Quantitative assessment for forest fire risk based on fire simulation: taking the Subtropical Forest Experimental Center of Chinese Academy of Forestry as an example

  Objective  Forest fire risk assessment is to describe the potential occurrence of forest fire and the direct or indirect fire impacts on environment at the landscape scale by qualitative and/or quantitative indicators. Identifying the areas with high fire risk is the base of forest fire management. Comprehensive assessment on forest fire risk for a region based on burn probability, potential fire behavior, and exposure provides a guide for local fire agency to carry out fire and fuel management.

  Method  We simulated the burn probability, potential fire intensity, spreading speed, and fire types on the landscape scale for the forests in the Subtropical Forestry Experimental Center by the burn probability model (Burn-P3). The potential fire impacts on surrounding communities and water sources were analyzed for exposure. We also analyzed the spatial characteristics of fire risk, burn probability, and potential fire behavior of every vegetation type. A comprehensive assessment model on fire risk was constructed by analytic hierarchy process.

  Result  The fire simulation results showed that the average burn probability of the study area was 0.040 1, and the areas with high and very high burn probability accounted for 5.3% and 2.3%, respectively. The fire types were mainly surface fire and intermittent crown fire. The average fire intensity and spread speed were 2 043.6 kW/m² and 2.5 m/min, respectively. The areas with high and very high fire behavior index accounted for 17.3% and 6.2% of the total areas, respectively. The coniferous and broadleaved mixed forest had the highest rating on burn probability and potential fire behavior index. The broadleaved forest had the lowest grade on burn probability and fire behavior index, but showed the highest exposure. The comprehensive assessment results on fire risk showed that the areas with high and very high risk accounted for 19.7% and 6.5%, respectively. The fire risk of coniferous and broadleaved mixed forest was higher than that of the other vegetation types.

  Conclusion  Most of the study area has low burn probability and high potential fire behavior index. The forests near towns and water sources show high fire risks, which should be the key areas for fire management in the future. It is necessary to carry out fuel cleaning measures to reduce fuel ladder and surface inflammable fuels in coniferous forest and coniferous and broadleaved mixed forest in order to reduce their fire risk.