Natural Resources
Conservation Service
Ecological site R023XY608OR
DROUGHTY PUMICE PLAINS 8-11 PZ
Last updated: 4/10/2025
Accessed: 04/11/2025
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.
Ecological site concept
Currently there is only a draft of the initial concept for this ecological site. The initial concept for this site places it within the Clayey Mesic Plateaus 8-14 PZ Wyoming Big Sagebrush and Thurber's Needlegrass Ecological Site Group. To view the General STM and other information available for this ESG please go to https://edit.jornada.nmsu.edu/catalogs/esg/023X/R023XY909OR
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
Not specified |
Physiographic features
This site occurs on terraces and plains in old lake basins. Occasionally, It occurs in swales and small valleys within hill topography.
Table 2. Representative physiographic features
| Landforms |
(1)
Terrace
(2) Plain (3) Swale |
|---|---|
| Elevation | 4,300 – 4,800 ft |
| Slope | 3% |
| Aspect | Aspect is not a significant factor |
Climatic features
Most of the annual precipitation occurs during the months of October through March. The soil temperature regime is marginal for frigid. The mean annual air temperature is 48 degrees F. Temperature extremes range from 110 to -30 degrees F. The period for optimum Plant growth is from April through early June. Some fall growth may occur during October-November when these months are unusually warm and moist.
Table 3. Representative climatic features
| Frost-free period (average) | 70 days |
|---|---|
| Freeze-free period (average) | 100 days |
| Precipitation total (average) | 11 in |
Influencing water features
Soil features
The soils of this site are typically moderately deep or deep (rarely shallow), well to somewhat excessively drained and sandy loam to gravely, loamy sand textured. They are generally formed in/from wind deposited volcanic ash/pumice and lacustrine deposits. Permeability is rapid to very rapid, and the available water holding capacity is typically 3-7 inches for the profile. The potential for water erosion is low and wind erosion is high.
Table 4. Representative soil features
| Surface texture |
(1) Sandy loam (2) Gravelly loamy sand |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained to somewhat excessively drained |
| Permeability class | Rapid to very rapid |
| Soil depth | 60 – 100 in |
| Available water capacity (0-40in) |
3 – 7 in |
| Calcium carbonate equivalent (0-40in) |
2% |
| Electrical conductivity (0-40in) |
Not specified |
| Sodium adsorption ratio (0-40in) |
Not specified |
| Soil reaction (1:1 water) (0-40in) |
7 |
Ecological dynamics
The potential native plant community is dominated by basin big sagebrush and needleandthread. Gray rabbit brush and granite pricklygilia are also common in the stand. Minor amounts of other woody plants are present including low green rabbitbrush and granite pricklygilia. Indian ricegrass, Ross sedge, squirreltail and Thurber needlegrass are common. Minor occurrences of basin wildrye or thickspike wheatgrass are sometimes present. Vegetative composition by weight is approximately 65-70% grasses, 5-10% forbs, and 20-25% shrubs.
State and transition model
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Ecosystem states
State 1 submodel, plant communities
State 1
State A: HCPC
Community 1.1
State A: HCPC
Figure 1. 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 | 650 | 675 | 700 |
| Shrub/Vine | 200 | 225 | 250 |
| Forb | 50 | 75 | 100 |
| Total | 900 | 975 | 1050 |
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 | 303–438 | |||||
| needle and thread | HECO26 | Hesperostipa comata | 303–438 | – | ||
| 2 | 53–100 | |||||
| western needlegrass | ACOCO | Achnatherum occidentale ssp. occidentale | 33–47 | – | ||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 13–33 | – | ||
| Thurber's needlegrass | ACTH7 | Achnatherum thurberianum | 7–20 | – | ||
| 3 | 7–20 | |||||
| squirreltail | ELEL5 | Elymus elymoides | 7–20 | – | ||
| 4 | 0–52 | |||||
| Idaho fescue | FEID | Festuca idahoensis | 0–13 | – | ||
| basin wildrye | LECI4 | Leymus cinereus | 0–13 | – | ||
| beardless wildrye | LETR5 | Leymus triticoides | 0–13 | – | ||
| bluebunch wheatgrass | PSSPS | Pseudoroegneria spicata ssp. spicata | 0–13 | – | ||
| 5 | 13–33 | |||||
| Ross' sedge | CARO5 | Carex rossii | 13–33 | – | ||
|
Forb
|
||||||
| 6 | 7–21 | |||||
| rockcress | ARABI2 | Arabis | 1–3 | – | ||
| woollypod milkvetch | ASPU9 | Astragalus purshii | 1–3 | – | ||
| milkvetch | ASTRA | Astragalus | 1–3 | – | ||
| Douglas' dustymaiden | CHDO | Chaenactis douglasii | 1–3 | – | ||
| blue eyed Mary | COLLI | Collinsia | 1–3 | – | ||
| Cascade knotweed | POCA9 | Polygonum cascadense | 1–3 | – | ||
|
Shrub/Vine
|
||||||
| 7 | 39–67 | |||||
| basin big sagebrush | ARTRT | Artemisia tridentata ssp. tridentata | 34–56 | – | ||
| rubber rabbitbrush | ERNA10 | Ericameria nauseosa | 5–11 | – | ||
| 8 | 10–25 | |||||
| mountain big sagebrush | ARTRV | Artemisia tridentata ssp. vaseyana | 2–5 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 2–5 | – | ||
| spineless horsebrush | TECA2 | Tetradymia canescens | 2–5 | – | ||
Interpretations
Supporting information
Contributors
C Tackman
Approval
Kendra Moseley, 4/10/2025
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 | 04/11/2025 |
| Approved by | Kendra Moseley |
| 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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