LANDSCAPE MANAGEMENT USING HISTORICAL FIRE REGIMES: BLUE RIVER, OREGON

Abstract

Landscapes administered for timber production by the U.S. Forest Service in the Pacific Northwest in the 1950s-1980s were managed with dispersed patch clear- cutting, and then briefly in the late 1980s with aggregated patch clear-cutting. In the late 1990s, use of historical landscape patterns and disturbance regimes as a guide for landscape management has emerged as an alternative to the static reserves and standard matrix pre- scriptions in the Northwest Forest Plan. Use of historical information to guide management recognizes the dynamic and variable character of the landscape and may offer an improved ability to meet ecosystem management objectives. We describe a landscape management plan based in part on interpretations of historical disturbance regimes. The plan contains a reserve system and other landscape areas where three distinct types of timber harvest are prescribed. Timber harvest prescriptions approx- imate the frequency, severity, and spatial extent of past fires. Future harvest blocks are mapped and used to project forest patterns 200 yr forward and to map resulting landscape structure. This plan is compared with an alternative plan for the same area based on the extensive reserves and prescriptions for matrix lands in the Northwest Forest Plan. The management approach based on historical patterns produced more late-successional habitat (71% vs. 59%), more overstory structure in young stands (overstory canopy cover of 15-50% vs. 15%), larger patches (mean patch size of 48 vs. 26 ha), and less edge between young and old forest (edge density of 19 vs. 37 m/ha). While landscape structures resulting from both plans are historically unprecedented, we feel that landscape management plans incorporating key aspects of ecosystem history and variability may pose less risk to native species and ecological processes.