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Ecological site F131AY206AR

St. Francis - Wet Braided Interfluve Forest

Last updated: 6/10/2025
Accessed: 08/21/2026

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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., 2011a).

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

There are no agency-approved and established Land Resource Units (LRUs) for MLRA 131A. However, the characteristics of each of the six subregions in this MLRA warrant noting and are presented here for each associated ecological site. This provisional ecological site is mapped within the St. Francis Basin.

The St. Francis Basin is geographically positioned in northeastern Arkansas and southeastern Missouri where it, in addition to the Batture and Western Lowlands, form the northern terminus of MLRA 131A. For convenience and ease of administering the Ecological Site Inventory, small portions of the MLRA occurring east of the Mississippi River in extreme western Tennessee and Kentucky are collectively grouped with the basin’s extent in Arkansas and Missouri. The following characterization includes the combined area.

The MLRA boundary of the basin extends some 190 miles (north to south) from Cape Girardeau, Missouri to the vicinity of Helena, Arkansas. For much of its north-south distance, its width (east to west) is approximately 40 miles but narrows considerably south of Memphis, TN. The basin is bounded to the west by Crowley’s Ridge and to the east by the most recent meander belt of the Mississippi River. Elevations range from about 340 feet in the north to around 175 feet in the south (Saucier, 1994). St. Francis Basin includes portions of: Lee, St. Francis, Crittendon, Cross, Poinsett, and Mississippi counties of Arkansas; Pemiscot, Dunkin, New Madrid, and Mississippi counties of Missouri; Lake, Dyer, and Lauderdale counties of Tennessee. Major towns include: West Memphis, Marked Tree, Trumann, Blytheville, Paragould, Piggott, and Black Oak, Arkansas; Caruthersville, Hayti, Portageville, Kennett, Charleston, Sikeston, and Cape Girardeau, Missouri; and Tiptonville, Tennessee. Major highways include: Interstate 55, Interstate 40, U.S. Highway 61, U.S. Highway 63, U.S. Highway 64, U.S. Highway 78, and TN Highway 103.

The geomorphology of the basin is exceedingly complex – manifestations of incredible hydrogeologic and geologic forces. The most significant of these forces for the Mississippi River Valley was serving as a sluiceway through which huge quantities of glacial meltwater and outwash were funneled during multiple continental glaciations. The northwestern two thirds of the basin is mainly comprised of Late Pleistocene (ca. 11,700 to 129,000 years B.P.; chronology after Head, 2019) glacial outwash materials. Large landscapes or “basin subareas” were created or influenced by tremendous amounts of outwash material that, episodically, were released during catastrophic outburst floods of enormous magnitude (Saucier, 1994). Fluvial dynamics of these events resulted in braided river regimes of both the Mississippi and Ohio rivers. Examples of large landscapes that were shaped and reshaped by these fluvial processes and episodes include Sikeston Ridge, Charleston Fan, Morehouse Lowland, and Malden Plain (Stevens and Krusekopf, 2020). Major geomorphic features created in the wake of these forces include prominent sandy ridges; broad, braided-stream terraces (valley trains) at varying elevations or levels; and eolian environments of sand dune fields east of Sikeston Ridge (Saucier, 1994).

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 (ca. 11,700 years B.P. to present; epoch chronology after Head, 2019) (Rittenour et al., 2007; Shen et al., 2012). Landscapes across the southeastern third of the St. Francis Basin are mainly comprised of former paths of the Mississippi River and its associated alluvial environment of sinuous meander belts. Major landforms comprising the meander belt environment include natural levees, point bar deposits (meander scrolls) and abandoned channels (oxbow lakes) and courses. The higher elevations of natural levees and point bars form an alluvial ridge, which often directs local drainage and floodwaters to the intervening flood basins or backswamps (Saucier, 1994).

In addition to hydrologic influences, the basin’s landscapes are subject to geologic forces. In 1811-1812, four of the largest earthquakes to hit eastern North America occurred in an area that encompassed extreme northeastern Arkansas, southeastern Missouri, and northwestern Tennessee. This area is known as the New Madrid Seismic Zone, which is named after a small settlement near the epicenter of one of the earthquakes (Saucier, 1994). Reports of the New Madrid earthquakes included widespread bank caving, reversal of river flow, landslides, earth waves, forest destruction, land uplifts, and land sinking. A few of the notable land areas or features attributed to or influenced by the seismic events include the St. Francis Sunken Lands, Tiptonville Dome, Ridgely Ridge, Reelfoot Lake, and massive landslides occurring along the adjoining Loess Bluffs of MLRA 134 (Fuller, 1912; Saucier, 1994). Perhaps the most dramatic geomorphic effects were the land fissuring and sand blows resulting from liquefaction (Saucier, 1994). According to Castilla and Audemard (2007), these are “…the largest ever-reported isolated sand blows.” Saucier (1994) emphasized that there are millions of liquefaction features from the earthquakes that are distributed over a 4,000 square mile area.

The movement of water through the basin is influenced by the complex sequence of remnant braided outwash channels, overflow channels, distributaries, and former channels and courses of the Mississippi River. Many of these features convey smaller modern streams within them. Principal streams of the basin are its namesake, the St. Francis River in addition to Little River, Tyronza River, and Pemiscot Bayou. Historically, large floods on the Mississippi River and in the St. Francis tributary system and greater basin led to frequent flooding, inundating landscapes of low relief for very long durations (Moore, 1972). To lessen the severity of flooding, the St. Francis Basin underwent a coordinated and comprehensive flood control and drainage effort. Extensive modification of the basin’s natural hydrology included hundreds of miles of constructed levees along the mainstem of the Mississippi River and basin tributaries; channel modifications on many streams; constructed floodways; water control structures; land leveled areas; and an extensive network of surface drainage systems (Klimas et al., 2013). The extensive modifications to the basin’s hydrology coupled with increased access set the stage for broadscale conversion of former forestland to a variety of land uses with agriculture production being dominant.

All ecological sites in the St. Francis Basin are bounded by the extensive constructed levee system along the Mississippi River. The constructed levee occurs on both sides (i.e., east and west) of the active river channel. The areas protected by levees east of the Mississippi River include portions of Lake, Obion, Dyer, and northern Lauderdale counties in Tennessee and the western extent of Fulton County, Kentucky. (Soils mapped in southern Illinois’s portion of MLRA 131A mostly have a mesic soil temperature regime and do not correlate to this ecological site.) All lands between the river channel and the constructed levee (or Loess Hills where levees are absent) are referred to as the Batture, and that subregion encapsulates its own complement of ecological sites due to significantly different hydrologic regimes (Smith and Klimas, 2002).

Classification relationships

All or portions of the geographic range of this site fall within several ecological and land classifications including:
- NRCS Major Land Resource Area (MLRA) 131A – Southern Mississippi River Alluvium (USDA-NRCS, 2006a)
- National Hierarchical Framework of Ecological Units: 234 Lower Mississippi Riverine Forest Province; 234D White and Black River Alluvial Plains Section; 234Da North Mississippi River Alluvial Plain Subsection (Cleland et al., 2007)
- Environmental Protection Agency Level III Ecoregion: 8.5.2 Mississippi Alluvial Plain, 73; Level IV Ecoregion: Northern Pleistocene Valley Trains, 73b; St. Francis Lowlands, 73c (Griffith et al., 1998; Chapman et al., 2002; Woods et al., 2002; Woods et al., 2004; Wiken et al., 2011)
- The following is the HGM Subclass, geomorphic setting, and PNV association that best correlates to this site in the St. Francis Basin (developed by Klimas et al., 2013): F7, Poorly drained undulating topography on Pleistocene outwash terraces, Willow Oak - Water Oak; RB5, Occasionally flooded Pleistocene deposits, Willow Oak - Nuttall Oak

Ecological site concept

The Wet Braided Interfluve Forest is widely distributed on interfluves among the remnant glacial outwash channels on Late Pleistocene valley train terraces. This site generally occupies positions that are adjacent to or adjoin the lower, Braided Channel Forest ecological site. The soils are very deep, somewhat poorly to poorly drained that formed in loamy alluvium. Slopes are typically 0 to 3 percent but may range up to 8 percent, locally. Seasonal high water tables are typically present during winter through spring. Species occurring on this site may include willow oak (Quercus phellos), Nuttall oak (Q. texana), water oak (Q. nigra), swamp chestnut oak (Q. michauxii), sweetgum (Liquidambar styraciflua), green ash (Fraxinus pennsylvanica), American elm (Ulmus americana), and sugarberry (Celtis laevigata) with cherrybark oak (Q. pagoda) occurring on drier locations. Pin oak (Q. palustris) may increase in importance in northern portions of this site.

The species listed in Table 1 were derived from literature reviews and conversations with technical specialists. One or more of the species listed may not be dominant or present at a given location, and opinions may differ as to the dominant or representative species of this ecological site. Extreme caution should be exercised when developing or inferring conservation decisions, actions, or determinations based on Table 1, alone. A more complete listing of species anticipated on this site, including species targeted for their conservation value, can be found in the Ecological Dynamics section of this report.

Associated sites

F131AY204AR	St. Francis - Braid Bar Woodland This site is representative of remnant sandy braid bars and is the highest feature on Late Pleistocene valley train terraces. In many areas, it adjoins the lower and wetter poorly to somewhat poorly drained interfluves of F131AY206AR.
F131AY207AR	St. Francis - Braided Channel Forest The poorly drained soils of this site are representative of the remnant braided outwash channels of Late Pleistocene valley train terraces. It broadly adjoins the poorly to somewhat poorly drained interfluves of F131AY206AR.
F131AY205AR	St. Francis - Loamy Braided Interfluve Forest The loamy soils of this site occur on higher interfluves of Late Pleistocene valley trains. It adjoins the lower and wetter poorly to somewhat poorly drained interfluves of F131AY206AR.

