Natural Resources
Conservation Service
Ecological site R034AY331CO
Sandy Slopes
Last updated: 9/07/2023
Accessed: 11/23/2024
General information
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.
MLRA notes
Major Land Resource Area (MLRA): 034A–Cool Central Desertic Basins and Plateaus
Major Land Resource Area (MLRA): 34A-Cool Central Desertic
Basins and Plateaus
For further information regarding MLRAs, refer to:
http://soils.usda.gov/survey/geography/mlra/index.html
LRU notes
Land Resource Unit (LRU) 34A-10:
• Moisture Regime: aridic ustic
• Temperature Regime: frigid
• Dominant Cover: rangeland
• Representative Value (RV) Effective Precipitation: 11-12 inches (10 to 14 inches)
• RV Frost-Free Days: 75-95 days
Classification relationships
Relationship to Other Established Classification Systems
Ecoregions (EPA):
Level I: 10 North American Deserts
Level II: 10.1 Cold Deserts
Level III: 10.1.4 Wyoming Basin
Ecological site concept
• This site does not receive any additional water.
• These soils:
o are not saline or saline-sodic
o are very deep
o are not skeletal within 20” of the soil surface; and have minimal rock fragments at the soil surface
o are not strongly or violently effervescent in the surface mineral layer (within top 10”)
o have surface textures that usually range from loamy fine sand to fine sandy loam in surface mineral layer (4”)
• have slopes less than 30 percent
• does not have a clay content that is greater than 35% in mineral soil surface layer (1-2”)
Associated sites
| R034AY330CO |
Sandy Land |
|---|
Similar sites
| R034AY293CO |
Sandhills |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Artemisia tridentata ssp. wyomingensis |
| Herbaceous |
(1) Hesperostipa comata |
Physiographic features
The topography of this site is rolling to fairly steep hillsides.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Alluvial fan |
|---|---|
| Runoff class | Very low to medium |
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 1,829 – 2,195 m |
| Slope | 10 – 30% |
| Aspect | Aspect is not a significant factor |
Climatic features
Mean annual precipitation is 11 to 12 inches, ranging from 10 to 14 inches.
This site has a hard freeze free periods of 135 to 180 days (24ºF).
Mean annual air temperature is between 42 and 45 degrees Fahrenheit.
Mean annual soil temperature is between 43 and 46 degrees Fahrenheit.
Table 3. Representative climatic features
| Frost-free period (characteristic range) | 75-95 days |
|---|---|
| Freeze-free period (characteristic range) | 135-180 days |
| Precipitation total (characteristic range) | 254-356 mm |
| Frost-free period (actual range) | 75-95 days |
| Freeze-free period (actual range) | |
| Precipitation total (actual range) | 254-356 mm |
| Frost-free period (average) | 80 days |
| Freeze-free period (average) | 155 days |
| Precipitation total (average) | 305 mm |
Figure 1. Monthly precipitation range
Figure 2. Monthly average minimum and maximum temperature
Influencing water features
None
Wetland description
None
Soil features
Soils are very deep and excessively drained. The surface soil is loamy fine sand two inches thick and light yellow brown. The texture of the subsoil is fine sandy loam to a depth of 28 inches and is light brownish gray. The underlying material is fine sandy loam to a depth of more than 60 inches and is pale yellow. The water holding capacity is moderate and runoff is medium. The soil is calcareous throughout. Hazard of water erosion and wind erosion is high.
Soils correlated to this site are:
Grieves loamy fine sand 10 to 30 percent slope
Table 4. Representative soil features
| Parent material |
(1)
Alluvium
–
sandstone
(2) Residuum – sandstone |
|---|---|
| Surface texture |
(1) Loamy fine sand |
| Family particle size |
(1) Sandy |
| Drainage class | Well drained to excessively drained |
| Permeability class | Rapid to very rapid |
| Soil depth | 152 cm |
| Surface fragment cover <=3" | 0 – 5% |
| Available water capacity (0-101.6cm) |
7.37 – 14.73 cm |
| Calcium carbonate equivalent (0-101.6cm) |
0 – 5% |
| Soil reaction (1:1 water) (0-101.6cm) |
6.6 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
0 – 15% |
Ecological dynamics
When this site is near its potential, a combination of grasses, forbs and shrubs will be present. The dominant grasses include Indian ricegrass, needle and thread, western wheatgrass, galleta, bottlebrush squirreltail, and prairie Junegrass. The most abundant shrubs include antelope bitterbrush, and Wyoming big sagebrush.
