Climate Moisture Index
A BIOCLIM+ raster map of the continental U.S.A. containing 30-year climate moisture index averages (1981-2010) was downloaded from the CHELSA (Climatologies at high resolution for the Earth’s land surface areas) database (Brun et al., 2022). The climate moisture index is calculated as the difference between mean annual precipitation and mean potential evapotranspiration and, when negative, represents the availability of water as a limiting resource in dry regions such as prairies.