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Ecological site F131AY309MS

Yazoo - Recent Sandy Natural Levee and Meander Scroll Ridge Forest

Last updated: 6/10/2025
Accessed: 08/16/2026

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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., 2011).

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

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

LRU notes

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 Yazoo Basin.

The Yazoo Basin is in northwest Mississippi and is the largest tributary basin within MLRA 131A. The MLRA boundary of the basin extends some 200 miles (north to south) from Memphis, Tennessee to Vicksburg, Mississippi; is about 60 miles wide (east to west) at its widest point; encompasses roughly 7,600 square miles; and is bounded by the Loess Hills to the east and the current Mississippi River channel to the west (Saucier, 1994; Klimas et al., 2011). Elevations range from 210 feet in the northern portions of the basin to about 85 feet in the south near Vicksburg (Kirchner et al., 1992).

The basin’s geomorphic features are dominated by abandoned Mississippi River meander belts and backswamp environments. The higher elevations of natural levees and point bar deposits (meander scrolls) form an alluvial ridge, which directs local drainage and floodwaters to the intervening flood basins or backswamps. Additional meander belt landforms that are quite common include abandoned channels (oxbow lakes) and courses (Saucier, 1994; Klimas et al., 2011). A minor feature of the Yazoo Basin is the Pleistocene-age valley train terraces, which comprise less than 5 percent of the total area (Saucier, 1994).

The movement of water through the Yazoo Basin is heavily influenced and controlled by the complex sequence of abandoned Mississippi River meander belts and distributary channels. Most surface water originates as precipitation (Berkowitz et al., 2020) or runoff from the uplands to the east, which are conveyed by the Coldwater, Yocona, Tallahatchie, and Yalobusha rivers in addition to several smaller streams. These systems, along with streams draining the interior portions of the basin (e.g., Big Sunflower River, Bogue Phalia, and the distributary Deer Creek), all flow to the only significant outlet for the basin, the Yazoo River, which enters the Mississippi River near Vicksburg (Saucier, 1994; Klimas et al., 2011).

Historically, large floods on the Mississippi River and in the Yazoo tributary system inundated most, if not all, of the Yazoo Basin (Moore, 1972). These periodic floods and the ponding aftereffects oftentimes lasted for very long durations (Berkowitz et al., 2020), delivering nutrient-rich sediments that were critical to the production and maintenance of the dominant natural vegetation, bottomland hardwood forests (Taylor et al., 1990; MMNS, 2015). Since settlement, the biophysical environment of the area has been vastly altered. Perhaps the most notable change entails extensive modification of the basin’s natural hydrology, which includes hundreds of miles of constructed levees along the mainstem of the Mississippi River and basin tributaries; channel modifications on many streams; water control structures; land leveled areas; and an extensive network of surface drainage systems (Kirchner et al., 1992). Even with these measures, widespread backwater flooding occurs in the southern portion of the area (Yazoo Backwater Area) when high stages are reached on the Mississippi River. The extensive modifications to the basin’s hydrology coupled with increased access (Hudson, 1979) set the stage for broadscale conversion of former forestland to a variety of land uses with agriculture production being dominant. Today, bottomland hardwood forests cover roughly 10 percent of the original forest area (Smith and Klimas, 2002).

The geographic distribution of all ecological sites within the Yazoo Basin is bounded to the west by an extensive, mainline levee system. Throughout its length, the constructed levee generally occurs within the current Mississippi River meander belt and is situated to the east of the active river channel. All lands between the river channel and the constructed levee 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/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 (Chapman et al., 2004; Wiken et al., 2011)
- Mississippi River High Floodplain (Bottomland), CES203.196 (NatureServe, 2020)
- Cottonwood (Putnam and Bull, 1932)
- The following are hydrogeomorphic subclass, geomorphic setting, and potential natural vegetation association that dominantly coincides to or geometrically intersects the soil polygons of this ecological site (developed by Klimas et al., 2011): F1, High natural levees, Cottonwood – Water Oak – Sugarberry

