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Ecological site F131AY501LA

Delta Plain - Frequently Flooded Ponded Very Poorly Drained Oxbows and Swales

Last updated: 6/10/2025
Accessed: 10/19/2025

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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.

MLRA notes

Major Land Resource Area (MLRA): 131A–Southern Mississippi River Alluvium

The Southern Mississippi River Alluvium (MLRA 131A) is the largest of 4 MLRAs within Land Resource Region O, the Mississippi Delta Cotton and Feed Grains Region. It occurs in portions of 7 states including Louisiana (32 percent), Arkansas (26 percent), Mississippi (26 percent), Missouri (12 percent), Tennessee (3 percent), Kentucky (1 percent), and Illinois (less than 1 percent). The MLRA is comprised of 29,555 square miles and extends roughly 650 miles from an area near Cape Girardeau, Missouri in the north to the MLRA’s transition to the Gulf Coast Marsh (MLRA 151) in the south. Average elevations range from 330 feet in the north to sea level in the southern part of the area. For much of the north-south distance, the MLRA is bounded to the east by an abrupt rise in elevation of loess-capped bluffs and hills, the Southern Mississippi Valley Loess (MLRA 134). West of the Mississippi River, the boundary is less distinct except to the northwest where the MLRA abuts the Ozark Plateaus and Ouachita province (MLRAs 116A, 117, and 118A). South of the Ozark and Ouachita escarpment, the MLRA adjoins the Southern Mississippi River Terraces (MLRA 131D), which includes the fabled Grand Prairie and merges with the valleys of the Arkansas and Ouachita rivers (MLRA 131B) and the Red River (MLRA 131C). Occurring within or bordering the Southern Mississippi River Alluvium are three separate loess-capped, upland remnants: Crowley’s Ridge, Macon Ridge, and Lafayette Loess Plain, which are western units of MLRA 134 (USDA-NRCS, 2006a).

MLRA 131A is characterized by landscapes that were created and influenced by the current and earlier paths of the Mississippi River and its tributaries. Waters transporting the materials that formed the area originate from as far west as the east slope of the Continental Divide to the western edge of the Appalachian Divide in the east. This comprises a drainage basin of roughly 1,245,000 square miles and includes all or parts of thirty-one U.S. states and two Canadian provinces (Elliott, 1932). The drainage basin of the Mississippi River roughly resembles a funnel which has its spout at the Gulf of America. Waters from as far east as New York and as far west as Montana contribute to flows in the lower extent of the river (USACE, 2017). The soils of these alluvial landscapes are very deep, dominantly poorly and somewhat poorly drained, and have textures that are mostly loamy or clayey. Principal soil orders are Alfisols, Vertisols, Inceptisols, and Entisols (USDA-NRCS, 2006a).

The fluvial processes that shaped the area were highly dynamic, diverse, and complex. During the Pleistocene epoch, multiple continental glacial-interglacial cycles resulted in extreme fluctuations in river discharge and sediment loads. A braided river regime characterized the fluvial dynamics of the Mississippi River through much of the last glacial cycle (Autin et al., 1991; Rittenhour et al., 2007). Rapid aggradation of glacial outwash led to the development of prominent valley train features over a large portion of the area (Autin et al., 1991; Saucier, 1994; Aslan and Autin, 1999; Blum et al., 2000; Rittenour et al., 2007). A changing climate, meltwater withdrawal, and sea-level change induced a transition from a braided river regime to a predominantly single-channeled, laterally migrating river system during the Holocene epoch (Rittenhour et al., 2007; Shen et al., 2012) – characteristics that continue today. Fluvial dynamics of the migrating river resulted in the development of broad meander belts, backswamp environments, and extensive deltaic complexes (Saucier, 1994; Klimas et al., 2011).

Tremendous expanses of bottomland hardwood forests once covered much of the area. Today, the land base is largely in agriculture production, and soybeans, cotton, corn, and rice are the principal crops with sugarcane rising in importance in the southernmost portion of the MLRA (USDA-NRCS, 2022).

Due to its size and biophysical variability, the technical team advised subdividing the MLRA into six subregions: Western Lowlands, St. Francis Basin, Yazoo Basin, Tensas Basin, Delta Plain, and Batture.

LRU notes

The Deltaic Plain of MLRA 131A is located in Louisiana, south of the Old River Control Structure on the Mississippi River. This portion of the MLRA is greatly affected by changes in hydrology over time, by both natural and anthropogenic forces. The landscape was built by the flooding of the Mississippi River with influences of the entire drainage basin.

The Mississippi River built the Deltaic Plain landscape through its multiple meandering channel belts and sediment deposition. The geologic development of coastal Louisiana is closely related to shifting Mississippi River courses. The Mississippi River Deltaic Plain developed as the Mississippi River changed its course multiple times throughout the Holocene Age. The Deltaic Plain is composed of six major delta complexes, two of which are prograding and four are degrading. Recognition that the Deltaic Plain is formed by an orderly progression of events related to shifting Mississippi River courses led to the identification and characterization of the deltaic cycle. The delta cycle is a dynamic and episodic process alternating between periods of seaward progradation of deltas (regressive deposition) and the subsequent landward retreat of deltaic headlands as deltas are abandoned, reworked, and submerged by marine waters (transgressive deposition) (USACE 2004). Within these shifts in land building and subsiding, the complexity of the ecological sites are realized. The interacting relationship between the alluvial landscape of MLRA 131A and the marsh landscape of MLRA 151 provides a gradual transition that obscures the boundary of these two regions. For the purposes of describing ecological sites, MLRA 131A sites are confined to those that are regarded as historically containing forested conditions and MLRA 151 sites confined to areas historically dominated by herbaceous marsh species. In addition to the interaction with MLRA 151 marshes, transitions from the Deltaic Plain into the adjacent MLRA 134 Southern Mississippi Valley Loess are abrupt in most places and are marked by loess covered plains to the east and west of the Deltaic Plain.

Classification relationships

Major Land Resource Area (MLRA) and Land Resource Unit (LRU) (USDA-NRCS, 2006) MLRA 131A Southern Mississippi River Alluvium

The Natural Communities of Louisiana - (Louisiana Natural Heritage Program - Louisiana Department of Wildlife and Fisheries)

EPA Level IV Ecoregion (73n - Inland Swamps, portions of 73k - Southern Holocene Meander Belts, and 73m Southern Backswamps)

Ecological site concept

This site contains wetland forests occurring on oxbow and swale positions in backswamps (depressional areas of floodplains between natural levees), which are frequently flooded and ponded for long periods. Soil inundation and saturation is a major driver on this site. These soils are deep to very deep, very poorly drained, slowly permeable, and formed in clayey alluvium on level or nearly level to concave slopes in the Southern Mississippi Valley Alluvium. Slopes range from 0 to 2 percent, with linear to concave-shaped slopes that create water-receiving, rather than water-shedding, landform positions that hold water for most of the year (except when artificially drained). This site is on floodplains in Level IV EPA Ecoregion 73n Inland Swamps, 73K Southern Holocene Meander Belts, and portions of 73m Southern Backswamps, of the Southern Mississippi River Alluvium Major Land Resource Area. Within the southernmost reach of the MLRA is the Deltaic Plain which extends from approximately where the Red River influence begins within the MLRA and to the south to near the gulf.

