The Ecology and Management of Wood in World Rivers

Dynamics and Ecological Functions of Wood in Estuarine and Coastal Marine Ecosystems

Charles A. Simenstad, Alicia Wick, Stan Van de Wetering, and Daniel L. Bottom


Abstract.—The abundance, quality, and ecological fate of wood in estuarine and coastal ecosystems result from watershed and, ultimately, landscape-scale processes. Estuaries and coasts receive the wood exported from watersheds, in which fluvial import, retention, processing, and export mostly determine how much wood is available. The dynamics of wood in estuaries and coasts reflect somewhat different processes and rates than in rivers, however. Bidirectional and fluctuating fluvial-tidal flows, multiple sources, and retentive mechanisms generate complex patterns of wood movement through tidal ecosystems. Too often, wood is assumed to perform the same functions in estuaries as in rivers. With a few exceptions— such as wood acting as a disturbance in the rocky intertidal zone—these assumed similarities have not been demonstrated empirically. The dynamics and role of wood need to be examined across the continuum of watershed, estuarine, and marine ecosystems, with the coastal ocean serving as both sinks and sources of wood. Wood’s function in juvenile salmonid habitat is a prime example of extrapolating the role of wood in river ecosystems, often without substantiation, to estuaries and oceans. Large wood is often designed into estuarine wetland restoration projects at significant cost without any real evidence of its importance to fish in tidal environments. The use of wood by juvenile salmonids may be scale-dependent, and it may vary with factors that affect availability of refugia and predation rates, such as tidal elevations, river flow, and diel changes in light intensity. Tides and wind can produce heterogeneous distributions of wood, which may help support the tidal and seasonal movements of juvenile salmon. Management and restoration plans should protect upstream wood sources and delivery processes to maintain and retain the supply of wood to estuaries and coasts. Research on large wood is still needed to evaluate its habitat functions in coastal and estuarine ecosystems to develop criteria for assessing and restoring habitat and to understand variation in the role of large wood across estuary-ocean landscapes.