Ecological site F038XB229AZ

Tree	(1) Quercus
Shrub	(1) Fallugia paradoxa (2) Vitis arizonica
Herbaceous	(1) Muhlenbergia rigens (2) Elymus arizonicus

Landforms	(1) Flood plain
Flooding duration	Very brief (4 to 48 hours)
Flooding frequency	Occasional
Elevation	4000 – 5500 ft
Slope	1 – 5 %

Frost-free period (average)	180 days
Freeze-free period (average)	240 days
Precipitation total (average)	20 in

Surface texture	(1) Gravelly sandy loam
Family particle size	(1) Loamy
Drainage class	Well drained
Soil depth	40 – 60 in
Surface fragment cover <=3"	5 – 10 %
Surface fragment cover >3"	0 – 5 %
Available water capacity (0-40in)	2.5 – 5 in
Soil reaction (1:1 water) (0-40in)	6.6 – 7.8
Subsurface fragment volume <=3" (Depth not specified)	25 – 30 %
Subsurface fragment volume >3" (Depth not specified)	5 – 40 %

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

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Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference State Perennial Understory

2. Annual Understoy

State 1
Reference State Perennial Understory

At reference the ecological site has a mix of woody overstory, native perennial grasses, and forbs.

State 2
Annual Understoy

In state 2 the ecological site has crossed a threshold to a denser overstory, a loss of perennial grasses and dominant annual understory.

Transition T1
State 1 to 2

Continuous, season-long grazing, coupled with excessive utilization are the ecological drivers that create a state change.

Restoration pathway R1
State 2 to 1

Long-term grazing management incorporating monitoring of annual utilization, length of grazing period, and growth stage of plant during defoliation.

Additional community tables

Location 1: Graham County, AZ
Township/Range/Section	T1S R23E S11
General legal description	Rafter type location 2,600 feet north and 1,300 feet east of southwest corner of Section 11, Township 1 S, Range 23 E.

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

Ecological site F038XB229AZ

Sandy Bottom 16-20 (QUERC)

Last updated: 9/05/2019 Accessed: 09/13/2026

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General information

Figure 1. Mapped extent

MLRA notes

Ecological site concept

Table 1. Dominant plant species

Natural Resources
Conservation Service

Sandy Bottom
16-20
(QUERC)

Last updated: 9/05/2019
Accessed: 09/13/2026