Dozens of countries have extraordinary tropical forests, but three stand out: Brazil, Indonesia, and the Democratic Republic of Congo. These countries not only have the largest areas of tropical forest within their borders, they also have the highest rates of deforestation.

We traveled to protected areas deep inside these countries to learn the superpowers of three tree species that play an unusually important part in staving off environmental disaster, not just locally, but globally. These trees play many ecological roles, but most impressive is how they produce rainfall, remove carbon dioxide from the atmosphere, and support hundreds of other species.

If these ecosystems collapse, the climate effects are likely to be irreversible. And so what happens to these forests truly affects all life on Earth.

This is the story of three trees at the center of our climate crisis that provide big benefits to you, me, and the world. Meet the trees, get to know their superpowers, and learn how scientists are trying to protect them.

This project was supported by the Pulitzer Center.

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!COMPONENT:section class=brazil aria-label=The Brazil nut tree, Bertholletia excelsa

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Meet the Amazon’s Rainmaker

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Brazil

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This is the Brazil nut tree, Bertholletia excelsa, an icon of the Amazon rainforest. It’s one of the taller species in South America, reaching the height of a 14-story building.

The Brazil nut tree makes, well, tasty nuts. But its real superpower is channeling an extraordinary amount of water from the soil to the sky, making the rainforest rain.

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A single tree can pump more than 260 gallons (or 3.5 full bathtubs) of water per day up its trunk and through its leaves into the air.

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Brazil nut’s superpower is making it rain

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Here’s how it works:

1 Water in the soil enters through the roots.

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2 The water moves up the trunk.

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3 The leaves release water and particles that help it condense into rain clouds.

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4 The rain falls out of the sky and back onto the forest.

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The Brazil nut tree helps the Amazon rainforest — which extends into eight countries — produce up to half of its own rainfall. (The arrow points to the Uatumã Sustainable Development Reserve, in the heart of the forest, where we visited the Brazil nut tree.)

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This NASA weather simulation shows how rain clouds are constantly bubbling up over the Amazon and moving across the continent. At times, there is more water in the air than in the 4,000-mile river below that gives the region its name.

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The 21 million people of the São Paulo metro area, roughly 1,500 miles from the Amazon, rely on this rainfall for drinking water. Farmers throughout Brazil need it for irrigation.

The Amazon also acts like a massive air conditioner, keeping temperatures down. Climate studies show that when the Amazon is leveled, local temperatures jump by at least 2.5 degrees Fahrenheit on average.

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Here, at the Amazon Tall Tower Observatory, or ATTO, scientists strap on harnesses to study the rainforest way above the treetops.

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ATTO rises 1,066 feet above the forest floor, about the height of New York’s Chrysler Building. The observatory includes three towers; the largest is the tallest structure in South America.

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Here on the tallest tower, scientists measure wind speed and moisture levels. They also track the chemicals fluxing between the trees and the sky that turn the moisture into rain clouds. It can be precarious work.

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Scientists like Delano Campos use the towers like a wide-angle camera lens to get a better read on the rainforest than what can be sensed from the ground.

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From the towers, they can detect signs of deforestation like this in Rondônia, a nearby province. Researchers fear if soy farmers, cattle ranchers, and miners keep destroying the forest, there may be more severe and frequent droughts.

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This green box represents the entire Amazon rainforest. The orange is the 17 percent that’s already been destroyed. With current rates of deforestation, this could hit 25 percent in 15 to 30 years, at which point the Amazon may not make enough rain to sustain itself. The world’s biggest rainforest would then begin an irreversible collapse, eventually turning into dry savanna.

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This looming tipping point is why the surge in forest clear-cutting this year is so worrying. Activists and scientists blame President Jair Bolsonaro, who has shown a complete disregard for conservation since he took office in 2019.

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As more trees are cut down, there will be more frequent droughts, endangering food and water supplies, and livelihoods for millions of people.

That’s why giants like Brazil nut trees are so vitally important. Their ability to produce rain that feeds and cools the rest of the Amazon — and the region — is a true superpower.

By studying these trees, scientists can help predict the irreversible consequences of deforestation. Their work shows those in power the extraordinarily grave risks — to Brazil, South America, and the planet as a whole — of destroying the world’s largest tropical forest.

