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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
MLRA notes
Major Land Resource Area (MLRA): 051X–High Intermountain Valleys
This MLRA encompasses the San Luis Valley in south central Colorado and the Taos Plateau and Taos alluvial piedmonts of north central New Mexico. As part of the northern portion of the Rio Grande Rift, the MLRA consists of large, alluvium filled basins washed down from adjacent mountain ranges. The Rio Grande River flows through this MLRA, continuing its long function of carrying mountain sediment down to the basin. Cenozoic volcanism is an extensive characteristic of the MLRA where large basalt flows with volcanic hills and domes are abundant.
Classification relationships
NRCS:
Major Land Resource Area 51, High Intermountain Valleys (United States Department of Agriculture, Natural Resources Conservation Service, 2006).
USFS:
331J – Northern Rio Grande Basin M331Ic > 331Ja - San Luis Valley, 331Jb - San Luis Hills and 331C - Mogotes
EPA:
22 - Arizona/New Mexico Plateau > 22a - San Luis Shrublands and Hills ; 22b -San Luis Alluvial Flats and Wetlands ; 22c - Salt Flats; 22e - Sand Dunes and Sand Sheets and 22f -Taos Plateau (Griffith, 2006).
USGS:
Southern Rocky Mountain ProvinceEcological site concept
The Playa is an upland run-on basin on the landscape, with no outlet. The soils have slow permeability and the surface layer thickness ranges from 2 to 5 inches thick. This site harbors two zones with somewhat different vegetation communities. These zones are based on the length of the period of inundation.
Associated sites
R051XA001NM Loamy
This ecological site is commonly positioned upslope and adjacent to the Playa site.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Atriplex canescens
(2) Gutierrezia sarothraeHerbaceous (1) Pascopyrum smithii
(2) AmaranthusPhysiographic features
This site occurs on a lava plateau.
Table 2. Representative physiographic features
Landforms (1) Playa floor
(2) Playa step
Runoff class Low Flooding frequency None Ponding duration Long (7 to 30 days) Ponding frequency Frequent Elevation 7100 – 8600 ft Slope 0 – 2 % Ponding depth 0 – 65 in Water table depth 5 – 70 in Aspect Aspect is not a significant factor Table 3. Representative physiographic features (actual ranges)
Runoff class Low Flooding frequency None Ponding duration Long (7 to 30 days) Ponding frequency Frequent Elevation 7100 – 8600 ft Slope 0 – 2 % Ponding depth 0 – 65 in Water table depth 5 – 70 in Climatic features
Mean annual precipitation varies from 9 to 15 inches. Departures from the average of 4 inches or more are common. Approximately 50 percent of this moisture occurs during the vegetative growth period, April through September. Over 20 percent of the precipitation comes in the form of high intensity summer thunderstorms which influence the presence and production of warm-season plants. Winter and early spring moisture in the form of rain or snow influences the presence and production of cool-season plants. This moisture also influences maximum shrub growth.
Mean annual temperature varies from 64 degrees F in July to 21 degrees F in January. The average last killing frost in the spring is May 30 and the first killing frost in the fall is September 30. The frost-free period is approximately 120 days, but freezing temperatures have been recorded every month except July and August.
Wind velocities are relatively light most of the year with stronger winds occurring in the spring and early summer. These winds increase transpiration rates of plants and rapidly dry the surface soil.Table 4 Representative climatic features
Frost-free period (characteristic range) 70-90 days Freeze-free period (characteristic range) 100-110 days Precipitation total (characteristic range) 10-20 in Frost-free period (actual range) 70-90 days Freeze-free period (actual range) 100-120 days Precipitation total (actual range) 10-20 in Frost-free period (average) 80 days Freeze-free period (average) 110 days Precipitation total (average) 10 in Characteristic rangeActual rangeBarLineFigure 1. Monthly precipitation range
Characteristic rangeActual rangeBarLineFigure 2. Monthly minimum temperature range
Characteristic rangeActual rangeBarLineFigure 3. Monthly maximum temperature range
BarLineFigure 4. Monthly average minimum and maximum temperature
Figure 5. Annual precipitation pattern
Figure 6 Annual average temperature pattern
Climate stations used
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(1) CERRO [USC00291630], Questa, NM
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(2) SAN LUIS 1 S [USC00057430], San Luis, CO
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(3) MANASSA [USC00055322], La Jara, CO
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(4) TRES PIEDRAS [USC00299085], Ojo Caliente, NM
">Influencing water features
A playa is an internally drained area that receives run-on water from surrounding uplands by means of overland flow and throughflow. On wetter years the playa floor experiences ponding of surface water or at least a saturated soil profile to near the surface. On drier years, there may be no water table present withinthe playa floor and step profiles.
