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U.S. Forest Service

Diversity of Fens in the Mountains of California

The 2001 version of the Sierra Nevada Forest Plan Amendment, supplemented in 2004, highlighted fens to the attention of Pacific Southwest (Region 5) National Forests by requiring that inventories for “fens and bogs” be completed as part of botany project analysis and that fens be maintained, restored, preserved, and/or enhanced. Fens were determined to be particularly important for their biological diversity and as habitat for species of Sphagnum, Meesia, and other bryophytes. A bog and fen workshop occurred on the Sierra National Forest in June of 2002 that provided many people in California with their first glimpse of fens. Several fen workshops have occurred since that time with many people becoming interested in fens in the mountains of California.


Until 2002, only a handful of studies had identified peatlands in California. These included the Sagehen Valley north of Truckee on the Tahoe National Forest, Grass Lake on the Lake Tahoe Basin, and Inglenook Fen on the coast near Fort Bragg. Sagehen Creek watershed is in the Tahoe National Forest. Portions of Sagehen Valley are in a University of California Research Station. Grass Lake is on Luther Pass on the Lake Tahoe Basin Management Unit.

Kiln Fen. Kiln Fen, Sagehen Creek, Tahoe National Forest. Photo by Carl Wishner.

Grass Lake. Grass Lake, Lake Tahoe Basin Management Unit (LTBMU). Photo by LTBMU Staff.

Inglenook Fen is in MaKerricher State Park near Fort Bragg, California. It it the southernmost of a series of coastal fens running from Alaska southward. Inglenook Fen is the only coastal fen in California. This fen contains a unique assemblage of plants and insects of northern or high montane affinities. The fen is probably only 3,000 to 4,000 years old, but the community is probably a relic of the Pleistocene times. Inglenook fen was formed by an advancing shell of rich dunes blocking the acid drainage waters from the upland coniferous forest.

Inglenook Fen. Inglenook Fen.

Continuing Investigation

David Cooper and Evan Wolf investigated fens in the Southern Cascade and Sierra Nevada Mountains starting in 2003. Many fens from the Modoc to the Sequoia and Inyo National Forests were sampled at that time. Fens were only found at higher elevations, over 10,000 feet in elevation, and in the coolest portions of the forest in the south on both the Inyo and Sequoia National Forests. In the northern Sierra Nevada and Southern Cascade Range, fens can be found above 5,000 feet in elevation. There, the greater precipitation that allows for the development of ground water flow systems sufficient to support fens at lower elevations. According to Sue Weis, Botanist on the Inyo National Forest, the fens on the Inyo have mostly mosses and Carex. In contrast, many of the fens in northern California have an array of flowering plants.

Starting In 2002 and continuing to present day, fens are being investigated throughout many of the mountains of California. Emphasis was placed on the Sierra Nevada and Southern Cascade fens because of the Sierra Nevada Forest plan Amendment. Other forests in California are completing inventory work on fens as they can and budgets allow. Botanists working for the National Forests conducted many of these investigations.

Inventories of fens are currently being conducted on national forests in California to determine the types and extent of the fens. Detailed information is being collected to learn more about these unique ecosystems.

To date, fens have been found on the Klamath, Six Rivers, Shasta Trinity, Modoc, Lassen, Plumas, Tahoe, Lake Tahoe Basin, Eldorado, Stanislaus, Sierra, Sequoia, Inyo, and San Bernardino National Forests.

Map of California showing location of National Forests and fen locations. Fens identifed in California National Forests. Map produced by K. Sikes, February 2013. Updated May 13, 2014.

Photo Galleries

Explore the diversity of fens and the vegetation found on them in our California Fens photo galleries.

Next: Fen Conservation on National Forests in California…