1. Linking Economic Models to Ecosystem Models: Biofuel Examples Bill Parton Steve Del Grosso Sarah Davis Bruce McCarl Steve Williams Steve Ogle

2. Outline  Ecosystem Models DayCent model description & testing DayCent model description & testing EPIC, DNDC, BIOM-BGC EPIC, DNDC, BIOM-BGC  Linking to Economic Models Fully linked Fully linked Economic → Ecosystem Economic → Ecosystem Ecosystem → Economic Ecosystem → Economic  Biofuel Ecosystem Model Results Pennsylvania Pennsylvania Illinois Illinois  Conclusions

8. Fully Linked Economic and Ecological Models Economic Model Land Use Change and Ag Management Optimal Land Use Practice Ecological Model Assessment NPP Greenhouse Gas Fluxes

9. Advantages All land use options can be assessed All land use options can be assessedDisadvantages Complex model Complex model Excess computer time Excess computer time Vulnerable to errors Vulnerable to errors

10. Economic Models Drive Ecological Models  Use FASM U.S. Agricultural Model to predict biofuel land use change Expansion of ag land into: Expansion of ag land into: 1.CRP 2.Grassland 3.Forests

11. Economic Models Drive Ecological Models  DayCent Model simulated ecosystem response Plant production Plant production N 2 O fluxes N 2 O fluxes Soil C changes Soil C changes  Change in crop acreage Corn vs. Soybean vs. Wheat Corn vs. Soybean vs. Wheat

14. Grassland/Degraded Land

15. Ecological Models Drive Economic Models  Use ecological models to drive response surfaces used in economic models N 2 O vs. Fertilizer N 2 O vs. Fertilizer Yield vs. Fertilizer Yield vs. Fertilizer Soil C vs. Land Use and Fertilizer Soil C vs. Land Use and Fertilizer

16. Response Surface Modeling

21. Global Model Results

26. Beach, R.H., B.J. DeAngelo, S. Rose, C. Li, W. Salas, S.J. DelGrosso. 2008. Mitigation potential and costs for global agricultural greenhouse gas emissions. Agricultural Economics 38: 109–115.

27. Biofuel Crop Specific Greenhouse Gas Budget  Pennsylvania Switchgrass Switchgrass Corn/Soybean Corn/Soybean Popular Popular  Illinois/Iowa Switchgrass Switchgrass Miscanthus Miscanthus

28. Adler, P.R., S.J. Del Grosso, and W.J. Parton. 2007. Life cycle assessment of net greenhouse gas flux for bioenergy cropping systems. Ecol. Appl. 17(3):675–691.

29. Greenhouse gas sources and sinks from bioenergy cropping systems in the near-term Adler, P.R., S.J. Del Grosso, and W.J. Parton. 2007. Life cycle assessment of net greenhouse gas flux for bioenergy cropping systems. Ecol. Appl. 17(3):675–691.

30. Observed and DAYCENT N 2 O for Biofuel Cropping Systems in Pennsylvania

32. S. C. Davis

36. Summary  Fully linked models are difficult to use  Offline linking of models works well  Net greenhouse gas balances are a function of: Specific biofuel crop Specific biofuel crop Perennial vs. annualPerennial vs. annual Land use prior to start of biofuel crop Land use prior to start of biofuel crop Existing croplandExisting cropland CRP/mature grassland?CRP/mature grassland? Tillage and fertilizing practice Tillage and fertilizing practice