The Australian tree reshaping the world's wildfires

Each year, more than 400,000 hikers descend on Galicia for the Camino de Santiago pilgrim walk, crossing misty hills and dense green woodland. But much of the forest surrounding the route is no longer native.

Instead of indigenous oak and chestnut, large parts of northwestern Spain are now dominated by eucalyptus.

That transformation is not unique to Galicia. Prized by the pulp and timber industries for its rapid growth and profitability, vast monocultures of the Australian tree have been planted in places such as Brazil, Chile, California, India and South Africa.  

Globally, eucalyptus plantations now cover 22 million hectares across more than 90 countries, and in many regions, they have become a cornerstone of rural economies. But hiding beneath the seemingly tranquil canopies are landscapes vulnerable to extreme wildfires because scientists regard the trees as highly flammable.

European heatwave raises alarms

Europe has already been sweltering this summer, with concerns that the unusually early heat waves could intensify fire risk. Parts of the southern continent have been hit in recent days. Last year was the worst wildfire year on record, with more than 1 million hectares burned — much of it on the Iberian Peninsula. 

Researchers say that while eucalyptus trees aren't to blame for igniting these infernos, they can significantly intensify fires once they start. 

"Eucalypt forests are clearly one of the more flammable forests that we have in the world," Tim Curran of Lincoln University in New Zealand told DW.

"If you put a eucalypt in a new environment, you're very likely to change what we call fire regimes. So things like fire intensity, fire frequency; how hot the fire gets and how often you get fires."

The trees' leaves contain highly flammable oils, and strips of bark can ignite into burning embers. In extreme conditions, those embers can travel huge distances to start secondary fires, as happened during Australia's devastating 2009 Black Saturday fires.

"There was evidence that embers were blown more than 30 kilometers ahead of the fire front to start a new fire," Curran said, adding that it was not a one-off.

In Galicia, plantations can easily outgrow their original borders because while native oak and chestnut can take more than 80 years to reach maturity, eucalyptus needs just 15. As a result, they bounce back quickly when fires decimate landscapes, giving them a competitive advantage over native species.

That creates a self-reinforcing cycle that ultimately allows monocultures to expand further, increasing wildfire risk.

Eucalyptus divides opinions

The plantations in Galicia date back to the 1970s but really took off two decades later. 

In 1992, the regional government released a forestry plan projecting eucalyptus would reach 250,000 hectares by 2030. It took them 30 years to update that plan, during which time eucalyptus ran rampant. 

"It's now around half a million hectares, which is a massive amount of land," local community leader Joam Evans Pim said. 

Though the regional government has since introduced a moratorium on new eucalyptus plantations, campaigners say enforcement remains uneven, and illegal planting persists.

On the one hand, there is money in eucalyptus — the Galician plantations, which predominantly feed the pulp and timber industries, generated €167 million in 2024 alone.

But there is also mismanagement. As younger generations ditch rural lifestyles for urban centers, they are leaving behind uncontrolled plantations.

"[Eucalyptus growth] is happening both because of plantations, many of these plantations being illegal, but also because of land abandonment, because of forest fires, because of the invasive nature of the species. So it's a mix of all these that has led to this result."

What the government did and did not do

Critics accuse regional authorities of failing to control expansion for too long. Luisa Piñeiro, director general of forest management for the Galician government, told DW there had been failures in the past.

"Back then [in the 1990s], there probably wasn't adequate forest management. There wasn't as much control over the plantations or the species being planted," she said. 

Nevertheless, the government does not classify eucalyptus as invasive, and Piñeiro rejects calls for blanket bans. She argues instead for improved management and greater species diversity.

"Rather than banning things, we should first have a forest management plan," she said. "We believe forests should have the species diversity they're meant to have."

Galicia starts to reckon with eucalyptus legacy

Looking over his community's land in Froxán, about 40 kilometers west of Santiago de Compostela, Evans Pim recalls the wildfires that reshaped the surrounding hills.

"This is an area that was affected by a very large fire in 2006. All the woodlands around the village burnt down, and after that it became invaded with eucalyptus," he told DW.

It was when another fire struck ten years later that the community decided to act.  They set up the De-Eucalyptus Brigades volunteer group, working to raise awareness around species like eucalyptus and remove them from community-owned land. What began as a team of 50 people has now grown to1500 operating across Galicia.

"We've been eliminating eucalyptus and allowing native trees to take that space," Evans Pim said. "We want to create a green fire break… and eventually we're aiming to have a land which manages itself. Where we don't have to intervene, and that is resilient to fires and climate change and prolonged drought."

The devastating Portugal wildfires in 2017, in which people died trying to escape, serve as a warning.

"Portugal lived the experience a few years ago; people died, burnt in their cars," he said. "We would really hope we don't have to get there for real change in terms of applying existing laws, and improving all the laws to be taken seriously."

That message is increasingly echoed by scientists, forestry groups and activists who say unmanaged land is becoming one of the biggest fire dangers, not just in Europe but around the world.

Researchers say the economic benefits of eucalyptus increasingly need to be balanced against rising wildfire risks.

"There is a place for eucalyptus, there is a place for the pulp industry, of course," Joaquim Sande Silva of the Polytechnic University of Coimbra said. "But it should be very strict in terms of how you do the plantations and what ecosystems you are replacing."

Edited by: Tamsin Walker