Ecological site group DX035X01GESG02
Chinle Valley Sodic Uplands Stream Terraces
Last updated: 10/12/2022
Accessed: 05/02/2024
Ecological site group description
Key Characteristics
- Chinle Valley
- Sodic
- Uplands
- Stream terraces
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 fan remnants, low stream terraces, and swales of valley floors below mesas and cuestas. Elevations range from 3800 to 6100 feet.
Climate
The 35.2 Colorado Plateau Cold Desert Shrub - Grassland common resource area has a very dry and windy climate that is hot in the summer and cold in the winter. The annual precipitation averages between 6 and 14 inches. The soil moisture regime is typic aridic or ustic aridic and the soil temperature regime is mesic. 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 (average range of 1 to 17 inches) falls from December through February, but rarely lasts more than a few days. A seasonal drought occurs from late May through early July. Summer rains occur from July through September during brief intense local thunderstorms. The rain is sporadic in intensity and location. The moisture originates from the Gulf of Mexico in the early summer and the Gulf of California in the late summer/early fall. May and June are the driest months.
Mean temperatures for the hottest month, July, are about 83 degrees F. The coldest month is January, when the mean temperature is about 27 degrees F. Extreme temperatures of 104 degrees F and –17 degrees F have been recorded. Frost-free period ranges from 140 to 160 days.Windy conditions are common year round, but the winds are strongest and most frequent during the spring.
Soil features
Soils on this site are very deep and well-drained. They are formed from alluvium derived from sandstone, shale, and siltstone. The soil is slightly to strongly effervescent in the surface and subsurface profile. Soils are slightly sodic (SAR 5-13), slightly saline (EC 2-16), moderately to very strongly alkaline (pH 7.9-9.6) and are affected by soluble salts.
Vegetation dynamics
Natural disturbances, such as drought, fire, grazing of native fauna, and insects, are inherent in the development and maintenance of these plant communities. The effects of these disturbances are part of the range of characteristics of the ecological site. Fluctuations in plant community structure and function caused by the effects of natural disturbances help establish the boundaries and characteristics of an ecological site. They are accounted for as part of the range of characteristics of the ecological site. Recognizable plant community phases are identified in the reference state of the ecological site. Some sites may have a small range of variation, while others have a large range. Some plant community phases may exist for long periods of time, while others may only occur for a couple of years after a disturbance.
Plant species most likely to invade or increase on this site when it deteriorates are black greasewood, Russian thistle, Powell's saltweed, Torrey seepweed (Mojave seablite), annual grama, Russian thistle, and other annual forbs.
Continuous livestock grazing during winter and spring decreases the cool-season grasses and increases lower forage value grasses and shrubs.
Major Land Resource Area
MLRA 035X
Colorado Plateau
Subclasses
Correlated Map Unit Components
22999409, 23000050, 22999494
Stage
Provisional
Contributors
Curtis Talbot
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