F131AY204AR

St. Francis - Braid Bar Woodland

This site is representative of remnant sandy braid bars and is the highest feature on Late Pleistocene valley train terraces. In many areas, it adjoins the lower and wetter poorly to somewhat poorly drained interfluves of F131AY206AR.

F131AY207AR

St. Francis - Braided Channel Forest

The poorly drained soils of this site are representative of the remnant braided outwash channels of Late Pleistocene valley train terraces. It broadly adjoins the poorly to somewhat poorly drained interfluves of F131AY206AR.

F131AY205AR

St. Francis - Loamy Braided Interfluve Forest

The loamy soils of this site occur on higher interfluves of Late Pleistocene valley trains. It adjoins the lower and wetter poorly to somewhat poorly drained interfluves of F131AY206AR.

Similar sites

F131AY210AR	St. Francis - Old Moderately Wet Natural Levee and Meander Scroll Forest This site primarily occurs on abandoned natural levees and meander scroll ridges of former paths of the Mississippi River. Many of the same somewhat poorly drained soils of F131AY210AR have been delineated on the braided interfluves of F131AY206AR.
F131AY110AR	Western Lowlands - Old Moderately Wet Natural Levee and Braided Interfluve Forest This site developed under similar conditions, has similar soils and drainage characteristics, and occurs on similar geomorphic features as site F131AY206AR. The principal difference is that F131AY110AR occurs in the Western Lowlands.
F131AY211AR	St. Francis - Old Wet Natural Levee and Meander Scroll Forest This site primarily occurs on the toeslopes of abandoned natural levees and meander scroll swales of former paths of the Mississippi River. Many of the same poorly drained soils of F131AY211AR have been delineated on the braided interfluves of F131AY206AR.

F131AY210AR

St. Francis - Old Moderately Wet Natural Levee and Meander Scroll Forest

This site primarily occurs on abandoned natural levees and meander scroll ridges of former paths of the Mississippi River. Many of the same somewhat poorly drained soils of F131AY210AR have been delineated on the braided interfluves of F131AY206AR.

F131AY110AR

Western Lowlands - Old Moderately Wet Natural Levee and Braided Interfluve Forest

This site developed under similar conditions, has similar soils and drainage characteristics, and occurs on similar geomorphic features as site F131AY206AR. The principal difference is that F131AY110AR occurs in the Western Lowlands.

F131AY211AR

St. Francis - Old Wet Natural Levee and Meander Scroll Forest

This site primarily occurs on the toeslopes of abandoned natural levees and meander scroll swales of former paths of the Mississippi River. Many of the same poorly drained soils of F131AY211AR have been delineated on the braided interfluves of F131AY206AR.

Figure 1. Distribution of F131AY206AR.

Table 2. Dominant plant species

Tree	(1) Liquidambar styraciflua (2) Quercus phellos
Shrub	(1) Ilex decidua
Herbaceous	(1) Carex

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Physiographic features

This ecological site occupies the lower elevations of braided interfluves on Late Pleistocene valley train (braided stream terrace) landscapes. It is intermediate in elevation between the higher and drier loamy interfluves (F131AY205AR) and the lower and wetter, remnant braided outwash channels (F131AY207AR). The characteristic surface feature of this site consists of level to nearly level treads and subtle rises that developed when vast volumes of coarse-grained glacial outwash were transported and deposited by an extensive network of braided river channels (Saucier, 1994). The coarse-grained outwash materials were subsequently heavily veneered with Holocene silty and loamy alluvium.

Of note, the poorly to somewhat poorly soils of this site have been mapped on other geomorphic features such as old natural levees and meander scrolls of the Mississippi River and its tributaries (F131AY210AR and F131AY211AR).

Block diagram illustrating the Pleistocene terraces in association with the St. Francis River. Dundee soils are representative of wet interfluves (this site).

Figure 1. Block diagram illustrating the Pleistocene terraces in association with the St. Francis River. Dundee soils are representative of wet interfluves (this site).

Figure 2. Block diagram of the braided terraces in Missouri. Dundee soils are representative of wet interfluves (this site).

Table 3. Representative physiographic features

Landforms	(1) Alluvial plain remnant > Valley train
Runoff class	Negligible to low
Flooding duration	Brief (2 to 7 days)
Flooding frequency	None to occasional
Ponding frequency	None
Elevation	210 – 330 ft
Slope	0 – 2 %
Water table depth	9 – 33 in
Aspect	Aspect is not a significant factor

Climatic features

Climate of the St. Francis Basin is classified as Humid Subtropical (Koppen System), which is typified by mostly cool to mild winters; long, hot and humid summers; and no routinely recurring wet or dry season (Klimas et al., 2011b). The average annual air temperature from 1980 through 2010 was 60 degrees F and the mean annual precipitation for the same period was 49 inches.

In the warmer season (and throughout much of the year), winds from the south convey moisture from the Gulf of America leading to humid, semitropical conditions that are favorable for convective thunderstorms. These storms produce a significant proportion of the area’s annual precipitation and are at times accompanied by locally destructive winds. A potential hazard during late summer through early fall is the tropical cyclone. While most impacts from hurricanes and tropical storms are confined along the coastal zone, heavy rainfall, severe flooding, and high winds can occur well into the basin when such systems pass through the area. To the extreme, the region is susceptible to the effects of a strong Bermuda High during the summer, which can cause devastating drought conditions for weeks and even months in some years. Typically, August and September are the driest months of the year with an average monthly low at or less than 2.8 inches.

In the colder season, the area’s weather is dominated by the positions of the Polar and Subtropical Jet Streams, both of which exert strong control over the passages of cold and warm fronts. These fronts alternately bring cold continental air and warm tropical air with periods of varying length. Particularly strong cold fronts can produce large and sudden drops in air temperature; however, cold spells seldom last over a week. The coldest month of the year is typically January with an average monthly low and high of 24 and 47 degrees, respectively. The frost-free period from 1980 to 2010 averaged 181 days basin-wide and ranged from 162 days in the northernmost extent to 193 days in the south. Likewise, the freeze-free period averaged 215 days and ranged from 192 days in the north to 223 days in the southern part of the basin.

Snow and/or sleet falls in the area in most years with the greatest frequency and accumulations occurring in the northern extent. Winter precipitation sometimes occurs as freezing rain and damaging ice storms hit some portion of the basin on occasion. However, these wintry events are generally the exception; they are typically brief and do not persist for very long. Rain is the characteristic form of winter precipitation, and the period of greatest rainfall generally occurs from November through July with April and May being the months of highest averages.

Table 4 Representative climatic features

Frost-free period (characteristic range)	180-190 days
Freeze-free period (characteristic range)	210-220 days
Precipitation total (characteristic range)	50-50 in
Frost-free period (actual range)	170-190 days
Freeze-free period (actual range)	200-220 days
Precipitation total (actual range)	50-50 in
Frost-free period (average)	180 days
Freeze-free period (average)	220 days
Precipitation total (average)	50 in

Characteristic range

Actual range

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Figure 3. Monthly precipitation range

Characteristic range

Actual range

Bar

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Figure 4. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 5. Monthly maximum temperature range

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Figure 6. Monthly average minimum and maximum temperature

Figure 7. Annual precipitation pattern

Figure 8 Annual average temperature pattern

Climate stations used

(1) ADVANCE 1 S [USW00093825], Advance, MO
(2) CHARLESTON [USC00231540], Charleston, MO
(3) SIKESTON PWR STN [USC00237772], Sikeston, MO
(4) NEW MADRID [USC00236045], Hickman, MO
(5) MALDEN MUNI AP [USC00235207], Malden, MO
(6) PORTAGEVILLE [USC00236804], Portageville, MO
(7) KENNETT RADIO KBOA [USC00234417], Kennett, MO
(8) CARUTHERSVILLE [USC00231364], Caruthersville, MO
(9) PARAGOULD 1S [USC00035563], Paragould, AR
(10) BLYTHEVILLE MUNI AP [USW00053869], Blytheville, AR
(11) KEISER [USC00033821], Keiser, AR
(12) WEST MEMPHIS MUNI AP [USW00053959], Marion, AR

Influencing water features

This site is representative of the lowest and wettest interfluves among the remnant braided channels of the Late Pleistocene outwash terraces. This site receives runoff from higher geomorphic features, and where it adjoins active stream systems, it is subjected to flooding. The location or position of some soils may be high enough in elevation that hydric conditions are not supported. However, some soils, particularly the poorly drained and problematic somewhat poorly drained soils (e.g., Commerce and Dundee soils), may support hydric indicators. In some locations, this site may be heavily influenced by local hydrologic regimes and wetland obligate and facultative wetland plants may be supported. Caution should be exercised when attempting offsite wetland determinations.

Wetland description

Under the Cowardin et al. (1979) system, this site is classified as:<br />
System: Palustrine<br />
Class: Forested Wetland<br />
Subclass: Broad-leaved Deciduous

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 this description to determine if another site may be a better fit for your area of interest.

This site is characterized by very deep, poorly to somewhat poorly drained soils that formed in silty and loamy alluvium. Slopes are generally within 0 to 3 percent but may range up to 8 percent, locally. Soils provisionally correlated to this site consist of an eclectic mix of textures and drainage characteristics and include the Commerce, Convent, Dundee, Fountain, Patterson, Routon, Tunica, and Waverly series.

The Commerce (fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquepts) series consists of somewhat poorly drained soils that formed in loamy alluvium. Solum thickness ranges from 20 to more than 80 inches. Where drainage is natural, aquic conditions occur within 20 inches of the surface, and the soils are saturated in layers below 1.5 to 4 feet from December through April in most years. Permeability is moderately slow, and there is 18 to 35 percent clay in the 10-to 40-inch control section. In some pedons, clayey strata (Bssg or Bg horizon) may occur below 50 inches and function as an aquitard, although saturated layers generally occur beneath the strata. Reaction ranges from medium acid to moderately alkaline in the upper layers, slightly acid to moderately alkaline in the cambic (Bw) horizons, and neutral to moderately alkaline in all underlying layers. Slopes range from 0 to 5 percent.

