Beavers Helpful Rebuilding Wetlands

Swamp Stomp

Volume 17, Issue 38

A new study researched in Scotland reveals beavers’ ability to engineer desolate land into thriving wetlands.

Four beavers were re-introduced to the land and observed for a decade. The observations found that the beavers created almost 200m of dams, 500m of canals and an acre of ponds. The landscape was “almost unrecognizable” from the original field, which now includes an increase plant species of almost 50% and richly varied habitats established across the 30 acre site.

The researchers say that their study is solid evidence that beavers can be a low-cost option in restoring wetlands, an important and biodiverse habitat that has lost two-thirds of its worldwide extent since 1900.

“Wetlands also serve to store water and improve its quality – they are the ‘kidneys of the landscape’,” said Professor Nigel Willby, at Stirling University and one of the study team. Earlier research by the team showed how beaver dams can slow water flows, reducing downstream flood risk and water pollution.

Beavers build dams in order to create pools in which they can shelter from their biggest predators, besides humans. These predators are bears, wolves and wolverines. The research was published in the journal Science of the Total Environment. The site was regularly surveyed and located near Blairgowrie in Tayside where two beavers were released in 2002 and began to breed in 2006. The lifespan of beavers is 10-15 years in the wild and the average number of beavers around during the study was four.

“After 12 years of habitat engineering by beaver, the study site was almost unrecognisable from its initial state,” the scientists concluded: “The reintroduction of such species may yet prove to be the missing ingredient in successful and sustainable long-term restoration of wetland landscapes.”

Alan Law, another member of the team from Stirling University, said: “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.”

He said wetland restoration usually involves ditch blocking and mowing or grazing to maintain diversity: “Beavers offer an innovative, more hands-off, solution to the problem of wetland loss. Seeing what beavers can do for our wetlands and countryside highlights the diverse landscape we have been missing for the last 400 years.”

The downside to using beavers to revitalize landscapes is that it has to be carefully managed to deal with the potential impacts on farmers, who fear crops being raided by beavers and damage to embankments that protect low-lying fields and other areas from floods.

“Any species introduction, particularly if it has not been in this country for hundreds of years, can have a massive impact on the many benefits that the countryside delivers,” said Mark Pope, chair of the National Farmers Union’s environment forum. “The impact of beavers is assessed across the whole landscape considering the impacts on all land uses. This study is just one piece of that big jigsaw. We need to learn from Scotland’s experiences before any decisions are taken on the future status of beavers.”

There is also concern about the impact of beaver dams on salmon and other fish. The fear is that beavers might block migration upstream. But Wilby said: “The main conclusions from recent studies were that the overall effect of beavers was positive.” This is because greater biodiversity provides more food for the fish and the deeper pools maintain stable cool water temperatures, even as the climate warms.

“I think as long as beavers have plenty of space to form a decent number of territories, there are enormous potential benefits,” said Wliby. “Sometimes the negative views of farmers can dominate.”

Source: Carrington, Damian. “Eager Beavers Experts at Recreating Wildlife-rich Wetlands, Study Reveals.” The Guardian. Guardian News and Media, 19 July 2017. Web. 19 July 2017.