Natural Resources
Conservation Service
-
Search
Major Land Resource Area or ecological site by name and/or ID.
PreviousSectionsNextGeneral 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.
Click to explore map
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 035X–Colorado Plateau
AZ CRA 35.4 – Colorado Plateau Cold Sagebrush – Grasslands
Elevations range from 4200 to 5100 feet and precipitation averages 7 to 11 inches. Vegetation includes winterfat, fourwing saltbush, buckwheat species, needlegrass, bottlebrush squirreltail, Indian ricegrass, black grama, blue grama, sideoats grama, gyp dropseed, and galleta. The soil temperature regime is mesic and the soil moisture regime is typic aridic. This unit occurs within the Colorado Plateau Physiographic Province and is characterized by a sequence of flat to gently dipping sedimentary rocks eroded into plateaus, valleys and deep canyons. Sedimentary rock classes dominate the plateau with volcanic fields occurring for the most part near its margin.Table 1. Dominant plant species
Tree Not specified
Shrub (1) Chrysothamnus viscidiflorus
(2) Atriplex canescensHerbaceous (1) Pleuraphis jamesii
(2) Scleropogon brevifoliusPhysiographic features
The dominant aspect is cold desert shrub grassland. Major grasses are galleta and burrograss. Landform and position are lower concave positions and gentle sideslopes of drainages.
Table 2. Representative physiographic features
Landforms (1) Fan
(2) Terrace
Flooding frequency None to rare Ponding frequency None to rare Elevation 4700 – 5200 ft Slope 1 – 5 % Aspect Aspect is not a significant factor Climatic features
Winter-Summer moisture ratios are typically 70:30 on the west side of this LRU and shift to 60:40 on the east side. Late spring is usually the driest period, and early fall moisture can be sporadic. Summer rains fall June-September; moisture originates in the Gulf of Mexico and creates convective, usually brief, intense thunderstorms. Cool season moisture October-May tends to be frontal; it originates in the Pacific and the Gulf of California and falls in widespread storms with longer duration and lower intensity. Precipitation generally comes as snow December-February. Accumulations above 10 inches are not common, but can occur. Snow usually lasts 3-4 days, but can persist much longer. Summer daytime temperatures are commonly 95-100 F and, on occasion, exceed 105F. Winter air temperatures can regularly go below 15 F and have been recorded below -15 F.
Table 3 Representative climatic features
Frost-free period (average) 220 days Freeze-free period (average) 150 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
Soils on this site consist of very deep, well drained soils that formed in mixed alluvium derived dominantly from sedimentary formations and mixed gravelly alluvium and colluvium.
Soils mapped on this site include:
SSA623 Shivwits Area MU 83 Twist;
SSA625 Mohave County NE part MU's 16 & 23 Hatknoll;
SSA629 Coconino County North Kaibab part MU 19 Jocity.Table 4. Representative soil features
Parent material (1) Alluvium – basalt
Surface texture (1) Gravelly loam
(2) Loam
Family particle size (1) Loamy
Drainage class Moderately well drained to well drained Permeability class Moderately slow to slow Soil depth 40 – 60 in Surface fragment cover <=3" 5 – 20 % Surface fragment cover >3" 0 – 15 % Available water capacity
(0-40in)5 – 7.5 in Calcium carbonate equivalent
(0-40in)1 – 15 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)7.9 – 9 Subsurface fragment volume <=3"
(Depth not specified)5 – 20 % Ecological dynamics
The plant communities found on an ecological site are naturally variable. Composition and production will vary with yearly conditions, location, aspect, and the natural variability of the soils. The Historical Climax Plant Community represents the natural potential plant communities found on relict or relatively undisturbed sites. Other plant communities described here represent plant communities that are known to occur when the site is disturbed by factors such as fire, grazing, or drought.
Production data provided in this site description is standardized to air dry weight at the end of the summer growing season. The plant communities described in this site description are based on near normal rainfall years.
NRCS uses a Similarity Index to compare existing plant communities to the plant communities described here. Similarity index is determined by comparing the production and composition of a plant community to the production and composition of a plant community described in this site description. To determine Similarity index, compare the production (air dry weight) of each species to that shown in the plant community description. For each species, count no more than the maximum amount shown for the species, and for each group, count no more than the maximum amount shown for each group. Divide the resulting total by the total normal year production shown in the plant community description. If the rainfall has ben significantly above or below normal, use the total production shown for above or below normal years. If field data is not collected at the end of the summer growing season, then the field data must be corrected to the end of the year production before comparing it to the site description. The growth curve can be used as a guide for estimating production at the end of the summer growing season.
State and transition model
Custom diagramStandard diagram
More interactive model formats are also available. View Interactive Models
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
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe dominant aspect is cold desert shrub grassland. The major grasses are galleta and burrograss. With severe disturbance, native annuals, broom snakeweed, stickyleaf low rabbitbrush and wolf berry will increase; cheatgrass and russian thistle will invade.
