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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Associated sites
R029XY183CA Shallow Granitic Slope 7-9" p.z.
R029XY183CA Shallow Granitic Slope 7-9" p.z. occurs on adjacent mountains, hills, and fan remnants. The major species is blackbrush (Coleogyne ramosissima).
R029XY185CA Shallow Granitic Hills 7-9" p.z.
R029XY185CA Shallow Granitic Hills 7-9" p.z. occurs on adjacent hills. Blackbrush (Coleogyne ramosissima), California buckwheat (Eriogonum fasciculatum), and Sandberg bluegrass (Poa secunda) are major species.
Table 1. Dominant plant species
Tree (1) Yucca brevifolia
Shrub (1) Hymenoclea salsola
Herbaceous (1) Achnatherum speciosum
Physiographic features
This ecological site occurs on fan aprons. Water from adjacent, higher elevation areas drains into this ecosite and creates mild disturbances. Major flood events occur every 20 to 50 years (Harris 2006).
Table 2. Representative physiographic features
Landforms (1) Fan apron
Flooding duration Extremely brief (0.1 to 4 hours) Flooding frequency Rare Ponding frequency None Elevation 3800 – 4800 ft Slope 4 – 15 % Aspect Aspect is not a significant factor Climatic features
The Mojave Desert experiences clear, dry conditions for a majority of the year. Winter temperatures are mild, summer temperatures are hot, and seasonal and diurnal temperature fluctuations are large. Monthly minimum temperature averages range from 30 to 80 degrees F (-1 to 27 degrees C). Monthly maximum temperature averages range from 60 to 110 degrees F (16 to 43 degrees C) (CSU 2002).
Average annual rainfall is between 2 and 8 inches (50 to 205 millimeters) (USDA 2006). Snowfall is more common at elevations above 4000 feet (1220 meters), but it may not occur every year (WRCC 2002). The Mojave Desert receives precipitation from two sources. Precipitation falls primarily in the winter as a result of storms originating in the northern Pacific Ocean. The Sierra Nevada and Transverse Ranges create a rain shadow effect, causing little precipitation to reach the Mojave Desert. Sporadic rainfall occurs during the summer as a result of convection storms formed when moisture from the Gulf of Mexico or Gulf of California moves into the region. Summer rainfall is more common and has a greater influence on soil moisture in the eastern Mojave Desert.
Windy conditions are also common in the Mojave Desert, particularly in the west and central Mojave Desert. Spring is typically the windiest season, with winds averaging 10-15 miles per hour (WRCC 2002). Winds in excess of 25 miles per hour and gusts in excess of 50 miles per hour are not uncommon (CSU 2002).
Although half of the Jawbone-Butterbredt ACEC Soil Survey is in the Mojave Desert (MLRA 30), the western and northwestern areas of the survey transition into the Southern Nevada Basin and Range (MLRA 29). As the Mojave Desert transitions into the Southern Nevada Basin and Range, the temperature range generally becomes cooler (WRCC 2002). Precipitation as rain and as snow also increases (USDA 2006). This survey area has a wide range of precipitation due to its location. Where the Mojave Desert influences are stronger, average annual precipitation ranges from 5 to 7 inches (127 to 178 millimeters). Where the Southern Nevada Basin and Range influences are stronger, average annual precipitation commonly ranges from 7 to 9 inches (178 to 229 millimeters), and may range up to 12 inches (305 millimeters) annually (WRCC 2002). At elevations above 4000 feet (1370 meters), average annual snowfall may reach 20 inches (WRCC 2002).
The data from the following climate stations were used to describe the climate in the Jawbone-Butterbredt ACEC Soil Survey (station number in parentheses):
Cantil, CA (041488)
Inyokern, CA (044278)
Mojave, CA (045756)
Tehachapi, CA (048826)
"Maximum monthly precipitation" represents average monthly precipitation.
