Natural Resources
Conservation Service
Ecological site F022AF002CA
Frigid, Sandy, Or Loamy Outwash
Accessed: 12/30/2024
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.
LRU "F" Northeast Mixed Conifer: This LRU includes the drier eastside forests of the northern Sierra Nevada that occur north of Bridgeport, the eastern, lower elevations of the Tahoe area, and the northern extent of the Sierra near Susanville, most closely corresponding to EPA ecoregion 5f. Elevations are typically between 5,000 and 8,000 feet. The frost free season is between 50 and 100 days, MAAT is between 40 and 48 degrees F, and MAP is typically between 17 and 35 inches, but may range higher in the northernmost section. This LRU exists in the rain shadow formed by the Sierra Nevada Crest, and consequently has much lower precipitation than equivalent elevations on western slopes. Soil temperature regimes are mostly frigid, with some cryic. Soil moisture regimes are xeric.
Classification relationships
Smith, Sydney. 1994. Ecological Guide to Eastside Pine Associations. USDA Forest Service, Pacific Southwest Region. R5-ECOL-TP-004. PIPO-ABCO/PUTR-ARPA-STOC1
Forest Alliance = Pinus jeffreyi – Jeffrey pine forest; Association = tentatively Pinus jeffreyi/Arctostaphylos patula. (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 ecological site is found on gently sloping outwash, primarily on the eastern side of Lake Tahoe where precipitation is relatively low. Elevations range from 6,200 to 7,500 feet. Slopes are typically between 0 and 15 percent. Soils are very deep, and are derived from predominately granitic parent material. This exposed, dry environment with coarse soils that have low water holding capacity supports an open canopy Jeffrey pine (Pinus jeffreyi) forest with an open understory of low shrub cover. Greenleaf manzanita (Arctostaphylos patula), prostrate ceanothus (Ceanothus prostratus) and whitethorn ceanothus (Ceanothus cordulatus) are the most common shrubs. Coarse soils and low precipitation does not support an extensive herbaceous understory, and forbs and grasses are relatively sparse on this site.
Associated sites
F022AE007CA |
Frigid, Sandy, Moraines And Hill Slopes Occurs on adjacent moraines and hillslopes with greater precipitation and sandy, moderately deep to very deep soils. The vegetation is white fir (Abies concolor) - Jeffrey pine (Pinus jeffreyi) forest. |
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F022AE013CA |
Frigid, Loamy, Volcanic Mountain Slopes Occurs on adjacent mountain slopes with moderately deep to deep soils derived from andesite. The vegetation is a white fir (Abies concolor) - mixed conifer forest. Jeffrey pine (Pinus jeffreyi), sugar pine (Pinus lambertiana) and incense cedar (Calocedrus decurrens) are all important species. |
F022AE025CA |
Loamy Moist Outwash This site occurs on adjacent valley bottoms on outwash and on old river and lake terraces with very deep, gently sloping soils formed in alluvium. The vegetation is a mixed conifer forest of white fir (Abies concolor), Jeffery pine (Pinus jeffreyi) and sugar pine (Pinus lambertiana). The understory is diverse, and Utah serviceberry (Amelanchier utahensis) and thimbleberry (Rubus parviflorus) are common shrub species. |
F022AF003CA |
Frigid, Loamy, Fragipan, Outwash Occurs on adjacent very deep soils from outwash and alluvium from mixed sources. Soils have a weak fragipan at 12 to 65 inches. The vegetation is dense Sierra lodgepole pine (Pinus contorta var. murrayana) forest with sparse grasses in the understory. |
F022AF005CA |
Frigid, Deep To Very Deep, Sandy-Loamy Mountain Slopes Occurs on adjacent north-facing mountain slopes. Jeffrey pine (Pinus jeffreyi) and white fir (Abies concolor) co-dominate. |
F022AX100CA |
Frigid, Sandy, Moist, Outwash Fan This site occurs on gently sloping outwash with very deep, poorly drained soils formed in alluvium from glacial outwash fans. The vegetation is a Sierra lodgepole pine (Pinus contorta var. murrayana) forest with a productive understory of willows and forbs. |
R022AX105CA |
Steep Mountain Drainageways Occurs on steep mountain drainageways with very deep, frigid, sandy, aquic, alluvial soils, along Rosgen B or A type channels. A complex of community types is present. Aspen (Populus tremuloides), Lemmon's willow (Salix lemmonii) and thinleaf alder (Alnus incana spp. tenuifolia) are characteristic species. |
Similar sites
F022AE025CA |
Loamy Moist Outwash This site occurs in the "AE" LRU, which receives greater precipitation. White fir (Abies concolor) co-dominates with Jeffrey pine (Pinus jeffreyi) and the understory reflects increased soil moisture, with thimbleberry (Rubus parviflorus) and creeping snowberry (Symphoricarpos mollis) dominant species. |
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F022AF004CA |
Frigid, Shallow To Deep, Sandy Mountain Slopes This site occurs on south-facing mountain slopes. This is an open forest dominated by low cover of Jeffrey pine (Pinus jeffreyi). Antelope bitterbrush (Purshia tridentata) is a dominant shrub in the understory with greenleaf manzanita (Arctostaphylos manzanita). |
F022AE007CA |
Frigid, Sandy, Moraines And Hill Slopes This site occurs in the "AE" LRU, which receives more precipitation, allowing white fir (Abies concolor) to co-dominate with Jeffrey pine (Pinus jeffreyi). |
F022AF005CA |
Frigid, Deep To Very Deep, Sandy-Loamy Mountain Slopes This site occurs on mountain slopes. The forest is composition is similar, but this site has greater potential for white fir (Abies concolor) and incense cedar (Calocedrus decurrens). |
F022AF006CA |
Loamy Frigid Metamorphic Slopes This site occurs on mountain slopes developed from metamorphic soils. White fir (Abies concolor) co-dominates with Jeffrey pine (Pinus jeffreyi), and the understory composition reflects greater soil moisture holding capacity, with creeping snowberry (Symphoricarpos mollis) and wax currant (Ribes cereum)dominant species. |
Table 1. Dominant plant species
Tree |
(1) Pinus jeffreyi |
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Shrub |
(1) Arctostaphylos patula |
Herbaceous |
(1) Pedicularis semibarbata |
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