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Ecological site F131AY208AR

St. Francis - Sandy Natural Levee and Meander Scroll Forest

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

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General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

MLRA notes

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

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

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

The fluvial processes that shaped the area were highly dynamic, diverse, and complex. During the Pleistocene epoch, multiple continental glacial-interglacial cycles resulted in extreme fluctuations in river discharge and sediment loads. A braided river regime characterized the fluvial dynamics of the Mississippi River through much of the last glacial cycle (Autin et al., 1991; Rittenhour et al., 2007). Rapid aggradation of glacial outwash led to the development of prominent valley train features over a large portion of the area (Autin et al., 1991; Saucier, 1994; Aslan and Autin, 1999; Blum et al., 2000; Rittenour et al., 2007). A changing climate, meltwater withdrawal, and sea-level change induced a transition from a braided river regime to a predominantly single-channeled, laterally migrating river system during the Holocene epoch (Rittenhour et al., 2007; Shen et al., 2012) – characteristics that continue today. Fluvial dynamics of the migrating river resulted in the development of broad meander belts, backswamp environments, and extensive deltaic complexes (Saucier, 1994; Klimas et al., 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 broadly 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, 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; 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 Holocene Meander Belt, 73a; St. Francis Lowlands, 73c (Griffith et al., 1998; Chapman et al., 2002; Woods et al., 2002; Woods et al., 2004; Wiken et al., 2011)
- Mississippi River High Floodplain (Bottomland), CES203.196 (NatureServe, 2020)
- 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): F2, Well-drained recent alluvium in lowlands, Cherrybark Oak – Water Oak – Sweetgum

Ecological site concept

This site consists entirely of sandy soils that were primarily deposited during flood events and secondarily as inclusions of sand blows that were extruded or erupted to the ground surface during the New Madrid earthquakes of 1811-1812. Where the site developed following flood events, these deep, coarse-textured soils were initially deposited as sand splays along levee breaches and on point bars (convex bends) of the Mississippi River. It is critical to note that this site occurs on the “protected” side of the extensive Mississippi River levee system and is distinguished from similar soils and landforms within the “batture” (i.e., the alluvial land between the river channel and the constructed levee system). Therefore, the geomorphic positions of this site, today, mainly include the high spots of natural levees and meander scroll ridge crests of abandoned river segments (cut-offs) that were naturally separated from the main channel prior to levee construction. Additionally, the soils of this site have been mapped locally along a few tributaries to and along overflow channels of the Mississippi River. The inclusions of sand blows are often most evident where eruptions occurred in clayey backswamp environments. Natural vegetation of this site may vary depending on age of the site and successional stage. Components generally associated with the site include eastern cottonwood (Populus deltoides), American sycamore (Platanus occidentalis), river birch (Betula nigra), boxelder (Acer negundo), American elm (Ulmus americana), and may consist of pecan (Carya illinoinensis) where depth to moisture is shallow.

Associated sites

F131AY201AR	St. Francis - Wet Clayey Backswamp Flat The sandy soils of F131AY208AR occur in complex with the heavy clayey soils of F131AY201AR where sand blows extruded from layers beneath the overlying clay during the New Madrid earthquakes of 1811-1812.
F131AY209AR	St. Francis - Old Loamy Natural Levee and Meander Scroll Forest The soils of this site occur on the higher positions of former Mississippi River natural levees and meander scroll ridges, often alongside or at a slightly lower elevation to the sandy soils of F131AY208AR.
F131AY210AR	St. Francis - Old Moderately Wet Natural Levee and Meander Scroll Forest The soils of this site generally occur on a lower, mid-slope position of the former Mississippi River natural levees and meander scroll ridges, but in some locations, they adjoin the sandy soils of F131AY208AR at a slightly lower elevation.
F131AY212AR	St. Francis - Recent Loamy Natural Levee and Meander Scroll Forest This ecological site occupies high positions on natural levees and meander scroll ridges of the most recent Mississippi River meander belt. During major flood events, large crevasse splays (F131AY208AR) are deposited on and adjacent to the loamy natural levees and ridges of site F131AY212AR.
F131AY213AR	St. Francis - Recent Moderately Wet Natural Levee and Meander Scroll Forest This ecological site occupies positions intermediate to the higher, better drained areas and the lower, wetter toeslopes of recent natural levees and meander scroll ridges. During major flood events, large crevasse splays or heavy sand deposits (F131AY208AR) can occur on and adjacent to the somewhat poorly drained natural levee and meander scroll positions of site F131AY213AR.

