Large wood decay state and piece shape in river corridors

Abstract

Downed wood in river corridors displays diverse states of decay and piece shapes. Decaying wood provides habitat and nutrients for diverse organisms as well as subsidies to floodplain soils. We characterized the decay and piece shape categories of downed large wood in channels and floodplains of seven river corridors in Colorado, Montana, North Carolina, and Utah, USA, to evaluate how proportions of wood in these categories varied with respect to location (channel, floodplain), disturbance history with respect to recent overbank flows capable of transporting large wood, wood recruitment (fluvial transport, tree fall), and biome. We hypothesized that decay state and piece shape would differ more between floodplain and channel locations in river corridors with no recent inundation-related large wood transport on the floodplain than in river corridors with recent floodplain inundation. Results support our hypothesis with respect to decay but not piece shape. Decay state differs more between floodplain and channel locations in river corridors with no recent disturbance. These results have implications for efforts to retain and reintroduce decayed wood in floodplains.