What might the reintroduction of beavers mean for the UK’s wild spaces?

TeaThe Eurasian beaver, once a common sight throughout Europe, had almost completely disappeared by the end of the 16th century, thanks to hunting and river modification for agriculture and engineering.

but beavers are making return back UK and many other countries. they have already been released into the wild Scotland and within enclosed river sections in England. now expanding wild release The number of beavers is on the cards across England.

Improving ecosystems, increasing biodiversity, flood protection and improving water quality are some of the benefits of having beavers. But reintroducing wild animals into the landscape is always going to involve trial and error, and it’s important to understand the potential consequences—both good and bad.

The beaver is a talented environmental engineer who has been able to create its own ecological niche by building dams – matching its environment perfectly. These dams are built from materials that beavers can tote Or float – usually wood, stone and clay, but also fence posts, crops from nearby fields, satellite dishes and old children’s toys.

The dam creates a peaceful, watery home for beaver families to sleep, eat, and escape from predators. And the effects of dam construction ripple outwards with the potential to transform entire ecosystems.

our review The study of beaver impacts considers evidence from across Europe and North America, where there have been wild beaver populations. Expansion of from around 1950.

Water

There is clear evidence that beaver dams increase water storage in river landscapes by raising groundwater levels, along with the creation of more ponds and wetlands. This could help rivers – and their inhabitants – handle more common weather extremes such as floods and droughts.

If you see beaver dams in the wild, the water often comes very close to the tops of their dams, suggesting that they may not be of much help in flooding. however, some studies It is finding that beaver dams can reduce flood peaks, possibly because they divert water toward floodplains and slow down the flow. However, we do not know whether beaver dams reliably reduce floods of various sizes, and it would be unwise to assume that they are always capable of protecting downstream structures.

the good news is that it seem All the additional water dam reserves can help supplement rivers during dry periods and act as important refuges for fish, amphibians, insects and birds during droughts.

Pollution

Beaver dams increase the time taken by rivers to carry things downstream. In some cases, this can help slow the spread of pollutants such as nitrates and phosphates, which are commonly used in fertilizers, which can harm fish and harm water quality.

The effect of beavers on phosphate is unclear, just that many studies have found phosphorus concentrations to increase downstream of beaver dams, with little or no change. But beavers seem to be particularly adept at removing nitrates: a welcome skill, as high concentrations of nitrates in drinking water can put infant health at risk.

recovery of diversity

The storage of water means that beavers form a wonderful mosaic of still, slow- and fast-moving water habitats. In particular, they increase the biodiversity of river basins, for example by helping macro-invertebrates such as insects and snails – keys to a healthy food chain – to thrive.

The departure of beavers can leave anything from fens or peatlands to wetting floodplain forests, which can dry out the grasslands that have developed in their wake. This gives it an important role in efforts to rejuvenate the beaver.

But the nuances are important here. For example, the evidence for the effects of beaver dams on fish populations and river valley vegetation is very mixed. because they are so great agent of disturbance, Beavers promote plants that germinate quickly, such as woody shrubs and grasses.

While this can reduce forest cover and help some invasive plants, given time it can also help create valleys with a rich mosaic of plant life. So although the presence of beavers is likely to benefit, more research is needed to be clear on how beavers change ecosystems.

net zero carbon

beavers are great trapping Carbon by storing organic matter such as plant detritus in slow-flowing ponds. However, this also means that beaver ponds can be sources of greenhouse gases, such as CO₂ and methane, that contribute to the greenhouse effect. This led one writer to wonder “whether beavers know the greenhouse effect will reduce demand for fur coats”.

Can beavers still be helpful in achieving net zero carbon? The short-term answer is probably yes, as more carbon appears to be trapped than is released by beaver activities.

However, the long-term consequences are less clear, because the amount of carbon beavers keep in the ground depends on how willing they are to roam the river valley – and how willing we are to let them. A clear understanding of where beavers fit within the carbon cycle river system needed if we are to make the best use of their carbon capture skills.

Management

Beavers are re-entering the landscape under human dominance, the same thing that originally drove them from vast areas of European river systems.

In the UK, this means they would lack natural predators and could compete with cows and sheep for food: possibly as a result of unstable wild population trajectories.

Although good data on long-term beaver activity is available from Sweden, Norway and Switzerland, our different climates and landscapes mean that direct comparisons are difficult.

The use of beavers in reconstruction can be incredibly cost-effective, as dam construction and the biodiversity gains from it are largely done for free. But we need to be tolerant of uncertainty about where and when they want to do their jobs.

Dealing with wild animals—which might not share our preferences—is always an unpredictable process. The expansion of beavers in the wild has a bright future, as long as we can manage the expectations of the people who own and use beaver-populated land.

Joshua Larsen is Senior Lecturer in Hydrology at the University of Birmingham. Annegret Larsson is an assistant professor of geography at Wageningen University. This article first appeared on Conversation.