Similar sites

F131AY305MS	Yazoo - Old Sandy Natural Levee and Meander Scroll Ridge Forest This site supports similar soils and occur on similar geomorphic features and positions as F131AY208AR. The principal difference is F131AY305MS occurs within the Yazoo Basin.
F131AY407LA	Tensas Basin - Pointbars, Sandbars, and Splays This site supports similar soils and occur on similar geomorphic features and positions as F131AY208AR. The principal difference is F131AY407LA occurs within the Tensas Basin.
F131AY606MS	Batture - Frequently Flooded Pointbars, Sandbars, and Splays This site supports similar soils that occur on similar geomorphic features and positions as F131AY208AR, but they differ dramatically in their ages and time periods of deposition. The soils of F131AY606MS are of very recent origin and are undergoing active deposition, whereas the soils of F131AY208AR are generally older and more weathered. Some locations have been abandoned by the parent stream for centuries. Conversely, site F131AY606MS occurs within the active floodway and associated floodplain of the current Mississippi River channel.
F131AY309MS	Yazoo - Recent Sandy Natural Levee and Meander Scroll Ridge Forest This site supports similar soils and occur on similar geomorphic features and positions as F131AY208AR. The principal difference is F131AY309MS occurs within the Yazoo Basin.

Figure 1. F131AY208AR distribution.

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	Not specified

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Physiographic features

This ecological site is broadly mapped on multiple geomorphic features in the St. Francis Basin. The sandy soils of this site are perhaps most representative of the Mississippi River meander belt environment, both the more recent meander belt but also much older features that were abandoned by the parent stream long ago. These very deep, moderately well to excessively drained soils were initially deposited as sand splays along levee breaches, in narrow bands paralleling overflow channels, and as river deposits on point bars (convex river bends). Where fluvial processes result in the undulating “ridge and swale” topography (e.g., meander scrolls), the soils of this site occupy the higher positions. This site also occurs along major tributaries to the Mississippi River where former flood events resulted in heavy sand deposition.

A secondary but notable attribute of this site is the incidence of a subset of these soils that were deposited on the surface by seismic rather than fluvial processes. There are large delineations of sandy soils occurring in complex with thick beds of clayey soils. These delineations most frequently occur on Holocene flood basins (or backswamp environments) and on adjoining low, Late Pleistocene valley trains that were heavily veneered by repeated Holocene flood events (interpreted from Saucier, 1994). The presence of sandy soils that formed in this environment occur in patches or low mounds that dot the surfaces of the surrounding clayey soils (USDA-SCS, 1971). These mounds are extrusions or eruptions of sand that were blown from fissures during the New Madrid earthquakes of 1811-1812. The “normal” or most common occurrence of the “sand blows” (or sand boils) are somewhat circular ranging from 8 to 15 feet across and 3 to 6 inches high (Fuller, 1912). Locally, some blows are more elongated and impressive, extending to 100 feet wide and 600 feet or more long (USDA-SCS, 1971). According to Castilla and Audemard (2007), these are “…the largest ever-reported isolated sand blows.” Presumably, the origins of the sandy soils were buried deposits of glacial outwash (Klimas et al., 2013).

Figure 2. Recent Mississippi River natural levee catena. Bruno soils are a component of F131AY208AR.

