Land managers implement fuel treatments on the landscape to reduce fire severity and to restore ecosystem function. Several different methods may be used individually or in combination, including prescribed fire and mechanical thinning of understory shrubs and small trees. A frequent debate revolves around whether the effects of fuel treatments in reducing fire severity and burn probability are limited to their spatial extent or whether they benefit the broader landscape in which they are sited. We employed stochastic fire modeling to investigate this question. Specially, we modeled 10,000 years of fire weather, fire ignitions, fire growth, fire suppression, and fire cessation in the FSim model. We assumed that fuel treatments reduced ground fuels (as prescribed fire would be expected to do) and reduced canopy cover. We chose a well-studied area in the Sierra Nevada mountains of California with a frequent fire regime.
Results/Conclusions
Results indicate that fuel treatments reduced burn probabilities by 48-60% within the treatment footprint. The reduction in burn probability was greater when more of a zone was treated, and decreased rapidly with the percentage of a zone treated. The reduction in burn probability from a fuel treatment declined rapidly with distance from its edge, with effects beyond 500m-1km being negligible. Flame lengths shifted from higher to lower classes, suggesting that fire severity would decline on average. The probability of high intensity fire within the treatments decreased by a mean of 90%. These results have implications for planners looking to prevent damage to highly valued resources (including habitat) from fire or to restore low severity fire regimes.