Accelerating Development of Late-Successional Conditions in Young Managed Douglas-Fir Standards: A Simulation Study

摘要

The goal of this simulation study was to provide information for defining thinning regimes for young Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in the Central Cascades Adaptive Management Area, located in west-central Oregon. Specifically, this study used the ZELIG.PNW (3.0) gap model to evaluate effects of experimental thinning treatments on the development of late-successional attributes and on extracted merchantable volume. Sixty-four thinning treatments were simulated for four rotation intervals (260, 180, 100, and 80 years) starting with a 40-year-old managed Douglas-fir stand. The amount of time for five late-successional attributes to reach defined threshold levels, long-term developmental trends of these attributes, and amount of extracted merchantable volume were recorded for each treatment. Stand conditions of selected treatments were used in a subsequent harvest rotation in which 64 additional experimental thinning treatments were applied and evaluated. A total of 1,744 thinning treatments was evaluated in this study.