Flammable Trees of Portugal

Last updated on April 17, 2018

Before the fire, our house was surrounded on three sides by the flammable trees of Portugal – lots of very small privately owned plots of mixed Eucalyptus globulus and maritime pine, Pinus pinaster, forming a continuous band of forest intersected a few narrow roads. From the height of many of these trees and the depth of litter, it is obvious they had never been cut or the ground cleaned for decades. We only know how very small the individual plots of land are now because many of the concrete markers have been revealed.

So let’s take a look at the ‘killer’ flammable trees of Portugal which so many blame for the fires of 2017 – the blame mainly falling on the eucalyptus. The maritime pines, which are equally prevalent in Central Portugal and as flammable, if not more flammable, as the eucalyptus, are not subject to the same public vitriol as the eucalyptus – perhaps that’s because they are perceived as non-invasive, native trees.

A few Portuguese forestry statistics

In 2015 the total forest area in Portugal was estimated at 31,820 kilometre² – a steady decrease from the peak of 34,360 kilometre² in 1990.

• 3% of the forest areas are state owned.
• 97% of the forest areas are privately owned, of which…
• 85% are small private forest holdings, 93% of which are less than 10 hectares in area. In north and centre of Portugal most of the forest holdings are less than 0.5 hectares.
• 6% of the forest areas are owned by pulp industries.
• 7% is local community owned.
• Source: EC Europa: Forests, Forestry and Logging 2017

And…

• The area under private ownership is 3,129,000 hectares.
• There are about 400,000 private forest owners in Portugal and 6.5 million of forest holdings.
• From this, 20,700 forest owners (846,137 hectares) are members of forest intervention zones (ZIFs are areas of continuous forest managed under the same forest management plan).
• The pulp and paper industry manages 20% out of the total 23% eucalyptus forest of Portugal.
• Only 40% of Portuguese municipalities and 50% of the national territory (only in the south) is covered by cadastral (land registry) survey. 
• About ¹/₅ of Portugal’s territory is now without any identified ownership.
• In a significant part of the national territory there is no published/official information about who owns the land.
• Note, these forestry ownership estimates have not been updated since 1995!
• Source: COST Action FP1201 FACESMAP Country Report – Portugal (2017)

The total forest areas of Portugal comprise…

• 23% eucalyptus
• 27% maritime pine
• 23% cork oak
• 27% other tree species
• Source: ICNF (2010)

The Flammable Trees of Portugal

Basically all fires need 3 components to start and propagate – fuel, oxygen and heat. The heat component initially comes from whatever ignites the fire (electrical sparks, lightning, lit cigarette end, etc.)  after which heat is self-perpetuating. Break this triangle by taking away any element, there can be no fire.

In the predominately eucalyptus and pine forests of Pinhal Interior Norte and Pinhal Interior Sul of Central Portugal there is obviously plenty of oxygen, but also a super-abundance of super-combustible fuel – on the forest floor, the understorey vegetation and, of course, the dense thickets of trees themselves.

Wherever fuel accumulates in dense forests, exactly like those in Portugal, faster and more intense fires are generated. Fernandes (2009)

On 17 June 2017, the maximum temperature was higher than 40º C, the minimum relative humidity was between 15 and 20% resulting in very low dead fuel moisture content of about 4 to 6% – therefore fire risk was extreme.

How much fuel was there?

In the areas of burnt after the fires of Pedrógão Grande and Góis it was observed…

“…that large areas of eucalyptus had not received any intervention after the first cut and displayed a impressive densities of highly flammable shrubs such as gorse, heather and carqueja. Using national forest data, type of tree cover and contribution to the burnt area, it was concluded the average fuel loads in the forest was 16.3 tonnes per hectare for the Pedrógão Grande fires and 16.5 tonnes per hectare in the Góis fires PLUS the unknown quantity of dead matter, which typically adds 25% to the load. The total amount of approximately 20 tonnes per hectare is above the threshold of an ‘explosive’ fire”.  Comissão Téchnica Independente Report (CTI): Oct 2017 (Emphasis added)

“It is verified that in 69% and 83% of the fire area of Pedrógão Grande and Góis, respectively, the time of accumulation of fuel exceeded 14 years“. Comissão Téchnica Independente Report (CTI): Oct 2017 (emphasis added)

“In the Pinhal Interior Sul region, after the fires of 2003 and 2005, no fires in the following 12 years exceeded burning 1% of the territory. So it is easy to conclude that without significant influence of fuel reduction in pine and eucalyptus, 12 years of accumulation of fuel, in adverse weather, that a fire will gain a great deal of intensity”. Comissão Téchnica Independente Report (CTI): Oct 2017 (emphasis added)

Why does so much fuel accumulate in forests?

