Ecological site group DX035X01AESG02
Grand Staircase-Bottoms & Flats-run in
Last updated: 10/05/2022
Accessed: 05/02/2024
Ecological site group description
Key Characteristics
- Grand Staircase-Kaiparowits
- Bottoms and Flats
- Extra water is from run-in or local water table
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 receives extra run-in water due to its landscape position on flood plains, stream terraces, narrow valleys, and valley flats. Run off is low due to gentle slopes and highly permeable soils. The elevation ranges from 3800 to 6500 ft. This group usually does not have a seasonally high water table, but in some areas spring water table can be within 42 inches of the soil surface.
Climate
The climate is characterized by hot, dry summers and cool winters. Average annual precipitation ranges from 6.5 to 10 inches. Approximately 65% of the total precipitation occurs from July to October, mostly in the form of convection thunderstorms. May and June are typically the driest months during the growing season.
Large fluctuations in daily temperatures are common. Summer temperatures are in the 90's and winter temperatures are in the 20's and 30's.
Soil features
The soils are deep to very deep and well drained to somewhat excessively well drained. Surface and subsurface textures can range from clay loams to sandy loams. There are typically few rock fragments on the soil surface and throughout the profile, but sometimes gravel lenses are present. These soils are usually formed in alluvium derived from sandstone parent materials. The soil temperature regime is mesic and the soil moisture regime is aridic (sometimes ustic aridic). Soils are nonsaline to slightly saline.
Vegetation dynamics
This group is historically dominated by shrubs and a diverse perennial grass understory dominated by Indian ricegrass, James's Galleta, Sporobolus spp, and/or needle-and-thread. The historic fire return interval is presumed to be about 35-100 years (Howard 2003). Fourwing saltbush, Greaswood, Basin Big Sagebrush and native grasses would have resprouted within one year following fire and maintained dominance of the site. There is no evidence that prolonged drought would dramatically alter the species composition of the site in reference condition, although production is expected to be lower. Inundation, persistent heavy browsing, and/or insect herbivory would have resulted in reduced fourwing saltbush and a grass-dominated plant community.
Today this group often burns less frequently due to fire suppression efforts and reduced fine fuel loads resulting from livestock grazing. In addition, excessive livestock grazing during the spring and summer can cause native grasses and forbs to lose vigor or disappear from the community completely.
Invasive plant species, particularly cheatgrass, Russian thistle, and annual mustards, can establish on the site given a seed source and germination sites in disturbed soil. These invasive annuals require little or no disturbance to establish, although disturbances often provide germination sites and/or seed sources that accelerate invasion.
When the ecological processes are altered due to improper grazing, prolonged drought, altered fire regime, invasive species dominance, and/or other disturbances, alternative states can occur that differ from the historic reference state in both plant community structure and ecological function.
Major Land Resource Area
MLRA 035X
Colorado Plateau
Subclasses
Correlated Map Unit Components
22601699, 22601854, 22601373, 22601749, 22601256, 22601879, 22965132, 22965610, 22965430, 22965677, 22965554, 22965276, 22965275, 22965272, 22965553, 22965282, 22965280, 22965686, 22965685, 22965689, 22965174, 22963395, 22963397
Stage
Provisional
Contributors
Curtis Talbot
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