The Southeast Deserts Bioregion (desert bioregion) occupies the southeastern 27% of California (11,028,300 ha, 110,283 km2 or 27,251,610 ac) (Miles and Goudy 1997) (Map 18.1). The desert bioregion is within the basin and range geomorphic province of western North America, and includes two ecoregional provinces comprised of five ecological sections. The American Semi-Desert and Desert Province (warm deserts) includes the Mojave Desert, Sonoran Desert, and Colorado Desert sections in the southern 83% of the desert bioregion. The Intermountain Semi-Desert Province (cold deserts) includes the Southeastern Great Basin and Mono sections in the northern 17% of the desert bioregion. [Map 18.1] The desert bioregion is characterized by isolated mountain ranges with steep slopes separated by broad basins containing alluvial fans, lava flows, dunes, and playas. Elevations range from -86 m (-282 ft) below sea level in Death Valley, to 4,342 m (14,246 ft) above sea level in the White Mountains. Soil taxa range widely from hyperthermic or thermic, aridic Aridisols and Entisols in the Colorado, Sonoran, and Mojave Desert sections, to thermic, mesic, frigid, or cryic, aridic, xeric, or aquic Alfisols, Aridisols, Entisols, Inceptisols, Mollisols, and Vertisols in the Mono and Southeastern Great Basin sections (Miles and Goudy 1997). This wide range in geomorphology and soil conditions translates into variable vegetation and fuel types, which include arid shrublands and semi-arid shrublands, grasslands, woodlands, and forests.