Silvicultural approaches to develop Northern spotted owl nesting sites, central Coast Ranges, Oregon

Abstract

The life-story requirements of northern spotted owls (Strix occidentalis caurina), a federally listed "threatened" species, are associated with late-successional habitats. Nesting sites are an important habitat requirement for spotted owls. We used an individual-tree, distance-independent growth model to explore a range of management scenarios for young Douglas-fir stands (age class 50 years) and estimated which scenarios promoted the development of forest patches that emulate the species mix and diameter distributions at known spotted owl nest sites in the central Coast Ranges of Oregon. Our modeling indicates that without silvicultural intervention or natural disturbances, the young stands (170-247 trees/ac) investigated did not develop features associated with spotted owl nest sites within 160-year total stand age. Silvicultural simulations that modeled heavy thinnings at ages 50 and 80 years, followed by tree-planting and additional thinnings developed forest patches structurally similar to our sample of spotted owl nest sites. We infer that silvicultural activities in federally managed, late-successional reserves may need to include alternatives beyond the scope of those permitted under current land use guidelines to accelerate the development of stand structures that better meet the nesting site requirements of spotted owls. Copyright © 2005 by the society of American Foresters.