Portugal, Greece, Spain, Chile, California and now Hawaii have all battled wildfires this year as high temperatures and strong winds have whipped small sparks into violent infernos.
But fire needs fuel, and what these places also have in common is an invasive species — Australia's eucalyptus tree.
It comes from the oldest continent in the world and it can grow in even the driest of places.
For more than 200 years, seeds of the eucalyptus tree have been planted beyond the bounds of Australia's coastline.
It has been cultivated around the world, making a new home in southern Europe, South America, parts of Africa, the west coast of the United States, and even parts of South-East Asia.
But there is now a debate over whether this tree has been worth the industry and habitat it provides.
Eucalyptus trees mature fast. And in Portugal, as they grew, so too did a lucrative paper industry.
In Chile, rapidly expanding plantations of introduced eucalyptus and pine species feed a $9 billion forestry industry.
In California, the Tasmanian blue gum has become a shady home to birdlife, treasured by some communities, but feared by others.
Because the eucalyptus tree loves fire and fire loves it.
And now, as temperatures across the globe increase and the Earth's relationship with fire continues to distort, there are places where Australia's eucalyptus tree has become a problem.
Exotic souvenir from the south
In the early 1800s, the eucalyptus tree was an exotic specimen from the new southern land, and aristocrats, collectors and botanists alike were eager to plant them in gardens around London and Paris.
The seeds grew at a surprising rate.
The Gardeners Magazine published a "notice of remarkable trees" in 1835, describing how several eucalypts had "sprung to six feet [1.82 metres] from Tasmanian seed planted in 1834", according to Professor Robin Doughty in his published article Not a Koala in Sight: Promotion and Spread of Eucalyptus.
As interest in the new remarkable tree grew across Europe, the benefits of it were being spruiked by enterprising botanists who had sailed south to Australia.
"One indefatigable booster was Ferdinand Jacob Heinrich von Mueller," Doughty wrote.
"This German-born botanist worked steadfastly to establish a reputation for eucalypts."
Von Mueller was the first director of the Melbourne Botanic Gardens and was encouraging the wholesale export for Australian eucalyptus seeds.
By the mid-1800s, there was wide discussion about the uses for eucalyptus trees, as well as their beauty, according to Doughty, and there was a belief that specimens grown from native seeds were best.
Von Mueller would send visiting botanists home with seeds and mail them to other correspondents in his network, always championing the benefits of the tree as he saw them.
He believed "eucalypts would bring about the reforestation of large parts of the Mediterranean world denuded by over cutting", Doughty wrote.
"These amazing trees would supply timber, charcoal, fuel, wood and medicines, as well as draw off standing water and purify the atmosphere."
Von Mueller was the Victorian government botanist for more than 40 years, writing more than 100,000 letters to his network about the flora of Australia.
Through his work, he cultivated an awareness of the eucalyptus and then a global interest in it.
"This collector-scientist orchestrated and sustained the push, bolstering it with scientific authority: he canvassed colleagues and interested individuals, publishers, politicians, and the public in the benefits of this genus," Doughty wrote.
"The eucalyptus symbolised also the hegemony of colonial administrators, who could reach into outposts thousands of miles away and bring back new plants for public approval."
Now, eucalyptus trees have taken hold and there's not much that can stop them.
Australia's treasured gum, the home of koalas and the symbol of the native wilderness at stake every bushfire season, has "gone feral" overseas.
Barbecuing the eucalyptus
Tim Curran grew up in country New South Wales, but he now runs a lab in New Zealand that tests the flammability of plants.
He says the smell of a eucalyptus grove is a nostalgic one that "brings back the memory of home".
But Dr Curran is an ecologist — one who conducts experiments on a literal plant barbecue — and he knows the essential oils that give the eucalyptus tree its sharp, antiseptic-like fragrance are also "highly ignitable".
In their research, Dr Curran and his team barbecued more than 500 plant species and found eucalypts rank in "a category we consider to be moderate to high flammability".
"The first point is that eucalyptus do have inherently flammable foliage," he said.
"The second point, and this is probably the more important one in terms of why eucalypts change fire regimes particularly in other parts of the world, is that they produce a lot of flammable material in the leaf litter layer … known as fine fuels."
Dr Curran said these fine fuels were "easily ignited and quickly consumed" and often helped get fires "off and running".
Ignition, fuel and then the embers — eucalyptus trees can play a role in each stage of fire.
"The other thing that eucalypts do, which helps a wildfire run through a landscape, is that they can cast their burning embers ahead of the fire front," Dr Curran said.
The peeling bark that curls up the side of a gum tree can be swept up to 30 kilometres ahead of a fire.
"All of these things combine to make eucalypt forests particularly flammable parts of the landscape in those environments they've been introduced to," Dr Curran said.
"Then of course we layer on top climate change."
When a region is facing high temperatures, periods of drought, low humidity and even high winds, and a flammable invasive species has increased the fuel load, the role fire can play in the landscape becomes distorted.
"Those are conditions that are going to lead to quite destructive wildfires," Dr Curran said.
'The cane toad equivalent of fire'
The eucalyptus trees are now in places they were perhaps never meant to be.
Because outside of Australia, there are no native or natural enemies to hold them back.
There are no koalas to nest in the fork of their branches, spending hours chewing on their leaves — foliage that's both low in nutrients and high in oils.
The iconically snoozy marsupial spends 20 hours a day just sleeping and digesting.
University of Tasmania fire ecologist David Bowman said there were no other herbivores or any insects that could process the oil of eucalyptus trees because "it's so toxic".
"It's effectively in an evolutionary arms race — eucalypts have invented a whole lot of chemical defences," he said.
