7th Workshop on Forest Fire Management - EARSeL, European ...

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I - PRE-FIRE PLANNING AND MANAGEMENT
2 - Methods
2.1 - National Forest Fire Data Base 1980-2004
The input data was extracted from the Spanish Forest Service (Ministry of
Environment, Rural and Marine affairs), and includes all fire records from
1980 to 2004. The fire records are georeferenced to the UTM grid of 10*10
km. Only those cells with more than 1% of the total area of the grid burned
in the 25 year period were selected for further analysis. A total of 2,957
cells were selected, covering around 56% of the total area of Spain. More
than 320,000 fires were analyzed.
The following fire metrics were used to characteristic fire regimes for each
cell:
• Fire density: ratio of the total number of fires and the cell area.
• Fire frequency: annual average number of fires.
• Fire interannual variability: variation coefficient (ratio of the standard
deviation and the mean of the annual number of fires).
• Fire seasonality: season with largest number of fires.
• Mean fire size: ratio of the burned area and the total number of fires.
• Fire severity: total burned area in different fire sizes.
3 - Results and discussion
3.1 - Description of fire regimes characteristics
Fire density. Average fire density in Spain is 1.28 fires by km 2 , and the standard
deviation is 3.02 fires/km 2 . The higher densities were found in the
Northwest, with a predominant Atlantic climate, the Mediterranean coastal
regions and the central sierras. Medium and low values were found in other
mountainous areas in the South and the Eastern ranges (fig. 1). Fire frequency
shows similar patterns, with average values of 4.33 and a Standard
deviation of 8.98.
Fire seasonality. Most fires in Spain are summer fires, since 56% of all grid
cells have their mode in the summer season (June to August). In these
months, around 40% of all fires occur, and they burn 58% of total affected
area. The spring season (March to May) is the second highest occurrence,
with 24% of all fires affecting to 12% of total burned area. Spring fires are
more common in the northern regions of the country, which also have a second
mode in winter. Most of those fires are related to agricultural practices.
Fire interannual variability is higher in the Mediterranean coast and the
interior mountain areas (fig. 2), since fires are more associated to different
climatic cycles, while in the Northern regions fires are more closely linked
to agricultural practices. The coefficient of variation ranges from 39.6% to
500%. The impact of large fires is quite evident in this regard, which are