Conversion of species' critical habitats and ranges in the U.S.: Contributions from ethanol production and other factors.

Biofuels play a key role in reducing greenhouse gas (GHG) emissions and enhancing energy security. Since the 1970s, U.S. biofuel policies have positioned the country as a leading ethanol producer. The Renewable Fuel Standard (RFS), introduced in 2005, significantly increased ethanol production but also raised concerns about its environmental impact, particularly land use changes. This study examines the extent of land use changes associated with ethanol production, identifies the species affected by ethanol-induced land conversions, and leverages existing econometric studies to separate the effect of the RFS Program from other contributing factors. Using USGS Land Change Monitoring, Assessment, and Projection (LCMAP) data, empirical analyses, and U.S. Fish and Wildlife Service habitat layers, we evaluate the extent of cropland expansion driven by ethanol production and its effect on listed species from 2003 to 2014. Our analysis estimates that 20.8 million acres were converted to cropland, with a peak expansion of 2.98 million acres in 2010, primarily along the edges of the U.S. rainfed region. Of this, 0.23 million acres overlapped with critical habitats of 118 listed species, with 18 species losing at least 10,000 acres or 10 % of their habitat. This loss could disrupt essential ecosystem services, highlighting the urgent need for conservation efforts. Additionally, ethanol-related factors contributed to 5.85 % of cropland expansion, with the RFS accounted for just 0.34 %. Other key drivers included rising crop prices, land rent, livestock production, urbanization, and broader land-use pressures. These findings offer insights for policymakers to evaluate both biofuel and non-biofuel policies in mitigating land conversion impacts on threatened and endangered species.