1Fire is a part of many ecosystems (Bento‑Gonçalves et al., 2012), and it has served forest clearing throughout time, both for agriculture and grazing, thus taking on the role of crucial “ecological factor” for development or regression of forest systems around the world.
2In the Mediterranean, its role has been particularly relevant due to a combination of very special characteristics that make the Mediterranean ecosystems different from others around the world, a result of its weather characteristics and prolonged and intense human presence, and its influence on fire (Pausas and Vallejo, 1999).
3The first evidence of change introduced by man through fire, in the Mediterranean landscape, dates back to the Neolithic period (Naveh, 1975). Since then the Mediterranean Basin has witnessed the evolution of many cultures, some of them densely populated and, most of them, users of fire. This specificity, of ancient and intense human intervention in the use of soils, is obvious, especially in the European portion of the Mediterranean Basin, where humans have used fire as a tool to control and change their surroundings more intensely than in other Mediterranean regions (Wainwright, 1994; Grove, 1996; Margaris et al., 1996; Goldammer et al., 2007).
4Although fire has shaped Mediterranean ecosystems, fire occurrence schemes, meaning, their frequency and intensity, have changed. The natural cycle of fire has been reduced (Pereira et al., 2006), fires have become recurrent (Ferreira-Leite et al., 2011), their intensity and expansion have increased, and they have taken on catastrophic proportions and have lost their role as catalysts of the renewal of ecosystems (Noss et al., 2006).
5A set of socio-economic changes, which took place during the second half of the twentieth century in European Mediterranean countries, seems to have contributed to a scenario where fires are, not only more plausible, but also more difficult to extinguish, due to the considerable amounts of biomass accumulated over the years (Lourenço, 1991; Vélez, 1993; Moreno et al., 1998; Rego, 2001). This combined with very unfavourable weather conditions (Lourenço, 1988; Pyne, 2006) fuels catastrophic fires, thus resulting in an increase in burned areas (Ferreira‑Leite et al., 2014).
6Even if the number of large forest fires is statistically irrelevant in Portugal, when compared to the total number of occurrences, it is still the main factor behind most of the annual burned area. Despite this being a statistically relevant increase in the number of large forest fires over the last ten years, there is a slight trend toward the increase in the expansion of large forest fires, expansion which is proportional to the size of the fire (Ferreira‑Leite et al., 2011/2012).
7The evolution of forest cover in Portugal has followed, over the years, a pattern which is shared by the Mediterranean region, the destruction of original forestland through frequent fires to make way for grazing grounds, the use of the best soils for cereal culture and the use of wood as fuel and as a construction raw material (Andrada and Silva, 1815; Ferreira Borges, 1908; Rego, 2001). However, the phenomenon described is not that of a contemporary perspective of forest fires, but that of slash-and-burn carried out by man to make way for his activities or for his own protection.
8The first known written references to forest fires date back, in our country, to the end of the twelfth century, and its harmful effects produced an almost complete change in Portugal’s forest cover and consequent aggradation of many rivers. For example, the erosion problems in the Mondego basin are well known, as well as the subsequent Royal intervention, in 1464, through Royal Charter in which King Afonso V ordered “at the city’s request and to avoid continued damage caused by the aggradation of the Mondego, that no fires should be set on the shores of the Mondego from Coimbra to Seia [about 90 km].”
9With the disintegration of the rural world (Bento-Gonçalves et al., 2010), especially after the 70s, we have witnessed an increase in forest fires and burned area in our country (fig. 1).
Fig. 1 – Evolution of the number of occurrences and burned area, between 1981 and 2012
Source : ICNF (2012)
10It is often thought that large forest fires are a recent phenomenon in Portugal, but this is not true, as they have been a common reality since, at least, the nineteenth century. What has changed is their frequency and, most of all, media attention.
11For statistical purposes, in Portugal and until very recently, the Institute for the Conservation of Nature and Forests (Instituto de Conservação da Natureza e das Florestas -ICNF) defined Large Forest Fire (LFF) as any fire which covered an area of more than 100 ha. Nowadays, the official definition is 500 ha, so established by Parliament Resolution no 35/2013, 19th March (D.R. no. 55, Series I).
