Guest article: A plan to solve the mysteries of Congo’s vast peat bogs

extraction of a sample from the peat bog of the congo basin
Extraction of a sample from the peat bog of the Congo Basin. Credit: Greenpeace

Simon Lewis is Professor of Global Change Science at the University of Leeds and University College London , as well as contributing to the writing of Carbon Brief 

— In 2017, I led a team of scientists to the publication of the very first map that highlighted the existence in the Central basin of the Congo Basin of the largest peatland complex in the tropics in the world, with an area of 145,500 square kilometers, which is larger than the area of ​​England.

Peat is a type of wetland soil made from partially decomposed plant material and is rich in carbon. We estimate that a reserve of about 30 billion tonnes of carbon is contained in the peatlands that we have discovered, the equivalent of three years of global emissions related to fossil fuels.

Given the carbon stored in peatlands, protecting them has become a global priority. Following our discovery, the Republic of Congo and the Democratic Republic of Congo (DRC) both signed the Brazzaville Declaration, an agreement that aims to protect and preserve this valuable ecosystem.

distribution of wetlands in the central cuvette in africa
Distribution of wetlands in the Central Cuvette in Africa


Although most of them are intact and more and more protected in writing, in reality peatlands are threatened by the extension of the road network, logging and oil extraction, and the drainage of water in order to develop industrial plantations. of oil palm. In addition, rising temperatures could reverse the balance of peatlands, to the point where they will release carbon into the atmosphere instead of containing it.

The good news is that this month we have started the second phase of the CongoPeat project, a major five-year scientific program that has received £ 3.7 million in funding from the Research Council of Europe. Natural Environment ( NERC ) of the UK Government.

The program aims to gain a global understanding of this carbon-rich ecosystem by answering key questions about its past, present and future.

The past: why did peatlands form?

Radiocarbon dating of peat – up to five meters below surface – has revealed that peatlands began to form nearly 10,000 years ago, after the retreat of the last glaciation, when Central Africa became warmer and wetter.

Based on this initial discovery, we will painstakingly reconstruct the past vegetation of the area by taking peat carrots and using the old pollen grains trapped therein.

Under the direction of Dr. Ian Lawson of the University of St Andrews , pollen analysis will help us understand the initial formation of peatlands and the changes they have undergone.

Prof. Susan Page and Dr. Arnoud Boom from the University of Leicester will pursue further analyzes of “indicators”, such as the chemical composition of wax on the surface of partially decomposed leaves preserved in peat. These indicators provide a record of changes in temperature and precipitation rates over time, which will allow us to reconstruct the past climate of the region.

This research will allow us to discover how changes in temperature and precipitation rates in the past have affected the accumulation or emission of carbon in peatlands. We will also be able to understand the extent to which peatlands will remain stable under current and future climate conditions.

The present: how do peatlands work today?

To better protect and manage peatlands, we need to know the precise location of peat, the amount of carbon stored by peatlands and the role they play in the tropical forest ecosystem.

We will be able to map the distribution of different vegetation types using satellites, but since this method will not detect peat directly, field data will be essential.

With our partners from both Congo, Dr. Suspense Aware Ifo from Marien N’gouabi University, Republic of Congo, Dr. Corneille Ewango from Kisangani University, Democratic Republic of Congo, and Dr. Mark Gately from WCS Congo, we will undertake a series of expeditions across the entire region to collect peat samples and estimate its thickness and carbon content.

Under the direction of Dr. Greta Dargie from the University of Leeds , the team will spend weeks traveling by boat and on foot, venturing into the heart of the peat bogs, while avoiding the endemic dwarf crocodiles, to map the marsh vegetation of peat, measure the thickness of peat and return peat samples to UK laboratories.

plan of the three main expeditions that the researchers will undertake
Plan of the three main expeditions that the researchers will undertake, labeled 1 to 3. On the map, the peat bogs are indicated in green, the yellow and the blue show the sites where new samples will be taken and the orange shows the sites where has already taken samples in the Republic of Congo. Credit: Greta Dargie


By putting this information together with the satellite data, we can then produce new accurate peatland maps.

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Data from the DRC was not included in the original peatland discovery, which is of paramount importance because we estimate that it is home to two-thirds of the peat and carbon zoned. The new phase of the project, with the data that will be collected in the DRC, will enable us to verify this hypothesis and to make available the first maps drawn from data of peat bogs in the DRC.

Peatlands play an important role not only in capturing carbon from the atmosphere: these wetlands release large amounts of the greenhouse gas, methane , because they are saturated with water.

Under the direction of Dr. Sofie Sjögersten of the University of Nottingham, data will be collected and analyzes made to assess for the first time the extent of field emissions.

These measures will be supplemented by intensive sampling of a well-studied site. PhD students at Marien N’gouabi University will monitor carbon exchanges between the atmosphere, vegetation and peat in two years. Researchers will measure each month several parameters that characterize the functioning of this ecosystem, including thin litterfall (leaves, twigs, bark) and dead wood to peat, and their decomposition rates.

Finally, in order to obtain estimates of carbon stocks and greenhouse gas emissions across the region, all of our field measurements will be scaled up using satellites. To facilitate this, we will get a detailed picture of the topography – the physical aspect of the area – by deploying a drone.

Under the direction of Dr. Ed Mitchard of the University of Edinburgh , this aspect of the project will establish the importance and role of peatlands in the global carbon cycle.

The future: are peat bogs stable?

In order to make projections for the future of peatlands, we will have to use models. We will use the measurements made by the research team to develop a Congolese version of DigiBog , a model that simulates the development of peatland ecosystems.

Under the direction of Prof. Dr. Andy Baird of the University of Leeds , DigiBog will show the “growth” or “destruction” of peatlands according to the input of data, such as the amount of carbon added to the soil from plant material and the rate of decomposition of these.

We will be able to use the model to simulate deforestation, which will allow us to evaluate the effect of logging on the carbon stock in peat. Virtual drainage can also be dug to estimate the amount of carbon that will be released to the atmosphere if the peat is drained for palm oil planting, for example.

However DigiBog is not suitable for use in global climate models . To achieve them, we will need to join the global modeling efforts that are underway. We will improve the UK’s global land surface model called JULES (Joint UK Land Environment Simulator) to include tropical peatlands. This work will be conducted under the direction of Prof. Richard Betts of the University of Exeter and the Hadley Center of the Met Office (the official department of meteorology in the UK).

This will allow us to examine how Congolese peatlands will respond to possible future climate scenarios. So we can answer the fundamental question: are these peatlands a new point of imbalance within the Earth system?

Links to the policy

The ambition of our project, CongoPeat, is to provide policymakers and civil society with timely information in a format that is useful to them. Dr. Lera Miles , of the World Conservation Monitoring Center (UNEP World Conservation Monitoring Center), will lead a project that aims to present our scientific results in language that is accessible to those involved in the protection and protection of nature. peatland management.

This very important stage of our project will be carried out with the continued support of international organizations such as the Global Peatland Initiative , the governments of the two countries, the Republic of Congo and the DRC, WCS Congo and the communities living in the vicinity peatlands, which should ensure that our work leaves a positive and lasting legacy.

by Simon Lewis | Carbon Brief



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