# Mapping the Most Susceptible Regions to Fire in Portugal
## 4 Discussion  
Portugal is one of the Mediterranean countries with higher burned area extension [10]. Fuel accumulation, steep mountains, and fragmented landscapes due to abandoned rural properties, in association with increasing prolonged droughs and hot conditions such as those in 2003, 2005 or 2017 [55; 56; 57], are key factors for the enhancement of fire risk in many regions. Therefore, an assessment of the critical areas that show a greater susceptibility to burning is an essential task. [PERSON] et al. [58] identified a pronounced likelihood of increased fire weather conditions with 2 \({}^{\circ}\)C global warming over the Mediterranean region as a whole, and Portugal, in particular, has already been experiencing hotter and drier conditions during summer [59]. In fact, the results of our work showed a general increase in the probability of occurrence of the most severe classes of FWI during the last years. Therefore, more intense and frequent extreme hot and dry conditions, linked to enhanced positive vegetation productivity trends (GPP/NPP and NDVI) in the Iberian Peninsula [60; 61], may promote more fire events that have the potential to become more severe. In this context, a more extensive analysis regarding the wildfires' characteristics in Portugal over the last years, namely fire frequency, fire energy, and fire risk, but also elevation, fuel accumulation in ecosystems, and vegetation activity, is called for. [PERSON] and [PERSON] [62] described the transition of fire regime changes in the western Mediterranean, from the twentieth century to the present day, as fuel-limited to hot and dry driven, by pointing out that climate conditions have been exacerbating their role in wildfires amplification, surpassing the influence of land use changes in these events. On the other hand, [PERSON] and [PERSON] [63] and [PERSON] et al. [22] highlighted that the fire activity in Portugal is strongly modulated by land use conflicts and fragmented landscapes with a prevalence of highly unmanaged flammable vegetation. In our work, the results of the PC showed a strong signal over regions with high fuel accumulation over several months, which highlight that, in Portugal, fuel management continues to be a key factor for fire propagation, flammability, and intensity. Therefore, although we do not directly address an analysis for hot and dry conditions in ecosystems, our results of fire weather conditions are in line with [PERSON] and [PERSON]'s [62] insights. Moreover, the results also agree with [PERSON] and [PERSON] [63] observations, in the way that the extreme fire seasons in Portugal are strongly linked to the association of fuel accumulation availability with hot and dry conditions, which was also pinpointed by [PERSON] et al. [18] and [PERSON] et al. [19]. Some of the most susceptible areas to fire have burned in the last years, especially in 2017, when wildfires devastated the central part of the country [10; 19; 20]. Our analysis relied on a dataset of around 20 years (depending on the variable) and indicated that, despite the recent occurrence of fire events, those areas constitute a hotspot and have a great potential to burn in the near future. Moreover, the results also show that the most extreme classes of fire susceptibility were found over areas mainly covered by shrulands and forest, such as eucalyptus, or a mixture of both. Considering that shrulands and eucalyptus are vegetation types very prone to wildfire spread, this can constitute an enhancement of the fire risk over these areas. The quality assessment of the PCA was performed for the fire season of 2022 in Portugal. The analysis of the PC\({}_{\text{REC}}\) signal distribution across the top 5 burned areas allowed the observation that fire susceptibility was mainly high to extreme. The A1 event revealed several spots classified as extremely susceptible to fire.