This site will cover a gradient from standing water to dry edges of ponded conditions. Over time the species gradient will change within the same location and may become colonized by less wet tolerant species. These changes occur for various reasons, including sedimentation of the depressions, reduced ponding if outlet is eroded, and reduced inflow of surface water as drainage patterns change. This site concept is the wettest on the local landscape and is often associated with standing water, however it may become very dry at times.

Of note, this site occurs on the “protected” side of the extensive Mississippi River levee system and is distinguished from similar landforms within the “batture lands” (i.e., the alluvial land between the river channel and the constructed levee system). Some locations of this site will receive Mississippi River flood waters at times within the Atchafalaya Floodway system; this is similar to the flooding that would have been received historically, however the frequency will be altered due to control structures and management.

Associated sites

F131AY502LA	Delta Plain - Poorly Drained Backswamp The Delta Plain - Poorly Drained Backswamp site will be found above this site and there will be a gradual transition between the sites.

F131AY502LA

Delta Plain - Poorly Drained Backswamp

The Delta Plain - Poorly Drained Backswamp site will be found above this site and there will be a gradual transition between the sites.

Similar sites

F131AY401LA	Tensas Basin - Frequently Flooded Ponded Very Poorly Drained Oxbows and Swales The Tensas Basin - Frequently Flooded Ponded Very Poorly Drained Oxbows and Swales is a similar site on a similar landscape position. The difference is the Tensas site is found north of the Red River in the Mississippi River Alluvium and this site is found to the south. At the provisional level there may be some need to utilize the Tensas Basin site description in the Northern extent of this site.

F131AY401LA

Tensas Basin - Frequently Flooded Ponded Very Poorly Drained Oxbows and Swales

The Tensas Basin - Frequently Flooded Ponded Very Poorly Drained Oxbows and Swales is a similar site on a similar landscape position. The difference is the Tensas site is found north of the Red River in the Mississippi River Alluvium and this site is found to the south. At the provisional level there may be some need to utilize the Tensas Basin site description in the Northern extent of this site.

Figure 1. 131AY501 ES Extent Map

Table 1. Dominant plant species

Tree	(1) Taxodium distichum (2) Nyssa aquatica
Shrub	(1) Cephalanthus occidentalis
Herbaceous	Not specified

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Physiographic features

This site occurs on backswamp and lower landscape positions where ponding is a regular occurrence.

Table 2. Representative physiographic features

Landforms	(1) Backswamp (2) Swale (3) Swamp (4) Flood plain
Runoff class	Very low to negligible
Flooding duration	Extremely brief (0.1 to 4 hours) to very long (more than 30 days)
Flooding frequency	Rare to very frequent
Ponding duration	Very brief (4 to 48 hours) to very long (more than 30 days)
Ponding frequency	None to frequent
Elevation	50 ft
Slope	2%
Ponding depth	2 in
Water table depth	24 in
Aspect	Aspect is not a significant factor

Climatic features

South Louisiana has a warm, humid climate, with fairly long summers and relatively short winters. The result is a long growing season and abundant plant growth. Water is a definitive part of the southern Louisiana landscape, largely due to the combination of low elevation and fairly abundant rainfall in most years. Mean annual precipitation ranges from 51 to 67 inches over this region and is fairly well distributed throughout the year. There have been very few years when less than 50 inches of precipitation has fallen. Snow is a rarity, and little more than 1 inch typically falls every few years. Growing seasons are long, typically from late February to late November. Along the gulf coast, it is not unusual for the lowest winter temperature to be above 30 degrees. Inland, there have been occasional blasts of cold air that have dropped temperatures into the teens and 20s, but these are rare. Hurricanes and tropical storms are an important part of the climate of southern Louisiana, with some impact occurring nearly every year in some part of the region. However, devastating storms do not occur too often, and heavy rain and storm surge are usually the biggest concerns, compared to wind damage. The following climatic data are averages from the weather stations listed below. Temperature and precipitation may vary considerably from that listed for each month. Site specific weather data should be used for land management decisions. For site specific weather conditions, obtain data from a weather station close to the site.

Information can be accessed from specific weather stations at http://www.wrcc.dri.edu/coopmap/ or http://www.wrcc.dri.edu/summary/climsmla.html.

Table 3. Representative climatic features

Frost-free period (characteristic range)	228-268 days
Freeze-free period (characteristic range)	272-365 days
Precipitation total (characteristic range)	59-64 in
Frost-free period (actual range)	222-304 days
Freeze-free period (actual range)	256-365 days
Precipitation total (actual range)	59-64 in
Frost-free period (average)	256 days
Freeze-free period (average)	336 days
Precipitation total (average)	62 in

Characteristic range

Actual range

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Figure 2. Monthly precipitation range

Characteristic range

Actual range

Bar

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Figure 3. Monthly minimum temperature range

Characteristic range

Actual range

Bar

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Figure 4. Monthly maximum temperature range

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Figure 5. Monthly average minimum and maximum temperature

Figure 6. Annual precipitation pattern

Figure 7. Annual average temperature pattern

Climate stations used

(1) CARVILLE 2 SW [USC00161565], Carville, LA
(2) LSU BEN-HUR FARM [USC00165620], Baton Rouge, LA
(3) MORGAN CITY [USC00166394], Berwick, LA
(4) RESERVE [USC00167767], Reserve, LA
(5) DONALDSONVILLE 4 SW [USC00162534], Donaldsonville, LA
(6) FRANKLIN 3 NW [USC00163313], Baldwin, LA
(7) BRUSLY 2 W [USC00161246], Brusly, LA
(8) JEANERETTE 5 NW [USC00164674], Jeanerette, LA
(9) ST BERNARD [USC00168108], Saint Bernard, LA
(10) ST MARTINVILLE 3 SW [USC00168181], Saint Martinville, LA
(11) BOOTHVILLE ASOS [USW00012884], Buras, LA
(12) HOUMA [USC00164407], Houma, LA
(13) LSU CITRUS RSCH STN [USC00165624], Port Sulphur, LA
(14) NEW ROADS 5 NE [USC00166686], Ventress, LA
(15) NEW ORLEANS AUDUBON [USW00012930], Marrero, LA

Influencing water features

This site is in a water-receiving position, generally the lowest on the local landscape. Flow may be received from adjacent landscapes at higher elevations, from upstream sources, and from backwater flooding events.

Wetland description

Cowardin System - Palustrine, Forested Wetland

Soil features

Please note that the soils listed in this section of the description may not be all inclusive. There may be additional soils that fit the site’s concepts. Additionally, the soils that provisionally form the concepts of this site may occur elsewhere, either within or outside of the MLRA and may or “may not” have the same geomorphic characteristics or support similar vegetation. Some soil map units and soil series included in this “provisional” ecological site were used as a “best fit” for a particular soil – landform catena during a specific era of soil mapping, regardless of the origin of parent material or the location of MLRA boundaries. Therefore, the listed soils may not be typical for MLRA 131A or a specific location, and the associated soil map units may warrant further investigation in a joint ecological site inventory – soil survey project. When utilizing this provisional description, the user is encouraged to verify that the area of interest meets the appropriate ecological site concepts by reviewing the soils, landform, vegetation, and physical location. If the site concepts do not match the attributes of the area of interest, please review the Similar or Associated Sites listed in the Supporting Information section of this description to determine if another site may be a better fit for your area of interest.