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!COMPONENT:section class=indonesia aria-label=The mangroves of Indonesia

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Meet Indonesia’s Carbon Guardian

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Indonesia

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!COMPONENT:cinemagraph src=indonesia-fish alt=Drone pans across the roots of the stilt mangrove

This is the stilt mangrove, Rhizophora, a species that dominates parts of Indonesia’s coasts. Every day, the tide rolls in and covers its roots in briny water.

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At low tide, its roots emerge — tall and spindly.

Stilt mangroves do a lot for coastal communities, protecting them from typhoons and tsunamis. Fish depend on them, too: Baby snapper and grouper use them as a nursery, and shrimp use them as a breeding ground.

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But this tree’s most impressive superpower happens underground, where its roots end and the mud begins.

Our current climate crisis is a result of humans putting too much carbon dioxide in the atmosphere. Luckily, trees (and other natural systems) can remove and store some of that carbon. The stilt mangrove is unusually good at this task.

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Stilt mangrove’s superpower is keeping carbon underground

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Here’s how it works:

1 The tree absorbs carbon from the atmosphere and uses it to grow its trunk, leaves, and stems.

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2 The carbon-rich plant material eventually falls off the tree and ends up in the soil.

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3 In the wet soil under the roots, the carbon can’t return to the atmosphere because it’s sealed off from the air. It can remain there for millennia.

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These orange lines don’t look like much, but Indonesia has 23 percent of all the mangrove areas on Earth — covering 7.1 million acres, the size of Belgium. (The arrow points to Tanjung Batu, East Kalimantan, where we visited the stilt mangrove.)

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Rainforests get a lot of credit for being carbon sinks. But scientists have discovered that an acre of mangroves can store five to 10 times as much carbon as an acre of rainforest.

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The stilt mangrove isn’t just storing carbon above ground, but also in the soil, up to 10 feet down. There, as “blue carbon,” it’s an underground vault, secure for millennia, as long as it’s sealed off from the air.

This ability to both remove carbon and keep huge stores of it protected is a tremendous asset in the climate crisis. It’s why preserving and restoring mangroves is being hailed as a promising “negative emissions technology.”

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Here’s a palm oil refinery in East Kalimantan on the Indonesian island of Borneo. Over the past three decades, Indonesia has lost 40 percent of its mangroves to palm oil plantations, shrimp farms exporting to the US and China, and pollution.

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Indonesian scientists like Novi Susetyo Adi are racing to measure the carbon in mangroves to show the government this ecosystem’s enormous potential for fighting climate change.

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He and a team of scientists from the Ministry of Fisheries and Marine Affairs, with partners from Japan, are in East Kalimantan to take samples from the trees and soil. But because Indonesia’s mangroves are spread over thousands of islands, research and protection are an immense challenge.

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When mangroves are cut down, the soil beneath the trees is exposed to air and starts producing greenhouse gases. This ecosystem is terrific at storing carbon, but there’s a dangerous flipside when it’s disturbed.

Since Indonesia’s mangroves hold the largest blue carbon stocks in the world, many scientists are calling for stricter laws against deforestation here. Mangrove destruction will only accelerate the climate crisis and doom the hundreds of millions of people in Indonesia’s coastal communities to worsening sea-level rise and dying fishing areas.

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!COMPONENT:section class=congo aria-label=The strong Afrormosia of Central Africa

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Meet Congo’s Forest Caretaker

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Congo

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With its leopard-print bark and towering pencil-straight trunk, the Afrormosia or African teak tree (Pericopsis elata) cuts a stunning figure in the Congo Basin rainforest. This is the second-largest rainforest on Earth, and like the Amazon and Indonesia’s coasts, it plays a crucial role in regulating rainfall and storing carbon. But this rainforest is the least studied and most overlooked.

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The Congo Basin stretches into six countries in Central and West Africa. It’s a place of staggering, exuberant biodiversity. Here, a mother and baby Grauer’s gorilla, a critically endangered species, climb through the forest in the Kahuzi-Biega National Park in the Democratic Republic of Congo.

