Why wood should move in rivers

Abstract

Large wood is inherently mobile in naturally functioning river corridors, yet river management commonly introduces wood that is anchored to limit hazards. Wood that is periodically mobilized is important for: replacing stationary large wood that performs diverse physical and ecological functions; contributing to the disturbance regime of the river corridor; diversifying wood decay states; dispersing organisms and propagules; providing refugia during floodplain inundation and in mobile-bed channels; dissipating flow energy; and supplying wood to downstream environments including lakes, coastlines, the open ocean, and the deep sea. We briefly review what is known about large wood mobility in river corridors and suggest priorities for ongoing research and river management, including: structural designs that can pass mobile wood; enhancing piece diversity of introduced wood that is anchored in place; quantifying wood mobilization and transport characteristics in natural and managed river corridors; and enhancing documentation of the benefits of wood mobility.