Hotspot: California on the Edge
Klamath Siskiyou Ecoregion
Klamath-Siskiyou Wilderness
Wild and Rugged Sanctuary

The Klamath-Siskiyou Wilderness is one the richest temperate coniferous forests in the world. Much of the extraordinary biodiversity is due to the fact that the region escaped extensive glaciation during recent ice ages. This provided both a refuge for many species and long periods of favorable conditions for species to specialize. The mosaic of habitats in this region includes isolated “islands” of serpentine, which produce highly toxic soils. Many rare plants have special adaptations that allow them to thrive there. The Klamath-Siskiyou Wilderness also contains the largest concentration of un-dammed wild and scenic rivers in the United States. Over millions of years they have been responsible for cutting the steep, v-shaped valleys that shape the area’s rugged terrain.

Coho Salmon
Learn more about the Northern California Coast Coho Salmon >

Dry Serpentine Habitat
This area is famous for the amazing diversity of its serpentine-adapted plants, which includes many conifers. The Klamath-Siskiyou Wilderness has the highest diversity of conifers in the world with 35 different species.

Conifer richness also reflects the region’s sanctuary role. The Port Orford cedar and
Brewer’s spruce are relict species that survive only in the Klamath-Siskiyou. Millions of years ago they were more widespread, as evidenced by their scattered fossils.

Metamorphic rocks began as some other type of rock, but have been substantially changed by high temperature and pressure. In metamorphic rocks some or all of the minerals in the original rock are replaced, atom by atom, to form new minerals. Metamorphic rocks do not get hot enough to melt, or they would become igneous rocks. Enormous pressures squeeze the mineral grains in the rock making them long and flat. These rocks develop a layered structure that shows the direction of pressure. 

Schist has thin parallel layers of small mineral grains. Many of the original minerals have been altered into flakes that have been folded and can be seen by the naked eye.

Marble is formed from limestone, a sedimentary rock that formed at the bottom of evaporated seas and lakes. It is composed of calcite from the shells of ancient marine organisms.

Quartzite formed from its parent rock, sandstone, when it came into contact with deeply buried magmas. Quartzites are found in association with other metamorphosed sedimentary rocks such as schist and marble.

Rock and Roll
Most of the rocks in the Klamath-Siskiyou Wilderness consist of 200 million year old metamorphic rocks like schist, gneiss and serpentine. These deposits are divided into 4 roughly parallel belts with the oldest in the east and the youngest to the west.
Some granitic rock, about 150 million years old, intrudes into the older metamorphic rocks. Overlying these are glacial deposits from the Last Ice Age and marine sediments that are more than 60 million years old. The granitic peaks of the Trinity Alps began deep in the continental crust. The white Marble Mountains began as a deposit of sedimentary ooze in the Pacific Ocean.

Gneiss (pronounced "nice") is formed from sedimentary rock, such as sandstone, or igneous rock like granite. It is composed of thick, parallel bands of large-grain minerals like feldspar, mica and quartz.

Peridotite is a dense, coarse-grained igneous rock that can be the parent rock for serpentinite.

Serpentinite is California's state rock and was formed from oceanic crust. These seafloor rocks were compressed by subduction and elongated by movement along the San Andreas fault. Serpentinite can contain asbestos, a mineral that crystallizes in long, thin fibers.

Built from the Bottom Up
The rugged mountains in this region were formed when ancient seafloor collided with the western edge of North America.  There is hardly a mountaintop that didn’t start at the bottom of something else. The oldest rocks in the Klamath Knot are 225 million years old, the youngest are 65 million years old.

After millions of years of rising, twisting and being eroded by raging rivers, the result is a tangle of knife-edged peaks and steep canyons that connect the Cascade and Coast Ranges. Glaciers carved only the highest peaks and were limited to northern slopes.

A distinguishing geological feature of this region is the large surface exposure of oceanic crust known as the Trinity ophiolite. This oceanic crust was scraped off onto the continental shelf by the movement of tectonic plates.

Function at the Junction
The Klamath-Siskiyou’s biological diversity is due to a complex mosaic of habitats. This allowed species to survive here as changing climates eliminated populations elsewhere. 

The region is situated at the junction of 5 major biotic regions: the Great Basin, Coast Range, Cascade Range, Sierra Nevada and Great Central Valley, which all contribute to the rich biodiversity of the Klamath-Siskiyou area.

The Klamath-Siskiyou is home to many endemics, including 131 plant species. Over 60% of the 153 species of terrestrial and freshwater mollusks are found here and nowhere else.

The region was spared the volcanism of the nearby Cascades and the extensive glaciations that occurred in the Sierra Nevada. This created refuges for species that later became isolated in small patches of habitat. These relict species were once widespread, but now only survive in the Klamath-Siskiyou.

Meat-Eating Plants
Cobra lilies live on nutrient-poor soils and trap insects to supplement their diet.
Insects that land on the forked "tongue" are drawn into the plant's bulbous opening by the scent of nectar. Inside the pitcher are many small membranes called "fenestrations" that allow light to filter through the walls.

