The Ecology and Management of Wood in World Rivers

Wood in Streams and Rivers in Developed Landscapes

Arturo Elosegi and Lucinda B. Johnson


Abstract.—Many catchments across the world have been highly modified by human activities, including agriculture, urban development, and other land uses, that often result in a complex landscape mosaic. We define developed catchments as those dominated by activities such as agriculture or urban development, irrespective of the extent and type of riparian zone present. Far fewer papers address large wood in rivers and streams within developed catchments compared with those in more natural situations, despite the fact that residential development and agricultural activities are so pervasive worldwide. The literature highlights a clear reduction of the abundance of large wood in agricultural and urban streams and rivers, although standing stocks are highly variable depending on local conditions. As a result of its scarcity, large wood seems to play a less important physical role than in forested ones. Nevertheless, large wood still plays an important role in developed streams and rivers by providing critical habitats for invertebrates and serving as the only retention structure remaining in some channels. A lower diversity of invertebrates and/or fishes and the loss of important functions, such as retention capacity, are reported for developed rivers, compared to those in forested regions. The geomorphic role of the wood remaining in these developed systems appears to be mixed— some studies report no such role, while others report an association of wood with pools. Gaps are evident in two areas: (1) many papers fail to adequately describe the landscape in which study streams and rivers are embedded, making it impossible to discern the dominant land use or, in some cases, even the nature and extent of the riparian vegetation; and (2) studies of ecosystem properties of streams and rivers in developed landscapes are rare. We suggest that more research should be undertaken in developed systems and that addressing the role of large wood is an important component of such studies.