12Based on fire statistics made available by the ICNF (ICNF, 2012), in the 1981-1990 decade LFFs (fires with a burned area above 100 ha) represented 1.6% of the total number of occurrences recorded in those ten years, the seemingly most significant value of the last three decades, since in the following decades (1991-2000 and 2001-2010) it was only 0.7%.
13However, there was an actual increase, with 30% more LFFs in the second decade when compared to the first decade, and over 10% more LFFs in the third decade. Therefore, what we have seen is not a decrease but a substantial increase in LFFs, even if in terms of the total number of occurrences there has been a decrease. This resulted only from a three-fold increase from the first to the second decade, with continued increase in the third decade (Table 1).
Table 1 ‑ Occurrences and large forest fires (≥100 ha) in mainland Portugal by decade
Source of data : INCF (2012)
14Nevertheless, if there was a significant increase in the number of LFFs during the period analysed, in terms of burned area the increase was even more considerable, having doubled from the first to the third decade, thus leading to an increase in the percentage of burned area and, consequently, an increase in the average area of LFFs (Table 1).
15If we observe the information regarding large forest fires in the last 30 years, we will see that the most frequent LFFs were those which burned areas between 100 and 500 ha, representing on average 77.9% of the total number of LFFs, and were responsible for 40.3% of the area burned by LFFs during that period. For LFFs over 500 ha, the most frequent ones were those which burned areas between 1 000 and 5 000 ha, representing 8.7% of the total, and were responsible for 30.9% of the area burned by LFFs (Table 2).
Table 2 ‑ Large forest fires (1981-2010) by size
Source of data : INCF (2012)
16Although there are not many written documents regarding large forest fires before the nineteenth century in Portugal, as an example we will mention a few known accounts. Silva and Batalha (1859) mention that the region of the National Wood of Leiria was affected by several fires; Pinto (1939), in his work “O Pinhal do Rei”, describes a forest fire in 1824 which consumed about 5 000 ha in the National Wood of Leiria; and, still in the nineteenth century, 1882 or 1883, there was a fire in the “Matta do Bussaco”, mentioned by Navarro (1884) in his book Quatro dias na serra da Estrela (Four days in the Estrela mountain range).
17In the twentieth century, the 50s and 60s marked the beginning of what would become the seasonal scourge of large forest fires in Portugal (Natário, 1997; Lourenço et al., 2012; Ferreira-Leite et al., in press), resulting from the exodus from the mountain regions and progressive abandonment of forest-related activities, closely connected to the decadence of agricultural activity, which slowly left woods to their own devices. Forests were no longer managed, bush was no longer cleared because it had no use, and firewood was no longer used as a source of energy, leading to the accumulation of biomass in forests.
18The social and economic changes that took place, as well as the consequent shift in habits and customs, provoked a profound change in the relationship between local communities and the surrounding forests. A relationship that was once close, balanced and interconnected slowly ceased to exist, thus paving the way for large forest fires.
19Although fires have always existed in our country, the 1960s are a clear turning point from a healthy coexistence between rural populations and fire to a dramatic reality where fires, as a consequence of lack of territory planning, became a serious threat to forests.
20Thus, the 1960s had a few large forest fires, such as the Vale do Rio/Figueiró dos Vinhos, in 1961 (Lourenço, 2009; Fernandes, 2013), Viana do Castelo, in 1962, Boticas, in 1964, and Sintra, in 1966 (APIF, 2005a).
- 1 1 conto = 1 000 escudos
21Despite these events being mentioned by the National Plan for the Defence of Forests Against Fires (APIF, 2005a), in the case of the Viana fire, for instance, it was only possible to find a written reference by Quintanilha and Moreira da Silva (1965): “Since 1960, in the Forest Grounds, losses have increased at an alarming rate (2 500, 4 000 and 9 500 contos1 that year and the following years) and in 1962 alone in one single fire, in spite of all the efforts, almost 5 000 ha of pine forest were lost and the failure of the response was felt before the proportions of the event became alarming.”
