How Beavers Can Help Rivers Withstand Wildfires and Climate Change
This article is based on insights shared during our fifth Alumni Webinar Series presentation, Beavers as Climate Allies: Restoring Rivers in the Greater Yellowstone Ecosystem, featuring Kurt Colhoff, Senior Climate and Water Conservation Associate at the Greater Yellowstone Coalition (GYC).
Many of us have probably seen a beaver dam, at least in pictures. These fascinating animals are known for their ability to reshape rivers, and are pretty adorable too. But their dams do more than change the landscape. They can also play an important role in helping rivers withstand the growing impacts of wildfires and climate change.
“By protecting and restoring beavers to their historical habitat, we can protect our rivers from the accelerating impacts of a changing climate,” Kurt explains.
Kurt specializes in fluvial geomorphology, the study of the physical processes that shape rivers and other aquatic systems over time. At GYC, he works on river restoration projects and advocates for improvements in policies and management to help ecosystems adapt to an uncertain future shaped by climate change and development.
So, what do beavers have to do with all of this? As Kurt explains, they are what scientists call a keystone species, meaning their presence has a particularly significant influence on the ecosystems they inhabit. Beavers create and maintain wetland habitats, which can retain surface water during severe droughts and support species like frogs and fish.
But Kurt’s presentation focused on another important part of their role: how beavers influence wildfire impacts, landscape evolution, and habitat creation and maintenance across larger areas. To understand this, we first need to look at two key concepts: riverscapes and beads.
Kurt emphasizes the importance of looking beyond the river stream itself and considering the entire riverscape. This includes the river, its floodplain (the surrounding land that can flood periodically), and the underground environment connected to the river. This broader perspective recognizes how water, nutrients, sediment, and other materials move throughout an interconnected system.
Beads are wide, gently sloping sections of a riverscape that can act as natural buffers against wildfire impacts. After a fire, large amounts of water, sediment, and wood can move rapidly into streams, potentially damaging aquatic habitats. Bead reaches help slow the flow, spread water across floodplains, and capture these materials, reducing erosion and protecting habitats downstream.
Wildfires have always been part of natural ecosystems, but climate change is altering fire patterns and, in many places, increasing the frequency and intensity of fires. As a result, rivers may have less time to recover between disturbances.
Naturally occurring beads can form through geological processes, such as glacial activity or landslides, but these features can take thousands of years to develop. That is where beavers play a particularly important role: they are among the most effective biological agents at creating and maintaining bead reaches.
Beavers build dams that retain water and sediment, often creating a series of dams along a stream. After a wildfire, these structures can capture sediment rapidly. Their effects can also last for years after beavers abandon a site or die, continuing to influence how water and sediment move through the landscape.
Unfortunately, beaver populations have declined dramatically, largely because of human activity. During the 19th century, estimates of North America's beaver population ranged from roughly 60 million to 500 million. By the time of their historical low, that number had fallen to around 100,000, largely due to hunting and trapping. As beavers disappeared, so did much of their influence on the landscape.
At the same time, human activities increasingly altered riverscapes. Water was diverted, river channels were straightened, and vegetation along waterways was removed or grazed down. Together, these changes simplified river systems and disconnected them from their floodplains. Instead of functioning like complex sponges that capture water and materials after a wildfire, many became more like channels moving sediment downstream.
Today, GYC and other organizations are working to restore these important river features. One approach is Low-Tech Process-Based Restoration (LTPBR), which includes building Beaver Dam Analogs (BDAs). These structures, made from materials such as wooden posts and branches, mimic natural beaver dams and help slow water and retain sediment. However, they are not a substitute for beavers themselves and may require ongoing maintenance.
For Kurt, the ideal outcome is for the “masters” to return. Beavers may take over existing restoration structures, maintain them, or build their own dams, helping restore and sustain these important river features over time.
Bringing beavers back, however, involves more than relocating them to places where they are needed. Montana, for example, has been piloting programs to move beavers to suitable areas where their ecological benefits are needed, including from places where they might otherwise be killed. But successful coexistence also requires policies and practices that allow beavers to thrive and remain on the landscape.
Beavers can sometimes create challenges for people, particularly when their dams affect bridges or private property. Rather than removing them, nonlethal approaches can help protect infrastructure while allowing beavers to continue their ecological work.
As Kurt explains, “We as a society can achieve a lot in this changing climate if we can get better at working with beavers, giving them the space they need to do what they do best.”
Of course, we cannot leave everything to beavers. Protecting rivers and preparing ecosystems for a changing climate also requires addressing other pressures, including deforestation, the loss of functional floodplains, and greenhouse gas emissions. But beavers can be valuable allies in these efforts, helping restore the natural processes that make rivers and the ecosystems around them more resilient.
Watch the full webinar:
