Recovery Plan for the Northern Spotted Owl - DRAFT

IntroductionThis appendix presents the criteria and procedures that were used to delineatethe designated conservation areas (DCAs) that form one of the main buildingblocks of the Northern Spotted Owl Recovery Plan. It also provides informationthat can be used to compare the effects on federal lands of the recovery planwith other plans proposed for conservation of northern spotted owls or oldgrowthforests. These plans include the Interagency Scientific Committeereport (Thomas et al. 1990) and two of the alternatives presented by theScientific Panel on Late-Successional Forest Ecosystems (Johnson et al. 1991).Description of the Plans ConsideredInteragency Scientific CommitteeThe Interagency Scientific Comimittee (ISC) proposed a series of reserves fornorthern spotted owls and management guidelines for intervening forests onfederal lands (Thomas et al. 1990). The reserves are called habitat conservationareas (HCAs). The design of the reserves was based on empirical informationon spotted owls and concepts and modeling from the field of conservationbiology. Criteria used to map the reserves are summarized here.Mapping criteriafrom the ISC report1. Map HCAs that will support a minimum of 20 currently known or estimatedpairs of spotted owls. Size of HCAs should be determined usingknown owl locations, density and median home range size, and sitespecificgeographic and topographic information.2. Where HCAs cannot be made large enough to support 20 pairs owing tonatural or human-induced limitations, provide category 2 HCAs supportingtwo to 19 pairs. Again, determine size using known owl locations,density and median home range size, and site-specific geographic andtopographic information.3. Provide for single-pair (category 3) HCAs where category 1 HCAs currentlycannot achieve objectives. Median home range size should be used todetermine target size.4. Space category 1 HCAs a maximum of 12 miles edge-to-edge andcategory 2 HCAs a maximum of 7 miles.5. Consider both currently and potentially suitable habitat in designatingthe area such that suitable habitat in the future will be as contiguous aspossible.6. The shape of areas should be as nearly circular as possible to minimizeperimeter/area ratio.In addition to the HCA network, the ISC report recommended management ofintervening forests under the 50-11-40 rule. This rule requires that 50 percentof the federal forested area in each quarter-township be managed to maintainan average dbh of at least 11 inches and canopy closure of at least 40 percent.This same matrix management rule was proposed for all other options discussedhere. The effects of the 50-11-40 rule are not included in this evaluation.587