Here a distinction must be drawn between the large industrial tree plantations owned by the major pulp companies and the small non-industrialised forest plots of the private owners. In the heated debate about the eucalyptus, the two completely different sectors with totally different forest management / non-management regimes are frequently lumped together. The pulp industry is frequently vilified for having caused all the fires in Portugal with all their ‘killer’ eucalyptus trees, along with the general contempt for the big pulp businesses and predictions of impending desertification of Portugal by ‘plagues’ of invasive trees.

Pulp Companies & Fuel Management

It is obviously in the interest of pulp companies to prioritise and invest in the fuel management of their forests. Among the measures taken to manage forest fuel are manual and mechanical clearance of undergrowth, controlled burning and the use of herbicides, aiming to clean areas of over 10 000 hectares each year. Additionally, pulp companies contribute fire protection and fire-fighting resources and training to the public sector. Source: The Navigator Company

There was only one large area of industrial eucalyptus plantation involved in the June 2017 fire which was within the perimeter of the Góis fire. Information received from The Navigator Company is significant as regards the effects that forest and fuel management can have on a fire of this magnitude:

• 44% of the forest management units within the perimeter of the fire were burnt.
• 20% of the eucalyptus in burnt area was classified as having no damage.
• Fire severity was distributed as follows: 20.6% – reduced, 31.7% – reduced to moderate, 35.1% – moderate to high, 12.6% – high.

Source: Comissão Téchnica Independente Report (CTI): Oct 2017 

Small Private Forest Landowners & Fuel Management

The huge mass of fuel that feeds the forest fires in Portugal, unfortunately comes from the unmanaged or completely abandoned forest plots of the non-industrial private owners. The enormous number of small untended stands of trees form a continuous swathes of eucalyptus and pine forest across the regions of Central Portugal, and elsewhere. The concrete markers indicating ownership and extent of the small plots can be seen now throughout the burnt forests and some plots are no more than a few square metres in size.

Why don’t small owners clean their patches of forest?

There is no clear cut answer as there are nearly as many different reasons as there are owners…

Firstly, you have to look back to the time when rural Portugal depopulated and much agricultural/pastoral land was abandoned. This exodus started in the period following World War II, peaking in the 1960’s and continued steadily. The remaining farmers frequently bought abandoned land and turned it over to forest – eucalyptus, maritime pine (and cork oaks), for an income from the timber and sub-products like resin.

Farmers and their families had to adapt their attitude, skills and machinery to forestry management which is very different from agricultural crops and livestock. However they mostly resided close to the forest and managed the forestry work themselves.

As there are no specific inheritance (or marriage) rules applied to forests, in time the forest plots were divided and fragmented into smaller and smaller units through subsequent generations. This leads to the forested land being frequently owned by urban residents or overseas migrants, who may or may not employ workers to undertake forestry management.

The absentee landowners may also rent their land out where the trees belong to the rent holder and the landowner still owns the land.

So in a nutshell..

• The rural exodus had, and still is having, relevant effects on forest management.
• Decrease in the demand for flammable forest sub-products generated from pine resin = increased risk of forest fires. (Resin tapping yielded an average of 115243 tons / year in the 1980’s decreased to 21326 tons in the period 1996 – 2002).
• The scarcity of workers capable and available to undertake forest maintenance operations increases the labour costs to forest owners, leading to…
• Forest owners are less willing to hire workers to clean their forest holdings, leading to…
• The direct consequence of abandonment of forest land by the owners due to low forest revenues unable to cover the high maintenance costs = increased risk of forest fires.
• Urban lifestyle and the distance the owner’s residence and their forest holding also contributes to abandoned forests, left to regenerate naturally.
• Source: Mendes et al (2004)

In a survey of 2406 non-industrial private forest owners in a cross-section of mainland Portugal, it was found :

