Patterns of Landscape Use by Beaver on the Lower Roanoke River Floodplain, North Carolina

Satellite imagery was used to map dramatic increases in area impounded by beaver activity between 1984 and 1993 in the Roanoke River floodplain of eastern North Carolina. The tenfold increase in beaver impoundment coincides with natural increases in beaver populations in North Carolina and the transfer of lands within the floodplain into conservation ownership. The results were analyzed within a geographic information system to examine patterns of landscape use by, and landscape changes resulting from, beaver activity. In general, floodplain beaver impoundments are associated either with sloughs, where ponds form connected linear complexes extending the length of a swale; or backswamps, where ponds spread unconstrained from the edge into the interior of the swamp. Increases in beaver activity between 1984 and 1993 dramatically increased the length of beaver-pond edge and associated habitat within the floodplain. Additionally, beaver ponds became significantly less isolated within the floodplain, making beavers a significant environmental influence upon vegetation dynamics within the floodplain. Although beavers do not specifically browse upon baldcypress (Taxodium distichum) and water tupelo (Nyssa aquatica), areas characterized by these species are most affected by increased beaver activity because these also represent the areas that are most prone to flooding. Localized beaver activity may result in decreased forest regeneration owing to the extended flooding caused by beaver impoundments and the growth of shrub-herbaceous “beaver meadows” along the saturated fringes of beaver impoundments. [Key words: beavers, bottomland hardwoods, floodplains, remote sensing, geographic information systems, Roanoke River.]