Natural Resources
Conservation Service
Ecological site R035XB021NM
Loamy Upland
7-10
Last updated: 5/20/2025
Accessed: 04/24/2026
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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.
Ecological site concept
This site occurs on very deep, well-drained soils on elevated stream terraces and fan remnants. Surface textures are fine sandy loam and sandy clay loam. Slopes range from 1 to 15 percent.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Atriplex canescens
Herbaceous (1) Pleuraphis jamesii
Physiographic features
This site occurs on gently undulating high stream terraces and fan remnants below mesas and cuestas. It does not benefit from run-in moisture from adjacent areas nor does it suffer from excessive loss from runoff. It occurs on all exposures. Slopes range from 1 to 15 percent. Elevations range from 4,900 to 6,300 feet.
Table 2. Representative physiographic features
Landforms (1) Alluvial fan
(2) Fan remnant
(3) Valley side
Flooding duration Very brief (4 to 48 hours) Flooding frequency None to rare Elevation 4900 – 6300 ft Slope 1 – 15 % Water table depth 60 in Aspect Aspect is not a significant factor Climatic features
Mean annual precipitation varies from 7 to 10 inches. About 60% of this moisture comes as rain from April through October. May and June are the driest months. Most of the moisture from November through March comes as snow. Winds of high velocity during late winter and early spring are common.
Mean temperatures for the hottest month, July, are about 83 degrees F. The coldest month is January when the mean temperature is about 27 degrees F. Extreme temperatures of 104 degrees F and –17 degrees F have been recorded. Frost-free period ranges from 140 to 160 days.
Cool-season plants start growth in March and end with plant maturity and seed dissemination about mid-June. Warm-season plants grow from June through September, taking advantage of the moisture and warmth from tropical air out of the Gulf of Mexico. About 40% of the total precipitation is received during these summer months. The other 60%, received from fall through spring, influences cool-season plants.Table 3 Representative climatic features
Frost-free period (average) 160 days Freeze-free period (average) 170 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
This is an upland site, and is not associated with water features or wetlands. During heavy rain events, this site may receive run-on moisture from landforms above and contribute runoff to landforms below.
Soil features
The soils are very deep and well drained. They are formed in alluvium derived from sandstone, shale, and quartzite. Surface textures include fine sandy loam and sandy clay loam. The subsoil has textures of gravelly sandy clay loam, gravelly sandy loam, clay loam, fine sandy loam, sandy clay loam, loam, sandy loam, and very cobbly coarse sand. Permeability is moderate. Available water capacity is moderate to high. Runoff is very low to medium, and the hazard of water erosion is very slight to moderate. The hazard of soil blowing is moderate to severe. The soils are non- to slightly saline (EC 0-8); non- to slightly sodic (SAR 0-13); and slightly to strongly alkaline (pH 7.4-9.0).
Shiprock SSA:
155-Mesa fine sandy loam
195-Tewa fine sandy loam
210-Mack-Mesa fine sandy loam
270-Fruitland sandy clay loam
295-Mesa sandy clay loamTable 4. Representative soil features
Surface texture (1) Fine sandy loam
(2) Sandy clay loam
(3) Clay loam
Family particle size (1) Loamy
Drainage class Moderately well drained to somewhat excessively drained Permeability class Slow to moderately slow Soil depth 60 – 0 in Surface fragment cover <=3" 0 – 10 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)4 – 6 in Electrical conductivity
(0-40in)0 – 8 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 13 Soil reaction (1:1 water)
(0-40in)7.4 – 9 Subsurface fragment volume <=3"
(Depth not specified)0 – 45 % Subsurface fragment volume >3"
(Depth not specified)0 – 36 % Ecological dynamics
This ecological site has a plant community made up primarily of short- and mid-grasses mixed with shrubs and a small percentage of forbs. In the historic climax plant community, there is a mixture of cool- and warm-season grasses.
Plant species most likely to invade or increase on this site when it deteriorates are Russian thistle, annual weeds, galleta, alkali sacaton, Greene’s rabbitbrush, and broom snakeweed. When this site is continuously grazed during winter and spring, cool-season grasses and palatable shrubs are replaced by lower value forage plantsState 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
Reference StateThis state represents the most ecologically stable conditions in terms of resistance to erosion. Moreover, this state has the highest potential for productivity and plant diversity.
Community 1.1
Reference Plant CommunityThis ecological site has a plant community made up primarily of short- and mid-grasses mixed with shrubs and a small percentage of forbs. In the historic climax plant community, there is a mixture of cool- and warm-season grasses.
Plant species most likely to invade or increase on this site when it deteriorates are Russian thistle, annual weeds, galleta, alkali sacaton, Greene’s rabbitbrush, and broom snakeweed. When this site is continuously grazed during winter and spring, cool-season grasses and palatable shrubs are replaced by lower value forage plants.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 280 360 440 Shrub/Vine 50 70 80 Forb 20 20 30 Total 350 450 550 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 0% Grass/grasslike foliar cover 10% Forb foliar cover 0% Non-vascular plants 0% Biological crusts 0% Litter 30% Surface fragments >0.25" and <=3" 0% Surface fragments >3" 0% Bedrock 0% Water 0% Bare ground 50% Figure 5. Plant community growth curve (percent production by month). NM0316 , R035XB021NM-Loamy Upland-6 to 10 inch-HCPC. R035XB021NM-Loamy Upland-6 to 10 inch-HCPC.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 6 6 7 6 6 5 11 14 12 12 8 7 Community 1.2
Galleta - Blue Grama Grassland with Mixed ShrubsThis phase is dominated by galleta and blue grama, and also contains a mix of shrubs.
