Stream - Riparian Rapid Assessment

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In~licato~ Selection Four principles guided our selection of the specific variables that are included in the RSRA. First, we focused upon indicators that not only measured the ability of the system to provide specific functions, but that at the same time would reflect other important ecological processes within the stream-riparian system. For example, in the fish habitat section we consider the rela- tive amount of undercut banks along the reach. Undercut banks not only provide important habitat and cover for fish and other aquatic species, but their presence indicates that the bank itself is well vegetated, and that there is sufficient root mass to allow the development of the hour-glass shape channel cross-section typical of most healthy stream systems. This in turn would suggest that the fluvial processes of erosion and deposition along that stretch of the reach are in relative equilibrium. Second, we focused upon variables that could be measured rapidly in the field and that would not require specialized equipment or training. As a result, the protocol can be conducted not only by specialists, but also by conservationists, agency personnel, ranchers, and interested lay- people that have received some initial trainng. More detailed methods have been developed for many of the individual indicators included in this protocol. However, because they often require considerable time and expensive equipment, the use of such protocols will often limit the other binds of information that can be reasonably collected from the reach. Our goal was to obtain an overall picture of the fiulctioiung of the system under assessment within a two to three hour period. Should any of the individual components of the reach be found to be particularly prob- lematic or non-functional, the more specialized methods can then be used during later visits to collect additional quantitative information on that variable. Third, we measure only the current condition of the ecosystem, rather than creating scores that are based upon some hypothesized future state or successional trend. That is, we are concerned with the ability of the ecosystem to provide some important function at the present time, and not whether it would be likely to do so at some point in the future, if current trends or manage- ment practices continue. We used this approach because stream-riparian systems are highly dynamic and they are often subject to disturbances (e.g., large flooding) that will alter succes- sional trends and make predictions of future conditions highly problematic. In addition, by evaluating only current conditions, this protocol can be used as a powerful tool for monitoring and measuring future changes in the functional status of the system. For exam- ple, if a reach is rated as in poor condition with respect to a particular set of parameters, reeval- uating the system using the identical protocol in subsequent years gives one the ability to meas- ure the effectiveness of airy management change or active restoration program and to undertake corrections if the restoration actions are found to be not producing the desired changes. This type of adaptive management approach can be extremely difficult if the evaluation and monitor- ing measures are based primarily upon the expectations of some firture, rather than current, con- dition. Fourth, and for similar reasons, we use a quantitative approach to score variables and measure ecosystem health. Many current assessment systems that are based upon dichotomous 6