Natural Resources
Conservation Service
-
Search
Major Land Resource Area or ecological site by name and/or ID.
General information
Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
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 is highly asymmetrical with a long, 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 certain 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 of Paleozoic and Mesozoic ages. 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 "A" alpine
This LRU occurs at the highest elevations of the Sierra Nevada, above treeline on upper mountain slopes, exposed ridges and mountain peaks. This LRU begins at the alpine treeline ecotone, which occurs at approximately 11,000 feet in the south and central areas and approximately 9,800 feet in the north, and extends up to 14,494 feet (Mount Whitney). Mean annual air temperature (MAAT) ranges from 29 to 35 degrees F, mean annual precipitation (MAP) ranges from 39 to 60 inches, and the frost free season is 20 to 30 days.Ecological site concept
This site occurs on glacially scoured mountain slopes, on moderately deep to very deep soils. The soils have a high percentage of rock fragments (skeletal), and have a deep, dark mineral surface with lots of organic matter (umbric epipedon). This site occurs in swales or concavities on mountain slopes. Slopes are typically greater than 15 percent. Purple mountainheath is dominant, with Parry’s rush (Juncus parryi) common.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Phyllodoce breweri
Herbaceous Not specified