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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 35.4 – 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) Atriplex canescens
(2) Mahonia trifoliolataHerbaceous (1) Achnatherum hymenoides
(2) Hesperostipa comataPhysiographic features
This range site occurs in an upland position and does not benefit from run-in moisture. It often suffers from excess runoff bacause of soil conditions and slope. It typically occurs as broken or undulating sandstone mesas and plateaus, particularly near washes and breaks.
Table 2. Representative physiographic features
Landforms (1) Mesa
(2) Plateau
(3) Fan
Flooding frequency None to rare Ponding frequency None to rare Elevation 3800 – 5300 ft Slope 1 – 30 % 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 are shallow to moderately deep to any plant-root restricting bedrock. Moderately deep phases are skeletal. These soils occur on highly fractured sandstone and shale. The surface consists of layered broken fragments interspersed with sandy loam to loam pockets. The layered nature of these coarse fragments greatly contributes to runoff. Available water capacity is low. The subsurface consists of skeletal loams. pH range is 7.4-8.6.
Soil taxonomic unit on this site:
SSA629 Coconino County North Kaibab part MU 11 Curob.Table 4. Representative soil features
Parent material (1) Alluvium – limestone
Surface texture (1) Sandy loam
(2) Loam
Family particle size (1) Loamy
Drainage class Well drained to somewhat excessively drained Permeability class Moderately slow to moderate Soil depth 5 – 20 in Surface fragment cover <=3" 0 – 35 % Available water capacity
(0-40in)2.5 – 5 in Calcium carbonate equivalent
(0-40in)15 – 40 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)7.4 – 8.6 Subsurface fragment volume <=3"
(Depth not specified)30 – 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 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
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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 vegetation is a complex of grasses, forbs and shrubs. Ground cover is relatively sparse. Both cool and warm season plants are important.
Plants most likely to increase through overgrazing are snakeweed, goldenweed, big sagebrush and algerita. Invading species are russian thistle and cheatgrass.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 252 294 336 Shrub/Vine 252 280 308 Forb 6 17 28 Total 510 591 672 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). AZ0005 , 35.4 7-11" p.z. Indian ricegrass. Most growth occurs in the spring, some growth occurs in the fall..
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 10 40 40 0 0 0 5 5 0 0 Figure 7. 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 8. Plant community growth curve (percent production by month). AZ3542 , 35.4 7-11" p.z. Needle and thread. Growth occurs mostly in the spring..
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 15 60 20 5 0 0 0 0 0 0 Figure 9. Plant community growth curve (percent production by month). AZ5215 , 35.4 7-11" p.z. black grama. Growth occurs mostly 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 0 5 5 30 50 10 0 0 0 Figure 10. 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 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Shrub/Vine0 170–225 fourwing saltbush ATCA2 Atriplex canescens 85–110 – jointfir EPHED Ephedra 80–105 – algerita MATR3 Mahonia trifoliolata 15–30 – 3 0–6 threeawn ARIST Aristida 3–9 – big sagebrush ARTR2 Artemisia tridentata 0–6 – Mexican cliffrose PUME Purshia mexicana 0–6 – 4 45–120 fourwing saltbush ATCA2 Atriplex canescens 84–112 – Bigelow sage ARBI3 Artemisia bigelovii 8–35 – bastardsage ERWR Eriogonum wrightii 5–30 – broom snakeweed GUSA2 Gutierrezia sarothrae 14–28 – slender goldenweed MAGR10 Machaeranthera gracilis 14–28 – plains pricklypear OPPO Opuntia polyacantha 6–17 – Grass/Grasslike0 20–80 spike dropseed SPCO4 Sporobolus contractus 15–30 – wildrye ELYMU Elymus 0–28 – threeawn ARIST Aristida 6–17 – squirreltail ELELE Elymus elymoides ssp. elymoides 3–15 – 1 110–165 Indian ricegrass ACHY Achnatherum hymenoides 59–88 – desert needlegrass ACSP12 Achnatherum speciosum 59–88 – needle and thread HECOC8 Hesperostipa comata ssp. comata 59–88 – 2 90–150 sideoats grama BOCU Bouteloua curtipendula 44–74 – black grama BOER4 Bouteloua eriopoda 44–74 – blue grama BOGR2 Bouteloua gracilis 44–74 – bush muhly MUPO2 Muhlenbergia porteri 44–74 – James' galleta PLJA Pleuraphis jamesii 15–29 – spike dropseed SPCO4 Sporobolus contractus 15–29 – James' galleta PLJA Pleuraphis jamesii 13–26 – Forb0 6–28 Forb, annual 2FA Forb, annual 6–28 – Forb, perennial 2FP Forb, perennial 6–28 – wildrye ELYMU Elymus 0–15 – Interpretations
Animal community
This range site is relatively low in productivity. Rocky soils make mechanical range improvement practices impractical. This site may provide shelter for livestock in cold winter weather.
The site has fair to good diversity, but poor plant cover and productivity for wildlife. Permanent open waters are lacking. Breaks and crevices provide additional cover for some species such as the mule deer.Recreational uses
The site ocnsists of broken and undulating sandstone mesas and plateaus. It has a relatively sparse complex of shrubs and grasses, with interspaces of fractured layers of exposed sandstone. Winters are cold and summers are warm. Spring and fall are typically dry, cool and windy. Hunting, cross country riding and wildlife observation are the occasional recreational activities on the site.
Other products
Sandstone slabs are occasionally quarried on this site.
Other information
Threatened and Endangered Species: Golden eagles and Prairie falcons occasionally use the site for feeding areas.
Supporting information
Type locality
Location 1: Coconino County, AZ Township/Range/Section T37N R4E S15 General legal description In Coconino County; 19 miles southwest of Marble Canyon; Section 15, T37N, R4E. Contributors
Larry D. Ellicott
Steve Barker
UnknownRangeland 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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