BEAVER LANDFORMS

Abstract

This paper calls attention to the widespread zoo- geomorphic landforms arising from the activities of one of the most significant elements in the historical geography of Canada -the beaver, Castor canadensis. Although by 1900 extensive trapping for the fur trade had almost exterminated the beaver in North America (Naiman et al. 1988; Butler, 1991 b), changing fashions and conserva- tion since that time have allowed the beaver to re- establish throughout its historic range in Canada (Novak 1987). Beavers are essentially present throughout Canada south of the Arctic treeline, but at perhaps only one-tenth of their pre-European population levels (Novak 1987). Population density varies, with the greatest concentra- tions in boreal landscapes (Slough and Sadleir 1977); densfties there range from 0.4 to 0.8 colonies km-2, with an average of four to eight beavers per colony (Nairnan et al. 1988). In prairie environments density is lower, influ- enced by the limited food sources, agricultural land- uses, and large artificial dams (Bown 1988; Dieter and McCabe 1989a, b)