Congolian lowland forests
The Congolian lowland forests are a significant tropical rainforest biome located in Central Africa, primarily spanning countries such as Cameroon, Gabon, Republic of Congo, northeastern Democratic Republic of Congo, and southern Central African Republic. This unique ecosystem is characterized by its rich biodiversity, hosting approximately 10,000 plant species, with around 30% of these being endemic. Notable tree species include the limbali, a vital component of the forest, along with various hardwoods and palms that provide essential resources for local wildlife and human inhabitants.
The forests are home to iconic species such as the western lowland gorilla and the forest elephant, both of which play crucial roles in the ecological balance of the area. Despite relatively low human population density, the region faces significant threats from logging and poaching, exacerbated by the economic pressures from armed conflicts. Conservation efforts are underway, with several national parks designated as protected areas, including UNESCO World Heritage Sites.
These lowland forests are also recognized for their critical role as carbon sinks, helping to mitigate climate change by absorbing carbon dioxide. The preservation of this biome is essential not only for the local ecosystem but also for global environmental health.
Congolian lowland forests
- Category: Forest Biomes.
- Geographic Location: Central Africa.
- Summary: About one-third of this vast forest is classified as remote or frontier; it is a stronghold of the western lowland gorilla.
The Congolian lowland forests of central Africa stretch across Cameroon, Gabon, Republic of Congo, northeastern Democratic Republic of Congo, and southern Central African Republic. Forest savanna lies to its north and south, the Atlantic Equatorial Coastal Forest biome lies to its west, and montane forest to its east. In general, elevations are higher than those of the other large global block of tropical forest (in the Amazon), here reaching 980 to 3,280 feet (300 to 1,000 meters).
Rainfall averages 63 to 78 inches (160 to 200 centimeters) annually across the Congolian lowlands. Much of the greater regional precipitation is generated by evaporation from these central rainforests. Geologic elements include the alluvial-derived soils of the Cuvette Centrale basin, within the arc of the Congo River, but also ancient pre-Cambrian bedrock in the northern sections of the biome. Oxisols, a fairly fertile soil type, also exist and are typical of highly leached tropical rainforest.
Plant Types
Of the roughly 10,000 higher plant species found here, researchers estimate that 30 percent are endemic, or evolved for this biome and found nowhere else on Earth. The limbali (Gilbertiodendron dewevrei) is a characteristic evergreen tree species here. Much like some of the other flowering hardwoods found in the Congolian lowland forests—such as muhimbi (Cynometra alexandri) and mnondo (Julbernardia serettii)—the limbali is considered a gregarious grower, often found in dense stands that permit almost no other tree species. These trees, all members of the Leguminosae (also called Fabaceae) family, are vital to the animals, insects, and humans here for various reasons, not least being their ample production of nutritious pods, seeds, and essential oils.
Raffia palms, which are most commonly found along rivers, can be found here. Drypetes shrubs, Lianas, rattans, raffia, sisal all are part of the biome. Some plants, like cinchona and rauwolfia, are used by inhabitants of the area for traditional medicine.
Characteristic Fauna
The vast expanse of remote forest harbors large mammals that include the iconic western lowland gorilla (Gorilla gorilla gorilla) and forest elephant (Loxodonta africana cyclotis). The western lowland gorilla is by far the most common gorilla species here, numbering up to 200,000. This primate feeds on as many as 100 different fruit species, and its preferred habitat ranges from sea level to 5,250 feet (1,600 meters) in elevation. Some of this gorilla's forest habitat is so remote that, in 2007, the Wildlife Conservation Society discovered 125,000 lowland gorillas, previously unrecorded, living in a remote northern region of the Republic of Congo.
Some savanna wildlife types have evolved forest species or subspecies in this ecosystem; among them are the forest elephant and Okapi giraffe. The northwestern reaches of the Congolian Lowland Forest biome have the highest richness of mammal species, and among the highest rates of endemism, of any forest in Africa, including for primates. The countries of Gabon and Congo have 190 and 198 endemic mammal species, respectively. Bird, reptilian, and amphibian species endemism is also high.
Threats and Conservation
Human populations are relatively low in density here. They include long-standing pygmy tribes such as the Baka, along with Bantu farmers. More than 60 million people live in the wider Congo River basin, however, and their presence is felt. Critical threats to wildlife species such as elephants and bonobos include logging and poaching. The effect of decades of armed conflict in the eastern Congo has stressed the region's cash-based and subsistence economy, and has made local populations even more immediately dependent on natural resources. Enforcement of poaching laws has proven cumbersome in the large reserves; results tend to be frustratingly uneven.
Major reserves that include Congolian lowland forest in part or whole are Kahuzi-Biega, Okapi, and Salonga National Parks. The latter is also a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site, as are the Lope-Okanda Ecosystem and Relict Cultural Landscape in Gabon, as well as the relatively new, 9,650-square-mile (25,000-square-kilometer) Sangha Tri-National Protected Area a vast reserve located within Cameroon, Central African Republic, and the Republic of Congo.
Since Wildlife Conservation Society biologist Michael Fay's highly publicized Megatransect project documented vast expanses of relatively pristine forest in the region in 1999, the government of Gabon has been especially supportive of new protected areas. By 2005, Gabon set aside approximately 10 percent of its land area as nature reserves, including Minkebe Forest in the northeast, rivaling as a conservation leader such renowned green nations as Costa Rica.
As a valuable and powerful carbon sink, the lowlands forests of central Africa deserve protection as a hedge against the runaway greenhouse effect that drives global warming. Deforestation here, by releasing stored carbon-rich gases in the leaves, wood, and soils—and by undercutting these forests' ability to absorb carbon dioxide already in our atmosphere—can literally affect local and regional environments around the world.
Bibliography
Auzel, P. and D. Wilkie. “Wildlife Use in Northern Congo: Hunting in a Commercial Logging Concession.” In J. Robinson and E. Bennett, eds. Hunting for Sustainability in Tropical Forests. New York: Columbia University Press, 2000.
Bryant, D., D. Nielsen, and L. Tangley. The Last Frontier Forests: Ecosystems and Economies on the Edge. Washington, DC: World Resources Institute, 1997.
Martin, Emma, and Neil Burgess. "Central Congolian Lowland Forests."One Earth, 2022, www.oneearth.org/ecoregions/central-congolian-lowland-forests/. Accessed 13 Nov. 2024.
Minnemeyer, S. An Analysis of Access into Central Africa's Rainforests. Washington, DC: World Resources Institute, 2002.
Weber, W., L. J. T. White, A. Vedder, and L. Naughton, eds. African Rainforest Ecology and Conservation. New Haven, CT: Yale University Press, 2001.