Captive beavers in a trial project run by Devon Wildlife Trust have been reducing the flow of soil and nutrients from intensively managed fields upstream.
Scientists at the University of Exeter studied the levels of sediment and the concentrations of phosphorus and nitrogen in each of the ponds created by the dams.
The 13 dams were built by the family of beavers at a secret location in west Devon since 2011, and have trapped more than 100 tonnes of sediment, 70 per cent of which was soil.
“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,” says Professor Richard Brazier, who led the research. “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.”
Soil erosion is a major worry for both the agricultural and conservation sectors, with the total cost of soil loss estimated to be £45 million (from the UK’s agricultural land).
The trapped sediment also contained high concentrations of nitrogen and phosphorus.
The leaching of nutrients into water courses can create problems for wildlife, and must also be removed from water supplies before it can pass drinking-quality standards.
“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,” says Peter Burgess, director of conservation and development at the Devon Wildlife Trust.
“It is truly inspiring to have our observations confirmed by detailed scientific investigations.”
Main image: Phelps the hedgehog undergoing hydrotherapy. © Devon Wildlife Trust