Primarily eucalyptus forest owners…

• Do not perform cleaning and stand tending, and the average number of types of silvicultural practices they exhibit is practically zero.
• Harvesting is outsourced to the product’s buyer charged with mobilising the required workforce and equipment.
• The forest establishment results from wild germination and seedlings.
• They correspond to the group of owners who least apply their own or their family’s labour.
• They are the oldest (>70 years of age) owners, with a comparatively higher rate of female ownership (30%), and lower proportion of owners living in the same parish where the forest is located (73%), and having a farm (64%).
• Their properties are very small (<1 ha), small (1 to <5 ha) and medium (5 to <20 ha) sized.
• Forest is viewed as a Property Reserve (54%) where owners do not invest or implement silvicultural practices and forest is viewed as a reserve where harvest timing is mainly decided by criteria other than profitability, OR as an Investment Reserve (25%) where owners invest and harvest themselves but do not carry out silvicultural practices.
• Source: Novais & Canadas (2010)

In the same survey, of primarily maritime pine forest owners…

• The owners carry out silvicultural practices using mainly their own or their family’s labour and equipment, and a clearing saw when it comes to bush cleaning.
• They stand out for the highest number of types of silvicultural practices, about half of the owners performing three, four, or five types of practices.
• However, they do not harvest during the reference period and show the lowest rate of forest establishment.
• They mostly own very small (<1 ha) forest properties.
• These owners are distinguished by a stronger presence of male ownership (80%), with wages from industry and services as chief source of income beyond the forest (18%).
• Owners permanently living in the same civil parish where the forest is located (87%), and daily attendance to it is 83%.
• The forest is seen as a Labour Reserve (59%) where owners carry out silvicultural practices but do not invest in the forest, which is seen as a reserve, OR as a Holding Reserve (26%)  where owners invest and carry out silvicultural practices and tend to view forests as a reserve where they can harvest mainly without profitability criteria.
• Source: Novais & Canadas (2010)

With regard to land use and fuel management within the Pedrógão Grande fire area…

“In most cases there was heterogeneity of land uses due to the fragmentation of properties in small plots, each with different occupations. In five locations there was predominantly agriculture with some forest, while in the rest the predominant forestry; Seven of the sites with forest occupation had the pine tree as the dominant species and seven others had eucalyptus as a dominant species; one of the was predominantly dominated by acacia. Only two of the locations were occupied by a single species (eucalyptus in one case and pine tree in the other). On account of the structure (mainly irregular) and the (mixed) composition of stands and also the traces of undergrowth in a large part of the sites, it is possible to state that a part of the plots either were not managed or were poorly managed, taking into account good silvicultural practices associated to the two dominant species (pinheiro bravo and eucalyptus).”  
Source: Comissão Téchnica Independente Report (CTI): Oct 2017

The Eucalyptus Tree

Eucalyptus is flammable. But the thing that’s most concerning is the volume of material it can produce.”
Scott Stephens, a UC Berkeley fire ecologist.

Portugal’s blue gum eucalyptus (Eucalyptus globulus) was originally introduced from Tasmania in the 1950’s for use in the new paper and pulp industries. Historically, as rural Portugal depopulated with residents moving to cities, the eucalyptus became the ‘crop’ of choice as it was low-maintenance, fast growing and valuable. It is now one of the countries biggest exports. This species has been gradually replacing parts of the pine forests damaged by forest fires, especially in the northern and central regions of Portugal.

Eucalyptus in wildfires

Eucalyptus trees need fire to thrive and, as we have seen just a few days on from the fire, they have pretty much all survived with new growth appearing from the roots and on the trunks.

• The whole eucalyptus tree is full of flammable oil which has the distinct smell commonly used in decongestant products.
• This oil is not only in the trunk, it is in the leaves and long bark strips which peel off and collect on the forest floor or remain suspended on the trees. Essentially, left to its own devices, the eucalyptus stands in a pile of its own debris, ready to burn, and so continue its life-cycle (fire opens the seed pods).
• This debris ignites like gasoline drawing the super hot ground flames into the canopy where the fire may spread on a second high and fast moving front – crown to crown.
• With the atmospheric phenomena that occurred on 17 June, a ‘normal’ forest wildfire can turn into a terrifying, explosive firestorm in minutes where it attains such intensity that it creates and sustains its own wind system, flinging out flaming embers which ignite new fires.
• The steep eucalyptus and pine clad hillsides of Central Portugal further facilitate fire spread…depending on the gradient, the oil-fuelled, wind-driven fires will double or quadruple their speed going uphill, also further increasing the heat intensity.
• In very hot air temperatures, the eucalyptus oil gives off fumes or vapour similar to petrol which can explosively ignite, occasionally blowing the burning crown off to travel through the air to start a new ignition point miles away. In Australia there are records of secondary outbreaks within 20 km of the original fire front.

