Beavers and environmental flow : the contribution of beaver dams to flood and drought prevention

Sammanfattning: Before they were driven to near extinction, beavers populated the smaller rivers in Europe, Asia and North America. They are ecosystem engineers, since their dam building activities have a cascading effect on biogeochemistry, hydrology, ecosystem structure as well as biodiversity of the affected and surrounding area. I studied using a GIS (geographic information system) software whether dams built by beavers play a role in preventing drought in their surrounding area, and preventing flood downstream from their location. In the analyses, I combined identified beaver systems and digital elevation models to quantify the carrying capacity of beaver ponds. The Råne River catchment in northern Sweden was the study area. The mean area of the beaver ponds that were identified in the Råne River catchment are 3080 m² with a standard error of 241 m², with a total of 313 identified dams resulting in a total surface area of beaver ponds of 964124 m².