Natural Resources
Conservation Service
Ecological site F040XB214AZ
Loamy Bottom, Woodland 7"-10" p.z.
Last updated: 10/17/2024
Accessed: 11/21/2024
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): 040X–Sonoran Basin and Range
Major Land Resource Area (MLRA) 40 is the portion of Sonoran Desert that extends from northwest Mexico into southwestern Arizona and southeastern California. This MLRA is hot desert characterized by bimodal precipitation coupled with hot summers and mild winters. These conditions give rise to a rich biological diversity visually dominated by columnar cactus (saguaro) and leguminous trees (palo verde). This unit occurs within the Basin and Range Physiographic Province and is characterized by numerous mountain ranges that rise abruptly from broad, plain-like valleys and basins. Igneous and metamorphic rock classes dominate the mountain ranges, and basin sediments are combinations of fluvial, lacustrine, colluvial and alluvial deposits.
LRU notes
Land Resource Unit (LRU) 40-2, Middle Sonoran Desert, is characterized as desert scrub vegetation with a moderate percentage of desert pavement on relic fan remnants; trees are common to all sized washes, bottoms and hillslopes. Elevations range from 1200 to 2000 feet and precipitation averages 7 to 10 inches per year. Upland vegetation includes saguaro, palo verde, creosotebush, white bursage, brittlebush, prickly pear, cholla, desert saltbush, wolfberry, and big galleta. The soil temperature regime is hyperthermic and the soil moisture regime is typic aridic.
Classification relationships
USDA-NRCS Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin: Western Range and Irrigated Region D Major Land Resource Area 40 - Sonoran Basin and Range Land Resource Unit 2 - Middle Sonoran Desert Ecological Site Loamy Bottom, Woodland, 7"-10" p.z.
U.S. Environmental Protection Agency, Ecological Regions of North America: Level I, Region 10 North American Deserts Level II, 10.2 Warm Deserts Level III, Ecoregion 81, Sonoran Basin and Range Level IV, 81l, 81n, 81o
USDA-USFS Ecological Subregions: Sections of the Conterminous United States Section 322 American Semidesert and Desert Province Section 322B, Sonoran Desert
Ecological site concept
Loamy Bottom, Woodland, 7"-10" p.z., occurs on stream terraces with a deep water table. Soils do not have visible redoximorphic features. Soil texture ranges from sandy to loamy to silty. The reference plant community is mesquite dominated; understory vegetation is largely absent in areas with dense mesquite canopy cover. Aspect is woodland.
Associated sites
F040XB215AZ |
Sandy Bottom, Woodland 7" - 10" p.z. adjacent stream channels, redox features present in top 80 inches of soil surface |
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Similar sites
R040XA124AZ |
Loamy Bottom, Woodland 10"-13" p.z. Elevations 2,000' - 3,800', higher precipitation, soils are thermic |
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F040XC328AZ |
Loamy Bottom, Woodland 3"-7" p.z. Elevations 300' - 1,200', lower precipitation |
Table 1. Dominant plant species
Tree |
(1) Prosopis velutina |
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Shrub |
(1) Prosopis velutina |
Herbaceous |
Not specified |
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