Barbary and Fausse are the modal soil series for this site. Other soil series include Harahan, Aquents, Dowling, Hydraquents, Maurepas, Schriever. These very deep, very poorly drained, and very slowly permeable soils formed in recent clayey alluvium and are almost continuously saturated due to flooding and ponding.

The Barbary (very-fine, smectitic, nonacid, hyperthermic Typic Hydraquents) soils formed in recent, slightly fluid to very fluid clayey sediments and are found on low, broad, ponded (undrained) backswamps. Barbary soils are continuously saturated with a water table that ranges from 12 inches above the surface to 6 inches below the surface. The Fausse (very-fine, smectitic, nonacid, hyperthermic Vertic Endoaquepts) soils also occur on low, ponded backswamps, but they remain constantly saturated in all layers below a depth of 24 inches.
Harahan (very-fine, smectitic, nonacid, hyperthermic Vertic Endoaquepts) soils formed in thick, firm clayey alluvium over fluid clayey sediments. These soils occur in artificially drained backswamps. Dowling (very-fine, smectitic, nonacid, thermic Vertic Endoaquepts) soils are the thermic equivalent of Fausse soils and occur mainly in low, ponded oxbow depressions and backswamps. Schriever (very-fine, smectitic, hyperthermic Chromic Epiaquerts) soils occur on the lower parts of natural levees and in backswamps; while the Schriever soils are saturated in the upper 6 inches during winter and spring, the soil profile dries out enough during the summer to form slickensides. Maurepas (Euic, hyperthermic Typic Haplosaprists) soils consist of organic soils that formed in woody plant remains mixed with a small amount of mineral soil matter, occur in the large backswamps of the lower Mississippi River Delta and some coastal areas.

Table 4. Representative soil features

Parent material	(1) Alluvium (2) Backswamp deposits (3) Woody organic material
Surface texture	(1) Clay (2) Silty clay (3) Mucky clay
Family particle size	(1) Clayey
Drainage class	Poorly drained to very poorly drained
Permeability class	Very slow
Soil depth	80 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (4-40in)	4 – 13.8 in
Calcium carbonate equivalent (0-40in)	3%
Electrical conductivity (0-40in)	1 mmhos/cm
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	5.3 – 7.5
Subsurface fragment volume <=3" (0-40in)	20%
Subsurface fragment volume >3" (0-40in)	Not specified

Ecological dynamics

Information contained in this section was adapted from several sources. The information presented is representative of very complex vegetation communities. Key indicator plants, animals, and ecological processes are described to help inform land management decisions. Plant communities will differ across the MLRA because of the naturally occurring variability in weather, soils, and hydrology. The reference plant community is not necessarily the management goal. The species lists are representative and are not botanical descriptions of all species occurring, or potentially occurring, on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the site.

This site is found in the Delta Basin of MLRA 131A which is in the Mississippi Alluvial Plain Section of the EPA Ecoregions in sub-sections 73n - Inland Swamps, portions of 73k - Southern Holocene Meander Belts and portions of 73m Southern Backswamps. The dissected plains in this portion of the MLRA have mixed soil minerology with influences from the majority of the Drainage Area of the Mississippi River.

The historic forests of this region once consisted entirely of bottomland hardwood deciduous forests, mixed hardwood, and cypress swamps. The major tree species in the native plant communities in the areas of bottomland hardwoods formerly were and currently are water oak, Nuttall oak, cherrybark oak, native pecan, red maple, sweetgum, eastern cottonwood, and hickory. The major tree species in the native plant communities in the swamps formerly were and currently are cypress, water tupelo, water oak, green ash, red maple, and black willow. The important native understory species are palmetto, greenbrier, wild grape, and poison ivy in the areas of bottomland hardwoods and buttonbush, lizard's tail, waterlily, water hyacinth, sedges, and rushes in the swamps. Land cover in many portions are now in farms, which produce mainly cash crops. Cotton, soybeans, milo, and corn are the main crops, and sugarcane is a major crop in the southernmost part of the area. Transitions from the Alluvial Plain into the adjacent Loess is abrupt in most places and is marked by Loess bluffs to the east and west of the MLRA.

The majority of the MLRA has been converted to agricultural production; minimal areas contain stands of historic plant communities, and many of these areas that have native vegetation has had significant hydrologic alteration. At the northern end of this sub-region of the MLRA, where the Red River, Atchafalaya River and Mississippi River converge are the Old River Control Structures. These structures are operated to maintain the distribution of flow between the Mississippi River and the Atchafalaya River, and also prevent the Atchafalaya River from capturing the flow of the Mississippi River. The Lower Atchafalaya Basin Floodway System is located within the bounds of this sub-region of the MLRA and includes six requirements: water management, recreation, public access, environmental protection, flood control, and water circulation/canal closure. The flood control component provides safety and livelihood protection to the surrounding communities; it limits the natural reach of the Mississippi River during overbank flow.

As mentioned previously this sub-region's northern extent is found at the Old River Control Structures which regulate the flows of the Mississippi, Red, and Atchafalaya Rivers. Additional components in the system are the river levee systems which further regulate the flows and flooding of these river systems. These constructed constraints to the system have substantially altered the hydrologic functions of the sites found within the whole of MLRA 131A. Unprotected areas within the confines of the levee systems have increased frequency, duration, depth, and force of flooding. Protected areas outside of the levee systems have reduced total flooding other than catastrophic events. These hydrologic alterations have changed ecological sites within the MLRA to where attempts at describing historic communities are best scientific concepts, so most sites are described based on current regimes. The current Atchafalaya River was initiated in the 18th century and by 1765 was well established and in 1831 the Shreve cutoff, near the location of the Old River Control Structure, minimized the flow between the Mississippi River and the Atchafalaya River. These natural and anthropogenic hydrologic impacts have occurred within the timeframe that is considered to define the Historic Community of the site, so the transitions between ecological states and other ecological sites are very dynamic.

This sub-region of the MLRA has its southernmost portion being positioned at the gulf and it is influenced by tidal forces. The Mississippi River built this landscape through its multiple meandering channel belts and sediment deposition. The geologic development of coastal Louisiana is closely related to shifting Mississippi River courses. The Mississippi River has changed its course several times during the last 7,000 years, leading to the development of the Mississippi River Deltaic and Chenier Plains. The Delta Plain is comprised of six major delta complexes, two of which are prograding and four are degrading. Recognition that the Delta Plain is formed by an orderly progression of events related to shifting Mississippi River courses led to the identification and characterization of the deltaic cycle. The delta cycle is a dynamic and episodic process alternating between periods of seaward progradation of deltas (regressive deposition) and the subsequent landward retreat of deltaic headlands as deltas are abandoned, reworked, and submerged by marine waters (transgressive deposition). Within these shifts in land building and subsiding the complexity of the ecological sites are realized, with transitions from the alluvial landscape of MLRA 131A to the marshes of MLRA 151. These close relationships and transitions between the alluvial landscape and the marsh landscape provides a gradual transition found in the southern most portion of the MLRA which is almost obscured. For the purposes of describing ecological sites, MLRA 131A sites are confined to those that are regarded as historically containing forested conditions and those that were historically dominated by herbaceous marsh species are considered MLRA 151 ecological sites.

