
Natural Resources
Conservation Service
Ecological site R030XB095NV
SHALLOW VOLCANIC HILL 5-7 P.Z.
Last updated: 3/10/2025
Accessed: 03/16/2025
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
This site occurs on summits and sideslopes of rolling hills. Slopes gradients of 15 to 50 percent are typical. Elevations are 2000 to about 3500 feet. The soil associated with this site are shallow and have formed in residuum and colluvium from volcanic parent material.
Please refer to group concept R030XB072NV to view the provisional STM.
Associated sites
R030XB070NV |
VOLCANIC HILL 5-7 P.Z. |
---|---|
R030XB071NV |
VOLCANIC SLOPE 7-9 P.Z. |
Similar sites
R030XB070NV |
VOLCANIC HILL 5-7 P.Z. ERFAP-AMDU2 codominant |
---|---|
R030XB008NV |
SHALLOW GRANITIC HILL 5-7 P.Z. Soils from granitic PM |
R030XB071NV |
VOLCANIC SLOPE 7-9 P.Z. more productive site |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
(1) Eriogonum fasciculatum |
Herbaceous |
(1) Achnatherum speciosum |
Physiographic features
This site occurs on summits and sideslopes of rolling hills. Slopes gradients of 15 to 50 percent are typical. Elevations are 2000 to about 3500 feet.
Table 2. Representative physiographic features
Landforms |
(1)
Hill
|
---|---|
Elevation | 2,000 – 3,500 ft |
Slope | 15 – 50% |
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 5 to 7 inches. Mean annual air temperature is 63 to 66 degrees F. The average growing season is about 200 to 280 days.
Table 3. Representative climatic features
Frost-free period (average) | 280 days |
---|---|
Freeze-free period (average) | |
Precipitation total (average) | 7 in |
Influencing water features
There are no influencing water features associated with this site.
Soil features
The soil associated with this site are shallow and have formed in residuum and colluvium from volcanic parent material. These soils have a surface cover of gravel-size rock fragments in excess of 45 percent. Total ground surface cover of rock fragments is typically greater than 60 percent. Available water capacity is low and runoff is medium to rapid.
Ecological dynamics
Please refer to group concept R030XB072NV to view the provisional STM.
As ecological condition deteriorates, perennial grasses and forbs decrease as shrub species become more dominant. Introduced annual forbs and grasses readily invade this site.
Fire Ecology:
Most fires in the Mojave desert are infrequent and of low severity because production of annual and perennial herbs seldom provides a fuel load capable of sustaining fire. Fires in creosotebush scrub were an infrequent event in pre-settlement desert habitats, because fine fuels from winter annual plants were probably sparse, only occurring in large amounts during exceptionally wet winters. Fire kills many creosotebush. Creosotebush is poorly adapted to fire because of its limited sprouting ability. Creosotebush survives some fires that burn patchily or are of low severity. Mojave buckwheat is vulnerable to hot fires. Resprout success is low and most regeneration is from seeds. Frequent fires deplete the seed bank, making populations vulnerable to extinction. Following fire, Virgin River encelia depends on off-site seed rather than on-site sprouts for regeneration. Range ratany is top-killed by fire. Range ratany resprouts from the root crown after fire. Nevada ephedra is top-killed by fire. Underground regenerative structures commonly survive when aboveground vegetation is consumed by fire. Nevada ephedra generally sprouts after fire damages aboveground vegetation and may increase in plant cover. Desert needlegrass has persistent dead leaf bases, which make it susceptible to burning. Fire removes the accumulation; a rapid, cool fire will not burn deep into the root crown and surviving tufts will resprout. Fire most likely top-kills big galleta. Big galleta sprouts from rhizomes following fire. Damage to big galleta from fire varies, depending on whether big galleta is dormant when burned. If big galleta is dry, damage may be severe. However, when plants are green, fire will tend to be less severe and damage may be minimal, with big galleta recovering quickly.
State and transition model
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Ecosystem states
State 1 submodel, plant communities
State 1
Reference Plant Community
Community 1.1
Reference Plant Community
The reference plant community is dominated by Mojave buckwheat. Potential vegetative composition is about 15% grasses, 10% annual and perennial forbs and 75% shrubs. Approximate ground cover (basal and crown) is less than 10 percent.
