Tongass National Forest

Integrated Timber Operability Analysis

There was a need to determine the approximate size and spatial distribution of harvestable timber available under the Forest Plan. This was accomplished by conducting an integrated timber operability analysis, which resulted in a logging system and transportation analysis (LSTA) that covered all lands mapped as suitable for timber harvest. These mapped lands include areas that were determined as not suitable for timber harvest when investigated on the ground, because of unmapped streams, karst features, unstable soils, and other conditions. These unmapped areas were recognized in the 1997 Forest Plan as falldown factors and were estimated to be about 31 percent of the mapped suitable lands. The LSTA development identified these factors through a comprehensive system of resource risk and feasibility codes. The coding reflects knowledge gained from implementing the Forest Plan since 1997 and earlier. The coding structure also allowed more detailed timber sale operability and economic analyses. Overall, this work item involved an analysis of the results of the LSTA and its associated risk and economic factors, along with other Forest Plan factors, to produce an estimate of the forest land that is actually available for timber management during the planning cycle.

Work Product(s): The main work product was a consolidated GIS cover with associated coding. This product assisted in a variety of analyses (including the Spectrum [forest management modeling] analyses) that were necessary for development and comparison of alternatives in the NEPA-associated work in Phases 3, 4 and 5 of the project.