Ecological site group DX035X01GESG19
Chinle Valley Shale or Clayey Shallow
Last updated: 10/12/2022
Accessed: 05/02/2024
Ecological site group description
Key Characteristics
- Chinle Valley
- Shale or clayey
- Upland
- Moderately deep to very deep
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 footslopes, backslopes and canyon sides over shale bedrock, gently sloping plains, plateaus or fan remnants. Also occurs on summits and footslopes of mesas and buttes, hills and escarpments, and pediments. Slopes generally range from 0 to 60 percent. Elevations are generally 3500 to 6000 ft.
This group occurs in an upland position. It neither benefits from run-in moisture nor sustains excessive runoff unless denuded of its vegetation.
Climate
Area has a very dry and windy climate that is hot in the summer and cold in the winter. Average annual precipitation is from 6 to 10 inches. A slight majority of the precipitation arrives during the late fall, winter, and early spring. this winter season moisture originates in the Pacific Ocean and arrives as rain, or sometimes snow, during widespread frontal storms of generally low intensity. The majority of the snow falls from December through February, but rarely lasts more than a few days. The driest period is from late May to early July. Summer rains occur from July through September during brief intense local thunderstorms. The rain is sporadic in intensity and location.
Summer daytime temperatures are commonly 95 - 100 F and on occasion exceed 105 F. Winter air temperatures can regularly go below 10 F and have been recorded below - 20 F. Mean annual air temperature ranges from 46 to 52 degrees fahrenheit. Large fluctuations in daily temperatures are typical.
Windy conditions are common year round with the strongest most frequently in the spring.
Soil features
Soils in this group are shallow and well drained to shale parent material. The surface layer is clay, silty clay, or clay loam. The substratum is clay or silty clay. Permeability is very slow. Available water capacity is moderate. Salinity is low to high. The water erosion hazard is moderate to severe and the wind erosion hazard is slight. Effective rooting depth is typically shallow into the fractured parent material. Soils are moderately alkaline (pH 7.4-8.4). Soil moisture regime is typic aridic or ustic aridic, and the soil temperature regime is mesic.
Vegetation dynamics
Large gaps between plants in relic areas indicate that this site did not historically burn often enough for fire to strongly influence the ecological processes of this site. Until further research indicates otherwise, this ecological site description will not include fire as a disturbance in the reference state. Other disturbances such as brush treatments, invasive species, and OHV use, could reduce the resilience of the reference community, creating risk.
This group provides only marginal livestock grazing due to the small amount forage available and the shortage of drinking water. However, the plants present are easily accessible and relatively nutritious. Improper grazing practices can cause any grasses, and perennial forbs present to be grazed out. Improper grazing coupled with drought can also remove the mat saltbush and other shrubs. Once the native community is lost on these soils it is very difficult to get desirable vegetation back.
Halogeton and Russian thistle are most likely to invade this site. At this time, cheatgrass is not readily invading these sites likely due the chemical properties of the soil. Drought, erosion or improper grazing, in combination, can permanently alter the reference plant community.
Other natural disturbance mechanisms include fluctuations in climate, which influence the soil/water/vegetation relationships. These fluctuations can facilitate changes in production from one year to the next.
Major Land Resource Area
MLRA 035X
Colorado Plateau
Subclasses
Correlated Map Unit Components
22397312, 22397198, 22397252, 22960380, 22857869, 22934066, 22933937, 22933800, 22999412, 22999443, 22999484, 22999633, 22999653, 22999791, 23000031, 22999807, 22999843, 22601660
Stage
Provisional
Contributors
Curtis Talbot
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