Soil features
The soils of this site are very deep. Soils on the playa floor are somewhat poorly drained or moderately well drained. Soils on the playa step are moderately well drained or well drained. They have slow permeability. The surface layer thickness ranges from 2 to 5 inches thick. The soil moisture regime is ustic aridic. The soil temperature regime is frigid.
Major soils correlated to this ecological site include: Chromic Haplotorrert or Ustic Aquicambids on the playa floor. Ustertic Haplocambids on the playa step. There are no existing series.Table 5. Representative soil features
Parent material (1) Alluvium – basalt
Surface texture (1) Silty clay loam
(2) Silty clay
(3) Silt loam
Drainage class Somewhat poorly drained to well drained Permeability class Slow Depth to restrictive layer 60 – 80 in Soil depth 60 – 80 in Surface fragment cover <=3" 2 – 40 % Surface fragment cover >3" 1 – 20 % Available water capacity
(Depth not specified)0.13 – 0.19 in Calcium carbonate equivalent
(Depth not specified)Not specified Electrical conductivity
(Depth not specified)0 – 2 mmhos/cm Sodium adsorption ratio
(Depth not specified)Not specified Soil reaction (1:1 water)
(Depth not specified)7.2 – 7.8 Subsurface fragment volume <=3"
(Depth not specified)0 – 5 % Subsurface fragment volume >3"
(Depth not specified)Not specified Table 6. Representative soil features (actual values)
Drainage class Somewhat poorly drained to well drained Permeability class Slow Depth to restrictive layer 60 – 80 in Soil depth 60 – 80 in Surface fragment cover <=3" 2 – 40 % Surface fragment cover >3" 1 – 20 % Available water capacity
(Depth not specified)0.13 – 0.19 in Calcium carbonate equivalent
(Depth not specified)0 % Electrical conductivity
(Depth not specified)0 – 2 mmhos/cm Sodium adsorption ratio
(Depth not specified)0 Soil reaction (1:1 water)
(Depth not specified)7.2 – 7.8 Subsurface fragment volume <=3"
(Depth not specified)0 – 5 % Subsurface fragment volume >3"
(Depth not specified)0 % Ecological dynamics
The Playa Ecological Site has no surface drainage outlet. This site is located in a receiving position that collects runoff from adjacent upland sites in response to precipitation events. The water from this site escapes only by evaporation or subsurface drainage. The kinds and amount of vegetation existing on this site are influenced by the amount and timing of precipitation events, as well as the duration of ponding. Given the random pattern of the monsoon rains, some playas are inundated for several months, while adjacent sites may be totally dry for the entire season. This creates a highly variable mosaic of the type and volume of vegetation produced each year. As the amount of available vegetative data is limited to one season, additional multi-year collection is recommended.
Some of the sites have been excavated in an attempt to create more reliable water holding facilities to water livestock.
While livestock grazing was evident on several sites, no attempt was made to incorporate any grazing impacts into this analysis or STM. This decision was based on the lack of adequate data to form accurate conclusions.
The playas play an important role in providing forage for wildlife at critical times of the year. Any management strategy should incorporate the site into the larger context of the surrounding landscape. The playas should not be fenced out.
The historical fire return interval for this area was approximately 10 to 20 years. (Guyette and others, 2012).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 2 submodel, plant communities
State 1
Current PotentialThis state describes the playa during non-inundated periods.
Characteristics and indicators. The primary indicators of this state is the presence of vegetation and the lack of inundation.
Resilience management. This state is resilient in the absence of mechanical disturbance such as ditching and draining.
Dominant plant species
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fourwing saltbush (Atriplex canescens), shrub
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western wheatgrass (Pascopyrum smithii), grass
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lambsquarters (Chenopodium album), other herbaceous
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pigweed (Amaranthus), other herbaceous
Community 1.1
Playa Floor: Pigweed, Lambsquarter, and Western WheatgrassThis community is the current existing community for the non-inundated playa floor. The dominant grass is western wheatgrass (Pascopyrum smithii) while the dominant forbs are pigweed (Amaranthus) and lambsquarter (Chenopodium album). Shrubs are absent from this community.
Resilience management. light to moderate grazing.
