Natural Resources
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Major Land Resource Area or ecological site by name and/or ID.
General information
Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
MLRA notes
Major Land Resource Area (MLRA): 131A–Southern Mississippi River Alluvium
The Southern Mississippi River Alluvium (outlined in red on the map; northern portion only) is a vast alluvial plain, stretching from the confluence of the Mississippi and Ohio Rivers to tidewater areas of the Gulf of Mexico. The area is formed primarily in sediments deposited by the Mississippi River, with significant contributions from the St Francis and Black Rivers west of Crowley’s Ridge, in the northern part of the area. A variety of alluvial landforms are present, including natural levees, sand splays, backswamps, channels, swales, stream terraces and braided terraces. Dunes have formed from wind redistribution of alluvial sands, and loess deposits overlie older terraces to the west. Elevation ranges from about 330 feet in the north to sea level in the south. Local relief is low, and much of the area appears flat, although low escarpments and other slight changes in elevation often indicate major changes in hydrology and soils.
Classification relationships
Terrestrial Natural Community Type in Missouri (Nelson, 2010):
The reference state for this ecological site is most similar to a Bottomland Flatwoods.
Missouri Department of Conservation Forest and Woodland Communities (Missouri Department of Conservation, 2006):
The reference state for this ecological site is most similar to a Bottomland Woodland.
National Vegetation Classification System Vegetation Association (NatureServe, 2010):
The reference state for this ecological site is most similar to a Quercus palustris - (Quercus stellata) - Quercus pagoda / Isoetes spp. Forest (CEGL002101).
Geographic relationship to the Missouri Ecological Classification System (Nigh & Schroeder, 2002):
This Ecological Site occurs primarily within the Otter Slough Silty Terrace Land Type Association of the Black River Alluvial Plain Subsection.
Ecological site concept
Natric Terrace Flatwoods are within the green areas on the map (Missouri portion only; distributions farther south are currently under review). These sites are not extensive, occurring west of Crowley’s Ridge near the St. Francis River. Soils are affected by excess sodium, and are alkaline. The reference plant community is woodland with an overstory dominated by post oak and southern red oak, an open understory of possum haw and swamp privet, and a variable ground flora with dense patches of sedges.
Table 1. Dominant plant species
Tree (1) Quercus stellata
(2) Quercus falcataShrub (1) Rosa carolina
Herbaceous (1) Carex
(2) Sorghastrum nutans
