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A Review of the Main Driving Factors of Forest Fire
Ignition Over Europe
A. Ganteaume, A. Camia, M. Jappiot, J. San Miguel-Ayanz, M. Long-Fournel,
C. Lampin
To cite this version:
A. Ganteaume, A. Camia, M. Jappiot, J. San Miguel-Ayanz, M. Long-Fournel, et al.. A Review of
the Main Driving Factors of Forest Fire Ignition Over Europe. Environmental Management, Springer
Verlag (Germany), 2013, 51 (3), p. 651 - p. 662. �10.1007/s00267-012-9961-z�. �hal-00860797�
A review of the main driving factors of forest fire ignition over Europe
Anne Ganteaume
A,C
, Andrea Camia
B
, Marielle Jappiot
A
, Jesus San-Miguel-Ayanz
B
, Marlène
Long-Fournel
A
, Corinne Lampin
A
A
: IRSTEA, UR EMAX, CS 40061, 13182 Aix-en-Provence, France
B
: European Commission, Joint Research Centre (JRC), 21027, Ispra (VA), Italy
anne.ganteaume@irstea.fr
andrea.camia@jrc.ec.europa.eu
marielle.jappiot@irstea.fr
jesus.san-miguel@jrc.ec.europa.eu
marlene.long@irstea.fr
corinne.lampin@irstea.fr
C
Corresponding author: Tel.: + 33 4 42 66 69 79, Fax : + 33 4 42 66 99 23
Email address: anne.ganteaume@irstea.fr
Additional key-words: ignition factors, fire occurrence, Mediterranean region
Abstract
Knowledge of the causes of forest fires, and of the main driving factors of ignition, is an indispensable
step towards effective fire prevention policies. This paper analyses the factors driving forest fire ignition in the
Mediterranean region including the most common human and environmental factors used for modelling in the
European context. Fire ignition factors are compared to spatial and temporal variations of fire occurrence in the
region, then are compared to results obtained in other areas of the world, with a special focus on North America
(US and Canada) where a significant number of studies has been carried out on this topic.
The causes of forest fires are varied and their distribution differs among countries, but may also differ
spatially and temporally within the same country. In Europe, and especially in the Mediterranean basin, fires are
mostly human-caused mainly due arson. The distance to transport networks and the distance to urban or
recreation areas are among the most frequently used human factors in modelling exercises and the Wildland-
Urban Interface is increasingly taken into account in the modelling of fire occurrence. Depending on the socio-
economic context of the region concerned, factors such as the unemployment rate or variables linked to
agricultural activity can explain the ignition of intentional and unintentional fires. Regarding environmental
factors, those related to weather, fuel and topography are the most significant drivers of ignition of forest fires,
especially in Mediterranean-type regions. For both human and lightning-caused fires, there is a geographical
gradient of fire ignition, mainly due to variations in climate and fuel composition but also to population density
for instance. The timing of fires depends on their causes. In populated areas, the timing of human-caused fires is
Author produced version of the article published in Environmental Management, 2013, 51, 3, 651-662
Original publication available at www.springer.com
doi:10.1007/s00267-012-9961-z
closely linked to human activities and peaks in the afternoon whereas, in remote areas, the timing of lightning-
caused fires is more linked to weather conditions and the season, with most such fires occurring in summer.
1. Introduction
Early in the Holocène, high climate seasonality favoured fire expansion in southern Europe, as it did in many
other ecosystems of the northern and southern hemispheres. Later on, during the Neolitic Age, humans began
affecting the fire regime that was previously related only to climatic conditions, leading to higher fire frequency
(Vannière et al. 2008). Since then, fire plays a critical role in the structure and functioning of many ecosystems,
especially in the Mediterranean basin but also in the other Mediterranean-type areas of the world (Naveh 1975;
Gill et al. 1981; Keeley and Keeley 1988; Richardson and van Wilgen 1992). In these regions, human-caused
fires are the most common (Keeley 1982; Kruger and Bigalke 1984; Vazquez and Moreno 1993; Fuentes et al.
1994) contrary to other regions such as the boreal forests, where lightning is often the major cause of ignition
(Johnson, 1992). Despite its importance, knowledge of human causes of wildfires is still very limited (Lovreglio
et al. 2006), although it is widely recognized that they can vary considerably.