This site is very fragile with highly erosive soils. If degradation is cattle induced, the more palatable plants such as needle and thread, bluebunch wheatgrass, Indian ricegrass, and antelope bitterbrush will decrease in relative production. If degradation is sheep induced, the more palatable plants such as Wyoming big sagebrush, antelope bitterbrush, bluebunch wheatgrass, Indian ricegrass, needleleaf sedge, and threadleaf sedge will decrease in relative production. Utah juniper and pinyon pine will invade the site along with cheatgrass and annual mustards. As the site continues to degrade, the trees will become dominant and the soil becomes susceptible to extreme soil erosion.
State and transition model
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Ecosystem states
State 1 submodel, plant communities
State 1
Reference State
Community 1.1
Indian ricegrass/Needle and thread
Grasses make up approximately 50 to 75 percent of the total production while forbs are 5 to 10 percent and shrubs make up approximately 20 to 40 percent.
Figure 3. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Grass/Grasslike | 151 | 213 | 269 |
| Shrub/Vine | 62 | 101 | 140 |
| Forb | 11 | 22 | 39 |
| Total | 224 | 336 | 448 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 1-2% |
| Grass/grasslike foliar cover | 12-15% |
| Forb foliar cover | 0-1% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0% |
Table 7. Canopy structure (% cover)
| Height Above Ground (m) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.15 | – | – | – | 3-5% |
| >0.15 <= 0.3 | – | – | 25-30% | – |
| >0.3 <= 0.6 | – | – | – | – |
| >0.6 <= 1.4 | – | 3-5% | – | – |
| >1.4 <= 4 | – | – | – | – |
| >4 <= 12 | – | – | – | – |
| >12 <= 24 | – | – | – | – |
| >24 <= 37 | – | – | – | – |
| >37 | – | – | – | – |
State 2
Degraded State
This State is result of soil-disturbing activities such as hoof-action, anthropogenic activity, and rodent activity. It can also occur after brush management followed by improper grazing techniques that usually include high-intensity grazing without appropriate recovery periods.
Transition T1A
State 1 to 2
The driver for transition T1A from State 1 (Reference State) to State 2 (Degraded) is low to high intensity, long duration, and high frequency herbivory events.
Additional community tables
Table 8. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 168–252 | |||||
| needle and thread | HECOC8 | Hesperostipa comata ssp. comata | 50–135 | – | ||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 34–84 | – | ||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 34–67 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 34–50 | – | ||
| thickspike wheatgrass | ELLAL | Elymus lanceolatus ssp. lanceolatus | 17–34 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–34 | – | ||
| needleleaf sedge | CADU6 | Carex duriuscula | 0–17 | – | ||
| threadleaf sedge | CAFI | Carex filifolia | 0–17 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–17 | – | ||
|
Forb
|
||||||
| 2 | 17–34 | |||||
| tapertip onion | ALAC4 | Allium acuminatum | 0–6 | – | ||
| rosy pussytoes | ANRO2 | Antennaria rosea | 0–6 | – | ||
| Fendler's sandwort | ARFE3 | Arenaria fendleri | 0–6 | – | ||
| freckled milkvetch | ASLE8 | Astragalus lentiginosus | 0–6 | – | ||
| woolly locoweed | ASMO7 | Astragalus mollissimus | 0–6 | – | ||
| wavyleaf Indian paintbrush | CAAPM | Castilleja applegatei ssp. martinii | 0–6 | – | ||
| sego lily | CANU3 | Calochortus nuttallii | 0–6 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 0–6 | – | ||
