Predicted avian responses to bioenergy development scenarios in an intensive agricultural landscape

Abstract

Conversion of native prairie to agriculture has increased food and bioenergy production but decreased wildlife habitat. However, enrollment of highly erodible cropland in conservation programs has compensated for some grassland loss. In the future, climate change and production of second-generation perennial biofuel crops could further transform agricultural landscapes and increase or decrease grassland area. Switchgrass ( Panicum virgatum ) is an alternative biofuel feedstock that may be economically and environmentally superior to maize ( Zea mays ) grain for ethanol production on marginally productive lands. Switchgrass could benefit farmers economically and increase grassland area, but there is uncertainty as to how conversions between rowcrops, switchgrass monocultures and conservation grasslands might occur and affect wildlife. To explore potential impacts on grassland birds, we developed four agricultural land-use change scenarios for an intensively cultivated landscape, each driven by potential future climatic changes and ensuing irrigation limitations, ethanol demand, commodity prices, and continuation of a conservation program. For each scenario, we calculated changes in area for landcover classes and predicted changes in grassland bird abundances. Overall, birds responded positively to the replacement of rowcrops with switchgrass and negatively to the conversion of conservation grasslands to switchgrass or rowcrops. Landscape context and interactions between climate, crop water use, and irrigation availability could influence future land-use, and subsequently, avian habitat quality and quantity. Switchgrass is likely to provide higher quality avian habitat than rowcrops but lower quality habitat than conservation grasslands, and therefore, may most benefit birds in heavily cultivated, irrigation dependent landscapes under warmer and drier conditions, where economic profitability may also encourage conversions to drought tolerant bioenergy feedstocks.