In Europe, forest fires mostly affect Mediterranean regions where, on average, 85% of the annual
burned area is recorded (San Miguel and Camia 2010). The main drivers of fire ignition are interconnected and
evolve along parallel overarching trends to those of the human society and its use of forest resources. Socio-
economic developments in recent decades have led to changes in life patterns, with increasing mobility of
people, spread of tourism and recreational activities and the resulting increase in the number of visitors to the
forest. Additionally, in many rural areas of Mediterranean Europe, fire is a traditional and long established
management tool. Its ancient and current use in agriculture, silviculture and livestock breeding is well
documented (Bonora et al. 2002; Carmona-Moreno et al. 2005; Moreira et al. 2009). The traditional rural socio-
economic systems that once characterized the Mediterranean region collapsed in the last few decades, resulting
in a rural exodus in the northern part of the Mediterranean basin (e.g., in Spain, Italy and Greece; Hill et al.
2008), and an overexploitation of natural resources in the eastern regions (e.g., Turkey, Lebanon and Cyprus). In
parallel, huge, rapidly occurring land-use changes have taken place, including urbanization of coastal areas with
the development of tourism and the construction of infrastructures, which have created conflicts and additional
driving factors of forest fires. All the above-mentioned societal patterns have resulted in changes in fire ignition
causes in the last decades.
The existence of a wide range of fire causes significantly complicates the assessment of fire risk since
the factors that drive fire ignition have to be modelled, including human and environmental variables, as shown
in several works (Bar Massada et al. 2009; Martínez et al. 2009; Thompson et al. 2011). Despite its importance,
the influence of human factors on the spatial and temporal patterns of wildfire occurrence needs to be better
understood (Sturtevand and Cleland 2007; Shlisky et al. 2007). As in Moreira et al. (2011) and Ricotta et al.
(2012), fire risk is defined in this paper as “the chance of a fire starting as determined by the presence and
activity of any causative agent” (FAO 1986; NWCG 2006), independently of how large the fire may become.
Furthermore, fire hazard is defined as “a fuel complex, defined by volume type, condition, management and
location, that determines the degree of ease of ignition and the resistance to control” (Hardy 2005; Moreira et al.
2011); fire hazard being thus connected to biomass availability.
Author produced version of the article published in Environmental Management, 2013, 51, 3, 651-662
Original publication available at www.springer.com
doi:10.1007/s00267-012-9961-z
This paper aims at analysing the factors driving forest fire ignition, focusing on the European
Mediterranean region. The study addresses the most common human and environmental factors of fire
occurrence used for modelling in the European context. Fire ignition factors are compared to spatial and
temporal variations of fire occurrence in the region. The analysis is mostly based on literature review, but it is
also supported by results obtained processing data from the European Fire Database – EFD (Camia et al. 2010)
of the European Forest Fire Information System (San-Miguel-Ayanz et al. 2012). Our results are then compared
to those obtained in other areas of the world, with a special focus on North America (USA and Canada) and
Australia where a significant number of studies has been carried out on this topic.
2. Human factors
Human agents are of great importance in fire risk assessment in Mediterranean countries where they are the main
cause of forest fires either by accident/negligence or by deliberate action (arson) (Henderson et al. 2005).
Analysis of data on fire causality in the EFD shows that, during the 2006-2010 period, the cause of forest fires in
the Mediterranean countries was identified and recorded for 71% of the events. Of those fires with known cause,
55.8% were due to deliberate action, 33.5 % to negligence, 6.1% to accident and 4.7% to natural causes. In Table
1 these figures are compared with those of northern and central Europe. In northern European countries, the
relative frequency of deliberate fires is remarkably lower (13.9%), while 78.8% of the fires are recorded as
caused by accident or negligence; fires due to natural causes are also much higher in number (7.8%). In central
Europe, the share of deliberate fires is similar to that of the Mediterranean countries, while the incidence of
natural causes is very low (0.5%). Overall, when all regions are considered together, it is observed that 97.1% of
fires in Europe are directly or indirectly caused by human agents.
Table 1 Relative frequency of fires by main fire causes in Europe in 2006-2010 (fires with known causes). Data
elaborated from the European Fire Database (Europe North: Estonia, Finland, Latvia, Lithuania, Sweden; Europe
Centre: Bulgaria, Germany, Hungary, Poland, Romania, Slovakia, Slovenia, Switzerland; Europe South
(Mediterranean): France, Greece, Italy, Portugal, Spain)
Fires of known cause
(% of total fires)
Fire causes (% of fires of known cause)
Natural
Accident
Negligence
Deliberate
Europe North
80%
7.3%
14.1%
64.7%
13.9%
Europe Centre
87%
0.5%
3.8%
39.3%
56.4%
Europe South
71%
4.7%
6.0%
33.5%
55.8%
Early attempts to model human-caused fire occurrence were based on indirect assessments of human activity
using demographic indicators or data on generic accessibility to forested areas (Cunningham and Martell 1976;
Altobellis 1983; Donoghue and Main 1985). Later on, several spatial analyses of fire occurrence explored the
role of spatially explicit factors such as distance to roads, location of recreational areas or distance to urban
settlements (Chuvieco and Congalton 1989; Vega-García et al. 1995; Alexandrian 1995; Russell-Smith et al.
