Modelling CO2 and CH4 fluxes from drained and natural peatlands with the PEATLAND-VU model

Draining peatlands results in oxic soil conditions that causes microbial oxidation of peat. Drained peatlands are a large source for CO2 emissions, contributing 2-5% to the total anthropogenic greenhouse gas emissions. Understanding processes that contribute to peat oxidation are useful to simulate, predict and project CO2 emission in different environmental conditions. In wet conditions, soil is anoxic, which leads to an increase in methane (CH4) emission. Wetlands, including peatlands, are the largest natural source of CH4. Weather conditions, water table height, substrate availability, and vegetation type play a crucial role in the amount of CH4 that is emitted. The dynamic of CH4 production and oxidation, driven by the above mentioned factors, is complex. Nevertheless, for both CO2 and CH4, it is essential to be able to simulate these fluxes with a mechanistical model for monitoring and predicting greenhouse gas emission from peatlands. PEATLAND-VU is a 1D process based model, consisting of four submodels for 1) soil physics (water table, soil temperature and soil moisture), 2) biomass production, 3) CH4 production, oxidation and transport (diffusion, ebullition and plant transport), and 4) CO2 production. Here, CO2 production is represented as the sum of decomposition from different soil organic matter (SOM) pools, like litter, root exudates, microbial biomass, and peat. We calibrated the PEATLAND-VU model for two intensively used drained peat meadows and a wet Sphagnum-reed peatland in the Netherlands. These sites have 2-4 years of CO2 flux and CH4 flux (Sphagnum-reed peatland only) data. In our presentation we will show that the model performed well for simulating CO2 and CH4 fluxes. We will focus on the contribution of peat oxidation to the total CO2 emission, and show results of different water table management and future climate scenarios. Furthermore, for the Sphagnum-reed peatland the modelled CH4 production, CH4 oxidation, and the transport pathways resulting in the net CH4 flux will be discussed.