Natural Resources
Conservation Service
Ecological site R040XD017CA
Steep Granitic Slope 4-6" p.z.
Accessed: 11/21/2024
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.
Classification relationships
Sawyer, J.O. and T. Keeler-Wolf. 1995. Manual of California Vegetation - Brittlebush-white bursage series
NDDB/Holland type and status: Sonoran desert scrubs (34000). Sonoran mixed woody scrub (33210 in part) G3 S3. Sonoran mixed woody and succulent scrub (33220 in part) G3 S2.2.
Barry type: G74 G7411211.
Brown Lowe Pase type: 154.113
Cheatham & Haller type: Desert cactus scrub.
Thorne type: Stem-succulent scrub.
WHR type: Desert succulent shrub.
Associated sites
| R040XD015CA |
Limy 4-6" p.z. This site can occur in some of the smaller adjacent drainages. |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Encelia farinosa |
| Herbaceous |
(1) Plantago ovata |
Physiographic features
This site occurs on hillslopes and sideslopes of mountains.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Mountain slope |
|---|---|
| Flooding duration | Very brief (4 to 48 hours) |
| Flooding frequency | None to rare |
| Elevation | 305 – 732 m |
| Slope | 15 – 30% |
| Aspect | Aspect is not a significant factor |
Climatic features
The Colorado Desert of California represents the northwesternmost portion of the Sonoran Desert. The subtropical Colorado Desert results from the descent of cold air which is heated by compression and arrives hot and dry at the earth's surface. Precipitation is frontal in nature during the winter and convectional in the summer. Reduced summer rainfall and high potential evapotranspiration make the Colorado Desert one of the most arid regions in North America. Summer temperatures frequently exceed 105 degrees F. The average annual precipitation ranges from 2 to 6 inches with most falling as rain. Snowfall is rare. Approximately 35% of the annual precipitation occurs from July to September as a result of intense convection storms. Spring months are the windiest.
Table 3. Representative climatic features
| Frost-free period (average) | 360 days |
|---|---|
| Freeze-free period (average) | 360 days |
| Precipitation total (average) | 152 mm |
Figure 1. Monthly average minimum and maximum temperature
Influencing water features
Soil features
This site occurs on hillslopes and mountain slopes. The soils consist of very shallow, somewhat excessively drained soils that formed in residuum and colluvium, dominantly from gneissic sources and of very shallow, somewhat excessively drained soils that formed in residuum and colluvium from granite and metamorphic rocks. Soils series include Goldroad and Stormjade.
Table 4. Representative soil features
| Surface texture |
(1) Very gravelly sandy loam |
|---|---|
| Family particle size |
(1) Sandy |
| Drainage class | Somewhat excessively drained to excessively drained |
| Permeability class | Moderately slow to moderate |
| Soil depth | 3 – 51 cm |
| Surface fragment cover <=3" | 60 – 70% |
| Surface fragment cover >3" | 10 – 89% |
| Available water capacity (0-101.6cm) |
0.2 – 1.88 cm |
| Calcium carbonate equivalent (0-101.6cm) |
0 – 5% |
| Electrical conductivity (0-101.6cm) |
0 – 2 mmhos/cm |
| Sodium adsorption ratio (0-101.6cm) |
0 – 2 |
| Soil reaction (1:1 water) (0-101.6cm) |
7.4 – 8.6 |
| Subsurface fragment volume <=3" (Depth not specified) |
30 – 39% |
| Subsurface fragment volume >3" (Depth not specified) |
2 – 3% |
Ecological dynamics
When this site becomes degraded, it looses its tall, shallow-rooted plants first. This includes teddybear cholla (Cylindropuntia bigelovii) and ocotillo (Fouquieria splendens), both of which do not root-sprout. Since the site occurs on steep slopes, the loss of plant cover would result in significant erosion of the soil surface, possibly causing rock slides. Site degradation also invites shorter-lived perennials to dominate the site, such as white bursage (Ambrosia dumosa), mojave woodyaster (Xylohriza tortifolia), and white ratany (Krameria grayi).
State and transition model
More interactive model formats are also available.
