Evaluating Silvicultural Options at Landscape Scales: Case Studies from the Central Cascades Adaptive Management Area

John Cissel, Fred Swanson, Allison Reger, Cascade Center for Ecosystem Management, Blue River, OR

A longstanding goal of the science-management partnership centered on the HJ Andrews Experimental Forest has been to use landscape-scale case studies as a way to foster integrated thinking about ecosystem structure and function, and to develop and test these ideas through implementation, monitoring, and modeling activities. Direction given to the Central Cascades Adaptive Management Area (CCAMA) in the Northwest Forest Plan reinforced this goal, and provided a framework for further development of landscape plans in the CCAMA. Results from three landscape-scale case studies are presented.

The Blue River Landscape Study is a large scale, long-term effort to develop and monitor the effectiveness of an alternative landscape management strategy. The strategy uses historical disturbance regimes as a general model for management activities intended to achieve the objectives of the Northwest Forest Plan: late-successional habitat, aquatic ecosystems, and sustainable timber production. Timber harvest and prescribed fire are used to create future stand and landscape patterns more similar to historical landscapes than past or current practices. Results show that this approach will produce more late-successional habitat, larger patches, more interior habitat, and less edge between old and young forests. This is expected to more fully benefit species associated with late-successional habitat. Additional analyses are underway.

A second case study illustrates the use of landscape modeling to compare six alternative strategies intended to sustain old forests. We portray simple structural dynamics at the patch scale over a 600-year modeling horizon using the TELSA (Tool for Exploratory Landscape Scenario Analysis) model. In the short term, elimination of timber cutting in old stands maintains old forests. An intermediate term (50-200 years) view points out the importance of policies for management of existing mature forests as these forests are the potential old forests of the next century. To sustain Douglas-fir dominated old forests in the very long term requires occasional regeneration of Douglas-fir forests. Policies intended to sustain old forests across the landscape should integrate consideration of successional and disturbance dynamics at multiple temporal and spatial scales.

A current case study is intended to explore landscape strategies for young stand management in the Fall Creek Late-Successional Reserve. Previous modeling work at the stand scale produced a database depicting the effects of alternative thinning regimes on five late-successional habitat characteristics over a 200 year time-period. A TELSA model for Fall Creek has been designed and constructed to display the effects of these thinning regimes on late-successional habitat characteristics across space and time. Maps and graphs show the rate at which individual habitat characteristics develop over the watershed based on the mix of thinning regimes applied.