Natural Resources
Conservation Service
-
Search
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 Wet-Mesic Bottomland 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 Wet Bottomland Forest.
National Vegetation Classification System Vegetation Association (NatureServe, 2010):
The reference state for this ecological site is most similar to a Quercus phellos - (Quercus lyrata) / Carex spp. - Leersia spp. Forest (CEGL002102).
Geographic relationship to the Missouri Ecological Classification System (Nigh & Schroeder, 2002):
This Ecological Site occurs primarily in the following Subsections:
Mississippi River Alluvial Plain
St. Francis River Alluvial Plain
Ecological site concept
Wet Braided Terrace Forests are within the green areas on the map (Missouri portion only; distributions farther south are currently under review). These sites are widely distributed on braided stream terraces and floodplains throughout the area, especially east of Crowley’s Ridge. They are closely associated with Braided Terrace Channel ecological sites. Soils are very deep with seasonal high water tables. The reference plant community is forest dominated by willow oak, sweetgum, pin oak, Nuttall oak, water oak, American elm, sugarberry, and green ash.
Table 1. Dominant plant species
Tree (1) Liquidambar styraciflua
(2) Quercus phellosShrub (1) Ilex decidua
Herbaceous (1) Carex
(2) Impatiens pallida