A wide, tall tree with dense wood, Afrormosia is an important carbon sink in the Congo Basin rainforest. But its superpower is its resilience and ability to support other species — and the entire ecosystem — around it.

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Afrormosia’s superpower is being a forest caretaker

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Here’s how it works:

1 When food is scarce, birds and monkeys can feast on Afrormosia’s unripe seed pods.

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2 Its leafy canopy provides shade for plant and animal species on the ground.

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3 Its flame-resistant bark can weather natural and man-made fires, allowing the tree to help other species recover.

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The dark green area is where the only major population of Afrormosia remains. The shaded area is where it was found as of 1950. Since then, the tree has all but gone extinct in Ivory Coast, Nigeria, and Cameroon. (The arrow points to the Yangambi Biosphere Reserve, where we visited Afrormosia.)

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A key reason Afrormosia survives in Congo is the country is virtually landlocked and has poor infrastructure. Violence has also slowed the country’s development. And even here, the tree is not safe.

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Demand for Afrormosia’s yellowish-brown wood continues to be high, in Africa and beyond. Yacht builders and floor makers prize its consistent texture and resistance to decay.

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Many people in this developing region rely on selling Afrormosia’s high-value timber for their livelihood. Managing the species — so that the forest remains resilient and people can continue to use the wood — is the key to its survival.

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A team of Central and West African scientists at Yangambi Research Station on the Congo River is trying to find new ways to help the tree thrive. Currently, Afrormosia takes several decades to reach maturity, and it’s not easy to make it grow faster.

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Afrormosia needs a lot of light to grow. It waits patiently until a tall tree falls or is logged, creating an opening in the canopy above. Then it races upward.

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Scientists still have much to learn about this species. Here, Chadrack Kafuti measures a tree’s growth rate and captures the data on his laptop.

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Back in the lab, Kafuti uses a microscope to look at a tree sample. He’s studying how Afrormosia’s growth rate responds to light, drought, logging, and climate change in different forests.

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This room full of samples could help the Yangambi researchers figure out the ideal conditions for Afrormosia to thrive. They’re worried that if too many trees are logged, it will threaten the resilience of the entire forest ecosystem.

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At an Afrormosia nursery, Hulda Hatakiwe nurtures hundreds of seedlings and saplings. One day, she hopes farmers will cultivate the tree, too.

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But it’s a race against time as loggers — both legal and illegal — reach deeper into the forest to satisfy the insatiable market for this wood in the US, Europe, and China.

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There is an alternative: purchasing only sustainably harvested Afrormosia under the rules of the Convention on International Trade of Endangered Species, or CITES. The international community can also support Congo’s government in punishing illegal loggers.

If Afrormosia goes extinct, it could threaten the forest’s resilience and stability, increasing greenhouse gas emissions, and unleashing more chaotic weather on Africa and the rest of the world. It’s in everyone’s interest to protect these trees.

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Brazil nut, stilt mangrove, and Afrormosia are just three species in three wildly diverse and important ecosystems. But they all make remarkable contributions to the communities around them — and to those of us continents away. As new science has revealed, we are much more dependent on these parts of the world than we might think.

When it comes to the crises of global warming, extreme weather, and biodiversity loss, it really does matter if the Amazon reaches the tipping point, if a stretch of Bornean mangrove gets razed to build a shrimp farm, or if a tall yellow giant in Congo goes extinct. It’s not just losing a pretty tree 12,000 miles away — it’s cascading ecosystem collapse with long-range effects. We may not feel those effects yet, but we will feel them in our lifetimes. ️

Want to help? Read Vox’s piece on six high-impact organizations working to fight climate change.

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Credits

Reporters:
Eliza Barclay (introduction and Indonesia)
Umair Irfan (Brazil)
Tristan McConnell (Congo)

Photographers:
Victor Moriyama (Brazil)
Ardiles Rante (Indonesia)
Sarah Waiswa (Congo)

Editors:
Ben Pauker
Eliza Barclay
Susannah Locke

Visuals editor:
Kainaz Amaria

Design and graphics:
Amanda Northrop
Ryan Mark

Developer:
Ryan Mark

Copy editor:
Tim Williams

Engagement:
Alexa Lee
Nisha Chittal

Video editor:
Madeline Marshall
This project was supported by the Pulitzer Center.

