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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 Riverfront Forest.
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 Riverfront Bottomland Forest.
National Vegetation Classification System Vegetation Association (NatureServe, 2010):
The reference state for this ecological site is most similar to a Fraxinus pennsylvanica - Ulmus americana - Celtis laevigata / Ilex decidua Forest (CEGL002427).
Geographic relationship to the Missouri Ecological Classification System (Nigh & Schroeder, 2002):
This Ecological Site occurs within several Land Type Associations of the Mississippi River Alluvial Plain Subsection.
Ecological site concept
Loamy Floodplain Step Forests are within the green areas on the map (Missouri portion only; distributions farther south are currently under review). Sites are locally abundant near the current Mississippi River channel, in Scott and Mississippi counties, Missouri, with a few scattered areas to the south. Soils are very deep and loamy. The reference plant community is forest dominated by American elm, hackberry and green ash, with scattered sycamore and sweetgum.
Table 1. Dominant plant species
Tree (1) Ulmus americana
(2) Celtis occidentalisShrub (1) Vitis
Herbaceous (1) Carex
(2) Laportea canadensis
