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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 35.6 - Colorado Plateau Pinyon-Juniper-Sagebrush
Elevations range from 5500 to 7000 feet and precipitation averages 13 to 17 inches per year. Vegetation includes pinyon, juniper, big sagebrush, cliffrose, Mormon tea, muttongrass, prairie junegrass, squirreltail, western wheatgrass, and blue grama. The soil temperature regime is mesic and the soil moisture regime is aridic ustic. 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.Associated sites
DX035X02B611 Clay Loam Upland 13-17" p.z. Gravelly (PIED, JUOS)
Clay Loam Upland 13-17" p.z. Gravelly (PIED, JUOS)
F035XF620AZ Basalt Upland 13-17" p.z. (JUOS)
Basalt Upland 13-17" p.z. (JUOS)
Table 1. Dominant plant species
Tree (1) Juniperus osteosperma
(2) Pinus edulisShrub (1) Purshia stansburiana
(2) Artemisia tridentata ssp. wyomingensisHerbaceous (1) Hesperostipa comata
(2) Pleuraphis jamesiiPhysiographic features
This juniper-pinyon site occurs in an upland position. It does not receive any benefit from run-on moisture, but excessive run-off can occur because of steep slopes of 15 to 50 percent. Elevations range from 5800 to 6600 feet.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
Flooding frequency None Ponding frequency None Elevation 5800 – 6600 ft Slope 15 – 50 % Aspect Aspect is not a significant factor Climatic features
The climate of this land resource unit is semiarid with warm summers and cool winters. The mean annual precipitation ranges from 13 – 17 inches, but it is very erratic, often varying substantially from year to year. The majority of the precipitation comes from October through April. This precipitation comes as gentle rain or snow from frontal storms coming out of the Pacific Ocean. Snow is common from November through February. Generally no more than a few inches of snow accumulates, melting within a few days, but may last a week or more. The remaining precipitation comes from July through September as spotty, unreliable and sometimes violent thunderstorms. The moisture for this precipitation originates in the Gulf of Mexico (and the Pacific Ocean in the fall) and flows into the area on the north end of the Mexican monsoon. Late May through late June is generally a dry period. The mean annual air temperature ranges from 47 to 49 degrees Fahrenheit (F). The frost-free period (air temperature > 32 degrees F) ranges from 113 to 144 days (@ 50 percent probability). Strong winds are common, especially in the spring.
Table 3 Representative climatic features
Frost-free period (average) 140 days Freeze-free period (average) 160 days Precipitation total (average) 20 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
The characteristic soil of this site is shallow to moderately deep. The surface is covered with a layer of gravels, cobbles and a few stones. The surface layer is about 4 inches deep with a texture of loam to clay loam. The subsoil, from about 4 inches to generally about 20 inches, has a texture of clay loam to clay. Subsoil fragments make up from 50 to 95 percent (% volume). The water erosion hazard of the soil is moderate to very severe due to the slope and surface texture.
Typical taxonomic units include:
SSA-623 Shivwits Area MU's 20 Dermala family & Guy family, 14 Boquillas family & Showlow;
SSA-701 Grand Canyon area MU's 56 Kellypoint, 64 Lithic haplustalfs, 76 Luzena.Table 4. Representative soil features
Parent material (1) Colluvium – basalt
Surface texture (1) Very gravelly loam
(2) Very cobbly clay loam
(3) Very cobbly
Family particle size (1) Clayey
Drainage class Well drained Permeability class Very slow to slow Soil depth 15 – 40 in Surface fragment cover <=3" 20 – 30 % Surface fragment cover >3" 30 – 60 % Available water capacity
(0-40in)2.1 – 5.5 in Calcium carbonate equivalent
(0-40in)5 – 15 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)7.4 – 8.2 Subsurface fragment volume <=3"
(Depth not specified)15 – 35 % Subsurface fragment volume >3"
(Depth not specified)35 – 60 % Ecological dynamics
In the abscence of regular disturbance this site has a dominant overstory of pinyon and juniper (rarely exceeds 50%), with a scattered understory of shrubs and sparse grasses and forbs. Typically perennial plant spacing is 1.5-2 feet. Major disturbance such as fire or diseased trees will result in a balanced mixture of these grasses, forbs, and shrubs. They are strongly competitive, but will gradually allow pinyon and juniper to re-establish. After 25-40 years, medium sized trees will be co-dominant with shrubs - grasses and forbs will begin to decline. As trees begin to dominate the site and canopy cover exedds 30%, shrub component will decline as well. Continuous heavy grazing will accelerate this process and will allow native grasses to be replaced by cheatgrass and broom snakeweed.
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 Community1. In the absence of regular distrubance, this site has a dominant overstory of pinyon and juniper (rarely exceeds 50%) with a scattered understory of shrubs and sparse grasses and forbs. Typical perennial plant spacing is 1.5-2 ft.
1.1A. Major disturbance such as fire or diseased trees will result in a balanced mixture of these grasses, forbs and shrubs.
1.2A. The natives are strongly competitive, but will gradually allow pinyon and juniper to re-establish.
T1A. Application of (314) Brush Management will change the community to introduced grasses that have been seeded in the aftermath of the brush removal.
2. Plant community of introduced grasses and forbs.
T2A. Continuous grazing with some fire will reduce the introduced grasses and return the plant community to a co-dominance of the understory and overstory.
3. Plant community with some fires and after 25-40 years, medium sized trees will be in co-dominance with shrubs and grasses.
R3A. Continuous heavy grazing with no fire will decrease the understory species and as trees begin to dominate the site and canopy cover exceeds 30%, shrub component will decline as well.
