PEATBOG: a biogeochemical model for analyzing coupled carbon and nitrogen dynamics in northern peatlands

摘要

Elevated nitrogen deposition and climate change alterthe vegetation communities and carbon (C) and nitrogen (N) cycling inpeatlands. To address this issue we developed a new process-orientedbiogeochemical model (PEATBOG) for analyzing coupled carbon and nitrogendynamics in northern peatlands. The model consists of four submodels, whichsimulate: (1) daily water table depth and depth profiles of soil moisture,temperature and oxygen levels; (2) competition among three plants functionaltypes (PFTs), production and litter production of plants; (3) decompositionof peat; and (4) production, consumption, diffusion and export of dissolved Cand N species in soil water. The model is novel in the integration of the Cand N cycles, the explicit spatial resolution belowground, the consistentconceptualization of movement of water and solutes, the incorporation ofstoichiometric controls on elemental fluxes and a consistentconceptualization of C and N reactivity in vegetation and soil organicmatter. The model was evaluated for the Mer Bleue Bog, near Ottawa, Ontario,with regards to simulation of soil moisture and temperature and the mostimportant processes in the C and N cycles. Model sensitivity was tested fornitrogen input, precipitation, and temperature, and the choices of the mostuncertain parameters were justified. A simulation of nitrogen deposition over40 yr demonstrates the advantages of the PEATBOG model in trackingbiogeochemical effects and vegetation change in the ecosystem.