Eucalyptus after a wildfire

• Depending on the severity of the fire, the eucalyptus re-sprouts readily post-fire even if the tree is destroyed above ground (top-killed). It sends up new shoots from lignotubers (woody growths at ground level or underground) and/or from epicormic buds on the trunk. These epicormic buds are stored deep in the trunk where the bark is thickest. 
• The proportion of pine trees in the eucalyptus stand in a wildfire positively affects mortality and top-kill of the eucalyptus.
• In a managed eucalyptus stands the burned trees are usually cut and the basal re-sprouts may be retained for coppicing.
• The seeds of a eucalyptus are stored in woody capsules in the canopy where they are safer from fire heat damage as ground fire temperatures are higher than those at the canopy. If seed capsules are on the ground in a fire they will burn like everything else.
• The heat of a fire triggers the capsule to split (dehiscence), which allows for germination (in its original region) in the optimal post-fire conditions and when the risk of new fire is low.
• Sources: Catry et al (2013), dos Santos (2015)

Is the eucalyptus to blame for the 2017 fire tragedy?

The answer has to be no. It is the extraordinary level of neglect and mismanagement of the eucalyptus by man that is to blame, allowing the unchecked accumulation of fuel. Man has permitted the unimpeded spread of continuous forests and the ‘double jeopardy’ of these forests composed of mixed flammable eucalyptus and pine, right to the very edges of our roads, houses and villages.

The flammable eucalyptus tree is demonised for many reasons but especially when it comes to wildfires by causing them to spread and burn faster. However, there is not one scrap of empirical scientific evidence that demonstrates this despite all the articles written to the contrary and repeated so often that everyone believes it. 

It has been demonstrated that any unmanaged forest plantation with a high density of undergrowth, brushwood or scrub responds to fire in a similar manner, regardless of the dominant species, compared to the fire behaviour of other plantations with intense management of the understorey vegetation. So, whenever there is eucalyptus, pines or cork oak stands without understorey management, fires can burn for days. Source: Fernandes (2009)

In the book ‘Evolution of Forest Cover in Portugal: From the Miocene to the Present’ by Paulo Mateus & Paulo Fernandes (2014) Chapter: ‘Forest Fires in Portugal: Dynamics, Causes and Policies‘ – based on ICNF data on the land cover of burned areas in Portugal from 1996 to 2012, given a ‘choice’ a fire, by far, ‘prefers’ to burn scrubland over forest. In a forest area however, a fire will avoid Ceratonia siliqua (Carob tree), evergreen oaks and Pinus pinea (Stone pines) in favour of Pinus pinaster (Maritime pine), Eucalyptus globulus and deciduous oaks. Further analysis showed maritime pine stands are more fire prone than all other forest types, including eucalyptus. Moreira et al 2009

This demonstrates another reason why ripping out all eucalyptus and/or pine trees in a fuel management area is not a good idea. If the land reverts to scrub vegetation it is even more likely to burn – less shade on surface fuels, increased wind speeds, reduction of relative humidity, increased fuel temperature and reduced fuel moisture. A case of jumping out of the frying pan into the fire!  Portuguese fuel management law prescribes thinning the eucalyptus and pine trees, not eradicating all of them.

Eucalyptus also gets a lot of stick for using excessive amounts of water, consequently drying out the ecosystem and thereby increasing the wildfire risk. Research from Australia has reported the remarkable finding that all eucalyptus measured across Australia used the same amount of water for a given amount of leaf material – other tree species use various different amounts of water. Estimations of the amount of eucalyptus tree cover at a given location using satellite images of the leaves can help calculate how much water the entire forest or catchment area uses. Zeppel 2013.  Of course controlling eucalyptus water consumption by reducing leaf material would require additional forest management measures, the basics of which are lacking in most areas of Portugal.

Tree Stand Structure & Fire Behaviour

The tree stand structure is more important to fire behaviour than the tree species that comprise the stand. Whether the stand is closed with low or tall trees or whether it is open with low or tall trees is linked to the fuel characteristics and influences wind speed, dead fuel moisture and transition from ground to crown fire. So the fire hazard of dry, flammable tree cover will vary according to the type of management they are subjected to.

