Habitat Dynamics of Beaver Castor canadensis at Two Spatial Scales

Terho Hyvönen ； Petri Nummi

《Wildlife Biology》 14卷3期 (2008/09) Pp. 302-308

並列摘要

We studied habitat dynamics of the Canadian beaver Castor canadensis in a boreal forest landscape in southern Finland at two scales: the beaver pond level and the landscape level. To explore the changes in tree species composition due to beaver browsing and flooding, six abandoned beaver ponds were sampled (537 sample plots altogether). For habitat dynamics at the landscape scale, the variation in the flooded area and the number of active beaver colonies were recorded during 18 years (1980-1998). At the pond level, flooding appeared to effect more rapid and more pronounced changes in woody growth production than browsing. Coniferous trees were particularly susceptible to flooding, and deciduous trees were more susceptible to browsing. Deciduous trees dominated during succession following a flooding. At the landscape level, mean occupation time of a colony site was found to be short (2.6 years), and the mean area of beaver impoundments was small (0.14% of the total area). Recolonisation of habitats occurred on average nine years after previous abandonment. A reason for the short occupation time may have been scarcity of food. The results suggest that both browsing and flooding should be considered when studying the dynamics of woody growth used by beavers.

並列關鍵字

beaver ； boreal forest ； Castor canadensis ； disturbance dynamics ； landscape ecology