The Convent (coarse-silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquepts) series consists of somewhat poorly drained soils that formed in recent loamy alluvium. Solum thickness ranges from 6 to 60 inches. The soil is saturated in all layers below depths of 1.5 to 4 feet from December through June in normal years. It stays saturated within a depth of 20 inches for periods of up to 1 month duration in normal years. Reaction ranges from moderately acid to moderately alkaline throughout. Many pedons have carbonates in some strata below a depth of 20 inches. Slopes range from 0 to 3 percent.

The dominant soils of this site are the Dundee (fine-silty, mixed, active, thermic Typic Endoaqualfs) series. The site’s core concepts and spatial distribution are based largely on the characteristics and mapped distribution of these soils. Dundee soils formed in thinly statified beds of loamy alluvium. Permeability is described as moderately slow. Soil reaction is dominantly very strongly acid to moderately acid but can range to slightly alkaline in the C horizon of some pedons. Base saturation by sum of cations for Dundee is quite high, ranging from 62 to 80 percent at depths of 50 inches below the upper boundary of the B horizon, a strong indicator of the soil's fertility. Relatedly, the calcium-magnesium ratio is greater than 1. Under natural drainage conditions, an apparent water table occurs 1.5 to 3.5 feet below the surface during the winter and spring months in most years. In areas that are intentionally drained, the water table ranges from 3.5 to 6 feet below the surface. Slopes range from 0 to 8 percent.

The Fountain (fine-silty, mixed, superactive, thermic Typic Glossaqualfs) series consists of poorly drained soils that have moderately slow permeability. These soils formed in silty deposits of Late Pleistocene age and have many characteristics of loess. The A horizon ranges from 6 to 15 inches thick with reactions that range from medium acid through mildly alkaline. Tongues of the A horizon, 1 to 6 inches wide, extend to a depth of 20 to 40 inches below the surface. The upper 20 inches of the Bt horizon averages between 18 and 30 percent clay and 3 to 10 percent sand that is dominantly very fine sand. The Bt horizon ranges from neutral to moderately alkaline, and most pedons have carbonate concretions within the middle or lower Bt horizon. A silt loam B3 horizon is present in most pedons and has reactions ranging from neutral to moderately alkaline. The C horizon is silt loam and has reactions that range from neutral to moderately alkaline. An apparent water table is at the surface to 1.5 feet below the surface from December through April in most years. Slopes range from 0 to 1 percent. These soils are of minor extent and appear to have been predominantly mapped on Late Pleistocene terraces that either received loess deposits or were heavily influenced by water reworked loess.

The Patterson (fine-loamy, mixed, active, thermic Typic Endoaqualfs) series consists of somewhat poorly drained, moderately permeable soils that formed in loamy sediments. Solum thickness ranges from 50 to more than 70 inches. Combined thickness of the A and E horizons is more than 20 inches with a texture of sandy loam, fine sandy loam, or loamy fine sand. The Bt horizon ranges from 18 to 30 inches thick with a texture of fine sandy loam, sandy clay loam or clay loam. The BC horizon ranges from 0 to 15 inches thick with a texture that is sandy loam or fine sandy loam. The C horizon has a texture that is sandy loam, fine sandy loam, loamy fine sand, or fine sand. Reaction ranges from very strongly acid to slightly acid in the A horizon; very strongly acid or strongly acid in the E, B, and BC horizons; and ranges from very strongly acid to neutral in the C horizon. A seasonal water table is within 1 to 2 feet of the soil surface in late winter and spring. Slopes are dominantly less than 1 percent, but they range from 0 to 2 percent. Patterson soils are primarily mapped on nearly level to depressional low terraces (usually adjacent to or in association of eolian dunes and dunefields) in the Western Lowlands of northeast Arkansas and southeast Missouri. Their distribution in the St. Francis Basin is of minor extent.

The Routon (fine-silty, mixed, active, thermic Typic Epiaqualfs) series consists of poorly drained, slowly permeable soils that formed in loess or silty alluvium derived from loess greater than 4 feet thick. Thickness of solum ranges from 40 to greater than 65 inches. Diagnostic features of some pedons include an albic horizon (Eg) 7 to 14 inches thick; argillic horizon (Btg) 16 to 30 inches thick; aquic conditions consisting of saturation, reduction, and redoximorphic features 0 to 54 inches (Ap, Eg, Btg, BCg horizons); and episaturation in the layers above 54 inches during periods when the layer below 54 inches is not saturated (Ap, Eg, Btg, BCg horizons). The A, E and Bt horizons range from slightly acid to very strongly acid and the BC and C horizons range from neutral to strongly acid. Slopes range from 0 to 3 percent. Routon soils occur on broad, level to nearly level terraces and upland divides of the Southern Mississippi Valley Loess (MLRA 134) where they often form or occur on prominent depressions in association with the surrounding level landscape. The only instance of these soils occurring outside of the thick loess belt of MLRA 134 is the Mississippi County, Arkansas soil survey area. Those delineations warrant field investigation.

The Tunica (clayey over loamy, smectitic over mixed, superactive, nonacid, thermic Vertic Epiaquepts) series consists of poorly drained soils that formed in clayey and the underlying loamy alluvium. Tunica soils have vertic properties of slickensides in the upper clayey subsoil. Depth to the contrasting loamy discontinuity ranges from 20 to 36 inches from the surface. Clay content above the discontinuity ranges from 35 to 75 percent and 10 to 32 percent below the discontinuity. They are saturated in the surface layer and along cracks and slickenside faces in the subsoil during December through April in most years. Reaction ranges from moderately acid to slightly alkaline in the clayey upper layers and subsoil and moderately acid to moderately alkaline in the underlying loamy layers. Slopes are dominantly 0 to 3 percent but range to 5 percent on narrow ridges within the flood plain. Tunica soils are generally mapped on transitional areas between natural levees and backswamps. They are mapped in low-lying positions of this site where floodwaters are prone to entrapment.

The Waverly (coarse-silty, mixed, active, acid, thermic Fluvaquentic Endoaquepts) series consists of poorly drained soils that have moderate permeability. They formed in silty alluvium derived mainly from loess of low sand content. The 10- to 40-inch control section has 5 to 18 percent clay. These poorly drained soils have aquic conditions consisting of saturation, reduction, and redoximorphic features including a gleyed matrix between 5 and 30 inches deep (Bg1, Bg2, Bg3 horizons). Brown and black concretions are few to many throughout the solum. Areas in depressions are ponded during wet seasons, often for very long durations. The water table is at or within one foot of the surface during the winter and spring months in most years, and these soils are subject to occasional or frequent flooding for brief to long duration after heavy rainfall. Reaction is very strongly acid or strongly acid throughout. Slope gradients are mainly less than 1 percent but range to 2 percent, locally. Waverly soils primarily occur on floodplains of streams that drain the Southern Mississippi Valley Loess (MLRA 134) but may also occur on alluvial fans along the edge of the Loess Hills. These soils are of minor extent on this ecological site.

Additional soils may be added to this site as new and updated information suggest their inclusion is warranted. Conversely, some provisional soil components may be transferred to a different site during subsequent phases of ecological site development.

Table 5. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Fine sandy loam (2) Silt loam (3) Silty clay (4) Very fine sandy loam
Drainage class	Poorly drained to somewhat poorly drained
Permeability class	Very slow to rapid
Soil depth	80 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (Depth not specified)	6.7 – 8.6 in
Calcium carbonate equivalent (Depth not specified)	Not specified
Electrical conductivity (Depth not specified)	0 – 1 mmhos/cm
Sodium adsorption ratio (Depth not specified)	Not specified
Soil reaction (1:1 water) (Depth not specified)	5.3 – 7.3
Subsurface fragment volume <=3" (40in)	1 – 3 %
Subsurface fragment volume >3" (40in)	Not specified

Ecological dynamics

Historically, this ecological site was part of a vast forested landscape with processes and functions directly connected to the highly dynamic nature of the Mississippi River (Gardiner and Oliver, 2005). Widespread changes to the landscape occurred long before any intensive studies of the historic natural communities were conducted. Accordingly, reference conditions of this ecological site are still under review. Although knowledge and interpretation of reference conditions are currently incomplete, observations and forest research over the past century have provided information on species presence, suitability, and productivity of important forest resources on some soils of this site. Their presence, management, and sustainability form the basis of the “perceived” reference state for the site.

Putnam (1951) described his “sweetgum – water oaks” forest type as occurring on multiple geomorphic features throughout the Southern Mississippi River Alluvium. Landscape conditions that he characterized as supporting the type (and resembling the features of this site) include “…pervious silty clays on terrace flats” and “…poorly drained flats on terraces.” Important or key species comprising the type include sweetgum, water oak, Nuttall oak, willow oak, American elm, sugarberry, and green ash. Additional forest associates consist of overcup oak, pecan, water hickory, cedar elm, eastern cottonwood, red maple, honeylocust (Gleditsia triacanthos), and common persimmon (Putnam, 1951). Putnam indicated that variations of the sweetgum – water oaks type were commonplace with variants comprised predominantly of either sweetgum, water oaks (i.e., Nuttall, willow, water, and overcup), or a third variant, the cedar elm – water oaks forest type. Putnam’s sweetgum – water oaks type was later absorbed into more broadly accepted forest types such as the sweetgum – willow oak type (Society of American Foresters, SAF, Type No. 92; Eyre, 1980) or simply renamed the sweetgum – red oak species association (see Hodges,1997; Meadows and Stanturf, 1997). Based on Putnam’s description alone, it is construed that the same or very similar cover type and forest components occur on this site in the St. Francis Basin with possible modifications in the northern portions of the basin.

The forest type predicted for this site (per Putnam) was independently corroborated by colleagues in Missouri during early ecological site efforts in that state. They described a sweetgum – willow oak association as the dominant type occurring on nearly level, wet braided stream terraces and floodplains (see Community 1.1). Dominant species of this community reportedly include willow oak, sweetgum, pin oak, Nuttall oak, water oak, American elm, sugarberry, and green ash. Canopy heights were estimated to range from 70 to 90 feet with cover estimates of 80 to 100 percent closure. The understory was described as relatively open with a diverse ground flora. Sedges (Carex spp.) were a dominant herbaceous component, although patches of bare ground were interspersed in lower, wetter areas.