This site is described as wetland forests occurring on oxbow and swale positions in backswamps, which are frequently flooded and ponded for long periods. Soil inundation and saturation is a major driver on this site as these soils are very deep, very poorly drained, slowly permeable clayey soils that rarely dry out. The level (0 to 2 percent), linear to concave-shaped slopes create water-receiving, rather than water-shedding, landform positions that hold water for most of the year (excepting artificial drainage).

This site will cover a gradient from standing water to dry edges of ponded conditions. Over time the species gradient will change within the same location and may become colonized by less wet tolerant species. These changes occur for various reasons, including sedimentation of the lows, reduced ponding if outlet is eroded, and reduced inflow of surface water as drainage patterns change. This site concept is the wettest on the landscape and is often associated with standing water, however it may become very dry at times.

Of note, this site occurs on the “protected” side of the extensive Mississippi River levee system and is distinguished from similar landforms within the “batture lands” (i.e., the alluvial land between the river channel and the constructed levee system). Some locations of this site will receive Mississippi River flood waters at times within the Atchafalaya Floodway system; this is similar to the flooding that would have been received historically, however the frequency will be altered due to control structures and management.

State and transition model

Custom diagram

Standard diagram

Figure 8. 131AY501 STM

Figure 9. 131AY501 STM Legend

More interactive model formats are also available. View Interactive Models

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

States 1, 5, 6 and 7 (additional transitions)

1. Historic Community Backswamp Hardwood

5. Converted State - Cropland

SWAPAEH

6. Converted State - Pasture or Grassland

7. Converted State - Urban development

States 3, 7 and 8 (additional transitions)

3. Open Water Sparse Trees

7. Converted State - Urban development

8. Converted State - Woody Encroached

SWAPAEH

T1A	-	Subsidence of soil surface or increased water depth.
T*-4	-	Catastrophic event river change in channel location to new run.
T1B	-	Build levees and install and maintain artificial drainage of site.
T1B	-	Build levees and install and maintain artificial drainage of site.
T1B	-	Build levees and install and maintain artificial drainage of site.
T2A	-	Sediment accumulation or reduced water depth.
T2B	-	Subsidence of soil surface or increased water depth.
T*-4	-	Catastrophic event river change in channel location to new run.
T3A	-	Sediment accumulation or reduced water depth.
T*-4	-	Catastrophic event river change in channel location to new run.
T4A	-	Channel change in path/ Reduced connection to main channel flow.
T5A	-	Loss or removal of levees and artificial drainage system.
T*-6	-	Establish desired forage species and manage for grazing.
T*-7	-	Build homes, roads, and other urban infrastructure.
T5A	-	Loss or removal of levees and artificial drainage system.
T*-5	-	Establish and manage crop rotation.
T*-7	-	Build homes, roads, and other urban infrastructure.
T6A	-	Lack of disturbance: Natural growth succession of woody species.
T5A	-	Loss or removal of levees and artificial drainage system.
T5A	-	Loss or removal of levees and artificial drainage system.

SWAPAEH

5.2. Transitional Conservation Management

SWAPAEH

5.3. Conventional Management

SWAPAEH

5.1A	-	Soil disturbance (Tillage) which reduces Soil Health.
5.1B	-	Conventional tillage, seeding, and fertility Management for crops.
5.2A	-	No-till, Cover crops, Reduced Till - Soil Health Improvements
5.2B	-	Conventional tillage, seeding, and fertility Management for crops.
5.3A	-	No-till, Cover crops, Reduced Till with Soil Health Improvements as a goal.

State 6 submodel, plant communities

6.1. Managed monoculture grassland

SWAPAEH

6.2. Mixed Species Managed System

SWAPAEH

6.3. Mixed Species, Non-seeded

SWAPAEH

6.4. Early Woody Succession

SWAPAEH

6.1A	-	Seeding and/or Management for desired species composition.
6.1B	-	Species Management without overseeding.
6.2A	-	Seeding and/or Management for desired species composition.
6.2B	-	Seeding and/or Management for desired species composition.
6.3A	-	Seeding, fertilizing, management/ removal of unwanted species.
6.3B	-	Seeding and/or Management for desired species composition.
6.3C	-	Lack of disturbance: No or minimal Mowing, burning, herbivory or Brush Mgmt. and/or Plant or natural regeneration of woody species.
6.4A	-	Brush management / removal of unwanted plants.

State 7 submodel, plant communities

7.1. Houses and Infrastructure

State 8 submodel, plant communities

8.1. Old field or planted hardwoods

SWAPAEH

State 1
Historic Community Backswamp Hardwood

Mixed Bottomland Hardwood - Baldcypress, Tupelo, Green Ash, Buttonbush

Community 1.1
Mixed Bottomland Hardwood

Figure 10. 131AY501-Ponded-Backswamp

Baldcypress, Tupelo, Green Ash, Buttonbush

State 2
Open Canopy

Open Canopy stand of cypress trees, marsh grasses, and open water.

Community 2.1
Open Canopy stand of cypress trees, marsh grasses, and open water.

Open Canopy stand of cypress trees, marsh grasses, and open water.

State 3
Open Water Sparse Trees

Open water - Sparse trees and sparse herbaceous vegetation.

Community 3.1
Open water - Sparse trees and sparse herbaceous vegetation

Sparse trees and sparse herbaceous vegetation.

State 4
New River Run & Floodplain

Catastrophic river change in channel (AVULSION) When the river changes courses, which is caused by multiple factors, this site will be affected in potentially many ways. This site may become the location of the new channel when the river re-occupies and older course or that of another river. Conversely when the river changes course and abandons previous backswamps the site may lose sediment and water inputs and become drier, which will allow the fluid sediments to consolidate.. This State potentially has more phases compared to all other Ecological Site states in this sub region.

Community 4.1
Catastrophic river change in channel (AVULSION)

When the river changes courses, which is caused by multiple factors, this site will be affected in potentially many ways. This site may become the location of the new channel when the river re-occupies an older course or that of another river. Conversely when the river changes course and abandons previous backswamps the site may lose sediment and water inputs and become drier, which will allow the fluid sediments to consolidate. This state potentially has more phases compared to all other ecological site states in this sub region.

State 5
Converted State - Cropland

This site is generally considered not suited for crop production due to flooding and wetness. When the site hydrology has been altered mechanically by the construction of levees, water control structures, and potentially pumps, crop species may be established, and the site utilized for production. Maintenance of the hydrologic control must be continued to maintain production and if control is abandoned or lost, site conditions may return to excessively wet conditions which will prevent utilization of the land for crop production. Conditions even with control may only allow production on an irregular basis. This state represents a crop production field. Annual plantings for forage production would also be included in this phase, which may include cool-season annual grasses and legumes and warm-season forage species. Vegetable crops are grown on this site and are generally on a small scale. Sugarcane, corn, and soybeans are dominant crops and can be planted in fields with adequate management. Wheat may be included in the rotation or as a standalone crop. Other row crop species have been produced on these sites. Often two or more crops will be grown in a multiyear rotation, this breaks pest cycles and some crops produce higher amounts of residue, which is left on the soil to improve soil health. Maintenance of monoculture crop stands also requires the control of unwanted species, which will require pest management and nutrient management to maintain the needed fertility for production of the desired species. Refer to E-Field Office Technical Guide (EFOTG) and the local NRCS Field Office for management assistance.

