Human dimensions of wildfires in NW Spain: causes, value of the burned vegetation and administrative measures

Composition of the sample

The percentage of women and men in the sample (57% of women and 43% of men) did not differ significantly from that in the population (${\chi }_{\mathrm{1d.f.}}^2=2.978$, P = 0.084). Respondents were between 18 and 92 yrs old, and there were significant differences between the proportion of age groups in our sample compared to the population (${\chi }_{\mathrm{2d.f.}}^2=29.087$, P < 0.001), with a lower percentage of young adults (18–45 yrs old; 21% in our sample vs. 34% in the population), and a higher percentage of both middle-aged (45–65 yrs old; 46% in our sample vs. 40% in the population) and senior adults (>65 yrs old; 33% in our sample vs. 25% in the population). Regarding educational level, 27% of respondents had lower educational level, 49% had a medium level and 24% had higher educational levels, percentages that did not differ significantly from those in the population (${\chi }_{\mathrm{2d.f.}}^2=1.891$, P < 0.389). Respondents living in urban areas reached 71% and 29% resided in rural areas, while the percentage of respondents doing some activities in nature was 48% vs. 52% of respondents doing no activities in nature.

Social perception of the frequency of fire causes

Respondents perceived the general causes of wildfires (accidental, negligent, deliberated and natural causes) as being different in terms of frequency of fires caused by them. There were some differences (although small) between male and female participants and educational levels in the relative frequency they assign to different causes, as revealed by the significant interactions with these factors (Table 1), although the same general trend was observed for all demographic groups. Deliberate causes were considered as the most frequent fire causes, followed by negligent, accidental and, last, by natural causes, perceived as the less frequent (Fig. 1). Men assigned more frequency than women to deliberate causes and less to negligence (Fig. 1A). Differences between men and women were smaller in regard to the frequency of accidents and natural causes (Fig. 1A). Differences associated with the educational level were also small but there was a trend to assign more frequency to deliberate causes among people with medium and high educational levels, while the lower the educational level the higher the perceived frequency of accidental and natural causes (Fig. 1B). The perception of deliberate as the most frequent followed by negligent causes was realistic, in accordance with official fire reports (Fig. 1). Accidents and natural causes have similar frequencies according to official reports, but accidents were considered more often as more frequent than natural causes by respondents (Fig. 1).

When looking at the more specific fire causes (Question 2 in the questionnaire; Appendix A), again the population perceived them as differing in frequency, but with no differences between demographic groups in their perceptions (no significant interactions between causes and demographic groups; Table 1). Fires caused by pyromaniacs (mentally ill people) and those caused for profit were considered the most frequent, being clearly overestimated compared to official reports (Fig. 2). These were followed by fires caused for vegetation management, which were rightly considered as quite frequent, although underestimated with respect to fires caused by mentally ill people or for profit. The rest of causes, that followed in terms of perceived frequency, were all overestimated, as they cause a relatively small number of fires according to official reports, with ranching being the most frequent among them (Fig. 2). Ranching was perceived as similarly frequent as natural causes, hunting or conflicts, while it brings about ca. 3.5 to 4 times more fires than those causes (5.5% of fires compared to less than 1.6%).

Social perception of the risk associated with different types of vegetation

There were significant differences between vegetation types in their risk of fire, as perceived by the population (Table 1). Overall, pine plantations, eucalypt plantations, shrublands and mixed forested areas were considered the most fire prone, while native oak forests and agricultural fields were considered as having lower risk of fire (Fig. 3), as is broadly confirmed by real data (Calviño-Cancela et al., 2016; Calviño-Cancela et al., 2017). There were differences between some demographic groups in their perception of the risks: between male and female participants, between people that performed activities in nature and people that do not, and depending on the level of education (significant interactions with these factors, although only marginally significant for the educational level; Table 1). Women perceived shrublands as relatively riskier compared to men, and the same with eucalypt plantations, although differences with men were smaller for this type of vegetation (Fig. 3A). People not performing activities in nature perceived all vegetation types as more risky than people performing activities in nature, with differences being more pronounced for native oak forests and, to a lower degree, agricultural fields and eucalypt plantations (Fig. 3B). In regard to the educational level, there was a perception of higher risk associated with shrublands as the educational level increased, while differences regarding other vegetation types were smaller (Fig. 3C).

