Modeling hazardous fire potential within a completed fuel treatment network in the northern Sierra Nevada

Abstract

We built on previous work by performing a more in-depth examination of a completed landscape fuel treatment network. Our specific objectives were: (1) model hazardous fire potential with and without the treatment network, (2) project hazardous fire potential over several decades to assess fuel treatment network longevity, and (3) assess fuel treatment effectiveness and longevity over a range of two critical fire modeling inputs: surface fuel models and canopy base height. Modeling results demonstrate reductions in the hazardous fire potential across much of the treated landscape, relative to the untreated condition. These reductions persist throughout our modeling duration, 2010–2050. However, there was a strong effect of varying ingrowth levels, which were manipulated to generate different estimates of canopy base height over time, on hazardous fire potential over time. Under the low ingrowth level, which resulted in the highest predictions of canopy base height, hazardous fire potential steadily declined over time for the untreated landscape condition. The effect of varying fuel models in treated areas had much less impact on hazardous fire potential, indicating a robust treatment effect. Our results demonstrate a coordinated fuel treatment network that incorporates local knowledge of fire weather and likely fire behavior patterns can have a substantial impact on reducing hazardous fire potential. However, even with planned maintenance of the treatment network, hazard grows in untreated areas over time, resulting in an increase in overall fire hazard. This suggests additional treatments, including fire use, would be necessary to maintain low hazardous fire potential.