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Natural Resources
Conservation Service
Ecological site F026XY067NV
Steep Bouldery Loam 15-17 P.Z. PIFL2/ARTRV/LEKI2-KOMA
Last updated: 4/10/2024
Accessed: 08/16/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 026X–Carson Basin and Mountains
MLRA 26 is in western Nevada and eastern California; approximately 69 percent is in Nevada, and 31 percent in California. The area is predominantly in the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. Isolated north- south trending mountain ranges are separated by aggraded desert plains. The mountains are uplifted fault-blocks with steep side slopes. The valleys are drained by three major rivers flowing east across MLRA 26; the Truckee, Carson and Walker rivers. A narrow strip along the western border of MLRA 26 is in the Sierra Nevada Section of the Cascade-Sierra Mountains Province of the Pacific Mountain System. The Sierra Nevada Mountains are primarily a large fault-block that has been uplifted with a dominant tilt to the west. The structure creates an impressive wall of mountains directly west of the area creating a rain shadow affect to MLRA 26. Parts of the eastern face; the foothills, mark the western boundary of the area. Elevations range from near 3,806 feet (1,160 meters) on the west shore of Pyramid Lake to 11,653 feet (3,552 meters) on the summit of Mount Patterson in the Sweetwater Mountains.
In MLRA 26, the valleys are composed dominantly of Quaternary alluvial deposits. Quaternary playa or alluvial flat deposits typically occupy the lowest valley bottoms in the internally drained valleys. Tertiary andesitic flows, breccias, ash flow tuffs, rhyolite tuffs or granodioritic rocks dominate the hills and mountains. Quaternary basalt flows are present in lesser amounts. Jurassic and Triassic limestone and shale, and Precambrian limestone and dolomite are also present in very limited amounts. Glacial till deposits, of limited extent are along the east flank of the Sierra Nevada Mountains; the result of alpine glaciation.
The average annual precipitation in MLRA 26 is 5 to 36 inches (125 to 915 millimeters), increasing with elevation. Most of the rainfall occurs as high-intensity, convective storms in spring and autumn. Precipitation is mostly snow in winter. Summers are dry. The average annual temperature is 37 to 54 degrees F (3 to 12 degrees C). The freeze-free period averages 115 days and ranges from 40 to 195 days, decreasing in length with elevation.
The dominant soil orders in MLRA 26 are Aridisols and Mollisols. The soils in the area typically have a mesic soil temperature regime, an aridic or xeric soil moisture regime, and mixed or smectitic mineralogy. The soils are generally well drained, clayey or loamy and are commonly skeletal. The soils depths are typically very shallow to moderately deep.
This area supports shrub-grass vegetation characterized by big sagebrush. Low sagebrush and Lahontan sagebrush are on some soils. Antelope bitterbrush, squirreltail, desert needlegrass, Thurber needlegrass, and Indian ricegrass are important associated plants. Green ephedra, Sandberg bluegrass, desert peach, and several forb species are also common. Juniper-pinyon woodland is typical on mountain slopes. Jeffrey pine, lodgepole pine, white fir, and manzanita grow on the highest mountain slopes. Shadscale is the typical plant in the drier parts of the area. Sedges, rushes, and moisture-loving grasses grow on the wettest parts of the wet flood plains and terraces. Basin wildrye, alkali sacaton, saltgrass, buffaloberry, black greasewood, and rubber rabbitbrush grow on the drier sites that have a high concentration of salts.
Wildlife species in the area are mule deer, coyote, beaver, muskrat, jackrabbit, cottontail, raptors, pheasant, chukar, blue grouse, mountain quail, and mourning dove, amongst other species. The species of fish in the area include trout and catfish. The Lahontan cutthroat trout in the Truckee River is a threatened and endangered species.
LRU notes
The Sierra Influenced Ranges LRU is characterized by wooded great basin mountains and climatic and biotic affinities to the Sierra Nevada Mountain range. The Sierra Influenced Ranges LRU receives greater precipitation than the mountain ranges of central Nevada.
Amount of precipitation varies in relation to the local strength of the Sierra Nevada rain shadow, characterized by pinyon and juniper trees. The White, Sweetwater, Pine Nut, Wassuk, and Virginia ranges of Nevada support varying amounts of Sierra Nevada flora, like ponderosa pine.
Elevations range from 1610 to 2420 meters and slopes range from 5 to 49 percent, with a median value of 22 percent.
Frost free days (FFD) ranges from 92 to 163.
Ecological site concept
This forestland community is on smooth to concave mountain side slopes. The site is found on northerly aspects at lower elevations and on all aspects at higher elevations. Slopes range from 8 to over 75 percent but are typically 50 to 75 percent. Elevations are about 9,000 feet to over 10,000 feet (2743 to 3048 meters). The soil typically has 35 to 50 percent gravels, cobbles, or stones, by volume, distributed throughout the soil profile. The surface soil texture is very bouldery sandy loam. The dominant plants are limber pine (Pinus flexilis), mountain big sagebrush (Artemisia tridentata ssp. vaseyana), spike fescue (Leucopoa kingii), prairie Junegrass (Koeleria macrantha).
Associated sites
R026XY028NV |
MOUNTAIN RIDGE Found on adjacent ridges. |
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Table 1. Dominant plant species
Tree |
(1) Pinus flexilis |
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Shrub |
(1) Artemisia tridentata ssp. vaseyana |
Herbaceous |
(1) Leucopoa kingii |
Click on box and path labels to scroll to the respective text.
Ecosystem states
T | - | This transition is a result of disturbance for example, overgrazing. |
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State 1 submodel, plant communities
1.1a | - | This pathway is a result of a high severity, stand replacing fire which would reduce tree cover and allow for the herbaceous understory to increase. |
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1.1b | - | This pathway is a result of time without disturbance such as fire, drought or disease which will allow for the trees and shrubs to increase in height and density. |
1.2a | - | This pathway is a result of time without disturbance such as fire, drought or disease which will allow for the trees and shrubs to increase in height and density. |
1.3a | - | This pathway is a result of time without disturbance such as fire, drought or disease which will allow for the trees and shrubs to increase in height and density. |
1.3b | - | This pathway is when fire reduces the maturing trees and shrubs and herbaceous understory cover increases. |
1.4a | - | This pathway is when fire reduces the maturing trees and shrubs and the herbaceous understory cover increases. |
State 2 submodel, plant communities
2.1a | - | This pathway is a result of high severity, stand replacing, fire which reduces tree cover and increases herbaceous understory cover. |
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2.1b | - | This pathway is a result of time without disturbance such as fire, drought or disease where the trees and shrubs increase in height and density. |
2.2a | - | This pathway is a result of time without disturbance such as fire, drought or disease where the trees and shrubs increase in height and density. |
2.3b | - | This pathway is a result of high severity, stand replacing, fire reducing tree cover and increasing herbaceous understory. |