The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested Headwaters

Billiois of dollars are being spent in the United States to restore rivers to a desired yet often unknown reference condition In lieu of a known reference, practitioners typically assume the paradigm of a connected watercourse Geological and ecological processes, however, create patchy and discontinuous fluvial systems One of these processes, dam building by North American beavers (Castor canadensis), generated discontinuities throughout precolonial river systems of northern North America Under modern conditions beaver dams create dynamic sequences of ponds and wet meadows among free-flowing segments One beaver Impoundment alone can exceed 1000 meters along the river, flood the valley laterally, and fundamentally alter biogeochemical cycles and ecological structures In this article we use hierarchical patch dynamics to investigate beaver-mediated discontinuity across spatial and temporal scales We then use this conceptual model to generate testable hypotheses addressing channel geomorphology natural flow regime water quality and biota given the importance of these factors in river restoration