Beavers may help store carbon in rivers and wetlands.

A Swiss study found that beaver-built wetlands at one stream sequestered about 108–146 tons of carbon per year and estimated that similar wetlands across suitable floodplains could offset roughly 1.2–1.8% of Switzerland’s annual emissions.

Researchers in Switzerland studied a half-mile stream influenced by introduced Eurasian beavers. They measured carbon in water, the atmosphere, sediments, plant material and deadwood to calculate a carbon budget. The study, published in Communications Earth and Environment, found the beaver-built wetland acted as a net annual carbon sink. The site was estimated to sequester 108 to 146 tons (98 to 133 metric tons) of carbon per year. Key findings: - The wetland at the studied site sequestered an estimated 108–146 tons of carbon per year. - Scientists used sediment cores, plant samples and water-flow measurements to account for carbon stored and lost via water and the atmosphere. - The authors estimated that beaver-created wetlands across suitable Swiss floodplains could offset about 1.2–1.8% of the country’s annual emissions. - Researchers noted this result comes from one site and that carbon storage can vary with climate, geology, vegetation and available space. - Independent experts highlighted that wetter beaver wetlands can also make river landscapes more resistant to wildfire-driven carbon losses. Summary: The study suggests beaver-created wetlands can store measurable amounts of carbon at the landscape scale and could contribute modestly to national carbon budgets where habitat is suitable. Authors caution that broader estimates are uncertain because storage varies by location and more sites are needed to confirm results. Undetermined at this time.