Comparing fuels reduction and patch mosaic fire regimes for reducing fire spread potential: a spatial modeling approach.

Reduction of fire hazard is becoming increasingly important in managed landscapes globally. Fuels reduction prescribed burn treatments are the most common form of reducing fire hazard on landscapes around the world but often result in homogenized fuel age structures and habitats. Alternatively, the size of unplanned fires, and hence fire hazard, can be reduced by controlling the size and patterning of fuels treatments in a patch mosaic arrangement on landscapes. Patch mosaic burning is being implemented globally as a means to increase heterogeneity to mimic natural fire regime results. Funding for prescribed fire programs is often justified primarily on hazardous fuels reduction with secondary consideration given for ecological effectiveness, which can be increased by particular fire mosaic patterns in some systems. The question we address is: Which of two prescribed fire treatment regimes, fuels reduction or patch mosaic burning, reduces fire hazard most effectively? We address the question using computer simulation modeling on synthetic landscapes representing both fire regime treatments. Treatment scale was important. Among fuel reduction treatments, large blocks burned less area than small blocks. For the mosaic treatments, small blocks reduced fire size the most (out of all treatments) and had the least variance in area burned. It is possible to reduce fire hazard and to provide heterogeneous age fuels structure on the landscape, simultaneously benefiting humans and many native fire-dependent species requiring mosaic habitat patterns.