22A similar situation happened upon the gathering of information on the large forest fire of Boticas, in 1964, which proved completely futile. This fact mirrors the little importance that is given to written records that preserve the forest history of the country.
23Regarding the Vale do Rio and Sintra fires the situation is different, as there is some information available, both technical-scientific and media-provided, as well as accounts from those who experienced the event first hand.
24In the fire of Vale do Rio/Figueiró dos Vinhos (1961), the high temperatures in the region, at the end of August of 1961, combined with the economic and social changes that were starting to affect the agro-forest space, contributed to the development of a large forest fire that became memorable for having consumed the villages of Vale do Rio and Casalinho, in the municipality of Figueiró dos Vinhos (Fernandes, 2013).
“At 4 pm on 28th August 1961, a fire of huge proportions broke out and crossed the River Zêzere, and pushed by strong winds it spread in several directions. The fire had a 15-kilometer front, from Atalais, in the municipality of Pedrógão Grande, to the parish of Arega, in the municipality of Figueiró dos Vinhos. It joined another fire that had started near S. Neutel’s mountain range and threatened the town of Figueiró dos Vinhos. In total, 14 settlements of the municipality of Figueiró dos Vinhos were threatened by the flames.” (Unpublished report, sent to the Fire Marshall of the South Region, April 23rd 1963).
25The losses amounted to half a million trees, “two thousand and five hundred hectares of pine forest burned”, two charred villages, Vale do Rio (photo 1) and Casalinho, where “185 people were left homeless” and two dead, “due to asphyxia and fatal burns” (Reporters’ accounts [unidentified] from local newspaper « A Regeneração » - issues no 1025, 1026 and 1030, from 1961).
Photo 1- Rubble of the Vale do Rio village, still steaming, August 30th 1961.
26Five years later, on 6th September 1966, around noon, a forest fire started in the Sintra mountain range and lasted until the 12th. The fire, which alarmed the entire population of Sintra, was spotted by a park ranger, who was the first to inform forest authorities that there was a fire. The flames spread out with the help of high temperatures and constant changes in wind direction. The presence of incandescent components in the air led to new fire fronts across the municipality.
27Sintra was a town taken by fire. The entire region was “surrounded by a huge cloud of smoke – black and thick – visible kilometres away. At night the flames lit up the mountains (photos 2 and 3). More and more fire brigades arrived. The sirens were the screams of the night!” (Diário de Noticias, 10th September of 1966).
Photos 2 and 3 - Day and night photos, respectively, from the Sintra fire, in 1966
Source : Diário de Noticias, September 10th of 1966
28In spite of extreme adverse conditions and lack of means (there were not aircrafts to fight fires, ground crews were not properly equipped and the telecommunications system was rudimentary), fire-fighters and the military defended, successfully, the built heritage of Sintra and prevented the fire from consuming the largest forest area.
29The abundance of dry bush was one of the greatest enemies faced by fire-fighters and, in turn, one of combustion’s greatest friends. At the time, there was a ban on collecting bush in the mountains, which allowed for the accumulation of fuel, a factor that was considered to be crucial in the rapid spread of the fire.
30This was the worst fire the mountains of Sintra have ever seen, 50 square kilometres of burned area, and the most diffused by the mass media, at a time when TV was still black and white but Sintra was very close to Lisbon. Much of the beauty of the mountains was lost, it became a black horizon. The vegetation was considerably damaged. In spite of all these harmful consequences, the scale of this fire was due in great part to the loss of 25 lives, soldiers from the Antiaerial Artillery Regiment from Queluz, who on the night of 7th September were fighting the fire at Alto do Monge, and when the fire was at its peak there were surrounded by flames and died in the fire.
31There have been many human tragedies related to forest fires in Portugal since 1966. Nevertheless, what happened in Sintra is still one of the most painful and dramatic experiences among so many others in our country (Ferreira‑Leite et al., in press).
32Despite these accounts, and until the 1970s, fires were not a crucial problem for Portuguese forests (fig. 2).
