African tropical peatlands: their value and vulnerability

Africa is home to the planet’s most extensive tropical peatland complex, the Cuvette Centrale, Congo Basin, but knowledge of peatland ecosystems across the continent is poor. For many regions of Africa there is no quantitative data from peatlands and much of the information comes from decades-old grey literature reports, which often omit vital information such as the geolocation of the peatlands. Here we review available information on African peatlands in order to construct a clearer picture of the distribution, characteristics and formation of these ecosystems. Whilst much of the literature is ambiguous, vague and in need of verification, we find that the majority of African countries are cited as harbouring peatlands, signifying that peatlands are widespread across the continent. Furthermore, they appear to form under a wide range of environmental conditions suggesting a high diversity among the African peatland ecosystems. Peatland ecosystems play an important role in the global carbon cycle. It is now crucial that quantitative data from peatlands across the continent is collected in order to permit more reliable and recent C stock estimates for these ecosystems.

Dr Greta C Dargie

University of Leeds, UK

Dr Greta C Dargie

University of Leeds, UK

Dr Greta Dargie’s research has focused on the peatlands of the central Congo Basin since her PhD, where she produced the first map and carbon stock estimation for these peatlands. She is now a research fellow at the University of Leeds, where she works on the CongoPeat project, which aims to understand how the central Congo Basin peatlands developed, how they function present day and how they will respond under different land use and climate change scenarios. At the Royal Society meeting she will be looking at where else across the continent of Africa can peatlands be found.

The development of tropical peatlands is closely linked to local hydroclimatic conditions, as waterlogging is the primary mechanism enabling the accumulation of organic matter in tropical regions. Measuring the hydrogen isotope composition of plant waxes extracted from peat cores allows the reconstruction of past hydroclimatic conditions, offering insights into the formation and evolution processes of tropical peatlands. Here, we present a new plant wax hydrogen isotope (δDn-C29) record alongside a published record from peat cores in the Cuvette Centrale, Congo Basin — the world's largest tropical peatland complex, storing approximately 30 billion tons of carbon. The two records were obtained from contrasting settings: one from a river-proximal peatland and the other from a large interfluvial peat dome, representing different peat-forming regions of the Cuvette Centrale. Despite these differences, both δDn-C29 records show strong covariation, indicating that peatlands across the region developed under broadly similar hydroclimatic conditions. An increase in precipitation at the end of the last Ice Age initiated peat formation and drove intensification of peat accumulation across the Cuvette Centrale. Similarly, a drying trend around 5 ka impacted peat development at both sites, underscoring the close linkage between precipitation regimes and peatland development across different regions. The strong agreement between these two peatland records and a δDn-C29 record from the offshore Congo Fan further highlights the regional coherence of hydroclimatic evolution.

Dr Johanna Menges

University of Bremen, Germany

Dr Johanna Menges

University of Bremen, Germany

Johanna Menges is a postdoctoral researcher at the Geoscience Department of the University of Bremen, Germany. Her current work focuses on organic carbon storage and export along the Congo River employing a range of geochemical methods. Before that Johanna worked the MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany, in the French-German project ORACLE lead by Enno Schefuß and Yannick Garcin aiming at reconstructing Holocene hydroclimate and carbon cycle dynamics in the Central Congo Basin. She completed her Ph.D. in Biogeochemistry in 2020 at the German Research Center for Geoscience (GFZ) and University of Potsdam, Germany, where she investigated organic carbon dynamics in high mountain areas.

The central Congo Basin (CCB) contains one of the world’s most extensive regions of tropical peat swamp forest, occupying interfluves and floodplains surrounding the Congo River and its tributaries. The region is dominated by hardwood and Raphia-palm forests; however, little is known about how and when these forests developed. Here we present evidence for forest development via pollen analysis on peat cores from four study sites, two on floodplains to the East of the Congo River, and two on interfluves to the West of the Congo River. By comparing pollen records of vegetation succession from these four sites, we established two contrasting patterns of forest development; one pattern evolved from an open herbaceous wetland and the other from a hardwood swamp forest, both driven by autogenic and allogenic processes. When comparing the vegetation succession to records of past precipitation reconstructed from plant wax hydrogen isotopes (δDn-C29), we observed that a drying trend in the Late Holocene affected forest composition at all sites, with some sites being more sensitive to precipitation change than others. Our findings highlight the biological diversity and complexity of the CCB peatlands, but also their sensitivity to climatic change, providing important context for efforts to protect and conserve the CCB peat swamp forests.