Ecological site concept

The distribution of this ecological site is largely confined to the most recent meander belt of the Mississippi River. The soils that define the site formed in recent sandy alluvium. Within the meander belt environment, these very deep, excessively drained soils are initially deposited as sand splays along levee breaches and on point bars (convex bends) of the river. The geomorphic positions of this site, today, mainly include the high spots of natural levees and meander scroll ridge crests of abandoned river segments that were naturally separated from the main channel prior to construction of the mainline levee system. Additionally, the soils of this site have been mapped locally along a few active tributaries to the Mississippi River. Soil reactions range from moderately acid to moderately alkaline with some pedons exhibiting calcareous characteristics. Slopes of this site generally range from 0 to 5 percent. The natural vegetation of the site is greatly influenced by the frequency of disturbance, depositional environment, and proximity to moisture. Where ample moisture is available, newly formed ridges and splays are largely colonized by sandbar willow (Salix interior), black willow (S. nigra), and eastern cottonwood (Populus deltoides). As sites mature and the frequency of disturbance lessens, the pioneer stages succeed to a more diverse riverfront association that may include American sycamore (Platanus occidentalis), silver maple (Acer saccharinum), boxelder (A. negundo), American elm (Ulmus americana), pecan (Carya illinoinensis), sugarberry (Celtis laevigata), and sweetgum (Liquidambar styraciflua). Additional components may have filtered into this association where the site occurs on abandoned river segments as those areas have been protected from flooding by the constructed levee system for many decades.

Associated sites

F131AY310MS	Yazoo - Recent Loamy Natural Levee and Meander Scroll Ridge 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 (representing ecological site F131AY309MS) are deposited on and adjacent to the loamy natural levees and ridges of site F131AY310MS. Thus, the Recent Sandy Natural Levee and Meander Scroll Ridge Forest often forms a very close association with site F131AY310MS.
F131AY311MS	Yazoo - Recent Moderately Wet Natural Levee and Meander Scroll Ridge 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 (representing ecological site F131AY309MS) can occur on and adjacent to the somewhat poorly drained natural levee and meander scroll positions of site F131AY311MS.

F131AY310MS

Yazoo - Recent Loamy Natural Levee and Meander Scroll Ridge 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 (representing ecological site F131AY309MS) are deposited on and adjacent to the loamy natural levees and ridges of site F131AY310MS. Thus, the Recent Sandy Natural Levee and Meander Scroll Ridge Forest often forms a very close association with site F131AY310MS.

F131AY311MS

Yazoo - Recent Moderately Wet Natural Levee and Meander Scroll Ridge 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 (representing ecological site F131AY309MS) can occur on and adjacent to the somewhat poorly drained natural levee and meander scroll positions of site F131AY311MS.

Similar sites

F131AY407LA	Tensas Basin - Pointbars, Sandbars, and Splays This site consists of several similarities to the Yazoo - Recent Sandy Natural Levee and Meander Scroll site (F131AY309MS) including similar soils, landforms, and drainage characteristics. The principal difference is that F131AY407LA is situated in the Tensas Basin.
F131AY208AR	St. Francis - Sandy Natural Levee and Meander Scroll Forest This site supports similar soils and occurs on similar geomorphic features and positions as F131AY309MS. The principal difference is F131AY208AR occurs within the St. Francis Basin whereas the former is confined to the Yazoo Basin.
F131AY606MS	Batture - Frequently Flooded Pointbars, Sandbars, and Splays This site occurs on the same or similar geomorphic features as F131AY309MS. The principal difference is F131AY606MS occurs within the Batture, which is the area subjected to direct overflow from the active Mississippi River channel. Site F131AY309MS occurs on the protected side of the constructed levee.
F131AY305MS	Yazoo - Old Sandy Natural Levee and Meander Scroll Ridge Forest This site supports sandy soils that occur on similar geomorphic features as site F131AY309MS, but the sites differ dramatically in their ages and time periods of deposition. The soils of F131AY309MS are of recent origin (Crevasse soils), whereas the soils of F131AY305MS are much older, more weathered, and have reactions that can be slightly to strongly acid. Some locations have been abandoned by the parent stream for millennia. One characteristic that they have in common is that they both occur on the protected side of the constructed levee system.