It is hypothesized that the lower positions of this site historically flooded yearly or in most years. Most flooding may have occurred from the ponding of rainfall and sheet flow across the landscape. The historic flood regime likely occurred from late fall into spring with a duration of a couple of months (Doug Wallace, personal communication).

To the south in Arkansas, Klimas et al. (2013) described similar forest components as occurring on occasionally flooded interfluve areas of Pleistocene terraces. The characteristic association consisted of a willow oak – Nuttall oak community with additional dominants of Delta or bottomland post oak (Quercus similis) and water oak. Community associates included cherrybark oak, green ash, American elm, and sweetgum.

One important characteristic that has been repeatedly stressed by forest authorities is the transition of the sweetgum – willow oak (or “water oaks”) type to a sugarberry – American elm – green ash association (SAF Type No. 93; Eyre, 1980) following major disturbances such as heavy cutting or repeated partial harvests (Putnam and Bull, 1932; Putnam, 1951; Hodges, 1997; Oliver et al., 2005). Today, the prevailing association occurring on this ecological site may be the sugarberry – American elm – green ash forest association or a variant of this type given the intensive landuse histories most areas have incurred. Eyre (1980) provides a general description of the sugarberry – American elm – green ash type and several components listed above are associates of that type including species that are highly favored in management on this ecological site, such as Nuttall oak, willow oak, water oak, sweetgum, and green ash. (An expanded list of trees favored in management is included in the narrative of State 1 of the State and Transition Model, below.) However, Oliver et al. (2005) warns that red oaks (e.g., cherrybark, willow, water, and Nuttall) are not regrowing in sufficient concentrations to sustain their former densities, which could have consequences on other factors such as wildlife and commercial timber values. Much of these concerns are founded on forest composition transitioning to a more shade-tolerant community such as the sugarberry – American elm – green ash type. Hodges (1997) emphasized that the latter is long-lived and capable of self-replacement.

Overall, forest cover on this site is minor compared to other uses. Most areas have been cleared and are used extensively for row crop production. Some areas have been land leveled with soil surface cuts of up to 3 feet to meet irrigation needs. A secondary use on this site is pasturage.

Following this narrative, a “provisional” state and transition model is provided that includes the “perceived” reference state and several alternative (or altered) vegetation states that have been observed and/or projected for this ecological site. This model is based on limited inventories, literature, expert knowledge, and interpretations. Plant communities may differ from one location to the next depending on the severity of local land use activities and rates of deposition. Depending on objectives, the reference plant community may not necessarily be the management goal.

The environmental and biological characteristics of this site are complex and dynamic. As such, the following diagram suggests pathways that the vegetation on this site might take, given that the modal concepts of climate and soils are met within an area of interest. Specific locations with unique soils and disturbance histories may have alternate pathways that are not represented in the model. This information is intended to show the possibilities within a given set of circumstances and represents the initial steps toward developing a defensible description and model. The model and associated information are subject to change as knowledge increases and new information is garnered. This is an iterative process. Most importantly, local and/or state professional guidance should always be sought before pursuing a treatment scenario.

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

T1A	-	Manipulate composition and manage for production (Community 2.1); Heavy timber cutting/high-grading (Community 2.2)
T1B	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T1C	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T2A	-	Reestablish missing species; control exotics (mechanical/chemical); timber stand improvement; natural stand dynamics
T2B	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T2C	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T3A	-	Precision land leveling
T3B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T3C	-	Natural succession (Community 6.1) or site prep (plow pan breakup, fertilizing, etc.); planting species appropriate for site (Community 6.2)
T3D	-	Establish select native species suitable for site; prep site for planting (herbicide and/or mechanical)
T5A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T5B	-	Natural succession (Community 6.1) or site prep (plow pan breakup, fertilizing, etc.); planting species appropriate for site (Community 6.2)
T5C	-	Establish select native species suitable for site; prep site for planting (herbicide and/or mechanical)
T6A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T6B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T7A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T7B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T7C	-	Natural succession (Community 6.1) or site prep (plow pan breakup, fertilizing, etc.); planting species appropriate for site (Afforestation - Community 6.2)

State 1 submodel, plant communities

1.1. Sweetgum – Willow Oak Wet Braided Interfluve Forest

State 2 submodel, plant communities

2.1. Forest Management

2.2. Non-managed/High-graded

2.1A	-	Cessation of management followed by heavy cutting/repeated partial harvests
2.2A	-	Silvicultural treatments: removal of undesirable species; re-establish species favored in management; timber stand improvement; establish advance regeneration

State 3 submodel, plant communities

3.1. Conservation Management

3.2. Transitional Conservation Management

3.3. Conventional Management

3.1A	-	Soil disturbance (tillage); reduction of soil health.
3.1B	-	Conventional tillage, seeding, and fertility management for crops.
3.2A	-	No-till, cover crops, reduced till–soil health improvements.
3.2B	-	Conventional tillage, seeding, and fertility management for crops.
3.3A	-	Reduced till, no-till, and cover crops with soil health improvements as a goal.

State 4 submodel, plant communities

4.1. Land Leveled Cropland

State 5 submodel, plant communities

5.1. Monoculture Grassland

5.2. Mixed Species System

5.3. Mixed Species, Non-seeded

5.4. Early Woody Succession

5.1A	-	Seeding and/or management for desired species composition.
5.1B	-	Species management without overseeding.
5.2A	-	Seeding, fertilizing, management/removal of undesirable species.
5.2B	-	Species management without overseeding
5.3A	-	Seeding, fertilizing, management/removal of undesirable species.
5.3B	-	Seeding and/or management for desired species composition.
5.3C	-	Lack of disturbance; no (infrequent) mowing, herbivory, or brush management; natural succession of woody species.
5.4A	-	Brush management/removal of unwanted species.

State 6 submodel, plant communities

6.1. Ruderal/Opportunistic Regrowth

6.2. Afforestation

6.1A	-	Remove undesirable competitors; final soil preparation; establish site-appropriate species (favored in management).

State 7 submodel, plant communities

7.1. Pollinator Planting/Native Grasses

State 1
Reference: Wet Interfluve Forest

Removal of or extensive modification to the historic natural communities in the St. Francis Basin occurred long before thorough studies and investigations were conducted. Furthermore, drainage patterns and surface characteristics of the landscape have since been heavily altered. Great variability is likely to occur throughout the distribution of most if not all ecological sites. Local soils and hydrologic regimes will have been influenced by the environment they occur within including former land use histories. Such complexity across the area will likely result in much variability in vegetation composition and structure of local environments (Stanturf et al., 2001).

Accordingly, reference conditions for this site have yet to be confirmed, but recent observations and published accounts have provided a convincing context from which to guide future efforts. Once assigned or identified and verified, the reference community will not represent the pre-settlement forest community, but it should identify an assemblage of naturally occurring species that reflects and contributes to regional biodiversity and local ecological dynamics. Implicated in the latter is that the “local” geomorphic features and drainage patterns of this soil-site environment should not have been drastically altered or removed (e.g., land leveled).

The name of this state (currently assigned the Reference State and warrants verification) is an interpretation based on observations by Missouri colleagues and bolstered by Klimas et al. (2013). The poorly to somewhat poorly drained soils of this site have broad extent across the surfaces of the Late Pleistocene valley trains in southeastern Missouri and northeastern Arkansas. Observations and literature accounts published to date are combined, herein.

The current state and transition model does not have a return or transition pathway from the altered states back to reference conditions. Former land uses (alternate states) that result in altered soil structure (e.g., compaction and increased bulk densities), lower soil organic matter content, altered fertility, and smaller available rooting volume can reduce woodland site productivity by 10 to 20 percent for some species(Groninger et al., 1999) and may result in high seedling mortality. Attempts to establish reference conditions under these soil-site constraints could result in poor establishment and response, colonization by undesirable taxa, or failure. These soil-site impacts, however, can be ameliorated through various “afforestation” techniques such as plow pan breakup (subsoil or deep plowing), fertilization, and fallowing fields before stand establishment (Emile Gardiner, USFS Research Forester, personal communication). State 6 (Forest Recovery) is representative of forest establishment and growth on locations where soil compaction and reduction of nutrients have occurred. Once a previously affected location has recovered its site potential, transition to the reference state may be possible. Realistically, it may not always be possible to return to a “perceived” reference state from a former altered condition. While planting and establishing trees appropriate for a site may be possible, achieving restoration of the understory and other system functions present challenges that may never be realized (Stanturf et al., 2001; Flinn and Vellend, 2005). That potential transition is still under review and is currently not shown or addressed in the state and transition model.

Community 1.1
Sweetgum – Willow Oak Wet Braided Interfluve Forest

Based on available information, this community is “provisionally” considered to be representative of reference conditions for this ecological site. This community was recognized by Putnam (1951) as the sweetgum – water oaks type and later refined into a singular forest type: sweetgum – willow oak (Eyre, 1980). During early ecological site inventories, colleagues in Missouri described the “wet braided terrace” soils as dominantly supporting a sweetgum – willow oak / possumhaw (Ilex decidua) / sedge (Carex spp.) – pale touch-me-not (Impatiens pallida) forest association (Doug Wallace, personal communication). Independent investigations conducted by Klimas et al. (2013) in Arkansas reported similar dominant canopy species occurring on occasionally flooded, wetter interfluves of Pleistocene outwash terraces.

