Insights into Holocene peat decomposition, vulnerability and vegetation change in the central Congo Basin

Central Africa's hydroclimate has experienced significant fluctuations over the past 20 000 years, having a marked impact on both humans and ecosystems. A drying trend between approximately 5000 and 2000 years ago caused peat decomposition, carbon release and a change in forest composition in the world's largest tropical peatland. Here, we investigate the nature of the peat decomposition and its impact on the peat swamp forest at four sites in the central Congo Basin peatlands. Attenuated total reflection Fourier transform infrared spectroscopy, carbon-to-nitrogen ratios (C/N) and age-depth chronologies show that peat decomposition was characterized by the preferential degradation of aromatic compounds, resulting in major peat loss dated to between 7500 and 800 cal yr BP. Distinct site-specific responses, unique to interfluvial versus river floodplain peatlands, were probably shaped by the interaction of regional drying, local hydrological conditions and different patterns of vegetation succession. While our results reflect differing hydrological resilience, all sites showed substantial peat loss and a change in forest composition, underscoring the Congo peatlands' vulnerability to hydroclimate change. This provides important initial insights into the mechanisms of peat loss-knowledge that is necessary for peatland protection and restoration. A French translation of this abstract is available in the supplementary material. A French translation of this abstract is available in the supplementary material. This article is part of the discussion meeting issue 'African tropical peatlands: function, value and vulnerability'.