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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 4800 to 6700 feet and precipitation averages 10 to 14 inches. The elevation range is lower (about 4500 to 6000 ) on the western edge of the Colorado Plateau along the Grand Canyon, and moves up about 500 to 800 feet higher on the eastern side in the areas of the Navajo and Hopi Indian Reservations due to rain shadow effects from the Kaibab Plateau and Mogollon Rim. 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) Pleuraphis jamesii
(2) Achnatherum speciosumPhysiographic features
This site is located in an upland position. It neither benefits from run-in, nor does it suffer from excessive runoff unless fire, drought or other disturbances remove the vegetative cover. Landform and position is on hills, plateaus, mesas and remnants of mesas and ridges.
Table 2. Representative physiographic features
Landforms (1) Hill
(2) Plateau
(3) Mesa
Flooding duration Extremely brief (0.1 to 4 hours) to very brief (4 to 48 hours) Flooding frequency None to rare Ponding duration Very brief (4 to 48 hours) to brief (2 to 7 days) Ponding frequency None to rare Elevation 4800 – 6700 ft Slope 1 – 30 % 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 moisture on this ecological site is from precipitation. This ecological site does not benefit significantly from run-in, nor does it suffer from excessive runoff unless fire, drought or other disturbances remove the vegetative cover. The shallow bedrock may concentrate moistue in the deeper soil pockets, increasing plant productivity in those areas.
Soil features
Soils are very shallow to shallow (<20") over limestone and sandstone bedrock. Surface textures are very gravelly fine sandy loam to gravelly loam. Subsoil texture is very gravelly loam. Parent material is mixed alluvium, colluvium and eolian deposits from sedimentary formations, including limestone and sandstone. Available water capacity is very low. Water erosion potential is moderate to severe; wind erosion potential is very slight to slight. Soils are non-saline, non-sodic with a pH range of 7.4-8.4. Soil moisture regime is ustic aridic; soil temperature regime is mesic.
Soil Survey map unit components correlated to this ecological site include:
Shivwits Area (AZ623) Soil map unit components 18-Childers, 47-Mellenthin, 50-Mellenthin, 60-Childers, Pocum & Ubank, 76-Tassi;
Mohave County NE part (AZ625) Soil map unit components 36-Mellenthin;
Grand Canyon Area (AZ701) Soil map unit components 15-Calcic petrocalcids, 28-Meriwhitica;
Navajo Mountain Area (AZ711) Soil map unit components 25-Westmion, 38-Pocum family.Table 4. Representative soil features
Parent material (1) Alluvium – limestone and sandstone
Surface texture (1) Very gravelly fine sandy loam
(2) Gravelly loam
(3) Very gravelly loam
Family particle size (1) Loamy
Drainage class Well drained to somewhat excessively drained Permeability class Moderate Soil depth 5 – 20 in Surface fragment cover <=3" 0 – 15 % Surface fragment cover >3" 15 – 40 % Available water capacity
(0-40in)0 – 2.5 in Calcium carbonate equivalent
(0-40in)0 – 30 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)7.4 – 8.4 Subsurface fragment volume <=3"
(Depth not specified)0 – 25 % Subsurface fragment volume >3"
(Depth not specified)0 – 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.
The State and Transition diagram below reflects the current understanding of ecological dynamics for the site and describes the most commonly occurring plant communities found on the site. This diagram may not contain all the possible states, transitions and plant communities at this time. However, as more data is collected, additional information can be incorporated to modify the diagram to describe previously unknown plant communities, states and pathways.State and transition model
Custom diagramStandard diagram
Figure 4. 35-3 Shallow Loamy Warm S&T
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 2 submodel, plant communities
State 1
Reference StateCommunity 1.1
Historic Climax Plant CommunityThe dominant aspect of this site is a desert shrub. The site is dominated by blackbrush, with minor amounts of perennial grasses. At higher elevations, the percent composition of grass increases, making up to 40-50% composition of the plant community. Disturbance may increase the amount of annual and perennial grasses and forbs. If burned, or killed in some other manner, blackbrush is very slow to reestablish in the plant community.
Figure 5. 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 300 340 385 Grass/Grasslike 75 85 100 Forb 10 15 20 Tree 1 2 4 Total 386 442 509 Table 6. Ground cover
Tree foliar cover 0-0% 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 – – – 0-1% >0.5 <= 1 – – 0-5% – >1 <= 2 – 5-10% – – >2 <= 4.5 – 10-20% – – >4.5 <= 13 0-1% – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 6. Plant community growth curve (percent production by month). AZ3503 , 35.3 10-14" p.z. galleta. Growth begins in spring, most growth occurs during summer and early fall rainy season. Plants will green up again 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 0 0 5 20 15 20 30 10 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). AZ3532 , Desert needlegrass. Makes most growth from April to May.
