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Conservation Service

Ecological site R035XB028NM

Sandy Bottom 6-10"

Accessed: 11/23/2024

Home / Esd catalog / MLRA 035X / Ecological site R035XB028NM

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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.

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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	(1) Atriplex canescens
Herbaceous	(1) Pascopyrum smithii (2) Achnatherum hymenoides

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Physiographic features

This site occurs on flood plains of valley floors and eolium-mantled high flood plains adjacent to the San Juan River or Chaco River. It receives some additional moisture from rare to frequent flooding and is influenced by a fluctuating water table. It occurs on all exposures. Slopes range from 0 to 1 percent. Elevations range from 4,600 to 6,000 feet.

Table 2. Representative physiographic features

Landforms	(1) Flood plain
Flooding duration	Very brief (4 to 48 hours)
Flooding frequency	Rare to occasional
Ponding frequency	None
Elevation	4,600 – 6,000 ft
Slope	3%
Water table depth	60 – 70 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 summer rainfall occurs as brief, sometimes heavy, thunderstorms. Most of the moisture from November through March comes as snow. Winds of high velocity during late winter and early spring are common.

Mean temperature for the hottest month, July, is about 83 degrees F. Mean temperature for the coldest month, January, is about 27 degrees F. Extreme temperatures of 104 degrees F and –17 degrees F have been recorded. The frost-free period ranges from 140 to 160 days.

The cool-season plants start growth in March and end with plant maturity and seed dissemination about mid-June. During June, July, August, and September, the warm-season plants make optimum growth taking advantage of the warm temperature and moisture 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 during the fall-winter-spring months influences cool-season plants.

Table 3. Representative climatic features

Frost-free period (average)	160 days
Freeze-free period (average)	165 days
Precipitation total (average)	10 in

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Line

Figure 2. Monthly precipitation range

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Figure 3. Monthly average minimum and maximum temperature

Soil features

The soils are very deep and well drained. They are formed in recent alluvium derived from sandstone and quartzite. Surface textures include very fine sandy loam and sand. The subsoil has textures of fine sand, very fine sandy loam, sand, and loamy fine sand. Permeability is moderate to moderately rapid. Available water holding capacity is very low to low. Runoff is negligible to low, and the hazard of water erosion is none to slight. The hazard of soil blowing is severe. The depth to water table is 5 to 6 feet. They are non- to slightly saline (EC 0-8), non sodic (SAR 0-5), and slightly to strongly alkaline (pH 7.4-9.0).

Characteristic taxonomic units are:
Shiprock SSA:
147-Escavada Sand
160-Notal-Escavada-Riverwash Assoc. (Escavada part)
165-Jeddito-Escavada Assoc. (Escavada part)
Other soils included are:

Table 4. Representative soil features

Surface texture	(1) Sand (2) Very fine sandy loam
Family particle size	(1) Sandy
Drainage class	Well drained
Permeability class	Moderate to moderately rapid
Soil depth	60 – 70 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	2 – 3 in
Calcium carbonate equivalent (0-40in)	1 – 5%
Electrical conductivity (0-40in)	8 mmhos/cm
Sodium adsorption ratio (0-40in)	5
Soil reaction (1:1 water) (0-40in)	7.4 – 9
Subsurface fragment volume <=3" (Depth not specified)	5%
Subsurface fragment volume >3" (Depth not specified)	Not specified

Ecological dynamics

This site has a plant community made up primarily of mid- and short grasses and some shrubs. In the historic climax plant community, there is a mixture of cool- and warm-season grasses and shrubs. Plant species most likely to invade or increase on this site when it deteriorates are saltcedar, Russian olive, cheatgrass, Russian thistle, goldenweed, rubber rabbitbrush and annual forbs. Continuous livestock grazing during winter and spring will decrease the cool-season grasses, which are replaced by lower forage value grasses and shrubs.

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 text

Ecosystem states

1. Saltcedar-Invaded Plant Community

State 1 submodel, plant communities

1.1. Saltcedar-Invaded Plant Community

State 1
Saltcedar-Invaded Plant Community

Community 1.1
Saltcedar-Invaded Plant Community

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	360	510	600
Shrub/Vine	180	255	300
Forb	60	85	100
Total	600	850	1000

Figure 5. Plant community growth curve (percent production by month). NM0379, R035XB028NM-Sandy Bottom 6 to 10 inch -Reference State. R035XB028NM-Sandy Bottom 6 to 10 inch-Reference State.

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

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Grass/Grasslike
1	western wheatgrass			128–170
	western wheatgrass	PASM	Pascopyrum smithii	128–170	–
2	alkali sacaton			85–128
	alkali sacaton	SPAI	Sporobolus airoides	85–128	–
3	Indian ricegrass			128–170
	Indian ricegrass	ACHY	Achnatherum hymenoides	128–170	–
4	sand dropseed			17–34
	sand dropseed	SPCR	Sporobolus cryptandrus	17–34	–
5	spike dropseed			0–9
	spike dropseed	SPCO4	Sporobolus contractus	0–9	–
6	giant dropseed			0–9
	giant dropseed	SPGI	Sporobolus giganteus	0–9	–
7	galleta			0–26
	James' galleta	PLJA	Pleuraphis jamesii	0–26	–
8	saltgrass			0–9
	saltgrass	DISP	Distichlis spicata	0–9	–
10	other perennial grasses			0–43
	Grass, perennial	2GP	Grass, perennial	0–43	–
Forb
11	perennial forbs			17–43
	Forb, perennial	2FP	Forb, perennial	17–43	–
12	annual forbs			0–43
	Forb, annual	2FA	Forb, annual	0–43	–
Shrub/Vine
13	saltcedar			128–170
	saltcedar	TARA	Tamarix ramosissima	128–170	–
	spineless horsebrush	TECA2	Tetradymia canescens	128–170	–
14	fourwing saltbush			43–85
	fourwing saltbush	ATCA2	Atriplex canescens	43–85	–
15	rubber rabbitbrush			0–26
	rubber rabbitbrush	ERNAG	Ericameria nauseosa ssp. nauseosa var. glabrata	0–26	–
16	broom snakeweed			0–26
	broom snakeweed	GUSA2	Gutierrezia sarothrae	0–26	–
17	other shrubs			0–43
	Shrub (>.5m)	2SHRUB	Shrub (>.5m)	0–43	–

Interpretations

Animal community

Run-in water produces thickets of shrubs and some trees which supply habitat for various wildlife species. These corridors are used as travel lanes by larger animals.

Hydrological functions

Runoff is negligible to low, and the hazard of water erosion is none to slight. The depth to water table is 5 to 6 feet. Capillary water rises from a fluctuating water table in early spring. Rainfall and floodwater wet the profile in the late summer.

Recreational uses

This site is characterized by flood plains, providing a stark contrast to the surrounding uplands. Bird watching, hunting, and horseback riding are a few of the popular activities suited to this site.

Wood products

This site has no significant value for wood products.

Other products

Grazing: This site is suitable for yearlong grazing by all classes of livestock and is easily traversed. Planned grazing systems adapt well to use on this site. When the stream bottoms and floodplains are in flood stage, this site can be very hazardous to livestock. The soils have a high wind erosion hazard rating leaving overgrazed areas especially susceptible to accelerated erosion.

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	T29N R16W S20
General legal description	Along the Chaco River, 7-8 miles ESE of Shiprock, NM –NW1/4 Sec. 20, T29N, R16W - Navajo Reservation, NM.

Contributors

David Trujillo
John Tunberg
Michael Carpinelli
Unknown

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
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:

Download reference sheet