A Fire-Adapted Forest

The question everyone who works with forests in Portugal has the unfortunate duty to ask is ‘How will this land burn?’ Not because everything will burn, but because predicting wildfire is imprecise, to say the least, and anything can burn.

Just to get a sense of how dire the situation is, in a recent assessment of the risk of wildfire in Portugal1, it’s been predicted that within the next 10 years there will be a “Black Skies” scenario; a single year in which of the 8 million hectares in Portugal, 750.000 will burn2. That’s about 10% of a country in a single year. While a burn rate of 5% of the country will be normal for the foreseeable future. Keep in mind that ‘normal’ until the 1970’s was about 0,3% a year3.

In the past, when a wildfire would ignite, it would burn a small section of wood or scrub, and quickly burn itself out. Until the 1980’s, a large fire was considered one that burned over 10 hectares, and Portugal had never suffered a single fire greater than 10.000 hectares. But, in 1986, this threshold of 10.000 hectares was passed for the first time, and there has been growing trend of severe fires ever since. Now, most years see single events in which fire extends over 10.000 hectares4. And 2017 set a new record with 11 such fires5.

The historic number of occurrences of Fire in Portugal6

So what’s changed? Why are fires growing in intensity and scope? It’s a complicated answer, but it boils down to there not being enough people to take care of the land. The rise in wildfire is strongly tied to the abandonment of the countryside8. For a few generations now, rural population has been in free-fall with no signs of stopping. People have moved away, either to work in the cities, or to other countries. They’ve left behind their traditional land, and their relationship with the Earth. While those people who’ve stayed behind prefer to work with invasive species like eucalyptus because of how little management is involved as well as the secure income it provides.

Population Decline in Portugal since the 1960s7

The result has been that a decade after the first wide-scale plantation of the eucalyptus in the 60’s the incidence of wildfires began to rise9. Fast forward half a century, and over half of the country’s forested land is eucalyptus or pine10, and 21% is highly flammable scrub-land11.

What’s the Alternative?

So, if we know that the cycle of wildfire is accelerating, and we know it’s because there aren’t enough people to manage the land, what can we do to bring people back to the countryside?

We would argue, that a large part of the solution lies in learning how to manage the land differently. That if we can figure out how to help people earn a living from the woods, while at the same time respectfully managing a strong biodiversity, many people would be inclined to consider learning how. And we might just transform the landscape into one that naturally slows the progression of wildfire.

What makes this both difficult and promising, though, is that the vast majority of land is distributed (more or less) evenly among the millions of Portuguese people, wherever they might live12. And most of the locals who are left are still connected to the traditional idea of the woods being, as my grandpa would call it, ‘The bank of the poor.’ So, since it’s easier to find people with land, then without it, we believe that if they were presented with realistic alternatives to the current monocultures of pine and eucalyptus, their could be a great shift in how the landscape is managed over the next generation.

As of today, no one’s proved to the average landowner that they can make as much money as they do from pine and eucalyptus by planting something biodiverse. And it’s that small but steady income generated every 15 years or so from monocultures (Unless, of course, they burn) that keeps most people planting them.

The most amazing part of this is that when you talk to anyone in Portugal, the vast majority of people will all say the same basic thing which we can summarize in two words. “Eucalyptus. Bad.” It’s widely known that these plantations degrade the ecosystems and cause wildfire, and yet people keep planting them because they don’t quite see any realistic alternatives.

This is one of the main reasons why we’ve been thinking about forests adapted to wildfire. If you could prove that a forest can be both profitable and biodiverse then people would plant it everywhere. And if these scalable forests were designed specifically to decrease the risk of spreading wildfire, then there would be nothing to stop their spread, and lower the incidence of wildfire for the whole country. So, for the rest of this post, we’d like to celebrate our first fire-adapted forest, that does just that.

Forests as a Defense Against Wildfire

If I were to visit the ecosystem best suited to resisting wildfire, I’d either go somewhere where there was almost nothing to burn like a firebreak. Or, I’d go somewhere with lots of water. Somewhere lush with fresh growth, people to care for the environment, ample shade to keep the temperature down, somewhere that spreads its needs for water evenly throughout the year, and keeps the wind at bay. Essentially, I’d be visiting a diverse forest managed by people.

Properly managed and biodiverse forests are much harder to burn than homogeneous landscapes like those composed of monocultures of pine and eucalyptus13. Which isn’t to say that these forests won’t burn – wildfire is an ecologic necessity that will always exist – but if you’ve ever tried starting a campfire with wet wood, you know what we’re talking about.

One of our main goals here is to create mature forests and mature soil that increase the capacity of the ecosystem to hold water 14. This increased water capacity lowers the risk of wildfire15. And that can lengthen the period of time between wildfires. Which, in turn, can lengthen the whole fire cycle, giving us more time to grow stronger, more resilient forests.

Often, wildfire can burn through the same space over and over, which makes it difficult to establish mature forests. A forest designed to slow down and be resilient to wildfire, however, might be able to turn a cycle of fire that occurs every 12 years (like what’s happened to our friend Rui’s land, burning in both 2005 and 2017), into a cycle that takes 20. Then 50. And in time, maybe 500.

Planting a Moat

In autumn of 2019, we decided to reforest a small portion of the land at the southern edge of the land in Silverto. Where the previous owners had left a section of clear-cut field, a weakened soil, and just enough vegetation to pose a serious fire risk, we dreamed about a forest specifically grown to protect against wildfire.

The forest site plan for the moat.

We set out to design a biodiverse forest that resists fire, and at the same time, could earn the people living in Silverto an income through the eventual production and sale of ice-cream using primarily fruit and nuts that they will have grown and cared for.

