Beavers: Heroes or villains of climate change?
Dr. Carol Johnston, Professor Emerita, South Dakota State University
Sponsored by Fund for Lake Michigan
The benefits of beaver ponds and meadows to wildlife are well known, but beaver-created wetlands also play an important role in the carbon cycle. Beavers submerge wood to create dams, lodges, and food caches, and that wood can take hundreds to thousands of years to decay. Beavers don’t work alone: their plant and microbial partners respectively increase carbon capture and decrease decomposition rates. Tussock- and mat-forming sedges are promoted by water fluctuations in beaver wetlands, providing the photosynthesis that sucks in atmospheric carbon and converts it to plant tissue. Organic detritus from these plants decomposes under anaerobic conditions, a much slower process than aerobic decomposition. Partially decomposed organic matter becomes incorporated into the soil, sequestering carbon in recalcitrant forms. Beaver dams at the outlets of peatlands raise water tables, enabling vertical accumulation of peat. There is a dark side of beaver wetland creation, though, because numerous studies have shown beaver ponds to be hotspots of methane flux, a potent greenhouse gas. So, are beavers heroes or villains when it comes to climate change?
Sponsored by Fund for Lake Michigan