Ecological site group DX035X01DESG04
Henry Mtns-Shallow Shrub & Wood lands-sandy loam
Last updated: 10/12/2022
Accessed: 05/02/2024
Ecological site group description
Key Characteristics
- Henry Mountains
- Shallow Shrublands & Woodlands
- Soils are sandy loams
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 ecological site group is located on dissected pediments, escarpments, ledges, hillslopes on structural benches, benches, rolling ridges, dissected cuestas, structural benches, top mesas, south facing hillslopes, and canyons. Runoff is high to very high. Slopes typically range from 1-20%, but in some areas, slopes are as steep as 60%. Elevations are generally 3700-6000 ft, but this site has been found on elevations as high as 7100 ft.
Climate
The climate is characterized by hot summers and cool to warm winters. Large fluctuations in daily temperatures are common. The mean annual air temperature ranges from 40 to 57 degrees Fahrenheit. Approximately 65–70% of precipitation occurs as rain from March through October. On the average, April, May, and June are the driest months and August, September, and October are the wettest months. Precipitation is extremely variable from month to month and from year to year. Much of the precipitation occurs as convection thunderstorms.
Soil features
The soils are very shallow to shallow and well drained. Typically the dry surface is dark reddish brown to yellowish red. Typically soil surface fragments range from 0-40%. The soil temperature and moisture regimes are mesic and typic aridic respectively. Surface and subsurface textures are generally fine gravelly fine sandy loams, loamy fine sands, gravelly very fine sands, and sandy loams. These soils formed in eolian deposits derived mainly from eroded calcareous sandstone parent materials. Soils are calcareous to the surface and have a layer of carbonate accumulation just above the bedrock. This layer occurs as a hardpan in Limeridge & Deleco soils which are shallow (7-20”) to calcium carbonate cemented hardpan with depth to limestone bedrock of 20 to 40”. Pennell has a horizon with loamier textures (i.e. sandy clay loam) and the available water capacity is 1 to 4 inches, and moderate (0.6 to 2.0 in/hr) permeability. Walknolls Family has 30-80% rock fragments on the surface. Deleco and Walknolls family has 35-70% rock fragments in the control section. Runoff is rapid for slopes over 15%. Lithic Torripsamments (Needle and Suzipon) have somewhat excessive to excessive drainage classes and rapid (greater than 20 in/hr) permeability. Site is often associated with rock outcrops. The average annual soil loss in potential is approximately 0.5-1.5 tons/acre. The soil surface factor (SSF) in potential is 30. Available water holding capacity is 0.6 to 3.1 inches.
Vegetation dynamics
These sites developed under Colorado Plateau ecological conditions and the natural influences of herbivory and climate. Plant species composition is generally dominated by blackbrush with Torrey's jointfir commonly occurring. Some areas will have a sparse layer of Utah juniper and two-needle pinyon. Diverse biological crusts are common on this site, however, site with large amount of surface coarse fragments may lack these crusts. The amount of James galleta and Indian ricegrass present is dependant on weather patterns (summer or winter precipitation)and on soil depth to a restrictive layer. The shallower the soil, the fewer herbaceous species. Blackbrush appears to act as a paleo-endenmic species in this MLRA and may not be able to reestablish itself after significient disturbance.
There is no evidence to indicate that these sites historically maintained a short burn frequency. Large gaps between plants (very discontinuous fuels)in relic areas indicate that this site may have historically rarely burned. Until further research indicates that fire played a significient role in the ecosystem processes of this site, this ecological site group description will not include fire as a disturbance in the reference state. However, due to modern disturbances such as brush treatments and OHV use, the resilience of the historical vegetation may be at risk. Disturbances that result in an opportunity for invasive annuals to enter the system and possibly produce sufficient fuel loads may allow fire to become a risk. Cheatgrass, red brome, and Russian thistle are most likely to invade this site.
These ecological sites have been grazed by domestic livestock since they were first introduced into the area around 1860. It is however highly resistant to grazing due to the unpalatable nature of blackbrush and lack of forage plants. Therefore the introduction of domestic livestock and the use of fencing and reliable water sources have only minimally influenced the historic disturbance regime associated with this ecological site.
Improper livestock grazing including, season long grazing and\or heavy stocking rates, may cause the sites to depart from the reference plant community. As ecological condition deteriorates, perennial grasses and Torrey's jointfir may decrease while yellow cryptantha, locoweed, desert trumpet, blackbrush, and snakeweed may increase. Improper grazing may also increase the chance of invasion by cheatgrass, red brome and invasive annual forbs. On the Colorado Plateau, however, these species are capable of establishing themselves in blackbrush communities in the abscence of grazing, but they rarely increase to where they dominate them.
Major Land Resource Area
MLRA 035X
Colorado Plateau
Subclasses
Correlated Map Unit Components
22592665
Stage
Provisional
Contributors
Victor Parslow, Keith Crossland
Curtis Talbot
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | D = Drought E = Establishment of non-native invasive species ILG = Improper livestock grazing SD = Surface disturbances |
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State 1 submodel, plant communities
1.1a | - | D = Drought ILG = Improper livestock grazing SD = Surface disturbances |
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1.2a | - | PLG = Proper livestock grazing T = Time without disturbances W = Wet weather periods |
State 2 submodel, plant communities
2.1a | - | D = Drought ILG = Improper livestock grazing SD = Surface disturbances |
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2.2a | - | PLG = Proper livestock grazing T = Time without disturbances W = Wet weather periods |