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Ecological site R030XC317AZ

Sandy Bottom 10-13" p.z.

Last updated: 10/21/2024
Accessed: 12/03/2024

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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.

MLRA notes

Major Land Resource Area (MLRA): 030X–Mojave Basin and Range

This unit occurs within the Basin and Range Province and is characterized by broad basins, valleys, and old lakebeds. Widely spaced mountains trending north to south occur throughout the area. Isolated, short mountain ranges are separated by an aggraded desert plain. The mountains are fault blocks that have been tilted up. Long alluvial fans coalesce with dry lakebeds between some of the ranges.

LRU notes

AZ LRU 30-3 – Upper Mohave Desert

Elevations range from 2800 to 4500 feet and precipitation averages 9 to 12 inches per year. Vegetation includes Joshua tree, blackbrush, creosotebush, ratany, bush muhly, big galleta, black grama, desert needlegrass, and Indian ricegrass. The soil temperature regime is thermic and the soil moisture regime is typic aridic.

Ecological site concept

This ecological site occurs in bottoms on narrow stream channels. Soils are deep sand, sandy loam to loamy sands throughout.

Similar sites

R030XC322AZ	Sandy Wash 10-13" p.z.

R030XC322AZ

Sandy Wash 10-13" p.z.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Acacia greggii (2) Hymenoclea salsola
Herbaceous	(1) Muhlenbergia porteri

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Physiographic features

This ecological site is found in a bottom position on narrow stream channels and low stream terraces of floodplains. It receives additional run-in moisture from surrounding ecological sites.

Table 2. Representative physiographic features

Landforms	(1) Channel (2) Stream terrace
Flooding frequency	Rare to occasional
Ponding frequency	Rare to occasional
Elevation	2,200 – 4,600 ft
Slope	1 – 3%
Aspect	Aspect is not a significant factor

Climatic features

The climate is arid and warm. Annual precipitation ranges from 10 to 13 inches. About 65 percent of the rainfall comes from October through May as gentle rain from Pacific storms which may last for a couple of days. The rest of the rainfall comes during the summer monsoon season from July through September as spotty, brief, intense thunderstorms. Snow rarely falls, and only remains on the ground a few hours at most. Annual air temperature ranges from 46 to 76 degrees F. The average frost-free period ranges from 121 to 231 days.

Table 3. Representative climatic features

Frost-free period (average)	231 days
Freeze-free period (average)	269 days
Precipitation total (average)	13 in

Bar

Line

Figure 2. Monthly precipitation range

Bar

Line

Figure 3. Monthly average minimum and maximum temperature

Soil features

Soils are deep to very deep. Surface textures are very gravelly sand, sandy loam, and gravelly sandy loam. Subsoil textures are gravelly loamy coarse sand, very cobbly coarse sand, very gravelly coarse sand, extremely gravelly sand, very gravelly sand, gravelly sandy loam, loamy sand and sand.

Available water capacity is very low to low.

Erosion hazard by water is slight to severe; by wind is slight to moderate. Soils are non-saline, non-sodic with pH range of 7.4-8.4. Soil temperature regime is thermic; moisture regime is typic aridic.

Landform and position is narrow stream channels and low stream terraces of floodplains.

Soil mapping units include Hualapai SSA (Arizo), Central Mohave SSA (Arizo), and So. Mohave SSA (Arizo, Ireteba, and Franconia).

Table 4. Representative soil features

Surface texture	(1) Gravelly sand (2) Very cobbly sandy loam (3) Extremely gravelly
Family particle size	(1) Sandy
Drainage class	Somewhat excessively drained to excessively drained
Permeability class	Moderately rapid to very rapid
Soil depth	60 in
Surface fragment cover <=3"	50 – 55%
Surface fragment cover >3"	15%
Available water capacity (0-40in)	2 – 2.5 in
Calcium carbonate equivalent (0-40in)	5 – 10%
Electrical conductivity (0-40in)	2 mmhos/cm
Soil reaction (1:1 water) (0-40in)	7.4 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	45 – 65%
Subsurface fragment volume >3" (Depth not specified)	45%

Ecological dynamics

Sandy Bottom, 10"-13" p.z., is a shrub dominated ecological site with occasional tree sized shrubs. Plant community recieves additional moisture from run-on events. A lush understory of perennial grasses, sub-shrubs and forbs is present. Annual forbs and grasses flourish following rainfall. Other than flash flooding, natural disturbances are rare. After introduction of non-native annuals (forbs and/or grasses), the shift in total productivity is shift increased seasonal herbaceous production following periods of rain. Dominant shrubs are creosote and white bursage. Assorted half-shrubs are widely scattered.

