"Modelling a Global Biogeochemical Nitrogen Cycle Model in Terrestrial Ecosystems" 

Lin Bin-Le

National Institute of Advanced Industrial Science and Technology

Ecological Modelling,  (2002)

---

Abstract

An integrated global model developed mechanistically based on nitrogen transformation processes and nitrogen fluxes between the terrestrial biosphere and the atmosphere is described in this paper. This model was designed in conjunction with our previous global carbon model on the compartments of vegetation and organic-soil, a third compartment, inorganic-soil, comprising ammonium and nitrate was also incorporated. 

We divided the global terrestrial biosphere into 60,156 grid cells, each cell being 0.5° latitude by 0.5° longitude in size, whereas we simplified the atmosphere by regarding it as a well-mixed reservoir. Each grid cell was fixed as one of the five types of ecosystems: tropical forest, temperate forest, boreal forest, crops/grassland, or no vegetation (desert, ice). Geographical information system (GIS) data on climate, soils, and vegetation for each grid cell was used to drive the model in monthly time steps. 

Almost all of the key processes governing nitrogen cycling in the natural ecosystem were defined based on their respective mechanisms and specific relationships to environmental factors, then integrated into a highly aggregated dynamic model. Parameters required by the model were derived from published information or determined by model calibrations such as curve fitting. We therefore can conclude at this stage that the basic framework of a global biogeochemical nitrogen cycle, which can be used as a tool for quantitative evaluation of anthropogenic disturbances, has been developed.

Keywords

Modelling, Global biogeochemical nitrogen cycle, Nitrogen storage, Vegetation, Soil, Organic nitrogen, Inorganic nitrogen, Geographical information system, Ecosystem model, Anthropogenic disturbances