Beavers are busy, fuzzy, and have big orange buck teeth. But what do they have to do with fire and drought in California? Turns out, a lot.
Beavers build dams and create wetland ecosystems that store water, keeping vegetation green and healthy. Further studies have found that these wet, well-connected habitats create pockets of fire-resistant landscape that do not burn, even in some of the most severe wildfires, providing robust refuges for beavers, birds, fish, frogs, bears, deer, and even humans during and after a fire.
Capitalizing on the ecosystem benefits associated with beavers has led to increased interest in restoring their populations in the state. In 2023, California established the Beaver Restoration Program, which aims to promote beaver-related restoration as a nature-based solution to climate change. To better understand this potential, a recent Ecological Applications study led by Jessie Moravek, PhD ’24 Environmental Science, Policy, and Management (ESPM), quantifies how much fire refuge and water storage beavers can create in 31 watersheds of California’s Sierra Nevada.
“As beaver restoration takes off in the state of California, it is important to understand where and how much the state’s ecosystems could benefit from beavers,” said Moravek, who led the study as a graduate student and is now a postdoctoral researcher in the lab of University of Minnesota Professor Emily Fairfax.
Using a model called the Beaver Restoration Assessment Tool (BRAT), which relies on vegetation and hydrology datasets to predict where beavers can build dams, Moravek and her collaborators modeled the potential for beavers to build dams in the Sierra Nevada region. This allowed them to estimate the size of fire-resistant areas beavers could create, and how much water their dams could store. They found that beavers in the Sierra Nevada have the potential to make approximately 2,200 square kilometers worth of fire refuge—roughly the size of 24,000 football fields—and to store nearly 120 million cubic meters of water, which could fill 48,000 Olympic swimming pools.
The team used these estimates to identify priority watersheds for beaver restoration. They focused on areas at high risk of fire and drought, and where beavers would likely build lots of dams. “Identifying priority watersheds for beaver restoration helps us understand where beavers can thrive, and where their engineering can best help people,” Moravek said.
Beaver restoration efforts do not always start with actual beavers, Moravek added. “One common strategy for mimicking the benefits of beavers is to build a man-made beaver dam, called a beaver dam analog, which can mimic the benefits of natural beaver dams,” she said. The study helps researchers and land managers identify where beavers could be successful, as well as the rivers and wetlands that could benefit from restoration actions that mimic beavers’ benefits. “But of course, the end goal is to always have beavers return to that ecosystem and do the wetland restoration, fire resilience, and water storage work for us,” she adds.
Additional co-authors include ESPM Professors Albert Ruhí, Justin Brashares, and Manuela Girotto; Shane Feirer and Robert Johnson from University of California Agricultural and Natural Resources; Randi Spivak from The Center for Biological Diversity; Andy Kerr from The Larch Company; Andrea Molod and Augusto Getirana from the NASA Goddard Space Flight Center; and Emily Fairfax from the University of Minnesota.