Social perception of the value of different types of vegetation

There were significant differences between vegetation types in regard to their value for respondents (Table 1), assessed as the importance of the loss in case of a fire. Overall, native oak forests were the most appreciated by the population, followed by pine plantations, mixed forested areas, eucalypt plantations, agricultural fields and, last, shrublands. But this pattern differed depending on the place of residence (urban vs. rural areas) and the educational level (significant interactions with these factors; Table 1). Respondents in rural areas gave more value to eucalypt plantations and agricultural fields than people in urban areas. In regard to educational levels, differences were especially noticeable for eucalypt plantations, which were more valued by respondents with lower educational level, recording a similar score to that of pine plantations, while respondents with higher educational levels gave eucalypt plantations the lower score together with shrublands (Fig.  4).

Social perception of the role of the administration

Most people considered that the administration was doing less than enough in the fight against wildfires (83%; Question 5 of the questionnaire; Appendix A), while 17% considered that the administration was doing enough, and less than 1% considered that they were doing more than necessary (Fig. 5). There was a significant effect of the place of residence and of the educational level on this perception (Table 2), with the percentage of people considering that the administration was doing less than necessary being higher among people from rural areas than from urban areas, and also among people with medium educational level (Fig. 5).

In regard to the importance of improving administration measures in the fight against wildfires (Question 6 of the questionnaire; Appendix A), all the proposed measures attained high scores (3.5 to 4.7 on average, in a scale from 1, lowest importance, to 5, highest), which means that the population considered important to improve all measures, but with differences between measures and a significant interaction with the educational level (Table 1). The improvement of preventive measures and a more restrictive legislation were the measures considered as the most important for respondents, while measures related with fire extinction (increasing the efforts in extinction and reducing the reaction times) were considered, in comparison, less important. Respondents with higher educational levels considered more important the improvement of all measures, but this trend was especially clear for legislative measures (for a more restrictive legislation and harder punishment), environmental education and plantation of fire-resistant species (Fig. 6).

The social perception about the effectiveness of the law that makes fuel reduction compulsory in the wildland urban interface was uniform among demographic groups (Table 2). About half of the respondents (51%) considered this an effective measure but difficult to implement by landowners, 28% of people considered it an ineffective measure and 21% considered it effective and feasible to implement by landowners.

Social perception of the frequency of fire causes

Respondents demonstrated being aware of the importance of deliberate causes of wildfires in the region, rightly considering them as the most important causes of wildfires. Although the general trend was the same among demographic groups, it is interesting to note the increase in the perceived importance of causes in which humans have a clear responsibility (deliberate causes) among people with higher educational levels, in contrast with respondents with lower educational levels, which gave more importance than the more educated to natural causes and anthropogenic but involuntary causes (accidental). This might be related to a more questioning attitude of the more educated people regarding human responsibility for environmental problems (Díez-Nicolás, 2006).

In regard to more specific causes, the role of pyromaniacs (mentally ill people) was clearly overestimated, as was that of deliberate fires caused for profit. The incidence of fires caused by pyromaniacs is often overestimated, not just by the general population but even by fire reporters and officials, due to the poor understanding of this mental disorder, so that the term pyromaniac is often wrongly applied to people that set fires deliberately (arsonists in the strict sense), even when no mental illness has been diagnosed (Doley, 2003 and references therein). However, it is important to note that, in our questionnaire, we referred to pyromaniacs explicitly as mentally ill people, so that the overestimation does not come from an inappropriate use of the term but from a wrong perception of the real incidence of this cause. The terms arsonist and pyromaniac are regularly used interchangeably in the media, despite their very different meanings and implications, and this contributes to creating confusion in the population. Pyromaniacs engage in intentional and pathological firesetting, while arsonists wilfully and maliciously set fire (or aid in setting fire). Of those arrested for the crime of arson, ca. 10% are considered to be mentally ill (Barker, 1994). A good understanding of deliberate firesetting behaviours is important for improving strategies to control and manage fire ignitions. An important aspect in this regard is recidivism and associated risk factors. The rate of firesetting recidivism is relatively low compared with the rate of general redicivism related to other offences (more than 55% of firesetters have subsequent charges for any offence while only c. 5% have subsequent charges for firesetting; Ducat, McEwan & Ogloff, 2015). The highest probability of re-offending is in the first two years, and recidivist firesetters are likely to have mental disorders (Ducat, McEwan & Ogloff, 2015 and references therein).

