Mist from trees transpiring, Congo Rainforest
Tropical rainforest in the Republic of the Congo. The mist is from the trees transpiring in the heat. © M Harvey / WWF

Congo Rainforest Could Vanish by 2100

The Congo Rainforest is located in the Congo River Basin in Central Africa, in a region known as west equatorial Africa. It is the second largest tropical rainforest in the world, after the Amazon Rainforest in South America. The Congo Rainforest contains 90 percent of all Africa’s rainforest, and about a quarter of all tropical rainforest outside the Amazon Basin.

The Congo river – Africa’s second longest river after the Nile – originates in the Albertine Rift Mountains, the western branch of the continental East African Rift. Including its upper tributaries – the Chambeshi, Uele and Ubangi Rivers – and its lower tributary – the Lualaba River – the Congo River system runs for 4,700 kilometers (2,920 mi), terminating in the Gulf of Guinea on the Atlantic coast.

As a whole, the Congo River Basin (or simply ‘the Congo’) occupies roughly 4 million square kilometers (1.5 million sq mi), or around 13 percent of the African continent.

How Big is the Congo Rainforest?

The Congo Rainforest covers an area of about 2 million square kilometers – 3 million sq kms if savanna forests are included. As well as swamps and wetlands, the Congo is home to some of the largest tracts of undisturbed tropical rainforest on the planet. These forests are a priceless asset in the fight against climate change and loss of biological diversity.

The Congo Rainforest extends across six countries. These include: Cameroon, Equatorial Guinea, Gabon, Republic of the Congo, Central African Republic (CAR), and the Democratic Republic of the Congo (DRC). 1 In the DRC alone, it covers an area equivalent to that of France, Spain, Britain and Ireland combined.

The Congo actually consists of five different areas of humid forest, and three areas of savanna mosaic at the northern and southern edges of the basin. The only other areas in Africa that contain significant amounts of humid forest are the Guinean lowlands in West Africa, which extend from Sierra Leone to Cameroon; the coastal forests of East Africa, from Kenya to Mozambique; and the island of Madagascar.

The Congo rainforests provide food and shelter to more than 75 million people. In addition, they regulate the flow of water and the climate, protect the soil, control disease and safeguard water quality. They have been inhabited by humans for more than 50,000 years and currently support almost 150 separate ethnic groups, including the Ba’Aka, Bambenga, Bambuti and Batwa people, many of whom still practice a traditional hunter-gatherer lifestyle. 2

The climate of the Congo is equatorial tropical, characterized by two rainy seasons with very high rainfalls, and high temperatures all year round. The Congo is home to the critically endangered western lowland gorilla, as well as other endangered species like chimpanzees, and forest elephants.

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Map of Africa's primary tree cover
Map showing Africa’s primary rainforests and tree cover. Photo: Mongabay 3

The Congo Rainforest Biome

In the interior of the Congo River basin, the lowland forests descend from about 1,000 meters on the eastern rim of the Albertine Rift Mountains, into the lower basin towards the west.

The single most extensive ecoregion of the Congo Basin is the northeastern lowland forest, which is situated in the eastern part of Democratic Republic of the Congo and extends into southern Central African Republic. This region includes the Ituri forest as well as a number of protected areas.

Downriver to the west are the central lowland forests, a similar habitat of intact, dense forest. Also, on both sides of the Congo River are the swamp forests. The Congo River is an impenetrable barrier for numerous types of animal, and several species of primates are confined to one or other side of the river.

Continuing downstream we find the northwestern Congolian lowland forest and the Equatorial coastal forests, which extend into the Republic of the Congo, Cameroon and Gabon. Located in this region are forests of Gilbertiodendron dewevrei trees (Fabaceae).

Near the Atlantic coast, rainfall is heavier and the forests are slightly wetter than in the interior. Here we find the richest biodiversity of wildlife (animals and plants) in the entire Congo basin.

In the north and south, the Congo rainforest switches to a drier ecosystem of forest savanna. Here, most of the forest is semi-deciduous, with deciduous trees forming the upper canopy layer of the forest, mixed with evergreen species, while understory trees and shrubs tend to remain evergreen.

These savanna woodlands are usually found on plateaus approximately 600 meters in elevation. Common species of tree found here, include: Afzelia africana, Aningeria altissima, Chrysophyllum perpulchrum, Cola gigantea, Khaya grandifoliola, and Morus mesozygia.