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YANGAMBI RESEARCH STATION, Democratic Republic of Congo — A pair of 70 horsepower outboard motors cut the river journey westward, from the city of Kisangani, to just two hours. By the more common motorized barges — floating cities in their own right, bursting with commerce and chaos — the journey is four times longer. The even more common canoes, poled and paddled by hand, stretch the trip into days. The alternative is a rutted dirt road so extravagantly potholed and seasonally impassable that it is mostly, and sensibly, avoided. 

Congolese infrastructure is scant and parlous, a daily losing battle against neglect and nature. But even so, the Yangambi Research Station in the heart of the world’s second-largest rainforest is remote from everywhere.

Not far downriver from Kisangani’s city limits, concrete and brick houses give way to thatched huts and, soon after, to the forest. Soon there is no riverbank at all: trees and a kind of rainforest creeper, called liana, cascade directly into Congo. The forest is an endless undulating green wall, but “green” does no justice to the tropical palette: fern, laurel, lime, moss, teal, emerald, neon. 

When we reach Yangambi, a long, squat three-story brick building set back from the river’s edge, silhouetted against the trees, greets visitors. There are gaping holes in the roof and missing panes in the window frames. Adjacent is an abandoned rubber factory and, next to that, derelict gas storage tanks. Half a century ago, before the Belgian colonialists left, this was a world-leading research center with all those things and more. Today, there is no electricity here, no paved roads, no piped water.

But before the research station was entirely reclaimed by the forest, a new generation of mostly African scientists made it their home. They work in these remote, arduous conditions running a range of experiments, including how to breed disease-resistant bananas. But one of the most urgent projects is to understand how an ecologically critical and economically valuable indigenous hardwood tree species can be helped to reproduce better and grow faster. 

Tropical forests cover up to 10 percent of the land on Earth; the global climate system depends on them for rainfall and carbon sequestration and storage. They also support some of the world’s most incredible biodiversity. The Congo Basin, stretching across six countries, is home to the second-largest rainforest on Earth. Forests cover two-thirds of the DRC, sub-Saharan Africa’s largest nation, roughly the size of Texas and Alaska combined. But they are being felled rapidly. In 2018, the DRC lost the second-largest area of tropical primary forest of any country (after Brazil), according to Global Forest Watch data.

Without the Yangambi scientists’ research, logging could doom one remarkable tree species to extinction.

A uniquely charismatic member of Africa’s crowded society of trees

To some it is called the “queen of the forest,” to others the “leopard”; still others know it as “African teak.” 

For Brice Djiofack, a Cameroonian bioengineer who spends his days in the dank understory, far below the thick canopy, it is Pericopsis elata or Afrormosia. To Dieumerci Kibinda, a Congolese botanist, it is, simply, “the most beautiful tree.” Its dappled bark glows silver in the shade and burns auburn in the sun; its spreading upper branches breach the canopy, the delicate tapering leaves of its crown reach toward the sky.

Afrormosia is a uniquely charismatic member of the crowded society of trees in Africa’s vast green heart. As a large, canopy-topping species, it is an indicator of — and key contributor to — the health and diversity of the forest ecosystem. Its soaring crown provides shade and shelter to understory plants; its ripening seed pods are food for birds and monkeys; its seeds are meals for beetles, and its flowers homes for butterflies. Its fire-resistant bark means it survives when other trees succumb to natural or man-made conflagrations, making it a pioneer in the recovery of fire-scoured landscapes; below ground, its deep nitrogen-fixing roots suck nutrients up into the soil.

Where Afrormosia trees are found, they create “islands of their own typical forest,” says Nils Bourland, a forester at Belgium’s Royal Museum for Central Africa who helps coordinate research on the tree at Yangambi.

Over a centuries-long life, the tree transforms atmospheric carbon into incredibly dense hardwood, helping sequester greenhouse gases. The oldest Afrormosia ever encountered by Bourland was perhaps 400 years old. And yet, for a giant, an Afrormosia rarely exceeds 1.8 meters in diameter, giving it the dimensions of a pencil.

