table of contents Sierra Nevada Forest Plan Amendment Appendix R - Assessment of Species Vulnerability and Prioritization The scope and scale of conservation issues has increased as land management and conservation focus has evolved from single species to more integrative ecosystem perspectives. Bioregional assessments have become valuable tools for assessing the status and condition of large-scale ecosystems and have provided an opportunity to incorporate science into the land management policy arena (Johnson et al. 1998). However, uncertainty exists regarding what methods constitute the best approach to use for bioregional assessments (Franklin 1998). A fundamental goal of ecosystem management is to conserve or restore the full complement of species, as species are integral to the structure, composition, and functioning of ecosystems, and land management agencies must satisfy legal and regulatory requirements to ensure viable populations (e.g., National Forest Management Act, Endangered Species Act). Objective approaches are needed to prioritize species for conservation to focus management attention and limited funding on species in most need of conservation actions and to provide a basis for determining appropriate levels of monitoring that are commensurate with the conservation status of the species. A number of approaches have been proposed for assessing risk or the conservation status of species. These approaches range across a gradient from purely qualitative to point scoring systems to rigorous quantitative analyses that estimate extinction probabilities over time (e.g., Ahern et al. 1985, Millsap et al. 1990, Mace and Lande 1991, Akcakaya 1992, Molloy and Davis 1992, Given and Norton 1993, Mace 1994, Lunney et al. 1996, Mace and Kershaw 1997). Each of the approaches has associated strengths and weaknesses. One strength of qualitative assessments is that they have modest data requirements, although lack of explicit criteria for determining status can introduce inconsistencies into these schemes (Chalson and Kieth 1995, Todd and Burgman 1998). Point scoring systems are a considerable advance over qualitative assessments because they make explicit use of relevant ecological criteria in setting conservation priorities and are both transparent and repeatable. However, arbitrary weighting across numerous variables, lack of justification for consistent weighting of variables across taxa, and lack of independence among variables can result in an unreliable ranking of conservation priorities (Lunney et al. 1996, Todd and Burgman 1998). All of these methods also have a common flaw in that they ignore uncertainty in the data (Todd and Burgman 1998). Demographic models, either deterministic or stochastic and/or spatially explicit, can provide insight into population dynamics and their relation to landscape pattern and to predict extinction probabilities, in relative or absolute terms, over time and/or to compare different management strategies. However, these types of models are data hungry and model projections can be sensitive to uncertainty in parameters (Rucklehaus et al. 1997). Further, model projections also assume that future conditions remain similar to those that occurred when the data used to parameterize the models was collected. Thus, given differences in the potential strengths and weaknesses of each different approach, careful consideration needs to be directed at determining which approach is most appropriate for a given application based on; 1) the goals and objectives of the assessment; 2) the types and quality of data available; and 3) how the results of the assessment will be used for conservation planning, management, and monitoring. FEIS Volume 4, Appendix R-1 - Assessment of Species Vulnerability and Prioritization Sierra Nevada Forest Plan Amendment Vulnerability assessments were separately conducted for three taxa; Terrestrial Vertebrates (amphibians, reptiles, birds, and mammals), Fish, and Plants. The objective of the vulnerabilitity assessments was to identify those species that were at greatest risk to loss of viability within the Sierra Nevada Bioregion. Individual viability assessments were completed and presented in Chapter 3 for each of the species at risk that were identified through this process. Vulnerability assessments were conducted separately for each of the taxonomic groups because of basic differences in distribution and abundance patterns and in the current state of knowledge for each taxa, although certainly other groupings could have been used (e.g., combine fish with other vertebrates; combine amphibians with fish). Only those species that were known to occur within the Sierra Nevada planning area for this project were included in the vulnerability assessment. The Appendix is structured with a subsection for each taxa that describes the methods used and results of the vulnerability assessment for that particular taxon. Upon completion of the vulnerability analysis, a final screening process for Terrestrial Vertebrates and Fish was conducted to identify those species at greatest risk and would be subject to further analysis. This group included: • All federally listed Endangered, Threatened, Candidate and Proposed species. • All State of California Threatened and Endangered Species. • All U.S. Fish and Wildlife Service Species of Special Concern. • All U.S. Forest Service Sensitive Species. • All High Vulnerability Species. • All species identified in the Sierra Nevada Framework Notice of Intent. • Moderate vulnerability species meeting one the following combinations of conditions that, using principles of conservation biology (small population size or known population decline), were judged to place a species at risk to loss of viability: 1. Population size = 2 (1-100 individuals); 2. Population trend = 1 (know population decline), except when Population Size = 5 (> 10,000 individuals); 3. Or new information since the specialists’ rating indicated a valid viability concern (sage grouse, band-tailed pigeon). From this resulting group of species a preliminary evaluation was conducted to determine the type of analysis that would be conducted for each species. • Full viability analysis presented in Chapter 3; • Limited discussion presented for the species and presented in Appendix R for those species judged to be peripheral (known to occur within the Sierra Nevada Bioregion but not known from NFS lands), extirpated from NFS lands, transient, accidental or extremely peripheral to the extent that no know self-sustaining breeding populations occurred on NFS lands within the planning area; • Local endemic that only occurs on 1-2 forests within the Sierra Nevada planning area or peripheral on NFS lands but common on other lands within the Bioregion. A preliminary analysis was conducted for these species with the following possible outcomes: from a coarse filter analysis, features of one or more alternatives provided the ecological conditions to provide a high likelihood of maintaining viable populations (full treatment in Chapter 3); if no alternative provided the high likelihood – e.g. did not specifically address stressors placing FEIS Volume 4, Appendix R-2 - Assessment of Species Vulnerability and Prioritization Sierra Nevada Forest Plan Amendment the species at risk, then 1 or 2 outcomes resulted: 1) management direction was developed sufficient to provide for a high likelihood of providing the environmental conditions to maintain viable populations or 2) conclude that management direction at the Sierra Nevada Bioregion scale was too coarse and pass responsibility for maintaining habitat to support viable populations to the specific National Forest. , 7HUUHVWULDO 9HUWHEUDWHV 0HWKRGV The objective of this assessment was to develop a defensible approach for assessing the vulnerability status of all native terrestrial vertebrates within the Sierra Nevada Bioregion and to determine how species in the different vulnerability groups were distributed among the high priority environments at risk (westside foothill oak woodland; late-seral/old-growth forest; and riparian, meadow and aquatic) in the Sierra Nevada (Graber 1996). We used the boundaries of the entire SNEP study area to define the Sierra Nevada Bioregion. We then queried the CWHR to develop a list of species reported to occur within the Bioregion. This resulted in a total of 493 species. We examined the initial list and eliminated “edger” species from further detailed analysis. Edger species were species whose distribution only extended into the edges of the Bioregion and whose primary ranges encompassed vegetation types that predominantly occur in adjacent bioregions to the Sierra Nevada. These were primarily Mojave Desert, Great Basin, Pacific Northwest, and some Central Valley species. We focused the assessment on native species and eliminated exotic species from further evaluation. A total of 427 species were retained for further analysis after this initial filter. We assessed the vulnerability status of 427 native vertebrate species that currently occur or previously occurred prior to European colonization of the Sierra Nevada Bioregion using three variables: population size, population trend, and change in distribution (Table R.1). We focused on these three variables for determining the vulnerability status of a species because they have been widely acknowledged in the scientific literature to be associated with extinction risk. The data for each of these variables were obtained via questionnaire to a single, recognized taxa