A brief fieldbook addressing the most common questions regarding Wildfires.
-by Cadernos de Campo and Conceição Colaço
Between the end of Spring and the beginning of Autumn, in Portugal, wildfires become a concern, raising several questions, for which we don’t always have answers. Worse, several myths and misconceptions are built around the topic.
For that reason, throughout this field notebook we will attempt to answer 7 frequent questions surrounding wildfires:
In Portugal, does it only burn forest?
No. In the portuguese landscape, besides forests, shrublands and some agricultural areas can also burn. All vegetation can burn, more or less easily, depending on whether it is very dry or very green (with less or more humidity).
Therefore, it’s more correct to say wildfires instead of forest fires.
Are there trees that burn more than others?
Yes. Some species of trees, due to having more oils (eucalyptus) or resins (pines), burn more easily (for being more flammable). Deciduous trees (trees whose leaves fall in Autumn), such as oaks, ash trees and beeches retain more moisture, which makes them less prone to burning.
The place where trees are located may also make a difference.
If they are on a drier zone, for example, on a south-facing slope, they may burn more easily. On the contrary, if they are located in a more humid area, such as near a watercourse, they are less likely to burn.
However, when we have very intense wildfires, like the ones from 2017, unfortunately, these differences become very subtle, since in these situations the fire doesn’t have preference over any kind of vegetation, burning everything that is on its path
Why are there so many wildfires in Portugal?
The dryness of the portuguese climate and the vast amount of vegetation in the forest and shrubland are two of the main reasons on why it happens.
The mediterranean climate consists of rainy winters with mild temperatures, which allow vegetation to grow significantly.
This vegetation then dries out and becomes fuel for fires during the hot dry summers that also characterizes this climate
Another factor is human behavior and practices, because there are no wildfires without something to start them:
– the ignitions.
What is an ignition and how does it happen?
An ignition is a reaction with enough energy to start a fire.
It might be a spark, caused by a train or machine, that lands on very dry fine vegetation.
Or a poorly extinguished campfire where, with the wind, an ember reignites and begins to burn dry vegetation.
It can even be a lightning strike hitting a tree.
Do all trees die with wildfires?
No.
There are actually plants that need fire to reproduce, such as proteas, native to the Cape region in South Africa, which has a Mediterranean climate very similar to ours.
In Portugal, we can also find several plants that have evolved to adapt to and withstand fire.
For example, trees with a protective bark, like the cork of the cork oak, are able to shield themselves from low-intensity fires.
Or the maritime pine, which protects itself in two ways:
– through its bark, which can shield the tree—but only if the fire is not too intense.
– by “using” its pinecones, which open with the heat and release their seeds.
These seeds, called peniscos, have a small wing, and after a fire, once the cone has opened, the seed is carried by the wind and may fall in burned areas. Since these areas have no other plants competing with the penisco, they provide it with a place richer in nutrients to germinate.
Strawberry trees, heathers, and several types of oaks can also survive after a wildfire.
Even though the part above the ground is burned, the root may still be alive.
From the base of the trunk (called the stump), new shoots emerge, which can more easily and quickly grow into a mature tree.
This is why, after a fire, it is important to observe which plants have survived. Since their roots are already well established, they have a better chance of success than newly planted ones.
What is Wildfire Risk?
There are many definitions, and scientists do not always agree.
In general, it is considered to be:
The probability of a fire starting and having the conditions to spread, while also taking into account the elements exposed to the fire (people, houses, forest) and the possible damage they may suffer.
In summary:
- the probability of a fire starting
- and having the conditions to spread, while also taking into account
- the elements exposed to the fire (people, houses, forest)
- and the possible damage they may suffer
For example,
in Summer, an area with a lot of dry vegetation, located in a mountainous region (that is, with a steep slope) and where there is a small settlement, is considered a high-risk zone.
This is both because it contains elements that burn easily and quickly — dry vegetation and steep slopes
and because it includes a settlement (an exposed element), where people’s lives may be in danger.
Is fire a natural event?
Yes.
Fire has existed among us for thousands of years and has been used, since time immemorial, to control wild animals, clear areas, and prepare the soil for agriculture, allowing it to be cultivated.
Fire is a natural element, just like water and air.
The use of fire has helped shape the Portuguese landscape as we know it today.
However, due to the abandonment and depopulation of rural areas, along with long periods of drought, Portugal has suffered from many rural fires — some very severe, causing great damage.
That is why it is essential to learn more about fire so that we can prevent it!
Credits
Texts:
Clear rewriting:
Illustrations:
Design:
Proofreading:
Conceição Colaço
Cristina Soares
João Ruano
Gualtar Amaro
Inês Roque
