Project leaders: Dr. John Couwenberg (University of Greifswald), Prof. Dr. Gerald Jurasinski (University of Greifswald), Prof. Dr. Bernd Lennartz (University of Rostock)

Contributing to the Overarching Research Question 2, S2 will quantify four key ecosystem functions of peatlands, i.e. the storage of C, nutrients, water and information, all of which are related to services to humans. In S2 we develop a conceptual model of fen peat formation (KAARLO), describing peat growth after rewetting, explicitly considering that rewetted peatlands are novel ecosystems (Kreyling et al. 2021). In contrast to pristine peat, rewetted, formerly drained fen peat is characterized by degraded peat horizons, which are modified upon rewetting by hydraulic/mechanical forces and biological processes such as root growth and microbiological activity. The accumulation of plant litter or organic mud and eventually fresh peat on top of the degraded peat horizon is the second central process resulting from rewetting. Both the degraded and the newly developed peat horizons together form a novel type of peat. In S2 we characterize and quantify multiple processes that control the storage functions of this peat. The conceptual model describes peat formation at the pedon-scale including hydro-physical and geochemical properties with depth and time after rewetting as a function of state variables, such as water table, concentrations of relevant elements (C, N, sulur, phosphorus) and plant community composition. Resulting transport, exchange, and biogeochemical processes as well as feedback-loops impacting the development of displacement peat will be characterized.