Recovery Plan for the Northern Spotted Owl - DRAFT

provide habitat for the numerous species associated with older forests. It isunlikely that a planted and even-aged, managed stand ever could simulate anold-growth system. However, habitat for many species can be provided in amanaged environment; therefore, conservation efforts for many organismsassociated with older forests, including the northern spotted owl, shouldinclude a combination of reserves and managed forests. Reserves wouldprovide true old-growth environments for those species with very narrowecological tolerance, and management practices for managed forests could beadapted to maintain populations of less specialized species that commonly areassociated with older forests.Northern Spotted Owl as an Indicator SpeciesConcern for northern spotted owls and debate over management of theirhabitat has been a persistent issue in Pacific Northwest forestry for two decades(USDA 1988, Thomas et al. 1990). However, spotted owls rarely havebeen the sole focus of this debate. Most frequently they have been used as asymbol of general concerns about the fate of old forests in the Pacific Northwest.The Forest Service recognized this general concern by designatingnorthern spotted owls as a management indicator species (MIS) in the ForestPlanning process (USDA 1984). Management for owls and other MIS wasadvanced as a way to adequately provide for the needs of several hundredother species associated with older forests (USDA 1988).Biological indicators have been used successfully as gauges of environmentalconditions in some situations (Thomas 1972). However, the use of vertebratespecies as indicators for other vertebrates has proven unsuccessful in severalstudies (Mannan et al. 1984, Szaro 1986), and the concept has been questioned.The attempted uses of vertebrate indicators, and reasons for failure ofthe vertebrate indicator concept, were summarized by Landres et al. (1988).Vertebrates have been used as indicators of population trends and of habitatquality for other species. Their use as indicators of population trends for otherspecies is likely to fail because each species responds to a different complex ofhabitat and climatic factors and is affected by interactions with other species.Mechanisms of population regulation also differ among species, making it evenless likely that one could indicate the population trends of another. The use ofvertebrates as indicators for habitat quality for other species is equally problematic.The factors that influence habitat quality are similar to those thatinfluence population density. The probability is small that one species adequatelycan represent those factors for a number of other species.Given the likelihood that no vertebrate can adequately represent a wholecommunity of organisms, what are the potential hazards of establishing amanagement strategy based solely on habitat needs of spotted owls? First, at alandscape scale, the locations of conservation areas established to meet theneeds of owls may not adequately provide for other species that have restrictedranges within the range of the spotted owl. Examples of this concern includethe marbled murrelet, which occurs primarily in the coastal forests, and someamphibian and mollusc species that have extremely small ranges (see sectionsbelow). These species could be missed entirely by a system of reserves establishedfor owls. Second, the spacing of conservation areas for owls may notaccommodate movement of species that have much more limited dispersalcapabilities. Amphibians, small mammals, and most invertebrates havelimited ability to move among large established areas that are long distancesapart. Finally, at the stand level, the specific habitat conditions that aremaintained for owls may not provide habitat for other species. For example,336