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South-Central Interior Wet Flatwoods

EVT 7457South-Central Interior / Upper Coastal Plain Wet Flatwoods

CES203.480GNRTreeRiparian

Summary

This system represents predominantly wet flatwoods of limited areas of the most inland portions of the East Gulf Coastal Plain in western Kentucky, as well as related broad, flat areas of the western Interior Low Plateau. This part of the Coastal Plain is referred to as the Jackson Purchase or "Jackson Plain." They tend to be confined to relatively small areas near the eastern flank of the region where loess deposits thin out. Unlike South-Central Interior / Upper Coastal Plain Flatwoods (CES203.479) of the same general region (which is typified by complex microtopography), this system occupies broad flats underlain by fragipans. These fragipans impede the downward migration of water, resulting in wet conditions for portions of the year. Fire was important, probably maintaining relatively open-canopied stands. Stands are dominated by hardwood trees, including Acer rubrum, Fagus grandifolia, Liquidambar styraciflua, Quercus falcata, Quercus pagoda, and Quercus palustris.

Source: NatureServe Explorer

Vegetation

Stands are typically dominated by various combinations of oaks and other hardwoods, including Quercus pagoda, Quercus stellata, Carya ovata, Prunus serotina, Diospyros virginiana, Ulmus alata, Ulmus americana, Quercus palustris (Bryant 1999), Quercus michauxii, Liquidambar styraciflua, Carya spp., Nyssa sylvatica, and Acer rubrum (Chester et al. 1995). Most stands of this system have been severely altered or destroyed, and the characteristic herbs are poorly known. Campsis radicans may be found, along with Carex spp., including Carex leptalea and Carex cherokeensis. Other herbs may include Leersia spp. and Cardamine bulbosa. Quercus phellos and/or Quercus lyrata may also be present in stands of this system in Kentucky (M. Evans pers. comm. 2006). Some stands placed here are dominated by Quercus falcata (e.g., at Shiloh National Military Park), others (e.g., in the Moulton Valley of Alabama) by a combination of Quercus phellos and Quercus nigra (A. Schotz pers. comm. 2006).

Source: NatureServe Explorer

Environment

These flatwoods have long been recognized as the primary vegetation type of a distinctive subdivision within the Upper East Gulf Coastal Plain region (Davis 1923, Bryant and Martin 1988), as well as related areas of the western Interior Low Plateau. Within the "Jackson Plain" portion of the Upper East Gulf Coastal Plain, these flatwoods tend to be confined to relatively small areas near the eastern flank of the "Jackson Plain" region where the loess deposits thin out. Like drier Quercus stellata flatwoods of these areas (which are typified by microtopographic variation), this system occupies broad flats underlain by fragipans. These fragipans impede the downward migration of water resulting in wet conditions for longer portions of the year. In the Jackson Plain area the soils include Henry silt loam, Routon silt loam (Bryant and Held 2001) and Calloway silt loam (Karathanasis et al. 2003). Fire is probably relatively infrequent in this system (M. Evans pers. comm.). In the Pennyroyal Plain, this system occurs on upland flats and depressions with poor drainage, underlain by limestone; soils include Robertsville silt loam (Chester et al. 1995) and Henry silt loam (M. Evans pers. comm.).

Source: NatureServe Explorer

Dynamics

Fire was an important but relatively infrequent natural process in this system, probably maintaining relatively open-canopied stands (M. Evans pers. comm.). Under such conditions Andropogon gerardii and Chasmanthium spp. may have dominated the herbaceous ground cover. Flooding and saturation are part of the natural dynamics. Due to the fragipan, deep rooting of trees is limited and the trees are particularly prone to windthrow during storms. This has helped maintain open woodland conditions.

Source: NatureServe Explorer

Threats

Threats include clearing, conversion and drainage for agriculture. Most historic occurrences have been cleared, drained and tiled, and remaining sites are small, isolated and degraded. Fragmentation and lack of fire are also threats. Invasive shrubs Ligustrum sinense, Lonicera maackii, vine Lonicera japonica, and grasses Microstegium vimineum and Arthraxon hispidus are threats. Tiling since the 1960s has contributed to the drainage of sites which previously were considered too wet to farm. Logging of oaks and hickories can lead to succession to wet forests dominated by ruderal trees, such as Acer rubrum and Liquidambar styraciflua and invasive exotic plants in the shrub and herbaceous vegetation layers.