1997; Follin 1999; Cardille et al. 2001; Pew and Larsen 2001; Vasconcelos et al. 2001; Decarnin 2002;
Prestemon and Butry 2005; Mollicone et al. 2006; Maingi and Henry 2007; Vasilakos et al. 2007; Yang et al.
2007). Indeed, the analysis of human-caused fire occurrence requires a comprehensive assessment, integrating in
one framework spatially explicit variables related to human activities (e.g. location and distance to
Author produced version of the article published in Environmental Management, 2013, 51, 3, 651-662
Original publication available at www.springer.com
doi:10.1007/s00267-012-9961-z
infrastructures such as roads, railways, power lines, populated areas or recreational sites, the configuration of
wildland/urban interface areas) as well as socio-economic variables and indicators affecting human ignition (e.g.
unemployment rates, age of rural populations, population density, housing density, etc.). Many authors have
shown that a large number of fire ignitions can be explained by the first group of factors (Langhart et al. 1998;
Mangiavillano 2004; Lampin et al. 2005 and 2006; Badia-Perpinya and Pallares-Barbera 2006; Catry et al. 2007;
Romero-Calcerrada et al. 2008; Vasilakos et al. 2008; Martínez et al. 2009; Padilla and Vega-García 2011). On
the other hand, socio-economic indicators such as the unemployment rate have also been shown to be clearly
linked to fire occurrence in many areas of southern Europe (Ferreira de Almeida et al. 1992, Leone 1999,
Chuvieco et al. 1999, Velez 2000, Sebastian-Lopez 2008). Catry et al. (2007) observed that more than 70% of
the fire ignitions in Portugal occurred in the municipalities with the highest population densities (more than 100
inhabitants per km
2
), that 85% of the fires occurred close to urban areas (i.e. located at a distance of less than
500 m) and that 70% occurred close to main roads (at a distance of less than 500 m). Similarly, Romero-
Calcerrada et al. (2008) suggested that, in Spain, the increasing presence of people near woodlands and socio-
economic trends may have been producing wildfire ignition patterns that increasingly resemble those in
Mediterranean-type regions with historically stronger economies such as California. These authors found clear
evidence for a positive relationship between the intensive use of the territory and the ignitions in forest areas,
with a significantly higher occurrence of fires in the vicinity of urban areas and transport networks (at a distance
of between 50 and 250 m from urban areas and less than 50 m from tracks). This trend was also underlined in the
work of Padilla and Vega-García (2011). However, the spatial distribution of fires in relation to these factors
may reveal different tendencies. According to Alexandrian and Gouiran (1990), in France, some fires occurred
close to roads, around highly populated towns or in forest fragmented areas, whereas other fires were ignited
near isolated dwellings in large forest stands. Other authors, such as Archibald et al. (2009), confirmed the
positive relationship between population density and occurrence of fires; however they showed that,
simultaneously, there was also a decrease in the total area burned with increasing human densities because of the
decrease in mean and maximum fire size.
It has been hypothesised that the higher wildfire occurrence observed in recent years is linked to
landscape homogenisation due to land use changes (Duguy 1998; Farina 1998). Land use and land cover changes
that occurred in the last decades in Mediterranean Europe have been generally increasing fire hazard (Moreira et
al. 2011). Indeed, the abandonment of rural areas implies an increase in shrubland and forest areas and a
corresponding decrease in grassland and cultivated land. The colonisation of agricultural fields by natural
vegetation tends to simplify the traditional landscape mosaic and at the same time increases fuel loads (Romero-
Calcerrada and Perry 2004; Badia-Perpinya and Pallares-Barbera 2006; Vasilikos et al. 2008; Koutsias et al.
2012). However, it is questionable whether this process increases fire ignition probability rather than fire hazard.
In fact, Catry et al. (2007) found that, in Portugal, most ignitions occurred in agricultural (60%) and social/urban
areas (25%), while only 15% of the ignitions occurred in forested or uncultivated areas. Similar results were
found in the European Mediterranean area by Santos de Oliveira et al. (2009). Ricotta et al. (2012) showed that,
in a Mediterranean region of Italy, the decreased human pressure following agricultural land abandonment
lowered fire ignition probability. In regions where the proportion of agricultural land remains high (for instance
Spain, southern Italy or Slovakia), one of the main causes of fire is the negligent use of fire in agricultural
practices like burning stubble (Tuček and Majlingova 2009; Lovreglio et al. 2010; Figure 1), which is also linked
Author produced version of the article published in Environmental Management, 2013, 51, 3, 651-662
Original publication available at www.springer.com
doi:10.1007/s00267-012-9961-z
