Beaver Dams Flood Boreal Forests and Restore Dead Wood Sources, Researchers Say

It's no surprise that tress are especially valuable to wildlife – but even the dead parts of living trees and fallen logs act as vital food and shelter sources for several species. So when dead wood is removed from forests and used to create man-made products, animals suffer. A recent study from the University of Helsinki, Finland, revealed that deadwood has significantly declined in boreal forests, but beavers might have a solution to the dead wood problem.

Boreal forests are characterized by long winters and moderate to high annual precipitation. Mostly conifer trees grow in this area, though deciduous can also be found. Beavers essentially use the branches and logs of these trees to build large dams, which subsequently interfere with the natural flow of water systems and sometimes may even cause an area to flood. While flooding ultimately deprives trees of water which may kill them, the beavers are basically renewing deadwood sources, according to the university's news release.

For their study, researchers examined dead wood quantities and types scattered throughout areas in southern Finland. When compared to non-beaver sites, researchers found shore forests near beaver dams were much more abundant with dead wood. Additionally, beavers often relocate when they run out of wood to use, so they end up creating several dead wood hotspots in their wake. This ultimately benefits numerous species, including insects, salamanders, snakes, mice, and shrews that seek shelter from rotting logs, as well as skunks, bears, and woodpeckers that make a buffet out of the insects. 

"Beavers could be used to aid and uphold dead wood production in dead wood-poor lowland boreal forests. The species would concurrently facilitate the restoration and conservation of wetlands, which are one of the most endangered ecosystems in the world," Stella Thompson a doctoral student at the University of Helsinki, explained.  

The findings were recently published in the journal Forest Ecology and Management.

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