A survey of invertebrates associated with wood debris in aquatic habitats

A field survey was undertaken to examine the community ofinvertebrates associated with wood debris in freshwater systems,with an emphasis on forested streams of the western states. Fifty-six taxa representing 5 orders of insects and other invertebratesare identified as closely associated with wood, while 129 taxa arelisted as facultative users. The methods of utilization range fromthe opportunistic use of the wood surface for refuge, resting andfeeding, to ingestion of wood tissue, including sub-surface bor-ing. Wood debris is found most abundantly in headwater streams,where the low streamflows cause less abrasion and displacementof the material, and allow more extensive conditioning by decom-posers. Obligate xylophages occurred predominantly in these loworder streams.