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WATERSHED RESTORATION spawning gravels) are equivalent or superior to nat- ural processes and structure; • A presumption that inchannel structures can miti- gate for riparian and aquatic degradation caused by land use practices (e.g., installing stntctures while allowing continued overgrazing, logging, or agricul- tural or industrial practices); and • Current paradigms of land stewardship (e.g., a lack of a social or political land ethic that implicitly rec- ognizes the value of natural or noncommodity prod- ucts associated with naturally functioning and intact riparian ecosystems). The rationale behind these reasons forms a common man- agerial paradigm: Stream, riparian, and fish habitat degra- dation brought about by anthropogenic activities, both local- ly and throughout a watershed, can be remedied solely through inchannel habitat manipulations. We suggest that the philosophy that natural habitat structure can be "im- proved" by engineering approaches misinterprets ecosys- tem needs and is an inadequate solution for fish habitat restoration. These approaches incltide activities that attempt to enhance fisheries habitat by eliminating natural barriers to fish passage, placing structures in intact ecosystems (old- growth forests), and putting spawning gravels or stntctur- al feaueres such as logs or boulders in reaches where they would not naturally exist. Such activities not only carry a high risk of biological failure, but also risk a loss of capital resources, labor resources, and public credibility. Sustainable and successful ecological restoration of degraded riparian systems is most likely to be achieved by considering the potential influences of proposed activities. Prior to the implementation of instream or riparian manip- ulations, the following questions should be addressed: • Has passive restoration (e.g., changes in grazing, log- ging, etc.) been implemented, monitored, and evalu- ated prior to choosing stntctural manipulations? • [Vill manipulations ultimately provide shade and thermally moderate stream temperature? • bVill they ultimately provide allocthonous inputs similar to that of stream-side vegetation? • 6Vi11 they ultimately provide the range of microhabi- tats typical of a particular stream? • GV"i!i activities facilitate restoration of riparian ye~eta- tion tl;at «-i11 restore natural channel morphology (e.~., oyerhan~ing banks, ~~idtiZ-to-depth ratios, pool/riffle morphology)? • Will they decrease time-rate dissipation of a stream's potential energy (i.e., stream power) by pro- viding increased flo«- resistance from stream-side vegeta- tion along a reach as compared with ener- w dissipation at localized points associ- ated kith inchannel structures? ~? == Fisheries • 4Vi11 they allow for increased channel sinuosity from increased hydraulic roughness (as would occur with recovery of riparian vegetation)? • -Will biogeochemical and nutrient cycling influences on water chemistry-the results of the unique functional linkages between hydrologic and biotic features of intact riparian zones-be preserved or restored? • Will the activities improve woody-debris recruitment and, hence, channel diversity because of enhanced vegetation establishment and growth? • Are the restoration activities composed of naturally occurring materials? Are their characteristics and functions within the natural context of the riparian and stream reach to be treated? Conclusions Riparian zones are rich ecosystems in terms of biologi- cal diversitj; unique biogeochemical processes, and pro- ductivity. For humans, riparian and stream ecosystems are a foci of commodity, recreational, and aesthetic values. The preservation and maintenance of intact riparian ecosys- tems and the restoration of degraded ones are important to local, regional, and global societies as well as to future generations. While we recognize that ecological restoration some- times comes at a high cost, we also note that ecological restoration is an investment in the natttral capital of stream and aquatic systems and, hence, the environmen- tal vv~ealth of the nation. Healthy riparian ecosystems are a subsidy of nature. Conversely, degradation is the squandering of this natural wealth through the deple- tion of the productive capacity of ecosystems. Clearly, restoring once-productive riparian and aquatic ecosystems in the western United States is in the best long-term em~i- ronmental and economic interests of the nation. Restored riparian and aquatic systems essentially will be self- maintaining and, therefore, useful in perpetuity (Cairns 1993). Because these ecosystems are a fundamental com- ponent of our life-support s~-stem, restoration should represent an important prioriri• for both public and p;i- yate lando~~-ners. Complex ecosystems and associated habitat features cannot be created via simple and artificial constr~:ction o` selected components. Ecological restoration is a holistic approach not achieved through isolated manipulations o individual elements but through approaches ensuring that natural ecological processes occur (National Research Council 1992). If society is to ttse, enjoy, and benefit from the wide range of val- ues and products associat- e ed with western riparian and stream ecosystems, concerted efforts of ecologi- cal restoration should begin before their productive po- tential, diversity, and beau- ty are forever lost. )~ Acknowledgments ri r; , We ~ti tsh to'~thank all of the biologists hydrologists, landowners;`aitc~ others"dedicated to fhe resfor'ation of the riparian and sfr~ em ecosystems of the ti~orld.-Much of l ,e research that generated:the`hypotheses and ideas prese_nt- ed in this paper~was fiinded by the U.S D r1.~:Pacific"' .Northwest Researcli"Stahori=Land and Water Interactions Team. ~Ve esperta~[ly ~ian~c peter Bisson;Nick Gerhardt; -and G©rdon Reeves for:tlieir helpfi:l reviews p€'this paper. Special Issue or~ L'a~e-shed Ras«~r~.;o,.