Arctic, but they have not yet specified.
“This is a very new topic and something we have discovered in the past few years. Beavers will have a considerable impact on these landscapes, so there is no real quantitative method for these lakes, but it will be done in the future.”