Fig. 2 ‑ Annual evolution of the number of occurrences of forest fires and burned area in public areas of mainland Portugal, between 1943 and 1979
Source : Natário (1997) and Lourenço et al. (2012)
33However, after that decade, there was an increase in the accumulation of fuel materials in the forests, as the result of a decrease in sheep grazing and clearing the land for animal bedding, both brought about by the rural exodus started in the 1950s. This state of affairs reflected the socio-economic changes taking place in the southern European countries, particularly in the Mediterranean region at this time (Lourenço, 1991; Vélez, 1993; Moreno et al., 1998; Rego, 2001).
34These changes in the traditional use of land and life style of the populations entailed an increase in the large number of abandoned areas of farmland. On the one hand, this led to the encroachment of vegetation and the increase in the fuel materials accumulated in traditional forest land (Lourenço, 1991; Rego, 1992; García-Ruiz et al., 1996; Roxo et al., 1996). On the other hand, it led to the consequent increase in areas used as forest land. Many of these rural areas became liable to the occurrence of devastating fires as a result of the high quantities of biomass accumulated over the years, which can fuel catastrophic fires during the summer months.
35Consequently, and despite large forest fires having been “trivialised” in Portugal, until the 1980s they had never reached 10 000 ha of burned area in a single occurrence. The first of these fires affected the municipalities of Vila de Rei and Ferreira do Zêzere (Lourenço, 1986) in 1986 (fig. 3) and the second the municipalities of Arganil, Oliveira do Hospital and Pampilhosa da Serra in 1987 (Lourenço, 1988) (fig. 4). We might say that as soon as 1987 a new era of forest fires began in Portugal.
Fig. 3 ‑ Location of the large forest fires occurred in the municipalities of Vila de Rei and Ferreira do Zêzerein, 1986
Source : Oliveira (2008)
36In fact, in1986 the central region witnessed a number of fires over wide areas, of which the one in Vila de Rei should be highlighted. For the first time the formidable barrier of 10 000 ha was overcome, as this fire destroyed over 12 000 ha of forests (Lourenço, 1988) and thus may be considered the first mega-fire occurred in mainland Portugal (Ferreira-Leite et al., 2013).
37In the following year this threshold of 10 000 ha was again surpassed in the central region of Portugal. The forest fire occurred in the municipalities of Arganil, Oliveira do Hospital and Pampilhosa da Serra (fig. 4), between 13th and 20th September 1987 and destroyed about 10 900 ha of forest land and pine trees (Viegas et al., 1988). The fire occurred in a wooded area previously impacted by fires which had transformed partially useable forest land into dense brush land. The rugged terrain and the strong winds that were present during the most dangerous stages of this fire severely conditioned its behaviour.
Fig. 4 ‑ Outline of the location of the fire of 1987, which impacted the municipalities of Arganil, Oliveira do Hospital and Pampilhosa da Serra
Source : Oliveira (2008)
38Among the large forest fires on record, the ones covering the largest area occurred between 2001 and 2010. As mentioned above, it was also at that time that the most extensive area burned was recorded (1 164 748 ha), which means that every occurrence in this decade (with an average burned area of 672 ha) burned more than the fires recorded in the previous decades (in which the burned area reached on average 430 to 440 ha) (fig. 5 and table 2).
Fig. 5 ‑ Burned area per year in mainland Portugal, in LFF, represented in decades, respectively, from 1981 to 2010
Source : ICNF (2012b)
39This was a major consequence of the exceptional character of the year 2003, during which nine LFFs accounted for a burned area in excess of 10 000 ha (mega-fires). These fires were, on the whole, responsible for 138 459 ha of area destroyed by fire (ICNF, 2012) (Table 3 and fig. 6), that is, 29.3% of the total burned area that year.
