BEAVERS could be Scotland’s secret weapon to improving the ecosystem according to a new report, which proves they help restore wetlands and boost biodiversity.

Researchers from the University of Stirling studied the effects of a small group of beavers on a wetland in Tayside and found that local plant diversity rose by 46 percent and the total number of plant species doubled. Species which normally grow in areas with high nitrogen levels decreased, indicating a return to more natural soil conditions.

Between 2003 and 2015 the beavers – which either escaped or were originally released illegally in the area – constructed 195 metres of dams, 500 metres of canals and an acre of ponds, surrounded by supportive plant life and vegetation.

Wetlands, known as “the kidneys of the landscape”, are seen to have a hugely important role in protecting our environment, with coastal wetlands in particular considered to have an important role in fighting climate change.

Dr Nigel Willby, of Stirling University, said: “Wetlands are tremendously important environments for biodiversity. They also serve to store water and improve its quality. However, the world’s wetlands are disappearing at an alarming rate. The latest estimates suggest that almost two-thirds have been lost since 1900.

“Beavers are renowned for their engineering skills, like dam building, and are now being considered as tools for restoring wetlands.

“They have been reintroduced widely, including in Scotland, partly for this purpose and our findings demonstrate the surprisingly large benefits they can bring to biodiversity.”

The study, partly funded by Scottish Natural Heritage (SNH) and published in the international journal Science of the Total Environment, is said to be the first to fully measure these environmental benefits over time.

Beavers, which were hunted to extinction in Scotland about 400 years ago, were officially designated as a native British species north of the Border following a successful long-term pilot reintroduction project in Knapdale, Argyll overseen by the Scottish Wildlife Trust and the Royal Zoological Society of Scotland (RZSS).

However, while the three Knapdale beaver families were introduced with a government licence, others in Perth and Tay are thought to be have been introduced illegally.

Up to 250 beavers are estimated to be living in rivers and lochs over several hundred square miles in the catchments of the rivers Tay and Earn and dozens have been shot by landowners and farmers, concerned that beaver dam-making will lead to tree loss and flooding.

Study co-author Dr Alan Law said the study provided hard evidence of their uses. He added: “We know lots about the benefits of beavers in natural settings but until now we did not know the full extent of what they can achieve in present-day landscapes where restoration is most needed.”

Susan Davies, director of conservation for the Scottish Wildlife Trust agreed the study confirmed many of beavers’ known benefits.

She said: “Beavers are one of the world’s best natural engineers, with an impressive ability to create new wetlands.

“This new study reinforces the findings of the Scottish Beaver Trial, which demonstrated the wide range of benefits that beavers bring to local landscapes, and led to the Scottish Government’s decision to allow beavers to stay in Scotland.”

As well as increasing plant diversity, she claimed beavers benefit a wide range of species including dragonflies, water voles and otters.

“The dams and ponds created by beavers can also improve overall water quality by acting as sinks for pollutants, and trapping sediment,” she added. “As beavers naturally expand their range over time we’d expect these wide-ranging benefits to spread to lochs and rivers across Scotland.”

An SNH spokeswoman said it was working with partner organisations to help develop “a pragmatic and flexible” licence for beavers to be released in other parts of the country that both helped bring benefits and recognised the damage they could do to farmland. “This latest research will help us plan how beavers can be integrated within the Scottish countryside for the greatest benefit, balanced with any issues they might cause,” she added.