Description:
Beavers may provide some natural mitigation of the effects of climate change on the Columbia Wetlands by increasing wetland resilience and complexity, and specifically by increasing open water area. Most of the research undertaken on beavers has not been in a floodplain system the size of the Columbia Wetlands, where the river is large and undammed and the floodplain is up to 2 km across. Beavers in the Columbia Wetlands are not damming the Columbia River itself, they are damming small side channels and wetlands within the floodplain, and the impacts of this type of dam-building activity are very different from the impacts of dam-building activity in incised streams or even in river floodplains of around 500 m in width. Crucially, while in an incised stream system water flow is unidirectional, only flowing over the beaver dams one way, in a floodplain system the water flows over beaver dams in both directions. In the spring, as the flood pulse rises, water flows over the beaver dams from the Columbia River into the wetlands; once the flood pulse has receded, the water flows out of the wetlands (either over, through, or under the dams, if they are present) into the Columbia River. Thus, the influences of beaver dams on the morphology, hydrology, and vegetative characteristics of these wetlands are likely profound, and as yet not well understood.

Keywords: wetlands; beaver; hydrology; climate change

Authors:

Organization: Columbia Wetlands Stewardship Partners

Category: Hydrologically Vulnerable Wetlands

Focal Area: Columbia Wetlands

Resource Type: Report

Year: 2024