Natural Resources
Conservation Service
Ecological site R023XY220OR
CLAYEY 10-12 PZ
Accessed: 12/22/2024
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.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
Associated sites
| R023XY200OR |
PONDED CLAY Ponded Clay |
|---|---|
| R023XY212OR |
LOAMY 10-12 PZ Loamy 10-12" PZ |
| R023XY214OR |
CLAYPAN 10-12 PZ Claypan 10-12" PZ |
Similar sites
| R023XY212OR |
LOAMY 10-12 PZ Loamy 10-12" PZ (lacks a clayey argillic horizon) |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Artemisia tridentata ssp. wyomingensis |
| Herbaceous |
(1) Pseudoroegneria spicata |
Physiographic features
This site occurs on terraces, rolling uplands, and mountain foothills. Slopes range from 0 to 30 percent, but gradients of 2 to 20 percent are most typical. Elevations range from 4500 to 6000 feet.
Table 2. Representative physiographic features
| Landforms |
(1)
Plateau
(2) Hill |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 4,500 – 6,000 ft |
| Slope | 2 – 20% |
| Aspect | Aspect is not a significant factor |
Climatic features
The annual precipitation ranges from 10 to 12 inches, most of which occurs in the form of snow during the months of December through February. Spring rains are common. The soil temperature regime is frigid. Extreme temperatures range from 100 degrees F to -30 degrees F. The frost-free period is from 50 to 90 days. The optimum period for plant growth is mid-April through June.
Table 3. Representative climatic features
| Frost-free period (average) | 90 days |
|---|---|
| Freeze-free period (average) | 0 days |
| Precipitation total (average) | 12 in |
Influencing water features
Soil features
The soils of this site are shallow to deep over bedrock but a fine textured layer (clay) is present below a depth of about 8 or 10 inches. Surface textures are typically loam or clay loam with subsoil textures of clay and/or silty clay. The soils are well-drained and permeability is slow to very slow. When this site is on old terraces, rock fragments on the surface are absent. When this site is on uplands or foothills (which is most typical) the percent of rock fragments (primarily cobbles and stones) range from 15 to 60 percent. The available water holding capacity (AWC) is 1 to 5 inches for the profile. Water erosion hazard is moderate.
Table 4. Representative soil features
| Parent material |
(1)
Colluvium
–
basalt
(2) Residuum – welded tuff |
|---|---|
| Surface texture |
(1) Cobbly loam (2) Very cobbly clay loam (3) Silt loam |
| Family particle size |
(1) Clayey |
| Drainage class | Well drained |
| Permeability class | Slow to very slow |
| Soil depth | 12 – 40 in |
| Surface fragment cover <=3" | 8 – 23% |
| Surface fragment cover >3" | 29% |
| Available water capacity (0-40in) |
0.8 – 4.8 in |
| Calcium carbonate equivalent (0-40in) |
Not specified |
| Electrical conductivity (0-40in) |
Not specified |
| Sodium adsorption ratio (0-40in) |
Not specified |
| Soil reaction (1:1 water) (0-40in) |
6.6 – 7.8 |
| Subsurface fragment volume <=3" (Depth not specified) |
15 – 29% |
| Subsurface fragment volume >3" (Depth not specified) |
5 – 17% |
Ecological dynamics
Range in Characteristics:
Variability in production and composition on a site result from variation in soil depth and texture. Restrictive layers (claypan) within 20 inches of the soil surface will reduce production. Gravels in the surface layer or a decrease in clay in the subsoil will favor the presence of Thurber needlegrass in the stand. If significant soil loss occurs on this site, it will grade into the Claypan 10-12" PZ site.
Four states have been identified for this site: a reference state; a state with the presence of annuals; a state with a shrub/annual co-dominance; and a state with annual dominance.
Reference State: Plant community phase change is driven by infrequent fire. Wyoming and basin big sagebrush decline after fire while Thurber’s needlegrass, Indian ricegrass and other grasses increase. Rabbitbrush may temporarily increase after fire. Time facilitates the reintroduction of sagebrush. The introduction of invasive annual grasses and forbs transitions into state 2.
State 2: Compositionally similar to the reference state with a trace of cheatgrass and weedy forbs. Ecological function has not changed, however the resiliency of the state has been reduced by the presence of invasive weeds. Prescribed grazing and infrequent fire (> 50 year return interval) maintain state dynamics. The timing and/or intensity of grazing or prolonged drought favors Wyoming and basin big sagebrush, squirreltail and Sandberg’s bluegrass. Prescribed grazing and/or release from drought may reverse the decline in needlegrass and Indian ricegrass production. Infrequent fire reduces the shrub community and promotes the bunchgrass component. Mismanaged grazing and/or prolonged drought leads to a biotic threshold and into state 3.
State 3: Wyoming and basin big sagebrush is decadent with little recruitment. The perennial grass component is significantly reduced in both density and productivity. Cheatgrass and/or annual forbs and/or Sandberg’s bluegrass along with sagebrush control site resources and drive ecological dynamics. Bare ground is abundant. Spatial and temporal energy capture and nutrient cycling has been truncated. Infiltration may be reduced due to lack of ground cover. Risk of soil erosion by both wind and water is increased. Catastrophic wildfire will lead to an abiotic threshold and into state 4.
State 4: Cheatgrass and/or annual weed dominated plant community with limited to no shrub or perennial grass component. Soil erosion and redistribution along with changes in dynamic soil properties affect the hydrologic cycle and thus the nutrient cycle. Harsh environmental factors increase state resiliency to change.