Table 3 Representative climatic features
Frost-free period (average) 220 days Freeze-free period (average) 0 days Precipitation total (average) 10 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
The soils on this ecological site are derived from granitic alluvium. Soils are very deep (>60 inches), sandy, and somewhat excessively drained. Permeability is rapid to very rapid, and runoff is low. Because of its low position on the landscape, water drains toward this ecosite. This causes subtle disturbances such as sheet erosion, or it may cause major flood events. Larger amounts of material may be removed or deposited during major flood events. Constant alluvial activity does not allow soils to develop diagnostic characteristics, and therefore soils are classified as mixed, thermic Typic Torripsamments. Available water capacity is very low to low.
Soil survey area - Map unit symbol - Component
CA682 – 5500 – Birdcanyon (major)
CA682 – 6003 – Birdcanyon
Table 4. Representative soil features
Surface texture (1) Coarse sand
Family particle size (1) Sandy
Drainage class Somewhat excessively drained Permeability class Rapid to very rapid Soil depth 60 – 0 in Surface fragment cover <=3" 40 – 65 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)2.4 – 4.8 in Calcium carbonate equivalent
(0-40in)0 – 1 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)6.6 – 7.8 Subsurface fragment volume <=3"
(Depth not specified)5 – 10 % Subsurface fragment volume >3"
(Depth not specified)Not specified Ecological dynamics
This ecological site occurs on fan aprons. The major species on this ecosite are burrobrush (Hymenoclea salsola) and Joshua tree (Yucca brevifolia). These species are commonly found where moisture is higher (Hickman 1993, Somerville [no date]). Due to its location in the landscape, this ecosite is affected by relatively regular alluvial activites and mild disturbances. Runoff and debris from adjacent, higher elevation areas are inputs to this site, while sheet flow and more intense flooding removes materials from this site. More intense flooding occurs every 20 to 50 years, with the last major flood occurring in 1984 (Harris 2006).
This ecosite is also affected by fire, but not frequently. Wildfire has historically been uncommon in the desert because widely spaced shrubs and discontinuous fuels prevented fires from spreading easily. The last burn on the site occurred about 50-75 years ago (Harris 2006). Both burrobrush and Joshua tree are able to regenerate easily following a fire. Joshua tree will sprout from its base provided the disturbance was not sufficiently intense to destroy its underground tissues. burrobrush is also readily adapted to colonize a site after disturbance. Grasses also become more abundant following disturbances, and are maintained by future natural disturbances or anthropogenic uses.
Regular disturbances keep early seral species in the community. The interval between large disturbances may enable later seral species to establish. This interval may be enough for these plants to accumulate woody tissue and develop a root system that will allow it to survive larger disturbances.
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
Burrobrush - Joshua TreeCommunity 1.1
Burrobrush - Joshua TreeThe reference plant community for this ecological site is that which presently exists on the site. The pre-European settlement reference community for this ecological site is difficult to identify due to the history of disturbance, particularly by fire, as well as current anthropogenic disturbances such as grazing. Burrobrush and other early seral species would have probably been present in the pre-European settlement reference community due to the regular disturbances created by water. Other late seral species may have been more common but for major disturbances that removed many individuals and subsequent anthropogenic uses that have prevented those species from re-establishing to past levels.
This community is dominated by burrobrush and Joshua tree. Mid- and late-seral species such as blackbrush (Coleogyne ramosissima), white bursage (Ambrosia dumosa), Cooper’s wolfberry (Lycium cooperi), and longspine horsebrush (Tetradymia axillaris) are also present in this community. The dominance of burrobrush on this ecosite suggests both recent or regular disturbance events. Burrobrush is common in areas disturbed by water, but it is also a short-lived species. Persistence of this species on this site over time would require a regular occurrence of disturbance. Infrequent disturbances would likely increase the dominance of some mid- and late-seral species over burrobrush due to their longer lifespan.
Nearly uniform heights of Joshua trees across large areas indicates a widespread disturbance by fire (Harris 2006). More variability in height would have been expected if the disturbance was small scale or less intense.
Native vegetation covers approximately 50% of the ground, and it has a multi-tiered structure. Joshua trees are the tallest species, and grasses are frequently found under shrubs in this community. Percent cover by species may sum to greater than 100% as a result of this multi-tiered structure. Non-native vegetation contributes less than 5% of the vegetation cover of this ecosite, and is predominantly red brome (Bromus rubens).