Table 2. Representative physiographic features

Landforms	(1) Meander belt > Natural levee > Rise (2) Meander belt > Meander scroll > Rise (3) Alluvial plain > Backswamp > Sand boil (4) Alluvial plain > Flood-plain splay > Rise
Runoff class	Negligible to medium
Flooding duration	Long (7 to 30 days)
Flooding frequency	None to frequent
Ponding frequency	None
Elevation	150 – 315 ft
Slope	8%
Water table depth	24 – 60 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 3. Representative climatic features

Frost-free period (characteristic range)	177-186 days
Freeze-free period (characteristic range)	214-220 days
Precipitation total (characteristic range)	47-50 in
Frost-free period (actual range)	167-193 days
Freeze-free period (actual range)	200-223 days
Precipitation total (actual range)	46-52 in
Frost-free period (average)	181 days
Freeze-free period (average)	215 days
Precipitation total (average)	49 in

Characteristic range

Actual range

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Figure 3. Monthly precipitation range

Characteristic range

Actual range

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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) BLYTHEVILLE MUNI AP [USW00053869], Blytheville, AR
(10) PARAGOULD 1S [USC00035563], Paragould, AR
(11) KEISER [USC00033821], Keiser, AR
(12) WEST MEMPHIS MUNI AP [USW00053959], Marion, AR

Influencing water features

This site occupies the highest positions of old and more recent natural levees and meander scroll ridges, banks of active and abandoned tributaries and overflow channels, and as sand blows on poorly drained flood basins. The location or position of this site on Mississippi River meander belts is high enough in elevation that it does not flood on a frequent or predictable basis. Exceptions to this are locations where the soils occur beside or near active tributaries and in flood basins. Those locations may receive overland flooding (and back flooding in some areas) during severe flood events. In general, this site does not support obligate wetland species or exhibit hydric characteristics and is not a wetland.

Soil features

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

This site is characterized by very deep sandy soils. Drainage classification of the assembled list of soils ranges from moderately well to excessively drained. Soil reactions range from strongly acid to moderately alkaline. Slopes associated with the higher positions of this site generally range from 0 to 8 percent and sometimes occur in an undulating pattern, particularly on ridge and swale topography of meander scrolls. Soils provisionally correlated to this site consist of the Beulah, Bruno, Crevasse, and Steele series.

The Beulah (coarse-loamy, mixed, active, thermic Typic Dystrudepts) series consists of somewhat excessively drained soils that formed in loamy and sandy alluvium. These soils have moderately rapid permeability and runoff that ranges from slow to moderate. Of the soils associated with this site, they have the most pedogenic development as signified by the presence of a cambic horizon 8 to 28 inches (Bw1 and Bw2) below the surface. Reaction ranges from strongly acid to neutral in the A horizon, strongly to slightly acid in the Bw horizon, and strongly acid to neutral in the C horizon. Slopes range from 0 to 8 percent and are sometimes described as gently undulating. Beulah soils have been broadly mapped on multiple geomorphic features including old or abandoned Mississippi River meander belts, on floodplains of major tributaries (e.g., St. Francis River), remnant braid bars on interfluves of Late Pleistocene valley trains (Site F131AY204AR), and sand dunes in the Western Lowlands (Site F131AY102AR). The geomorphic features that correspond to the concepts of this ecological site are abandoned Mississippi River meander belts and active tributary floodplains, only.

The Bruno (sandy, mixed, thermic Typic Udifluvents) series consists of excessively drained soils that formed in sandy alluvium and thin strata of finer textures. These soils have rapid permeability with negligible runoff. Reaction ranges from strongly acid to slightly alkaline in the A horizon and strongly acid to moderately alkaline in the C horizon. Slopes range from 0 to 5 percent. Bruno soils have been mapped on multiple geomorphic features including old or abandoned Mississippi River meander belts, tributary floodplains, and remnant braid bars on interfluves of Late Pleistocene valley trains (Site F131AY204AR). The geomorphic features that correspond to the concepts of this ecological site are abandoned Mississippi River meander belts and active tributary floodplains, only.

