Simulating forest fuel and fire risk dynamics across landscapes—LANDIS fuel module design

Understanding fuel dynamics over large spatial (103–106 ha) and temporal scales (101–103 years) is important in comprehensive wildfire management. We present a modeling approach to simulate fuel and fire risk dynamics as well as impacts of alternative fuel treatments. The approach is implemented using the fuel module of an existing spatially explicit forest landscape model, LANDIS. The LANDIS fuel module tracks fine fuel, coarse fuel and live fuel for each cell on a landscape. Fine fuel is derived from vegetation types (species composition) and species age, and coarse fuel is derived from stand age (the oldest age cohorts) in combination with disturbance history. Live fuels, also called canopy fuels, are live trees that may be ignited in high intensity fire situations (such as crown fires). The amount of coarse fuel at a given time is the result of accumulation and decomposition processes, which have rates defined by ecological land types. Potential fire intensity is determined by the combination of fine fuel and coarse fuel. Potential fire risk is determined by the potential fire intensity and fire probability, which are derived from fire cycle (fire return interval) and the time since last fire. The LANDIS fuel module simulates common fuel management practices including prescribed burning, coarse fuel load reduction (mechanical thinning), or both. To test the design of the module, we applied it to a large landscape in the Missouri Ozarks. We demonstrated two simulation scenarios: fire suppression with and without fuel treatment for 200 years. At each decade of a simulation, we analyzed fine fuel, coarse fuel, and fire risk maps. The results show that the fuel module correctly implements the assumptions made to create it, and is able to simulate basic cause–effect relationships between fuel treatment and fire risk. The design of the fuel module makes it amendable to calibration and verification for other regions.