Fuels reduction treatments achieve long-term restoration goals nationwide
Illustration of overstory, understory, surface fuels, and soil characteristics prior to the FFS (Control) in (A) California, (B) Montana, and (C) North Carolina, our original prescription to change these characteristics so we could meet fuel hazard reduction goals (Original), and how we would change the original prescription given what we know about the development of these prescriptions the last 20 years (Modified future).
Back in 2000, the nationwide “Fire & Fire Surrogate” (FFS) study was created to evaluate the ecological impacts of mechanical treatments (i.e., cutting forest trees and shrubs in the form of harvesting, thinning, and masticating) and prescribed fire in different ecosystems across the United States. These types of restoration treatments are thought to have long-lasting benefits to forests that burned frequently in the past since they return the landscape to more of a historical pattern that can help them withstand future disturbances. Along those lines, the overall goals of the Fire & Fire Surrogate study were to learn how best to promote desirable fire-adapted species, reduce fire hazard, and improve understory diversity across the United States.
We investigated the long-term effects of mechanical treatments and prescribed burning in four regions with different ecosystem types (e.g., conifer- vs. hardwood-dominated) including California (Blodgett Forest Research Station), Montana (Lubrecht Experimental Forest), North Carolina (Green River Game Land), and Ohio (Ohio Hills). Results showed that after 20 years, a combination of mechanical treatments and prescribed fire promoted desired tree species, reduced fire hazard, decreased canopy tree death, and created new crops of vigorous trees. However, the results varied by region. Mechanical treatments (especially when combined with prescribed fire) were most influential on vegetation and fire hazard in western sites (California and Montana). In contrast, mechanical treatments alone promoted poorly adapted tree species in eastern sites (North Carolina and Ohio), indicating a greater urgency for prescribed burning.
Ultimately, these long-term benefits will be strongest when treatments are repeated over time and adapted to local conditions and contemporary goals. This is a key detail, and since forests take a long time to grow and respond to management activities, long-term collaborations like the Fire & Fire Surrogate study network are essential to help us understand how we can tailor restoration treatments to ecosystem type, maintain them through repetition over time, and adjust them to meet new goals and changing conditions. This information can help forest managers fine-tune their forest fuel treatments to prepare for wildfire and better understand the long-term outcomes on productive forests.