The Crevasse (Mixed, thermic Typic Udipsamments) series consists of excessively drained soils that formed in sandy alluvium. Some pedons have loamy lenses or thin layers of very fine sandy loam or silt loam below a depth of 40 inches. These soils have rapid permeability with negligible runoff. The water table generally fluctuates between a depth of 3.5 to 6 feet during wetter periods of the year, typically winter and spring. Reactions range from moderately acid to moderately alkaline, and some pedons are calcareous. Slope gradients typically range from 0 to 5 percent. Crevasse soils generally form on sandy splays along levee breaks and recently deposited sediments on point bars of the Mississippi River and its tributaries. However, they have been more broadly mapped in the St. Francis Basin to include remnant braid bars on interfluves of Late Pleistocene valley trains (Site F131AY204AR) and locally on level to nearly level flood basins where they often occur in complex with very deep clayey soils (e.g., Sharkey series). In the latter, they are representative of sand blows that formed during the New Madrid earthquakes of 1811-1812 (USDA-SCS, 1971). The geomorphic features that most closely correspond to the concepts of this ecological site are more recent Mississippi River meander belts and tributary floodplains.

The Steele (sandy over clayey, mixed, superactive, nonacid, thermic Aquic Udifluvents) series consists of moderately well drained soils that formed in sandy and the underlying clayey river deposits. The upper part of the soil is rapidly permeable but this transitions to very slow permeability in the lower clayey horizons. During wet periods, these soils are saturated within 20 inches of the surface for several days. Thickness of the soil to the clayey substratum ranges from 20 to 36 inches. Reaction is medium acid to neutral in the sandy material and slightly acid or neutral in the clayey material. Slopes generally range from 0 to 5 percent. These soils have been mapped within meander belt environments, along narrow bands paralleling overflow channels, and locally on level to nearly level flood basins where they often occur in complex with very deep clayey soils (e.g., Sharkey series). Of note, Steele soils were formerly considered as inclusions in several soil series including the Bruno series of this site. They were viewed as deep overwashes of heavier soils such as Sharkey but could not be considered an overwash phase due to thickness exceeding 20 inches (Soil Survey Staff). However, caution should be exercised in viewing all occurrences of these soils as water deposited or overwash in origin. In some locations where Steele soils occur in complex with clayey soils such as Sharkey, their presence may represent eruptions or extrusions of coarse material (i.e., sand boils or sand blows) caused by tectonic forces during the New Madrid earthquakes of 1811-1812 (USDA-SCS, 1971).

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.

Figure 9. Profile of Crevasse fine sandy loam.

Table 4. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Fine sand (2) Fine sandy loam (3) Loamy fine sand (4) Loamy sand (5) Sandy loam
Drainage class	Moderately well drained to excessively drained
Permeability class	Very slow to very rapid
Soil depth	80 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (Depth not specified)	1.6 – 9.7 in
Calcium carbonate equivalent (Depth not specified)	Not specified
Electrical conductivity (Depth not specified)	1 mmhos/cm
Sodium adsorption ratio (Depth not specified)	Not specified
Soil reaction (1:1 water) (Depth not specified)	5.5 – 7.9
Subsurface fragment volume <=3" (40in)	2%
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). Today, this site is effectively disconnected from the Mississippi River via the vast network of constructed levees and, in many areas, local drainage controls. 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 and consideration.

This site was created by heavy deposition of coarse material. Where the site occurs on abandoned meander belts, overflow channels, and active floodplains, these sandy soils were mainly deposited during flood events. Secondarily, these soils formed as sand blows during the New Madrid earthquakes of 1811-1812 (USDA-SCS, 1971) where they often occur in complex with very deep clayey soils (e.g., Sharkey series).

By their nature, these coarse soils can have severe limitations on plant establishment, productivity, and survivorship. They are normally low in organic matter, available water holding capacity, and natural fertility. Yet, plants and plant communities are capable of establishment where moisture is available. Rooting depth to available moisture becomes critically important for survivorship, composition, and productivity. Notably, the soils often associated with sand blows and low areas within some meander belts and floodways are described as having sandy upper layers that are moderately deep (20 to 36 inches) to a clayey substratum (USDA-SCS, 1971). These depths are shallower compared to some of the soils deposited during flood events and available water capacity is moderate compared to the low capacity of more droughty, sandier alluvium.

