Characteristics of downed wood across headwater riparian ecotones: integrating the stream with the riparian area

Abstract

Although downed wood is a significant structural component of riparian ecotones, most studies of downed wood dynamics are conducted only within the stream bankfull channel or on the riparian forest floor. We examined downed wood structural characteristics (e.g., length, volume, and decay class) across the entire riparian ecotone of seven headwater streams in mature deciduous forests of northeastern Ohio to understand the structural relationships between downed wood and riparian ecotones. Sampling was stratified by hydrogeomorphic zones that were defined by lateral position within the riparian ecotone and correspond to differing fluvial geomorphology. Most downed wood pieces sampled were small (<1 m) and with a high decay class. Downed wood pieces within the baseflow zone (within the wetted channel) were smaller and more abundant than those within the transitional zone (within the bankfull channel excluding the wetted channel). Surface contact was inversely related to aquatic influence across the riparian ecotone, with downed wood in Zone 3 (riparian area beyond the bankfull channel) having significantly higher contact than wood within the other zones. The ecotonal approach and the incorporation of hydrogeomorphic influences is an alternative approach that moves beyond traditional approaches to more holistic management of riparian forests.