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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.
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous Not specified
Physiographic features
This site occurs on moderately sloping mesas, upland valleys, and valley side slopes. The site is usually dissected by small drainageways which often erode quite readily when the vegetation has deteriorated. Slopes are nearly level to moderately sloping, 3 to 8 percent. Elevations are from 5,600 to 6,400 feet above sea level.
Table 2. Representative physiographic features
Landforms (1) Valley side
(2) Mesa
Flooding duration Very brief (4 to 48 hours) Flooding frequency Rare Elevation 5600 – 6400 ft Slope 3 – 8 % Aspect Aspect is not a significant factor Climatic features
This site has an arid, mild, dry climate with distinct seasonal temperature variations and large annual and diurnal temperature changes.
Mean annual precipitation varies from 7 to 10 inches. Deviations of 4 inches or more are quite common. Distribution is 65% during the native-plant growth period, which is from April through September. May and June are the dry months. During July, August, and September, 3.5 inches of precipitation influences the presence and production of warm-season plants. Late-fall and winter moisture is conducive to the production of cool-season plants, which usually begin growth in March and end with plant maturity and seed dissemination. This usually takes place in the early part of June when the moisture deficiency and warmer temperatures occur. The Gulf of Mexico is the principal source of moisture for summer precipitation which is characterized by brief afternoon thunderstorms. Winter moisture occurs as light rain or snow.
Temperatures vary from a monthly mean of 75 degrees F in July to 27 degrees F in January, and from an annual maximum of 106 degrees F to an annual minimum of -35 degrees F. The average last killing frost in the spring is May 8, and the average first killing frost in the fall is October 10. The frost-free season is approximately 160 days. Temperatures are conducive for native grass and forb growth from April through September. Maximum shrub growth occurs in the spring months.
The wind blows most frequently from an easterly direction; however, a majority of the stronger winds (10 to 25 miles per hour) are from a westerly quadrant. Spring is the windiest season. Average hourly wind velocities are near 6 miles per hour. Spring and summer winds increase transpiration rates of native plants and rapidly dry the surface soil. Small soil particles are often displaced by the wind near the soil surface and often results in structural damage to native plants, especially young seedlings.
Climate data were obtained from http://www.wrcc.sage.dri.edu/summary/climsmnm.html web site using 50% probability for freeze-free and frost-free seasons using 28.5 degrees F and 32.5 degrees F, respectively.Table 3 Representative climatic features
Frost-free period (average) 150 days Freeze-free period (average) 180 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
This site is not influenced by water from a wetland or stream.<br />
Soil features
The soils on this site are shallow to moderately deep. They are well-drained and sodium-affected. They have light-colored surfaces with textures ranging from very fine sandy loam to silty clay loam, 2 to 3 inches thick. The subsoils are clay and clay loam. Depth to shale bedrock is 14 to 24 inches. They are formed in material weathered from shale. Water intake rate is slow to very slow. Permeability is slow to very slow. The shallow soil and the sodium content restrict root penetration. Available water-holding capacity is 2.0 to 4.0 inches. Potential wind and water erosion is high.
Table 4. Representative soil features
Surface texture (1) Fine sandy loam
(2) Clay
(3) Silty clay loam
Family particle size (1) Clayey
Drainage class Well drained Permeability class Very slow to slow Soil depth 14 – 65 in Available water capacity
(0-40in)0 – 6 in Electrical conductivity
(0-40in)0 – 8 mmhos/cm Sodium adsorption ratio
(0-40in)5 – 30 Soil reaction (1:1 water)
(0-40in)7.9 – 9.6 Subsurface fragment volume <=3"
(Depth not specified)15 – 35 % Ecological dynamics
The aspect of vegetation on this site is a shrub/grassland mixture characterized by short- and mid-grasses; shrubs are quite noticeable. Perennial forbs are a minor component of the plant community. Annual forbs and grasses occur in relative abundance during spring months in years of above-average growing conditions.
Additional plants which usually grow on this site in varying amounts dependent on current growing season conditions are: fluffgrass, annual bromegrass, Rocky Mountain beeplant, sunflowers, showy daisy, cutleaf daisy, gumweed, bull thistle, Russian thistle, sixweeks grama, sixweeks fescue, and Indian paintbrush.
State and transition model
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 aspect of vegetation on this site is a shrub/grassland mixture characterized by short- and mid-grasses; shrubs are quite noticeable. Perennial forbs are a minor component of the plant community. Annual forbs and grasses occur in relative abundance during spring months in years of above-average growing conditions.