Figure 4. 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 300 338 375 Shrub/Vine 75 113 150 Forb 5 28 50 Total 380 479 575 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 10-20% Grass/grasslike foliar cover 10-20% Forb foliar cover 0-0% 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. Canopy structure (% cover)
Height Above Ground (ft) Tree Shrub/Vine Grass/
GrasslikeForb <0.5 – – 5-15% – >0.5 <= 1 – 5-10% – 0-1% >1 <= 2 – 10-20% – – >2 <= 4.5 – – – – >4.5 <= 13 – – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 5. Plant community growth curve (percent production by month). AZ0004 , 35.4 7-11" p.z. fourwing saltbush. Some growth in spring, most growth in summer to early fall rainy season..
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 0 0 10 15 30 40 5 0 0 0 Figure 6. Plant community growth curve (percent production by month). AZ3541 , 35.4 7-11" p.z. all sites. Most growth occurs in the spring and during the summer rainy season..
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 1 9 20 15 5 16 25 6 2 1 0 Figure 7. Plant community growth curve (percent production by month). AZ3566 , 35.4 7-11" p.z. winterfat. Growth occurs from spring through summer..
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 5 30 30 10 10 10 5 0 0 0 Figure 8. Plant community growth curve (percent production by month). AZ0001 , 35.4 7-11. Growth begins in the spring, most growth occurs during the summer rainy season..
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 0 3 15 5 25 40 10 2 0 0 Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Shrub/Vine0 75–150 winterfat KRLA2 Krascheninnikovia lanata 25–50 – fourwing saltbush ATCA2 Atriplex canescens 25–50 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 25–50 – broom snakeweed GUSA2 Gutierrezia sarothrae 10–25 – water jacket LYAN Lycium andersonii 0–10 – pale desert-thorn LYPA Lycium pallidum 0–10 – Nevada jointfir EPNE Ephedra nevadensis 0–5 – 4 0–5 Whipple cholla CYWH Cylindropuntia whipplei 0–5 – globe cactus MAMMI Mammillaria 0–5 – twistspine pricklypear OPMA2 Opuntia macrorhiza 0–5 – banana yucca YUBA Yucca baccata 0–5 – Grass/Grasslike0 300–350 James' galleta PLJA Pleuraphis jamesii 75–150 – burrograss SCBR2 Scleropogon brevifolius 50–75 – squirreltail ELELE Elymus elymoides ssp. elymoides 25–50 – purple threeawn ARPU9 Aristida purpurea 15–40 – black grama BOER4 Bouteloua eriopoda 10–35 – blue grama BOGR2 Bouteloua gracilis 10–35 – sand dropseed SPCR Sporobolus cryptandrus 10–35 – needle and thread HECOC8 Hesperostipa comata ssp. comata 0–15 – Indian ricegrass ACHY Achnatherum hymenoides 0–15 – 1 0–15 black grama BOER4 Bouteloua eriopoda 7–27 – blue grama BOGR2 Bouteloua gracilis 7–27 – Grass, perennial 2GP Grass, perennial 0–5 – low woollygrass DAPU7 Dasyochloa pulchella 0–5 – ring muhly MUTO2 Muhlenbergia torreyi 0–5 – 2 34–50 squirreltail ELELE Elymus elymoides ssp. elymoides 17–34 – Grass, annual 2GA Grass, annual 0–15 – sixweeks fescue VUOC Vulpia octoflora 0–15 – Forb0 5–40 purple threeawn ARPU9 Aristida purpurea 10–27 – Forb, perennial 2FP Forb, perennial 0–10 – globemallow SPHAE Sphaeralcea 0–10 – winding mariposa lily CAFL Calochortus flexuosus 0–5 – desert trumpet ERIN4 Eriogonum inflatum 0–5 – pepperweed LEPID Lepidium 0–5 – phlox PHLOX Phlox 0–5 – 3 5–25 Forb, annual 2FA Forb, annual 5–25 – Indian ricegrass ACHY Achnatherum hymenoides 0–10 – milkvetch ASTRA Astragalus 0–5 – borage BORAG Borago 0–5 – western tansymustard DEPI Descurainia pinnata 0–5 – miniature woollystar ERDI2 Eriastrum diffusum 0–5 – desert Indianwheat PLOV Plantago ovata 0–5 – Interpretations
Animal community
This site is suitable for yearlong grazing by either cows and calves or stocker cattle and is easily traversed by all classes of livestock. Prescribed Grazing systems adapt very well to use on this site.
Potential wildlife on site are pronghorn antelope, black-tailed jackrabbit, coyote, badger, antelope squirrel, kangaroo rat, deer mouse, red tail hawk, raven meadowlark, gopher snake, western rattlesnake, longnose leopard lizard, short-horned lizard, western whiptail, and black-collared lizard.Recreational uses
This site is found gently sloping valley sides, characterized by open grasslands interspersed with a few flowering forbs and shrubs.
Winters are cold and summers are quite warm. Spring and fall are the dry seasons and are typically cool and windy.
Recreational activities most likely to occur are hunting, cross-country riding, photography and wildlife observation.
Other information
Threatened and Endangered Species: Golden eagles and Prairie falcons occasionally use the site for feeding areas.
Supporting information
Type locality
Location 1: Mohave County, AZ Township/Range/Section T38N R7W S35 General legal description Little Clayhole Valley 7 1/2 min. quad; 1 mi east of Black Point Reservoir Contributors
ASM, SEC
Larry D. Ellicott
Steve BarkerRangeland 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
-
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:
Print Options
Sections
Font
AAAAOther
PrintThe Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
Accessibility statement
