Forgotten Forests

Araucariaceae: the ancient giants that are the world’s rarest trees

Finding the few remaining species of a tree family that has survived 200 million years

Araucarias grow in Argentina. Mariano Mantel, Flickr
2 July 2020
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2 July 2020
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This post is also available in: Spanish

This story is part of the Landscape News series Forgotten Forests.

The Scottish-American environmental hero John Muir is famous for his activism to preserve the sequoias of the American West. But in 1911, at the age of 73, he traveled to the other end of the Americas in search of a different forest giant he had only seen in photographs: the araucaria.

In the misty highlands of Southern Brazil, he walked among the distinctive flat-topped conifers for a week, writing in his diary: “Rainy morning. Araucarias in hundreds and thousands. Wondrous sight.” He had recently visited the Amazon, but the araucarias were the trees he’d wanted to see before he died.

It was, he wrote, the most interesting forest he had ever seen.

Brazil’s araucarias belong to an ancient family, the Araucariaceae, which were found worldwide during the Jurassic and Cretaceous periods (200–65 million years ago). Some research suggests their energy-rich, slow-fermenting leaves were a key food source for sauropod dinosaurs.

Now, the family’s three surviving genera are largely confined to the Southern Hemisphere. And like the dinosaurs that once roamed among them, many of these odd-looking trees are now facing extinction.

Within the Araucariaceae family, there are 20 species in the Araucaria genus, including Chile’s monkey-puzzle, the hoop pine of Australia and Papua New Guinea, and the Norfolk Island Pine. Another 22 species belong to the Agathis genus, found in the South Pacific and Southeast Asia, the most famous of which is New Zealand’s colossal kauri tree. And Australia’s Wollemia genus contains just one species, a spectacular ‘living fossil’ only discovered in 1994, with its last stronghold a hidden canyon in a top-secret location near Sydney.

The monkey puzzle, Araucaria Araucana, is so-named for its sharp scales that make its branches difficult to climb. James Gaither, Flickr

A 2018 study ranked the world’s gymnosperm species (non-flowering plants) according to their evolutionary history and extinction risk. Of the top four identified as the highest conservation priority, three were Araucariaceae — the Wollemi pine, Brazil’s araucaria and the kauri. 

A crowded island

Despite the ancient family’s geographical spread, almost half of its living species – 19 out of 45 – are only found on one small Pacific archipelago about 1,000 kilometers from Australia: New Caledonia.

These mountainous tropical islands are home to five Agathis species and 14 Araucaria. “These plants are amazing, they don’t look like anything else,” says Robert Nasi, director general of the Center for International Forestry Research. For research while obtaining his master’s degree, Nasi mapped the distribution of the different Araucariaceae species across the islands.

Some grow only at the very top of New Caledonia’s spine of wet misty mountains, some among broadleaf forest, others on rocky upraised reefs near the shore. “Then you have all the weird ones that look very much like there is a dinosaur waiting behind,” Nasi says. “You’re looking to see what sort of antediluvian monster is going to pop out the other side.”

New Caledonia has been isolated from all other landmasses for at least 45 million years, its geology is complex, and it contains a wide range of ecosystems in a land area of just 18,275 square kilometers — half the size of Switzerland. This has led to a rampant biodiversity, not just among Araucariaceae, but also among plants in general: the archipelago has 3,261 indigenous species – almost as many as the whole of continental Europe – making it the world’s smallest biodiversity hotspot.

The monkey puzzle, Araucaria Araucana, is so-named for its sharp scales that make its branches difficult to climb. James Gaither, Flickr
Araucaria columnaris on the edge of a lagoon on the Isle of Pines in New Caledonia. Tim Waters, Flickr

But with each adapted to a specific environment, New Caledonia’s Araucariaceae are vulnerable. One species, Araucaria scopulorum, is known only from a handful of locations designated for nickel mining, one of the country’s most important industries.

And climate change poses risks for many of the species, too.