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

State 1
Historic Climax Plant Community

Community 1.1
Historic Climax Plant Community

The dominant aspect of the site is a grassland-shrub mix. Dropseeds, big galleta and bush muhly are the major grasses. Shrubs include catclaw acacia, white burrobush, fourwing saltbush and Mexican bladdersage. This site floods often, which may result in a good annual grass and forb growth.

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	141	275	545
Shrub/Vine	141	275	545
Forb	18	50	110
Total	300	600	1200

Table 6. Ground cover

Tree foliar cover	0%
Shrub/vine/liana foliar cover	1-3%
Grass/grasslike foliar cover	0-2%
Forb foliar 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	0%

Table 7. Canopy structure (% cover)

Height Above Ground (ft)	Tree	Shrub/Vine	Grass/ Grasslike	Forb
<0.5	–	–	–	0-2%
>0.5 <= 1	–	–	8-12%	–
>1 <= 2	–	–	–	–
>2 <= 4.5	–	18-22%	–	–
>4.5 <= 13	–	–	–	–
>13 <= 40	–	–	–	–
>40 <= 80	–	–	–	–
>80 <= 120	–	–	–	–
>120	–	–	–	–

Figure 5. Plant community growth curve (percent production by month). AZ3024, 30.3 10-13" p.z. upland sites. Growth begins in the spring and continues through the summer..

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	8	18	18	11	14	20	8	2	0	0

State 2
Historic Native Plant Community plus Introduced Annuals

Community 2.1
Non-native Annuals

This plant community resembles the historic native plant community, but exotic annuals have been introduced. Non-native species include Asian mustard (Brassica tournefortii), red brome, Mediterranean grass (Schismus spp.), and filaree. The flourish of non-native annuals that occurs following rainfalls may preclude native annuals.

Transition T1A
State 1 to 2

Introduction of non-native annual forb and grass seed.

Additional community tables

Table 8. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Grass/Grasslike
1				60–90
	bush muhly	MUPO2	Muhlenbergia porteri	60–90	–
2				6–30
	big galleta	PLRI3	Pleuraphis rigida	6–30	–
3				6–30
	spike dropseed	SPCO4	Sporobolus contractus	6–30	–
4				6–30
	sand dropseed	SPCR	Sporobolus cryptandrus	6–30	–
5				6–30
	mesa dropseed	SPFL2	Sporobolus flexuosus	6–30	–
6				6–30
	black grama	BOER4	Bouteloua eriopoda	6–30	–
7				6–30
	Indian ricegrass	ACHY	Achnatherum hymenoides	6–30	–
8				0–12
	low woollygrass	DAPU7	Dasyochloa pulchella	0–12	–
9				0–12
	slim tridens	TRMU	Tridens muticus	0–12	–
10				6–30
	Grass, perennial	2GP	Grass, perennial	6–30	–
11				0–12
	Grass, annual	2GA	Grass, annual	0–12	–
Forb
12				6–12
	beardtongue	PENST	Penstemon	6–12	–
13				6–12
	desert trumpet	ERIN4	Eriogonum inflatum	6–12	–
14				6–30
	Forb, perennial	2FP	Forb, perennial	6–30	–
15				0–12
	Forb, annual	2FA	Forb, annual	0–12	–
Shrub/Vine
16				30–60
	catclaw acacia	ACGR	Acacia greggii	30–60	–
17				6–30
	woolly fruit bur ragweed	AMER	Ambrosia eriocentra	6–30	–
18				30–60
	burrobrush	HYSA	Hymenoclea salsola	30–60	–
19				6–30
	fourwing saltbush	ATCA2	Atriplex canescens	6–30	–
20				6–30
	Mexican bladdersage	SAME	Salazaria mexicana	6–30	–
21				12–30
	Nevada jointfir	EPNE	Ephedra nevadensis	12–30	–
22				0–18
	Mojave rabbitbrush	ERPA29	Ericameria paniculata	0–18	–
23				6–18
	broom snakeweed	GUSA2	Gutierrezia sarothrae	6–18	–
24				6–18
	banana yucca	YUBA	Yucca baccata	6–18	–
25				6–12
	tulip pricklypear	OPPH	Opuntia phaeacantha	6–12	–
26				0–6
	Whipple cholla	CYWH	Cylindropuntia whipplei	0–6	–
27				6–12
	buckhorn cholla	CYACM	Cylindropuntia acanthocarpa var. major	6–12	–
28				0–12
	creosote bush	LATR2	Larrea tridentata	0–12	–
29				0–12
	water jacket	LYAN	Lycium andersonii	0–12	–
30				0–12
	desert willow	CHLI2	Chilopsis linearis	0–12	–

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	10/22/2024
Approved by	Kendra Moseley
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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