Natural Resources
Conservation Service
Ecological site R042BB001NM
Alkali Flat, Desert Shrub
Accessed: 11/13/2024
General information
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.
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.
Associated sites
R042BB002NM |
Gyp Duneland Barren, Desert Shrub The Alkali Flat site is the source of gypsum for the dunefields of White Sands National Monument and White Sands Missile Range. |
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R042BB003NM |
Vegetated Gypsum Dunes, Desert Shrub The Alkali Flat site is the source of gypsum for the Vegetated Dunes of White Sands National Monument and White Sands Missile Range. |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
Not specified |
Herbaceous |
Not specified |
Physiographic features
This site occurs in basins on relict lakebeds. Slopes are flat averaging less than 2 percent. Elevation ranges from about 3500-4000 feet above sea level.
This site receives salts from groundwater inflow sources and runoff from adjoining piedmont slopes. These salts are concentrated on the surface by way of evaporation and act as a supply source for downwind gypsum dune formations.
Table 2. Representative physiographic features
Landforms |
(1)
Pluvial lake (relict)
|
---|---|
Ponding duration | Long (7 to 30 days) to very long (more than 30 days) |
Ponding frequency | Occasional to frequent |
Elevation | 3,500 – 4,000 ft |
Slope | 2% |
Water table depth | 30 – 60 in |
Aspect | Aspect is not a significant factor |
Climatic features
Annual average precipitation ranges from 7 to 12 inches. Wide fluctuations from year to year are common. At least one-half of the annual precipitation comes in the form of rainfall during July, August, and September. Precipitation in the form of snow or sleet averages less than 4 inches annually. The average annual air temperature is about 60 degree F. Summer maximums can exceed 100 degrees F. and winter minimums can go below zero. The average frost-free season exceeds 200 days and extends from April 1 to November 1. Both the temperature regime and rainfall distribution favor warm-season perennial plants on this site. Spring moisture conditions are only occasionally adequate to cause significant growth during this period of year. High winds from the west and southwest are common from March to June, which further tends to create poor soil moisture conditions in the springtime
Climate data was obtained from
http://www.wrcc.dri.edu/summary/climsmnm.html
Table 3. Representative climatic features
Frost-free period (average) | 205 days |
---|---|
Freeze-free period (average) | 227 days |
Precipitation total (average) | 12 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
The soils of this site are crystalline gypsiferous loamy coarse sands overlying a petrogypsic horizon.
They are very poorly drained and will occasionally pond water for a month or longer. They are strongly saline with Ec values ranging from 50 to well over 100.
Characteristic Soils Are:
MU-359 Gypsic Haplosalids, 0-1 percent slope. NM688-White Sands Soil Survey
MU-360 Petrogypsic haplosalid, 0-2 percent slopes. NM688-White Sands Soil Survey
Table 4. Representative soil features
Surface texture |
(1) Gypsiferous loamy coarse sand |
---|---|
Family particle size |
(1) Sandy |
Drainage class | Poorly drained |
Surface fragment cover <=3" | Not specified |
Surface fragment cover >3" | Not specified |
Electrical conductivity (0-40in) |
50 – 150 mmhos/cm |
Subsurface fragment volume <=3" (Depth not specified) |
Not specified |
Subsurface fragment volume >3" (Depth not specified) |
Not specified |
Ecological dynamics
The alkali flat site occurs on large deflation basins where the sediments consist mostly of gypsum and other evaporites. Erosion, high salt content, ponding and seasonal high water tables combine to make this site an extremely harsh environment. The lowest elevations of the Alkali Flat are devoid of vegetation. These areas can occasionally be subjected to extended periods of ponding, and seasonal fluctuations in ground water depth. Those areas of this ecological site that sit slightly higher topographically typically display scattered iodinebush. However, following instance of high rainfall, portions of these slightly higher areas can also become susceptible to ponding. Ponding duration and extent varies spatially and by rainfall event.