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 50 30 0 0 0 0 0 0 0 Figure 9. Plant community growth curve (percent production by month). AZ3533 , Nevada mormon tea. Grows mainly in spring and early 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 25 25 20 15 10 0 0 0 0 Figure 10. 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 State 2
Native / Introduced StateCommunity 2.1
Shrubland - Native Grasses with Introduced AnnualsThis community phase is very similar to 1.1, except with minor amounts of introduced non-native annuals, such as Russian thistle, filaree, and cheatgrass.
Transition T1A
State 1 to 2Introduction of non-native annual grasses and forbs such as cheatgrass and Russian thisle that affect the biotic integrity and hydrology of the site.
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Dominant Grasses 75–140 James' galleta PLJA Pleuraphis jamesii 20–50 – desert needlegrass ACSP12 Achnatherum speciosum 15–30 – blue grama BOGR2 Bouteloua gracilis 10–20 – squirreltail ELELE Elymus elymoides ssp. elymoides 5–15 – prairie Junegrass KOMA Koeleria macrantha 5–15 – sand dropseed SPCR Sporobolus cryptandrus 5–15 – Indian ricegrass ACHY Achnatherum hymenoides 5–15 – 2 Other Perennial Grasses 5–20 Grass, perennial 2GP Grass, perennial 0–10 – Mormon needlegrass ACAR14 Achnatherum aridum 0–5 – Indian ricegrass ACHY Achnatherum hymenoides 0–5 – threeawn ARIST Aristida 0–5 – sideoats grama BOCU Bouteloua curtipendula 0–5 – black grama BOER4 Bouteloua eriopoda 0–5 – low woollygrass DAPU7 Dasyochloa pulchella 0–5 – needle and thread HECOC8 Hesperostipa comata ssp. comata 0–5 – common wolfstail LYPH Lycurus phleoides 0–4 – burrograss SCBR2 Scleropogon brevifolius 0–4 – slim tridens TRMU Tridens muticus 0–4 – slim tridens TRMUE Tridens muticus var. elongatus 0–4 – sand dropseed SPCR Sporobolus cryptandrus 1–2 – 3 Annual Grasses 10–25 Grass, annual 2GA Grass, annual 9–21 – red brome BRRU2 Bromus rubens 0–9 – cheatgrass BRTE Bromus tectorum 0–9 – sixweeks fescue VUOC Vulpia octoflora 0–9 – Forb4 Dominant Perennial Forbs 10–20 globemallow SPHAE Sphaeralcea 10–20 – prairie Junegrass KOMA Koeleria macrantha 0–4 – 5 Annual Forbs 0–15 Forb, annual 2FA Forb, annual 0–10 – mustard BRASS2 Brassica 0–10 – James' galleta PLJA Pleuraphis jamesii 4–9 – 6 Perennial Forbs 0–15 Forb, perennial 2FP Forb, perennial 0–5 – winding mariposa lily CAFL Calochortus flexuosus 0–5 – bluedicks DICAC5 Dichelostemma capitatum ssp. capitatum 0–5 – gilia GILIA Gilia 0–5 – Colorado four o'clock MIMU Mirabilis multiflora 0–5 – phlox PHLOX Phlox 0–5 – blue grama BOGR2 Bouteloua gracilis 2–4 – Shrub/Vine7 Dominant Shrubs 200–350 blackbrush CORA Coleogyne ramosissima 200–275 – Nevada jointfir EPNE Ephedra nevadensis 10–25 – mormon tea EPVI Ephedra viridis 10–25 – banana yucca YUBA Yucca baccata 10–25 – Mexican cliffrose PUME Purshia mexicana 5–15 – Wyoming big sagebrush ARTRW8 Artemisia tridentata ssp. wyomingensis 5–15 – fourwing saltbush ATCA2 Atriplex canescens 5–15 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 5–10 – Apache plume FAPA Fallugia paradoxa 5–10 – broom snakeweed GUSA2 Gutierrezia sarothrae 5–10 – 8 Succulent Shrubs 5–20 blackbrush CORA Coleogyne ramosissima 145–210 – echinocactus ECHIN2 Echinocactus 0–5 – kingcup cactus ECTR Echinocereus triglochidiatus 0–5 – globe cactus MAMMI Mammillaria 0–5 – plains pricklypear OPPO Opuntia polyacantha 0–5 – grizzlybear pricklypear OPPOH Opuntia polyacantha var. hystricina 0–5 – pricklypear OPUNT Opuntia 0–5 – 9 Other shrubs 5–15 Shrub (>.5m) 2SHRUB Shrub (>.5m) 0–5 – Torrey's jointfir EPTO Ephedra torreyana 0–5 – Eastern Mojave buckwheat ERFAP Eriogonum fasciculatum var. polifolium 0–5 – spiny hopsage GRSP Grayia spinosa 0–5 – water jacket LYAN Lycium andersonii 0–5 – pale desert-thorn LYPA Lycium pallidum 0–5 – Fremont's mahonia MAFR3 Mahonia fremontii 0–5 – Tree10 Trees 0–4 Utah juniper JUOS Juniperus osteosperma 0–4 – Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
This site is suitable for yearlong grazing by either cows and calves or stocker cattle but is not easily traversed by livestock because of the steep slopes and rough surface of cobbles and stones. Prescribed grazing systems can benefit this site by allowing rest periods for the cool season species.