Moving further into the grassland miombo biome to the north and south, tree species include Burkea africana, Combretum collinum, Hymenocardia acida, Isoberlinia, Pariniari curatelifolia, Stereospernum kunthianum, Strychnos and Vitex spp.

Woodland savannas, being more accessible by road, have undergone greater land use change to agricultural grazing and farmland.

Rainfall in most of Congo’s humid forest averages around 1,500-2,000 mm per year. Forest savanna biomes are drier, averaging 1,200-1,600 mm of rain, with clearly defined wet and dry seasons. Wetter coastal forests in Gabon typically experience up to 3,000 mm annually.

From the Atlantic coast, rainfall normally decreases as the air stream moves inland from west to east. In the process, the lowland Congolian forests gradually give way to the higher Albertine Rift montane forests, which blanket the mountains lining the Albertine Rift, a section of the East African Rift complex.

The Congo’s interior forests have relatively continuous rainfall throughout the year, whereas western regions experience a dry season from January through March. Interior areas of forest stand on highly weathered oxisol soil, noted for its bright red color, but drier areas to the south as well as the volcanic lands of the Albertine typically contain more nutrient-rich soils.

Map showing the Congo River watershed
Map showing the Congo River watershed in West-Central Africa along with surrounding states and borders. © Hel-hama / geologypage.com

Wildlife

Overall, the diversity of plants in the Congo basin is high, with roughly 10,000 tropical plant species, of which 30 percent are endemic to the region, although it is not as diverse as that of the Amazon Rainforest in Brazil. Tree species are also many and varied, except there are fewer understory shrubs, mosses and ferns. This is due to the slightly drier climate. The most biologically diverse regions of the Congo are the Atlantic equatorial forests of Cameroon and Gabon, along with the foothills of the Albertine Mountains along the border with Rwanda, Burundi and Uganda.

African woodland savannah habitats are home to large mammals including elephant, rhino, hippos, forest buffalo, lion, okapi, leopards, and bongo antelopes.

Species of mammals which occur nowhere else include: the common chimpanzee (Pan troglodytes), the bonobo (Pan paniscus), okapi (okapia johnstoni), numerous species of monkey like the sun-tailed guenon (Cercopithecus solatus), Dollman’s tree mouse (Prionomys batesi), Remy’s shrew (Suncus remyi), and the Sylvisorex konganensis shrew.

Endangered species of wildlife include: chimpanzees, forest elephants and bonobos, as well as the critically endangered mountain gorillas. The Congo region is also home to 400 other mammal species, more than 1,000 species of birds and 700 species of fish.

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Ituri rainforest in northeastern Congo
Part of the Ituri rainforest in northeastern DRC (Democratic Republic of the Congo, formerly known as Zaire.) The forest is named after the Ituri River which flows through the rainforest, connecting to the Aruwimi River and then to the Congo River. Photo: © MONUSCO / Abel Kavanagh (CC BY-SA-2.0)

Deforestation in the Congo

Up until 2000, the rate of deforestation in Central Africa was extremely low, in fact it was the lowest of any major forest region in the world. Since then, however, the rate has risen due to political violence and instability throughout the region. During the 15-year period 2000-2014, it averaged about 11,000 square kilometers per year, or a third of one percent of its total.

Since then, the rate has risen even higher. In the past 5 years (2014-2018), for instance, deforestation in the Democratic Republic of the Congo has doubled. 4

For example, in 2018, primary forest loss in the Democratic Republic of the Congo was 38 percent higher than it was from 2011-2017. Small-scale forest clearance for agriculture and wood supplies accounted for about three-quarters of this loss. 5

The latest assessment is contained in a five-year report released in 2020 by the United Nations Food and Agriculture Organization (FAO). The report states that Africa had the largest annual rate of net forest loss in 2010–2020, estimated at 40,000 square kilometers per year, followed by South America, at 26,000 square kilometers per year. 6

Deforestation for the remainder of the century is likely to be shaped by demographic changes combined with a growth in new commercial opportunities in mining, timber and plantation crops. Recently, for instance, loss of rainforest in Ghana and Côte d’Ivoire has accelerated by 60 percent and 26 percent respectively, due to illegal mining and the expansion of cocoa farming. 7

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What are the Biggest Threats to the Congo Rainforest?

