Ecological site group DX035X01CESG03
Mesas and Benches - Outcrops and Slopes
Last updated: 10/05/2022
Accessed: 05/02/2024
Ecological site group description
Key Characteristics
- Mesa and Benches
- Outcrops and Slopes
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.
Physiography
This site occurs on escarpments and hillslopes associated with structural benches, ledges on escarpments, dissected structural benches, side slope canyons, canyon walls, and scarp slopes on cuestas. Run off is very high. Slopes typically range from 15-80%, and elevations are generally 4800-6900ft.
Climate
The climate is characterized by hot summers and cool to warm winters. Large fluctuations in daily temperatures are common. Mean annual high temperatures range from 60-70 degrees Fahrenheit and mean annual low temperatures range from 32-40 degrees Fahrenheit. Approximately 70-75% occurs as rain from March through October. On the average, February, May, and June are the driest months and July through October are the wettest months. Precipitation is extremely variable from month to month and from year to year but averages between 9-12 inches. Much of the summer precipitation occurs as convection thunderstorms.
Soil features
The soils are very shallow (rarely moderately deep) and are well drained. Typically, the dry surface color ranges from dark brown to yellowish red. The soil temperature and moisture regimes are mesic and ustic aridic respectively. Surface textures are generally sandy loams but can range to very fine sandy loams, silt loams, loams, and fine sandy loams. Subsurface textures are generally loamy sands, cobbly loams, channery loams, or gravelly sandy loams. Soils are nonsaline to slightly saline.
Vegetation dynamics
This group developed under Colorado Plateau ecological conditions, and the natural influences of herbivory and climate. Species composition is generally dominated by a sparse layer of Utah juniper and two-needle pinyon. Bigelow sagebrush, mormon tea and blackbrush are common shrub species. Perennial herbaceous species occurrence is highly variable with Indian ricegrass, Salina wildrye and desert needlegrass found most often. There is no evidence to indicate that this group historically maintained a short burn cycle.
Drought and insect damage appear to be the main driving factors in many pinyon/juniper communities. Betancourt et al. (1993), noted that pinyon and juniper woodlands in the southwest appear to be more susceptible to large die-offs during droughts, than at other locations. If a severe drought persists, two-needle pinyon being more susceptible to drought and insect damage than Utah juniper, appear to die out first, while the Utah juniper may survive. This event could allow for an increase in shrubs and herbaceous species during periods when wetter years return.
Major Land Resource Area
MLRA 035X
Colorado Plateau
Correlated Map Unit Components
22857819, 22933935, 22934192, 22934083, 22933987, 22933989, 22934259, 22934015, 22934014
Stage
Provisional
Contributors
Vic Parslow
Keith Crossland
Curtis Talbot
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Ecosystem states
T1A | - | ILG = Improper Livestock Grazing D = Drought SD = Surface Disturbance IW = Invasive Weed Source |
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State 1 submodel, plant communities
1.1a | - | ILG = Improper Livestock Grazing D = Drought SD = Surface Disturbance |
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1.2a | - | PLG = Proper Livestock Grazing W = Wet Weather Periods T = Time |
State 2 submodel, plant communities
2.1a | - | ILG = Improper Livestock Grazing D = Drought SD = Surface Disturbance |
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2.2a | - | PLG = Proper Livestock Grazing W = Wet Weather Periods T = Time |