The geomorphic influences of burrowing beavers on streambanks, Bolin creek, North Carolina

Whereas the role of beaver darns and the resulting sedimentation processes are increasingly understood, little is known about the amount of sediment t ransported into a beaver pond as a result of other common beaver activities , such as burrowing and trampling. Volumetric measurements of beaver-induce d streambank erosion showed that beavers are important agents of landscape alteration along an 817 m stretch of Bolin Creek, North Carolina. Conspicuo us zoogeomorphic landforms were identified and analyzed, including 288 bank slides and 27 landforms that we termed "tunnel slides". Measurements yielde d a sediment loss of approximately 22 m(3) into the stream system over a 5 year period of beaver activity, resulting in an erosion rate of 0.054 m(3) per 10 meters of stream per year. Bankslide activity accounted for consider ably more soil loss than tunnel slides, ca. 20 m(3) and 2 m(3), respectivel y However, "tunnel slide" burrowing may have a greater geomorphic impact th an presently quantified. These burrows often disrupted tree root systems al ong the streambank edges, causing increased erosion due to tree tipping. So il loss was significantly greater along the west bank. An adjacent recreati onal trail along the east bank may function as a barrier limiting browse ac cess, resulting in less beaver activity.