Dominant resource concerns

Sheet and rill erosion
Ephemeral gully erosion
Classic gully erosion
Bank erosion from streams, shorelines, or water conveyance channels
Subsidence
Compaction
Organic matter depletion
Aggregate instability
Nutrients transported to surface water
Nutrients transported to ground water
Pesticides transported to surface water
Pesticides transported to ground water
Plant productivity and health
Plant pest pressure

Community 5.1
Conservation Management

This cropland phase utilizes long term continuous conservation management systems including reduced till and cover crops, no-till with cover crops, and perennial cropping systems. Indicators of these systems take place in the soil and impacts how it functions; the state change can only be quantified using soil health indicator tests. The above-ground Crop growth is not the best tracking mechanism for this phase. Implementation of tillage even after long term no-till will reset the system back to conventional cropping systems, however returning to a conservation management system is achievable. There are instances where due to climatic conditions in a given crop year, tillage may be considered and/or needed to repair previous damage. These instances should be considered critically prior to implementing tillage if the desired outcome is aesthetics opposed to production. Critical conservation practices associated with this phase include Cover Crops, No-Till, and Reduced Till as the bedrock practices. There could also be associated supporting and site- specific practices that are needed to address specific conservation needs in a given management unit.

Community 5.2
Transitional Conservation Management

This cropland phase is a common scenario and could be in a continuous ‘transitional’ phase of conservation management state forever. Getting past years 1 and 2 will reduce the need to apply pesticides that call for bare soil for activation. Sugarcane is the most common perennial crop that would be a continuous transitional phase where intense tillage is implemented at the time of planting and then reduced tillage during the rotation. Planted forage crops could also be included in this phase when part of a crop rotation, as well as when part of a rotation where reduced tillage is implemented for one crop and then tillage is utilized for another crop in the rotation. Conservation practices are included with this phase and include nutrient management, pest management, reduced till, strip till and the inclusion of cover crops. There could also be associated supporting and site-specific practices that are needed to address specific conservation needs in a given management unit.

Dominant resource concerns

Sheet and rill erosion
Ephemeral gully erosion
Classic gully erosion
Subsidence
Compaction
Organic matter depletion

Community 5.3
Conventional Management

This cropland phase is typical conventional cropland where tillage is implemented as an annual part of the production system. When conventional annual tillage is part of the production system sugarcane is placed with conventional annual cropping. This system is productive and will require the utilization of conservation practices such as nutrient and pest management to address fertility needs and pest concerns within the crop production cycle. This phase may occur when tillage is implemented to address damage due to climatic conditions during a previous crop cycle in a conservation management system and the intention is to return to the conservation management system. There could also be associated, supporting, and site-specific practices that are needed to address specific conservation needs in a given management unit. Specific needs may include grade stabilization structures to control gully erosion, grassed waterways to trap sediment from sheet and rill erosion, or reduced till.

Dominant resource concerns

Sheet and rill erosion
Ephemeral gully erosion
Classic gully erosion
Subsidence
Compaction
Organic matter depletion
Sediment transported to surface water

Pathway 5.1A
Community 5.1 to 5.2

Soil disturbance (tillage) which reduces Soil Health.

Pathway 5.1B
Community 5.1 to 5.3

Conventional tillage, seeding, and fertility management for crops.

Pathway 5.2A
Community 5.2 to 5.1

Soil health Improvements - no-till, cover crops, reduced tillage. This transition will require soil health testing to determine reaching the conservation management phase and achieving this level of continuous soil health improvements.

Pathway 5.2B
Community 5.2 to 5.3

Conventional tillage, seeding, and fertility management for crops.

Pathway 5.3A
Community 5.3 to 5.2

Soil health improvements - no-till, cover crops, reduced tillage. This transition will require soil health testing to determine reaching the conservation management phase and achieving this level of continuous soil health improvements.

State 6
Converted State - Pasture or Grassland

This site is generally considered not suited for grazing due to flooding and wetness. When the site hydrology has been altered mechanically by the construction of levees, water control structures, and potentially pumps, forage species may be established, and the site utilized for grazing. Maintenance of the hydrologic control must be continued to maintain production and if control is abandoned or lost, site conditions may return to excessively wet conditions which will prevent utilization of the land for forage production. Conditions even with control may only allow forage production on an irregular basis. Additionally, adjacent higher elevation areas or protected areas may be needed for the storage of harvested forage or holding of livestock when wet or flooded conditions occur. Some forage operations on this site may experience none to multiple extreme wetness events in a single year that will require preplanning and resources to meet the needs of the livestock. This state is characterized by a monoculture or a mixture of forage species planted or allowed to establish from naturalized species managed for forage production or as herbaceous ground cover.

Community 6.1
Managed monoculture grassland

Typically, this phase is characterized by planting forage species for hay production. Forage plantings generally consist of a single grass species. Introduced native and/or non-native forage species can be seeded. Forage is usually harvested as hay or haylage, although grazing may occur periodically. These sites are highly productive for forage and can provide ecological benefits to control soil erosion. Allowing for adequate rest and regrowth of desired species is required to maintain productivity. Maintenance of monoculture stands also requires control of unwanted species which will require pest management and nutrient management to maintain the needed fertility for the production of the species. Generally, the application of fertilizer and lime is needed to establish and maintain improved desirable pastures. The exception to this is bahiagrass and common Bermudagrass, which can be sustained under natural fertility and pH levels. Introduced legumes require higher pH, phosphorus, and potassium levels than most grasses. Introduced grasses, such as hybrid bermudagrass, require a higher level of sustained fertility, maintain pH above 6.0, and good surface drainage, to persist. Implementation of prescribed grazing of grass species with a specific goal of growing roots deeper in the soil profile, in order to tap into the reservoir of available nutrients and moisture, to increase production, and sustain desirable forages. Conservation practices should include prescribed grazing, or forage harvest management, nutrient and pest management, and other site-specific facilitating practices.

Dominant resource concerns

Plant productivity and health
Plant structure and composition
Feed and forage imbalance

Community 6.2
Mixed Species Managed System

This community is characterized by mixed species composition of grasses and legumes, which is planted or naturally establishes. Typically, perennial warm-season grasses are the foundation of the stand which is periodically over seeded with adapted cool-season forages to extend the grazing season. This community phase can be highly productive for grazing and haying operations and can provide beneficial habitat for some wildlife species. Maintenance of grass stands also requires a collection of management practices such as prescribed grazing, brush management, pest management, and nutrient management to maintain the production of the desired species. Prescribed grazing includes maintaining proper grazing heights, timing, and stocking rates. Supporting or facilitating practices including fences, water lines, and watering facilities could be part of the system that maintains this phase.