The consideration of vegetation management as less important than pyromania and profit-driven fires was unrealistic, since it is, in fact, the most important specific cause in the study area (33% of fires; period 2006–2011). This was due to an overestimation of pyromania and of fires caused for profit rather than to an underestimation of the frequency of fires related to vegetation management. These fires correspond mostly to agricultural burnings for waste disposal. Their high frequency has led authorities to develop strict regulations in this regard, banning all agricultural burnings in summer and making it compulsory to ask for specific permits the rest of the year, so that rangers are aware and can supervise the burning. There is a lack of awareness in the population about vegetation management being a major cause of wildfires, which highlights the importance of information campaigns, since the effectiveness of preventive measures depends on the wise behaviour of thousands of landowners that dispose of their vegetal waste every year. The strategy followed by the administration to reduce the high incidence of vegetation management as a cause of wildfires has been based on imposing strict regulations. However, farmers still use fire as a management tool, and this causes a great number of fires every year. Reducing the risk of this routine practice is needed. To this end, education and training campaigns especially focused on this particular cause of wildfires should be promoted, in order to raise awareness of the danger involved as well as to show how to improve safety when using fire.

Ranching was rightly considered as relatively infrequent but somewhat underestimated in comparison with other causes such as natural causes, hunting or conflicts. Fires related to ranching occur mainly in shrublands (Calviño-Cancela et al., 2017), where fire is traditionally used in relation to extensive livestock grazing, to provide a flush of nutritious re-growth (Webb, 1998). The incidence of ranching was higher outside the wildland urban interface (ca. two times higher; Calviño-Cancela et al., 2017), thus far from populated areas, which may contribute to a relative underestimation in comparison with other causes. The rest of causes specified in the questionnaire have lower incidence in the study region (<2% each).

Social perception of the risk associated with different types of vegetation

The realism of public perceptions about the fire risk associated with different vegetation types, considering agricultural fields and oak forests as the less fire prone, is in accordance with real data (Calviño-Cancela et al., 2016; Calviño-Cancela et al., 2017), which is noticeable. This is especially so in the case of oak forests since, despite their similarity to tree plantations in terms of structure, respondents clearly differentiated them in terms of fire risk. Of all the land covers considered in Calviño-Cancela et al. (2016), oak forests had the lowest ignition risk which, pooling together areas within and outside the wildland-urban interface, was 2.7 and 22 times lower than in “pure” eucalypt and pine plantations, respectively (considering pure plantations those with at least 70% dominance of eucalypts or pines, respectively). This difference is even higher when compared with mixed plantations, where eucalypts or pines are still dominant but have lower land covers. Oak native forests in the region, in contrast with pine and eucalypt plantations, are characterized by the deep shade provided by their canopies, which leads to lower temperature and higher moisture under the canopy, and limits the growth of biomass (Calviño-Cancela, Rubido-Bará & Van Etten, 2012), all contributing to reduce the risk of ignition. In addition, the high content in flammable volatile essential oils of pine and eucalypt leaves adds in flammability (Dimitrakopoulos & Papaioannou, 2001; Schwilk & Ackerly, 2001). Although oak forests were rightly considered less risky than tree plantations and shrublands, they were perceived as riskier than agricultural fields, when they are in fact ca. 4 times less risky (in the whole territory, pooling together the areas within and outside the wildland-urban interface; Calviño-Cancela et al., 2016). However, native forests are indeed riskier than agricultural fields in the wildland-urban interface (Calviño-Cancela et al., 2016), i.e., areas closer to most of the population, which likely contributes to a more widespread perception of the risk associated with this type of vegetation in the general population. Interestingly, people engaged in activities in nature considered all vegetation types less risky than people not performing those activities, which might be related to a higher tolerance of the risk by people obtaining a benefit from the recreational use of the vegetation (Slovic, Fischhoff & Lichtenstein, 1982).