Thus, an open stand of low height eucalyptus will increase rate of fire spread far more than an open stand of tall eucalyptus. A closed low stand of eucalyptus is far more likely to create crown fires than a closed tall stand.

This is even more striking with pines…an open or closed low stand of pines will outstrip all other species of tree, even the notorious eucalyptus, for increased fire intensity and crowning. Fernandes (2009)

Trees in the Pedrógão Grande fire

The CTI Report investigated local fire behaviour and its effects by collecting data in a number of different locations in the burnt area, observing burned trees and remaining stalks of shrub vegetation, as well as measurements made on digital cartography. Their observations revealed…

• The dominant fire type in each location was surface fire, but there were six locations where fire burnt tree crowns but did not propagate between the crowns.
• In only two places was the dominant fire type active crown to crown spread.
• Treetop severity was evaluated based on damage to pine and eucalyptus trees.
• The crowns had an average singed proportion of 67% (the remainder corresponds to the canopy consumed) and no pine and eucalyptus trees were observed with green crowns.
• On the contrary, it was possible to observe many cork oaks and other hardwoods with green crowns.
• The fire severity in the trunk of the trees and soil was generally very high based on Ryan (1982) methodology.
• An estimation of the terrain allowed to evaluate the average height of tree trunks at 7.5 m and the minimum diameter of the remaining shrub material (not consumed by fire) 6.2 mm.
• “As a general conclusion we can consider that it was a fire with great severity at the surface, but not at the level of the crowns. These indicators are compatible with information on the existence of very strong and extremely hot winds and surface fuels”.
• Source: CTI Report

Think before you cut all your eucalyptus trees

Eucalyptus globulus trees flower from October to March (in Portugal) and produce abundant pollen and nectar (37- 56 mg of nectar per day), which are massively important to honey bees – not to mention birds and butterflies – particularly to see them through the winter months when most other plants are not in flower.

The world over, honey bees are under threat. They face diminishing habitat and forage resources, attacks by pests and disease, pollution from pesticides and malnutrition, all of which may contribute to the increasing incidence of ‘colony collapse disorder’. For honey bee populations to withstand these stresses, a healthy diet is critical. Of course, we know how vital healthy bees are for the pollination of food crops on which we rely heavily. Across the world, from South Africa to Uruguay and California, bee-keepers and honey producers are utilising the eucalyptus forests, urging for them not to be removed and growing their own eucalyptus stands just for the bees.

In Portugal, where arguably the best honey in the world can be found, the bees have had a terrible time, virtually starving with the extreme drought, high temperatures and then the fires of 2017, leading to an 80% drop in honey production. The bees need need all the help they can get and, by all accounts, eucalyptus honey has many health benefits for humans.

The Maritime Pine Tree

The main pine tree in Portugal is the Maritime Pine or Cluster Pine (Pinus pinaster) which is used in timber production for construction, furniture and poles. The resin is tapped to make rosin and turpentine. The tree originated in the Mediterranean basin and whether it can be called a native to Portugal is still debated by experts but it has grown here for many hundreds of years.

Like the eucalyptus, the pines of Portugal are usually adapted to survive after a wildfire. Where trees are well-managed with forest floor and understorey vegetation clearance, pruning of the canopy and thinning, exposure to moderate fire temperatures can help pines to thrive and they do not present too much of a fire hazard.

However, where good pine forest maintenance is rarely practised, particularly on the small privately owned plots, the pines with their needle, cone and branch debris are a perfect fuel for a wildfire – more so when mixed with eucalyptus.

Maritime pine trees in wildfires

A mature maritime pine can usually survive a low to moderate intensity surface fire because it has thick, fissured bark.

However, a pine rarely survives when it is in the path or head of an exceptionally hot, intense wildfire such as in 2017. Where you see the trunk completely charred from top to bottom, the tree is likely to be dead. Young maritime pines nearly always perish in fierce forest fires as they have thinner bark and not having reached a mature height, they burn as understorey vegetation. As intense wildfires happen more frequently than they did in the past, the pine forests are decreasing in size. In their place there is the progressive substitution of eucalyptus in the region.

