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Story Publication logo December 13, 2019

Supertrees: Meet Congo’s Caretaker of the Forest


Amazon rainforest as seen from above. Image by Vox. Brazil, 2019. 

Tropical forests in Indonesia, Brazil, and Democratic Republic of Congo are under-appreciated...

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Jean-Pierre Muzinga, a forest technician, measures the trunk of an Afrormosia in the Yangambi Biosphere Reserve. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
Jean-Pierre Muzinga, a forest technician, measures the trunk of an Afrormosia in the Yangambi Biosphere Reserve. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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.

Dieumerci Kibinda, a Congolese botanist, calls Afrormosia “the most beautiful tree.” Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
Dieumerci Kibinda, a Congolese botanist, calls Afrormosia “the most beautiful tree.” Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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 Djofack, 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.

Muzinga stands in front of a sun-kissed Afrormosia tree. He and others who work at the Yangambi Research Station form special bonds with the trees. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
Muzinga stands in front of a sun-kissed Afrormosia tree. He and others who work at the Yangambi Research Station form special bonds with the trees. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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.

A sanded section of an Afrormosia trunk. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
A sanded section of an Afrormosia trunk. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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.

The dark green area is where the only major population of Afrormosia remains. The shaded area is where it was found as of 1950. (The black dot is the Yangambi Biosphere Reserve in Congo, where we visited Afrormosia.) Image by Amanda Northrop / Vox.
The dark green area is where the only major population of Afrormosia remains. The shaded area is where it was found as of 1950. (The black dot is the Yangambi Biosphere Reserve in Congo, where we visited Afrormosia.) Image by Amanda Northrop / Vox.

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.

The researchers at Yangambi found this fallen Afrormosia tree and planned to use it in their studies. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
The researchers at Yangambi found this fallen Afrormosia tree and planned to use it in their studies. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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 labour 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 Belgium, Djofack, 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?”

The scientists at Yangambi are using this crumbling colonial map to understand how Afrormosia grows. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
The scientists at Yangambi are using this crumbling colonial map to understand how Afrormosia grows. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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 Djofack’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, Djofack 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 Djofack, 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.

Hulda Hatakiwe, a forestry engineer who manages the Afrormosia nursery in Kisingani, checks on the health of the leaves. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.
Hulda Hatakiwe, a forestry engineer who manages the Afrormosia nursery in Kisingani, checks on the health of the leaves. Image by Sarah Waiswa. Democratic Republic of Congo, 2019.

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.

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.