Natural Resources
Conservation Service
Ecological site R030XB079NV
GYPSIC SLOPE 3-5 P.Z.
Last updated: 3/11/2025
Accessed: 06/18/2026
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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
This site occurs on fan piedmonts, alluvial fans and alluvial plains on all exposures. Slopes range from 0 to 15 percent, but slope gradients of 2 to 8 percent are most typical. Elevations are 1500 to about 3000 feet. The soil associated with this site are deep and very high in gypsum. They are somewhat excessively drained and formed in residuum and colluvium from gypsiferous sedimentary rocks.
Please refer to group concept R030XB104NV to view the provisional STM.Associated sites
R030XB019NV Eroded Fan Remnant Pavette 4-6 P.Z.
Similar sites
R030XB109NV GYPSIC BARREN 3-5 P.Z.
PSFR & PEPA13 codominant shrubs
R030XB117NV GYPSIC SAND 3-5 P.Z.
PSFR dominant shrub; ATCA2 major shrub; ATHY rare to absent
R030XB026NV GYPSIC LOAM 3-5 P.Z.
PSFR codominant shrub; PEPA13 important shrub
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Atriplex hymenelytra
(2) SuaedaHerbaceous Not specified
Physiographic features
This site occurs on fan piedmonts, alluvial fans and alluvial plains on all exposures. Slopes range from 0 to 15 percent, but slope gradients of 2 to 8 percent are most typical. Elevations are 1500 to about 3000 feet.
Table 2. Representative physiographic features
Landforms (1) Fan piedmont
(2) Alluvial fan
(3) Alluvial flat
Elevation 1500 – 3000 ft Slope 0 – 15 % Climatic features
The climate is hot and arid, with mild winters and very hot summers. Precipitation is greatest in the winter with a lesser secondary peak in summer, typical of the Mojave Desert. Average annual precipitation is 3 inches or less. Mean annual air temperature is 65 to 76 degrees F. The average growing season is about 270 to 360 days.
Table 3 Representative climatic features
Frost-free period (average) 360 days Freeze-free period (average) Precipitation total (average) 0 in ">Influencing water features
There are no influencing water features associated with this site.
Soil features
The soil associated with this site are deep and very high in gypsum. They are somewhat excessively drained and formed in residuum and colluvium from gypsiferous sedimentary rocks. Permeability is moderately rapid, available water capacity is moderate to high, and runoff is medium. The soils are usually dry, but are moist for short periods in winter and spring, and moist for 10 to 20 days intermittently in the summer. The soils have a thermic temperature regime and a typic aridic moisture regime. The soils have an ochric epipedon and a gypsic horizon. There are identifiable secondary carbonates from 2 to 49 inches.
The soil series correlated to this site is Bracken, a coarse-loamy, gypsic, thermic Leptic Haplogypsid.Table 4. Representative soil features
Parent material (1) Colluvium – rock gypsum
Surface texture (1) Material
Family particle size (1) Loamy
Drainage class Somewhat excessively drained Permeability class Moderately rapid Soil depth 48 – 49 in Surface fragment cover <=3" 35 – 40 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)5 – 7 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)7.8 – 7.9 Subsurface fragment volume <=3"
(Depth not specified)0 – 30 % Subsurface fragment volume >3"
(Depth not specified)Not specified Ecological dynamics
Please refer to group concept R030XB104NV to view the provisional STM.
As ecological condition deteriorates, total shrub canopy decreases and large openings develop between individual shrubs. Few introduced annual forbs or grasses (red brome, Mediterranean grass, African mustard) will invade this site.State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Reference Plant CommunityCommunity 1.1
Reference Plant CommunityThe reference plant community is dominated by desert holly and Suaeda spp.
Potential vegetative composition is about 10% annual and perennial native forbs, 10% grasses and 80% shrubs. Approximate ground cover (basal and crown) is less than 5 percent.
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)Shrub/Vine 1 40 64 Grass/Grasslike 0 5 8 Forb 0 5 8 Total 1 50 80 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Perennial grasses 1–3 Indian ricegrass ACHY Achnatherum hymenoides 0–2 – low woollygrass DAPU7 Dasyochloa pulchella 0–2 – big galleta PLRI3 Pleuraphis rigida 0–2 – Forb2 Perennial forbs 5–10 3 Annual forbs 1–8 Shrub/Vine4 Primary shrubs 16–64 desertholly ATHY Atriplex hymenelytra 4–36 – desert-thorn LYCIU Lycium 8–16 – seepweed SUAED Suaeda 8–16 – 5 Secondary shrubs 4–12 desert pepperweed LEFR2 Lepidium fremontii 1–3 – Interpretations
Animal community
Livestock Interpretations:
This site has limited value for livestock grazing, due to the low forage production.
Stocking rates vary over time depending upon season of use, climate variations, site, and previous and current management goals. A safe starting stocking rate is an estimated stocking rate that is fine tuned by the client by adaptive management through the year and from year to year.Hydrological functions
Water intake rates are slow, available water capacity is moderate to high, runoff is rapid, and the soils are well drained.
Supporting information
Other references
Fire Effects Information System (Online; http://www.fs.fed.us/database/feis/plants/).
USDA-NRCS Plants Database (Online; http://www.plants.usda.gov).
Contributors
RWA
Approval
Kendra Moseley, 3/11/2025
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) P NOVAK-ECHENIQUE Contact for lead author State Rangeland Management Specialist Date 05/15/2013 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
Rills are none to rare. A few may occur on steeper slopes after summer convection storms. -
Presence of water flow patterns:
Water flow patterns are none to rare. A few (short <1m and stable) may occur on steeper slopes after summer convection storms. -
Number and height of erosional pedestals or terracettes:
None -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground is variable (40-60%) depending on amount of surface rock fragments -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None -
Amount of litter movement (describe size and distance expected to travel):
Litter typically remains in place. Fine litter (foliage from grasses and annual & perennial forbs) may move the distance of slope length during intense summer convection storms or rapid snowmelt events. Persistent litter (large woody material) will remain in place except during large rainfall events. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil stability values should be 1 to 3. (To be field tested.) -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil surface structure is typically weak coarse platy. Soil surface colors are pale browns and the soils have an ochric epipedon. Organic matter of the surface 2 to 3 inches is less than 1 percent. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Sparse shrub canopy and associated litter break provide some protection from raindrop impact. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. Massive or gypsic sub-surface horizons are not to be interpreted as compacted layers. -
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:
salt-desert shrubsSub-dominant:
perennial forbs > perennial grasses > annual forbs > annual grassesOther:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Dead branches within individual shrubs are common and standing dead shrub canopy material may be as much as 25% of total woody canopy. -
Average percent litter cover (%) and depth ( in):
Between plant interspaces (trace) and depth (<¼-inch). Litter is concentrated under shrubs and generally stays in place. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season ~50lbs/ac. Favorable years ~80 lbs. Little growth during drought years. -
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:
Potential invaders include red brome, red-stem filaree, mustards, and Mediterranean grass. -
Perennial plant reproductive capability:
All functional groups should reproduce in normal and above-normal rainfall years .Little growth or reproduction during drought years.
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