Source: NatureServe Explorer

Distribution

The primary range of this system is limited areas of the "Jackson Purchase" or "Jackson Plain" of Kentucky and possibly related areas in adjacent western Tennessee, as well as related broad, flat areas of the western Interior Low Plateau. Examples in the Pennyroyal Plain (of the western Interior Low Plateau) have been known for many years and referred to as "pondywoods" or "crawfishy land" (Chester et al. 1995). They are also known from the Shawnee Hills of Kentucky, on periglacial lakebeds (M. Evans pers. comm. 2006), and related wet flatwoods have been discerned from wetland modeling and confirmed in the Moulton Valley of Alabama (A. Schotz pers. comm. 2006) and are included here. It is assumed to cross the Ohio River into adjacent Indiana.

Source: NatureServe Explorer

Ecologically Associated Plant Species

Plant species that characterize this ecosystem type, organized by vegetation stratum. These are species ecologically associated with the ecosystem, not confirmed present in any specific area.

Tree canopy

Acer rubrum, Carya ovata, Diospyros virginiana, Liquidambar styraciflua, Nyssa sylvatica, Prunus serotina, Quercus falcata, Quercus lyrata, Quercus michauxii, Quercus nigra, Quercus pagoda, Quercus palustris, Quercus phellos, Quercus stellata, Ulmus alata, Ulmus americana

Herb (field)

Campsis radicans, Cardamine bulbosa, Carex cherokeensis, Carex leptalea

Source: NatureServe Ecological System assessment

Ecologically Associated Animals (4)

Animal species ecologically associated with this ecosystem type based on NatureServe assessment. These are species whose habitat requirements overlap with this ecosystem, not confirmed present in any specific roadless area.

Mammals (1)

Common Name	Scientific Name	G-Rank
Southeastern Shrew	Sorex longirostris	G5

Reptiles (2)

Common Name	Scientific Name	G-Rank
Red-bellied Mudsnake	Farancia abacura	G5
Dekay's Brownsnake	Storeria dekayi	G5

Amphibians (1)

Common Name	Scientific Name	G-Rank
Mole Salamander	Ambystoma talpoideum	G4G5

Source: NatureServe Ecological System assessment

Component Associations (3)

Plant community associations that occur within this ecological system. Associations are the finest level of the U.S. National Vegetation Classification (USNVC) and describe specific, repeating assemblages of plant species. Each association represents a distinct community type that may be found where this ecosystem occurs.

Name	G-Rank
Quercus falcata Wet Flatwoods Forest	G2	NatureServe
Quercus palustris - (Quercus stellata) - Quercus pagoda / Isoetes spp. Wet Forest	G2	NatureServe
Quercus phellos - (Quercus lyrata) / Carex spp. - Leersia spp. Pond Forest	G3	NatureServe

State Conservation Ranks (3)

Subnational conservation status ranks (S-ranks) assigned by Natural Heritage Programs in each state where this ecosystem occurs. S1 indicates critically imperiled at the state level, S2 imperiled, S3 vulnerable, S4 apparently secure, and S5 secure. An ecosystem may be globally secure but imperiled in specific states at the edge of its range.

State	S-Rank
AL	SNR
KY	SNR
TN	SNR

Methodology and Data Sources

Ecosystem classification: Ecosystems are classified using the LANDFIRE 2024 Existing Vegetation Type (EVT) layer, mapped to NatureServe Terrestrial Ecological Systems via a curated crosswalk. Each EVT is linked to the USNVC (U.S. National Vegetation Classification) hierarchy through pixel-level co-occurrence analysis of LANDFIRE EVT and NatureServe IVC Group rasters across all roadless areas.

Vegetation coverage: Coverage percentages and hectares are derived from zonal statistics of the LANDFIRE 2024 EVT raster intersected with roadless area boundaries.

Ecosystem narratives and community species: Sourced from the NatureServe Explorer API, representing professional ecological assessments of vegetation composition, environmental setting, dynamics, threats, and characteristic species assemblages.

IVC hierarchy: The International Vegetation Classification hierarchy is sourced from the USNVC v3.0 Catalog, providing the full classification from Biome through Association levels.

Component associations: Plant community associations listed as components of each NatureServe Ecological System. Association data from the NatureServe Explorer API.

State ranks: Conservation status ranks assigned by NatureServe member programs in each state where the ecosystem occurs.