Dominant canopy species reported on this site in Missouri and Arkansas include willow oak, sweetgum, pin oak, water oak, Nuttall oak, American elm, sugarberry, and green ash (Klimas et al., 2013; Doug Wallace, personal communication). Associates of varying abundance patterns may include Delta or bottomland post oak and cherrybark oak in drier areas. Eyre (1980) provided an expanded list of possible associates of this cover type including overcup oak (Q. lyrata), pecan (Carya illinoinensis), water hickory (C. aquatica), cedar elm (Ulmus crassifolia), eastern cottonwood (Populus deltoides), red maple (Acer rubrum), honeylocust (Gleditsia triacanthos), and persimmon (Diospyros virginiana). Understory components may consist of sugarberry, green ash, oaks, red maple, and red mulberry with a ground cover of greenbrier (Smilax spp.), American buckwheat vine or redvine (Brunnichia ovata), peppervine (Nekemias arborea), trumpet creeper (Campsis radicans), and eastern poison ivy (Toxicodendron radians). Species dominance patterns and presence will likely vary by location due to the natural variability of the local hydrology and soil-site environment and former landuse practices.

Broadfoot (1976) listed several species that are both favored in management and that frequently occur on the dominant soils of this site, the Dundee series, including Nuttall oak, cherrybark oak, water oak, willow oak, and sweetgum. Broadfoot also listed the following associates to favor in management that occasionally occur on these soils: green ash, eastern cottonwood, American sycamore, swamp chestnut oak, and pecan. As an example of the productivity of this site, the following are site index ranges (tree height in feet at 50 years except cottonwood which is 30 years) of the preceding species from Broadfoot (1976): Nuttall oak – 85 to 105; cherrybark oak – 90 to 110; water oak – 85 to 105; willow oak – 90 to 110; sweetgum – 90 to 110; green ash – 70 to 90; eastern cottonwood – 90 to 110; American sycamore – 95 to 115; swamp chestnut oak – 70 to 90; pecan – 80 to 100.

Of extreme importance and caution, the preceding site indices and management statements may vary or differ on wetter areas and poorly drained soils. Additionally, the sweet gum – water oaks (or red oaks) association may be transitory and without management could transition to a predominantly shade tolerant community, such as the sugarberry – American elm – green ash association, over time (Hodges, 1997).

The arrangement of tree species listed in the Dominant Plant Species table below follows the same order of importance (i.e., decreasing dominance) as indicated in the sweetgum – water oaks forest type in Putnam (1951). Putnam's list is interpreted to be more representative of natural variability than ranking the species by commercial value.

Dominant plant species

sweetgum (Liquidambar styraciflua), tree
water oak (Quercus nigra), tree
Nuttall oak (Quercus texana), tree
willow oak (Quercus phellos), tree
American elm (Ulmus americana), tree
sugarberry (Celtis laevigata), tree
green ash (Fraxinus pennsylvanica), tree
pecan (Carya illinoinensis), tree
water hickory (Carya aquatica), tree
possumhaw (Ilex decidua), shrub
roughleaf dogwood (Cornus drummondii), shrub
hawthorn (Crataegus), shrub
American hornbeam (Carpinus caroliniana), shrub
greenbrier (Smilax), shrub
eastern poison ivy (Toxicodendron radicans), shrub
peppervine (Nekemias arborea), shrub
American buckwheat vine (Brunnichia ovata), shrub
trumpet creeper (Campsis radicans), shrub
Carolina coralbead (Cocculus carolinus), shrub
Virginia creeper (Parthenocissus quinquefolia), shrub

State 2
Commercial Forestland

This state consists of two very different community phases and management approaches. Community Phase 2.1 represents forest management and production on this site. A distinguishing feature of this phase is the level of management intensity designed to maximize merchantable goals. Various silvicultural methods are available for selection, and these are generally grouped into even-aged (e.g., clearcutting, seed-tree, and shelterwood) and uneven-aged (e.g., single tree, diameter-limit, basal area, and group selection) approaches (Meadows and Stanturf, 1997). Depending on the method selected, different structural and compositional characteristics of the stand may result. Removal and control of community associates are typically a critical element of production goals. These actions may result in different community or “management phases” (and possibly alternate states) depending on the methods used and desired results. Finding the appropriate approach for a given stand and environment necessitates close consultation with trained, experienced, and knowledgeable forestry professionals. If there is a desire to proceed with this state, it is strongly urged and advised that professional guidance be obtained and a well-designed silvicultural plan developed in advance of any work conducted.

Community Phase 2.2 represents conditions of many stands that have incurred indiscriminate timber harvests (e.g., heavy cutting, diameter-limit or partial harvests of select species) and opportunistic regrowth following such harvests (i.e., no management at any period). Some stands may continue to support a few desirable species and quality stems, but in many instances, affected stands will be comprised of mostly shade tolerant species and/or trees of desirable species that fail to meet their maximum potential.

Although this site is well suited for forest production, seasonal wetness imposes moderate to severe limitations for some forest operations. Heavy equipment usage on wet soils can cause compaction, which may reduce site productivity. If possible, equipment operations are best conducted during drier periods of the year, which minimizes soil damage, erosion, and helps to maintain productivity.

An important caveat of this state is its representation of forest conditions that have retained full site production potential. Currently, transitional pathways to this state originate from another forested state (State 1), only. Former landuses (alternate states) that result in soil compaction (increased bulk densities), lower soil organic matter content, altered fertility, and smaller available rooting volume can reduce forest site production by 10 to 20 percent for some species (Groninger et al., 1999). These are conservative percentage reductions. The model from the Baker and Broadfoot (1979) method of site evaluation have produced site index values of over 20 percent lower than trees measured on non-impacted, forest soils. These impacts, however, can be ameliorated through various “afforestation” techniques such as plow pan breakup (subsoil or deep plowing), fertilization, and fallowing fields before stand establishment (Emile Gardiner, USFS Research Forester, personal communication with Rachel Stout Evans, contributing author). State 6 (Forest Recovery) is representative of forest establishment and growth on locations where soil compaction and reduction of nutrients have occurred. Once a previously affected location has recovered its site potential, transition to this state may be possible. That potential transition is still under review and is currently not shown or addressed in the state and transition model.

Community 2.1
Forest Management

Prescribing a silvicultural system for a given stand depends on species composition; long term production and postproduction goals; and the presence and abundance of advance regeneration (i.e., the presence of seedlings and saplings of the desired species). The canopy trees listed in State 1 as “favored in management” are all production options on this site ranging from single species plantations to complex multi-species stands. (Species favored in management are listed below for convenience.)

Establishing and maintaining oaks on bottomland sites may be preferred given the multiple values they provide (e.g., timber and wildlife). However, maintaining that component beyond a single rotation (or harvest) may be the most challenging. Creating conditions that promote oak persistence in future stands require a sufficient advance regeneration component. Ensuring that this future crop is established will require close adherence to a well-designed silvicultural plan, which requires programmatic intermediate operations (e.g., improvement cuttings, thinnings, and other partial cuttings). An even-aged silvicultural system that utilizes the clearcutting regeneration method along with brush management to reduce subsequent competition is typically the advocated approach when harvesting bottomland oak stands (Johnson and Shropshire, 1983; Clatterbuck and Meadows, 1993; Hodges, 1995; Meadows and Stanturf, 1997).

Except pecan, the remaining trees that are favored in management are light-seeded species. A variety of silvicultural systems may be implemented to promote production of these species including even-aged and group selection (uneven-aged) approaches (see Meadows and Stanturf, 1997).

Community 2.2
Non-managed/High-graded

This forest community is directly influenced by former harvesting practices that include repeated single-tree selection or diameter-limit harvests with no additional management activities (e.g., brush management, competitor control, etc.). These practices typically target the highest quality trees of the most desirable species. The result is usually an expansion and in-filling of shade tolerant subcanopy trees. Over time, this practice will lead to a predominantly shade tolerant community that may be comprised of a variant of the sugarberry – American elm – green ash forest association, possibly with a plurality of sugarberry and elm. Additional shade tolerant components likely to occur consist of red maple, boxelder, red mulberry, roughleaf dogwood, and possumhaw.

Pathway 2.1A
Community 2.1 to 2.2

Heavy cutting of the stand that removes the desired species (typically shade intolerant species) of sufficient diameters followed by no management of the residual stand. This pathway also includes repeated single-tree harvests (e.g., diameter-limit cuts) that removes the desired species followed by no management of the residual stand. The resulting stand is typically comprised of shade tolerant species with low commercial value.

Pathway 2.2A
Community 2.2 to 2.1

Intensive management will be required to push a shade tolerant community into a more commercially desirable and viable system. Actions will likely require a complete clearcut of the stand followed by repeated brush and competitor control (chemical and mechanical). If there is a lack of seed source, artificial regeneration will likely be required to reintroduce heavy-seeded species (oaks and pecan). Continual competitor control will be needed.

State 3
Cropland

This state is representative of the dominant landuse activity on this ecological site, agriculture production. The dominant crops grown on this site are rice (Oryza sativa) and soybeans (Glycine max) (USDA-NRCS, 2006b). Additional crops include corn (Zea mays), small grains such as wheat (Triticum aestivum), and cotton (Gossypium hirsutum) (Snipes et al., 2005). Minor crops, such as some specialty crops (e.g., fruits, vegetables, and tree nuts such as pecans), may be grown locally depending on local hydrology and the soil-site environment.

The soils of this site are well suited to agriculture production. Management concerns are centered on seasonal wetness, soil compaction from heavy equipment operations, and the development of a plow pan. These soils can be sticky when wet and hard when dry (USDA-NRCS, 2006b). Pringle et al. (2017) emphasized that a “fairly impermeable crust” tends to develop following a heavy rain or an irrigation event. Each of these factors could affect yields or impede optimum operation. Management measures to ameliorate some of these issues may include implementation of a drainage system or network; implementing a conservation tillage or management system; subsoiling to breakup plow pans (USDA-NRCS, 2006b). Major components that producers generally develop and plan are proper selection of crop cultivar, pest control, cropping system, tillage methods, nutrient management, and water management. Key practices of some cropping systems often include two or more crops grown in a multiyear rotation, which has been documented to disrupt pest cycles. Leaving crop residue on the surface can help to maintain tilth, fertility, and organic matter content – all critical elements of soil quality and health. For monoculture cropping systems, the implementation of well-designed pest and nutrient management systems are imperative (Pringle et al., 2017). (For assistance, interested parties are advised to visit their local NRCS Field Office.)