As of 2020, there are two main threats to the rainforests of the Congo River Basin: clearance by subsistence farmers, and logging (both legal and illegal).

Clearance by Subsistence Farmers

Right now, the biggest threat is deforestation by poor farmers. And the threat is likely to grow significantly, as the United Nations is forecasting a fivefold increase in the size of the human population in the Congo Basin by 2100.

This warning comes from a recent study of the Congo by researchers from the University of Maryland, which finds, for example, that all primary growth forest in the region will disappear by the end of the century. 8

The study shows that the Congo Basin lost around 165,000 sq kms (64,000 sq mi) of forest during the 15-year period 2000-2014. That’s about 5.5 percent of its total. The main reason for the loss – accounting for 84-90 percent of it – is small-scale deforestation by subsistence farmers armed with simple axes.

Unfortunately, 60 percent of the deforestation during the period occurred in primary forests, and mature secondary forests. These are the most carbon-rich areas: the ones likely to release most carbon dioxide into the atmosphere.

The main driver of forest clearance in the Congo, is poverty, caused by ongoing political instability in the region. The instability is forcing people into the forest for safety. Left with few options to make a living, most survive by carving small plots of land out of the forest. These plots are farmed until the soil becomes depleted of nutrients, whereupon a new area is cleared and planted.

Poverty also breeds sickness and disease. For example, many inhabitants of the Congo Rainforest do not have money to buy more efficient fossil fuels such as LPG. As a result, they have to rely on burning wood and charcoal on open indoor fires for cooking and heating. Unfortunately, burning this type of solid fuel releases large amounts of inhalable particulate matter, which is a major cause of indoor air pollution that kills 3.8 million people annually, mostly in Africa and Asia.

The Democratic Republic of the Congo (DRC), which owns about 60 percent of the rainforest ranks extremely low on the Human Development Index (HDI), which is used by the United Nations Development Programme to assess human quality of life. Indeed, its per capita education, lifespan and GDP are among the lowest in the world.

Roads enable wood logging in Africa
Built initially to enable the extraction and transportation of wood, logging roads in the Congo Rainforest pose several threats to wildlife, conservation, and local resources. Photo credit/InfoCongo

Logging in the Congo Rainforest

As of 2020, the only country in the Congo Basin where deforestation by individual farmers isn’t the main problem, is Gabon. Here industrial logging is the biggest cause of forest loss. But this may change in view of the inexhaustible demand for timber from around the globe. China, in particular, is importing huge quantities of wood products from the forests of Gabon and Cameroon, where commercial logging attracts less media attention than in the Amazon. Expect a new wave of logging to break out across the Congo Basin, especially in areas where corruption and an absence of environmental law enforcement remains the norm.

Logging roads have already opened up vast areas of the Congo’s interior to other commercial activities, including commercial deforestation as well as hunting, which has led to a poaching epidemic in some areas, resulting in a 60 percent drop in the region’s elephant population in less than a decade.

All this is confirmed in a new study published recently in Nature Sustainability. The study, using satellite imagery, shows that logging roads are expanding dramatically in the Congo Basin. Since 2003, the length of roadway has increased from 144,000 to 231,000 kilometres. This has resulted in a catastrophic fall in animal populations.

At the same time, the rate of forest destruction caused by new roads in the Congo Basin has quadrupled since 2000. 9

Worse still, the new roads have triggered an avalanche of ecologically damaging activities, including illegal deforestation, mining, and land speculation.

Professor Bill Laurance of James Cook University, one of the co-authors of the study, says: “Industrial logging is a key economic driver for much of the road building. Some logging roads are abandoned, but many are used by slash-and-burn farmers and poachers to penetrate deep into surviving rainforests… Elephants, gorillas and chimps hardly have anywhere to hide from poachers now.”

Land use map of the Congo River Basin
Land use map of the Congo River Basin, showing the 6 principal land use categories. Image: © C.A.Mushi, et al 2019. 10

Why is the Congo Rainforest So Important?

There are at least six reasons why the tropical rainforest of the Congo should be preserved and safeguarded.

1. It Reduces Global Warming

The Congo rainforest plays an important role in climate change mitigation by absorbing carbon dioxide from the atmosphere during photosynthesis. By locking up CO2 in its trees, the forest prevents it from adding to global warming and damaging the planet.

