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New forest landscape model predicts how management policies affect future wildfire impacts

Date: May 21, 2020

Integrating the Forest Vegetation Simulator with the FSim wildfire simulation model helps research the effects of different forest management strategies on future wildfire impacts.


Forest landscape models (FLMs) are important tools used to address a wide range of forest management policy tradeoffs on public and private forests. Several recent studies using FLMs have examined the effects of forest and fuels management on future wildfire activity, carbon, water yield, resiliency, and other forest metrics. Studying longer-term (e.g. > 20 years) dynamics between management and disturbances can reveal ecosystem tipping points, feedbacks, and unintended consequences of management activities that are not otherwise observable. Most recently, applications of FLMs have provided insights on the potential effects of management on future fire and forest composition under a range of climate change scenarios. Many of these studies in the United States have used portions of the National Forest network as study areas where wildfires are increasingly impacting ecosystem services and burning into adjacent developed areas. In this study, we developed and applied a new FLM, LSim, to examine a wide range of wildfire and forest management issues on western US landscapes.

A map of the Deschutes National Forest, with the wildland-urban interface marked in red and various treatment areas marked in shades of blue.
A sample of realized treatment locations symbolized by simulation year in blue, based on a scenario that prioritized treatments based on threats to the adjacent wildland-urban interface.

LSim integrates the Forest Vegetation Simulator (FVS) with the large-fire simulation model FSim. The resulting LSim model has the functionality to simulate spatially coordinated forest management over time under a background of large, randomly determined wildfires with models that have undergone decades of field application. This is in contrast to other FLMs that have yet to be used to guide site specific management activities as part of forest and fuels management on national forests. The LSim model provides a platform to simulate detailed prescriptions developed by silviculturalists in the field as part of forest landscape management projects.  

We applied the model to the Deschutes National Forest in central Oregon, USA, to study how accelerated forest restoration might affect future wildfire. We simulated three alternative spatial treatment scenarios and three levels of management intensity (area treated) over a 50-year timespan and measured the response in terms of area burned, fire severity, wildland-urban interface exposure, and timber production. 

We are also applying the model to national forests in the Blue Mountains in eastern Oregon to study the effect of climate change on future fire. At a third study area in northern Arizona we are examining alternative restoration and fire management strategies through time on fire behavior.  

Key Findings

  • A map of the Deschutes National Forest with fire perimeters scattered throughout, marked in different colors depending on year.
    Map of simulated fire perimeters color-coded by fire year during a single run of a scenario that prioritizes treatment of stands with higher potential fire severity.
    The backlog of areas in need of restoration on the Deschutes National Forest could be eliminated in 20 years when the treatment rate was elevated to 3× the current level. However, higher rates of treatments early in the simulation created a future need to address the rapid buildup of fuels associated with understory shrub and tree regeneration.
  • Restoration treatments over time had a large effect on fire severity, reducing potential flame length by up to 26% for the study area within the first 20 years, whereas reductions in area burned were relatively small.
  • There was substantial inter-annual variability in area burned, illustrating the possibility of alternative future landscape conditions under the same management policy.
  • We also observed simulated fires that exceeded four times the historically recorded fire size. Very large fires can homogenize fuels and eliminate clumpy stand structure that historically reduced fire size and maintained landscape resiliency. 
  • The LSim model has immediate potential applications in a range of studies concerning the combined and independent effects of fire and management on fire regimes, feedbacks, stand structure, forest patch size distributions, carbon, wildfire, habitat, amenity protection, and economics.

 

Featured Publications

Ager, Alan ; Barros, Ana M. G. ; Houtman, Rachel ; Seli, Rob ; Day, Michelle A. , 2020


Principal Investigators: 
Principal Investigators - External: 
Ana MG Barros - Washington State Department of Natural Resources
External Partners: 
Rachel Houtman, Oregon State University