OOS 40-4
Integrated fuel treatments from the site to the landscape on western experimental forests
Restoration and fuel treatments in the dry and moist mixed conifer forests of the northern Rocky Mountains are complex and far different from those applicable to the dry ponderosa pine forests. Due to their complexity, we wanted to develop implement, and evaluate innovative silvicultural methods and systems using concepts from the irregular selection silvicultural system. Questions are: what elements did we learn during implementation, what are the resulting forest conditions, and what is the fire intensity and flame length? We used Black Hills and Boise Basin Experimental Forests (dry forests) and Priest River Experimental Forest (moist forest) as our study sites. We entered into a partnership with the Forest Service, National Forest Systems to implement a replicated study. Depending on the particular experimental forest, studies ranged from 300 ha to 1500 ha in size with treatments focused on creating a variety of canopy openings and soil disturbance as the experimental unit. Spatially explicit plots were established and measured prior to implementation. At Priest River Experimental Forest, the oldest of the studies (9 years) we also conducted surveys after treatments were implemented and six years post-treatment. We conducted a pre- versus post-treatment evaluation using FlamMap and FARSITE wildfire simulations.
Results/Conclusions
In the dry mixed conifer forests the variation in groups varied, indicating one-treatment method is not applicable but should vary depending on the objectives and specific site characteristics. Also we learned that treating vegetation alone does not create fire resilience but also soils also need treatment. We provide the ecological theory and treatment applications concerning soil restoration. In the moist mixed conifer forests we were successful in favoring early and mid-seral species, while maintaining forest characteristics that are relevant to many contemporary forest management objectives. The silvicultural options we developed maintain multiple tree densities, a variety of canopy cover, and enhance old-forest attributes and most importantly, the harvesting, mastication, grapple piling, and prescribed fire treatments we applied will modify both wildfire intensity and burn severity. We found that the heterogeneous forest structures, even with small openings and the minor proportion of the landscape treated, would alter a wildfire’s progression, flame length, and fire type. This analysis showed the placement, juxtaposition, and location of treatments within the landscape would disrupt a hypothetical wildfire’s progression under weather conditions that occurred during one of the worst fire seasons (1967) in the northern Rocky Mountains.