Wildfires managed for restoration enhance ecological resilience

Expanding the footprint of natural fire has been proposed as one potential solution to increase the pace of forest restoration programs in fire‐adapted landscapes of the western USA. However, studies that examine the long‐term socio‐ecological trade‐offs of expanding natural fire to reduce wildfire risk and create fire resilient landscapes are lacking. We used the model Envision to examine the outcomes that might result from increased area burned by what we call “restoration” wildfire in a landscape where the ecological benefits of wildfire are known, but the need to suppress high‐risk fires that threaten human values is also evident. Our study area, in the eastern Cascades of Oregon, USA, includes the Deschutes National Forest where large tracts of mixed conifer forest structure are outside the historical range of variation and characterized by multi‐layer, closed‐canopy stands. We found that simulation of one restoration wildfire per year in addition to high‐risk wildfires in the regular fire season and over the course of 50 yr resulted in a 23% increase in total area burned, but the same probability of fire‐on‐fire interactions. This translated into 0.3% of the national forest burned by restoration wildfire per year and had a small impact in area burned by high‐risk fires albeit more likely in extreme fire years. Smoke production doubled in the restoration scenario relative to the scenario without restoration wildfire, but still resulted in minimal smoke production in most years. Restoration fires burned with low‐ to mixed‐severity and led to a steady reduction in canopy cover and increase in resilient forest structure in dry‐forest types. Habitat for the federally protected northern spotted owl declined with the inclusion of restoration fire, while habitat for species that use recently burned forest stands (e.g., black‐backed woodpecker) increased. Our results suggest that restoration wildfire can improve forest resilience and contribute to restoration efforts in fire‐adapted forests, but there are trade‐offs (wildlife habitat, smoke, area burned in fire‐sensitive forest types), and the level of restoration fire use we simulated is unlikely to have a significant impact on the occurrence of high‐severity wildfires.