Environmental controls over greenhouse gas dynamics of tropical peatlands of the Central Congo Basin

The central Congo Basin hosts the world's largest tropical peatland complex, storing 29.0 Pg of carbon, the equivalent to three years of global CO₂ emissions. These peatlands are significant natural sources of greenhouse gases (GHGs), including CO₂, CH₄ and N₂O, but the environmental controls on their emissions remain poorly understood. To address this, we collected surface peat samples from six regional landscapes, spanning palm- and hardwood-dominated sites, and incubated them under three hydrological regimes: flooded aerobic, flooded anoxic and mesic (aerobic and no surface water). This allowed us to quantify how hydrology and peat chemistry (carbon, nutrients and organic chemistry) influence GHG dynamics. We observed strong differences in GHG production between vegetation types, and high sensitivity to hydrological change. Using random forest models, we assessed 27 potential drivers of GHG fluxes, identifying distinct controls across GHGs and hydrological regimes. Incubation of deeper peat samples (up to 1.5 m) highlighted that surface layers dominate peat GHG production. Taken together, our findings demonstrate that hydrology, vegetation, nutrients and peat organic chemistry shape regional GHG emissions, driving substantial spatial variability. Changes to peatland hydrology, for example from land use or climate change, could significantly shift GHG balances, with important implications for global climate feedbacks. A French translation of this abstract is available in the supplementary material.