The Northeastern California Plateaus Bioregion Science Synthesis: Background, rationale, and scope [Chapter 1.1]

Situated in Northeastern California, the Lassen National Forest spans 1.2 million acres (485,625 ha) and the Modoc National Forest another 1.65 million acres (667,730 ha), mainly in Lassen and Modoc Counties, but also across portions of Butte, Plumas, Shasta, Siskiyou, and Tehama counties. A unique blend of geology, topography, elevations from 2,000 to 14,000 feet (610 to 4,270 m), and climate have fostered immense biodiversity within this area. On the western edge of these national forests, the Cascade Range, characterized by steep changes in elevation and a Mediterranean climate (cool, wet winters and warm, dry summers), draws out the precipitation from Pacific storms, leaving a rain shadow to the east. The result is a rich vegetation gradient of mixed-conifer forest, dry pine forests, oak savannahs, juniper woodlands, and sagebrush steppe. In addition, fire, promoted by the Mediterranean climate, further stimulates a mosaic of vegetation across the landscape that supports a wide variety of fauna. For more detailed descriptions of this area, see Gonzales and Hoshi (2015a, b), Riegel et al. (2006), and Skinner and Taylor (2006).