Even in death, it provides. Its lumber is a source of desperately needed income for the poor Congo nation. Strong, stable, easy to process, durable and attractive, Afrormosia has been sought after for shipbuilding, flooring, French windows, staircases, paneling, and cabinets.

A 1969 book of world timber describes Afrormosia as “high quality … with an attractive appearance resembling a fine grained teak … but without the latter’s oily nature. The heartwood is yellowish-brown. … Unlike teak it does not bleach on exposure to the weather, but tends to darken with time.”

But Afrormosia cannot be easily felled. Its interior is rock hard — I watched scientists sweat as they struggled, sometimes unsuccessfully, to extract cores as slender as swizzle straws using a hollow-pointed hand drill. Felling it with a handsaw or ax requires strength, tenacity, and lots of time.

Until a couple of human generations ago, Afrormosia was widespread in West and Central Africa. Ivory Coast was full of it — from Liberia in the west all the way to the eastern border with Ghana. Its populations were a mainstay of the forests of Nigeria, Cameroon, and the Republic of Congo. Ghana shipped the first Afrormosia to world markets in 1948 and thereafter exploitation was rapid, and quickly unsustainable. 

Just a few decades of breakneck, mechanized logging was catastrophic; by 1992, Afrormosia was added to the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or CITES, a list of species that face extinction should their trade not be adequately regulated. Six years later it was placed on the International Union for Conservation of Nature, or IUCN, Red List of endangered species, the official global tally of plants and animals threatened by extinction. Today it can no longer be found in Ivory Coast at all, and only small pockets survive in its other former territories — except for Congo, where the last major stand persists, but is under threat.

Afrormosia is also, unhappily, a hard tree to regenerate. It is slow growing and requires a great deal of light — a scarce resource in thick forest. To survive, it has developed a novel and unusual technique for managing its growth: racing upwards and outwards when light is plentiful and pausing, almost in stasis, when it is not. As a result, its cylindrical trunk’s thickness is no guarantee of age: a skinny sapling may be many decades old, existing in suspended animation, waiting for a break in the canopy. 

Because the tree appears to benefit from at least some disruption in the environment, Afrormosia is a totem of survival and coexistence, even with the humans that threaten its survival. This growth spurt might occur when another tree is struck by lightning or blown over by the wind, as occasionally happens, tearing a hole in the forest roof and allowing the light to flood in. It might occur when humans chop down a fraction of a hectare of forest to grow crops, found a village, or clear an area to cultivate a particular species of tree. But wherever an opening is made in the canopy, Afrormosia seizes the opportunity to thrive.  

Slash-and-burn farming over tens of thousands of years of human habitation in Central Africa makes a nonsense of the notion of a pristine African Eden, a zone of forested wilderness. The question is not how to fence off and protect what remains of Africa’s tropical forests, but how to carefully manage them as human populations grow and economic demands for space and resources increases.  

The choice governments and loggers make now is fundamental: People can continue to exploit Afrormosia as we are and drive it to extinction, or, through sustainable forest management, ensure its survival. “It’s on us,” says Bourland.

African scientists are transforming a history of colonial exploitation into domestic conservation

Yangambi was once a prestigious international center for the study of trees. During the first half of the 20th century, Belgian colonialists built roads, houses, a pavilion restaurant overlooking the Congo River, a swimming pool, and a 300-seat cinema and theatre. Much is now in ruins.

The large post office that greets visitors who arrive by river hasn’t received mail in years; its basement is a lot for abandoned vintage vehicles and other rusting machinery. There is no electricity to light the broken street lamps, the red brick roads have worn away, and forest has reclaimed pavements, walls, and buildings.

But the efforts of a handful of mostly young African scientists are slowly transforming a history of colonial exploitation into a story of domestic conservation. 

The foreign researchers abandoned Yangambi at independence nearly 60 years ago, leaving not a single trained Congolese scientist behind. Decades of neglect, underfunding, corruption, and elliptical conflict followed. The old research findings were either whisked back to Europe or left to rot in Yangambi’s library and herbaria.

Elasi Ramazani, a trim, soft-spoken 65-year-old in spectacles and a striped shirt, has worked at Congo’s National Herbarium for over three decades and is its current director. In the collection room, floor-to-ceiling steel cabinets contain 150,000 leaves and grasses (there were fruits too, once, but they rotted away). “All the biodiversity of the Congo is here,” he says.

