Natural Resources
Conservation Service
Ecological site F022AC008CA
Cryic Volcanic Mountain Slopes
Accessed: 12/05/2024
General information
Approved. An approved ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model, enough information to identify the ecological site, and full documentation for all ecosystem states contained in the state and transition model.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 022A–Sierra Nevada and Tehachapi Mountains
Major Land Resource Area 22A, Sierra Nevada Mountains, is located predominantly in California and a small section of western Nevada. The area lies completely within the Sierra Nevada Section of the Cascade-Sierra Mountains Province. The Sierra Nevada range has a gentle western slope, and a very abrupt eastern slope. The Sierra Nevada consists of hilly to steep mountains and occasional flatter mountain valleys. Elevation ranges between 1,500 and 9,000 ft throughout most of the range, but peaks often exceed 12,000 ft. The highest point in the continental US occurs in this MLRA (Mount Whitney, 14,494 ft). Most of the Sierra Nevada is dominated by granitic rock of the Mesozoic age, known as the Sierra Nevada Batholith. The northern half is flanked on the west by a metamorphic belt, which consists of highly metamorphosed sedimentary and volcanic rocks. Additionally, glacial activity of the Pleistocene has played a major role in shaping Sierra Nevada features, including cirques, arêtes, and glacial deposits and moraines. Average annual precipitation ranges from 20 to 80 inches in most of the area, with increases along elevational and south-north gradients. Soil temperature regime ranges from mesic, frigid, and cryic. Due to the extreme elevational range found within this MLRA, Land Resource Units (LRUs) were designated to group the MLRA into similar land units.
LRU "C" Northern Sierra Subalpine: Elevations are typically between 7,800 and 9,800 feet. The frost free period is between 30 and 90 days, MAAT is between 35 and 44 degrees, MAP is between 45 and 65 inches. Soils are typically cryic, but frigid soils may occur at lower elevations on southern aspects. Forests are dominated by whitebark pine (Pinus albicaulis), Sierra lodgepole pine (Pinus contorta spp. murrayana), mountain hemlock (Tsuga mertensiana) and/or California red fir (Abies magnifica).
Classification relationships
Forest Alliance = Abies magnifica-Abies concolor – Red fir - White fir forest; Association = tentatively Abies magnifica-Abies concolor [Sierra Nevada]. (Sawyer, John O., Keeler-Wolf, Todd, and Evens, Julie M. 2009. A Manual of California Vegetation. 2nd ed. California Native Plant Society Press. Sacramento, California.)
Ecological site concept
This site occurs on south-facing mountain slopes (and moraines) at elevations of approximately 7,600 to 9,000 feet. Slopes are typically between 15 and 50 percent. Soils are moderately deep to very deep and derived from volcanic parent material. The vegetation is a productive California red fir (Abies magnifica) – white fir (Abies concolor) forest. California red fir is a slow-growing, long-lived tree that has high frost tolerance and low drought tolerance, and reaches dominance only in cooler and moister upper elevations. White fir has lower frost tolerance and is more drought tolerant, and can co-dominate in this high elevation zone on warmer south-facing aspects. The understory is sparse, with pinemat manzanita (Arctostaphylos nevadensis) is the most common shrub species.
Associated sites
F022AC007CA |
North-Facing Cryic Loamy Mountain Slopes Occurs on adjacent north-facing slopes with moderately deep andic soils. Vegetation is subalpine mixed conifer forest with mountain hemlock (Tsuga mertensiana), red fir (Abies magnifica), western white pine (Pinus monticola), and occassionally lodgepole pine (Pinus contorta var. murrayana). |
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F022AE013CA |
Frigid, Loamy, Volcanic Mountain Slopes Occurs on adjacent mountain slopes with loamy, moderately deep to deep andesitic soils. The vegetation is a white fir (Abies concolor) mixed conifer forest. White fir, jeffrey pine (Pinus jeffreyi), sugar pine (Pinus lambertiana) and incense cedar (Calocedrus decurrens) are all important species. |
F022AX101CA |
Moist Colluvial Headwater System Occurs on adjacent headwater swales and first order streams. A complex of vegetation community types is present, and quaking aspen (Populus tremuloides) is a characteristic species. |
R022AE217CA |
Frigid Volcanic Slopes Occurs on lower elevation slopes with shallow, loamy skeletal soils over stongly cemented andesitic lahar. Vegetation is an open, diverse shrubland with huckleberry oak (Quercus vaccinifolia) and greenleaf manzanita (Arctostaphylos patula) dominant species. |
Similar sites
F022AE008CA |
Frigid Loamy Moraine Slopes This site is found at lower elevations on moraine slopes. Soils are very deep soils, and developed from colluvium over till, from volcanic parent materials. The overstory is similar, but the understory species are more indicative of soil mosisture, with creeping snowberry (Symphoricarpos mollis) an important shrub species. |
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Table 1. Dominant plant species
Tree |
(1) Abies magnifica |
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Shrub |
(1) Arctostaphylos nevadensis |
Herbaceous |
Not specified |
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