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RESEARCH ARTICLE
Contents Vol 18(8)

Spatial and temporal extremes of wildfire sizes in Portugal (1984–2004)

P. de Zea Bermudez A , J. Mendes B , J. M. C. Pereira C , K. F. Turkman A E and M. J. P. Vasconcelos D
+ Author Affiliations
- Author Affiliations

A Departamento de Estatística e Investigação Operacional (DEIO) and Centro de Estatística e Aplicações da Universidade de Lisboa (CEAUL), University of Lisbon, PT-1749-016 Lisbon, Portugal.

B Instituto Superior de Estatística e Gestão de Informação (ISEGI), New University of Lisbon, PT-1070-124 Lisbon, Portugal.

C Deparment of Forestry and Center for Forest Studies, Instituto Superior de Agronomia (ISA), Technical University of Lisbon, PT-1349-017 Lisbon, Portugal.

D Tropical Research Institute, PT-1300-344 Lisbon, Portugal.

E Corresponding author. Email: kfturkman@fc.ul.pt

International Journal of Wildland Fire 18(8) 983-991 https://doi.org/10.1071/WF07044
Submitted: 27 February 2007  Accepted: 8 April 2009   Published: 9 December 2009

Abstract

Spatial and temporal patterns of large fire (>100 ha) incidence in Portugal over the period 1984–2004 were modeled using extreme value statistics, namely the Peaks Over Threshold approach, which uses the Generalized Pareto Distribution (GPD) as a model. The original dataset includes all fires larger than 5 ha (30 616 fires) that were observed in Portugal during the study period, mapped from Landsat satellite imagery. The country was divided into eight regions, considered internally homogeneous from the perspective of their fire regimes and respective environmental correlates. The temporal analysis showed that there does not appear to be any trend in the incidence of very large fires, but revealed a cyclical behavior in the values of the GPD shape parameter, with a period in the range of 3 to 5 years. Spatial analysis highlighted strong regional differences in the incidence of large fires, and allowed the calculation of return levels for a range of fire sizes. This analysis was affected by the presence of a few outlying observations, which may correspond to clusters of contiguous fire scars, resulting in artificially large burned areas. We discuss some of the implications of our findings in terms of consequences for fire management aimed at preventing the occurrence of extremely large fires, and present ideas for extending the present study.

Additional keywords: Generalized Pareto Distribution, Peaks Over Threshold method.


Acknowledgements

This work is partially supported by Fundação para a Ciência e para a Tecnologia, POCTI and Research project PTDC/MAT/64353/2006. We thank two anonymous referees and the associate editor for their careful reading of the manuscript and for their suggestions.


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