Agricultural Landuse Change Impacts on Bioenergy Production, Avifauna, and Water Use in Nebraska\u27s Rainwater Basin

Agriculture is an economically important form of landuse in the North American Great Plains. Since 19th Century European settlement, conversion of grasslands to rowcrops has increased food and bioenergy production, but has decreased wildlife habitat. Future agricultural landuse changes may be driven by alternative energy demands and regional climatic changes. Landuse change and its drivers could affect bioenergy production, wildlife populations and natural resources, and considering the potential impacts of impending changes in advance could assist with preparations for an uncertain future. This study addressed how the conversion of marginally productive agricultural lands in the Rainwater Basin region of south–central Nebraska, U.S.A. to bioenergy switchgrass (Panicum virgatum) might impact ethanol production, grassland bird populations and agricultural groundwater withdrawals. This study also used multi–model inference to develop predictive models explaining annual variation in springtime wetland occurrence and flooded area in the Rainwater Basin. Results suggest that producing adequate biomass for year round cellulosic ethanol production from switchgrass and residual maize (Zea mays) stover within existing starch–based ethanol plant service areas is feasible at current feedstock yields, removal rates and bioconversion efficiencies. Throughout the Rainwater Basin, the replacement of marginally productive rowcrop fields with switchgrass could increase ethanol production, conserve groundwater and benefit grassland birds under novel future climatic conditions. However, converting Conservation Reserve Program (CRP) grassland to switchgrass could be detrimental to grassland bird populations. Predictive wetland inundation models suggest that springtime wetland inundation in the Rainwater Basin is a complex process driven by individual wetland characteristics, surrounding landuse and local weather events. The impacts of future climatic and landuse changes in the Rainwater Basin and surrounding Great Plains is ultimately likely to depend on which forms of alternative landuse are adopted and on how intensely change occurs. Advisor: Craig R. Alle