Modelling dissolved organic carbon dynamics in a rehabilitated Sphagnum-dominated peatland

Sphagnum-dominated peatlands represent a major stock of the global soil carbon (C) pool (Gorham, 1991). Dissolved organic carbon (DOC) exports through runoff and leaching could reduce their potential C storage function (Billett et al., 2004) and impact downstream water quality (Ritson et al., 2014). DOC dynamics in peatlands is strongly controlled by site hydrology, especially by water table depth (WTD), and disturbances such as drainage can lead to increased DOC export (Strack et al., 2008). In addition, hydrological restoration (e.g. rewetting) can be undertaken to restore peatland functioning with a potential impact on DOC dynamic and export. While changes in DOC net production resulting from WTD drawdown can be assessed through field studies, the contribution of DOC production and consumption are more difficult to evaluate (Strack et al., 2008). In this case, process-based biogeochemical models simulating DOC dynamics combined with hydrological models adapted to peatlands specific settings are relevant tools to study factors controlling DOC production and consumption in such environments. In this study a module simulating DOC production and consumption was added to an existing WTD dependent hydrological model. The model was applied to two sites of a peatland, one of them having experienced rewetting. The objective is to identify factors controlling DOC dynamics and to assess the impact of rewetting on DOC export in a Sphagnum-dominated peatland.