Figure 1.

Table 2. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	Not specified

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Physiographic features

This ecological site is largely confined to the more recent meander belt of the Mississippi River. Within the meander belt environment, these very deep, excessively drained soils were initially deposited as sand splays along levee breaches and on point bars (convex bends) of the river. This site also occurs along tributaries to the river where former flood events led to heavy sand deposition and crevasse splays. On some landforms, such as meander scrolls, the terrain may have an undulating pattern – the characteristic “ridge and swale” topography – with soils of this site occupying the higher positions.

(The block diagram below is from East Carroll Parish, Louisiana, in the Tensas Basin and is included here to illustrate the general position of Crevasse soils relative to the surrounding soils and landscape.)

Figure 1. Block diagram from East Carroll Parish, LA. Crevasse soils are representative of this site.

Table 3. Representative physiographic features

Landforms	(1) Meander belt > Natural levee > Rise (2) Meander belt > Meander scroll > Rise
Runoff class	Very low to low
Flooding duration	Brief (2 to 7 days)
Flooding frequency	Very rare to frequent
Ponding frequency	None
Elevation	95 – 175 ft
Slope	0 – 7 %
Water table depth	57 – 60 in
Aspect	Aspect is not a significant factor

Climatic features

Climate of the Yazoo Basin is classified as Humid Subtropical (Koppen System), which is typified by mostly mild winters; long, hot and humid summers; and no routinely recurring wet or dry season (Smith and Klimas, 2002; NCDC, 2018). The average annual air temperature from 1980 through 2010 was 64 degrees F and the mean annual precipitation for the same period was 55 inches.

In the warmer season (and throughout much of the year), winds from the south convey moisture from the gulf leading to humid, semitropical conditions that are favorable for afternoon thunderstorms. These storms produce an average of about 25 percent 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. From 1980 through 2010, August and September were the driest months with a characteristic average monthly low of 2.5 and 2.8 inches, respectively. The hottest months of the year were July and August with characteristic average highs of 91 to 92 degrees and lows of around 72 degrees F.

In the colder season, the area’s weather is dominated by the positions of the Polar and Subtropical Jet Streams, both of which exerts 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 (NCDC, 2018). The coldest month of the year is typically January with an average monthly low and high of 33 and 52 degrees, respectively. The frost-free period from 1980 to 2010 averaged 207 days basin-wide and ranged from 200 days in the northern areas to 216 days in the south. Likewise, the freeze-free period averaged 241 days and ranged from 238 in the north to 246 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 of the basin. 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 June with March and April being the months of greatest frequency (NCDC, 2018). Precipitation for this period typically ranges from 4.5 to around 6.0 inches per month.

Table 4 Representative climatic features

Frost-free period (characteristic range)	200-220 days
Freeze-free period (characteristic range)	240-250 days
Precipitation total (characteristic range)	50-60 in
Frost-free period (actual range)	200-220 days
Freeze-free period (actual range)	230-250 days
Precipitation total (actual range)	50-60 in
Frost-free period (average)	210 days
Freeze-free period (average)	240 days
Precipitation total (average)	60 in

Characteristic range

Actual range

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Figure 2. Monthly precipitation range

Characteristic range

Actual range

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Figure 3. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 4. Monthly maximum temperature range

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Figure 5. Monthly average minimum and maximum temperature

