RESTORATION OF STREAM HABITATS IN THE WESTERN UNITED-STATES - RESTORATION AS REEXPRESSION OF HABITAT CAPACITY

Ecological restoration is increasingly invoked as a tool for the maint enance and regeneration of biodiversity. Yet the conceptual foundation s and assumptions underlying many restoration management activities ar e frequently unclear or unstated. Unforeseen, undesirable consequences of restoration activities may emerge as a result. A general conceptua l framework for restoration is needed to better accommodate dynamic ha bitat systems and evolving biota in restoration strategies. A prelimin ary framework for stream habitat restoration emphasizing stream habita t-biota development is proposed, As developing systems, streams and st ream biota exhibit temporal behaviors that change with stream environm ents. Underlying the dynamic development of streams is potential capac ity. Streams express this capacity as an array of habitats over time a nd across the landscape. Human land uses in the western United States have rapidly altered aquatic habitats and the processes that shape hab itat. As a result, the diversity of native fishes and. their habitats has been suppressed. Restoration is fundamentally about allowing strea m systems to reexpress their capacities. Several steps are provided to guide stream restoration activities. Key tasks include: identificatio n of the historic patterns of habitat development; identification of d evelopmental constraints; relief of those constraints; classification of sensitive, critical, or refuge habitats; protection of the developm ental diversity that remains; and monitoring of biotic responses to ha bitat development.