Natural Resources
Conservation Service
Ecological site R030XD004CA
Low-Production Hyperthermic Hills
Accessed: 11/13/2024
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.
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): 030X–Mojave Basin and Range
MLRA Description:
Major Land Resource Area (MLRA) 30, Mojave Desert, is found in southern California, southern Nevada, the extreme southwest corner of Utah and northwestern Arizona within the Basin and Range Province of the Intermontane Plateaus. The climate of the area is hot (primarily hyperthermic and thermic; however at higher elevations, generally above 5000 feet, mesic, cryic and frigid) and dry (aridic). Elevations range from below sea level to over 12,000 feet in the higher mountain areas found within the MLRA. 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 Description:
This Land Resource Unit (designated by ‘XD’) is found on the eastern side of California. Elevations range from 400 to 2200 feet on average, but may be found up to 3600 feet on southern exposures. Precipitation ranges from 1 to 6 inches per year, but averages between 2-4 inches. This LRU is characterized primarily by the extreme aridity, hot temperatures, hyperthermic soil temperatures and low stature of widely spaced vegetation. Temperatures can reach over 110 degrees Fahrenheit for several weeks in July and August. Summer precipitation falls between July and September, ranging from 20-33% in the form of rain, and winter precipitation falls starting in November and ends between February and March, ranging from 56-70%, also mostly in the form of rain. Vegetation is primarily small, widely-spaced, low-producing creosote bush (Larrea tridentata), burrobush (Ambrosia dumosa), and brittlebush (Encelia farinosa).
Ecological Site Concept –
This ecological site occurs on very dry mountain slopes, hills, and steep sideslopes of fan remnants, at elevations of 570 to 3990 feet. Soils have gravel or channery surface textures, and a high volume of large (greater than 3 inches in diameter) rock fragments by volume in the soil profile.
Vegetation is dominated by very sparse, small creosote bush (Larrea tridentata), and annual forbs contribute 50 to 80 percent of annual production during years of average to above average precipitation. Production Reference Value (RV) is 149 pounds per acre and ranges from 26 to 428 pounds per acre depending on precipitation and annual forb production. A very dry climate, steep slopes and rocky soils with low moisture holding capacity restrict the potential vegetation to this sparse community.
The data in the following sections is from major (15% of mapunit or greater) components only.
Classification relationships
Mojave Creosote Bush (Holland 1986).
Larrea tridentata Shrubland Alliance (Sawyer et al. 2009).
Associated sites
R030XD001CA |
Hyperthermic Dry Hills This ecological site is found on adjacent cooler slopes. Creosote bush (Larrea tridentata) and burrobush (Ambrosia dumosa) are dominant. |
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R030XD003CA |
Hyperthermic Steep South Slopes This ecological site is found on adjacent south-facing slopes. Brittlebush (Encelia farinosa) is dominant. |
R030XD006CA |
Abandoned Fan This ecological site is found on adjacent fan remnants with deep sandy soils. Creosote bush (Larrea tridentata) is dominant. |
R030XD008CA |
Hyperthermic Sandhill This ecological site is found on adjacent sandhills. Big galleta (Pleuraphis rigida) and creosote bush (Larrea tridentata) dominate. |
R030XD014CA |
Hyperthermic Sandy Plains This ecological site is found on adjacent semi-active sandsheets. Big galleta (Pleuraphis rigida) is dominant. |
R030XD025CA |
Hyperthermic Sandsheets This ecological site is found on adjacent sandsheets. Creosote bush (Larrea tridentata) and big galleta (Pleuraphis rigida) dominate. |
R030XD042CA |
Hyperthermic Shallow To Moderately Deep Fan Remnants R030XD042CA is found on adjacent stable fan remnants with a high degree of soil horizon development. Vegetation is sparse and dominated by creosote bush (Larrea tridentata). |
R030XY092NV |
DESERT PATINA This ecological site is found on adjacent stable fan remnants. Surfaces are covered with desert pavement and very sparse vegetation is dominated by creosote bush (Larrea tridentata). |
Similar sites
R030XD006CA |
Abandoned Fan This ecological site is found on fan aprons and fan remnants. |
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R030XD001CA |
Hyperthermic Dry Hills This ecological site is found on similar landforms and soils, but in cooler positions and generally on north-facing slopes. Production and diversity are higher and burrobush (Ambrosia dumosa) is an important species. |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
(1) Larrea tridentata |
Herbaceous |
(1) Chaenactis fremontii |
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