Figure 6. Annual precipitation pattern

Figure 7 Annual average temperature pattern

Climate stations used

(1) LAKE PROVIDENCE [USC00165090], Lake Providence, LA
(2) CLEVELAND [USC00221738], Cleveland, MS
(3) CLEVELAND 3 N [USC00221743], Cleveland, MS
(4) MINTER CITY [USC00225897], Minter City, MS
(5) STONEVILLE EXP STA [USC00228445], Leland, MS
(6) CHARLESTON [USC00221606], Charleston, MS
(7) CLARKSDALE [USC00221707], Clarksdale, MS
(8) GREENVILLE [USC00223605], Greenville, MS
(9) MOORHEAD [USC00226009], Moorhead, MS
(10) GREENWOOD LEFLORE AP [USW00013978], Carrollton, MS
(11) LAMBERT 1W [USC00224869], Lambert, MS
(12) ROLLING FORK [USC00227560], Rolling Fork, MS
(13) BELZONI [USC00220660], Belzoni, MS
(14) TUNICA 2 N [USC00228998], Tunica, MS
(15) YAZOO CITY 5 NNE [USC00229860], Yazoo City, MS

Influencing water features

This site occupies the highest positions of recent natural levees and meander scroll ridges. The location or position of this site 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 to the Mississippi River. Those locations may receive overland flooding during heavy flood events. This site does not support obligate wetland species or exhibit hydric characteristics.

Soil features

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

This site is characterized by very deep, excessively drained soils that formed in recent sandy alluvium. A single soil series defines the site, which is the Crevasse (Mixed, thermic Typic Udipsamments) series. Crevasse soils generally form on sandy splays along levee breaks and recently deposited sediments on point bars of the Mississippi River and its tributaries. Reactions of these young soils range from moderately acid to moderately alkaline, and some pedons are calcareous. Slope gradients typically range from 0 to 5 percent.

Figure 8. Profile of Crevasse fine sandy loam.

Table 5. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Loamy sand (2) Sandy loam
Drainage class	Excessively drained
Permeability class	Rapid
Soil depth	80 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (Depth not specified)	2 – 3.6 in
Calcium carbonate equivalent (Depth not specified)	Not specified
Electrical conductivity (Depth not specified)	Not specified
Sodium adsorption ratio (Depth not specified)	Not specified
Soil reaction (1:1 water) (Depth not specified)	6.8 – 7
Subsurface fragment volume <=3" (40in)	0 – 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 primarily created by recent deposits of sandy material on levee breaks (i.e., sand splays) and on point bars of the Mississippi River and its tributaries. These younger deposits are distinguished from their much older sandy counterparts (see site ID: F131AY305MS) by having reactions that range from moderately acid to moderately alkaline and by lacking strata of finer sediments.

By their nature, these coarse, excessively drained 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 (USDA-SCS, 1961). Yet, plants and plant communities are capable of establishment where moisture is available.

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 is capable of quickly dominating the site and forming even-aged stands (Putnam and Bull, 1932; Johnson and Shropshire, 1983; Hodges, 1997). Notably, 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 (Quercus nigra).

One additional vegetation type may occur on this site 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 MMNS (2015). The community is reportedly comprised of 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 (Acer rubrum), 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

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T1A	-	Manipulate composition and manage for production (Community 2.1); heavy timber cutting or repeated partial harvests with no management (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 prepare area (plow pan breakup, fertilizing, etc.) and plant species appropriate for site (Afforestation - Community 6.2).
T3D	-	Establish select native species suitable for site; prepare for planting (herbicide and/or mechanical).
T5A	-	Vegetation/stump removal (mechanical/chemical); preparation for cultivation.
T5B	-	Natural succession (Community 6.1) or prepare area (plow pan breakup, fertilizing, etc.) and plant species appropriate for site (Afforestation - Community 6.2).
T5C	-	Establish select native species suitable for site; prepare 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 prepare area (plow pan breakup, fertilizing, etc.) and plant species appropriate for site (Afforestation - Community 6.2).

