PVN 1.0: using dynamic PFTs and restoration scenarios to model CO2 and CH4 emissions in peatlands

Abstract. Peatlands are the world’s largest terrestrial carbon store. Despite covering only 3 % of the planet’s land surface, peatlands store 30 % of the planet’s terrestrially available carbon. The Dutch government's 2019 National Climate Agreement committed to reduce the contribution of peatlands to total national Dutch greenhouse gas (GHG) emissions, by 1 Mton CO2 per year (20 %) until 2030. Countries with similarly degraded peatlands are likely to face similar commitments in the coming years. Restoration (or rewetting) is a proposed solution to reduce land subsidence and increase carbon sequestration in agricultural peatlands but is often accompanied by large CH4 emissions. Whilst, previous studies have investigated whether singular plant types impact the GHG emissions of peatlands, few (or no) studies have investigated the impact of plant composition on GHG emissions in peatlands. To assess the impact of dynamic vegetation on subsequent GHG fluxes in peatlands, we developed a new model, Peatland-VU-NUCOM (PVN). This is the second process-based model to date, capable of simulating dynamic vegetation, CO2, and CH4 emissions in peatlands. The new PVN model simulates CH4 and CO2 fluxes in relation to the plant community composition. The PVN model includes plant competition, CH4 diffusion, ebullition, root, shoot, litter exudate production, below-ground decomposition, and aboveground moss development, under changing water table and climatic conditions. The model was compared against observational data collected at two sites in the Netherlands. These results showed that plant communities impact net GHG emissions. This is the first time that a peatland emissions model is able to investigate the role of re-introducing peat forming vegetation on subsequent GHG emissions. We also found that the initial plant community influenced the potential for harvest events to reduce GHG emissions. These results indicated that plant community restoration is a critical component of peatland restoration.