Beavers offer lessons on managing water in a changing climate, whether the challenge is drought or flooding
By Christine E. Hatch, professor of earth sciences at UMass Amherst.Originally Posted in dialogue
Neither is accidental MIT and Caltech Claim Beaver (canadian castor) as their mascot. Famous engineers, beavers appear to be able to dam any stream, using logs and dirt to build structures that can flood large areas.
As climate change causes extreme storms in some regions and severe droughts in others, scientists find small-scale natural intervention by beavers Very valuable. In dry areas, beaver ponds can restore soil moisture; in wet areas, their dams and ponds can help slow flooding.These ecological services are so useful that land managers are shifting beavers In the United States and UK Help restore ecosystems and make them more resilient to climate change.
Scientists estimate that billions of beavers A waterway that was once dammed in the northern hemisphere.they are Hunted for its fur and nearly extinct In the 18th and 19th centuries in Europe and North America, but Comeback today in many fields.as a geoscientists specializing in water resources, I think understanding beavers in right place And find ways for humans to coexist with them in developed regions.
Scientists are studying how beavers could be used to mitigate wildfire and drought risks in the western U.S.
How beavers are changing the landscape
beaver dam stream forming pond, where they can build dome-shaped huts in the water to keep predators away. When they create a pond, many other effects follow.
Newly flooded trees die, but remain like bare “barriers” where birds nest. The diverted streams form intricately intertwined, slow-flowing waterways, tangled with logs and plants that provide hiding places for fish. The messy complexity behind beaver dams creates many different kinds of habitats for creatures like fish, birds, frogs, and insects.
human dam often blocked fishway Upstream and downstream, even dams Including fish ladder. but research shows The fish had no trouble migrating upstream past the beaver dam. One reason may be that fish can rest in slow pools and cool pond groups after navigating the highest part of the dam.
The slow-flowing water behind beaver dams is very effective at trapping sediment, which falls to the bottom of the pond.Study measuring total organic carbon in active and abandoned beaver meadows shows active and abandoned beaver ponds in North America before the 1800s store a lot of carbon in the sediment trapped behind them.The discovery is significant today as scientists search for ways to Increase carbon storage in forests and other natural ecosystems.
If the beavers are not threatened by bears, cougars or humans, they may survive in one place for decades, but if their ponds run out of food near their ponds, they will move on. When the abandoned beaver dam collapsed, the ponds drained and gradually turned into grass as plants on the surrounding land seeded them.
Dried grasslands can serve as floodplains for nearby rivers, allowing water to overflow and provide feed and spawning areas for fish during periods of high flow.Floodplain meadows are precious habitat For ground-nesting birds and other river-dependent species.
The value of slowing down the flow
As human settlements expand, people often want to use every acre of land. This usually means they want land that is firm and dry enough to farm, or waterways that they can navigate by boat. To create these conditions, humans removed floating logs from streams and installed gutters to pump water from fields and roads as quickly and efficiently as possible.
But covering more and more surfaces, such as sidewalks and roofs, with non-absorbent barriers means water flows faster into rivers and streams. Rainfall from common storms produces intense river flow, Erosion of banks and beds. With climate change Fueled stronger storms in many places, it magnifies this damaging effect.
Some developers use based on natural engineering principles, such as “water storage” to intercept it and slow it down; spread outflow more widely to slow the water down; and design depressions or depressions that allow water to sink into the ground. Beaver wetlands do all these things, only better.UK research shows that beaver activity can Reduce flood flow on farmland by up to 30%.
When a dam is damaged or washed away, beavers usually do repair work within 48 hours ?? pic.twitter.com/rxi7FMpmIc
— Beaver Trust (@BeaverTrust) September 30, 2021
beaver meadows and wetlands also Help cool the ground around and below themThe moist soils in these areas contain a lot of organic matter from buried and decaying plants, and they hold water longer than soils formed from rocks and minerals alone.in my wetland research, I’ve found that after a storm, water that goes into the ground travels through pure ore within hours to days, but can stay for up to a month in soils with 80%-90% organic matter.
Cool, moist soil also acts as a buffer against wildfires.Vegetation in beaver dam river corridors found in recent studies in the western United States more refractory Compared to areas without beavers, it does not burn easily because it is well watered and lush.Therefore, the area near beaver dams provides Temporary shelter for wild animals When The surrounding area burns.
make room for beavers
The ecological services provided by beavers are most valuable in areas where no one cares about landscape change. But in the densely developed eastern United States where I work, it’s hard to find open areas where beaver ponds can be deployed without flooding ditches or roads.Beavers also knock down expensive landscaped trees and feed on some cultivated crops such as corn and soybeans.
Beavers are often blamed for flooding in developed areas, although The real problem is often road design, not beaver dams. In this case, removing the beaver does not solve the problem.
Culvert Guard, fences, and other exclusions can keep beavers a safe distance from infrastructure and keep pond heights at a level that will not flood adjacent areas.Road intersections across streams aim to Let fish and other aquatic animals pass rather than block them Beaver friendly and resistant to climate change and extreme precipitation events. If these structures are large enough to allow debris to pass through, the beavers build dams upstream, which can help catch floodwaters.
A growing body of research shows that setting aside a small plot of land for beavers benefits wetland ecosystems, biodiversity and rivers. I believe we can learn from beavers’ water management skills, coexisting with them in our landscapes, and incorporating their natural engineering to respond to weather and precipitation patterns disrupted by climate change.