Mapping the Causes of Forest Fires in Portugal by Clustering Analysis

Ana C. Meira Castro,Luciano Lourenço,António Sousa,Adélia Nunes

doi:10.3390/geosciences10020053

Ana C. Meira Castro, Luciano Lourenço + Show 2 more

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https://doi.org/10.3390/geosciences10020053

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Abstract

This paper presents a spatial characterization of the distribution at district level of the forest fire events that occurred in mainland Portugal between 1996 and 2015 and whose causes were investigated. We further examine the breakdown of the causes of these forest fires over this period. Results supported by relevant validated statistics show that of the total fire events recorded, 94.4% were identified as an effective occurrence, of which 22.2% had burned an area greater than 1 ha, and of these only 42.1% were investigated. False alarms or fires without a recorded burning area are more significant in the districts of Aveiro, Lisbon and Porto, the biggest municipalities. Of the fires whose causes were investigated, the largest number of recorded events were in NE regions (49.0%), followed by NW regions (41.7%), and finally in the rest of the country (9.3%). Taking into account the ratio between the investigated fires and the total number of fires and the behavior profile produced for cluster analysis, a different panorama is brought to light, with the center and south regions showing greater effort to investigate the fires. A thorough analysis of the causes and motivations of the ignition of these forest fire occurrences showed that human activity, either deliberate (20.4%) or negligent (29.9%), outweigh natural phenomena (0.6%). Reactivations (14.6%) and Unknown (34.5%) causes decreased as time passed, whereas negligent and deliberate causes increased. However, these results could change if the percentage of unknown information in relation to the origin of the forest fires is considerable. The outcome of this research will support an efficient management related to fire mitigation and suppression including establishing preventive actions to reduce the occurrence of forest fires and emphasize the need to improve the procedure for recording forest fire events in Portugal, especially in relation to identifying their cause.

Highlights

Fire is one of the major drivers of ecosystem dynamics in European Mediterranean landscapes, as it has affected soil and vegetation composition for millennia [1,2]
The outcome of this research will support an efficient management related to fire mitigation and suppression including establishing preventive actions to reduce the occurrence of forest fires and emphasize the need to improve the procedure for recording forest fire events in Portugal, especially in relation to identifying their cause
Several scientific papers have been published in recent years that support the strong relationship between the incidence of forest fires and climatic and meteorological features in European countries (e.g., [3,4,5,6]), while other studies report that the causes of forest fire ignitions are mainly anthropogenic (e.g., [5,7,8,9,10,11])

Summary

Introduction

Fire is one of the major drivers of ecosystem dynamics in European Mediterranean landscapes, as it has affected soil and vegetation composition for millennia [1,2]. Several scientific papers have been published in recent years that support the strong relationship between the incidence of forest fires and climatic and meteorological features in European countries (e.g., [3,4,5,6]), while other studies report that the causes of forest fire ignitions are mainly anthropogenic (e.g., [5,7,8,9,10,11]). The human factors that are commonly linked to fire ignition are the forest-agricultural or forest-urban interface constraints related to land use management, social conflicts arising from unemployment, rural poverty, hunting disputes or from the inappropriate use of the fire recreation activities. These anthropogenic sources of Geosciences 2020, 10, 53; doi:10.3390/geosciences10020053 www.mdpi.com/journal/geosciences. Geosciences 2020, 10, 53 fire ignition are known to be related to fire persistence and seasonality, while fire density patterns are associated with variables of specific climates and vegetation cover [12].

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