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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.
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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 35.3 – Colorado Plateau Sagebrush – Grasslands
Elevations range from 4500 to 6000 feet and precipitation averages 10 to 14 inches. Vegetation includes Wyoming big sagebrush, Utah juniper, Colorado pinyon - cliffrose, Mormon tea, fourwing saltbush, blackbrush Indian ricegrass, needle and thread, western wheatgrass Galleta, black grama, blue grama, and sand dropseed. The soil temperature regime is mesic and the soil moisture regime is ustic 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 (1) Juniperus osteosperma
Shrub (1) Coleogyne ramosissima
Herbaceous (1) Bouteloua curtipendula
(2) Elymus elymoides ssp. elymoidesPhysiographic features
These sites are on basalt flows and mesas.
Table 2. Representative physiographic features
Landforms (1) Mesa
Flooding duration Extremely brief (0.1 to 4 hours) to very brief (4 to 48 hours) Flooding frequency None to rare Ponding frequency None Elevation 4800 – 5800 ft Slope 2 – 35 % Aspect Aspect is not a significant factor Climatic features
Winter summer moisture ratios range from 70:30 to 60:40. Late spring is usually the driest period, and early fall moisture can be sporadic. Summer rains fall from June through September; moisture originates in the Gulf of Mexico and creates convective, usually brief, intense thunderstorms. Cool season moisture from October through 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 from December through February. Accumulations above 12 inches are not common but can occur. Snow usually lasts for 3-4 days, but can persist much longer. Summer daytime temperatures are commonly 95 - 100 F and on occasion exceed 105 F. Winter air temperatures can regularly go below 10 F and have been recorded below - 20 F.
Table 3 Representative climatic features
Frost-free period (average) 170 days Freeze-free period (average) 190 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
The soils on this site consist of shallow, well drained, slowly permeable soils that formed in eolian material and alluvium weathered from basalt.
Typical taxonomic unit includes:
SSA 697 Mohave County Central Part MU 114 prieta;
SSA 699 Hualapai-Havasupai Area MU 36 prieta.Table 4. Representative soil features
Parent material (1) Eolian deposits – basalt
Surface texture (1) Extremely cobbly loam
(2) Very cobbly loam
Family particle size (1) Loamy
Drainage class Moderately well drained to well drained Permeability class Moderately slow to slow Soil depth 5 – 20 in Surface fragment cover >3" 20 – 40 % Available water capacity
(0-40in)0 – 2.5 in Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)6.8 – 7.6 Subsurface fragment volume <=3"
(Depth not specified)0 – 10 % Subsurface fragment volume >3"
(Depth not specified)20 – 40 % 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 grazing, fire, 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 shown for the group. Divide the resulting total by the total normal year production shown in the plant community description. If rainfall has been 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
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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 CommunityThis site consists of a plant community of grasses with a significant percentage of shrubs. In the potential plant community, there is a mixture of cool and warm season grasses.
Plant species most likely to increase or invade on this site when it deteriorates are fendler threeawn, broom snakeweed, Buckhorn cholla, and annual grasses and forbs. Continuous livestock grazing during the spring will decrease cool season grasses, which are replaced by lower forage grasses and shrubs.
Because of the scattered canopy cover and sparse understory, this site does not have a history of regular fire disturbance. Blackbrush plant communities are often quite old and tend to be stable. If it is severely disturbed this site will revert to an early seral stage of mostly annuals, including a large increase of cheatgrass brome and broom snakeweed. A more advanced plant community will contain scattered desert shrubs and a small increase in perennial grasses, with little regeneration of blackbrush. It is speculated that blackbrush communities evolved under a different climatic regime, and once removed will not readily return to a site.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)Shrub/Vine 206 248 303 Grass/Grasslike 159 191 234 Forb 11 14 17 Tree 11 14 17 Total 387 467 571 Table 6. Ground cover
Tree foliar cover 0-10% Shrub/vine/liana foliar cover 10-30% Grass/grasslike foliar cover 0-10% 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 – 0-5% 1-2% 0-1% >0.5 <= 1 – 1-2% – – >1 <= 2 – 1-10% 0-5% – >2 <= 4.5 – 5-25% – – >4.5 <= 13 0-5% – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 5. Plant community growth curve (percent production by month). AZ3504 , 35.3 10-14" p.z. bottlebrush squirreltail. Growth occurs in late winter, spring, and fall. Plants often remain green through the winter..