Social perception of the value of different types of vegetation

The higher perceived value of tree-dominated vegetation compared to treeless formations coincides with a previous study in the same area upon which vegetation with trees was perceived as more attractive than shrublands (for 96% of respondents; Lage-Picos, 2001). A low preference for treeless environments has been shown by a number of studies in Europe, the USA and Australia (e.g., Lamb & Purcell, 1990; Cook & Cable, 1995; Kiley et al., 2017). The preference for native forests over plantations in our study seems to be more related to the aesthetic or perceived ecological value of these formations rather than to their economic value, since plantations provide more revenue. In fact, the European public attaches higher value to forest conservation and protective functions than to forest utilisation aspects, and the preservation of biodiversity is perceived as one of the most important functions of forests, with no significant differences among regions (European Commission, 2009). This may reflect a societal trend towards a greater appreciation of natural values and a more critical attitude towards resource exploitation (European Commission, 2009). In addition, oaks, the dominant trees in native forests, are, together with chestnuts (also abundant in these forests) the most appreciated trees by the Galician public, while eucalypts are the least valued (Lage-Picos, 2001). This seems to be related to the native compared to alien status of species, with oaks and pines being considered native by most people (although some frequently planted pines such as P. radiata are non-native in this region) while eucalypts are recognized as alien species (Lage-Picos, 2001). It is noticeable the low value perceived of shrublands, which, in addition to their low economic profitability (used almost exclusively for extensive ranching nowadays) are usually perceived as having low natural value compared to tree-dominated communities (Lage-Picos, 2001). However, shrublands harbour a rich native biodiversity in this region, with many species of conservation concern (Calviño-Cancela, Rubido-Bará & Van Etten, 2012; Calviño-Cancela, 2013). Regarding agricultural fields, their perceived value increases in rural areas, where there are obviously more farmers, and therefore greater awareness of their economic importance, than in urban areas. Rural people often express higher preference for scenes of agriculturally modified landscapes than do urban people (Orland, 1988). Eucalypt plantations were also more valued in rural areas, which may also be related to their economic importance there. In a region where most forest land is in private hands, sales of eucalypt wood have a significant impact on household income in rural areas (Cátedra, 2015). But the most remarkable aspect in relation to the perceived value of eucalypt plantations is the pattern observed with educational level: the higher the educational level, the lower the valuation of eucalypt plantations. The value of eucalypt plantations was similar to that of pine plantations for people with lower educational level but was one of the least valued for higher-educated people. As commented, eucalypt plantations are a significant source of income in rural areas but have a very limited ecological value, harbouring less biodiversity than pine plantations, native oak forests or shrublands in the study region (Calviño-Cancela, Rubido-Bará & Van Etten, 2012; Calviño-Cancela et al., 2013, Calviño-Cancela, 2013). In addition, eucalypts are non-native in this area and have an invasive character (Sanz-Elorza, Dana & Sobrino, 2001; Richardson & Rejmanek, 2011), being able to spontaneously spread in native forests, plantations and shrublands (Calviño-Cancela & Rubido-Bará, 2013; Calviño-Cancela, Lorenzo & González, 2018). Its limited value from the point of view of biodiversity conservation, in addition to its non-native status and the environmental problems associated with non-native species (Pimentel et al., 2001) might explain its perceived low value for higher-educated respondents. The educational level tends to be positively correlated with environmental awareness (Liordos et al., 2017; Vaske, Jacobs & Sijtsma, 2011), with more educated people tending to give relatively more importance to environmental aspects over exploitation aspects (Teel & Manfredo, 2010).

The perceived value of vegetation types might affect their ignition risk, for the efforts each individual is willing to invest in preventing fires might be correlated to the value attributed to each type of vegetation. In fact, a previous study has found a negative relationship between the price of the land and the number of fires and the area burned, so that more expensive land is less affected by fires (Barreal, Loureiro & Picos, 2012). Social perceptions can also affect priorities in firefighting operations. For instance, shrublands are perceived as having low value and this may increase both the risk of ignition, very high in this land cover, and the size of fires, for firefighters often concentrate their efforts in more valued land covers (Moreira et al., 2009).

Social perception of the role of the administration

The survey reveals a general poor perception of the role of the administration, which, according to most respondents, is not doing enough in the fight against fires. This negative perception increased among urbanites, which have a less direct contact with wildfires and administrative measures in the field, so that their negative perception may have been influenced by media filters (Jacobson, Monroe & Marynowski, 2001). The improvement of preventive measures, including legislative reforms and environmental education, was considered the most important, especially by respondents with higher education level, while the improvement of extinction measures was considered less critical, similarly for all levels of education. The trend in the number of fires and the area burned in the last four decades (1976–2015; PLADIGA, 2014–2017) gives support to this perception: the area burned per decade has followed a steady downward trend (of 25% to 35% per decade), despite an ascending trend in the number of fires in the three decades from 1976 to 2005 (of 85% to 120% per decade), which suggest that extinction measures are being more effective than measures to prevent new ignitions. In fact, prevention remains as the biggest challenge: only in the last decade has a decrease in the number of fires been finally achieved (of 65% compared to the previous decade; PLADIGA, 2014–2017), but it remains as one of the highest rates in Europe, with 0.13 fires per km² on average, only exceeded by Portugal (European Commission, 2016). As recommended by FAO (2007), policymakers should move from a reactive attitude after the fire outbreak to a proactive approach of planning and prevention. This should translate to increasing budgets for prevention and decreasing funding for suppression, which should be less needed.

