Combining forest structure data and fuel modelling to classify fire hazard in Portugal

Fire management activities can greatly benefit from the description of wildland fuel to assess fire hazard. A forest typology developed from the Portuguese National Forest Inventory that combines cover type (the dominant overstorey species) and forest structure defined as a combination of generic stand density (closed or open) and height (low or tall) is translated into fuel models. Fire behaviour simulations that accounted for the fire environment modification induced by stand structure resulted in an objective and quantitative assessment of fire hazard for 19 forest types. The range of fire risk is similar between and within cover types. Stand structure, rather than cover type, is the major determinant of fire vulnerability. This indicates a potentially prominent role of stand and fuel management in wildfire mitigation. Four fire hazard groups are defined: (1) open and tall forest types, and closed and tall Quercus suber and diverse forests; (2) closed, low woodlands of deciduous oaks, Q. suber and diverse forests, closed and tall Pinus pinaster woodland and tall Eucalyptus globulus plantations; (3) open and low forest types; (4) dense low stands of P. pinaster, E. globulus and Acacia. Potential fire risk increases from (1) to (4).