Figure 1. Annual production by plant type (representative values) or group (midpoint values)
Table 4. Annual production by plant type
Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
---|---|---|---|
Shrub/Vine | 75 | 169 | 263 |
Grass/Grasslike | 15 | 34 | 52 |
Forb | 10 | 22 | 35 |
Total | 100 | 225 | 350 |
Additional community tables
Table 5. Community 1.1 plant community composition
Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
---|---|---|---|---|---|---|
Grass/Grasslike
|
||||||
1 | Primary Perennial Grasses | 10–36 | ||||
desert needlegrass | ACSP12 | Achnatherum speciosum | 5–18 | – | ||
big galleta | PLRI3 | Pleuraphis rigida | 5–18 | – | ||
2 | Secondary Perennial Grasses | 9–11 | ||||
Indian ricegrass | ACHY | Achnatherum hymenoides | 1–7 | – | ||
threeawn | ARIST | Aristida | 1–7 | – | ||
low woollygrass | DAPU7 | Dasyochloa pulchella | 1–7 | – | ||
bush muhly | MUPO2 | Muhlenbergia porteri | 1–7 | – | ||
3 | Annual Grasses | 1–11 | ||||
Forb
|
||||||
4 | Primary Perennial forbs | 2–11 | ||||
desert globemallow | SPAM2 | Sphaeralcea ambigua | 2–11 | – | ||
5 | Perennial forbs | 5–11 | ||||
6 | Annual forbs | 1–23 | ||||
Shrub/Vine
|
||||||
7 | Primary shrubs | 127–216 | ||||
Eastern Mojave buckwheat | ERFAP | Eriogonum fasciculatum var. polifolium | 100–135 | – | ||
creosote bush | LATR2 | Larrea tridentata | 11–23 | – | ||
Virgin River brittlebush | ENVI | Encelia virginensis | 5–18 | – | ||
Nevada jointfir | EPNE | Ephedra nevadensis | 5–11 | – | ||
Parish's goldeneye | VIPA14 | Viguiera parishii | 1–11 | – | ||
8 | Secondary shrubs | 23–45 | ||||
catclaw acacia | ACGR | Acacia greggii | 2–11 | – | ||
burrobush | AMDU2 | Ambrosia dumosa | 2–11 | – | ||
brittlebush | ENFA | Encelia farinosa | 2–11 | – | ||
spiny menodora | MESP2 | Menodora spinescens | 2–11 | – | ||
Fremont's dalea | PSFR | Psorothamnus fremontii | 2–11 | – | ||
Mojave yucca | YUSC2 | Yucca schidigera | 2–11 | – |
Interpretations
Animal community
Livestock Interpretations:
This site has limited value for livestock grazing, due to the low forage production, steep slopes and stony surfaces. Desert needlegrass produces considerable basal foliage and is good forage while young. Young desert needlegrass is palatable to all classes of livestock. Mature herbage is moderately grazed by horses and cattle but rarely grazed by sheep. Mojave buckwheat has a browse rating of fair to poor for cattle. Creosotebush is unpalatable to livestock. Consumption of creosotebush may be fatal to sheep. Encelia has no forage value for domestic livestock. Range ratany is an important forage species for all classes of livestock. Palatability of range ratany is rated fair to good for cattle and sheep. Nevada ephedra is important winter range browse for domestic cattle, sheep and goats. Nevada ephedra is usually grazed heavily and seems to be perfectly safe for grazing livestock since it induces neither toxicity in ewes or cows, nor congenital deformities in lambs. Triangle goldeneye has limited browse value, when other forage is scarce, but otherwise are practically worthless as forage except that livestock will frequently pick off the flowering and fruiting heads, after frost, and nibble the leaves.
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.
Wildlife Interpretations:
Creosotebush is unpalatable to most browsing wildlife. Virgin River encelia is important to the desert tortoise as a source of succulent forage in periods of low moisture. Encelia is a browse species of desert mule deer and desert bighorn Sheep. Range ratany is an important forage species for deer. Mule deer browse range ratany year-long with seasonal peaks. Mule deer peak use is from February to April and from August to October. Mule deer, bighorn sheep, and pronghorn browse Nevada ephedra, especially in spring and late summer when new growth is available. Mountain quail eat Ephedra seeds. Triangle goldeneye has limited browse value, when other forage is scarce, but otherwise are practically worthless as forage. Desert bighorn sheep and feral horses and burros will graze desert needlegrass.
Hydrological functions
Available water capacity is low and runoff is medium to rapid.
Other products
Creosotebush has been highly valued for its medicinal properties by Native Americans. It has been used to treat at least 14 illnesses. Twigs and leaves may be boiled as tea, steamed, pounded into a powder, pressed into a poultice, or heated into an infusion. The Papago Indians used an infusion of range ratany twigs externally for treating sore eyes and internally for dysentery. The roots provided them with a red dye for wool and other materials. The dye was also used as an ink. Some Native American tribes steeped the twigs of Nevada ephedra and drank the tea as a general beverage.
Other information
Desert needlegrass may be used for groundcover in areas of light disturbance, but it is susceptible to excessive trampling. Once established, creosotebush may improve sites for annuals that grow under its canopy by trapping fine soil, organic matter, and symbiont propagules. It may also increase water infiltration and storage.
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
GKB
Approval
Kendra Moseley, 3/10/2025
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 | 03/11/2025 |
Approved by | Sarah Quistberg |
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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