Impact assessment of tree spacing on crown fire spread distance for Korean pine stands using a fire simulator

There is a recognized need to apply fuel reduction thinning to the existing young growth pine stands in Korea to reduce catastrophic forest fires. However, thinning guidelines, such as the intensity of thinning treatments or optimal stand density, have not been well established for individual forest stands. In an attempt to identify effective thinning guidelines, we evaluated the effects of different tree spacing on crown fire propagation by simulating fire spread across individual trees using the Wildland-urban interface Fire Dynamics Simulator (WFDS), a physics-based fire spread and behavior model. The results indicate that tree spacing significantly affects the size and intensity of crown fires when all other factors are held constant. Tree spacing that is large enough to remove crown overlaps between neighboring trees appears to be highly effective in reducing crown fire propagation in our simulation.