Response to Disturbance:
If heavy grazing causes site deterioration, big sagebrush and rabbitbrush become dominant. Sandberg bluegrass, bottlebrush squirreltail, and forbs will increase in the understory. This site (with frigid soils) is less susceptible to cheatgrass invasion, but it can occur. Annual forbs will invade this site. As conditions deteriorate, the amount of bare ground will also increase.
State and transition model
Figure 2. Group 6, STM
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Ecosystem states
State 1 submodel, plant communities
State 1
Reference State
Community 1.1
Reference Plant Community
The potential native plant community is dominated by bluebunch wheatgrass and Wyoming big sagebrush. Thurber needlegrass and Sandberg bluegrass occur commonly on the stand. Vegetative composition is about 75 percent grass, 10 percent forbs, and 15 percent shrubs. Approximate ground cover is 15 to 25 percent (basal and crown).
Figure 3. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 525 | 675 | 900 |
| Shrub/Vine | 105 | 135 | 180 |
| Forb | 70 | 90 | 120 |
| Total | 700 | 900 | 1200 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Perennial, deep-rooted, bunch-grass | 450–630 | ||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 450–630 | – | ||
| 2 | Perennial, deep-rooted, bunch-grass | 63–180 | ||||
| Thurber's needlegrass | ACTH7 | Achnatherum thurberianum | 45–135 | – | ||
| basin wildrye | LECI4 | Leymus cinereus | 18–45 | – | ||
| 4 | Perennial, shallow-rooted, bunch-grass | 63–162 | ||||
| Sandberg bluegrass | POSE | Poa secunda | 45–90 | – | ||
| Cusick's bluegrass | POCU3 | Poa cusickii | 18–72 | – | ||
| 5 | Other Perennial Grasses | 18–90 | ||||
| squirreltail | ELEL5 | Elymus elymoides | 0–18 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–18 | – | ||
| foxtail wheatgrass | PSSA2 | ×Pseudelymus saxicola | 0–18 | – | ||
|
Forb
|
||||||
| 7 | Perennial Forbs | 36–72 | ||||
| milkvetch | ASTRA | Astragalus | 9–18 | – | ||
| balsamroot | BALSA | Balsamorhiza | 9–18 | – | ||
| hawksbeard | CREPI | Crepis | 9–18 | – | ||
| lupine | LUPIN | Lupinus | 9–18 | – | ||
| 9 | Other perennial forbs | 9–45 | ||||
| agoseris | AGOSE | Agoseris | 0–9 | – | ||
| mariposa lily | CALOC | Calochortus | 0–9 | – | ||
| Indian paintbrush | CASTI2 | Castilleja | 0–9 | – | ||
| Douglas' dustymaiden | CHDOD | Chaenactis douglasii var. douglasii | 0–9 | – | ||
| fleabane | ERIGE2 | Erigeron | 0–9 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–9 | – | ||
| Lava aster | IOAL | Ionactis alpina | 0–9 | – | ||
| beardtongue | PENST | Penstemon | 0–9 | – | ||
| phlox | PHLOX | Phlox | 0–9 | – | ||
| ragwort | SENEC | Senecio | 0–9 | – | ||
|
Shrub/Vine
|
||||||
| 11 | Evergreen | 63–135 | ||||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 45–90 | – | ||
| basin big sagebrush | ARTRT | Artemisia tridentata ssp. tridentata | 18–45 | – | ||
| 15 | Other shrubs | 18–45 | ||||
| rabbitbrush | CHRYS9 | Chrysothamnus | 0–18 | – | ||
| slender buckwheat | ERMI4 | Eriogonum microthecum | 0–18 | – | ||
| horsebrush | TETRA3 | Tetradymia | 0–18 | – | ||
Interpretations
Animal community
Livestock Grazing:
This site is suited to livestock use in all seasons under a planned grazing system.
Native Wildlife Associated with the Potential Climax Community:
Mule deer
Pronghorn antelope
Sage grouse
Hydrological functions
The soils of this site have medium infiltration rates and moderate runoff potential. The hydrologic soil groups are C and D.
Wood products
This site is susceptible to invasion by western juniper. In this event, the site is capable of producing fence posts and firewood.
Supporting information
Contributors
Bob Gillaspy
HB/RC
M. Parks (OSU)
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) | Jeff Repp and Bruce Frannsen |
|---|---|
| Contact for lead author | State Rangeland Management Specialist for NRCS - OR |
| Date | 08/16/2012 |
| Approved by | Bob Gillaspy |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
None, Moderate sheet & rill erosion hazard -
Presence of water flow patterns:
None -
Number and height of erosional pedestals or terracettes:
None to very few pedestals -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
15-40% -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None, Slight wind erosion hazard -
Amount of litter movement (describe size and distance expected to travel):
Fine - limited movement -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Moderately resistant to erosion: aggregate stability = 3-5 -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Shallow to deep well drained loams or clay loams, 15-60% surface fragments: Moderate OM (2-4%) -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Low ground cover (15-25%) and gentle to moderate slopes (0-30%) slightly to moderately limit rainfall impact and overland flow -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None -
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:
Bluebunch wheatgrass > Thurber needlegrass > other grasses > shrubs > forbsSub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Normal decadence and mortality expected -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Favorable: 1000, Normal: 700, Unfavorable: 500 lbs/acre/year at high RSI (RPC) -
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:
Western Juniper readily invades the site. Cheatgrass and Medusahead invade sites that have lost deep rooted perennial grass functional groups. -
Perennial plant reproductive capability:
All species should be capable of reproducing annually
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