Guiding preventative wildland fire mitigation policy and decisions with an economic modeling system.

The protection of private residences from wildland fire produces high levels of cost and safety risk to firefighters, especially with the expanding ex-urban settlement pattern in the wildland urban interface (WUI). Economic information on probable structure losses can help guide efficient wildfire management, policy, and investments. However, no single existing modeling tool is capable of accurately predicting existing wildland fire ignition risk to WUI residences, nor are there broadly accepted models to calculate needed investments to reduce risk to WUI structures. To fill this void, a representative set of rural residences in western Montana was selected to estimate a baseline, 30-year wildland fire ignition hazard and the cost effectiveness of optional investments to reduce risk from wildfire damage to these residences. The study applied a modeling system combining outputs from a structure ignition assessment model (SIAM) with wildland fire probabilities from an ecological disturbance model (SIMPPLLE). Results indicate that the probability of structure damage to a home when a fire visits a residence is 1.0 under conditions of extreme wildland fire weather. This contrasts with the low probabilities (0-0.05) that wildland fire will reach vegetation surrounding the residence. Cost-effectiveness analysis of two suites of preventative mitigation strategies demonstrated that home mitigation zone investments (modifying houses or fuels within 30.5m (100ft) of a residence) are generally more cost effective in reducing risk to WUI structures than investments in silvicultural operations in surrounding forests (within 2.4km (1.5mi) of homes). The effectiveness of the mitigation options in modifying average home loss due to wildfire ranges from negative 19.6% to positive 63% (some silvicultural treatments did increase the probability of wildfire in simulations). While both home ignition zone mitigations and silvicultural treatments can markedly reduce wildland fire hazard estimates, the former appear to provide a more pronounced reduction in hazard as correlated with expenditures.