T1B. With continuous heavy grazing the trees will dominate and the shrubs will decline along with the native grasses and forbs. This allows the invasion and dominance of the understory by cheatgrass and snakeweed.
T1C. With some fires and after 25-40 years, medium sized trees will be co-dominant with shrubs. Grasses and forbs will begin to decline.
T2B. Continuous and heavy grazing will remove the introduced species ability to compete allowing the invasion of annuals.
T3A. Continuous heavy grazing will accelerate this process and will allow native grasses to be replaced by cheatgrass and broom snakeweed.
4. Plant community of tree overtory with eroded soils and understory of cheatgrass, snakeweed and other annuals.
R4A. Brush Management, Prescribed Burning and Range Planting will change the plant community to introduced species.Forest overstory.Tree species: Utah juniper/Colorado pinyon<br /> Site index: 50-60<br /> Fuelwood (cords per acre): 6-8<br /> Fence posts (7') per acre: 50-60<br /> CMAI per year: 6 cu ft<br /> Productivity class: 1<br />
Table 5. Canopy structure (% cover)
Height Above Ground (ft) Tree Shrub/Vine Grass/
GrasslikeForb <0.5 – – – – >0.5 <= 1 – – 1-3% – >1 <= 2 – – – 1-3% >2 <= 4.5 – 3-5% – – >4.5 <= 13 – – – – >13 <= 40 40-60% – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 4. Plant community growth curve (percent production by month). AZ3512 , 35.6 13-17" p.z. Stansbury cliffrose. Growth begins in spring and continues through the summer. Stem elongation, flowering, and seed set occur in 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 0 5 20 20 30 20 5 0 0 0 Figure 5. Plant community growth curve (percent production by month). AZ3560 , 35.6 13-17" p.z. galleta. Growth begins in spring, but 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 5 20 5 30 35 5 0 0 0 Figure 6. Plant community growth curve (percent production by month). AZ3565 , 35.6 13-17" 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 5 40 40 5 0 0 5 5 0 0 Figure 7. Plant community growth curve (percent production by month). AZ3603 , 35.6 13-17" p.z. Wyoming big sagebrush. Most growth occurs in the summer. Seed set 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 0 5 15 20 20 20 10 10 0 0 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 7. Community 1.1 forest overstory composition
Common name Symbol Scientific name Nativity Height ft Canopy cover (%) Diameter in Basal area (square ft/acre) TreeUtah juniper JUOS Juniperus osteosperma Native 1-18 25-35 3-12 0 twoneedle pinyon PIED Pinus edulis Native 5-20 15-25 3-10 0 Table 8. Community 1.1 forest understory composition
Common name Symbol Scientific name Nativity Height (ft) Canopy cover (%) Grass/grass-like (Graminoids)needle and thread HECOC8 Hesperostipa comata ssp. comata Native 3–4 5–15 sideoats grama BOCU Bouteloua curtipendula Native 0.2–1.5 2–10 Indian ricegrass ACHY Achnatherum hymenoides Native 0.1–2 1–5 desert needlegrass ACSP12 Achnatherum speciosum Native 0.2–2.4 1–5 New Mexico feathergrass HENE5 Hesperostipa neomexicana Native 0.5–3 1–5 blue grama BOGR2 Bouteloua gracilis Native 0.1–1 1–5 James' galleta PLJA Pleuraphis jamesii Native 0.1–1 3–5 squirreltail ELELE Elymus elymoides ssp. elymoides Native 0.3–2 1–4 black grama BOER4 Bouteloua eriopoda Native 0.1–1.5 1–3 Shrub/SubshrubWyoming big sagebrush ARTRW8 Artemisia tridentata ssp. wyomingensis Native 0.5–4 1–10 broom snakeweed GUSA2 Gutierrezia sarothrae Native 0.1–1 1–10 Stansbury cliffrose PUST Purshia stansburiana Native 1–7 3–7 Sonoran scrub oak QUTU2 Quercus turbinella Native 1–5 1–4 mormon tea EPVI Ephedra viridis Native 0.5–3 1–3 fourwing saltbush ATCA2 Atriplex canescens Native 0.5–4 1–3 banana yucca YUBA Yucca baccata Native 0.1–2.5 1–2 Fremont's mahonia MAFR3 Mahonia fremontii Native 1–7 1–2 TreeUtah juniper JUOS Juniperus osteosperma Native 1–18 20–30 twoneedle pinyon PIED Pinus edulis Native 4–22 15–20 Interpretations
Animal community
The major factors influencing this site are lack of water, steep and stony slopes and winter snow cover. Typically, the site is used from late spring until early winter. Livestock distribution is poor - water development, cross-fencind and good grazing management are necessary.
This site may be used extensively by wildlife, especially mule deer. Tree removal or burning should be done in mosaics or small scattered patches to benefit big game use and provide an assortment of ecological successional stages for wildlife indigenous to this site. Snag and large tree removal may impact cavity-nesting birds. Sites with old growth trees, low herbaceous production or unsuitable soils should remain primarily in woodland cover. Ridges and arroyos should be maintained as travel and feeding corridors.Recreational uses
Hiking, hunting, photography and wildlife observation are recreational activites on this site.
Table 9. Representative site productivity
Common name Symbol Site index low Site index high CMAI low CMAI high Age of CMAI Site index curve code Site index curve basis Citation Utah juniper JUOS 50 60 5 6 – – – Supporting information
Type locality
Location 1: Mohave County, AZ Township/Range/Section T39N R12W S30 General legal description Wolf Hole Mountain West 7.5 minute quad; south end of Wolf Hole Mountain Contributors
Arthur Meen
Karlynn Huling
Larry D. Ellicott
Stephen CassadyRangeland 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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