Ecological site F040XC327AZ

F040XC328AZ	Loamy Bottom, Woodland 3"-7" p.z. adjacent stream terrace, no visible soil redox features
R040XC318AZ	Sandy Wash 3"-7" p.z. large water courses with ephemeral flow, no visible soil redox features

R040XA125AZ	Sandy Bottom, Woodland 10"-13" p.z. Elevations 2,000' - 3,200', precipitation zone 10
F040XB215AZ	Sandy Bottom, Woodland 7" - 10" p.z. Elevations 1,200' - 2,000', precipitation zone 7

Tree	(1) Populus fremontii (2) Salix gooddingii
Shrub	(1) Pluchea sericea
Herbaceous	Not specified

Frost-free period (average)	300 days
Freeze-free period (average)	350 days
Precipitation total (average)	10 in

Surface texture	(1) Loamy sand
Family particle size	(1) Sandy
Drainage class	Somewhat poorly drained to somewhat excessively drained
Permeability class	Moderately rapid to rapid
Soil depth	40 – 60 in
Available water capacity (0-40in)	0 – 2.5 in

Ecological dynamics

The plant community on this site is dominated by tall trees, primarily cottonwood and willow, with a diverse understory of tree seedlings, perennial and annual grasses and forbs, and some shrubs. State 1, Native Riparian Woodland, rarely occurs given the pervasive extent of non-native trees and shrubs in the MLRA. State 2, Non-Native Mixed Woodland, has saltcedar and other non-native species present within the native community, though non-natives are not dominant. State 3, Dense Non-Native Woodland, is a dense, near monoculture of saltcedar. Natural fire is not common in State 1, however, State 2 and State 3 have the potential to accumulate sufficient fuels to carry a fire. When fire does occur, high heat intensity can radiate outward, killing cactus (saguaro and cholla) growing up to 100 yards away from the narrow river channel.

State and transition model

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State 1
Native Riparian Woodland

Figure 3. Native Riparian Woodland State

Sandy Bottom Woodland, 3"-7" p.z., is a cottonwood-willow dominated riparian gallery woodland. Perennial surface water occurs in long reaches, with sufficient flow to sustain native obligate wetland plants. Flash floods regularly occur, resulting in overbank flow and bank scour. Cottonwood and willow seeds germinate on wet sands along the braided watercourses, and seedlings quickly establish before water levels return to normal. Natural fire is not a regular occurrence, as indicated by old-growth cactus, like saguaro, growing adjacent to the site. Saguaro are extremely sensitive to heat from burning.

Community 1.1
Cottonwood-Willow

Cottonwood and willow dominate the plant community, with an understory of seep willow and arrowweed. The herbaceous understory of annual and perennial forbs fluctuates with the seasons. Wetland obligate species are present where surface or near surface water is available.

State 2
Non-native Mixed Woodland

Non-native Mixed Woodland is similar in function and composition to Native Riparian. Saltcedar and other non-natives (such as tree tobacco, bermudagrass, and cocklebur) are intermixed with native species. Native tree recruitment can be affected by a reduction of flash flooding events, lowering of the water table, or saltcedar competition.

Community 2.1
Cottonwood-Saltcedar

Cottonwood-willow-saltcedar community is a dense woodland with understory thickets of arrowweed. Non-native species present include saltcedar, tree tobacco, and bermudagrass.

State 3
Dense Non-Native Woodland

Figure 4. State 3 showing decadence of saltcedar dominated community

Figure 5. Saltcedar dominated community 1 yr post-burn; fire ignition from welding pipeline on extremely dry and windy day.

The Dense, Non-native Woodland State is a near monoculture of saltcedar.

Community 3.1
Saltcedar

Several Tamarix species are represented in this MLRA; saltcedar (T. ramosissima) is the species that most commonly forms monoculture communities.

Transition T1A
State 1 to 2

Native Riparian Woodland

Non-native Mixed Woodland

Non-native species introduction by various mechanisms including animal transport, wind, and flooding.

Transition T2A
State 2 to 3

Non-native Mixed Woodland

Dense Non-Native Woodland

Transition processes can include fire, channel-scouring flooding, or disturbance of normal flooding regime.

Restoration pathway R3A
State 3 to 2

Dense Non-Native Woodland

Non-native Mixed Woodland

Return of shallow water table and flash flooding events, pole planting, brush management, or prescribed grazing.

Additional community tables

Table 5. Community 1.1 plant community composition

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

Table 6. Community 2.1 plant community composition

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

Table 7. Community 3.1 plant community composition

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

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	07/15/2026
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 F040XC327AZ

Sandy Bottom, Woodland 3"-7" p.z.

Last updated: 10/17/2024 Accessed: 07/15/2026

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General information

MLRA notes

LRU notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Natural Resources
Conservation Service

Sandy Bottom, Woodland
3"-7" p.z.

Last updated: 10/17/2024
Accessed: 07/15/2026