Additional plants which usually grow on this site in varying amounts dependent on current growing season conditions are: fluffgrass, annual bromegrass, Rocky Mountain beeplant, sunflowers, showy daisy, cutleaf daisy, gumweed, bull thistle, Russian thistle, sixweeks grama, sixweeks fescue, and Indian paintbrush.
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 120 210 300 Forb 20 35 50 Total 140 245 350 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 0% Grass/grasslike foliar cover 0% Forb foliar cover 0% Non-vascular plants 0% Biological crusts 0% Litter 10% Surface fragments >0.25" and <=3" 0% Surface fragments >3" 0% Bedrock 0% Water 0% Bare ground 70% Figure 5. Plant community growth curve (percent production by month). NM0908 , R035XB008NM-Sodic Slopes-HCPC. A mixed shrub/grassland characterized by short/mid-grasses with a minor component of forbs. .
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 7 10 10 25 30 10 3 0 0 Additional community tables
Table 7. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 88–105 alkali sacaton SPAI Sporobolus airoides 88–105 – 2 53–70 James' galleta PLJA Pleuraphis jamesii 53–70 – 3 18–35 needle and thread HECO26 Hesperostipa comata 18–35 – 4 35–53 Indian ricegrass ACHY Achnatherum hymenoides 35–53 – 5 11–18 sand dropseed SPCR Sporobolus cryptandrus 11–18 – 6 11–18 threeawn ARIST Aristida 11–18 – 7 18–35 blue grama BOGR2 Bouteloua gracilis 18–35 – 8 11–18 squirreltail ELEL5 Elymus elymoides 11–18 – Forb9 7–11 herb sophia DESO2 Descurainia sophia 71–11 – woolly plantain PLPA2 Plantago patagonica 7–11 – ragwort SENEC Senecio 7–11 – Shrub/Vine10 18–35 greasewood SAVE4 Sarcobatus vermiculatus 18–35 – 11 18–35 fourwing saltbush ATCA2 Atriplex canescens 18–35 – 12 11–18 shadscale saltbush ATCO Atriplex confertifolia 11–18 – 13 11–18 big sagebrush ARTR2 Artemisia tridentata 11–18 – 14 4–11 yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 4–11 – 15 succulent 4–11 16 4–11 plains pricklypear OPPO Opuntia polyacantha 4–11 – 17 7–11 broom snakeweed GUSA2 Gutierrezia sarothrae 7–11 – Interpretations
Animal community
Habitat for Wildlife:
This ecological site provides habitats which support a resident animal community that is characterized by pronghorn antelope, coyote, desert cottontail, Botta’s pocket gopher, deer mouse, raven, scaled quail, house finch, western spadefoot toad, and prairie rattlesnake. The loggerhead shrike and mockingbird are summer residents.
Hydrological functions
The runoff curve numbers are determined by field investigations using hydrologic cover conditions and hydrologic soil groups.
Hydrologic Interpretations
Soil Series-----------Hydrologic Group
Elias----------------------C
Huerfano-------------------?
Muff-----------------------?
Starlake-------------------D
Recreational uses
This site has low potential for outdoor recreation.
Wood products
No Data
Other products
Grazing:
This site is well suited for grazing use, when grazing within its capabilities, by cattle, sheep, horses, antelope, deer, and burros.
Under pressure of uncontrolled grazing the potential plant community deteriorates, and there is a marked increase in relative abundance of shrubs, cacti, and perennial and annual forbs. In severe deterioration, the site will consist predominantly of shrubs, annual forbs, and annual grasses, with lesser amounts of perennial grasses and large areas of unprotected soils.
Other information
Guide to Suggested Initial Stocking Rate Acres per Animal Unit Month
Similarity Index------------Ac/AUM
100 - 76------------------7.0 – 14.0
75 – 51-------------------9.0 – 18.0
50 – 26------------------11.0 – 22.0
25 – 0-------------------22.0+
Supporting information
Type locality
Location 1: San Juan County, NM Township/Range/Section T29 N R15 W S34 General legal description A typical pedon of Huerfano silty clay loam, in San Juan County, New Mexico, 3 miles east of Morgan Lake, 2,206 feet east and 1,254 feet south of the northwest corner of Section 34, T29N, R15W. Other references
Data collection for this site was done in conjunction with the progressive soil surveys within the San Juan River Valley, Mesas and Plateaus, Major Land Resource Area 35 of New Mexico. This site has been mapped and correlated with soils in the following soil surveys: San Juan, McKinley.
Characteristic soils are:
Elias, Huerfano, Muff, StarlakeContributors
Don Sylvester
Elizabeth Wright
John Tunberg
Michael CarpinelliRangeland 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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