INERA pisciculture research station in Yaekama, DR Congo. Photo by Axel Fassio/CIFOR

Field data is essential to gain an understanding of the genesis, development, contemporary function, and extent of the central Congo peatlands, also known as the Cuvette Centrale. But recent research shows that the hard-to-reach nature of these peatlands, which makes them costly and time-consuming to access, is one of the biggest factors inhibiting the collection of such data. However, this isolation also contributes to the region’s relatively low level of degradation.

In Chapter 9 of the recent report on the state of Congo Basin forests produced by the Observatory for Central Africa Forests (OFAC), experts said that complementing satellite data with field data and observations is crucial for the calibration and validation of peatland maps to reduce uncertainties. It also helps to provide additional information regarding vegetation typologies, carbon stock stored in the peat soil, biodiversity, and local community presence in and use of these areas.

About the Cuvette Centrale

Estimated to cover 145,500 square kilometres, the central Congo peatlands straddle Congo and DR Congo, making the complex the world’s largest near-contiguous tropical peatland. The vast Cuvette Centrale, which has remained relatively intact to date, holds roughly 30 gigatonnes of carbon – the equivalent of 15 years of carbon emissions from the United States economy. Field measurements of peat depth, bulk density, and carbon concentration showed that the amount of carbon stored in the peat is much greater than that stored in the living vegetation overlying the peatland – a quantity equivalent to the above-ground carbon stocks of the entire Congo Basin’s tropical forests. “If all the carbon stored in the central Congo peatlands were released to the atmosphere, this amount of carbon would be equivalent to three years of the current annual global emissions of carbon from all fossil fuel use,” said Jean Jacques Bambuta, peatland management unit coordinator for DRC’s Ministry of Environment and Sustainable Development and one of the contributors to the report.

The region also has rich and unique biodiversity. The highest density of western lowland gorillas in the world are found in the central Congo peatlands, and the ecosystem also plays host to species such as chimpanzees, forest elephants, endemic bonobos, and Allen’s swamp monkeys, which are endemic to swamp and inundated forests. The peatlands also harbour more than 200 water species including crabs, freshwater molluscs, crocodiles, turtles, and a wide diversity of fish.

Map of the central Congo peatlands (areas in purple and red) spanning Congo and DRC. Source: OFAC, 2020; Dargie et al, 2017

Mapping challenges

To delineate permanently flooded areas like those in the Congo Basin, scientists have largely relied on the use of satellite Synthetic Aperture Radar (SAR) imagery. The process entails sending microwaves from SAR satellite sensors that penetrate through vegetation canopy to interact with tree stems and palm fronds, with the amount of radiation returning to the satellite depending strongly on how wet the ground is: wetter ground means more returns to the satellites. But the approach has been found to guarantee only the amount of wetland present, and not peatland-specific information. It is against this backdrop that the authors underscore the need for further field research to map peatland extent and depth; identify and characterise peatland forest types; and understand local community use and value of these areas, amongst other topics.

Threats and pressures

The researchers also identified several potential pressures which threaten to destabilise the highly sensitive ecosystem of the central Congo peatlands. Notable amongst them is climate change, which has the potential to destroy ecosystem functioning across the entire sub-region. Any change in the peatland’s hydrological balance which results in a drop in the water table can increase the decomposition of organic matter, especially for rain-fed peatlands – likely transforming these from carbon sink to carbon source.

Since 30 timber concessions in DRC and seven in Congo coincide with the Cuvette Centrale, there is the risk that logging, be it legal or illegal, would likely open access to the peatland area – potentially disrupting the natural water drainage network. The exploitation of oil and gas from hydrocarbon concessions that lie within the peatlands also has the potential of disrupting their hydrology, as well as of polluting the sensitive ecosystem, increasing greenhouse gas emissions, and leaving undesirable socio-economic impacts like the displacement of communities.

Another cause for concern is the rise of oil palm plantations and the expansion of agricultural activities – both subsistence and industrial – into peatland areas. Such activities go hand in hand with requisite infrastructure such as roads, and a work force, which often requires people to migrate.

While these threats are unlikely to unfold in an isolated context, the researchers said that the extent to which they can occur will depend on numerous political and socioeconomic factors, both at national and international levels. Synergies between these threats could exacerbate negative impacts on the peatlands.

According to Raoul Monsembula of the University of Kinshasa, another author of the report, peatland drainage alters vegetation cover, threatens wetland biodiversity, decreases water quality, causes land subsidence, increases fire frequency, and has other negative impacts on people, their livelihoods, and the environment. “After peatland damage has occurred, efforts to re-wet and restore peatlands can be very costly and may not succeed in restoring original levels of ecosystem services provisioning,” he said. “Therefore, prevention is essential –especially in the relatively intact Central Congo peatlands.”

Though agreements and conventions such as the Ramsar Convention, the United Nations Environmental Assembly Resolution (UNEP/EA.4/RES.16), and the Brazzaville Declaration on Peatlands do exist, it will be critical to apply and implement these effectively in the years to come, given the global ecological importance of this ecosystem.

This article is also available in [French]