Dr Donna Hawthorne

Queen's University Belfast, UK

Dr Donna Hawthorne

Queen's University Belfast, UK

Donna Hawthorne is a researcher and educator in physical geography and biogeography. Her work utilises palaeoecological methods, including the analysis of pollen and charcoal, to reconstruct past ecosystems and understand their responses to climate and human activities. During her doctoral studies at Trinity College Dublin, Donna conducted research on Ireland’s wildfire history, providing a baseline record of fire over the past 12,000 years, informing conservation and landscape management. Her postdoctoral research at the University of St Andrews focused on the Congo Basin's peatlands, a vital carbon store. She used proxies preserved in peat cores to reconstruct how the peatlands and forests developed and changed over the past 20,000 years and how they were influenced by climate change and human activity. Donna wishes to continue her research to advance our understanding of tropical peatlands through interdisciplinary approaches, aiming to safeguard these ecosystems for the future.

Palaeobotanical and geochemical analysis of sedimentary records across the Congo Basin have demonstrated how interactions between vegetation, hydrology, and geomorphology influence the trajectory of peatland development. Human impacts on this region unfold across scales from the global impacts of anthropogenic climate change to the local impacts of swidden agriculture and charcoal production. Conservation policies and restoration targets directly impact the livelihoods of millions of people who occupy fishing camps, villages, and permanent cities located in close proximity to the complex hydrogeological environments of the Congo River and its wetlands. Assessing the sensitivity and/or resilience of peatland environments to these local pressures requires looking at long-term changes in human population density and land use in this region. Major demographic and technological changes took place in Central Africa over the course of the Late Holocene (ca. 4 ka - present) and provide a model for estimating the risks posed by different human land use patterns. Here, we report results of paleoecological and geochemical analysis of sedimentary records from a range of geomorphic settings in the Congo Basin associated with different modes of human land use. Because detecting human impacts in palaeoenvironmental records is prone to problems of equifinality, we focus on establishing an empirical baseline for human-modified vegetation patterns in these contexts. We conclude by considering how the trajectory of Congo Basin peatland development contextualizes archaeological and historical models of forest settlement by Pleistocene hunter-gatherers, Holocene farmers, and historic populations alike.

Dr Christopher Kiahtipes

University of South Florida, US

Dr Christopher Kiahtipes

University of South Florida, US

Coming from the high deserts of the western USA, Christopher A Kiahtipes has training in environmental archaeology and palaeoecology. His research assesses vegetation responses to changes in climate, regional hydrology, and human land-use decisions using plant microfossils, with the overarching goal of integrating cultural and environmental histories to better contextualize the state of modern environments. His doctoral research reconstructed vegetation changes in the Central African Republic from the Iron Age until present. His postdoctoral work focused on developing a network of pollen records from inner Congo Basin peatlands proximal to known archaeological sites. As Associate Curator of the Natural History collections at the University of South Florida Library, Dr Kiahtipes works to develop archival and collections-based sources of data on environmental responses to climate change and conservation policy.

The central Congo Basin is home to the world’s largest tropical peatland complex, storing an estimated 29 petagram of carbon. Although the important role these peatlands play in the global carbon cycle is now recognized, very little is known about the biodiversity of these peatland ecosystems, including the vegetation associated with the peat. Here we investigate the plant diversity of six peatland sites along two contrasting river systems within the Democratic Republic of Congo: the Congo River, a white-water river, and the Ruki River, a black water tributary of the Congo River. In terms of species richness there is no difference between the Ruki and Congo peatland vegetation. Common species along both rivers include Raphia laurentii, R. sese, Guibourtia demeusei et Oubanguia africana. However, the abundance of species varies between sites.

