Natural Resources
Conservation Service

Ecological site R035XD419AZ

Loamy Wash
7-11" p.z.

Accessed: 06/29/2026

Home / esd CATALOG / MLRA 035X / ecological site R035XD419AZ

USC

Metric

General information

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): 035X–Colorado Plateau

AZ CRA 35.4 – Colorado Plateau Cold Sagebrush – Grasslands

Elevations range from 4200 to 5100 feet and precipitation averages 7 to 11 inches. Vegetation includes winterfat, fourwing saltbush, buckwheat species, needlegrass, bottlebrush squirreltail, Indian ricegrass, black grama, blue grama, sideoats grama, gyp dropseed, and galleta. The soil temperature regime is mesic and the soil moisture regime is typic aridic. This unit occurs within the Colorado Plateau Physiographic Province and is characterized by a sequence of flat to gently dipping sedimentary rocks eroded into plateaus, valleys and deep canyons. Sedimentary rock classes dominate the plateau with volcanic fields occurring for the most part near its margin.

Associated sites

R035XD414AZ	Sandy Loam Upland 7-11" p.z. Sandy Loam Upland, 7-11" p.z.

R035XD414AZ

Sandy Loam Upland 7-11" p.z.

Sandy Loam Upland, 7-11" p.z.

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	(1) Sporobolus cryptandrus

Download full description

Physiographic features

This site occurs on low stream terraces and flood plains adjacent to ephemeral drainages. It receives run-on moisture from a drainageway and adjacent ecological sites, especially during high entensity thunderstorms characteristic of the summer monsoon season. The soils of this site are deep to very deep. Slopes are relatively flat.

Table 2. Representative physiographic features

Landforms	(1) Flood plain (2) Stream terrace
Flooding duration	Brief (2 to 7 days)
Flooding frequency	Frequent
Ponding frequency	None
Elevation	3800 – 6500 ft
Slope	1 – 3 %
Ponding depth	0 in
Aspect	Aspect is not a significant factor

Climatic features

Winter-Summer moisture ratios are typically 70:30 on the west side of this LRU and shift to 60:40 on the east side. Late spring is usually the driest period, and early fall moisture can be sporadic. Summer rains fall June-September; moisture originates in the Gulf of Mexico and creates convective, usually brief, intense thunderstorms. Cool season moisture October-May tends to be frontal; it originates in the Pacific and the Gulf of California and falls in widespread storms with longer duration and lower intensity. Precipitation generally comes as snow December-February. Accumulations above 10 inches are not common, but can occur. Snow usually lasts 3-4 days, but can persist much longer. Summer daytime temperatures are commonly 95-100 F and, on occasion, exceed 105F. Winter air temperatures can regularly go below 15 F and have been recorded below -15 F.

Table 3 Representative climatic features

Frost-free period (average)	220 days
Freeze-free period (average)	150 days
Precipitation total (average)	10 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soils charicterized on this site are deep to very deep. They are slightly effervescent on the surface, increasing to strongly effervescent in the subsoil at and below 2 inches. The surface texture is stratified loam. The subsurface textures range from stratified loam to stratified fine sandy loam.

Soils mapped on this site include:

SSA623 Shivwits Area MU 41 Ives.

Table 4. Representative soil features

Parent material	(1) Alluvium – sandstone
Surface texture	(1) Stony loam
Family particle size	(1) Loamy
Drainage class	Well drained
Permeability class	Moderate
Soil depth	40 – 60 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	7.8 – 10.2 in
Calcium carbonate equivalent (0-40in)	5 – 20 %
Electrical conductivity (0-40in)	0 – 2 mmhos/cm
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	7.9 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	Not specified
Subsurface fragment volume >3" (Depth not specified)	Not specified

Ecological dynamics

The plant communities found on an ecological site are naturally variable. Composition and production will vary with yearly conditions, location, aspect, and the natural variability of the soils. The historical climax plant community represents the natural potential plant communities found on relict or relatively undisturbed sites. Other plant communities described here represent plant communities that are known to occur when the site is disturbed by factors such as grazing, fire, or drought.

Production data provided in this site description is standardized to air-dry weight at the end of the summer growing season. The plant communities described in this site description are based on near normal rainfall years.

NRCS uses a Similarity Index to compare existing plant communities to the plant communities described here. Similarity Index is determined by comparing the production and composition of a plant community to the production and composition of a plant community described in this site description. To determine Similarity Index, compare the production (air-dry weight) of each species to that shown in the plant community description. For each species, count no more than the maximum amount shown for the species, and for each group, count no more than the maximum shown for the group. Divide the resulting total by the total normal year production shown in the plant community description. If rainfall has been significantly above or below normal, use the total production shown for above or below normal years. If field data is not collected at the end of the summer growing season, then the field data must be corrected to the end of the year production before comparing it to the site description. The growth curve can be used as a guide for estimating production at the end of the summer growing season.

State and transition model

Custom diagram

Standard diagram

More interactive model formats are also available. View Interactive Models

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

State 1
Historic Climax Plant Community

Community 1.1
Historic Climax Plant Community

The historic Climax Plant Community for this site has not been described.

State 2
Heavy, Long-Term Grazing

Community 2.1
Heavy, Long-Term Grazing

The plant community described for this state has been heavily influenced by livestock grazing. This ecological site was probably one of the earliest to be grazed by domestic livestock. It is also where many of the earliest ponds were constructed to provide water for homesteads and livestock. The plant community is dominated by introduced annual grasses and forbs, with remnants of the more grazing tolerant native perennial grasses and forbs.

Figure 3. 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)
Forb	240	–	270
Grass/Grasslike	30	–	60
Total	270	–	330

Figure 4. Plant community growth curve (percent production by month). AZ0002 , 35.4 7-11" p.z. sand dropseed. Some growth in spring, most growth in summer rainy season..

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	0	0	5	5	25	50	15	0	0	0

Figure 5. Plant community growth curve (percent production by month). AZ3541 , 35.4 7-11" p.z. all sites. Most growth occurs in the spring and during the summer rainy season..

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	1	9	20	15	5	16	25	6	2	1	0

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 7. Community 2.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Common Native Perennial Summer Grasses			30–60
	sand dropseed	SPCR	Sporobolus cryptandrus	30–60	–
2	Occasional Native Perennial Summer Grasses			0–3
	James' galleta	PLJA	Pleuraphis jamesii	0–3	–
3	Common Introduced Annual Grasses			0–60
	Grass, annual	2GA	Grass, annual	0–60	–
Forb
4	Occasional Native Perennial Forbs			0–6
	globemallow	SPHAE	Sphaeralcea	0–6	–
5	Common Introduced Annual Forbs			240–270
	Russian thistle	SALSO	Salsola	240–270	–
6	Occasional Introduced Annual Forbs			0–6
	Forb, annual	2FA	Forb, annual	0–3	–
	redstem stork's bill	ERCI6	Erodium cicutarium	0–3	–

Supporting information

Type locality

Location 1: Mohave County, AZ
Township/Range/Section	T40 N. R11 W. S35
General legal description	Arizona, Mohave County, Hole-N-Wall Canyon, AZ 7 1/2 min. quad., NE 1/4, Sec. 35, T. 40 N., R. 11 W., Dutchman Flat.

Contributors

Larry D. Ellicott
Stephen Cassady
Steve Cassady

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

Natural ResourcesConservation Service