A new study shows that beavers in northern Switzerland have turned a stream corridor into a major carbon sink, storing over 1,000 tonnes of carbon in just 13 years. Researchers found these wetlands capture carbon at rates up to ten times higher than similar areas without beavers. The findings highlight beavers' potential role in climate mitigation.
Researchers from the University of Birmingham, Wageningen University, the University of Bern, and international collaborators studied a stream corridor in northern Switzerland where beavers have been active for more than a decade. Published in Communications Earth & Environment, the study measured carbon dioxide (CO2) released and captured due to beaver activity, creating the most complete carbon budget for such a landscape in Europe yet. Over 13 years, the site accumulated 1,194 tonnes of carbon, equivalent to 10.1 tonnes of CO2 per hectare annually—up to ten times more than comparable areas without beavers. The wetland acted as a net carbon sink, storing an average of 98.3 ± 33.4 tonnes of carbon each year, mainly through subsurface retention of dissolved inorganic carbon. Sediments in these beaver-modified wetlands held up to 14 times more inorganic carbon and eight times more organic carbon than nearby forest soils, with deadwood from riparian forests accounting for nearly half of long-term storage. Methane emissions were minimal, less than 0.1% of the total carbon budget. During summer, when water levels dropped, the system briefly became a carbon source, but annual net storage prevailed due to sediment, plant matter, and deadwood buildup. These reserves can persist for decades if dams remain intact. Dr. Joshua Larsen from the University of Birmingham, lead senior author, stated: 'Our findings show that beavers don't just change landscapes: they fundamentally shift how CO2 moves through them. By slowing water, trapping sediments, and expanding wetlands, they turn streams into powerful carbon sinks.' Dr. Lukas Hallberg, corresponding author, added: 'Within just over a decade, the system we studied had already transformed into a long-term carbon sink, far exceeding what we would expect from an unmanaged stream corridor.' Dr. Annegret Larsen from Wageningen University noted: 'Our research shows that beavers are powerful agents of carbon capture and adsorption.' Scaling up, beaver recolonization in suitable Swiss floodplains could offset 1.2-1.8% of the country's annual carbon emissions without human intervention.