Wetland Vegetation Dynamics in Response to Beaver (Castor canadensis) Activity at Multiple Scales

Abstract: Beaver activity is often considered a hydrologic disturbance that “resets” succession. We determined how beaver impoundment and wetland size and water chemistry affected the vegetation and succession of 25 beaver meadows and ponds using the space-for-time substitution. We used aerial photography to investigate whether a large 1947 fire in one region of Mount Desert Island, Maine, led to differences in regional temporal fluctuations in beaver pond occupancy over 60 y and determined whether these fluctuations led to different regional distributions of beaver wetland plant community types. Cluster analysis segregated 4 wetland groups: sedge meadows, sedge fens, shrub fens, and forested fens, which segregated along gradients of time since dam collapse, water chemistry, and wetland size. Beaver did not affect water chemistry or wetland size. Pond vegetation was a function of community type prior to flooding, water chemistry, and geomorphic setting. The successional model consisted of 2 separate cycle...