• The needles and wood litter of the maritime pine is prone to easy ignition, fast and complete combustion and high heat release.
• The close density of the pines (often mixed with eucalyptus) in unmanaged forests makes for extreme amounts of surface fuel that exacerbates the potential for conflagrations. The canopies are also close or overlapping which facilitates crown-to-crown ignition.
• Like the eucalyptus, pines produce their own volatile compounds (such as α-pinene) which are present in pine needles. These compounds are released when temperatures reach around 150-175 º C. They accumulate locally in the air around the trees and when ignited as the flames reach the area, burn rapidly and intensively possibly causing the phenomena of a fire ‘flash-over’ or explosion.
• Where there are more frequent successive fires in a maritime pine forest area, the trees become even more of a fire hazard because the new young pine trees can never reach maturity and act like understorey shrubs that greatly increase the probability of fire.
• Stands of maritime pine commonly grow on the steep hillsides of Central Portugal so the speed and heat intensity of the fire  increases as it travels uphill and at the crest. This also makes fighting the fire very difficult.
• It must be noted that where stands of pines have been thinned, there will be increased wind movement and litter drying which may aggravate a future ground fire.

Maritime pine trees after a fire

• The pine is partially serotinous and seeds stored in cones in the canopy are the major source for the post-fire regeneration of the tree.
• Cone serotiny (closed cones which require heat to open) may vary among individual trees in the same population – particularly found in the younger trees.
• The serotinous cones of maritime pine begin opening at temperatures around 50º C.
• The cones open gradually in the two or three days that follow the thermal shock such that when seed dispersion begins the fire is extinct and seeds land on a cool bed of ash.
• Adult trees are often killed by fire, depending on the degree of crown and cambium damage, and there is no re-sprouting in the species.
• Typically the burned trees are salvage logged and natural regeneration from seeds occurs.
• Source: Fernandes (2007)

Pine debris left on site after cutting

Where pines have been cut, thinned or pruned, the crown branches with attached needles are frequently left on site which significantly increases the risk of future fires – less shade on surface fuels, increased wind speeds, reduction of relative humidity, increased fuel temperature and reduced fuel moisture. Immediately after the 2017 fires, there was a rush to cut the dead pines before they lost weight and became less valuable, and later cutting to comply with the land cleaning deadlines. In many cases the owners have left vast piles of pine debris which will not decompose any time soon. It can take more than 7 years for pine litter to completely decompose – longer, if there are prolonged spells of dry weather which slow the action of fungi, bacteria and gastropods etc.

In the forests away from human habitation, it may be that the debris is deliberately spread across a cut site in order to mitigate the effects of erosion. This is an common method of erosion control after a fire. However, some experts believe that due to climate change, ‘mega-fire’ events will become more frequent in the near future (Sources: Williams (2013), Mateus & Fernandes (2014)), essentially becoming the new ‘normal’ wildfire. This then makes extensive salvage logging and leaving debris in situ look to be a decidedly dangerous option.

If you have this cutting debris left in your 50 metre (or 100 metre population cluster) fuel management area, you are entitled to request it is removed as clearly prescribed in Decree-Law No. 10/2018 of 14 Fevereiro.

So in summary, miles of continuous, poorly managed flammable trees in Portugal was always a fire disaster waiting to happen…

• Without reducing the fuel load, the resinous maritime pines, in dry conditions, can sustain to fires of great intensity with the possibility of intense ‘flash-overs’ if volatile compounds ignite.
• Eucalyptus under the same conditions, in addition to the greater intensity of the fires, have the characteristic of projecting spot fires at great distances due to easily combustible concentrations of volatile compounds in its leaves.

The CTI report 12 October 2017 (Relatório da Comissão Técnica Independente) observes about the role of the eucalyptus and pine in the Pedrógão Grande and Góis fires…

“It is recognised that pure or mixed stands of wild pine or eucalyptus without effective reduction of undergrowth in situations of drought leads to high intensity fires with the high possibility of projections and secondary outbreaks at great distances. For these two species the rule is that of management of fuel in the sub-forest.”

And with regard forest fire mitigation…

“The best management solutions for the mitigation of forest fires is forest diversification and the use of species that create less fuel formations, in particular deciduous hardwoods, such as oak, chestnut or other hardwoods, because they have a high content of
humidity. These species are not conducive to tree fires and should, therefore, be considered in mixtures with other species or in strategic areas for prevent the spread of fires.”

If we are to continue to safely live close to the pine and eucalyptus forests of Central Portugal, we must create and continually maintain the stipulated fuel management bands and retain and plant as many deciduous trees as possible.

Header Photo: Unknown