Natural Resources
Conservation Service
Ecological site F022AI202CA
Mesic Lower Montane Cool Drainages
40 - 47 PZ
Accessed: 08/23/2026
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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
MLRA 22A
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 s 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, arĂȘtes, 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 XI Central Sierra Lower Montane
This LRU comprises the lower elevations of the western, central, Sierra Nevada Mountains. Elevations are typically between 2,000 and 4,700 feet, with higher elevations in the south. The frost free season ranges from 150 to 240 days, MAAT ranges from 50 to 62 degrees F, and MAP ranges from 32 to 57 inches. Soil temperature regime is generally mesic, although warmer pockets of thermic exist within this LRU.
Ecological site concept
This site occurs on less droughty parts of the landscape on cooler aspects of 10 - 60% slopes. This ecological site differs from other similar ecological sites by virtue of its less droughty landscape positions of the lower elevations of lower-montane(LRU 22AI). These are more gentle back slope to summit positions, or steeper highly shaded positions. Soil temperature regime is mesic, although post-fire plant community phase may have significantly higher soil temperatures.
Plant communities consist of oak montane mid-canopy dominating the site (canyon live oak/ black oak), toyon, manzanita, poison oak, deer brush and dense ponderosa pine, incense cedar, and scattered sugar pine. Pacific madrone is common in some areas, and dense bearclover usually fills intertree and shrub spaces.Table 1. Dominant plant species
Tree (1) Pinus ponderosa
(2) Quercus kelloggiiShrub (1) Arbutus menziesii
(2) Chamaebatia foliolosaHerbaceous Not specified