Natural Resources
Conservation Service
Ecological site R030XD042CA
Hyperthermic Shallow To Moderately Deep Fan Remnants
Last updated: 10/21/2024
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 notes
This LRU (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).
Classification relationships
This ecological site is found within the Larrea tridentata Shrubland Alliance (Sawyer et al. 2009).
Ecological site concept
This ecological site occurs on stable, undulating fan remnants and fan aprons over fan remnants at elevations of 525 to 2560 feet. Dominant soils have a high degree of horizon development, and typically have a root and water limiting silica and/or calcium carbonate- cemented duripan at shallow to moderately deep depths.
Vegetation is very sparse, and is typically patchy, restricted to breaks in the remnant surface. Shrub density is less than 100 individuals per acre. Production reference value (RV) is 45 pounds per acre, and depending on precipitation annual forb production, ranges from 20 to 85 pounds per acre. The site is dominated by creosote bush (Larrea tridentata), with burrobush (Ambrosia dumosa) and white ratany (Krameria grayi) are sparsely present. Root limiting soil horizons coupled with hyperthermic soil temperatures and low precipitation limits production and shrub density.
The data in the following sections is from major (15% of map unit or greater) components only.
This site is part of group concept R030XD006CA.
Associated sites
R030XD003CA |
Hyperthermic Steep South Slopes R030XD003CA is found on adjacent hillslopes. Brittlebush (Encelia farinosa) is dominant. |
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R030XD004CA |
Low-Production Hyperthermic Hills R030XD004CA is found on adjacent hillslopes and steep sideslopes of fan remnants. Sparse vegetation is dominated by creosote bush (Larrea tridentata). |
R030XD006CA |
Abandoned Fan R030XD006CA occurs on adjacent fan aprons. Creosote bush (Larrea tridentata) is dominant. |
R030XD008CA |
Hyperthermic Sandhill R030XD008CA occurs on adjacent dunes. Big galleta (Pleuraphis rigida) is dominant, and creosote bush (Larrea tridentata) is a common secondary shrub. |
R030XD015CA |
Hyper-Arid Fans R030XD015CA is found on adjacent rarely flooded fan aprons. Creosote bush (Larrea tridentata) and burrobush (Ambrosia dumosa) are co-dominant. |
R030XY023CA |
Hyperthermic Dissected Shallow Pediment R030XD023CA is found on adjacent pediments. Mojave indigobush (Psorothamnus arborescens) and desertsenna (Senna armata) are dominant. |
R030XD025CA |
Hyperthermic Sandsheets R030XD025CA occurs on adjacent sandsheets. Creosote bush (Larrea tridentata) is dominant and big galleta (Pleuraphis rigida), burrobush (Ambrosia dumosa) and dyebush (Psorothamnus emoryi) are secondary species. |
R030XD041CA |
Channeled Warm Alluvial Fans R030XD041CA is found on adjacent rarely flooded, channeled fan remnants. Creosote bush (Larrea tridentata), brittlebush (Encelia farinosa) and burrobush (Ambrosia dumosa) are dominant. |
R030XY001CA |
Occasionally Flooded, Hyperthermic, Diffuse Ephemeral Stream R030XY001CA is found on adjacent occasionally flooded, small ephemeral drainageways. Creosote bush (Larrea tridentata) and Schott's dalea (Psorothamnus schottii) are dominant. |
Similar sites
R030XD015CA |
Hyper-Arid Fans R030XD015CA occurs on rarely flooded fan aprons and fan remnants,typically with deeper soils. Production and shrub density are much higher, and the site is co-dominated by creosote bush (Larrea tridentata) and burrobush (Ambrosia dumosa). |
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R030XD006CA |
Abandoned Fan R030XD006CA occurs on fan aprons and fan remnants with typically deeper soils. Production and shrub density is higher. |
Table 1. Dominant plant species
Tree |
Not specified |
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Shrub |
(1) Larrea tridentata |
Herbaceous |
(1) Cryptantha |
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