Mr Kanyama Joseph

University of Kisangani, Democratic Republic of Congo

Mr Kanyama Joseph

University of Kisangani, Democratic Republic of Congo

Joseph Kanyama Tabu is a Lecturer and researcher at the University of Kisangani since 2010. He is the academic and hands-on theoretical supervisor of undergraduate students at the Faculty of Management of Renewable Natural Resources. PhD candidate at the same university since 2021, Joseph is undertaking research on the Congo Basin’s peatlands, in collaboration with the University of Leeds through the CongoPeat project. His studies are particularly focused on the understanding of tropical peatlands vegetation, with the aim of producing a new map of the central Congo peatlands vegetation. Regularly consultant, Mr Kanyama contributes with his expertise to several projects of peatlands data collection in DRC, as part of joint projects between the Ministry of the Environment and Sustainable Development (MEDD-DRC), the Peatlands Management Unit (UGT-DRC), the Japanese Cooperation Agency (JICA/JAFTA), CIFOR-SWAMPS program and the US Forest Service (USFS).

Mangrove ecosystems, which have experienced over 50% area loss globally, are now seen as crucial to the mitigation of many of today’s environmental challenges. Their ability to sequester and store large amounts of organic carbon in vegetation, soil and peat have made mangroves particularly well suited for restoration and conservation efforts targeted at mitigating or reducing CO2 emissions in certain countries. Mangrove loss rates have drastically decreased globally and gains in mangrove extent are reported worldwide, indicating successful restoration, protection or adaptation of the ecosystem to new areas. The Niger Delta region of Nigeria harbors the largest contiguous mangrove forest system in the world as well as Africa’s second largest extent of freshwater peatland forests. Contrary to global trends, the loss of mangrove ecosystems in Nigeria has increased since 2000. In addition to deforestation, large areas of endemic mangroves have been replaced by the invasive Nypa Palm. To date, the full extent of mangrove and peatland loss in Nigeria, as well as the causes and timing, have not been well quantified. Here, we use 40 years of historic satellite data coupled with in situ measurements, to map the extent, timing and causes of mangrove die off and degradation in Nigeria. We map current and historic mangrove extent using Landsat satellite data from 1984 through 2023. We use the recently released global mangrove height dataset at 12 m resolution to map height and calculate the biomass of mangrove forests. Finally, we estimate the total carbon stocks of the region (above, below and soil carbon) and estimate how much carbon previously stored in the mangrove ecosystem has been emitted or lost.

Dr Lola Fatoyinbo

NASA, US

Dr Lola Fatoyinbo

NASA, US

Dr Lola Fatoyinbo is a Forest and Coastal Ecologist who specialises in the use and application of Remote Sensing data for mapping and monitoring flooded ecosystems.  Her research combines in situ and Earth Observing data to measure forest type, carbon stocks, extent and degradation in forests, wetlands and coastal ecosystems, with a focus on Africa. As a research scientist at NASA’s Goddard Space Flight Center, Dr Fatoyinbo works on characterizing the vulnerability and response of mangroves to disturbances from land use and climate change, development of new instruments and missions, as well as Carbon monitoring and Biodiversity conservation. As a National Geographic Explorer, Dr Fatoyinbo is leading expeditions in Nigeria to uncover forested peatland locations and inform conservation applications. She is the recipient of 2024 Esmond B Martin Royal Geographical Society Prize for environmental conservation research. She holds a Bachelors degree in Biology and a PhD in Environmental Sciences from the University of Virginia. 

Peatlands provide critical ecosystem services, including habitat for biodiversity, water purification, and climate regulation. Tropical peatlands in Africa face significant knowledge gaps in occurrence and extent estimates, and lack policy initiatives related to conservation and sustainable management. This study expands a previous peatland inventory for the Angolan Highlands by extending the geographic scope to include the key Angolan Highlands Water Tower (AHWT). The inventory incorporates additional satellite- and terrain-based indices that capture unique phenological characteristics of peat, as well as geomorphological landscape features that play a mechanistic role in AHWT peat formation. Using an ensemble unsupervised classification approach, we present a probabilistic map of potential peat deposits, estimating that peatlands cover 11,168 km2 (2.94%) of the AHWT. This extent is comparable to the three major regions of tropical lowland peat across the globe — in the Congo's Cuvette Centrale, tropical islands of South East Asia, and Western Amazonia. The updated inventory can be used to guide conservation and estimate potential carbon stores for the region. Our methodological framework contributes to improved peatland mapping in the AHWT region, and can be adapted for other inaccessible areas with limited field data where the mechanisms leading to peat formation are similar.