State 1 submodel, plant communities

1.1. Mixed Bottomland Hardwoods

State 2 submodel, plant communities

2.1. Forest Management

2.2. Non-managed/High-graded

2.1A	-	Cessation of management followed by heavy cutting or repeated partial harvests.
2.2A	-	Silvicultural treatments: removal of undesirable species; reestablish 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 heath 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: Sandy Riverfront Hardwoods

Removal of the pre-settlement natural communities of this site occurred long before thorough studies and investigations were conducted. Modifications to the Yazoo Basin’s natural hydroperiod and drainage patterns coupled with location-specific land use histories have further complicated species-site relationships. Such complexity across the Yazoo Basin will likely be reflected in much variability in vegetation composition and structure of local forest 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 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 return or transition pathway from the altered states (currently, only State 2) back to reference conditions is intended to represent the suite of hardwood species that, reportedly, frequently to occasionally occur and are favored in management on this site. 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 are challenges that may never be realized (Stanturf et al., 2001; Flinn and Vellend, 2005).

Community 1.1
Mixed 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 (Betula nigra), 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. 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; MMNS, 2015).

The Dominant Plant Species table below consists of components that are generally representative of areas where these soils are in close proximity to moisture. Extremely deep deposits of these sandy soils with "dune-like" appearances may be too droughty to support some of the species listed below.

Dominant plant species

eastern cottonwood (Populus deltoides), tree
black willow (Salix nigra), tree
American sycamore (Platanus occidentalis), tree
sugarberry (Celtis laevigata), tree
American elm (Ulmus americana), tree
red maple (Acer rubrum), tree
pecan (Carya illinoinensis), tree
silver maple (Acer saccharinum), tree
boxelder (Acer negundo), tree
possumhaw (Ilex decidua), shrub
roughleaf dogwood (Cornus drummondii), shrub
Chickasaw plum (Prunus angustifolia), shrub
buckthorn bully (Sideroxylon lycioides), shrub
Hercules' club (Zanthoxylum clava-herculis), 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 or diameter-limit 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 or trees of desirable species that are defective and fail to meet their maximum potential. (Because of the intensive management required to rehabilitate affected stands, this community phase warrants elevation to a standalone state. This should be considered in future iterations of this site’s development.)

This site is moderately suited for timber production. Limitations and management concerns are primarily due to droughty conditions of these sandy soils, which can increase seedling mortality. Approaches to help overcome these challenges include increase planting rates; controlling competing vegetation (particularly vines); maintaining a cover of mulch for moisture retention (USDA-SCS, 1990a); and planting seedlings in late winter to help aid in root establishment before the onset of hot, dry weather (USDA-SCS, 1990b). Where this site occurs in complex or contact with wetter ecological sites, seasonal wetness and periods of heavy precipitation can impose some limitations on heavy equipment usage. 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 land uses (alternate states) that result in altered conditions of the soil environment (e.g., land leveling) may deleteriously affect predicting and planning for species site selection, tree productivity, and possibly survival of the targeted species. State 6 (Forest Recovery) is representative of forest establishment and growth on locations where soil compaction and reduction of nutrients have occurred due to former land practices. 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 and long-term production and postproduction goals (Gardiner et al., 2002). However, before reaching the point of planning, it’s imperative to know whether a given location has the potential for supporting and producing a desired forest crop. Not every location having these excessively drained, coarse sandy soils (Crevasse series) are suited for forest production. Bull and Muntz (1943) warned against attempting to establish eastern cottonwood on locations they referred to as “…so sterile and dry that vegetation is sparse or lacking.” Locations where roots have access to moisture have the greatest potential for forest production on this site, including eastern cottonwood (Williamson, 1913).