Professor Bowman has studied the relationship between fire, landscapes and human life around the world.
He said when walking into a eucalyptus forest in Portugal or Chile there is a moment when "you'd think you're in Australia", but soon enough he notices things aren't quite right.
"They look very different, their crowns are incredibly dense because nothing can eat them," he said.
"So they don't even look much like a eucalyptus tree. They just look like a eucalypt tree on steroids."
Professor Bowman said in some parts of Portugal, the eucalyptus tree had "taken over the landscape".
"They've gone feral," he said.
In fact, the eucalyptus tree is now the dominant invasive species in Portugal, covering up to 9 per cent of the country.
It is believed to have the greatest concentration of eucalyptus trees in all of Europe.
Portugal — regularly among the European nations most affected by wildfire — has spent decades debating the use of eucalyptus trees in its forestry industry.
Professor Bowman said part of the problem was the hereditary system where parcels of land were handed down and divided into smaller and smaller plots, creating a complicated patchwork of plantations that were difficult to manage if landowners moved away.
"Then, of course, you've got the large plantation estates as well, and if they get burnt the eucalypts recover and then they can spread their seeds so they start escaping into the landscape.
"They're sort of like the fire equivalent of cane toads, actually."
Environmental group Quercus has long pushed for the removal of eucalyptus trees across Portugal, and in 1989 members stormed a plantation and did it themselves.
In the local area of Valpacos, 1,000 people pushed past national guard officers and ripped eucalyptus trees from the ground of a commercial estate.
The Quercus campaign continues today.
Just last month, as fires raged in several spots across the country, Quercus again warned about the need to convert areas of eucalyptus plantations into native species.
In Greece, there is a similar movement to remove eucalyptus trees. Spain too.
These landscapes were already prone to fire. Then along came the eucalyptus tree.
Eucalyptus in Chile's 'tormenta de fuego'
The year of 2017 saw the worst wildfire ever recorded in Chile, with hundreds of fires converging to burn more than 5,000 square kilometres of land in what the country came to refer to as "tormenta de fuego" — firestorm.
This year has so far been the second-worst fire season on record.
Professor Bowman walked the fireground of Chile after the 2017 blaze was finally extinguished and published research on what human-environmental factors contributed to its scale and intensity.
"We were able to show that some of the most intense fires were associated with eucalyptus and also pinus plantations," he said.
"The plantations really were driving some of the most intense fires on Earth at that point and these are not non-trivial fires.
"These are absolute raging firestorms."
The regions impacted by tormenta de fuego had been extensively modified by plantations, with less than 20 per cent of the original native vegetation remaining, and extensive presence of highly flammable exotic pine and eucalyptus.
There are approximately 800 species of eucalypts across three main groups — the eucalyptus, the angophora and corymbia.
Almost all are native to Australia, covering more than 100 million hectares.
They have spent millions of years evolving from their rainforest ancestors, adapting to conditions on the continent as drought and fire became increasingly common, and the soil became increasingly depleted of nutrients.
"They're very, very thirsty plants," Dr Bowman said.
"They've got roots that can go down and get a lot of water, and during the summer months they can really dry landscapes out, so you've got this perfect storm."
Von Mueller had hoped the eucalyptus would reforest areas of Europe where native vegetation had been stripped away — and they did. But as they thrived in those environments, they changed them too.
"You're never going to get rid of eucalyptus from California, Portugal, South America, South Africa," Professor Bowman said.
"What we would say, botanically, is they're cosmopolitan. They're everywhere."
In the United States, the Department of Forestry considers several species of eucalyptus to be naturalised in both California and Hawaii, meaning they can regenerate by themselves and have the ability to spread beyond the areas where they were intentionally planted.
Eucalyptus species are present on every island of Hawaii.
Across both states, one of the most dominant species is the Eucalyptus globulus or Tasmanian blue gum, which was introduced to California in 1856 and Hawaii in 1865.
Eucalyptus trees grip the Californian coastline, both in plantations and as windbreaks and sound barriers along the highway.
There is a long-running debate in the state over whether the eucalyptus tree is making landscapes more vulnerable to fire than native trees do in changing climatic conditions.
The point of greatest contention has historically been in the San Francisco Bay area since a 1991 "firestorm" claimed 25 lives.
"For many Californians, eucalypts are a valued part of the natural landscape, while for others they are a nightmare that fuelled the disastrous 1991 Oakland Hills fire," a study into their impacts on the state read.
The challenge for Californian land and fire managers, though, is these trees have escaped into wild areas, altering the landscape and its ecosystems.
Von Mueller's words take on new meaning
The words of von Mueller, the original advocate for eucalyptus trees, take on new meaning alongside the knowledge of how his quest to spread the remarkable tree around the world worked out.
Because while he was promoting the benefits of the eucalyptus and the industry it could create, he was also advocating for the establishment of reserves to protect areas of native forest in Australia.
In Australia's national archive, there is a newspaper clipping that documents a lecture von Mueller gave in 1871 called "Forest Culture in Relation to Industrial Pursuits".
"Strange as it may appear, an impression seems to be prevailing in these communities, as if our forests have to serve no other purposes but to provide wood for our immediate and present wants, be it fuel or timber," von Mueller starts.
"For even after warning of climatic changes, and after the commencing scarcity of wood, no forest administration … has been as yet initiated in any portion of Australia.
He said the wilderness remained "unguarded" and in some places was "already annihilated".
Von Mueller issued a warning.
"No statesman, I feel assured, would want to impoverish our woods at the expense of the next generation."
from Hacker News https://ift.tt/BEUvm8p
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