Community 6.3
Mixed Species, Non-seeded

This community is characterized by a stand where mixtures of native and naturalized non-native species occur, this could also include abandonment of cropping (i.e., idle cropland that is not being utilized for forage production). This state represents low inputs after cropping, no initial seeding of pasture species or periodic over seeding of adapted forage species. Forage is usually grazed and/or harvested as stored forage, hay, or haylage. Common established species may include Bermudagrass, bahiagrass, Vasey’s grass, and carpet grass. This phase is productive, forage and grazing management can maintain forage stands and protect soils from excessive runoff and erosion. A common peril associated with this phase is overgrazing which favors less productive and less palatable weedy species, especially in areas where livestock congregate. Proper stocking rates and/or grazing systems that allow for adequate rest and plant regrowth are required to maintain productivity. When forage species are afforded adequate recovery time between grazing intervals, they will develop deeper root systems and greater leaf area allowing for the capture of greater solar energy, where photosynthesis fixes carbohydrates for plant growth. Conversely, when plants are not allowed to recover adequately, root development will be restricted, and forage and biomass production will be reduced. Maintenance of grass stands also requires pest management for control of unwanted weedy and woody species.

Community 6.4
Early Woody Succession

This community is characterized by a diverse species composition of grasses and forbs with an increasing composition of woody species (native and non-native) that are immature and low stature. If this community phase is not managed, and no brush management measures are taken, the plant community will transition to the Woody Encroached State (8). Control of woody species will require input of extensive resources to return to a Grassland or Cropland state. This phase is generally limited in woody species composition and size to the point where normal agricultural equipment is no longer able to return the site to a cropland phase, by mowing or disking. When the threshold is crossed to where the stem diameter exceeds 2 to 3 inches and the percent cover exceeds 100 to 300 stems per acre, the site has transitioned to the Woody Encroached State (8). If the restored hardwood community is desired, proper management is required. This phase can be a beneficial habitat for some wildlife species. Woody invasive species grow quickly and can be difficult and expensive to control. Some invasive woody species, such as tallow trees (Triadica sebifera), will invade and grow to produce seeds in as few as 3 years.

Dominant resource concerns

Sheet and rill erosion
Ephemeral gully erosion
Compaction
Feed and forage imbalance

Pathway 6.1A
Community 6.1 to 6.2

Seeding and/or management for desired species composition.

Pathway 6.1B
Community 6.1 to 6.3

Species management without overseeding.

Pathway 6.2A
Community 6.2 to 6.1

Seeding and/or management for desired species composition.

Pathway 6.2B
Community 6.2 to 6.3

Seeding and/or management for desired species composition.

Pathway 6.3A
Community 6.3 to 6.1

Seeding, fertilizing, management and removal of unwanted species.

Pathway 6.3B
Community 6.3 to 6.2

Seeding and/or management for desired species composition.

Pathway 6.3C
Community 6.3 to 6.4

Lack of disturbance: No or minimal mowing, burning, herbivory or brush management, and/or planted or natural regeneration of woody species.

Pathway 6.4A
Community 6.4 to 6.3

Brush management and/or removal of unwanted plants.

State 7
Converted State - Urban development

This site is generally considered not suited for urban development due to flooding and wetness. When the site hydrology has been altered mechanically by the construction of levees, water control structures and pumps development may be possible. Maintenance of the hydrologic control must be continued and if control is abandoned or lost, site conditions may return to excessively wet conditions which will inhibit urban development on this site. This state represents an area that has been altered to provide locations for homes, businesses, and infrastructure where people live, work, and recreate. The human population is higher than in the surrounding rural area. It is where buildings are close together and are usually considered cities and towns. This state may be found in small clusters in rural areas where multiple buildings are in close proximity with roads and infrastructure that support a rural population. The changes to the landscape will not generally return to the historic community of Hardwood trees, however, some of this landcover may be present in areas. There are generally many introduced species and potentially invasive species located in these areas and managed as ornamentals. These non-native species should be managed to prevent infestation and invasion into other areas where they can become a problem. Within this land use, there are expansive networks of infrastructure both above and below ground for use by the inhabitants of the area. These include roads, drainage channels and structures, electrical distribution systems, telecommunications systems, drinking water distribution systems, and many other components that contribute to the quality of human life.

Community 7.1
Houses and Infrastructure

This phase is described as homes, buildings, and infrastructure as part of an urban setting. This sub-region of the MLRA contains some fairly dense population centers, there are large cities, towns, and villages within this area. The idea of "concrete jungles" of large metropolitan centers is not typical for this phase, because many of the urbanized areas will include open spaces of semi-natural areas, gardens, and habitat for local wildlife. Areas that are typical for this site include recreational areas intermingled within the urban areas. These intermingled spaces will resemble and function very similar to other phases included within this site concept and should be referenced. This phase in this site is found where hydrology has been altered and is maintained to prevent flooding. It is common in the southern reaches of the MLRA where land area is reduced, and population density is higher. To describe this phase requires several potential types of vegetative communities as well as many surfaces that have been altered by excavation, deposition, and covering. The range of this state could be defined by many parameters, but for this purpose is maintained as a single broad phase. Many soil properties have been altered, hydrologic functions have been altered, and most of the vegetation within this phase is gardened and may not fit the norms of the site concept. The inclusion of this phase within this ecological site description is to acknowledge its presence and direct the users to qualified professionals for any work that is planned. The infrastructure within this state of the site will include pipelines, wires, and other potential hazards which will require contact of services to locate these to prevent damage if any soil disturbing activity is planned.

State 8
Converted State - Woody Encroached

Dominant resource concerns

Ephemeral gully erosion
Classic gully erosion
Subsidence
Compaction
Organic matter depletion
Concentration of salts or other chemicals
Plant productivity and health
Plant structure and composition

Community 8.1
Old field or planted hardwoods

This phase occurs when cropland or pastureland has been allowed to naturally regenerate without succession manipulation, or when hardwoods are planted on the site. This state will have succession very different from the Open Canopy phase of the historic community due to alterations in the site's hydrology. Species composition may be very different depending on the available seed source. When this occurs from a cropland or pasture state species composition may be dominated by introduced species, but desired hardwood species can be established to regenerate the state to that desired community.

Dominant resource concerns

Ephemeral gully erosion
Classic gully erosion
Subsidence
Compaction
Organic matter depletion
Concentration of salts or other chemicals
Plant productivity and health
Plant structure and composition

Transition T1A
State 1 to 2

Subsidence of soil surface or increased water depth.

Transition T*-4
State 1 to 4

Avulsion occurs when the river changes course to a new location. When this occurs, there are major changes to both locations on the landscape as well as the hydrologic regime. The transition will cause any given location to move into potentially any of the ecological site concepts which fit the sub-region of the MLRA.

Transition T1B
State 1 to 5

Build levees and install and maintain artificial drainage of site.

Transition T1B
State 1 to 6

Build levees and install and maintain artificial drainage of site.

Transition T1B
State 1 to 7

Build levees and install and maintain artificial drainage of site.

Transition T2A
State 2 to 1

Sediment accumulation or reduced water depth.

Transition T2B
State 2 to 3

Subsidence of soil surface or increased water depth.

Transition T*-4
State 2 to 4

Transition T3A
State 3 to 2

Sediment accumulation or reduced water depth.

Transition T*-4
State 3 to 4

Transition T4A
State 4 to 3

Channel change in path. Reduced connection to main channel flow. When a river channel is abandoned or reduced flow in the system, the Open Water Sparse Trees State begins to trap sediment and the transition pathway will turn towards the stable Backswamp Hardwoods state through the Open Canopy state.

Transition T5A
State 5 to 3

Loss or removal of levees and artificial drainage system.

Transition T*-6
State 5 to 6

Establish desired forage species and manage for grazing.