Two major forest types potentially suited for this site are the eastern cottonwood and the American sycamore – pecan – American elm types. Eastern cottonwood is the fastest growing commercial forest species in eastern North America (Cooper and Van Haverbeke, 1990), and because of this attribute, it has been utilized in short pulpwood rotations (Cao and Durand, 1991) and in sawtimber operations (Johnson and Shropshire, 1983). Broadfoot (1960) listed a site index for eastern cottonwood growing on “dry phase” Crevasse soils as attaining 104 feet in 30 years growth. (This growth potential will vary on this soil-site environment. Note that "sand ridges" were excluded from Broadfoot’s sample due to excessive dryness.) Challenges to eastern cottonwood production are its extreme shade intolerance and its inability to cast dense shade over the understory. Due to shade intolerance, it cannot succeed itself naturally and requires mechanical site preparation (or scarification) to expose the soil surface prior to reestablishing. The relatively “light shading” that its canopy produces permits invasion of shade tolerant species. Many such stands may have dense midstories and understories of American sycamore, pecan, green ash, sugarberry, American elm, boxelder, silver maple, and occasionally sweetgum (Johnson and Shropshire, 1983; Hodges, 1995; Meadows and Stanturf, 1997) – all associates of the American sycamore – pecan – American elm type. In general, the latter will regenerate (and perpetuate) with most any regeneration method. For example, single-tree and small group selection harvests may favor proportionally more shade tolerant species of the type, while seed-tree and clearcuts tend to benefit shade intolerant taxa like pecan and American sycamore (Meadows and Stanturf, 1997).

Dominant plant species

eastern cottonwood (Populus deltoides), tree
American sycamore (Platanus occidentalis), tree

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 (i.e., 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 American elm, sugarberry, winged elm, boxelder, roughleaf dogwood, and possumhaw (Putnam et al., 1960).

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 (e.g., oaks). Continual competitor control will be needed.

State 3
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 location. Some areas may remain “idle” or in a natural state due to extreme droughtiness. For those areas that are suitable for being placed in production, small grains such as grain sorghum (Sorghum bicolor) and wheat (Triticum aestivum) may be grown (USDA-SCS, 1990b; USDA-NRCS, 2006b). It is possible that in areas with greater moisture additional crops may be grown. Such areas likely consist of smaller map unit polygons or inclusions of Crevasse soils within a much larger, wetter soil-site environment.

In general, Crevasse soils are poorly suited to row crops due to droughtiness. Properties contributing to limited use of these soils include rapid permeability, very low to low available water capacity, and low organic matter content and natural fertility (USDA-SCS, 1990a). Management concerns are largely centered on water management, availability, and need and poor retention of nutrients. The soil’s rapid permeability can leave irrigation efforts ineffective with very little moisture retention for plant uptake. Fertilizer (especially nitrogen) applications on these soils may be leached out rapidly. On a more local level, flooding may be problematic in some areas, and wind erosion can be a hazard if the soil is kept bare (USDA-SCS, 1990b). These factors could seriously affect yields or impede optimum operation. Management measures to ameliorate some of these issues may include a conservation tillage or management system that increases organic matter input. Tilth of these soils is easy to maintain with a surface layer that is very friable and easily tilled over a wide range of moisture content (USDA-SCS, 1990a). Major components that producers generally develop and plan are proper selection of crop cultivar, pest control, cropping system, tillage methods, and nutrient management in conjunction with 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, which are 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 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 gently sloping to undulating ecological site oftentimes adjoins nearly level to level landscapes. It is bordered by soils of varying textures and drainage characteristics. Accordingly, inconsistencies in wetness and dryness, ease of operation, and production or yields may occur across a cropped location. An increasingly common practice 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 the need for managing 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 systems. 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 sandy 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 areas that have been converted to and maintained in pasture or grassland. In 1991, the soils of this site were placed in Pasture Suitability Groups 3a (Crevasse soils) for the State of Mississippi. Crevasse soils are best suited to deep rooted perennial grasses, cool season reseeding legumes, and cool season annual forage plants. These sandy soils are not suited to tall fescue (Schedonorus arundinaceus) and dallisgrass (Paspalum dilatatum). Available water capacity is very low to low (USDA-SCS, 1990b), 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 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/or 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, although lime may not be needed in every location. Both bahiagrass and Bermudagrass (Cynodon dactylon) are typically well suited to sandy soils. However, areas with soil reactions above pH 6.5 are not suited to bahiagrass (Houck, 2009). Bermudagrass, though, has a broader range of pH tolerances, up to 8.5 (USDA-NRCS, 2000), and is well suited. 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

Bermudagrass (Cynodon dactylon), 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

Bermudagrass (Cynodon dactylon), grass
bahiagrass (Paspalum notatum), grass
perennial ryegrass (Lolium perenne ssp. perenne), grass

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. Commonly established species may include Bermudagrass (including the variety coastal 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 and/or grazing systems that allow for adequate rest and plant regrowth are required to maintain productivity. When forage species are afforded adequate recovery time between grazing intervals, they 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.