Among the bound sheaves is an uprooted tussock, yanked from the earth by King Leopold III himself in 1957 — three years before Belgium relinquished its claim to Congo — squashed flat and taped to a sheet of paper.

The colonial experience was particularly rapacious in Congo, which was treated as nothing more than a source of valuable resources and an expendable slave labor force. When Ramazani earned his botany degree from Kisangani university in the 1980s, he was among the first Congolese scientists. “When the Belgians left, they said they had collected 60 percent of the plant species in Congo, we are here to collect the remainder,” he says.

“They did good research during the colonial period but they did it for themselves,” says Chadrack Kafuti, a 27-year-old Congolese forester pursuing his PhD at the University of Ghent in Belgium.

The scientists are part of a Yangambi-focused project known as FORETS, in its French acronym (Training, Research, Environment in Tshopo in English) led by the Center for International Forestry Research (CIFOR) and funded by the European Union.

In his prefab lab, Kafuti works alongside Nestor Luambua, a 29-year-old dendrochronologist completing his PhD, and Sorel Wasukundi, 27, a second-year biodiversity management student, both of whom are studying at the University of Kisangani. They work long days and through weekends, using microscopes to assess samples they collect by hand from the forest during days- and weeks-long expeditions. The goal is to understand how Afrormosia responds to light, drought, logging, and climate change, in both managed and protected forests. 

Three-quarters of a century ago, foreign researchers had unusual success in propagating the tree in Yangambi, seeding saplings alongside mother trees in remarkable numbers not seen in the wild.

As part of his recent master’s thesis at Université Catholique de Louvain in Belgium, Djiofack, the 32-year-old Cameroonian scientist, uncovered a crumbling map that he uses to guide him around a patch of forest unusually replete with Afrormosia.

“The demarcation of this area is still from colonial times,” he says, walking through an area where the trees abound in various heights, widths, and ages. “It is only here that you can find this kind of regeneration of Afrormosia in the world; this is why we are trying here to find, what are the good techniques? What have they made to have this successful regeneration?”

Over the years, different management strategies for Afrormosia have been tested here. The intervening years of neglect have rendered the forest in time-lapse, making visible the varied outcomes of those strategies: in some of the one-hectare squares marked on Djiofack’s desiccated map, Afrormosia thrives; in others, none remain. Some techniques work and some don’t, that much is clear, but with the map’s legend missing and the original researchers long dead, Djiofack is working to interpret the results. “It’s step-by-step,” he says, plunging deeper into the dense, soaring forest.

The hands-on, sweaty science of learning Afrormosia’s limits and potential

The knowledge about what makes Afrormosia survive and thrive holds the dual promise of sustainable management: effective conservation to keep the species alive, and managed exploitation to keep the economy alive. The two are intertwined.

Without that knowledge, both are doomed, making the meticulous work of Djiofack, Kafuti, Luambua, Wasukundi, and others essential to the forest, Congo, the tree, and the planet. A crucial element in the exuberant biodiversity of the world’s second largest jungle, Afrormosia is an indicator species, signaling the health of its ecosystem. But its resilience and value is only now being discovered by this determined team of mostly young African scientists at Yangambi.

According to its CITES listing, Afrormosia may only be exported with a permit, and technically, permits should only be issued if the logging will not degrade the sustainability of the population. But without rigorous research it is impossible to quantify how much Afrormosia of what size you can take out before pushing the population off a cliff. Meanwhile, Congo’s endemic corruption and lax application of laws means the entire extractive sector — whether timber or minerals — is prone to illegal exploitation.

“Afrormosia is a species that is important and endangered in Congo and West Africa,” says Wasukundi, who is studying leaves to determine how Afrormosia copes with a gradually drying climate.

Luambua looks at a bigger picture of disruption, seeking to understand the cause and age of disturbances in the canopy, to map the forest’s dynamism and Afrormosia’s role within it. “I want to know, was the forest destroyed by man or climate?” he says. 

