Tucked into the borderlands of northern California and southern Oregon, the Klamath-Siskiyou Mountains are a place of raw, rugged beauty renowned for their biodiversity. The region is home to more species of conifer —32 of them—than any other temperate conifer forest in North America. The Klamath-Siskiyou ranks second in North America in terms of endemism (organisms found nowhere else in the world), and third in total species richness.
The region rises abruptly, creating a jumbled mass of rugged and diverse mountains, jagged peaks, wild rivers, and deep forest. Ancient and complex bedrock defines the Klamath-Siskiyou region as a whole. This seemingly haphazard patchwork of rock types creates and supports an unusually diverse and contrasting mosaic of habitat types, microclimates and plant diversity.
The following is a description of the Klamath-Siskiyou by the World Wildlife Fund. The Klamath-Siskiyou Region is on WWF’s “Global 200: The Most Outstanding and Representative Areas of Biodiversity.” For their complete description please visit the link below. This description was written in the 1990s, but is still relevant to this day.
“Temperate Coniferous Forest: Located in northwestern California and southwestern Oregon, complex terrain, geology, climate, and biogeographic history have created one of the Earth’s most extraordinary expressions of temperate biodiversity in the Klamath and Siskiyou Mountains. Although well known among biologists, few North Americans realize the uniqueness and importance of the species and communities in this ecoregion. Indeed, logging, mining, road building, and grazing continue to be intensive and pervasive threats to this area.
The Klamath-Siskiyou ecoregion is considered a global center of biodiversity (Wallace 1982), an IUCN Area of Global Botanical Significance (1 of 7 in North America), and is proposed as a World Heritage Site and UNESCO Biosphere Reserve (Vance-Borland et al. 1995). The biodiversity of these rugged coastal mountains of northwestern California and southwestern Oregon has garnered this acclaim because the region harbors one of the four richest temperate coniferous forests in the world (along with the Southeastern Conifer forests of North America, forests of Sichuan, China, and the forests of the Primorye region of the Russian Far East), with complex biogeographic patterns, high endemism, and unusual community assemblages. A variety of factors contribute to the region’s extraordinary living wealth. The region escaped extensive glaciation during recent ice ages, providing both a refuge for numerous taxa and long periods of relatively favorable conditions for species to adapt to specialized conditions. Shifts in climate over time have helped make this ecoregion a junction and transition zone for several major biotas, namely those of the Great Basin, the Oregon Coast Range, the Cascades Range, the Sierra Nevada, the California Central Valley, and Coastal Province of Northern California. Elements from all of these zones are currently present in the ecoregion’s communities. Temperate conifer tree species richness reaches a global maximum in the Klamath-Siskiyous with 30 species, including 7 endemics, and alpha diversity (single-site) measured at 17 species within a single square mile (2.59 km2) at one locality (Vance-Borland et al. 1995). Overall, around 3,500 plant species are known from the region, with many habitat specialists (including 90 serpentine specialists) and local endemics.
The great heterogeneity of the region’s biodiveristy is due to the area’s rugged terrain, very complex geology and soils (giving the region the name “the Klamath Knot” [A noteworthy book titled The Klamath Knot was written by David Rains Wallace in 1983]), and strong gradients in moisture decreasing away from the coast (e.g., more than300 cm (120in)/annum to less than 50 cm (20 in)/annum). Habitats are varied and range from wet coastal temperate rainforests to moist inland forests dominated by Douglas fir (Pseudotsuga menziesii), Pinus ponderosa, and P. lambertiana mixed with a variety of other conifers and hardwoods (e.g., Chamaecyparis lawsoniana, Lithocarpus densiflora, Taxus brevifolia, and Quercus chrysolepis); drier oak forests and savannas with Quercus garryana and Q. kelloggii; serpentine formations with well-developed sclerophyllous shrubs; higher elevation forests with Douglas fir, Tsuga mertensiana, Abies concolor and Abies magnifica; alpine grasslands on the higher peaks; and cranberry and pitcher plant bogs. Many species and communities have adapted to very narrow bands of environmental conditions or to very specific soils such as serpentine outcrops. Local endemism is quite pronounced with numerous species restricted to single mountains, watersheds, or even single habitat patches, tributary streambanks, or springs (e.g., herbaceous plants, salamanders, carabid beetles, land snails, see Olson 1991). Such fine-grained and complex distribution patterns means that any losses of native forests or habitats in this ecoregion can
significantly contribute to species extinction. Several of the only known localities for endemic harvestman, spiders, land snails, and other invertebrates have been heavily altered or lost through logging within the last decade, and the current status of these species is unknown (Olson 1991). Unfortunately, many invertebrate species with distribution patterns and habitat preferences that make them prone to extinction, such as old growth specialist species, are rarely recognized or listed as federal endangered species. Indeed, 83 species of Pacific Northwest freshwater mussels and land snails with extensive documentation of their endangerment were denied federal listing by the U.S. Fish and Wildlife Service in 1994 (J. Belsky, pers. comm. 1994).
Rivers and streams of the Klamath-Siskiyou region support a distinctive fish fauna, including nine species of native salmonids (salmon and trout), and several endemic or near-endemic species such as the tui chub (Gila bicolor), the Klamath small-scale sucker (Catostomus rimiculus), and the coastrange sculpin (Cottus aleuticus). Many unusual aquatic invertebrates are also occur in the region.” -WWF