Natural Resources, School of


Date of this Version



In: Mark A. Liebig, Alan J. Franzluebbers, & Ronald F. Follett, eds. Managing Agricultural Greenhouse Gases (2012), pp 309-323. Academic Press/Elsevier. doi:10.1016/B978-0-12-386897-8.00018-8


U.S. government work


The General Ensemble Biogeochemical Modeling System (GEMS) (Liu, 2009; Liu et al., 2004c) was developed to integrate well-established ecosystem biogeochemical models with various spatial databases for the simulations of biogeochemical cycles over large areas. Figure 18.1 shows the overall structure of the GEMS. Some of the key components are described below.

General Ensemble Biogeochemical

Modeling System (GEMS) 310

Multiple Underlying Biogeochemical Models 310

Monte Carlo Simulations 311

Model Inputs: Management Practices and Others 311

Model Outputs 311

Data Assimilation 311

Simulation of Agricultural Practices: EDCM as an Example 312

Net Primary Production (NPP) and Improvements in Crop Genetics and Agronomics 312

Soil Carbon Dynamics 312

Impacts of Soil Erosion and Deposition 313

CH4 and N2O Fluxes 313

Study Areas and Modeling Design 314

Study Areas 314

Nebraska Eddy Flux Tower Sites 314

Regional Applications: Mississippi Valley and Prairie Potholes 315

Modeling Design 315

Results 316

Impacts of Management Practices on SOC at Site Scale 316

Quantification of Regional Carbon Stocks and GHG Fluxes 317

Prairie Pothole Region 317

Mississippi Valley 319

Discussion 320