Consequences of Beaver, Castor canadensis, Flooding on a Small Shore Fen in Southwestern Quebec

Abstract

We describe the changes in a small peatland in Gatineau Park, Quebec, between 1878 and 2004. We correlate these changes with water levels and Beaver activity during this period. A shore fen persisted until 1980 under a regime of relatively stable water levels interspersed with episodes of somewhat higher water that killed encroaching trees. Significantly higher water levels in the early 1980s transformed the fen into a shallow water wetland containing a few partially-floating fragments of the fen. In 2003 a beaver dam collapse lowered the water level dramatically, exposing the peat surface and making it available for colonization by existing aquatic and shoreline communities. If maintaining the fen had been part of the Park’s beaver control program, water levels should have been allowed to fluctuate in order to control tree growth but not permitted to rise high enough or for long enough to drown the fen.