Community 1.3
Galleta Grassland/ShrublandThis phase is dominated by galleta and mixed shrubs.
Pathway P1.1a
Community 1.1 to 1.2Continuous grazing.
Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Food and fiber: livestock forage
Pathway P1.2b
Community 1.2 to 1.1Prescribed grazing.
Conservation practices
Prescribed Grazing Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Food and fiber: livestock forage
Pathway P1.2a
Community 1.2 to 1.3Continuous grazing.
Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Food and fiber: livestock forage
Pathway P1.3a
Community 1.3 to 1.2Prescribed grazing.
Conservation practices
Prescribed Grazing Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Food and fiber: livestock forage
State 2
Native/Invasive Annuals StateThis state is a mix of native plants and non-native invasive annuals.
Transition T1A
State 1 to 2Season-long grazing providing little rest and recovery for preferred grazed plants during critical growing periods, coupled with high utilization. This results in the establishment of non-native, invasive plants.
Key drivers
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Livestock grazing or browsing
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Climate
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Nonnative plant species presence and/or establishment
Key ecosystem services affected
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Erosion control
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Nutrient cycling
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Food and fiber: livestock forage
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Climate regulation: carbon cycling and storage
Additional community tables
Table 7. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 galleta 90–110 2 Indian ricegrass 40–70 James' galleta PLJA Pleuraphis jamesii 25–50 – 3 squirreltail 20–50 squirreltail ELEL5 Elymus elymoides 0–25 – 4 blue grama 20–50 5 black grama 0–20 Powell's saltweed ATPO2 Atriplex powellii 0–10 – 6 sand dropseed 0–10 7 alkali sacaton 0–20 alkali sacaton SPAI Sporobolus airoides 150–200 – Forb, annual 2FA Forb, annual 0–5 – 8 Fendler's threeawn 0–5 mound saltbush ATOB Atriplex obovata 100–125 – 9 other perennial grasses 0–10 greasewood SAVE4 Sarcobatus vermiculatus 5–25 – Grass, perennial 2GP Grass, perennial 0–25 – Forb10 rose heath 0–5 Mojave seablite SUMO Suaeda moquinii 0–15 – 11 perennial forbs 5–10 fourwing saltbush ATCA2 Atriplex canescens 0–25 – Forb, perennial 2FP Forb, perennial 0–10 – 12 annual forbs 0–5 sickle saltbush ATFA Atriplex falcata 0–5 – Shrub/Vine13 fourwing saltbush 20–40 valley saltbush ATCU Atriplex cuneata 0–5 – 14 Greene's rabbitbrush 0–10 Shrub (>.5m) 2SHRUB Shrub (>.5m) 0–15 – 15 winterfat 0–40 16 broom snakeweed 0–10 17 shadscale saltbush 0–5 18 Bigelow rubber rabbitbrush 0–5 19 other shrubs 0–10 Table 8. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 1.3 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
This site provides habitat for numerous species of wildlife. Common mammals include coyote, gray fox, badger, porcupine, black-tailed jackrabbit, desert cottontail, Gunnison’s prairie dog, Steven’s woodrat, western harvest mouse, banner-tailed kangaroo rat, deer mouse, and pallid bat. A few of the common birds include mourning dove, cliff swallow, rock wren, and black-throated sparrow. The plains spadefoot toad is an amphibian common to the site. Reptiles include collared lizard, side-blotched lizard, gopher snake, and prairie rattlesnake. The shrub component native to this site furnishes valuable browse and provides multi-layered thermal, nesting, and hiding cover for many species.
Hydrological functions
This site normally receives approximately 7-10 inches of precipitation annually. Most summer rainfall occurs as brief, sometimes heavy, thunderstorms. Slopes range from 1-15 percent. Runoff is very low to medium, and the hazard of water erosion is very slight to moderate. As basal cover and litter are reduced, and the size of gaps between vegetation increases, surface soils become exposed to accelerated erosion. Pedestals, rills, and gullies may form.
Recreational uses
The natural rugged beauty of this site lends itself to outdoor activities such as sightseeing, bird-watching, wildlife photography, hiking, and horseback riding. Care must be taken to prepare for hot, dry summers and cold winters.
Wood products
This site has no significant value for wood products.
Other products
This site is suitable for yearlong grazing by all classes of livestock and is easily traversed. It will respond quickly to a system of grazing. This site is susceptible to erosion, particularly overgrazed areas, old roads, cattle trails, and concentration areas.
Other information
N/A
Supporting information
Inventory data references
The potential historic climax plant community has been determined by study of range relict areas or areas protected from excessive grazing. Trends in plant communities going from heavily grazed areas to lightly grazed areas, seasonal use pastures, and historical accounts have also been used.
Type locality
Location 1: San Juan County, NM Township/Range/Section T23N R19W S2 General legal description Tsin Nas Kid topographic quadrangle – about 2.5 miles NW of Two Grey Hills, NM. Navajo Indian Reservation Contributors
David Trujillo
Jerry Reioux
John Tunberg
Michael CarpinelliApproval
Kendra Moseley, 5/20/2025
Rangeland 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 04/24/2026 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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