Historical Land Use Change Impacts in the Great Plains

Human activity and climate change have had a big impact on the ecosystem dynamics of managed and unmanaged terrestrial systems. The impact of human activities and climatic changes have been observed using numerous field experiments and computer models are capable of simulating the impact of climatic and land use changes on terrestrial systems. This talk will demonstrate how human land use changes during the last 150 years in the US Great Plains have altered carbon balance and trace gas fluxes for the region. DayCent model results suggest the 30 to 50% of the soil carbon has been lost from the soils and N2O fluxes have been increased 10 to 50% for different parts of the region. Plant production has also been greatly changes with decreases occurring in the dryland cropping systems and increases associated with irrigated cropping systems. The talk will also project the potential future impact of biofuel production cropping systems on US Agricultural systems. Biofuel cropping systems have the potential to alter ecosystem dynamics of agricultural systems in both positive and negative ways. Conversion of existing agricultural land into biofuel production systems generally has a positive impact of reducing net greenhouse gas fluxes, however, conversion of conservation reserve program land and undisturbed natural systems into biofuel production systems can greatly reduce the potential positive impact of biofuel systems on reducing greenhouse gas fluxes.