Dr Mauro Lourenco

The Wild Bird Trust, South Africa

Dr Mauro Lourenco

The Wild Bird Trust, South Africa

Mauro Lourenco is a passionate geospatial scientist with expertise in peatlands, rivers, freshwater environments, and environmental monitoring. His current research focuses on natural water towers that contribute to major river basins across Africa. He is also using thermal and multispectral drones to assess peatland characteristics in the Angolan Highlands. Mauro completed his PhD in 2023, titled Peat Dynamics of the Angolan Highlands, at the University of the Witwatersrand in Johannesburg, South Africa. With experience working in Angola, Botswana, and South Africa, he has applied his advanced skills in geographical information systems and remote sensing technologies to address complex environmental challenges. Mauro is committed to sharing knowledge and collaborating with individuals from diverse backgrounds and disciplines to achieve meaningful and impactful scientific outcomes.

Tropical peatlands are a significant source of rising atmospheric concentrations of greenhouse gases, including methane. The Central Congo Basin is home to the world’s largest tropical peatland, but controls over greenhouse gas emissions are poorly understood. To address this, we collected surface peat samples from six sites featuring a mix of palm and hardwood dominated peatlands, incubating samples under flooded aerobic, flooded anoxic, and mesic conditions to quantify the extent to which hydrological regime regulates emissions of carbon dioxide, methane and nitrous oxide, and the extent to which the processes differ between contrasting plant communities. We found substantial differences in emissions between dominant vegetation types and in response to changes in hydrological regime. FTIR and nutrient analysis of surface peats indicated contrasting drivers between vegetation types. Peat samples collected to a depth of 1.5 m from two adjacent sites were also collected and incubated, with results indicating a surface peats dominant the production of greenhouse gases for peat derived from both vegetation types. Taken together our results indicate that hydrology, nutrient regime, and chemistry play a critical role in determining the balance of emissions from contrasting vegetation types in Central African peatlands.

Dr Nicholas Girkin

University of Nottingham, UK

Dr Nicholas Girkin

University of Nottingham, UK

Nicholas Girkin is an Assistant Professor in Environmental Science at the University of Nottingham. His research focusses primarily on the impacts of environmental change on global carbon and nitrogen dynamics, with a focus on tropical ecosystems, and the production and emission of greenhouse gases. His ongoing research is focussed on tropical wetlands, specifically in quantifying the impacts of land use and climate change on methane dynamics of major wetland and peatland ecosystems in Central Africa, and Central and South America, in collaboration with a range of local research partners. Alongside his work in tropical wetlands, he is Director of the University of Nottingham’s Centre for Sustainable Agricultural Systems, focussing on working directly with businesses to address global sustainability challenges in agriculture.

Insects play a wide range of roles in tropical forests, including several ecosystem processes which are particularly relevant in tropical peat-swamp forests such as herbivory and decomposition. The distinctive hydrological conditions which characterise tropical peatlands strongly influence forest structure and vegetative composition, however the consequences for insect diversity and ecological processes they mediate in these ecosystems are unclear. Here, I present results from a first assessment of the structure of insect communities in the central Congo peatlands, with a focus on herbivorous Lepidoptera (butterflies and moths) and aquatic Odonata (dragonflies and damselflies). By comparing patterns in community composition across palm- and hardwood-dominated swamp forests, I explore the factors contributing to insect diversity in these forests, and the potential consequences for biogeochemical cycling. Then, I assess the role of moths in nocturnal pollination within these peatland forest ecosystems, by constructing pollen-transport networks based on the identification of pollen loads. Together, these results demonstrate the central Congo peatlands host a low diversity of several functionally important insect groups, which are subject to a distinct set of ecological pressures. Whilst alpha diversity is low, peatland insect communities comprise several taxa thought to be peatland specialists, highlighting the need to wider characterisation and protection of Congolese peatland biodiversity.

Mr Charles Hackforth

University College London, UK

Mr Charles Hackforth

University College London, UK

Charlie is a finishing PhD student at University College London. His project aims to provide preliminary insight into the structure of insect communities in the central Congo peatlands, and to illuminate the functional roles of insects in these unique forested ecosystems, with a particular focus on pollinating moths. He has previously worked on the drivers of moth population trends in Panamanian rainforests, and on patterns of trait variation in insect species across urbanisation gradients in Germany. He holds a BA (Hons) in Biological Sciences from St Hilda’s College, University of Oxford.