40It was still in 2003 that occurred one of the two fires in the same period (1981-2012) responsible for a burned area of over 20 000 ha. This meant that 2003 was at the top of the list in terms of burned area (ICNF, 2012). On the other hand, the areas of some fires were contiguous, which meant that the provisional figures made public based on the interpretation of satellite images showed some fires to have destroyed even areas larger (36 019 & 41 079 ha). This was later proved to be the result of more than one fire. Nonetheless, the extension of some burned areas was formidable, as was the case of the Monchique mountain range and the Nisa region, where several mega-fires coalesced and eventually covered an area in excess of 40 000 ha (Table 3 and fig. 6).
Table 3 – Mega-forest fires with a burned area in excess of 10 000 hectares, occurred in 2003. Discrepancies between provisional figures of Divisão de Protecção e Conservação Florestal (DSVPF, 2003) and final figures (ICNF, 2012)
Source of data : DSVPF (2003) and ICNF (2012)
Fig. 6 - Burned area in mega-fires, in mainland Portugal, between 1991 and 2010
Source of data : ICNF, (2012b)
41Although when considered in percentage terms the LFF shows relatively low figures by comparison with the other fire occurrences (<100 ha), the matter of the fact is that they accounted for almost their entirety, more precisely 93% of the burned area that year (fig. 7).
Fig. 7 - Burned area and number of occurrences in 2003, by class of fire size
Source : ICNF (2012)
42As a result, the 2003 balance could not have been worse, since that year alone witnessed 12 of 20 major forest fires on record and 8 of the 10 largest fires occurred in Portugal until that year (Lourenço et al., 2012). Nine of them covered an area in excess of 10 000 ha, which means that they fall under the category of mega-fires (Table 3).
43Among them the fire in Chamusca, in the municipality of Santarém, should be highlighted, because it lent another dimension to the year of 2003. In fact, 17 years after the great forest fire in Vila de Rei had overcome the psychological barrier of 10 000 ha, in 2003, with this fire in Chamusca, another barrier was overcome for the first time which doubled the previous one, and thus represented an area of 20 000 ha of burned area in a single fire (fig. 8).
Fig. 8 - Outline of the burned area of the fire in Chamusca in 2003
Source of data : ICNF (2012b)
44On 2nd August about 11 am, a fire started in the municipality of Chamusca which would prove to be the most devastating forest fire ever occurred in Portugal.
“Four people were killed. Over 20 thousand hectares of forest land [22 190 ha, according to the ICNF database (2012)] and farm land have burned, 20 dwellings have been destroyed, in addition to dozens of small sheds, and 32 people have been left homeless. Two thousand heads of cattle have disappeared, 25 kilometres of phone lines have been destroyed, a manufacturing plant employing 24 people burned to the ground, and the same thing happened to three charcoal plants where more than 20 people worked.” (O Mirante – Semanário Regional, 2003).
45The following year, in 2004, a new critical period of fires started off with large forest fires in July, one of which began on the 24th and impacted the Caldeirão mountain range, in the Algarve, where 14 508 ha of forest land burned (fig. 9). It was the largest fire that year.
46The following year, in 2005, the weather conditions were extremely unfavourable for a period of 18 consecutive days. This was a contributing factor to forest fires, which that year totalled 35 824 occurrences and destroyed 339 089 ha in all municipalities of Portugal (DGRF, 2006).
Fig. 9 ‑ Outline of the burned area in the Caldeirão mountain range in 2004
Source of data : ICNF (2012b)
47One of such ignitions took place on 13th August in the municipality of Pampilhosa da Serra and evolved into a mega-fire that would reduce 11 707 ha of forest land and brush to ashes.
48However, and despite its extent, it was a fire that started a week later, on 20th August 2005, which was given to be the widest ever covered by the media. Although it did not reach 10 000 ha (it destroyed 4 179 ha), it had a great impact as it was the first time that Portugal had seen one of its largest cities in flames within the urban perimeter (fig. 10).
Fig. 10 ‑ Outline of the burned area surrounding the city of Coimbra in 2005
Source of data : ICNF (2012b)
49In fact, the flames closed in on Coimbra during the night (photo 4) and entered the city on the dawn of the 23rd August with devastating intensity. This was the result of numerous incandescent materials being projected, which gave rise to new fires on the front line, and also the low level of humidity of the fuel materials, which stemmed from the prolonged drought. Houses, workshops, cars, facilities and 80% of the Vale de Canas National Forest burned.