This site offers a fair diversity in the vegetative complex for wildlife. In higher condition classes the site is most suitable to grassland wildlife species. As retrogression occurs the woody species increase and wildlife species utilizing the site may change.
Wildlife sometimes present are Mule deer, black-tailed jackrabbit, coyote, western rattlesnake, gopher snake, and antelope squirrel.
Recreational uses
Site is typically on hills, plateaus, mesas and ridges. It has rough surfaces which limit vehicles and animals.
Winters are cold, however, relatively mild spring, fall and summer months are attractive to recreationists.
Activities include hunting, photography, hiking, rock collecting, and wildlife observation.
Supporting information
Type locality
Location 1: Mohave County, AZ Township/Range/Section T41N R10W S26 General legal description Rock Canyon Quad; About 1 mile south of Cottonwood Canyon and 1/2 mile east of the Hurricane Cliffs; Section 26, T41N, R10W; Mohave County, AZ Contributors
Dan Carroll
Larry D. Ellicott
SEC/ASM
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) Dan Carroll Contact for lead author Date 10/29/2010 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None would be expected until steeper slopes in conjunction with bare soil are encountered. -
Presence of water flow patterns:
Water flow patterns are evident where steeper slopes concentrate runoff. Generally, the shrub and grass mix and gravel in the soil surface horizon armor it from an abundance of water flow patterns. -
Number and height of erosional pedestals or terracettes:
There should not be pedastals present, but terracettes can form occasionally. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground is expected to be 50% -
Number of gullies and erosion associated with gullies:
None are expected on this site. -
Extent of wind scoured, blowouts and/or depositional areas:
None expected. -
Amount of litter movement (describe size and distance expected to travel):
Herbaceous litter is moved by wind and water and the distance can be several feet or more in open areas. Woody litter tends to stay in place. Long lived perennial plants retain litter under the canopy. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
The soil surface is aided in it's resistance to erosion by gravel (avg. 20%) and biological crust (2% - 7%). -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface to 9" loamy fine sand that is single grain; loose. Notice: the soil survey for the area and map unit that is being observed should be referenced for accurate information regarding the unique characteristics of that soil. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Shallow slopes promote even plant distribution of a shrub/grassland mix and on steeper slopes the vegetation becomes more uneven. Plant community composition: Shrubs (10-20% canopy, 5-10% basal); Grasses (0-5% canopy, 0-2% basal); Forbs (0-3% canopy, 0-2% basal); Trees (0-1% canopy, 0-1% basal); Biological Crust (0-10%). -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None expected. -
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:
ShrubsSub-dominant:
Grasses > ForbsOther:
TreesAdditional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
The mortality of most shrubs, grasses, forbs and trees is < 10% except during prolonged, severe drought conditions. Short term winter drought affects trees and shrubs the most and short term summer drought affects forbs and grasses. Expect cyclical higher mortality on shorter lived grasses, shrubs and forbs, such as sand dropseed, squirreltail, broom snakeweed and globemallow. -
Average percent litter cover (%) and depth ( in):
Most litter will accumulate below plant canopies or near plant bases. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Average annual production on this site is expected to be 350 to 450 lbs./ac. in a year of average annual precipitation. -
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:
Cheatgrass (Bromus tectorum) is commonly found in small amounts on the site (< 2 percent). During years of above average winter and spring moisture the composition of this may increase slightly. Severe disturbance may cause an increase in this or other invasive plants creating a potential for a shortened fire frequency on the site which could result in crossing a threshold to a state with increased introduced annual plants and fewer native shrubs. -
Perennial plant reproductive capability:
The only natural limitations to reproductive capability are weather related and natural disease or herbivory that reduces reproductive capability. All plants native to the site are adapted to the climate and are capable of producing seeds, stolons and rhizomes in all but the most severe droughts.
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