Serpentine Barrens
Serpentine barrens represent the most xeric natural community that occurs in the serpentine environs of the Klamath-Siskiyou region. Two types of serpentine barrens have been described.
- Jimerson (et al. 1995) described serpentine barrens as bare soil, gravels and rock supporting a sparse vegetative cover of Idaho fescue and low lying shrubs including Siskiyou mat (Ceanothus pumilus) and common juniper (Juniperus communis).
- Kruckeberg (1999) characterizes serpentine barrens as containing no woody species but a very sparse herbaceous cover of xeromorphic annuals and perennials.
A serpentine barrens inclusion in a Jeffrey pine (Pinus jeffreyi) shrubland. Photo by Susan Erwin.
In this view of a Slate Mountain serpentine barrens, note the unusually large amount of forb and shrub cover.
Serpentine barrens occur as small, one to two acres or larger, openings surrounded by serpentine conifer or woodland communities. Outcrops of exposed bedrock are commonly found in nested in the barren community.
Serpentine barrens represent the harshest serpentine community. The soils are extremely thin and rocky lying directly upon the parent material (most commonly serpentinite). These soils contain a very high amount of magnesium, very low amount calcium and other soil nutrients and may have significant amounts of nickel and other heavy metals. Serpentines barrens occur on south to southwest to west aspect, which is characterized by a warmer temperature than the surrounding vegetation and highly xeric soils.
The environmental extremes of serpentine barrens support a very high percentage of plants considered narrow endemics. Kruckeberg (1999) attributes this high percentage of narrow endemics to the severe chemical and physical extremes of the serpentine barrens and their discontinuity in the landscape. In fact, serpentine barrens contain more narrow endemic plants than any other serpentine natural community in the Klamath-Siskiyou region; and as such, the most rare plants (Jimerson, et. al. 1995). Represented plant genera associated with the harshest of serpentine communities include Arabis, Eriogonum, Sedum, and Streptanthus.
Stebbin's madia (Madia stebbinsii). Note the silver hairs on the leaves and stems of this wildflower. The silvery hairs reflect sunlight that allows the plant to better conserve moisture. Photo by Dr. Dean William Taylor, Jepson Herbarium.
Photo Gallery
Our thanks to CalPhotos and its many contributors for many of the pictures in this photo gallery.
Asclepias solanoana. Photo by Shauna Hee.
Asclepias solanoana. Photo by Shauna Hee.
Barrens in fog. Photo courtesy of Six Rivers National Forest.
Eriogonum libertini. Photo by Susan Erwin.
Fritillaria glauca. Photo by Susan Erwin.
Minuartia rosei. Photo copyright T. Spira and CNPS.
Orobanche fasciculata. Photo by Susan Erwin.
Pyroxinite barrens. Photo by Susan Erwin.
Pyroxinite barrens. Photo by Susan Erwin.
Senecio greenei. Photo by Susan Erwin.
Resources and References
- Jimerson, T. M. and L. D. Hoover, E. A. McGee, G. Denitto and R. M. Creasy. 1995. A Field Guide to Serpentine Plant Associations and Sensitive Plants in Northwestern California. USDA Forest Service, Pacific Southwest Region, R5-ECOL-TP-006.
- Kruckeberg, A. R. 1999. Serpentine barrens of western North America. pp. 309-321, In Anderson, R. C., J. S. Fralish and J. M. Baskins, eds. Savannas, Barrens, and Rock Outcrop Communities of North America. Cambridge University Press.