Recovery Plan for the Northern Spotted Owl - DRAFT

forests questionable. Experimental manipulations of habitat and assessmentsof prey response (as well as owl response) are needed to test the effectiveness ofmanagement techniques. Failure of habitat models to predict animal responsein locations and years other than the ones from which the data originally werecollected is a common problem (Noon 1986). This probably results from thenumerous factors besides habitat that affect animal populations (Noon 1986).The ability to manipulate habitat to increase prey availability is difficult becauseof the complex interaction of predator and prey.Ecology of Riparian Ecosystems and Native FishesThe committee's list includes approximately 132 species of animals that arefederally listed as threatened or endangered, candidates for federal listing,species of special concern, or older-forest associates and are associated withriparian areas. This list of species is diverse and includes three birds, fourmammals, 12 amphibians, 45 molluscs, and 34 arthropods as well as 28 fish.Riparian associates comprise approximately one third of the other speciesconsidered as a result of Secretary of the Interior Lujan's request. The associationto riparian areas by these species indicates the importance of riparianareas in the recovery plan for the spotted owl.Riparian ecosystems represent a small proportion of the land base (generallyless than 5 percent), but they provide habitat for a rich and diverse group ofplants and animals. A large number of fish stocks has been identified as beingat risk (Nehlsen et al. 1991, Moyle et al. 1989, Williams et al. 1989), in partbecause of intensive timber harvest along streams in many areas (see sectionon Native Fishes). The importance of riparian ecosystems, their roles inconiferous forests, and their potential importance as ecological corridorsamong DCAs is discussed next.Riparian EcosystemsRecently ecologists and land managers have recognized the importance ofstructure and function of riparian zones for terrestrial and aquatic ecosystems(Gregory et al. 1988, Knight and Bottorf 1984, Meehan et al. 1977, Beschta1989). These functions include stream shading, bank stabilization, nutrientuptake, input of leaves and needles into streams, sediment filtering, bankbuilding, and the contribution of large wood (Elmore and Beschta 1987,Gregory et al. 1988). The contrast in communities and physical environmentcreates rich patterns of processes and structure that are the basis for the highbiotic diversity found in riparian zones (Gregory et al. 1988).Management.-The segregation of riparian areas from other ecosystems bystate and federal agencies is a common management approach. The resultpredominately has been the development of federal policies and state forestpractices that allow varying intensities of forest activities. The states of California,Washington, and Oregon have addressed riparian ecosystems in theirforest practices rules. The states also are involved in an extensive monitoringprogram to evaluate the effectiveness of these rules.In general, federal agencies are consistent in their approach to the classificationof streams. Streams are segregated into four classes based on the presenceor absence of fishes, the uses of the water (e.g., domestic use by cities,recreation), and whether the stream is a significant contributor to a higherclassstream. The states use predominately the same process but have delineatedtheir streams by consolidating the categories into as few as two or asmany as four classes. Timber harvest regulations, however, vary among states369