“I don’t think they will disappear within our lifetime, but I don’t think they will last very long,” says Nasi. “A species that is restricted to a 200-meter elevation band on top of a mountain on one island in the Pacific probably doesn’t have a bright future under climate change.”

More effort should be put into propagating New Caledonia’s botanical treasures and growing them in living collections, including outside of the country, Nasi says – and the last stands of the most endangered species should be fully protected from mining and other disturbances.   

Fighting fire and pestilence down under

New Zealand’s iconic member of the family, Agathis australis, is facing other threats. Kauri trees can live for more than 2,000 years and grow to be at least 50 meters.  They are considered a taonga, or treasured possession, by the Indigenous Māori.

A vast kauri forest once carpeted the north of the country, but demand for timber and agricultural land after Europeans arrived led to the destruction of 99.5 percent of it by the early 20th century.

Pockets remain in protected areas and on private land. But kauri are now facing a new enemy – a soil-borne fungus-like pathogen named Phytophthora agathidicida, also known as the ‘kauri killer.’

There is no cure, but scientists and Māori are working together, trying to combine microbiology with traditional knowledge in an effort to save the trees.

Australia’s Wollemi pine, Wollemia nobilis, is even rarer, and it might have disappeared from the wild altogether at the end of 2019 if it weren’t for a daring, secret rescue mission.

Until the 1990s, Wollemi-like trees were only known from the ancient pollen record, says Cris Brack, a forestry scientist at the Australian National University in Canberra. “We knew there was something like that tree that had existed. It was all over the continent, and then it disappeared.”

They were thought to have become extinct millions of years ago. Then, in 1994, a park ranger, David Noble, abseiled into a canyon in the Wollemi National Park in the Blue Mountains northwest of Sydney and came across a towering tree he didn’t recognize. It had fern-like leaves and bark covered in chocolate-colored bubbles.

“It was really like finding a living dinosaur,” says Brack.

A young Wollemi pine grows in the Royal Botanic Gardens Sydney. The oldest fossil of the species dates back some 200 million years. Royal Botanic Gardens Sydney, Flickr
A young Wollemi pine grows in the Royal Botanic Gardens Sydney. The oldest fossil of the species dates back some 200 million years. Royal Botanic Gardens Sydney, Flickr

Since then, around 100 Wollemi pines have been found in four groves in the same canyon system, their location kept secret to protect them from vandalism or the accidental introduction of phytophthora.

Genetic analysis has revealed the population has extremely low genetic diversity, making it less resilient to threats.

In an effort to preserve the Wollemi for future generations, horticulturists at the Australian Botanic Garden at Mount Annan devised a way to clone the trees. Since 2006 they have been grown by home gardeners and botanical gardens around Australia and the world.

The Royal Botanic Garden Sydney has just launched an international citizen science project, I Spy a Wollemi Pine, to try to track the different environments the species can grow in.

At the end of 2019, as Australia burned, a record-breaking bushfire started in the Wollemi National Park. It eventually engulfed more than 444,000 hectares, the largest forest fire to start from a single ignition point in Australian history. 

Brack followed its progress and worried it would be the death knell for the Wollemi pine in the wild. “I thought, there’s no way they could have survived that fire.”

But in January, the New South Wales government announced they had saved the trees in a secret rescue mission.

Aircraft dropped water bombs and fire retardant in a ring around the grove. Firefighters were winched into the gorge by helicopter to set up and operate an irrigation system to keep the ground moist.

The world’s largest kauri tree – one of the most species of the Araucariaceae tree family – stands in New Zealand as a sacred site that is known to bring visitors to tears. itravelNZ, Flickr
The world’s largest kauri tree – one of the most species of the Araucariaceae tree family – stands in New Zealand as a sacred site that is known to bring visitors to tears. itravelNZ, Flickr

A few trees were singed and two burned, but the fire passed on and the rest of the population was unharmed.