Three separate management phases comprise this state: Conservation Management (3.1), Transitional Conservation Management (3.2), and Conventional Management (3.3). The three phases consist of varying tillage methods and approaches to soil health management systems.

Community 3.1
Conservation Management

This cropland phase utilizes long term, continuous conservation management systems that include reduced till and cover crops; no-till with cover crops; crop residue retention; and perennial cropping systems. The guiding principles of this system are minimizing soil disturbance and maximizing soil cover, biodiversity, and the presence of living roots. Implementing diverse crop rotations while maintaining these principles can lend to the development of an integrated pest management plan and contribute to overall system resilience.

Of caution, the above-ground crop growth or yields may not be the best tracking mechanism for assessing the efficacy or presence of this management phase. Indicators of these systems are generally determined via soil-site assessments with outcomes that may include enhanced soil aggregate stability, increased soil biological activity, higher organic matter content, and improved water holding capacity and infiltration rates while also alleviating soil compaction and reducing runoff and erosion (Chessman et al., 2019). Additional advantages to this system that have been noted by some producers are reductions in fuel and labor costs and less wear and tear on machinery and equipment.

There are challenges to this management system, especially in situations where tillage may be considered and/or needed to repair weather damage or other detrimental impacts. Implementation of conventional tillage even after long term conservation practices (e.g., no-till) can reset the affected area back to a conventional cropping system. However, those changes can be reversed and a return to a conservation management system is achievable.

Critical conservation practices associated with this phase include cover crops, no-till, and reduced till as the foundational practices. Additionally, this phase may include supporting and/or site-specific practices to address conservation needs for a given location.

Community 3.2
Transitional Conservation Management

This cropland phase utilizes a hybrid approach that combines conventional methods with conservation practices at specific periods and under specific situations. Practices under this phase may include a combination of conventional till, reduced till, strip till, and the inclusion of cover crops. For instance, perennial crop species could be in a continuous transitional phase where conventional tillage is implemented at the time of planting followed by reduced tillage during the rotation. Planted forage crops could also be included in this phase, especially when part of a crop rotation that utilizes reduced tillage for one crop followed by conventional tillage for a succeeding crop.

The development, implementation, and refinement of nutrient and pest management plans throughout component operations are imperative. Additionally, this phase may include supporting and/or site-specific practices to address conservation needs for a given location.

Community 3.3
Conventional Management

This management phase is representative of conventional cropland where tillage is implemented as an annual component of the production system. As crucial elements of the system, conservation practices such as nutrient and pest management are needed to address fertility requirements and pest concerns within the crop cycle. It is important to note that this phase may develop when tillage is implemented to address damage or for other purposes while under a conservation management system (Community Phase 3.1). There could also be associated, supporting, and site-specific practices that are needed to address specific conservation needs. Specific needs may include grade stabilization structures to control gully erosion, grassed waterways to trap sediment from sheet and rill erosion, or implementing reduced till.

Pathway 3.1A
Community 3.1 to 3.2

Soil disturbance (tillage); reduction of soil health.

Pathway 3.1B
Community 3.1 to 3.3

Conventional tillage, seeding, and fertility management for crops.

Pathway 3.2A
Community 3.2 to 3.1

No-till, cover crops, reduced till–soil health improvements.

Pathway 3.2B
Community 3.2 to 3.3

Conventional tillage, seeding, and fertility management for crops.

Pathway 3.3A
Community 3.3 to 3.2

Reduced till, no-till, and cover crops with soil health improvements as a goal.

State 4
Land Formed Cropland

This nearly level ecological site typically adjoins gently sloping, and sometimes undulating, landscapes. It is bordered by soils of varying textures and drainage characteristics. Accordingly, inconsistencies in wetness, ease of operation, and production or yields may occur across a cropped location. An increasingly common practice on this site consists of land forming or leveling surface irregularities into a predetermined and engineered, uniform slope. This practice removes the drier and higher features of this site, which are then used to fill wetter and lower positions (e.g., depressions or swales) across the targeted area. Advantages of land leveling may include reduced hazards of erosion and runoff rates, improved surface drainage, and enhanced distribution and conservation of irrigation water. Disadvantages of the practice is a churning of various surface and subsurface materials (former soil horizons) that no longer occur in a predictable or regular pattern. Organic matter content in the surface layer is generally low, and the surface tends to crust and pack after heavy rains (USDA-NRCS, 2006b). One potential hazard that appears to be emerging in some areas is an effective management of surface water runoff. As both irrigated and stormwater runs off leveled fields at uniform rates, surface water tends to collect cumulatively and simultaneously, which places tremendous demands on local drainage networks. Without “in field” structures (natural or artificial) to stagger runoff, the downslope (or lower) ends of some fields tend to back flood thereby contributing to more flooding overall in local watersheds (personal observations).

Immediately following land leveling, the constituent elements of soil health are likely to be absent. In some areas, producers have initiated practices such as applying organic residues (e.g., poultry litter) or growing rice crops for one to two years to rapidly boost fertility and introduce organic matter (via rice biomass) in the surface layer. Over time, the full complement of the management (or community) phases of State 3 may be possible on land leveled fields. They are not repeated or indicated here.

Currently, this state serves as an endpoint in the state and transition model because the ability to predict vegetation response when transitioning to a different state is no longer possible without soil-site investigations for each area of interest. The former soils of this ecological site, including surface and subsurface horizons, will have been redistributed as particles among other former soils.

Community 4.1
Land Leveled Cropland

Some of the crop species and management practices indicated and discussed in State 3 (including all three management phases) may be suitable for establishing on land leveled areas that once supported the soils of this site. However, the type of crops suited for newly leveled areas may ultimately depend on the prevailing soil particle-size distribution and internal drainage characteristics. Former studies on precision leveled fields have noted variabilities and inconsistencies in soil particle-size distributions, bulk density, soil biological properties, and nutrients (Brye et al., 2003; Walker et al., 2003; Brye et al., 2006). Management concerns for this phase may consist of restricted permeability, low organic matter content, and crusting and packing (USDA-NRCS, 2006b). These impacts may be improved by implementing conservation tillage, cover crops, retaining crop residue, and nutrient and pest management strategies.

State 5
Pastureland/Grassland

This state is representative of sites that have been converted to and maintained in pasture or grassland. The soils of this site are generally considered well suited to most commonly grown perennial forage species. However, there are wetness limitations due to a seasonally high water table, which could restrict root growth. Maintaining an adequate crop of cool season annual forage may be challenging and is generally considered not suited. Management concerns are mainly centered on soil compaction due to grazing, which may be improved or avoided by restricting grazing during wetter periods (USDA-NRCS, 2006b). Of caution, some annual winter plants naturally growing in wet locations (e.g., sedges and rushes) may be hazardous if consumed. Production is considered moderate when adequately fertilized and properly managed.

Given that this ecological site occurs on lower, wetter sites, some forage operations may experience multiple wetness events in a single year. Flood-prone areas may limit the type of forage suited for this site. In areas that flood on a regular basis, implementing management actions such as planting or overseeding appropriate cool season forage varieties (e.g., cultivar ‘Marshall’ ryegrass, Lolium perenne ssp. multiflorum; also known as annual ryegrass) into established warm season grasses at heavy forage rates have been observed to help protect riparian areas from detrimental river or stream scouring (personal observations by Rachel Stout Evans, contributing author). Initiating such remedial actions aid in the recovery and reestablishment of preferred warm season forage such as bahiagrass (Paspalum notatum) following seasonal flooding. (Note that herbicide resistant varieties could be problematic and may warrant reconsideration. Please consult with local NRCS Field Offices for assistance.) Where permissible, a system of artificial drainage or water control structures may be in place to facilitate continued forage production and grazing during wetter periods. Additionally, adjacent higher elevation or protected areas may be needed for the storage of harvested forage or holding of livestock when wet or flooded conditions occur.

Establishing an effective pasture management program can help minimize degradation of the site and assist in maintaining growth of desired forage. An effective pasture management program includes selecting well-adapted grass and/or legume species that will grow and establish rapidly; maintaining proper soil pH and fertility levels; using controlled grazing practices; mowing at proper timing and stage of maturity; allowing new seedings to become well established before use; and renovating pastures when needed (Rhodes et al., 2005; Green et al., 2006).

This state consists of four community phases that represent a range of forage management options and pasture/hayland condition scenarios. Options range from establishing a forage monoculture for haying to a broad mixture of forage species for production and grazing. It is strongly advised that consultation with local NRCS Service Centers be sought when assistance is needed in developing management recommendations or prescribed grazing practices.

Community 5.1
Monoculture Grassland

This phase is mainly characterized by planting forage species for hay production. Forage plantings generally consist of a single grass species. Native and 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 and nutrient management.

Generally, the application of fertilizer and lime is needed to establish and maintain improved desirable pastures. Exceptions do occur for bahiagrass (Paspalum notatum) and common Bermudagrass (Cynodon dactylon), which can be sustained under natural fertility and pH levels. Introduced grasses, such as hybrid Bermudagrass, require a higher level of sustained fertility, pH above 6.0, and good surface drainage to persist. An additional measure to aid production may include prescribed grazing. Implementing limited and monitored grazing can promote deeper root penetration of grasses with the added benefit of greater nutrient and moisture uptake. This synergistic approach can lead to increased production of and may sustain desirable forages.

Conservation practices should include prescribed grazing, or forage harvest management, nutrient and pest management, and potentially other site-specific practices.

