Fire risk
Fire risk is determined by the particular composition of vegetation and therefore both by its flammability and combustion capacity and its capacity to recover after fire. Mediterranean vegetation type is highly flammable and combustible due to the existence of species with high content of resins or essence oils (Fig. 47). Fire risk has been estimated on the basis of the structure and the dominant vegetation species present in each study site. The following categories of fire risk have been defined: (a) low, including perennial crops, annual crops such as maize, tobacco, sunflower, etc.; (b) moderate, including annual crops such as cereals or meadows, deciduous oaks, mixed deciduous and evergreen oaks, mixed Mediterranean maquis and evergreen forests; (c) high, including Mediterranean maquis; and (d) very high, including coniferous forests.
The number of field sites in which the indicator fire risk was recorded was rather limited (295 field sites in 7 study sites) (Table 6). Based on the obtained data, the dominant class of fire risk as identified was low (Fig. 48), covering 72.9% of the total field sites and corresponding in the majority of the study sites in which this indicator was defined. The next important class of fire risk was very high covering 17.3% of the total field sites and corresponding mainly to the Mação- Portugal study site. Moderate and high fire risk has been recorded in 4.4% and 5.5% 0f the study field sites, respectively.
Fig. 47. Examples of areas with low fire risk (olive grove, left) and very high fire risk (pine forest, right)
Fig. 48. Distribution of fire risk class of the various types of vegetation identified in the study field sites