The effort was worth it, says Brack. Thanks to nursery sales, the Wollemi pine is no longer in danger of disappearing. But many mysteries remain about the species’ genetics and biology, why it was driven almost to extinction, and how this one small stand survived through the millennia.

Those answers might only come from the wild population, and the interactions the trees have with the soil, the climate and the surrounding ecosystem.

“Very few things live in isolation, they live in community,” says Brack.

Brazil’s lost forest

More is known about the Araucaria species that Muir so admired, Brazil’s Araucaria angustifolia. They are the dominant species in a forest type that once stretched 200,000 square kilometers across Brazil’s three southern states – Rio Grande do Sul, Santa Catarina and Parana – as well as part of Argentina’s Misiones province.

Part of the Atlantic forest biome, another global biodiversity hotspot, the araucaria sheltered a hyperdiverse range of endemic palms, shrubs and fruiting trees, including Ilex paraguariensis, the leaves of which are used across southern South America to make the ubiquitous hot drink known as mate (Spanish) or chimarrão (Portuguese).

An Araucaria angustifolia, part of the Araucariaceae family, grows in Brazil’s Parque Nacional de São Joaquim. Mathieu Bertrand Struck, Flickr
An Araucaria angustifolia grows in Brazil’s Parque Nacional de São Joaquim. Mathieu Bertrand Struck, Flickr

The trees provided a crucial food source for birds, mammals and the area’s first Indigenous inhabitants, whom archeologists call the Southern proto-Jê. In the autumn, they harvested the trees’ giant cones full of starchy, nutritious seeds called pinhão. Araucaria still form part of the ritual culture of the surviving Southern Jê,, today’s Indigenous Kaingang and Xokleng-Laklãnõ people.

Recent archeological evidence indicates that around 1,000 years ago, the Southern Jê helped the araucaria forests expand from a smaller natural distribution to cover almost the entire plateau, but it’s not yet understood how or why.

After Brazil’s colonization, humans began to have the opposite effect on the forest, clearing it for timber and making way for agriculture.

At the time Muir visited, in the early 20th century, the sawmills were already whirring. In the 1940s, wood from Brazil’s araucarias was one of the main timbers used to rebuild Europe after World War II, and around 100 million trees were felled between 1930 and 1990. Now, just 3 to 5 percent of the forest’s original extent remains.

Logging araucaria is now illegal. But research in 2019 found that climate change is likely to drive the species even closer to extinction.

Oliver Wilson from the University of Reading and colleagues used modeling to combine climate data with high-resolution topography and vegetation maps. They predicted that by 2070, just 3.5 percent of remnant forest will be suitable for araucaria. They did identify ‘micro-refugia’ – cool, moist areas where the trees might be able to hold on – but found that more than a third of these areas have already been deforested. 

One of history’s most famous naturalists, John Muir, described species of the Araucariaceae family as the most interesting trees he had seen. Goga Park Archives, Flickr
One of history’s most famous naturalists, John Muir, described Araucarias as the most interesting trees he had seen. Goga Park Archives, Flickr

Araucaria have survived significant climate changes before. (They’ve been around for 100 million years, after all.) But while in the past the forests were able to shift up and down the South American continent as the climate fluctuated, they’re now essentially trapped, says Wilson.

“They live at the southernmost extent of Brazil’s southern highlands. They can’t move much further uphill. They’re trapped to the west by deforestation, to the south by low elevations and to the north by changing climates. It’s like climate and human actions together are closing in on them. They’ve got nowhere further to go.”

Still, targeted interventions could ensure its survival in the wild, Wilson says. That could include increasing protection in the most climatically suitable spots, reforestation, and adjusting regulations to encourage landowners to retain and restore araucaria in cattle-grazing landscapes.

We might also be able to discover more about how the Southern Jê managed the forest, Wilson says.  

“If, 1000 years ago, they increased these forests in the face of a climate that wasn’t helping them do so, maybe we can learn lessons to help the forest persist.”


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