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

ASSESSMENT OF POST FIRE VEGETATION RECOVERING IN PORTUGAL
Abstract: The years of 2003 and 2005 were the two worst in the historical
record of wildfires in Portugal. In 2003, the country was hit by the most
devastating sequence of large fires, responsible for a total burnt area of 450
000 ha, representing about 5% of the Portuguese mainland (Trigo et al.,
2006). However, in 2005, Portugal suffered again strong damages from forest
fires that affected an area of 300 000 ha of forest and shrub. The years
of 2003 and 2005 are of particular interest since they are both associated
to extreme events, namely the heat wave episode of August 2003 and the
severe drought of 2005.
Based on monthly values, from 1999 to 2008, of the normalized difference
vegetation index (NDVI), at the 1km x 1km spatial scale, as obtained from
the VEGETATION instrument, a methodology is presented that allows identifying
large burnt scars in Portugal and monitoring vegetation recovery
throughout the pre and the post fire periods.
1 - Introduction
C. Gouveia
Escola Superior de Tecnologia de Setúbal (EST)
Instituto Politécnico de Setúbal, Setúbal, Portugal, cmgouveia@fc.ul.pt
CGUL, IDL, University of Lisbon, Lisbon, Portugal
C. DaCamara & R. Trigo
CGUL, IDL, University of Lisbon, Lisbon, Portugal
cdcamara@fc.ul.pt, rmtrigo@fc.ul.pt
Fire represents one of the main disturbances in Mediterranean ecosystems
(Whelan, 1995), having a key role in the dynamics and structure of plant
and animal communities (Gill et al., 1981), that are very inflammable and
have low moisture contents. Plant communities in these ecosystems have
high elasticity after fire because the species are able to regenerate by
means of resprouting from fire resistant structures (Bond and Midgley,
2001), or by germination of fire protected seeds stored in the soil or in the
canopy (Lloret, 1998). Succession after fires usually begins with herbaceous
species, which often recover quickly as a result of the ‘mineral flush’
after fires and their ability to colonize open spaces (Christensen, 1994).
Plant communities frequently evaluate to shrub-dominated populations
with isolated trees, becoming dense forests in the end stage (Röder et al.,
2008). Frequent fires may prevent plants from reaching sexual maturity
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