To find out he spends weeks at a time fording streams, bushwhacking through dense foliage, pitching camp and fending off insects, then cutting transects, surveying trees, extracting samples and measuring trunks. Afrormosia is like a history book, its clustered presence indicating a past disturbance. Afrormosia, he finds, “will congregate in places that were open in the past,” where space was available and light flooded in.

These discoveries are contributing toward a template for forest management that might ensure the coexistence of tree and community. 

In the patch of forest he studies, Djiofack steps lightly through the undergrowth, knapsack on his back, talking and gesticulating as he passes trees painted with rings, daubed with codes, and hung with dog tags identifying them as part of the project researching Afrormosia’s powers of regeneration, propagation, and growth.

The results will help to accurately determine the minimum diameter for sustainable exploitation, a figure that currently rests on guesswork. “A little information can have a high impact,” he says, slapping the brittle bark of a thick Afrormosia.

It is hands-on, hardworking, sweaty science in this place. Early one morning, Kafuti, Luambua, and Kibinda — the botanist and Yangambi’s most respected forester — head into the green through clouds of butterflies and shimmering streamers of cobwebs to check readings and collect samples. They stride into the forest, armed with the tools of their fieldwork: machetes and measuring tapes, hand drills and handheld GPS, Ziplocs and laser rangefinders.

An hour in, Kafuti has attached sensors called dendrometers to two-dozen Afrormosia, measuring their growth at 30-minute intervals. Plugging his laptop into one reveals a graph of daily minimum and maximum growth rates that resembles the spiky readings of a human breathing monitor as the tree responds, in millionths of a meter, to environmental changes. 

The results will be correlated with climatic data on humidity, rainfall, and air temperature as Kafuti seeks to understand and bolster the tree’s resilience.

All of this new understanding also feeds into an Afrormosia nursery, a bumpy half-hour drive along cratered roads outside Kisangani where Hulda Hatakiwe, a 26-year-old Congolese forestry engineer working for CIFOR, is nurturing hundreds of seedlings and saplings. Here, at the world’s only Afrormosia nursery, she is hoping to determine what conditions the tree likes and whether it can be effectively cultivated.

In a pair of adjacent circular plantations, Hatakiwe manages over 400 saplings, some already taller than she. The young trees have been planted in clusters at the center and are more spread out toward the edges. “The methodology is to test if they grow together. In the end, we will be able to say what is the best distance between trees for planting Afrormosia,” she says.

This, then, might be Afrormosia’s sustainable future: Populations of trees large enough to withstand controlled logging, and successful enough at regenerating to quickly replace those lost. In a modern era of population growth and spiraling demand for resources, successful cultivation for commercial exploitation and restorative conservation might harness and multiply Afrormosia’s remarkable resilience.

Unprecedented threats to Afrormosia and the Congo rainforest put the tree at great risk of extinction

People and trees have coexisted in Congo for as long as humans have lived there, but a booming population and greed are upsetting the long-standing, delicate ecological balance, and bringing unprecedented threats to Afrormosia and the Congo forest.

Demand for Afrormosia has traditionally come from Europe, China, and, to a small degree, the US. But in recent years, the dynamics have shifted as a domestic and regional market has developed, especially in nearby countries such as Kenya, Rwanda, and Uganda. They are all reachable by road and function under less strict CITES scrutiny, due to corruption and loose border controls.

Excessive industrial logging for the international market has been reduced thanks to stricter enforcement of stronger laws, but smaller-scale illegal logging is rising to meet the demand of the increasingly wealthy domestic and regional consumers, a trade that is “absolutely unregulated,” says the forester Bourland. Congolese national data shows legal exports of around 20,000 cubic meters (or roughly 1,000 trees) of Afrormosia annually, mostly as raw logs, but the illegal exports are, by their nature, not accounted for and the size of the illicit trade is unknown.

“This is really new and something that is a concern for us,” he says. “We have been focusing on exports to China, to Europe, to other continents, but if we look at the regional market it could be the impact is much, much stronger.”

On top of that is a more homegrown threat: the gradual but persistent cutting down of trees for fuel and clearing space for cultivation or artisanal mining, small individual incursions that add up to a collective assault. The forest might absorb the demands of a village of hundreds, but what happens when that village becomes a town, or a city of millions? Every year, Kisangani’s footprint expands, squeezing the forest from the periphery, while small mining camps inside the forest grow like a cancer whenever a rich seam of alluvial gold or diamonds is discovered, eating it from within.