Dominant plant species

tall fescue (Schedonorus arundinaceus), grass
Bermudagrass (Cynodon dactylon), grass
dallisgrass (Paspalum dilatatum), grass
bahiagrass (Paspalum notatum), grass

Community 5.2
Mixed Species System

This community is characterized by mixed species composition of grasses and legumes. Components of this forage system are either planted or they established naturally. Typically, perennial warm-season grasses are the foundation of the stand that are periodically overseeded with adapted cool-season forages. The latter creates an added benefit of extending 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 series of management practices such as prescribed grazing, brush management, pest management, and nutrient management to maintain production of the desired species. Prescribed grazing includes maintaining proper grazing or forage heights, timing, and stocking rates. Supporting or facilitating practices such as fences, water lines, and watering facilities could be part of the system that maintains this phase.

Dominant plant species

tall fescue (Schedonorus arundinaceus), grass
Bermudagrass (Cynodon dactylon), grass
dallisgrass (Paspalum dilatatum), grass
bahiagrass (Paspalum notatum), grass
white clover (Trifolium repens), other herbaceous

Community 5.3
Mixed Species, Non-seeded

This community is characterized by a mixture of native and naturalized non-native species. Forage is usually grazed and/or harvested as stored forage, hay or haylage. Common established species may include tall fescue, Bermudagrass, bahiagrass, Vasey grass (Paspalum urvillei), and carpetgrass (Axonopus sp.).

Stands are generally productive, and forage and grazing management can maintain the community. Healthy stands provide additional benefits by protecting soils from excessive runoff and erosion. However, a common peril associated with this phase is overgrazing, which lowers production and favors less palatable weedy species, especially in areas where livestock congregate. Proper stocking rates 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 develop deeper root systems and greater leaf area. Conversely, when plants are not allowed to adequately recover, root development will be restricted leading to lower forage and biomass production. Additionally, maintenance of grass stands requires implementing pest management practices to control unwanted weedy and woody species.

Community 5.4
Early Woody Succession

This community is characterized by a diverse composition of grasses and forbs with an increasing presence of woody species (both native and non-native) that are immature and of low stature. Woody species grow quickly on this site and can be difficult and expensive to control. One potentially problematic species may be honeylocust (Gleditsia triacanthos). Putnam (1951) reported honeylocust as being common on old pastures, and the species can be difficult to remove once established. Management to transition this phase to other forage communities of this state is still possible without excessive inputs and effort, particularly if stem diameters remain below 2 inches and are widely scattered (e.g., a density of less than 100 stems per acre). However, if diameters become greater than 3 inches and densities exceed 300 stems per acre, far more investment, effort, and inputs will be required. If brush management measures are not undertaken, the plant community will transition to the Ruderal/Opportunistic Regrowth (Community Phase 6.1) of State 6.

Of note, this community phase is often very beneficial habitat for some wildlife species, especially a specific guild of resident and Neotropical migratory bird species that depend on old field to young tree stand habitats.

Pathway 5.1A
Community 5.1 to 5.2

Seeding and/or management for desired species composition.

Pathway 5.1B
Community 5.1 to 5.3

Species management without overseeding.

Pathway 5.2A
Community 5.2 to 5.1

Seeding, fertilizing, management/removal of undesirable species.

Pathway 5.2B
Community 5.2 to 5.3

Species management without overseeding

Pathway 5.3A
Community 5.3 to 5.1

Seeding, fertilizing, management/removal of undesirable species.

Pathway 5.3B
Community 5.3 to 5.2

Seeding and/or management for desired species composition.

Pathway 5.3C
Community 5.3 to 5.4

Lack of disturbance; no (infrequent) mowing, herbivory, or brush management; natural succession of woody species.

Pathway 5.4A
Community 5.4 to 5.3

Brush management/removal of unwanted species.

State 6
Forest Recovery

This state is representative of forest recovery in areas that were once under former intensive landuse such as long-term row crop cultivation. Characteristics that distinguish this state from other forest states on this site include a suite of soil-site properties that reportedly affect tree growth such as higher soil bulk density due to compaction, presence of a plow pan, lower organic matter content, and reduced fertility (Baker and Broadfoot, 1979; Groninger et al., 1999). Two community phases are provisionally recognized for this state. Community Phase 6.1 represents natural colonization of vegetation without management. Community Phase 6.2 is representative of intentional forest establishment by planting.

For Community Phase 6.2, determining the objectives and goals of the future stand is imperative to increase the probability of successful establishment and production of the afforested area. These decisions will ultimately determine the species to be established, preparation requirements, planting density, and post-planting operations (e.g., competitor control, future improvement cuttings and thinnings, regeneration methods, and overall stand health). Since each area targeted for afforestation may have unique or different landuse histories, having a clear understanding of the soil-site conditions are essential. Some areas may necessitate a series of soil improvement actions prior to planting. These actions may include subsoiling or deep plowing to breakup plow pans and fertilizing the targeted area. An additional option is to allow the area to undergo fallowing for a predetermined period (Community Phase 6.1) to potentially increase soil organic matter content, enhance soil aggregate stability, increase soil biological activity, and improve water holding capacity and infiltration rates. Controlling competing vegetation (chemical and mechanical treatment) will be critical, although ensuring seedling survival and enhanced tree growth on fallow fields after weed control treatments have not always been met with positive results (Groninger, 2005). Still, post-planting operations and maintenance of the stand are necessary steps to increase the probability for enhancing survival, future development, and achieving goals and objectives (see Gardiner et al., 2002).

Finding the appropriate approach for a given environment necessitates close consultation with trained, experienced, and knowledgeable forestry professionals. If there is a desire to proceed with this state, it is strongly urged and advised that professional guidance be obtained and a well-designed afforestation and silvicultural plan developed in advance of any work conducted. For an exceptional review and summary of the afforestation literature, techniques, and practices within the Southern Mississippi River Alluvium, interested parties are directed to Gardiner et al. (2002).

Community 6.1
Ruderal/Opportunistic Regrowth

This community phase is representative of former working lands (e.g., cropland and possibly high concentration areas of former pastureland) that have fallowed and subsequently undergone natural colonization by vegetation. A profusion of growth will likely initiate within five to ten years of becoming idle – one that typically includes grasses, forbs, woody seedlings and shrubs, and an increasing presence and covering of vines. Initial colonization may be dominant in annuals followed by a shift to perennial vegetation. Shrubs and tree seedlings may appear very early following abandonment, however the rate of colonization and period to stand establishment likely depends on the proximity of established mature stands (Battaglia et al., 1995; Battaglia et al., 2002). If established stands consisting of light-seeded species adjoin fallow fields, colonizing tree species will likely be comprised of those taxa (e.g., green ash, elm, maple, sycamore, and cottonwood) (Allen, 1990; Stanturf et al., 2001). Some areas may be far removed from established forest stands. Under this scenario, establishment of woody species (especially overstory tree species) may be very slow, and years may be required before stand establishment is reached (Battaglia et al., 1995; Allen, 1997). In fact, natural colonization by some species may be delayed indefinitely with some stands or areas being understocked (Allen, 1997; Battaglia et al., 2002; Groninger, 2005). Heavy-seeded species like oaks and hickory may not have an opportunity to colonize available areas due to distance and lack of a dependable dispersing agent (e.g., wildlife and water). For those areas close to a viable seed source, oaks may be a component of the developing stand, although in the early stages of stand development oaks are likely to be a minor component (Meadows, 1993). Non-native invasive species may become part of the developing stand given the proliferation of exotic plant species over the past century.

It is extremely difficult, if not impossible, to predict the future composition and structure of an abandoned field on this site. Many different environmental factors will influence initial colonization and development trajectories. The following projections are simply based on native plant species reported to occur on the soils of this site. As the young stand matures and eventually enters the stem exclusion stage (crown or canopy closure), composition may include American elm, green ash, cedar elm, boxelder, American sycamore, red maple, sugarberry, and sweetgum. Oaks that may occur in the young stand include willow, water, and Nuttall with overcup potentially occurring in wetter locations. Problematic non-native species that may occur include Japanese honeysuckle (Lonicera japonica), Chinese privet (Ligustrum sinense), and possibly Callery pear (Pyrus calleryana). Vines common in the young, developing stand may include greenbrier, eastern poison ivy, peppervine, American buckwheat vine, and trumpet creeper. As the stand matures decades into the future and the overstory stratifies (i.e., the understory reinitiation stage), shade tolerant species may dominate the stand and the community could transition to an elm – ash – sugarberry association or a variant of this type.

Community 6.2
Afforestation

This community phase is representative of areas planted in tree species that are suited for and favored in management on this ecological site. Preparation of this phase may be initiated immediately following a former landuse activity (e.g., State 3) or it may be started following a fallow period (Community Phase 6.1). If afforestation is initiated immediately following years of conventional tillage without soil-site preparation and improvement efforts, potential productivity of the targeted area could be less than optimal if soil compaction, plow pan presence, degraded fertility, and/or depleted organic matter content are existing factors (Baker and Broadfoot, 1979; Groninger et al., 1999; Gardiner et al., 2002).

Groninger et al. (1999) utilized the Baker and Broadfoot (1979) model for site evaluation to predict potential productivity of green ash, Nuttall oak, American sycamore, sweetgum, swamp chestnut oak, water oak, and cottonwood on what they termed “marginal soybean lands.” These are croplands occurring on frequently flooded areas that typically produce low average soybean yields where conventional tillage is utilized. Soils associated with these areas are generally poorly drained, clayey, and typically classified as hydric. The dominant soil series of this site, Dundee soils, were included for evaluation. Based on information presented in Groninger et al. (1999), site index predictions on conventional tillage cropland ranged from 9 to 16 percent lower than what are generally reported in soil survey manuscripts and in Broadfoot (1976). (Note, prediction values differed with respect to species.) The site index predictions in Groninger et al. assumes that no soil-site improvement actions were undertaken.

Over the years, various afforestation innovations have increased the likelihood of success in addition to soil-site amelioration such as planting large, high-quality seedlings with well-developed root systems in an appropriate cover crop (Dey et al., 2010); interplanting seedlings within a fast-growing pioneer species nurse crop (e.g., cottonwood) (Gardiner et al., 2001); and planting companionable species combinations for mixed species stands (Lockhart et al., 2008). The cover crop and nurse crop approaches reportedly help to control rapid overtopping and crowding by competing vegetation and wildlife herbivory (Dey et al., 2010). Finding the appropriate strategy for a given location requires matching the species to the local hydrologic and soil-site environment; determining short- and long-term objectives and goals; and implementing the appropriate management actions at the required intervals.

