Restoration Treatment Effects on Stand Structure, Tree Growth, and Fire Hazard in a Ponderosa Pine/Douglas-Fir Forest in Montana
Crown fires that burned thousands of ha of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests in recent years attest to the hazardous conditions extant on the western landscape. Managers have responded with broad-scale implementation of fuel reduction treatments; however. because threats to pine forests extend beyond fire, so too must the approaches to address them. This western Montana study evaluated four treatments in a randomized complete block experiment for their effects on stand structural characteristics, growth increment, and crown fire potential. Evaluation of control, burn-only, thin-only, and thin-burn treatments showed that the combined thin-burn treatment had the greatest number of desired effects, the burn-only had the fewest, and the thin-only was intermediate. The thin-burn significantly reduced stand density, canopy cover, torching hazard, and crowning hazard and increased average diameter, height-to live-crown, and basal area increment; the thin-only reduced stand density, canopy cover, and crowning hazard and increased average diameter and basal area increment; and the burn-only reduced torching hazard and increased height-to-live crown. These structural and growth effects are related to or influence numerous stand/ecosystem properties at our site, including diameter distributions, species composition, large-tree development potential, overall tree vigor, potential for shade-intolerant tree regeneration, and resiliency to fire. Results demonstrate that well-designed restoration treatments can promote key short-term stand and ecosystem responses while significantly reducing crown fire potential.