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 5 15 35 25 10 0 0 5 5 0 0 Figure 6. Plant community growth curve (percent production by month). AZ3514 , 35.3 10-14" p.z. muttongrass. Growth begins in spring and continues with the summer rains..
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 15 20 20 20 10 10 0 0 0 Figure 7. Plant community growth curve (percent production by month). AZ3531 , 35.3 10-14" p.z. all sites. Growth begins in the spring and continues through the 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 1 3 17 18 10 19 20 10 1 1 0 Figure 8. Plant community growth curve (percent production by month). AZ5103 , 35.1 10-14" p.z. sideoats grama. Most growth occurs in summer and early fall during the 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 5 10 20 30 20 10 5 0 0 Figure 9. Plant community growth curve (percent production by month). AZ5105 , Blackbrush. Cool season grower, shuts down quickly when it gets hot..
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 5 20 50 20 5 0 0 0 0 0 0 Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Tree0 Orig Range Site 5–23 Utah juniper JUOS Juniperus osteosperma 5–23 – singleleaf pinyon PIMO Pinus monophylla 0–14 – Shrub/Vine0 Orig Range Site 225–270 blackbrush CORA Coleogyne ramosissima 180–203 – Shrub (>.5m) 2SHRUB Shrub (>.5m) 5–23 – Stansbury cliffrose PUST Purshia stansburiana 5–23 – Utah agave AGUT Agave utahensis 0–14 – mormon tea EPVI Ephedra viridis 5–14 – bastardsage ERWR Eriogonum wrightii 0–9 – fourwing saltbush ATCA2 Atriplex canescens 0–9 – banana yucca YUBA Yucca baccata 0–9 – beavertail pricklypear OPBA2 Opuntia basilaris 0–5 – Grass/Grasslike0 Orig Range Site 180–203 sideoats grama BOCU Bouteloua curtipendula 45–68 – squirreltail ELELE Elymus elymoides ssp. elymoides 23–45 – muttongrass POFE Poa fendleriana 23–45 – Grass, perennial 2GP Grass, perennial 5–23 – Indian ricegrass ACHY Achnatherum hymenoides 0–23 – desert needlegrass ACSP12 Achnatherum speciosum 0–14 – Fendler's threeawn ARPUF Aristida purpurea var. fendleriana 0–9 – black grama BOER4 Bouteloua eriopoda 0–9 – blue grama BOGR2 Bouteloua gracilis 0–9 – needle and thread HECOC8 Hesperostipa comata ssp. comata 0–9 – big galleta PLRI3 Pleuraphis rigida 0–9 – slim tridens TRMU Tridens muticus 0–5 – Forb0 Orig Range Site 5–23 Forb, perennial 2FP Forb, perennial 5–14 – Forb, annual 2FA Forb, annual 5–9 – desert globemallow SPAM2 Sphaeralcea ambigua 0–5 – Interpretations
Animal community
This site is suitable for grazing during any period of the year by cows and calves, stocker cattle, sheep and horses. Prescribed grazing systems can benefit this site by allowing rest periods for the cool season species.
The potential plant community provides a variety of food and cover plants for wildlife. There is relatively poor diversity within the plant community of this site. Because of the shrub component, the site is dominated by shrubland wildlife species. However, the site is transitory to almost all species because of the lack of water. Grazing practices that encourage cool season grass species are beneficial to antelope, cottontails and rodents. Shrubs that provide both food and cover should be maintained.
Recreational uses
Site is located on gently sloping plains and mesa tops which lend themselves to activities such as horseback riding, photography, and wildlife observation. This site has a variety of spring and summer flowers.
Winters are cold, however, relatively mild spring, fall and summer months are attractive to recreationists.
Supporting information
Type locality
Location 1: Mohave County, AZ Township/Range/Section T29N R15W S21 General legal description Grapevine Canyon Quad; Southeast corner of Quad along Buck and Doe Road; Section 21, T29N, R15W; Hualapai Indian Reservation. Contributors
Karlynn Huling
Larry D. EllicottRangeland 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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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.
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