Plant communities that develop on this site undergo dramatic changes over time. When these soils are first deposited, early colonizers primarily consist of eastern cottonwood and black willow or sandbar willow, if associated with sandbars and accreting point bars (Eyre, 1980). Although these rapidly permeable soils create limitations for many plant species, eastern cottonwood can survive and are capable of quickly dominating the site and forming even-aged stands (Putnam and Bull, 1932; Johnson and Shropshire, 1983; Hodges, 1997). Of note, stands exhibiting the best growth must have access to some level of moisture during the growing season (Williamson, 1913).

The eastern cottonwood forest type (Society of American Foresters, SAF, Type No. 63) is temporary on this site; it cannot regenerate under shade (Eyre, 1980). Natural “break up” of cottonwood stands may begin as early as 35 years after establishing, but by year 85, stands are transitioning to the next successional community, the eastern riverfront forest association (Meadows and Nowacki, 1996). Components of the succeeding forest typically include American sycamore, pecan, American elm, sugarberry, green ash, silver maple, and boxelder, although cottonwood may continue to persist as a minor component. The cover type generally recognized as representing the riverfront forest in the Mississippi River Valley is the American sycamore – pecan – American elm type, which is a variant of the American sycamore – sweetgum – American elm cover type (Society of American Foresters, SAF, Type No. 94; Eyre, 1980). Since this site, today, occupies abandoned river segments on the protected side of the constructed levee, additional components that are tolerant of these sandy soils may have filtered in including sweetgum and water oak.

One additional vegetation type may occur on this site locally in areas consisting of extremely deep sand deposits (dune-like features) that are prone to becoming very dry. These extreme environments are typed as “Mississippi River sandfield mixed herblands” in the Yazoo Basin, Mississippi (see MMNS, 2015). That community reportedly supports a diverse herbaceous layer that is dominated by brome (Bromus sp.), sixweeks fescue (Vulpia octoflora), and pricklypear (Opuntia sp.). Trees may occur but they generally represent a minor part of the community. Woody species reported include Chickasaw plum (Prunus angustifolia), eastern cottonwood, black willow, Hercules’ club (Zanthoxylum clava-herculis), honeylocust (Gleditsia triacanthos), red maple, buckthorn bully (Sideroxylon lycioides), green ash, American elm, false indigo bush (Amorpha fruticose), roughleaf dogwood (Cornus drummondii), and possumhaw (Ilex decidua).

Overall, natural cover types on this site are minor compared to other uses. Most areas have been cleared and are used extensively for production and other uses. Some areas have been land leveled 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

Ecosystem states

1. Sandy Bottomland Hardwoods

2. Cropland

3. Land Formed Cropland

4. Pastureland/Grassland

5. Forest Recovery

6. Conservation (Herbaceous)

States 2, 5 and 6 (additional transitions)

2. Cropland

5. Forest Recovery

6. Conservation (Herbaceous)

T1A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T1B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T2A	-	Precision land leveling
T2B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T2C	-	Natural succession (Community 5.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) and plant tree species appropriate for site (Afforestation - Community 5.2)
T2D	-	Establish select native species suitable for site; prepare for planting (herbicide and/or mechanical)
T4A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T4B	-	Natural succession (Community 5.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) for planting tree species appropriate for site (Afforestation - Community 5.2)
T4C	-	Establish select native species suitable for site and prepare area for planting (herbicide and/or mechanical).
T5A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T5B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T6A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation
T6B	-	Vegetation/stump removal (mechanical/chemical); seedbed preparation; establishment of desired forage; manage for grazing
T6C	-	Natural succession (Community 5.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) for planting tree species appropriate for site (Afforestation - Community 5.2).

State 1 submodel, plant communities

1.1. Dry Bottomland Hardwoods

State 2 submodel, plant communities

2.1. Conservation Management

2.2. Transitional Conservation Management

2.3. Conventional Management

2.1A	-	Soil disturbance (tillage); reduction of soil health.
2.1B	-	Conventional tillage, seeding, and fertility management for crops.
2.2A	-	No-till, cover crops, reduced till-soil health improvements.
2.2B	-	Conventional tillage, seeding, and fertility management for crops.
2.3A	-	Reduced till, no-till, and cover crops with soil health improvements as a goal.

