Ecological site group DX035X01GESG13
Chinle Valley Loamy Washes and Bottoms
Last updated: 10/12/2022
Accessed: 05/02/2024
Ecological site group description
Key Characteristics
- Chinle Valley
- Loamy
- Washes and bottoms
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 group occurs on floodplains along ephemeral streams on floodplains, alluvial fans and low stream terraces. Therefore, it benefits from run-in moisture from adjacent areas. Slopes range from 0 to 5 percent. Elevations range from 5,000 to 6,000 feet.
Climate
Mean annual precipitation varies from 5 to 14 inches with about 60% of it coming as rain from April through October. May and June are the driest months. Most of the precipitation from November through March comes as snow. High-velocity winds are common in late winter and early spring.
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 and -17 degrees F have been recorded. The frost-free period ranges from 140 to 160 days.
The cool-season plants start growth in March and end with plant maturity and seed dissemination about mid-June. Warm-season plants grow from June through September, taking advantage of the moisture and warmth from tropical air out of the Gulf of Mexico. About 40 percent of the total precipitation is received during these summer months. The other 60 percent, received from fall through spring, influences cool-season plants.
Soil features
The soils are deep to very deep and well drained. They are formed in stratified flow deposited alluvium derived from sandstone and shale. Surface textures are frequently loam. The subsoil has textures of silty clay loam, fine sandy loam, silt loam, and very fine sandy loam. Soil moisture is typic aridic or ustic aridic. Permeability is moderately slow. Available water holding capacity is high. Runoff is slow, and the hazard of water erosion is slight. The hazard of soil blowing is severe. The soils are mildly to strongly alkaline (pH 7.4-9.0), nonsaline (EC 0-2), and low sodicity (SAR 5-13).
Vegetation dynamics
This ecological group has a plant community made up primarily of shortgrasses, midgrasses, shrubs, and a relatively small amount of forbs. In the reference plant community there is a mixture of cool-season and warm-season grasses.
Plant species most likely to invade or increase on this site when it deteriorates are black greasewood, annual sunflower, cocklebur, goldenweed, Russian thistle, and threadleaf rubber rabbitbrush. Continuous livestock grazing during winter and spring decreases the cool-season grasses and increases lower forage value grasses and shrubs.
The reference plant community has been determined by study of relict areas or areas protected from excessive grazing. Trends in plant communities going from heavily grazed areas to lightly grazed areas, seasonal use pastures, and historical accounts have also been used.
This group can have a somewhat variable plant community because of the nature and composition of the soils. Frequent deposition of different material types by water and wind processes, and the lack of dependability of available water, will affect the plant community. Areas with frequent flooding will have low-salt tolerant vegetation; however, areas with less-frequent or absent flooding will possibly have a salt-tolerant plant community. Areas that have a stable and pedogenically active soil will have the ability to sustain grasses and native shrubs and trees; areas with recent deposition and little to no pedogenesis will have pioneer species, subject to change from year to year or even season to season.
Major Land Resource Area
MLRA 035X
Colorado Plateau
Subclasses
Correlated Map Unit Components
22397511, 22397400, 22397228, 23000002, 22999498, 22598193, 22598196, 22598335, 22597907, 22598220, 22598389, 22601118
Stage
Provisional
Contributors
Curtis Talbot
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