
Natural Resources
Conservation Service
Ecological site R028AY006NV
DROUGHTY LOAM 5-8 P.Z.
Last updated: 6/12/2025
Accessed: 10/22/2025
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): 028A–Ancient Lake Bonneville
MLRA 28A occurs in Utah (82%), Nevada (16%), and Idaho (2%). It makes up about 36,775 square miles. A large area west and southwest of Great Salt Lake is a salty playa. This area is the farthest eastern extent of the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. It is an area of nearly level basins between widely separated mountain ranges trending north to south. The basins are bordered by long, gently sloping alluvial fans. The mountains are uplifted fault blocks with steep side slopes. They are not well dissected because of low rainfall in the MLRA. Most of the valleys are closed basins containing sinks or playa lakes. Elevation ranges from 3,950 to 6,560 ft. in the basins and from 6,560 to 11,150 ft. in the mountains. Most of this area has alluvial valley fill and playa lakebed deposits at the surface. Great Salt Lake is all that remains of glacial Lake Bonneville. A level line on some mountain slopes indicates the former extent of this glacial lake. Most of the mountains in the interior of this area consist of tilted blocks of marine sediments from Cambrian to Mississippian age. Scattered outcrops of Tertiary continental sediments and volcanic rocks are throughout the area. The average annual precipitation is 5 to 12 ins. in the valleys and is as much as 49 ins. in the mountains. Most of the rainfall occurs as high-intensity, convective thunderstorms during the growing season. The driest period is from midsummer to early autumn. Precipitation in winter typically occurs as snow. The average annual temperature is 39 to 53 °F. The freeze-free period averages 165 days and ranges from 110 to 215 days, decreasing in length with elevation. The dominant soil orders in this MLRA are Aridisols, Entisols, and Mollisols. The soils in the area dominantly have a mesic or frigid soil temperature regime, an aridic or xeric soil moisture regime, and mixed mineralogy. They generally are well drained, loamy or loamy-skeletal, and very deep.
Ecological site concept
This site occurs on offshore bars, fan skirts and beach plains of all exposures. Slopes range from 2 to 30 percent but slope gradients of 4 to 15 percent are typical. Elevations are 4500 to 5500 feet.
The climate associated with this site is semiarid, characterized by cool, moist winters and warm, dry summers. Average annual precipitation is 5 to 8 inches. Mean annual air temperature is 47 degrees F. The average growing season is about 100 to 130 days.
The soils associated with this site are very deep, somewhat excessively drained, have medium runoff and have moderate permeability. They are moderately to strongly alkaline and calcareous throughout. Soil pH ranges from 7.9 to 9.0. The soil surface is covered with about 50 percent pebbles. The soil profile consists of extremely gravelly loamy fine sands and extremely gravelly coarse sands. Rock fragments and coarse fragments in the profile occupy plant growing space and reduce the potential soil moisture holding capacity.
The reference state is dominated by spiny hopsage, fourwing saltbush and Indian ricegrass. Production ranges from 300 to 700 pounds per acre.
Associated sites
R028AY012NV |
LOAMY 5-8 P.Z. |
---|---|
R028AY018NV |
COARSE GRAVELLY LOAM 5-8 P.Z. |
Similar sites
R028BY052NV |
DROUGHTY LOAM 8-10 P.Z. ARTRW-GRSP codominant shrubs |
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R028BY078NV |
DROUGHTY LOAM 5-8 P.Z. PLJA rare to absent |
R028AY028NV |
DROUGHTY LOAM 8-10 P.Z. ARTRW codominant shrub, with GRSP |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
(1) Grayia spinosa |
Herbaceous |
(1) Achnatherum hymenoides |
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