Transition T*-7
State 5 to 7

Build homes, roads, and other urban infrastructure.

Transition T5A
State 6 to 3

Loss or removal of levees and artificial drainage system.

Transition T*-5
State 6 to 5

Establish and manage crop rotation.

Transition T*-7
State 6 to 7

Build homes, roads, and other urban infrastructure.

Transition T6A
State 6 to 8

Lack of disturbance: Natural growth succession of woody species.

Transition T5A
State 7 to 3

Loss or removal of levees and artificial drainage system.

Transition T5A
State 8 to 3

Loss or removal of levees and artificial drainage system.

Additional community tables

Interpretations

Animal community

Hydrological functions

Recreational uses

Wood products

Woodland Suitability Groups - 2w6, 4w6, 5c0, 5d0, 5m0

Other products

Other information

Supporting information

Inventory data references

The information provided on the states and community phases in this provisional description report were generated from literature reviews, conversations with technical specialists, and limited personal observations and experience on this soil-site environment. Intensive vegetation inventories were not conducted during the development of this provisional report. Those tasks will occur during future phases of ecological site development.

References

Rogers, D.J. 2005. Evolution of the levee system along the Lower Mississippi River..
U. S. Army Corps of Engineers. 2004. Louisiana Coastal Area Comprehensive Coastwide Ecosystem Restoration Study. https://www.lca.gov/Library/ProductList.aspx?Prodtype=0&folder=1118. U.S. Army Corps of Engineers, New Orleans, LA, Online.

Other references

Aslan, A. and W.J. Autin. 1999. Evolution of the Holocene Mississippi River floodplain, Ferriday, Louisiana: Insights on the origin of fine-grained floodplains. Journal of Sedimentary Research 69: 800-815.

Aslan, A., W. J. Autin, and M. D. Blum. 2005. Causes of river avulsion: insights from the late Holocene avulsion history of the Mississippi River, USA. Journal of Sedimentary Research, 75(4), 650-664.

Autin, W.J., S.F. Burns, B.J. Miller, R.T. Saucier, and J.I. Snead. 1991. Quaternary geology of the Lower Mississippi Valley. p. 547-582. In R.B. Morrison (Editor). Quaternary Nonglacial Geology: Conterminous U.S. Geological Society of America. The Geology of North America, Volume K-2. Boulder, CO.

Autin, W. J. 1996. Pleistocene stratigraphy in the southern Lower Mississippi Valley. Engineering Geology, 45(1), 87-112.

Blum, M.D., M.J. Guccione, D.A. Wysocki, P.C. Robnett, and E.M. Rutledge. 2000. Late Pleistocene evolution of the lower Mississippi River valley, southern Missouri to Arkansas. Geological Society of America Bulletin, 112(2), 221-235.

Broadfoot, Walter M. 1976. Hardwood suitability for and properties of important midsouth soils. Res. Pap. SO-127. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 84 p.

Brown, D. A., V. E. Nash, A. G. Caldwell, L. J. Bartelli, R. C. Carter, and O. R. Carter. 1970. A monograph of the soils of the southern Mississippi River Valley alluvium. Southern Cooperative Series Bulletin, 178, 112.

Chapman, S.S, G.E. Griffith, J.M. Omernik, J.A. Comstock, Beiser, M.C., and D. Johnson. 2004. Ecoregions of Mississippi, (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,000,000).

Cowardin, L. M., V. Carter, F. C. Golet, and E. T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. US Fish and Wildlife Service FWS/OBS, 79(31), 131.

Cowdrey, A. E. 1977. Land’s End: A history of the New Orleans District. US Army Corps of Engineers, and Its Lifelong Battle with the Lower Mississippi and Other Rivers Wending Their Way to the Sea.

Daigle, J.J., G.E. Griffith, J.M. Omernik, P.L. Faulkner, R.P. McCulloh, et al. 2006. Ecoregions of Louisiana (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,000,000).

Ezell, A.W. 2016. Evaluating high-graded hardwood stands. Publication-Cooperative Extension Service, Mississippi State University (USA).

Fisk, H. N. 1944. Geological investigation of the alluvial valley of the lower Mississippi River: US Dept. Army, Mississippi River Comm.

Foti, T., C. Klimas, J. Pagan, and A. Keister. 2011. Potential natural vegetation of the Mississippi Alluvial Valley: Tensas Basin, Northeastern Louisiana. U.S. Fish and Wildlife Service, Lower Mississippi Valley Joint Venture; Vicksburg, MS.

Gardiner, E. S., and J. M. Oliver. 2005. Restoration of bottomland hardwood forests in Lower Mississippi Aluvial Valey, USA. In: Stanturf, JA; Madsen, P. eds. Restoration of boreal and temperate forests. Restoration of bottomland hardwood forests in the Lower Mississippi Alluvial Valley, USA Boca Raton, FL: CRC Press. 235-251.

Grigar, J., J.L. Hatfield, and R. Reeder, 2018. Transitional no-till: What is it and how does it differ from ‘true’no-till?. Crops and Soils 51, no. 6:28–36.

Kemp, K. 2000. The Mississippi Levee System and the Old River Control Structure. Available online: http://www.tulane.edu/~bfleury/envirobio/enviroweb/FloodControl.htm. Accessed 11/2018

Klimas, C.V. 1988. Forest vegetation of the leveed floodplain of the lower Mississippi River. Lower Mississippi River Environmental Program Report 11. US Army Corps of Engineers. Vicksburg, Mississippi.

Klimas, C., J. Pagan, T. Foti, and B. Tirpak. 2011. Potential natural vegetation of the Mississippi Alluvial Valley: Yazoo Basin, Mississippi. U.S. Fish and Wildlife Service, Lower Mississippi Valley Joint Venture; Vicksburg, MS.

Lentz, G. H. 1928. Summary of First Year's Hardwood Investigations in Louisiana. US Forest Service and Louisiana Division of Forestry
Lentz, G. H. 1929. Summary of First Year's Hardwood Investigations in Louisiana. Journal of Forestry, 27(5), 486-494.

McKnight, J.S., D.D. Hook, O.G. Langdon, and R.L. Johnson. 1981. Flood tolerance and related characteristics of trees of the bottomland forests of the southern United States. In Developments in Agricultural and Managed Forest Ecology. 11, pp. 29-69. Elsevier. https://www.srs.fs.usda.gov/pubs/ja/1980/ja_1980_mcknight_001.pdf (accessed 12 Oct. 2018)

Putnam, J. A., and H. Bull. 1932. The trees of the bottomlands of the Mississippi River Delta Region. US Department of Agriculture, Forest Service, Southern Forest Experiment Station, Occasional Paper, 27, 207.

Rittenhour, T.M., M.D. Blum, and R.J. Goble. 2007. Fluvial evolution of the Lower Mississippi River Valley during the last 100 k.y. glacial cycle: Response to glaciation and sea-level change. Geological Society of America Bulletin 119(5-6): 586-608.

Rogers, D. 2005. Evolution of the levee system along the Lower Mississippi River. University of Missouri-Rolla: Rolla, MO, USA. https://web.mst.edu/~rogersda/levees/Evolution%20of%20the%20Levee%20System%20Along%20the%20Mississippi.pdf. Accessed 10/2018.