When insects try to leave, they fly up towards the light but are stopped by the slippery downward pointing hairs lining the walls inside the pitcher. Struggling to get out, they fall further down the pitcher into fluid at the bottom.  There, bacteria and other micro-organisms help break down the trapped insects into nutrients that can be absorbed by the plant.

Cobra lilies grow in sphagnum moss bogs or near freshwater springs. Their pitchers can reach a monstrous 40 inches (102 cm) or more in height, with heads the size of a softball. These plants are native to mountainous areas of northwestern California. Each cobra lily stalk is a modified leaf that folds in to form a tube.

The stalks twist away from each other as they grow which prevents a new plant from blocking an older pitcher plant's hood.  Short, stiff hairs on the forked-tongue of the hood point towards the opening of the pitcher and guide the insect inside.

Wet Serpentine Habitat
When serpentine soils are combined with natural springs or other sources of moisture, an even more unique environment is formed.
The mosaic of habitats in this region includes acidic bogs and seeps that form above serpentine deposits. These nutrient-poor soils host carnivorous plants like cobra lilies that attract, trap and digest insects and other small prey to supplement their diet.
 Loss of habitat, pollution and poaching all pose  serious threats to the survival of natural populations of serpentine endemics and carnivorous plants.

Serpentine - A Hard Rock to Live On
Much of the endemism found here is a direct result of harsh conditions created by the extensive areas of serpentine rock. About 20% of California’s endemic plants grow on serpentine soils. Most plants require nutrients like calcium, nitrogen and potassium which they get from soil. Few plants are able to grow in serpentine soils that contain a lethal combination of high magnesium and low calcium. Some serpentine soils also contain elements like nickel, platinum, mercury and chromium that prohibit the growth of many plant species.

East Meets West
Northern spotted owls, Strix occidentalis caurina, and old-growth forest preservation created intense struggles between loggers and environmentalists. Now, an introduced species, the barred owl, Strix varia, may pose the newest and greatest threat to the spotted owl’s survival.

Traditionally the northern spotted owl was the dominant owl in the forests of the western U.S., Canada and Mexico and barred owls presided over the eastern forests of the U.S. and Canada. However, today, territory once held by spotted owls, including forests in Northern California, is becoming home to families of barred owls.

spotted owl

Surveys in the eastern United States show that the preferred habitat of barred owls directly overlaps that of spotted owls.  In the past, the large un-forested midwestern prairies may have prevented westward migrations of barred owls.

As climatic conditions became more favorable, these birds began to extend their range west through northern Canadian forests and British Columbia. They now appear to be making their way south through the Pacific Northwest and into Northern California. A number of factors may have created migration corridors for the barred owl’s westward movement.

Global warming of just a few degrees may have forced barred owls northward into Canada where they found forests connecting east to west. Forests planted in the prairies may have created pathways to the west. Alternatively, barred owls may have been steadily progressing west for a long time and have only recently reached the Pacific Northwest.

Answers to these questions are being explored by Academy researcher Jack Dumbacher. It remains to be seen if the larger and more aggressive barred owl will ultimately
out-compete the northern spotted owl for territory and food.

Jack Dumbacher, an Academy ornithologist, is working with colleagues at the U.S. Fish and Wildlife Service and U.S. Forest Service to study and document how invasive barred owls are affecting populations of northern spotted owl.

Fire Suppression

Natural fire cycles were key contributors to the diversity of the Klamath Siskiyou area for millennia. Returning every 10-150 years, fires recycle nutrients, maintain diversity, renew fire-dependent species and leave burned out trees critical for wildlife.

Habitat Loss
Despite incredible biological richness, only 25% is relatively intact and just 10% is protected from logging. Clear-cutting seriously reduced old-growth forests and the only known habitats of some endemic species of invertebrates were lost.

Designated a World Heritage Site, a UNESCO Biosphere Reserve and an Area of Global Botanical Significance by the World Conservation Union, Klamath-Siskiyou has yet to be protected as a national park by Congress or a state park by California.

Much of the area is protected only by its remoteness and rugged terrain. The Yolla Bolly, Salmon Mountains, Trinity Alps, and Marble Mountains are designated Wilderness Areas, although mining is permitted. The protection the Endangered Species Act provides, has significant impact, especially in areas classified as old-growth forest.

What You Can Do
Experience Wilderness
The Klamath River provides a spectacular backdrop for kayaking, canoeing and rafting. Support conservation groups that are advocates for conservation issues in political arenas through membership and volunteering. To learn more, visit the Academy’s Naturalist Center on the second floor of this building.


Above: Mountains of the Klamath Siskiyou Wilderness

Coho Salmon

Dry serpentine habitat

Putting the Squeeze on Rocks

Klamath knot

Cobra lillies


spotted owl


Fire Suppression

Habitat Loss


What You Can Do