| roughseed cryptantha | CRFL6 | Cryptantha flavoculata | 0–6 | – | ||
| cushion buckwheat | EROV | Eriogonum ovalifolium | 0–6 | – | ||
| shaggy fleabane | ERPU2 | Erigeron pumilus | 0–6 | – | ||
| rosy gilia | GISI | Gilia sinuata | 0–6 | – | ||
| fernleaf biscuitroot | LODI | Lomatium dissectum | 0–6 | – | ||
| silvery lupine | LUAR3 | Lupinus argenteus | 0–6 | – | ||
| mat penstemon | PECA4 | Penstemon caespitosus | 0–6 | – | ||
| Crandall's beardtongue | PECR5 | Penstemon crandallii | 0–6 | – | ||
| longleaf phlox | PHLO2 | Phlox longifolia | 0–6 | – | ||
| scarlet globemallow | SPCO | Sphaeralcea coccinea | 0–6 | – | ||
| heartleaf twistflower | STCO6 | Streptanthus cordatus | 0–6 | – | ||
| stemless four-nerve daisy | TEAC | Tetraneuris acaulis | 0–6 | – | ||
| hollyleaf clover | TRGY | Trifolium gymnocarpon | 0–6 | – | ||
|
Shrub/Vine
|
||||||
| 3 | 67–135 | |||||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 34–67 | – | ||
| antelope bitterbrush | PUTR2 | Purshia tridentata | 34–50 | – | ||
| spiny hopsage | GRSP | Grayia spinosa | 0–34 | – | ||
| desert princesplume | STPIP | Stanleya pinnata var. pinnata | 0–6 | – | ||
Interpretations
Animal community
WILDLIFE INTERPRETATIONS:
This site is important winter habitat for mule deer and pronghorn. Sage grouse, sage sparrows and many other wildlife species associated with sagebrush communities are also found on the site. Conservation practices that provide water such as ponds can be very beneficial. Brush control and range seeding is detrimental to many sage dependent wildlife species while being beneficial to other species. Brush control practices with less than 75 percent kill are preferable for wildlife. Planned practices should strive for a mosaic of areas in different successional stages from grass to decadent sagebrush to provide for all wildlife species.
Some representative species of sagebrush bunchgrass communities are:
Mule deer
pronghorn
mountain lion
elk
badger
bobcat
coyote
Nuttall's cottontail
white-tailed jackrabbit
mourning dove
sage grouse
green-tailed townee
Brewer's sparrow
sage sparrow
sage thrasher
red-tailed hawk
ferruginous hawk
golden eagle
sagebrush vole
deer mouse
white-tailed prairie dog
Richardson's ground squirrel
Great Basin spadefoot
tiger salamander
sagebrush lizard
Eastern fence lizard
side-blotched lizard
western rattlesnake
striped whipsnake
bull snake
GRAZING INTERPRETATIONS:
Stocking rates given below are based on continuous use for the entire growing season and are intended only as an initial guide. About 20 to 40 percent of the total production (by air-dry weight) will likely be unpalatable or out of reach of grazing animals. Forage needs are calculated on the basis of 900 pounds of air-dry forage per animal unit month (AUM). To maintain proper use and allow for forage that disappears through trampling, small herbivore use, weathering, etc., 35 percent of the palatable forage produced is considered available for grazing by large herbivores.
Excellent (76-100%) .13-.12AUM/Ac; 7-8 Ac/AUM; 84-96Ac/AU
Good (51-75%) .12-.10 AUM/Ac; 9-10 Ac/AUM; 108-120 Ac/AU
Fair (26-50%) .09-.05 AUM/Ac; 11-20 Ac/AUM; 132-240 Ac/AU
Poor (0-25%) .04-.01 AUM/Ac; No grazing recommended.
Adjustments to the initial stocking rates should be made as needed to obtain proper use. With specialized grazing systems, large livestock breeds, uncontrolled big game, inaccessibility, dormant season use, presence of introduced forage species, seeded rangeland etc., will require stocking rate adjustments.
