Including hydrological self-regulating processes in peatland models: Effects on peatmoss drought projections.

Nijp, J.J.; Metselaar, K.; Limpens, J.; Teutschbein, Claudia; Peichl, M.; Nilsson, Mats; Berendse, F.; Zee, S.E.A.T.M. van der


The water content of the topsoil is one of the key factors controlling biogeochemical processes, greenhouse gas emissions and biosphere – atmosphere interactions in many ecosystems, particularly in northern peatlands. In thesewetland ecosystems, thewater content of the photosynthetic active peatmoss layer is crucial for ecosystem functioning and carbon sequestration, and is sensitive to future shifts in rainfall and drought characteristics. Current
peatland models differ in the degree in which hydrological feedbacks are included, but how this affects peatmoss drought projections is unknown.
The aimof this paperwas to systematically testwhether the level of hydrological detail inmodels could bias projections ofwater content and drought stress for peatmoss in northern peatlands using downscaled projections for
rainfall and potential evapotranspiration in the current (1991–2020) and future climate (2061–2090). We considered fourmodel variants that either include or exclude moss (rain)water storage and peat volume change, as these are two central processes in the hydrological self-regulation of peatmoss carpets.Model performance was validated using field data of a peatland in northern Sweden.
Includingmosswater storage aswell as peat volume change resulted in a significant improvement ofmodel performance, despite the extra parameters added. The best performance was achieved if both processes were.