Complex interactions between biotic and abiotic factors have encouraged and nurtured biodiversity in the Klamath Mountain region over millions of years. The region is a botanical museum, hiding relicts of epochs gone by called paleoendemics and also a cradle, promoting the adaptive evolution of new species called neoendemics. Complex climate and soils nurture microsites which, in essence, incubate biodiversity. The area also has a central location and continuity with other mountain ranges along the Pacific Slope. Across this landscape, a mosaic of habitats mix at a crossroads of five biotic regions—the Cascades, Coast Range, Great Basin, Central Valley, and Sierra Nevada—each helping to define the Klamath Mountains.

Within geologic boundaries, defining these complex habitat mosaics, there are 3,540 vascular plant taxa (species, subspecies, and varieties) of plants and up to 38 species of conifers, depending on where one delineates the region (Sawyer 2006). In addition to plants, the region holds exceptional diversity in amphibians, mammals, and birds. The conifers represent a manageable means for comprehending all biodiversity of the region.