Saucier, R. T. 1974. Quaternary geology of the lower Mississippi Valley (No. 6). Arkansas Archeological Survey.

Saucier, Roger T. 1994. Geomorphology and Quaternary Geologic History of the Lower Mississippi Valley, Volumes I & II. U.S. Army Corps of Engineers, Vicksburg, MS. (Available online: http://biotech.law.lsu.edu/climate/mississippi/sausier/sausier.htm)

Schumm, S. A., and W. J. Spitz. 1996. Geological influences on the Lower Mississippi River and its alluvial valley. Engineering Geology, 45(1-4), 245-261.

Shen, Z., T.E. Tornqvist, W.J. Autin, Z.R.P. Mateo, K.M. Straub, and B. Mauz. 2012. Rapid and widespread response of the Lower Mississippi River to eustatic forcing during the last glacial-interglacial cycle. Geological Society of America Bulletin 124(5-6): 690-704.

Theriot, R. F. 1992. Flood tolerance of plant species in bottomland forests of the southeastern United States. Ph.D. diss. University of Florida. Available online: http://ufdc.ufl.edu//AA00003281/00001

Turner, S., J. Welch, and N. Musso. 2010. The Atchafalaya National Heritage Area, Selected Level 0 Cultural Landscape Assessments. Suzanne Turner Associates LLC. Available online: http://www.atchafalaya.org/ckfinder/userfiles/files/CLA-Final.pdf

Tye, R. S., and J. M. Coleman. 1989. Depositional processes and stratigraphy of fluvially dominated lacustrine deltas: Mississippi delta plain. Journal of Sedimentary Research, 59(6).

[USACE] U.S. Army Corps of Engineers. 2004. Louisiana Coastal Area Comprehensive Coastwide Ecosystem Restoration Study. U.S. Army Corps of Engineers, New Orleans, LA. Available online: https://www.lca.gov/Library/ProductList.aspx?Prodtype=0&folder=1118.

[USACE] U.S. Army Corps of Engineers New Orleans District, Missions, Mississippi River Flood Control. No date. [Online]. Retrieved June 30, 2017. Available at http://www.mvn.usace.army.mil/Missions/Mississippi-River-Flood-Control/

[USACE] U.S. Army Corps of Engineers. Atchafalaya Basin Project, Brochure, http://www.mvn.usace.army.mil/Portals/56/docs/PAO/Brochures/AtchafalayaBasinProject.PDF (accessed 12 Oct. 2018)

[USDA-NRCS] United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. US Department of Agriculture Handbook, 296.

[USDA, SCS] USDA, Soil Conservation Service. 1968. Soil Survey Interpretations for Woodland in the Southern Mississippi Valley Alluvium Area of LA MS AR TN MO and KY, Progress Report.

[USDA-NRCS] United States Department of Agriculture, Natural Resources Conservation Service. 2022. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture, Agriculture Handbook 296.

Contributors

D. Charles Stemmans II
Rachel Stout-Evans
Brandon Waltman
Mitchel Mouton

Approval

Charles Stemmans, 6/10/2025

Acknowledgments

I would like to acknowledge the MLRA 131A Technical Team for their support and assistance in drafting this site concept and Provisional Ecological Site Description.

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	06/10/2025
Approved by	Charles Stemmans
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

Click on box and path labels to scroll to the respective text.

States 1, 5, 6 and 7 (additional transitions)

1. Historic Community Backswamp Hardwood

5. Converted State - Cropland

SWAPAEH

6. Converted State - Pasture or Grassland

7. Converted State - Urban development

States 3, 7 and 8 (additional transitions)

3. Open Water Sparse Trees

7. Converted State - Urban development

8. Converted State - Woody Encroached

SWAPAEH

T1A	-	Subsidence of soil surface or increased water depth.
T*-4	-	Catastrophic event river change in channel location to new run.
T1B	-	Build levees and install and maintain artificial drainage of site.
T1B	-	Build levees and install and maintain artificial drainage of site.
T1B	-	Build levees and install and maintain artificial drainage of site.
T2A	-	Sediment accumulation or reduced water depth.
T2B	-	Subsidence of soil surface or increased water depth.
T*-4	-	Catastrophic event river change in channel location to new run.
T3A	-	Sediment accumulation or reduced water depth.
T*-4	-	Catastrophic event river change in channel location to new run.
T4A	-	Channel change in path/ Reduced connection to main channel flow.
T5A	-	Loss or removal of levees and artificial drainage system.
T*-6	-	Establish desired forage species and manage for grazing.
T*-7	-	Build homes, roads, and other urban infrastructure.
T5A	-	Loss or removal of levees and artificial drainage system.
T*-5	-	Establish and manage crop rotation.
T*-7	-	Build homes, roads, and other urban infrastructure.
T6A	-	Lack of disturbance: Natural growth succession of woody species.
T5A	-	Loss or removal of levees and artificial drainage system.
T5A	-	Loss or removal of levees and artificial drainage system.

State 1 submodel, plant communities

1.1. Mixed Bottomland Hardwood

State 2 submodel, plant communities

2.1. Open Canopy stand of cypress trees, marsh grasses, and open water.

State 3 submodel, plant communities

3.1. Open water - Sparse trees and sparse herbaceous vegetation

State 4 submodel, plant communities

4.1. Catastrophic river change in channel (AVULSION)

State 5 submodel, plant communities

5.1. Conservation Management

SWAPAEH

5.2. Transitional Conservation Management

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5.3. Conventional Management

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5.1A	-	Soil disturbance (Tillage) which reduces Soil Health.
5.1B	-	Conventional tillage, seeding, and fertility Management for crops.
5.2A	-	No-till, Cover crops, Reduced Till - Soil Health Improvements
5.2B	-	Conventional tillage, seeding, and fertility Management for crops.
5.3A	-	No-till, Cover crops, Reduced Till with Soil Health Improvements as a goal.

State 6 submodel, plant communities

6.1. Managed monoculture grassland

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6.2. Mixed Species Managed System

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6.3. Mixed Species, Non-seeded

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6.4. Early Woody Succession

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6.1A	-	Seeding and/or Management for desired species composition.
6.1B	-	Species Management without overseeding.
6.2A	-	Seeding and/or Management for desired species composition.
6.2B	-	Seeding and/or Management for desired species composition.
6.3A	-	Seeding, fertilizing, management/ removal of unwanted species.
6.3B	-	Seeding and/or Management for desired species composition.
6.3C	-	Lack of disturbance: No or minimal Mowing, burning, herbivory or Brush Mgmt. and/or Plant or natural regeneration of woody species.
6.4A	-	Brush management / removal of unwanted plants.

State 7 submodel, plant communities

7.1. Houses and Infrastructure

State 8 submodel, plant communities

8.1. Old field or planted hardwoods

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Natural ResourcesConservation Service

Ecological site F131AY501LA

Delta Plain - Frequently Flooded Ponded Very Poorly Drained Oxbows and Swales

Last updated: 6/10/2025 Accessed: 10/19/2025

General information

MLRA notes

LRU notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Figure 1. 131AY501 ES Extent Map

Table 1. Dominant plant species

Ecosystem states

States 1, 5, 6 and 7 (additional transitions)

States 3, 7 and 8 (additional transitions)

Natural Resources
Conservation Service

Last updated: 6/10/2025
Accessed: 10/19/2025