The floodplain wood budget: Linking wood dynamics and ecogeomorphic processes

Abstract Und erstanding floodplain wood transport, deposition and storage is necessary to fully close wood budgets in river corridors (the channel, floodplain and hyporheic zone). However, most work on wood in river corridors has focussed on in‐channel wood. Here, we review current understanding of wood dynamics in floodplains using a floodplain wood budget to highlight the processes that change floodplain wood storage. We discuss autochthonous and hillslope recruitment to the floodplain, floodplain wood decay and burial/exhumation, controls on lateral wood fluxes between the floodplain and the channel, and fluvial wood transport within the floodplain itself. We compile wood load data for floodplains and channels in locations in which data on floodplain wood loads exist, finding that floodplains are an important storage location for wood within the river corridor across diverse environments. We briefly review the impacts of floodplain wood on physical and ecological processes and then summarise important knowledge gaps that limit understanding of floodplain wood dynamics. We emphasise that future research should address methods to determine wood piece source location and track wood within the river corridor; mechanistically explore coupled flow‐sediment‐vegetation‐wood processes across spatial and temporal scales; extend observations of floodplain wood loads and storage characteristics and explore multiple size classes of organic matter; and work to inform management decisions related to floodplain wood. Because it may be less likely to be transported downstream and interact with infrastructure, floodplain wood may be less hazardous than in‐channel wood but can still provide ecological benefits and enhance physical complexity. Improving our understanding of wood dynamics on floodplains is thus important for supporting river management.