Dominant plant species
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western wheatgrass (Pascopyrum smithii), grass
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pigweed (Amaranthus), other herbaceous
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lambsquarters (Chenopodium album), other herbaceous
Figure 7. Annual production by plant type (representative values) or group (midpoint values)
Table 7. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Forb 0 1193 2385 Grass/Grasslike 0 145 291 Total 0 1338 2676 Community 1.2
Playa Step: Pigweed, Lambsquarter, Western Wheatgrass, and Fourwing SaltbushThis community is the current existing community for the step. The primary distinguishing feature is the presence of shrubs. Western wheatgrass is the dominant grass, while pigweed and lambsquarter are the dominant forbs. Shrubs present include fourwing saltbush (Atriplex canescens), greasewood (Gutierrezia sarothrae), rabbitbrush (Chrysothamnus), and sagebrush (Artemesia).
Resilience management. Light to moderate grazing.
Dominant plant species
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fourwing saltbush (Atriplex canescens), shrub
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rabbitbrush (Chrysothamnus), shrub
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broom snakeweed (Gutierrezia sarothrae), shrub
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western wheatgrass (Pascopyrum smithii), grass
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pigweed (Amaranthus), other herbaceous
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lambsquarters (Chenopodium album), other herbaceous
Figure 8. Annual production by plant type (representative values) or group (midpoint values)
Table 8. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Forb 0 2071 4143 Grass/Grasslike 19 154 289 Shrub/Vine 0 37 75 Total 19 2262 4507 State 2
InundatedIn this state, the playa floor is inundated by run-on water to the degree that it cannot sustain vegetation. The step is also affected, though to a lesser degree.
Characteristics and indicators. Standing water, limited vegetation.
Resilience management. The primary challenges to resilience are ditching and draining through mechanical disturbance.
Dominant plant species
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fourwing saltbush (Atriplex canescens), shrub
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broom snakeweed (Gutierrezia sarothrae), shrub
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rabbitbrush (Chrysothamnus), shrub
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western wheatgrass (Pascopyrum smithii), grass
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pigweed (Amaranthus), other herbaceous
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lambsquarters (Chenopodium album), other herbaceous
Community 2.1
Inundated Playa FloorThe playa floor is ponded to a degree that prevents vegetative growth.
Community 2.2
Inundated Playa Step: Western Wheatgrass, Pigweed, Lambsquarters, Fourwing Saltbush, RabbitbrushInundation can significantly affect the vegetation on the site by reducing the production and altering the species composition. The dominant grass is western wheatgrass, while pigweed and lambsquarter are the dominant forbs. fourwing saltbush, rabbitbrush, and sagebrush may be present as the dominant shrubs.
Dominant plant species
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rabbitbrush (Chrysothamnus), shrub
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fourwing saltbush (Atriplex canescens), shrub
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western wheatgrass (Pascopyrum smithii), grass
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pigweed (Amaranthus), other herbaceous
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lambsquarters (Chenopodium album), other herbaceous
Transition T1A
State 1 to 2Inundation from overland flow and a high water table, normally following the monsoon rains.
Context dependence.Extended inundation, ditching and draining.
Key drivers
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Precipitation (monthly scale)
Restoration pathway R2A
State 2 to 1A non-inundated period of sufficient duration to allow vegetation to re-establish.
Context dependence.Prolonged inundation.
Additional community tables
Table 9. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Grasses 0–291 western wheatgrass PASM Pascopyrum smithii 0–291 – Forb2 Forbs 0–2385 lambsquarters CHAL7 Chenopodium album 1–1378 – little hogweed POOL Portulaca oleracea 0–1319 – redroot amaranth AMRE Amaranthus retroflexus 0–744 – curly dock RUCR Rumex crispus 0–106 – prostrate knotweed POAV Polygonum aviculare 0–34 – burningbush BASC5 Bassia scoparia 0–30 – Table 10. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Grasses 19–289 western wheatgrass PASM Pascopyrum smithii 19–289 – false buffalograss MUSQ3 Munroa squarrosa 0–116 – Forb2 Forbs 0–4143 redroot amaranth AMRE Amaranthus retroflexus 0–2734 – lambsquarters CHAL7 Chenopodium album 0–1353 – burningbush BASC5 Bassia scoparia 0–458 – little hogweed POOL Portulaca oleracea 0–140 – prickly Russian thistle SATR12 Salsola tragus 0–59 – prostrate knotweed POAV Polygonum aviculare 0–16 – Shrub/Vine3 Shrubs 0–75 fourwing saltbush ATCA2 Atriplex canescens 0–75 – basin big sagebrush ARTRT Artemisia tridentata ssp. tridentata 0–17 – rabbitbrush CHRYS9 Chrysothamnus 0–14 – plains pricklypear OPPO Opuntia polyacantha 0–9 – broom snakeweed GUSA2 Gutierrezia sarothrae 0–2 – Table 11. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 12. Community 2.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
Wildlife:
This ecological site provides a critical seasonal source of high quality forage to local wild ungulates and other species, particularly during a drought.