State 3 submodel, plant communities

3.1. Land Leveled Cropland

State 4 submodel, plant communities

4.1. Monoculture Grassland

4.2. Mixed Species System

4.3. Mixed Species, Non-seeded

4.4. Early Woody Succession

4.1A	-	Seeding and/or management for desired species composition.
4.1B	-	Species management without overseeding.
4.2A	-	Seeding, fertilizing, management/removal of undesirable species.
4.2B	-	Species management without overseeding.
4.3A	-	Seeding, fertilizing, management/removal of undesirable species.
4.3B	-	Seeding and/or management for desired species composition.
4.3C	-	Lack of disturbance; no (or infrequent) mowing, herbivory, or brush management; natural succession of woody species.
4.4A	-	Brush management/removal of unwanted species.

State 5 submodel, plant communities

5.1. Ruderal/Opportunistic Regrowth

5.2. Afforestation

5.1A	-	Remove undesirable competitors; final soil preparation; establish site-appropriate species (favored in management).

State 6 submodel, plant communities

6.1. Pollinator Planting/Native Grasses

State 1
Sandy Bottomland Hardwoods

Removal of the historic natural communities of this site occurred long before thorough studies and investigations were conducted. Furthermore, the hydroperiod and drainage patterns of the landscape have since been dramatically altered. Great variability is likely to occur throughout the distribution of this ecological site. Local soils and hydrologic regimes will have been influenced by the environment they occur within, in addition to former land use histories. Such complexity across the area will likely be reflected in much variability in vegetation composition and structure of local stands (Stanturf et al., 2001). Accordingly, reference conditions for this site have yet to be confirmed, but they are perceived to consist of mature forest stands that support a diverse mix of southern bottomland hardwoods adapted to the moderately well to excessively drained soils of this site. Once assigned or identified, 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 forest ecology. 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 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 soil compaction (increased bulk densities), lower soil organic matter content, altered fertility, and smaller available rooting volume can reduce forest site productivity by 10 to 20 percent, if not more, 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 5 (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
Dry Bottomland Hardwoods

The reference community of this site may vary depending on the local environment. This site mainly includes former levee breaches and point bars (or meander scroll ridges) that have been protected from flooding for decades. Where the site occurs along active tributaries or stream systems, deposition may continue to occur during flood events. Plant composition and community structure under this scenario may be heavily influenced by the amount of material deposited, when the last major deposition occurred, flood velocity or scour, and pre-existing vegetation along the stream corridor or floodplain. Still, many of the same components of the meander belts will likely occur along stream corridors, although dominance and species abundances may vary. Following initial deposition, colonizing vegetation may be predominantly comprised of sandbar willow or black willow and eastern cottonwood. In areas where moisture is available, eastern cottonwood can rapidly assume dominance and establish itself in pure to nearly pure stands (Williamson, 1913; Eyre, 1980; Johnson and Shropshire, 1983; Meadows and Nowacki, 1996). Where this progression may be thwarted are in areas prone to sustained flooding giving advantage to the willow component (Eyre, 1980). The willow – cottonwood stand is short-lived with deterioration and breakup usually occurring within 35 to 85 years (Meadows and Nowacki, 1996). As canopy gaps from tree mortality and windthrow expand, the transition to the next community begins with openings occupied by the American sycamore – pecan – American elm type. Associates of the latter may include sugarberry, green ash, silver maple, boxelder, river birch, and red maple with occasional cottonwood stems persisting into the succeeding stand. In areas where disturbances are light and insignificant, additional species such as sweetgum and water oak may become established and replace some components in older stands of the sycamore-pecan-elm type. Areas that have been abandoned from the parent stream for many centuries may support components of Putnam’s (1951) “white oaks – red oaks – other hardwoods” forest type. However, it’s likely that only a subset of the species associated with the type can tolerate the driest locations, which may include bottomland post oak, white oak, southern red oak, sweetgum, hickory, blackgum, and winged elm. Species that may occur in locations with higher moisture content include cherrybark oak, water oak, swamp chestnut oak, willow oak, boxelder (Acer negundo), red maple (A. rubrum), sugarberry, American elm (Ulmus americana), American sycamore, and pecan (Broadfoot, 1976; Sharitz and Mitsch, 1993). Understory composition may be quite variable depending on the degree of canopy openings or overstory shade but may consist of seedlings and saplings of the preceding in addition to poison ivy (Toxicodendron radicans), grape (Vitis sp.), Virginia creeper (Parthenocissus quinquefolia), peppervine (Nekemias arborea), American buckwheat vine (Brunnichia ovata), greenbrier (Smilax sp.), trumpet creeper (Campsis radicans), blackberry (Rubus sp.), and giant cane (Arundinaria gigantea) (Eyre, 1980; Meadows and Nowacki, 1996).