Dominant plant species

honeylocust (Gleditsia triacanthos), tree

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 (or 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 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 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. Depending on location, a profusion of growth may 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 pecan may not have an opportunity to colonize available areas due to distance and lack of a dependable dispersing agent (e.g., wildlife and water). 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 eastern cottonwood exclusively, if the stand began on bare mineral soils. Otherwise, the developing stand may be largely comprised of associates of the riverfront hardwoods including American sycamore, American elm, sugarberry, green ash, eastern cottonwood, sweetgum, silver maple, and boxelder. Problematic non-native species that may occur include Japanese honeysuckle (Lonicera japonica), Chinese privet (Ligustrum sinense), Chinese tallow (Triadica sebifera), 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 dominate the stand.

Dominant plant species

eastern cottonwood (Populus deltoides), tree
American sycamore (Platanus occidentalis), tree
elm (Ulmus), tree
sugarberry (Celtis laevigata), tree
silver maple (Acer saccharinum), tree
boxelder (Acer negundo), tree
trumpet creeper (Campsis radicans), shrub
eastern poison ivy (Toxicodendron radicans), shrub
greenbrier (Smilax), shrub

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 (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). A completely different approach must be taken if eastern cottonwood is the sole targeted species for planting. For eastern cottonwood, all potential competitors must be removed and the soil surface scarified via mechanical site preparation (Johnson and Shropshire, 1983; Hodges, 1995; Meadows and Stanturf, 1997). 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. Broadfoot and McKnight (1961) listed a narrower group of hardwoods suitable for planting on Crevasse soils including eastern cottonwood, American sycamore, pecan, green ash, and sweetgum. Of caution, afforestation attempts on this site are likely to be location specific due to the droughtiness and harsh conditions of many areas.

Dominant plant species

eastern cottonwood (Populus deltoides), tree
American sycamore (Platanus occidentalis), tree
pecan (Carya illinoinensis), tree
green ash (Fraxinus pennsylvanica), tree
sweetgum (Liquidambar styraciflua), tree

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 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

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 repeated partial harvests (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 reestablishment of missing species; the control or removal of exotic species (herbicide and mechanical); stand improvement practices that favors a return of more shade intolerant components, although a return to the pioneer state of eastern cottonwood may not be feasible.

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 prep area (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 area 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 prepare area (e.g., plow pan breakup, fertilizing, etc.) for planting tree species appropriate for site (Afforestation - Community 6.2).

Transition T5C
State 5 to 7

Establish select native species suitable for site and prepare area 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

Establish desired forage species and manage for grazing.

Transition T7C
State 7 to 6

Natural succession (Community 6.1) or prepare area (e.g., plow pan breakup, fertilizing, etc.) for planting tree 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

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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.

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Gardiner, E.S. and J.M. Oliver. 2005. Restoration of bottomland hardwood forests in Lower Mississippi Alluvial Valley, U.S.A. p. 235-251. In: J.A. Stanturf and P. Madsen (Editors). Restoration of Boreal and Temperate Forests. Boca Raton, FL: CRC Press.

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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	08/16/2026
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:

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Natural ResourcesConservation Service

Ecological site F131AY309MS

Yazoo - Recent Sandy Natural Levee and Meander Scroll Ridge Forest

Last updated: 6/10/2025 Accessed: 08/16/2026

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General information

MLRA notes

LRU notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Figure 1.

Table 2. Dominant plant species

Natural Resources
Conservation Service

Last updated: 6/10/2025
Accessed: 08/16/2026