So, after a few months of research and design, we came to the conclusion (and honestly it took us entirely too long to realize this) that secret to stopping wildfire isn’t in trying to put fires out (though of course it helps). The solution to stopping fires is by maximizing the water in the ecosystem.

So, armed with that knowledge, we decided to build a moat. But instead of digging it down into the ground and filling it with water, we would build it up with soil and fill it in with a forest that serves as a living body of water to protect us. Below you’ll find some of the techniques we use to do just that.

Accelerating Forest Formation

It seems like there’s many places where an invisible clock hangs overhead counting down the time you have to establish the mature ecosystem capable of repelling the next wildfire. The fact is that people can work for years to reforest a space, only to have all of their work disappear in a few minutes. And since it can take decades to establish a mature ecosystem, whatever we can do to accelerate that process, gives us a better chance of surviving that next fire.

For that reason (and many more), we chose to use regenerative agroforestry. Through regenerative agroforestry, we’ll be able to: design the landscape to passively retain rain, increase the diversity of resistant species (which spreads water use out throughout the growing season), accelerate soil formation (which can hold a lot of water), increase moist green growth in the system (which stores and breathes water), produce goods for sale (which increases the management and presence of humans– who strangely enough are also composed mostly of water), protect from winds through hedging and forest structure (to keep moisture in the air), and quickly shade the soil (which slows evaporation).

Once we can do all of this, we shorten the period of time in which there’s an elevated risk of wildfire, which on a larger scale means less fire. This extra water, also means that we extend the growing season by a few weeks or months every year. And this extra growth, in turn, minimizes the time it takes for a space to go from being a young and vulnerable wood, into a mature and resilient forest.

Social Distancing for Forests – Our Fire-Adapted Structure

What’s clear to us is that we want to foster growth. And we want a lot of it. We want to sequester a lot of carbon out of the air, and turn it into productive and beautiful forests. This goal, however, brings with it an inherent risk when it comes to wildfire. The more you grow, the more there is to burn. And no matter how moist our forest is, if a fire on the neighbor’s land catches the right breeze at the wrong time there’s nothing we’d be able to do to stop it. At that point, all we can hope to do is minimize the damage.

But before we move on towards the structure we’ve chosen, it’s important to understand two common plantationstrategies. The first is to plant trees so close together that they push each other to grow straight up. This structure leaves the leaves of every tree in contact. As a result, if a fire passes through an ecosystem like this, it usually stays on the ground, and rushes through. But, sometimes, when the fire is strong enough it can reach up into the crowns of the trees, and the whole forest can go up in a real hellfire.

The second strategy is to spread species wide enough apart so that tractors can pass between the rows in order to turn the soil or clear the understory. This type of landscape lacks shade, leaves soil to be damaged by too much sunlight, and thus makes it hard to build soil and store water in the soil.

We needed a structure that retains the benefits of these common plantation structures (vertical growth and adequate spacing) while limiting some of the risks (crown fire, and weakened ecosystem). All while working with a diversity of species to use light effectively, building soil from within, and retaining as much water as possible. So we’ve landed on the following structure for plantations, which we’re now affectionately calling ‘social distancing for forests.’

This is a cross-section of what our forest might look like in 20 years. You can see that through the strategic placement of paths, a continual discontinuity of heights between the species, and active pruning (as well as composting of the ensuing organic matter), we can keep ample space between species, while at the same time maximizing growth. In much the same way that distance between people, even when they’re in close proximity, can keep the risk of infection down, the distance between species makes it so that the fire has to expend more energy then it receives while it tries jumping between moist leaves. And, since the crowns of the trees aren’t in contact, the forest itself will actively try and bring a crown fire down to the ground where it poses a less serious risk, and where firefighters will have an easier job of putting it out.

Final Thoughts

The reality is that a landscape can burn one too many times and lose the ability to grow back into a forest after a wildfire. This is already happening in the south of the Portugal16, and it seems like the center and north aren’t too far behind. What we’re attempting to create are forests capable of surviving this moment in human history, so that they can stay fertile and outlive us many times over. But this can only happen if the whole region’s culture of land management changes, which happens one piece of land at a time. The truth is that we can’t do anything without help, and in a country on fire, the most important thing to build is community. So, if you’re interested in planting your own forest, helping others to plant theirs, or want to know a bit more, we’d love to talk.


1 Portugal Wildfire Management in a New Era Assessing Fire Risks, Resources and Reforms, 2018

2 For the record, they published a similar report in 2008 in which they predicted that within 10 years there would be a single year in which 500,000 hectares would burn. That year was 2017.

3 Forest fires in continental Portugal Result of profound alterations in society and territorial consequences, 2018

4 Incidence and recurrence of large forest fires in mainland Portugal, 2016

5 Portugal Wildfire Management in a New Era Assessing Fire Risks, Resources and Reforms, 2018

6 Forest fires in continental Portugal Result of profound alterations in society and territorial consequences, 2018

7 Worldbank

8 Analysing how drivers of agricultural land abandonment affect biodiversity and cultural landscapes using case studies from Scandinavia, Iberia and Oceania, 2014

9 Investigacion sobre la historia forestal Portuguesa en los siglos XIX y XX: orientaciones y lagunas. 1999

10 The economic value of Portuguese pine and eucalyptus forests, 2013

11 The economic value of Portuguese pine and eucalyptus forests, 2013

12 Forest Land Ownership Change in Portugal. COST Action FP1201 FACESMAP Country Report, 2015

13 Fire Resilient Landscapes, 2010

14 Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities, 2018

15 Soil Moisture Affects Growing-Season Wildfire Size in the Southern Great Plains, 2015

16 Are drought and wildfires turning Mediterranean cork oak forests into persistent shrublands? 2009

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