State 2
Cropland

This state is representative of the dominant land use activity within the MLRA, agriculture production. The types of crops grown on this site will likely vary by soils and location. Some areas may remain “idle” or in a natural state due to extreme droughtiness. For those areas suitable for production, small grains such as grain sorghum (Sorghum bicolor) and wheat (Triticum aestivum) may be grown (USDA-SCS, 1990; USDA-NRCS, 2006b). It is possible that in areas with greater moisture additional crops may be suitable. Soil components of the Steele and Beulah series may support additional crops such as soybeans, cotton, and corn (Soil Survey Staff), but these are likely to occur as inclusions or within a much larger, wetter soil-site environment. The soils of this site have varying suitability for agriculture production. In general, Crevasse soils are poorly suited to row crops due to droughtiness. Beulah soils are generally productive and well suited for cropland if moisture is plentiful, but because of the low available water capacity, crops can be negatively impacted during dry periods. Bruno soils are typically considered poorly suited for cropland due to rapid permeability and very low to low available water capacity. Collectively, tilth of these soils is good with a surface layer that is very friable and easily tilled over a wide range of moisture content (USDA-SCS, 1990; USDA-NRCS, 2006b). Management concerns are largely centered on water management, availability, and need; erosion (including wind erosion); low to moderate organic matter content; crusting and packing following heavy rain; and the potential for plow pan development and soil compaction, particularly on Beulah and Steele soils. Each of these factors could affect yields or impede optimum operation. Management measures to ameliorate some of these issues may include implementing a water management strategy, a conservation tillage or management system, and 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 (Snipes et al., 2005). 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 2.1
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 site-specific practices to address conservation needs for a given location.

Community 2.2
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 site-specific practices to address conservation needs for a given location.

Community 2.3
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 2.1A
Community 2.1 to 2.2

Soil disturbance (tillage); reduction of soil health.

Pathway 2.1B
Community 2.1 to 2.3

Conventional tillage, seeding, and fertility management for crops.

Pathway 2.2A
Community 2.2 to 2.1

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

Pathway 2.2B
Community 2.2 to 2.3

Conventional tillage, seeding, and fertility management for crops.

Pathway 2.3A
Community 2.3 to 2.2

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

State 3
Land Formed Cropland

This gently sloping ecological site typically adjoins nearly level to level 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 2 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 3.1
Land Leveled Cropland

Some of the crop species and management practices indicated and discussed in State 2 (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 4
Pastureland/Grassland

This state is representative of areas that have been converted to and maintained in pasture or grassland. These sandy soils may be best suited to deep rooted perennial grasses, cool season reseeding legumes, and cool season annual forage plants. They may not be suited to tall fescue (Schedonorus arundinaceus) and dallisgrass (Paspalum dilatatum). Available water capacity is very low to low (USDA-SCS, 1990), which contributes to low forage production. Areas having strongly to moderately acid reactions may benefit from lime applications. However, reactions of Crevasse soils generally range from moderately acid to moderately alkaline; the need for lime may be location specific. Locations with a pH above 6.5 may be further limiting for some forage species like bahiagrass (Paspalum notatum), which generally responds poorly on neutral to alkaline soils (Houck, 2009). Given that this ecological site adjoins lower, wetter sites, some forage operations may utilize the higher elevations of this site as a protected area. This site may be suitable for the storage of harvested forage or holding of livestock when wet or flooded conditions occur on lower areas. 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 and 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 4.1
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 moderately 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.

