河狸水坝：锁住碳的天然“黑洞”？
Beavers are known for building dams, but a new study shows they might also be unexpected heroes in the fight against climate change. An international research team, led by the University of Birmingham, studied a stream in northern Switzerland where beavers have been active for over ten years. The scientists found that wetlands shaped by beavers store carbon up to ten times faster than similar areas without beaver dams. Over 13 years, the site captured about 1,194 tonnes of carbon. That equals 10.1 tonnes of carbon dioxide per hectare each year.
This process happens mainly because beaver dams slow down moving water. As the water calms, fine materials — known as sediments (沉淀物) — sink to the bottom. Dead plants and pieces of wood also settle. Over time, layers of these materials build up, trapping carbon deep underground. The research showed that such sediments can hold up to 14 times more inorganic (无机的) carbon and eight times more organic carbon than nearby forest soils. Nearly half of the long‑stored carbon came from deadwood in riverside forests.
The team also measured greenhouse gases like methane (CH₄). Methane release was very low, contributing less than 0.1 % of the total carbon budget. This means the wetland remains a net carbon sink. Although dry summers can cause some carbon dioxide to escape, the wetland stores far more carbon than it releases over a full year.
Dr Joshua Larsen, the lead senior author of the study, said that beavers do not simply change the landscape — they transform the way carbon dioxide moves through it. By expanding wetlands, they turn ordinary streams into powerful carbon sinks.