Several species that frequently occur and favored in management (see State 1) are likely appropriate for planting on this ecological site. However, Broadfoot (1976) listed a much narrower group of hardwoods suitable for planting on the dominant soils of this site, and they are green ash, Nuttall oak, sweetgum, Shumard’s oak, American sycamore, and eastern cottonwood.

Pathway 6.1A
Community 6.1 to 6.2

Remove undesirable competitors; final soil preparation; establish site-appropriate species (favored in management).

State 7
Conservation (Herbaceous)

This state is representative of the range of conservation actions that may be implemented and established on this ecological site. Apart from planting trees and managing for forest, one may elect to establish native herbaceous species and manage for predominantly a native grassland; a complex mixture of native grasses and forbs; or a pollinator planting whereby native forbs dominate the mix. In each of these options, it is strongly advised (possibly a programmatic requirement) that the species comprising the planting or seed mix consist of spring, summer, and fall flowering species. Depending on goals and objectives, various conservation programs and practices may be available. For additional information and assistance, please contact or visit the local NRCS Field Office.

Community 7.1
Pollinator Planting/Native Grasses

This community phase represents the establishment of native forbs or wildflowers for pollinator habitat and/or native grasses. The seed mix for planting may be quite varied depending on objectives and goals. Ideally, the mix includes a wide range of species that flower at various times of the growing season (spring, summer, and fall). Plant species in some pollinator mixes may include but are not limited to beebalm (Monarda spp.), milkweeds (Asclepias spp.), beardtongue (Penstemon spp.), cardinalflower (Lobelia cardinalis), vervain (Verbena spp.), various legumes such as native lespedeza (Lespedeza spp.), Illinois bundleflower (Desmanthus illinoensis), partridge pea (Chamaecrista fasciculata), and a broad assortment of composites such as asters (Symphyotrichum spp.), tickseed (Coreopsis spp.), blazing star (Liatris spp.), coneflower (Rudbeckia spp.), sunflower (Helianthus spp.) among many others. If goals and objectives are to establish native grasses within a forb mix or in a grass-dominant stand, species suitable for planting may include switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium) Indiangrass (Sorghastrum nutans), and eastern gamagrass (Tripsacum dactyloides).

Key to the establishment of this phase is initial preparation, seeding rate, planting period, follow-up treatment, and maintenance of the planting. The selection of species to establish on any given area may ultimately depend on size and conditions of the location where the planting will occur, landowner/manager goals and objectives, and the advice and knowledge of the conservation practitioner.

Transition T1A
State 1 to 2

Stand composition is heavily altered and managed to favor select species for production (Community 2.1). This transitional pathway also includes heavy timber cutting and/or high-grading leading to Community 2.2.

Transition T1B
State 1 to 3

Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for cultivation.

Transition T1C
State 1 to 5

Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; seedbed preparation; and establishment of desired forage.

Transition T2A
State 2 to 1

This transition represents a return to perceived reference conditions and involves the re-establishment of missing species; the control/removal of exotic species (herbicide and mechanical); stand improvement practices that favors a return of more shade intolerant components.

Transition T2B
State 2 to 3

Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; and preparation for cultivation.

Transition T2C
State 2 to 5

Actions include mechanical removal of vegetation and stumps; herbicide treatment of residual plants; seedbed preparation; and establishment of desired forage.

Transition T3A
State 3 to 4

Precision land leveling

Transition T3B
State 3 to 5

Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing

Transition T3C
State 3 to 6

Natural succession (Community 6.1) or site prep (plow pan breakup, fertilizing, etc.); planting species appropriate for site (Community 6.2)

Transition T3D
State 3 to 7

Establish select native species suitable for site; prep site for planting (herbicide and/or mechanical)

Transition T5A
State 5 to 3

Actions include mechanical removal of vegetation; herbicide treatment of residual plants; and preparation for cultivation.

Transition T5B
State 5 to 6

Natural succession (Community 6.1) or site prep (plow pan breakup, fertilizing, etc.); planting species appropriate for site (Community 6.2)

Transition T5C
State 5 to 7

Establish select native species suitable for site; prep site for planting (herbicide and/or mechanical)

Transition T6A
State 6 to 3

Cropland establishment: vegetation removal (mechanical/chemical) and preparation for cultivation

Transition T6B
State 6 to 5

Mechanical removal of vegetation and stumps; herbicide treatment of residual plants; establish desired forage species and manage for grazing

Transition T7A
State 7 to 3

Cropland establishment: vegetation removal (mechanical/chemical) and preparation for cultivation.

Transition T7B
State 7 to 5

Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing

Transition T7C
State 7 to 6

Natural succession (Community 6.1) or site prep (plow pan breakup, fertilizing, etc.); planting species appropriate for site (Afforestation - Community 6.2)

Additional community tables

Table 6. Community 1.1 plant community composition

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

Table 7. Community 2.1 plant community composition

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

Table 8. Community 2.2 plant community composition

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

Table 9. Community 3.1 plant community composition

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

Table 10. Community 3.2 plant community composition

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

Table 11. Community 3.3 plant community composition

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

Table 12. Community 4.1 plant community composition

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

Table 13. Community 5.1 plant community composition

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

Table 14. Community 5.2 plant community composition

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

Table 15. Community 5.3 plant community composition

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

Table 16. Community 5.4 plant community composition

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

Table 17. Community 6.1 plant community composition

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

Table 18. Community 6.2 plant community composition

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

Table 19. Community 7.1 plant community composition

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

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.

Other references

Allen, J.A. 1990. Establishment of bottomland oak plantations on the Yazoo National Wildlife Refuge Complex. Southern Journal of Applied Forestry 14(4): 206-210.

Allen, J.A. 1997. Reforestation of bottomland hardwoods and the issue of woody species diversity. Restoration Ecology 5(2): 125-134.

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.

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.

Baker, J.B. and W.M. Broadfoot. 1979. A practical field method of site evaluation for commercially important southern hardwoods. General Technical Report SO-26. Southern Forest Experiment Station, New Orleans, LA. 51p.

Battaglia, L.L., J.R. Keough, and D.W. Pritchett. 1995. Early secondary succession in a southeastern U.S. alluvial floodplain. Journal of Vegetation Science 6(6): 769-776.

Battaglia, L.L., P.R. Minchin, and D.W. Pritchett. 2002. Sixteen years of old-field succession and reestablishment of a bottomland hardwood forest in the Lower Mississippi Alluvial Valley. Wetlands 22(1): 1-17.

Blum, M.D., M.J. Guccione, D.A. Wysocki, P.C. Robnett, and M. Rutledge. 2000. Late Pleistocene evolution of the Lower Mississippi Valley, southern Missouri to Arkansas. Geological Society of America Bulletin 112: 221-235.

Broadfoot, W.M. 1976. Hardwood suitability for and properties of important Midsouth soils. USDA Forest Service Research Paper SO-127. Southern Forest Experiment Station, New Orleans, LA. 84 p.

Brye, K.R., N.A. Slaton, M.C. Savin, R.J. Norman, and D.M. Miller. 2003. Short-term effects of land leveling on soil physical properties and microbial biomass. Soil Science Society of America Journal 67: 1405-1417.

Brye, K.R., N.A. Slaton, and R.J. Norman. 2006. Soil physical and biological properties as affected by land leveling in a clayey Aquert. Soil Science Society of America Journal 70: 631-642.

Castilla, R.A. and F.A. Audemard. 2007. Sand blows as a potential tool for magnitude estimation of pre-instrumental earthquakes. Journal of Seismology 11(4): 473-487.

Chapman, S.S., J.M. Omernik, G.E. Griffith, W.A. Schroeder, T.A. Nigh, and T.F. Wilton. 2002. Ecoregions of Iowa and Missouri (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,800,000).

Chessman, D., B.N. Moebius-Clune, B.R. Smith, and B. Fisher. 2019. The basics of addressing resource concerns with conservation practices within integrated soil health management systems on cropland. Soil Health Technical Note No. 450-04. U.S. Department of Agriculture, Natural Resources Conservation Service. Available: https://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=44340.wba (Accessed: 9 September 2020).

Clatterbuck, W.K. and J.S. Meadows. 1993. Regenerating oaks in the bottomlands. p: 184-195. In: D.L. Loftis and C.E. McGee (Editors). Oak Regeneration: Serious Problems, Practical Recommendations. Symposium Proceedings, 8-10 September 1992, Knoxville, TN. General Technical Report SE-84. USDA Forest Service, Southeastern Forest Experiment Station, Asheville, NC.

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Contributors

Barry Hart
Rachel Stout Evans
Doug Wallace
Fred Young

Approval

Charles Stemmans, 6/10/2025

Acknowledgments

We are sincerely grateful to the MLRA 131A Technical Team for their assistance and input in the development of this report. Special recognition is owed to Tom Foti (Ecologist, Arkansas Natural Heritage Commission, Retired) and Henry Langston (Wetland Ecologist, Arkansas Department of Transportation, Retired) for their time, personal travel expenses, and willingness to share their vast knowledge of the region. Their assistance with field reconnaissance, identifying sites and locations for investigating, and verifying ecological factors across multiple Mississippi River basins has led to a deeper understanding of the ecological sites and their associated states and community phases in the Southern Mississippi River Alluvium.

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	08/21/2026
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 F131AY206AR

St. Francis - Wet Braided Interfluve Forest

Last updated: 6/10/2025 Accessed: 08/21/2026

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General information

MLRA notes

LRU notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Figure 1. Distribution of F131AY206AR.

Table 2. Dominant plant species

Natural Resources
Conservation Service

Last updated: 6/10/2025
Accessed: 08/21/2026