Photo 4 – Panoramic view of the flames closing in on the city
of Coimbra on the dawn of 23rd August 2005.
Source : www.bombeiros-portugal.net
50In the far southeast corner of the country, nine years after the occurrence of the first mega-fire affecting in excess of 20 000 ha, and eight years after the mega-fire in the Caldeirão mountain range, the flames returned to these mountains with great intensity, this time in the municipalities of Tavira and São Brás de Alportel (fig. 11).
Fig. 11 - Outline of the burned area in the municipalities of Tavira and São Brás de Alportel in 2012
Source of data : ICNF (2012b).
51The worst forest fire that year occurred between 18th and 22nd July 2012 and was the second largest in the country with a burned area of 21 437 ha, which also happened during a period of extreme dry weather and water levels in the ground below 10%.
52Despite having occurred in brush land (61%) and not having claimed any human lives, this fire forced 351 people to be evacuated and resulted in 25 million Euros worth of damage in the two municipalities affected (Caldeira, 2012).
53To conclude this reference to mega-fires, we would like to mention yet another one. It occurred in the north east of Trás-os-Montes, in the municipality of Alfândega da Fé, in the district of Bragança, and destroyed 14 912 ha of forest, brush and farming land (Table 4) and had an impact on a number of parishes in the municipalities of Alfândega da Fé, Mogadouro, Torre de Moncorvo and Freixo de Espada à Cinta (fig. 12).
TABLE 4 ‑ Distribution of land use in the burned area of Trás-os-Montes in 2013
Source : ICNF (2013)
Fig. 12 ‑ Outline of the burned area in the northeast of Trás-os-Montes in 2013
Source : ICNF (2013).
54The occurrence of this fire may be partly explained by the weather conditions observed in mainland Portugal during the winter/spring and summer months of 2013. March was considered the second rainiest month in Portugal over the past 50 years and snow fell at high altitudes. In the month of May the lowest average temperature over the past 20 years as well as the lowest minimum temperature over the past 30 years were recorded.
55The sequence of occurrences of exceptionally rainy episodes had direct and obvious consequences on the greater development of vegetation. In addition, the first days of July were unusually hot with the low and high air temperatures well above the medium values and close to extreme ones. Their persistence resulted in great temperature discomfort for most of the country. According to the Weather Forecast for the month of July, as of the 3rd a heat wave hit almost the entire country and lasted until the 13th in the Trás-os-Montes region. The conditions that helped prepare the fuel materials for a possible fire had come together.
56It was the largest fire occurred in the region, with extensive damage and severe and lasting consequences at environmental, economic and social levels, in a region where forests play a crucial role in rural development.
57We aim not to explain the occurrence of the LFF, which ultimately depends on a number of varied factors. We simply aimed to present them in a summarised form and characterise them in the context of the current national scene. This was attempted from a historical perspective and given the evolution of the occurrence of large forest fires.
58Although forest fires have always existed in Portugal, they were infrequent. The truth is that the social and economic transformations that have taken place in Portuguese society since the second half of the 20th century have profoundly altered the habits and traditions of the population. The relation between the towns and the forests, which used to be a very close, stable and interconnected one, slowly disappeared and paved the way to the occurrence of extensive forest fires.
59The reality of the LFF in Portugal went through different stages in terms of their extent. As in the 1970s, large forest fires became rather common, but it was only after the 1980s that they reached the status of mega-fires (10 000 ha). Over the following decade, the 1990s, there was an increase in these mega-fires, especially as a result of very particular weather conditions associated with heat waves and prolonged droughts.
60Despite being uncommon, within a 9-year period we have seen two mega-fires covering an area of over 20 000 ha. These fires were characterised by their great complexity with profound and lasting social, economic and environmental consequences. They were in fact more than just large fires, since of all the fires covering extensive areas these two may certainly be considered the most costly, destructive and damaging to the country and the people.