Elevation: Elevation and life zones are strong drivers of biodiversity patterns particularly in mountainous regions where lowland habitats differ dramatically in composition and structure from high elevation habitats. The map shown provides a standard set of elevation zones for national context but because species-elevation relationships vary spatially across the US, each study region developed its own set of elevation/life zone thresholds as appropriate for the ecology of the region. To see the elevation zones used in each study region, and for detail on the species-elevation relationships, we encourage users to read the report corresponding to their region of interest: Eastern US, Great Lakes and Tallgrass Prairie, Great Plains, Lower Mississippi and Ozarks, Rocky Mountains and Desert Southwest, Pacific Northwest, California