Scientists have also discovered vast peatlands in the Cuvette Centrale depression of the central Congo Basin. The peatlands cover only 4 percent of the basin, but contain the same amount of carbon as that stored above ground in the trees covering the other 96 percent. 11 In total, The Congo holds around 8 percent of the world’s forest-based carbon in its trees and soil.

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2. It Plays a Vital Role in the Water Cycle

Another adverse effect of deforestation in the Congo is the damage it causes to water supplies. In the tropics, trees play a vital role in the local and regional water cycle, due to a combination of heat absorption and transpiration, which recycles the water drawn up by the trees from the soil, providing extra moisture for the forest as a whole. The process conserves rainfall in times of shortage and prevents surface run-off during heavy downpours. It also boosts cloud formation and thus reflects heat from the sun, further reducing the impact of climate change.

But when trees are cut down, less moisture is absorbed by plant roots, so less water vapor is transpired into the atmosphere, causing fewer rain clouds and thus less rainfall. Within a few years the area can become dried out as strong tropical sunlight bakes the forest-savanna.

3. It Prevents Soil Erosion

Forest trees hold onto the soil preventing erosion. When they are cut down, the soil is more easily eroded by wind and rain. And if the soil disappears so do the plants and any crops. (See: Why is Soil So Important to the Planet?)

The speed of soil erosion following an episode of deforestation can be surprisingly quick. A study conducted in Côte d’Ivoire, for instance, compared the soil stability of forested slopes with that of cultivated slopes. It revealed that forested slopes lost a mere 0.03 tons of soil per year per hectare (2.5 acres), compared to 90 tons per hectare lost by cultivated slopes, while bare slopes lost a total of 138 tons of soil per hectare.

4. It Maintains Water Quality

When more soil is eroded and washed into rivers, more silt is deposited on the river bed. This reduces river flow and decreases local water quality. The impact of such silt deposits is felt all the way to the sea, resulting in greater flooding along with a decline in the health of tropical coral reefs, as well as blue carbon ecosystems such as coastal mangrove forests, and other wetlands.

5. It Sustains Biological Diversity

Roughly 80 percent of the world’s land-based biodiversity is found in forests – from the evergreen forests of the northern taiga to the rainforests of the tropics. One of the most harmful effects of deforestation is the loss of biodiversity caused by the degradation of animal habitats. Some scientists think that tropical rainforest deforestation is contributing to the ongoing sixth mass extinction, citing it as another reason to rename our present era the ‘Anthropocene epoch’, in order to fully reflect our dominance as the new super predator. According to a recent report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2019), roughly 1 million animal and plant species are now threatened with extinction, many within decades. 12

6. It Provides Important Ingredients for Medicines

A report by the Royal Botanic Gardens Kew, entitled “The State of the World’s Plants”, says that one in five of all 31,000 plant species are threatened with extinction due to deforestation, and this is placing future supplies of new drugs in jeopardy, since 57 percent are used in the manufacture of drugs. 13

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References

  1. Global Forest Atlas. “The Congo Basin Forest.” []
  2. “Congo Basin.” WWF. []
  3. “Mongabay” []
  4. NYDF 2019 Progress Report: Protecting and Restoring Forests. []
  5. “The World Lost a Belgium-sized Area of Primary Rainforests Last Year.” World Resources Institute. []
  6. “Global Forest Resources Assessment report.” (FRA 2020) FAO. []
  7. Global Forest Watch. April 2020 []
  8. “Congo Basin forest loss dominated by increasing smallholder clearing.” Tyukavina, A., et al. (2018) Science Advances 4 (11). []
  9. “Road expansion and persistence in forests of the Congo Basin.” Nature Sustainability (2019). []
  10. “Assessment of basin-scale soil erosion within the Congo River Basin: A review.” C.A.Mushi et al. Catena. Volume 178, July 2019, Pages 64-76. []
  11. “Age, extent and carbon storage of the central Congo Basin peatland complex.” Dargie, G., Lewis, S., Lawson, I. et al. Nature 542, 86–90 (2017). []
  12. “UN Report: Nature’s Dangerous Decline Unprecedented; Species Extinction Rates Accelerating. Sustainable Development Goals. UN.org []
  13. “One in five of world’s plant species at risk of extinction.” Damian Carrington. The Guardian. 10 May 2016 []
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