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)Shrub/Vine 264 396 528 Grass/Grasslike 108 162 216 Forb 28 42 56 Total 400 600 800 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 30-30% Grass/grasslike foliar cover 0-10% Forb foliar cover 0-10% 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 10-20% Grass/grasslike basal cover 0-0% Forb basal cover 0-0% Non-vascular plants 0% Biological crusts 0% Litter 10-20% Surface fragments >0.25" and <=3" 0-0% Surface fragments >3" 0% Bedrock 0% Water 0% Bare ground 0% Table 8. Canopy structure (% cover)
Height Above Ground (ft) Tree Shrub/Vine Grass/
GrasslikeForb <0.5 – – – 3-5% >0.5 <= 1 – – – – >1 <= 2 – 5-10% 2-3% – >2 <= 4.5 – 5-10% – – >4.5 <= 13 – 5-10% – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Additional community tables
Table 9. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Shrub/Vine1 Shrubs 264–528 burrobrush HYSA Hymenoclea salsola 140–280 – Joshua tree YUBR Yucca brevifolia 100–200 – Nevada jointfir EPNE Ephedra nevadensis 12–24 – Acton's brittlebush ENAC Encelia actonii 8–16 – buck-horn cholla CYAC8 Cylindropuntia acanthocarpa 4–8 – Grass/Grasslike2 Perennial grasses 108–216 desert needlegrass ACSP12 Achnatherum speciosum 76–138 – Sandberg bluegrass POSE Poa secunda 32–78 – Forb3 Annual forbs 16–32 bristly fiddleneck AMTE3 Amsinckia tessellata 12–24 – blazingstar MENTZ Mentzelia 4–8 – 4 Perennial forbs 12–24 Interpretations
Animal community
This ecological site is used as grazing land for domestic livestock. The large amount of grasses on this site and the gentle terrain make it a valuable, regularly used grazing land (Harris 2006). Controlled grazing helps promote production of perennial grasses.
Joshua trees important shelter for several wildlife species, particularly birds and lizards. Birds and small mammals also use Joshua tree fruit and flowers as a food source. Leaves are used in the nests of small mammals.
Hydrological functions
This ecological site is frequently affected by mild water disturbance. Water enters the site from adjacent, higher elevation areas. Water may bring debris onto the site and may cause sheetwashing as it leaves the site. Major flooding occurs on an interval of approximately 20 to 50 years.
Recreational uses
This ecological site is located in an off-highway vehicle recreation area. Established riding trails are present near this ecosite.
Supporting information
Inventory data references
3 NV-ECS-1 Range Inventory Worksheet 3 Line point intercept transects 1 SCS Range 417 Production and Composition Record
Type locality
Location 1: Kern County, CA UTM zone N UTM northing 3933162 UTM easting 400401 Latitude 35° 28′ 28″ Longitude 118° 5′ 55″ General legal description Annual biomass production was sampled at this location. It is located off SC120, approximately 2 miles east of the Pacific Crest Trail. Other references
California State University (CSU) Desert Studies Center. 2002. Desert Climate. CSU Desert Studies Center, Soda Springs, CA. Online. http://biology.fullerton.edu/facilities/dsc/zz_climate.html. Accessed 28 November 2006.
Harris, Glenn. Personal communication. Natural Resources Specialist, Bureau of Land Management, Ridgecrest, CA. November 8, 2006.
Hickman, James C. (Ed.). 1993. The Jepson manual: higher plants of California. University of California Press, Berkeley, CA. 1400 pp.
Somerville, Graeme. [no date]. The biogeography of the Joshua tree (Yucca brevifolia). Adapted from http://bss.sfsu.edu/geog/bholzman/courses/fall99projects/yucca.htm. Available online: http://hegel.lewiscenter.org/users/mhuffine/projects/sci_pdf/josh_tree_bio%5B1%5D.prn.pdf. Accessed 23 April 2007.
United States Department of Agriculture (USDA), Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.
Western Regional Climate Center (WRCC). 2002. Western U.S. Climate Historical Summaries [Online]. Desert Research Institute, Reno, NV. Online. http://www.wrcc.dri.edu/Climsum.html. Accessed 28 November 2006.
Contributors
Allison Tokunaga
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:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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