Among preventive measures, developing legislation to prevent people to get economic benefits from wildfires was especially favoured by respondents overall. This reflects a common perception of fires being still used by some for profit, with legislative action being perceived as an important measure to prevent fires. The need for education campaigns was especially favoured by people with higher educational level, who tended to be more critical with the role of the administration. Information campaigns can influence public acceptance of management strategies (Shelby & Speaker, 1990). However, wildfire prevention campaigns in the study region are usually targeted to the general public using mass media, are often superficial in their content and do not usually provide useful information to help individuals avoid risky behaviours. Approaches in which the public are just passive recipients of information without being involved in reciprocal action do not usually produce significant changes in perceptions or behaviours (Beringer, 2000). More constructive campaigns focused on education and active training to specific segments of the population are recommended, in particular to improve awareness of the risk involved in some activities, such as the use of fire for vegetation management in agriculture, and to provide information on how to improve safety when using fire. Awareness is essential since it increases motivation to engage in action to prevent wildfire risks and, without motivation, interventions to improve knowledge and training often have modest impacts on behaviours (Visser, Holbrook & Krosnick, 2007).

Preventive measures against wildfires are often focused on fuel reduction (e.g., in Spain; MAGRAMA, 2012). Fuel management is often controversial worldwide (Gill, Stephens & Cary, 2013). Lack of public support can result in failure to implement fuel management strategies adequately (Toman et al., 2011; Ryan, Knapp & Varner, 2013). Understanding the social acceptability of fuel management strategies is therefore of great importance for their success (Toman, Shindler & Brunson, 2006). Previous research on public attitudes toward fuel reduction techniques has focused primarily on prescribed burning (Manfredo et al., 1990; Jacobson, Monroe & Marynowski, 2001), which is very seldom used in the study region. In fact, in a study on practitioner perceptions of wildland fire management across South Europe and Latin America (Molina-Terren, Cardil & Kobziar, 2016), the North of Spain (including the study region) was the region with the lowest affinity for prescribed fire use: most respondents believed that prescribed fire did not have positive ecological effects and half thought that it was not socially acceptable, although most people were of the opinion that this practice would increase in the future. Fuel reduction in the study region is usually performed by mechanical thinning, which involves removing or altering the structure of trees or understorey to reduce the amount of combustible fuels, in order to reduce fire intensity and to change fire behaviour. Common arguments against this practice include its high cost, visual impact, reduction in available habitat for plant and animal communities, water quality and potential to favour weeds (Winter, Vogt & Fried, 2002; Brooks et al., 2006). In our study, although most respondents considered the law that compel landowners to reduce fuels in the wildland-urban interface as effective, half of respondents considered it difficult to implement. In fact, the degree of compliance of the law is low and the risk of ignition in these interfaces remains high (more than 50% higher within the wildland-urban interface than outside, (Calviño-Cancela et al., 2016). The NW of Spain has very good conditions for the growth of biomass (Riesco, 2004), thus fuel management requires a constant effort. The high cost of implementing this measure reduces its effectivity, for many landowners choose not to obey the law, despite the consequent risk of being punished. A less costly alternative could focus on the establishment of fire-resistant vegetation. In this regard, it is important to highlight the low fire risk of native oak forests, which have also high resistance and resilience to fire (Proença, Pereira & Vicente, 2010), and can establish naturally in most areas in this region (Izco, 1987), thus requiring minimal management efforts. The use of fire-resistant species as a management measure against fires was considered relatively important by the population, especially by the more educated, and oak forests were rightly perceived as having low fire risk and were highly valued by the people. Favouring the use of this type of vegetation as an alternative to fuel reduction, both within and outside the wildland-urban interface, would thus represent a socially acceptable measure with likely positive outcomes, both in terms of biodiversity conservation an economic sustainability. Increasing the economic sustainability in the fight against wildfires is crucial, since the previously commented positive outcomes in terms of reducing the area burned come at a very high cost. The annual spending of the Government in this regard goes as high as $50 of public money per ha of wildland (period 2014–2017, PLADIGA, 2014–2017). This is difficult to sustain in the long term, thus finding affordable fire management options becomes a priority. Integrated approaches based on fuel management that take advantage of the adaptations of the native vegetation can constitute effective alternatives that maximize the ecological benefits while minimizing socio-economic impacts (Hirsch et al., 2001; Fernandes, 2013).