Wildfires managed for restoration enhance ecological resilience

Abstract

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.

Contributions of fire refugia to resilient ponderosa pine and dry mixed‐conifer forest landscapes

“…, Barros et al. ). Efforts have also applied landscape simulation models toward the characterization of ecological resilience (Peterson , Keane et al.…”

“…Because fire refugia can occur as relatively discrete forested patches within severely burned landscapes, assessing their capacity to shape post-fire recovery and influence spatial resilience lends itself to spatially explicit landscape simulation modeling approaches. Landscape simulation models are well-suited to explore post-fire landscape dynamics (He and Mladenoff 1999), and they have increasingly been used to assess the effectiveness of interventions to retain forests under varying disturbance scenarios (Halofsky et al 2014, Barros et al 2018. Efforts have also applied landscape simulation models toward the characterization of ecological resilience (Peterson 2002, Keane et al 2018.…”

Prescribed fire regimes subtly alter ponderosa pine forest plant community structure

“…Some suggest wildfires managed for ecological or other resource goals may provide a viable option as well as recognized tradeoffs (Barros et al. ). However, field testing of this hypothesis may be difficult to implement, although some studies focused on tree structure and hazardous fuels are noted (Huffman et al.…”

“…Westlind and Kerns (2017) suggest that an intermediate fire frequency closer to 10 yr in these types of ponderosa pine forests may offer better outcomes related to fuel reduction goals, and this may hold for some plant goals as well. Some suggest wildfires managed for ecological or other resource goals may provide a viable option as well as recognized tradeoffs (Barros et al 2018). However, field testing of this hypothesis may be difficult to implement, although some studies focused on tree structure and hazardous fuels are noted .…”

Twenty‐five years of the Northwest Forest Plan: what have we learned?

“…Given the limitations of restoring landscape patterns and dynamics, vegetation and fuels management would ideally focus on places where it can be most effective and consider broader use of managed wildfire (Barros et al . ). However, communities of people who live and work in fire‐prone landscapes – including homeowners, who should be encouraged to reduce fuels and make structures less susceptible to ignition – must enhance their adaptive capacity and participation in wildfire planning; prescribed fire will also need to become more socially acceptable and receive adequate policy support (Calkin et al .…”