Livestock:
This ecological site provides seasonal high quality forage for livestock.Hydrological functions
A playa is an internally drained area that receives run-on water from surrounding uplands by means of overland flow and throughflow. On wetter years the playa floor experiences ponding of surface water or at least a saturated soil profile to near the surface. On drier years, there may be no water table present within playa floor profiles.
Recreational uses
The Playas site is inappropriate for most recreational uses due to ponding and high shrink-swell activity of the soils.
Wood products
Trees do not grow on this site.
Supporting information
Inventory data references
Rio Grande Del Norte Monument in North Central New Mexico.. Vegetative data was collected from 9 sites, both from the playa floors and steps.
References
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Guyette, R.P., M.C. Stambaugh, D.C. Dey, and R. Muzika. 2012. Predicting Fire Frequency with Chemistry and Climate. Ecosystems 15:322–335.
Other references
Chapman, S.S., G.E. Griffith, J.M. Omernik, A.B. Price, J. Freeouf, and D.L. Schrupp. 2006. Ecoregions of Colorado. (2-sided color posterwith map, descriptive text, summary tables, and photographs). U.S. Geological Survey, Reston, VA. Scale 1:1,200,000.
Cleland, D.T.; Freeouf, J.A.; Keys, J.E.; Nowacki, G.J.; Carpenter, C.A.; and McNab, W.H. 2007. Ecological Subregions: Sections andSubsections for the conterminous United States. Gen. Tech. Report WO-76D [Map on CD-ROM] (A.M. Sloan, cartographer). Washington,DC: U.S. Department of Agriculture, Forest Service, presentation scale 1:3,500,000; colored.
United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.Contributors
Laura Craven, NRCS Soil Sientist
Doug Whisenhunt, NRCS Ecological Site SpecialistApproval
Kirt Walstad, 5/06/2025
Acknowledgments
Jim Aramendariz, New Mexico NRCS State Range Conservationist. Daniel Romero, New Mexico NRCS Area Range Conservationist. Laura Craven, NRCS Soil Scientist. Abigail Clapp, NRCS Soil Scientist. Paul Rindfleisch, NRCS Soil Scientist.
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) Doug Whisenhunt Laura Craven Contact for lead author Date 09/26/2023 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None. -
Presence of water flow patterns:
None. Minor water flow patterns may be present on bare areas resulting from ponded water, however they will be short and disconnected. -
Number and height of erosional pedestals or terracettes:
None. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground ranges from 5 to 20 percent based on new plant growth following the inundation period. -
Number of gullies and erosion associated with gullies:
None. -
Extent of wind scoured, blowouts and/or depositional areas:
None. -
Amount of litter movement (describe size and distance expected to travel):
None. Expect minimal to very short movement of small sized herbaceous litter during intense rainfall events. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
The stability class ranges from 2 to 5. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
The most common soil surface structure is granular. When it is dry, most of the time the soil structure is sand size aggregates of silt and clay (wind blown, loose dry consistence). The soil organic matter is 1 to 2 percent. The A horizon typical colors are: dry 10YR 4/4, 10YR 4/3, and 10YR 3/3; moist 10YR 5/3, 10YR 5/4. The A horizon thickness is typically 3 cm, and can range to 8 cm. The soil surface texture is silty clay loam or silty clay. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Diverse grass, forb and shrub functional/structural groups and diverse root structure/patterns reduces raindrop impact and slows runoff providing increased time for infiltration to occur. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Usually none. -
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:
Forbs on both the playa floor and the playa step.Sub-dominant:
Grasses on the playa floor; Grasses>shrubs on the playa step.Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Mortality and decadence are minimal. -
Average percent litter cover (%) and depth ( in):
Litter is essentially not existent on the playa floor, and averages less than .5 inch on the playa step. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
The representative value for the total annual production for the playa floor is 1,338 pounds per acre while the playa step averages 2,262. -
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:
Russian thistle and burningbush are potential invaders on both the playa floor and the playa step. -
Perennial plant reproductive capability:
High on the playa step. Very few perennials can survive the lengthy inundation period on the playa floor.
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