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Ecosystem states
State 1 submodel, plant communities
State 1
White brittlebush-teddybear cholla series
Community 1.1
White brittlebush-teddybear cholla series
The interpretative plant community is the historic climax community prior to European colonization. This plant community occurs on steep granitic slopes with shallow coarse-gravelly soils. The higher elevation in which the site occurs provides slightly more rainfall than elsewhere in the Major Land Resource Area (MLRA) and the shallow soils are favored by shallow-rooted plants which can quickly take up any available water. The result is a high-producing community dominated by shallow-rooted plants such as white brittlebush (Encelia farinosa), teddybear cholla, and ocotillo. Throughout the site there are moderate variations in the abundance of teddybear cholla as it seems especially sensitive to soil depth and/or texture. This is true to a lesser extent with ocotillo. The potential plant community is 90% shrubs, 5% forbs and 5% grasses. The total vegetation cover is 25%.
Figure 2. 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) |
|---|---|---|---|
| Shrub/Vine | 253 | 406 | 457 |
| Forb | 27 | 43 | 47 |
| Total | 280 | 449 | 504 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 15-20% |
| Grass/grasslike foliar cover | 0-2% |
| Forb foliar cover | 1-5% |
| 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. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 10-15% |
| Grass/grasslike basal cover | 0-1% |
| Forb basal cover | 0-3% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 5-10% |
| Surface fragments >0.25" and <=3" | 60-70% |
| Surface fragments >3" | 0-5% |
| Bedrock | 5-10% |
| Water | 0% |
| Bare ground | 5-10% |
Table 8. Canopy structure (% cover)
| Height Above Ground (m) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.15 | – | – | 0-2% | 1-5% |
| >0.15 <= 0.3 | – | – | – | – |
| >0.3 <= 0.6 | – | 5-10% | – | – |
| >0.6 <= 1.4 | – | 10-15% | – | – |
| >1.4 <= 4 | – | 1-5% | – | – |
| >4 <= 12 | – | – | – | – |
| >12 <= 24 | – | – | – | – |
| >24 <= 37 | – | – | – | – |
| >37 | – | – | – | – |
Additional community tables
Table 9. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 1 | Deep-rooted Shrubs | 72–130 | ||||
| creosote bush | LATR2 | Larrea tridentata | 29–52 | – | ||
| burrobush | AMDU2 | Ambrosia dumosa | 22–43 | – | ||
| white ratany | KRGR | Krameria grayi | 20–36 | – | ||
| 2 | Shallow-rooted Shrubs | 182–327 | ||||
| brittlebush | ENFA | Encelia farinosa | 81–147 | – | ||
| ocotillo | FOSP2 | Fouquieria splendens | 29–53 | – | ||
| Fremont's dalea | PSFR | Psorothamnus fremontii | 21–37 | – | ||
| Mojave woodyaster | XYTO2 | Xylorhiza tortifolia | 10–18 | – | ||
| California barrel cactus | FECY | Ferocactus cylindraceus | 7–12 | – | ||
|
Forb
|
||||||
| 3 | Forbs | 27–47 | ||||
| flatcrown buckwheat | ERDE6 | Eriogonum deflexum | 11–20 | – | ||
| desert Indianwheat | PLOV | Plantago ovata | 11–20 | – | ||
| brownplume wirelettuce | STPA4 | Stephanomeria pauciflora | 4–7 | – | ||
Interpretations
Animal community
Both desert tortoises (Gopherus agassizii) and desert tortoise burrows have been spotted in and around the site indicating that this is suitable borrowing habitat. On good rainfall years a good annual plant bloom would be expected, providing forage for tortoises as well as rodents. The site also offers a good array of vertical structure, a feature important as bird perches.
Recreational uses
This site offers excellent opportunities for photography of the natural features present. Both the teddybear cholla and ocotillo prove very charismatic subjects for pictures. Some Off-Highway Vehicle recreation is permitted on designated trails.
Other information
White brittlebush is allelopathic and produces a toxic, water soluble substance that inhibits the growth of several winter annuals. White brittlebush is also a useful plant for revetating areas. Native americans would burn the sap from white brittlebush as insence.
Supporting information
Type locality
| Location 1: San Bernardino County, CA | |
|---|---|
| UTM zone | N |
| UTM northing | 3821641 |
| UTM easting | 720987 |
| Latitude | 34° 30′ 45″ |
| Longitude | 114° 35′ 33″ |
| General legal description | This site is located in the northern Chemehuevi Wash OVH area, 5 miles east of CA HWY 95 on a major powerline road. |
Contributors
Heath M. McAllister
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 | |
| Approved by | |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
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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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