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Beavers help reduce water pollution and soil erosion

Scientists at the University of Exeter are reporting that beavers can dramatically improve the quality of water in rivers while preventing the loss of valuable soils from surrounding farms and fields.

In collaboration with the Devon Wildlife Trust, the researchers conducted an experiment which revealed that enclosures constructed by beavers can reduce the input of soil and nutrients into water systems by the tons.

The study was focused on a single family of beavers, which have lived within a fenced site in West Devon since 2011. A total of 13 dams built by the beavers have slowed the flow of water and created a series of deep ponds.

The researchers found that the dams had trapped more than 100 tons of sediment, 70 percent of which was soil from grassland upstream. Further analysis revealed that the sediment contained high concentrations of nitrogen and phosphorus, which are nutrients that cause issues for wildlife found in rivers and streams.

Richard Brazier is a professor of Earth Surface Processes and the lead author of the study.

“It is of serious concern that we observe such high rates of soil loss from agricultural land, which are well in excess of soil formation rates,” said Professor Brazier.

“However, we are heartened to discover that beaver dams can go a long way to mitigate this soil loss and also trap pollutants which lead to the degradation of our water bodies.”

“Were beaver dams to be commonplace in the landscape we would no doubt see these effects delivering multiple benefits across whole ecosystems, as they do elsewhere around the world.”

Devon Wildlife Trust has also been conducting a second project that is focused on wild beavers in the River Otter. Peter Burgess is the Director of Conservation and Development at the wildlife charity.

“Our partnership with Exeter University working on both our fenced and unfenced beaver trials is revealing information which shows the critical role beavers can play, not only for wildlife, but the future sustainability of our land and water,” said Burgess. “It is truly inspiring to have our observations confirmed by detailed scientific investigations.”

The study is published in the journal Earth Processes and Landforms.

By Chrissy Sexton, Staff Writer
Image Credit: Michael Symes/Devon Wildlife Trust

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