Grazing value of this site even in climax condition, is fairly low due to low production. Extreme care needs to be exercised to prevent accelerated soil erosion. Any Utah juniper and pinyon pine present on this site should be cut or killed. Severe erosion occurs on this site when juniper and pinyon pine gain dominance. A planned grazing system that provides deferment from grazing at least 75 percent of the time during the growing season can help to maintain and improve the vegetation on this site.
Hydrological functions
Soils in this site are grouped into the "D" hydrologic group, as outlined in the Soils of Colorado Loss Factors and Erodibility Hydrologic Groupings 1979 Handbook. Field investigations are needed to determine hydrologic cover conditions and hydrologic curve numbers. Refer to NRCS National Engineering Handbook, Section 4, and Peak Flows in Colorado Handbook for more information.
Recreational uses
The site has some potential for recreation and natural beauty. The forbs bloom in the spring which can be very attractive. The site offers good hunting in the fall.
Wood products
The site when in climax condition, is treeless. There is no potential for wood products under these condiions. If trees have invaded onto the site, they should be harvested for firewood, fence posts, fence stays, and Christmas trees or destroyed because of the erosion hazard that the trees create on this soil.
Other information
Endangered Plants and Animals:
Areas of this site that contain white-tailed prairie dogs are potential black-footed ferret habitat.
Supporting information
Inventory data references
Information presented here has been derived from NRCS clipping data and other inventory data. Field observations from range trained personnel were also used. Other sources used as references include: USDA NRCS Water and Climate Center, USDA NRCS National Range and Pasture Handbook, and USDA NRCS Soil Surveys from various counties.
Type locality
| Location 1: Moffat County, CO |
|---|
Other references
Belnap, J. and S. L. Phillips. 2001. Soil biota in an ungrazed grassland: Response to annual grass (Bromus tectorum) invasion. Ecological Applications: 11: 1261-1275.
Caudle, D., H. Sanchez, J. DiBenedetto, C. Talbot, and M. Karl. 2013. Draft Interagency Ecological Site Handbook for Rangelands. US Dept. of Agriculture. Washington D.C
Cleland, D.T.; Freeouf, J.A.; Keys, J.E., Jr.; Nowacki, G.J.; Carpenter, C; McNab, W.H. 2007. Ecological Subregions: Sections and Subsections of the Conterminous United States.[1:3,500,000], Sloan, A.M., cartog. Gen. Tech. Report WO-76. Washington, DC: U.S. Department of Agriculture, Forest Service.
Musgrave, G.W. 1955. How much of the rain enters the soil? In Water: U.S. Department of Agriculture Yearbook. Washington, D.C. P. 151-159.
National Engineering Handbook. US Department of Agriculture, Natural Resources Conservation Service. Available: http://www.info.usda.gov/CED/Default.cfm#National%20Engineering%20Handbook. Accessed February 25, 2008.
Passey, H. B., W. K. Hugie, E. W. Williams, and D. E. Ball. 1982. Relationships between soil, plant community, and climate on rangelands of the Intermountain west. USDA, Soil Conservation Service, Tech. Bull. No. 1669.
Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov/. Accessed [8/10/2015].
United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.
Western Regional Climate Center. Retrieved from http://www.wrcc.dri.edu/summary/Climsmco.html on May 17, 2018.
Contributors
JWK, LJJ
Approval
Kirt Walstad, 9/07/2023
Acknowledgments
Counties where this site occurs:
Moffat
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
| Author(s)/participant(s) | |
|---|---|
| Contact for lead author | |
| Date | 11/23/2024 |
| Approved by | Kirt Walstad |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
-
Presence of water flow patterns:
-
Number and height of erosional pedestals or terracettes:
-
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
-
Number of gullies and erosion associated with gullies:
-
Extent of wind scoured, blowouts and/or depositional areas:
-
Amount of litter movement (describe size and distance expected to travel):
-
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
-
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
-
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
-
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
-
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
-
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
-
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
-
Perennial plant reproductive capability:
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