Ecological Functions and Management of Large Wood in Fluvial Systems

Purpose of Review: The aim of this review is to provide an overview of the functional role of large wood in the functioning of fluvial ecosystems, ranging from the scale of microhabitats to entire catchments. To this purpose, this review is structured according to the major ecosystem processes occurring at different spatial scales, ranging from the microhabitat scale, e.g. the internal processes of organic matter breakdown by microbes, to the catchment scale, e.g. the catchment-scale-processes of water flow, sediment transport, and nutrient fluxes. Recent Findings: Recent research increasingly shows that dead wood drives a complex of multi-scaled processes. The role of large wood as a channel structuring entity and a driver of hydromorphological functioning is well known, but the importance of large wood at higher spatial scales has not been fully acknowledged. This encompasses the importance of large wood in enhancing multiple channel — floodplain interactions by creating a dynamic exchange of matter (water, sediments, nutrients) and energy. It also strengthens the water retention and storage capacity of rivers, attenuating floods and droughts and plays an important role in sediment, nutrient and organic matter interception, and processing. All these attributes contribute to ecosystem complexity and functioning, as well as providing valuable ecosystem services. Furthermore, large wood also acts as an important dispersal vector which, together with the multiple scale processes, promotes biodiversity. Summary: Recognising the multiple scale spatial and temporal processes acting in, around, and induced by large wood can strongly support future fluvial management, especially regarding the re-introduction and way of installing of large wood in rivers. As large wood management is context-dependent, research should focus on catchment specific processes.