State and transition model
Figure 4. Alkali Flat Ecological Site Model
More interactive model formats are also available.
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More interactive model formats are also available.
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Click on state and transition labels to scroll to the respective text
Ecosystem states
State 1 submodel, plant communities
State 1
Barren
This state is characterized by the general lack of vegetation. The lowest areas are completly devoid of vegetation while areas that are slightly topographically higher may contain widely scattered plants.
Community 1.1
Bare
This area encompasses the lowest elevations across the Alkali Flat site and is devoid of vegetation. Ponding, erosion, high salt content, and seasonal high water tables prevent the establishment and growth of vegetation.
Community 1.2
Scattered Iodinebush
The higher portions of this site typically display sparse iodine bush. These areas are most common on the downwind side of the Alkali Flat. On the downwind side sands tend to accumulate in scattered patches across the flat. These areas provide niches for seedling catchment and establishment. Following high rainfall events, these areas may pond water and plants on higher ground are favored. Additionally, small vegetated islands are occasionally found along the outside edges of the Alkali Flat. These areas form where wind patterns allow some deposition. Surface salt crusts on the edges tend to be heavy, and may facilitate deposition. Species usually consist of alkali sacton and iodine bush.
Figure 8. 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 | 0 | 10 | 25 |
Forb | 0 | 0 | 0 |
Grass/Grasslike | 0 | 0 | 0 |
Microbiotic Crusts | 0 | 0 | 0 |
Total | – | 10 | 25 |
Table 6. Soil surface cover
Tree basal cover | 0% |
---|---|
Shrub/vine/liana basal cover | 0-1% |
Grass/grasslike basal cover | 0% |
Forb basal cover | 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 | 99-100% |
Pathway 1.1A
Community 1.1 to 1.2
On areas of this site that are slightly topographically higher,a drop in the water table, soil deposition, and seed dispersal may help to establish plants on previously bare areas. These conditions may result following periods of drought and high evaporation.
Pathway 1.2A
Community 1.2 to 1.1
Extended rainfall events and the associated ponding and rise in the water table can cause the the shift back to the bare community.
Additional community tables
Table 7. Community 1.2 plant community composition
Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
---|---|---|---|---|---|---|
Shrub/Vine
|
||||||
1 | Perennial Shrubs | 0–25 | ||||
iodinebush | ALOC2 | Allenrolfea occidentalis | 0–25 | 0 |
Interpretations
Animal community
The scarcity of vegetation, shallow groundwater, and high salinity combine to make this site provide only limited use to wildlife.
Hydrological functions
The groundwater table of the Alkali Flat is shallow most of the time. It fluctuates from the surface to a few feet deep. It contains high concentrations of evaporites resulting from the subsurface inflow of saline groundwater.
Recreational uses
This site is currently used for educational purposes by White Sands National Monument.
Wood products
This site has no significant value for wood products.
Other products
Gypsum
Supporting information
Other references
Bennett, J., Wilder, D., 2009. Physical resources foundation report, White Sands National Monunent, Natural Resource Report NPS/NRPC/NRR—2009/166. National Park Service, Fort Collins, Colorado.
Fryberger, S.G., 2000. Geological overview of White Sands National Monument. http://www.nature.nps.gov/geology/parks/whsa/geows/index.htm
Langford, R.P., Rose, J.M., White, D.E., 2009. Groundwater salinity as a control on development of eolian landscape: An example from White Sands of New Mexico. Geomorphology 105(2009) 39-49.
Contributors
David Trujillo
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) | |
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Contact for lead author | |
Date | |
Approved by | |
Approval date | |
Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
-
Presence of water flow patterns:
-
Number and height of erosional pedestals or terracettes:
-
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
-
Number of gullies and erosion associated with gullies:
-
Extent of wind scoured, blowouts and/or depositional areas:
-
Amount of litter movement (describe size and distance expected to travel):
-
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
-
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
-
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
-
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
-
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:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
-
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
-
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:
-
Perennial plant reproductive capability:
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The 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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