Author(s):
Moreira, Francisco 
; Catry, Filipe X. ; Rego, Francisco Castro ; Bacao, Fernando
Date: 2010
Persistent ID: http://hdl.handle.net/10400.5/4242
Origin: Repositório da UTL
Subject(s): fire; land cover; accessibility; population density; landscape management; Portugal
Description
Not all wildfire ignitions result in burned
areas of a similar size. The aim of this study was to
explore whether there was a size-dependent pattern
(in terms of resulting burned area) of fire ignitions in
Portugal. For that purpose we characterised 71,618
fire ignitions occurring in the country in the period
2001–2003, in terms of population density in the
local parish, land cover type and distance to roads.
We then assigned each ignition into subsets of five
classes according to the resulting burned area:[5 ha,
[50 ha,[100 ha,[250 ha,[500 ha. The probability
of an ignition resulting in different burned area
classes was modelled using binary logistic regression,
and the relative importance, strength and signal
(positive or negative) of the three explanatory
variables compared across the models obtained for
the different classes. Finally, we explored the implications
of land cover and population density changes
during the period 1990–2000 in Portugal for the
likelihood of ignitions resulting in wildfires[500 ha.
Population density was the more important variable
explaining the resulting burned area, with the probability of an ignition resulting in a large burned
area being inversely related to population density. In
terms of land cover, ignitions resulting in large
burned areas were more likely to occur in shrubland
and forest areas. Finally, ignitions farther away from
roads were more likely to result in large burns. The
current land cover trends (decrease of agricultural
land and increase in shrublands) and population
trends (decline in population densities except near the
coast) are increasing the probability that ignitions
will result in large fires in vast regions of the country.