Community 4.2
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.

Community 4.3
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 Bermudagrass and bahiagrass. 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 4.4
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 4.1A
Community 4.1 to 4.2

Seeding and/or management for desired species composition.

Pathway 4.1B
Community 4.1 to 4.3

Species management without overseeding.

Pathway 4.2A
Community 4.2 to 4.1

Seeding, fertilizing, management/removal of undesirable species.

Pathway 4.2B
Community 4.2 to 4.3

Species management without overseeding.

Pathway 4.3A
Community 4.3 to 4.1

Seeding, fertilizing, management/removal of undesirable species.

Pathway 4.3B
Community 4.3 to 4.2

Seeding and/or management for desired species composition.

Pathway 4.3C
Community 4.3 to 4.4

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

Pathway 4.4A
Community 4.4 to 4.3

Brush management/removal of unwanted species.

State 5
Forest Recovery

This state is representative of forest recovery in areas that were once under former intensive land use 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 tree and shrub species without management. Community phase 6.2 is representative of intentional forest establishment by artificial regeneration or 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 land use histories, having a clear understanding of the soil-site conditions is 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/or mechanical treatment) will most likely be critical. Post-planting operations and maintenance of the stand can enhance survival, future development, and achieve 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 summarization of the afforestation literature, techniques, and practices within the Southern Mississippi River Alluvium, interested parties are directed to Gardiner et al. (2002).

Community 5.1
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., elm, 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 winged elm, American elm, green ash, eastern cottonwood, American sycamore, sweetgum, red maple, and boxelder. Oaks that may occur in the young stand include bottomland post, southern red, cherrybark, willow, and water, but these will likely be rare or uncommon components, if present at all. 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 (Smilax spp.), eastern poison ivy, 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 rise to prominence in the stand.

Community 5.2
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 2) or it may be started following a fallow period (Community Phase 5.1). 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). 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 are favored in management (see State 1) may be appropriate for planting on this ecological site. However, Broadfoot (1976) listed a much narrower group of hardwoods suitable for planting on one of the soils of this site, Bruno soils, and they are sweetgum, eastern cottonwood, and American sycamore.

Pathway 5.1A
Community 5.1 to 5.2

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

State 6
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 6.1
Pollinator Planting/Native Grasses

This community phase represents the establishment of native forbs or wildflowers for pollinator habitat 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.), 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 big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium) and Indiangrass (Sorghastrum nutans). 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

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

Transition T1B
State 1 to 4

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 3

Precision land leveling

Transition T2B
State 2 to 4

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

Transition T2C
State 2 to 5

Natural succession (Community 5.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) and plant tree species appropriate for site (Afforestation - Community 5.2)

Transition T2D
State 2 to 6

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

Transition T4A
State 4 to 2

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

Transition T4B
State 4 to 5

Natural succession (Community 5.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) for planting tree species appropriate for site (Afforestation - Community 5.2)

Transition T4C
State 4 to 6

Establish select native species suitable for site and prepare area for planting (herbicide and/or mechanical).

Transition T5A
State 5 to 2

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

Transition T5B
State 5 to 4

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

Transition T6A
State 6 to 2

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

Transition T6B
State 6 to 4

Establish desired forage species and manage for grazing.

Transition T6C
State 6 to 5

Natural succession (Community 5.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) for planting tree species appropriate for site (Afforestation - Community 5.2).

Additional community tables

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

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Contributors

Barry Hart
Rachel Stout Evans

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	06/10/2025
Approved by	Charles Stemmans
Approval date
Composition (Indicators 10 and 12) based on	Annual Production