On a recent morning, the forest was preternaturally quiet, footsteps dampened by windfall and undergrowth, voices absorbed by bark and leaves. But the depth of the silence was unnerving: Where were all the animals?

One answer could be found in the Sunday market at Yangambi village. Cane rats, hammer-headed bats, monkeys, and small bucks — all smoked and trussed — crowded the bushmeat stalls alongside edible caterpillars and dried fish.

Congo’s population was an estimated 15 million at the time of independence; today it is around 86 million, three-fifths of whom live outside of urban areas and three-quarters of whom live in what the World Bank defines as “extreme poverty,” meaning they get by on less than $1.90 a day. Those dire statistics are a direct result of the corruption and the conflict that has defined the country under the kleptocratic rules of Presidents Mobutu Sese Seko and then Laurent and Joseph Kabila.

For many living on the river’s banks and in its mushrooming riparian towns, bushmeat is the protein of choice, leaving forests within hunting range of the river eerily quiet. During butterfly season, the main rutted track into the forest from Yangambi village becomes a commuter artery, everyone in search of something: children collecting edible caterpillars, women foraging for greens, men hunting for bushmeat. And everyone collects firewood.

Few human activities are more destructive than the manufacture of charcoal, or makala as it is known in the Lingala language. Afrormosia’s density makes it attractive to the charcoal manufacturers, but thankfully it also makes it hard to chop down. While the trade does not specifically target Afrormosia, neither does it spare it.

“I make charcoal because there are no job alternatives,” explains a young man tending two parallel 60-foot-long kilns in a recently cleared patch of forest. The wood smolders beneath piles of earth, sending out ribbons of smoke for up to three weeks as the high temperature and low oxygen combine to transform the wood into charcoal. The charcoal is then cooled, bagged, and dragged to the river’s edge. He earns $5 for each 100-pound sack and expects to haul 50 bags from this site alone.

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Some of the charcoal made in Yangambi is used locally for cooking, but most is shipped upriver to Kisangani where the market is larger and prices are higher, and where electricity is unreliable and gas is expensive.

Reliable figures are hard to come by, but according to the Yale Global Forest Atlas, 90 percent of the wood taken out of African forests is used as fuel, mainly for home cooking. Meanwhile, the monitoring group Global Forest Watch calculates that Congo has lost 6.7 percent of its tree cover this century alone. Afrormosia’s proximity to fast-growing urban centers such as Kisangani puts it at particular risk.

Controls on deforestation — whether for homes, farms, timber, or charcoal — are part of the solution, but so too is the science underway in Yangambi. The researchers there are discovering how to maintain both the ecosystem and the economy, how to continue the coexistence of trees and humans and, therefore, the biodiversity of the entire forest. By producing useful science, they can determine which trees, and how many, can be logged.

The Congo Basin forest — hard to reach, difficult to work in, and, like Yangambi itself, suffering decades of scientific neglect in the wake of the colonial experiment — is in some ways still something of a black box to decode. Scientists don’t yet know what they don’t know about trees like Afrormosia.

But what the Yangambi scientists understand, acutely, is that if the logging continues unabated, Afrormosia will not survive and its disappearance will suck the life from the forest, and the economy.

“If we do not control logging activities, we could lose the species completely,” says Kafuti, of the tree that he and his colleagues have spent years getting to know. Failure will doom Afrormosia to extinction, contributing to the vice-like narrowing of the Earth’s biodiversity, and will have ripple effects through the Congo Basin, and the whole world. Even the progress currently enjoyed at Yangambi remains tenuous: Congo has yet to break free from over a century of venal misrule, and conflict exerts an almost gravitational pull on parts of the country.

Yangambi has led the world before and — during its years of abandonment, collapse, and decay — has been proof of what politics can do to a place. That history makes its existence today as an improbable island of scientific research all the more remarkable.

Tristan McConnell is a writer and foreign correspondent living in Nairobi, Kenya. He can be found on Twitter at @t_mcconnell.

Sarah Waiswa is a Uganda-born, Kenya-based documentary and portrait photographer.

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