Agricultural and Forest Meteorology 237 (2017) 50–59 Contents lists available at ScienceDirect Agricultural and Forest Meteorology j o ur na l ho me pag e: www.elsevier.com/locate/agrformet Assessing the role of drought events on wildfires in the Iberian Peninsula Ana Russo ∗ , Célia M. Gouveia, Patrícia Páscoa, Carlos C. DaCamara, Pedro M. Sousa, Ricardo M. Trigo Instituto Dom Luís, Faculdade de Ciências da Universidade de Lisboa, Campo Grande Edifício C8, Piso 3, 1749-016 Lisbon, Portugal a r t i c l e i n f o Article history: Received 2 February 2016 Received in revised form 24 January 2017 Accepted 29 January 2017 Keywords: Drought Fires Standard precipitation index Standard precipitation evapotranspiration index Iberian Peninsula a b s t r a c t Southern European countries are particularly affected by summer wildfires and drought events. The occurrence of extreme meteorological conditions during preceding and contemporaneous months ampli- fies the risk of summer wildfires. The main scope of this study was to investigate the impact of drought periods on burned areas in the Iberian Peninsula. This will be achieved through the comparison of time series of two widely used multi- scalar drought indices (SPI and SPEI) calculated for each province and then associated with the time series of the standardized logarithm of normalized burned areas during the fire summer season. The SPI and SPEI were both calculated for the time scales spanning between 2 to 12 months and for each month from January to August, between 1980 and 2005. Based on the regression analysis between drought indicators and burned areas, the months that present lowest errors were identified for each province. From the obtained results two main conclusions were reached: (i) the association between drought and fires is a local scale process and should be analyzed at the province or sub-province level rather than at the country or continental level; (ii) the relation between wildfires and drought is better explained by the influence of the spring precipitation on the central sector and by the influence of temperature and precipitation during summer on most of the Portuguese provinces. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Wildfire has a major role in the dynamics of a variety of ter- restrial ecosystems, in particular the Mediterranean ones (Bastos et al., 2011), affecting both biodiversity and human activities. It is now widely accepted that the main drivers of fire ignition and propagation are (1) the presence of fuel (i.e. biomass/vegetation) (Flannigan et al., 2009; Gouveia et al., 2012); (2) favorable weather patterns often amplified by appropriate climate conditions preced- ing the fire season (Flannigan et al., 2009; Pereira et al., 2011); (3) socioeconomic conditions that affect land use/land cover patterns, fire-prevention and fire-fighting capacity (Flannigan et al., 2009; Pereira et al., 2011) and (4) the local topography (Pereira et al., 2011). Mediterranean ecosystems are prone to forest fires (Salis et al., 2014) and over the last decades there has been an increase in the ∗ Corresponding author at: Instituto Dom Luiz, Faculdade de Ciências da Univer- sidade de Lisboa, Campo Grande, Edifício C8, Piso 3, Sala 8.3.15A., 1749-016 Lisboa, Portugal. E-mail address: acrusso@fc.ul.pt (A. Russo). number of extremely large fires as well as in the extent of wildfires in some Mediterranean regions (e.g. Pereira et al., 2011; Pausas and Fernández-Mu ˜ noz, 2012; Salis et al., 2014). These fires caused extensive economic and ecological losses, and even human casual- ties (Salis et al., 2014). Mediterranean Europe is a region particularly susceptible to cli- mate change (Giorgi and Lionello, 2008) and some of the changes associated with global warming (e.g. reduction of precipitation, increased temperature and increased frequency of extreme events such as droughts and heat waves) have strong implications on the fire regimes (Pausas and Fernández-Mu ˜ noz, 2012; Koutsias et al., 2013; Salis et al., 2014; Sousa et al., 2015). Mediterranean European fire regimes are sensitive to changes in human behavior and in land use patterns (Bastos et al., 2011; Salis et al., 2014) either as part of agro pastoralism, accidental ignitions, criminal intent or even land abandonment (Salis et al., 2014). During the last decades the western Iberian Peninsula (IP) has been particularly affected by summer wildfires, namely in Portugal, where the years 2003 and 2005 were especially outstanding (Trigo et al., 2013a). The above mentioned fire-seasons were both par- ticularly exceptional registering, in 2003, the maximal burnt area http://dx.doi.org/10.1016/j.agrformet.2017.01.021 0168-1923/© 2017 Elsevier B.V. All rights reserved.