![]() The Northern Holocene Meander Belts ecoregion is a flat to nearly flat floodplain containing the meander belts of the present and past courses of the Mississippi River. Level IV ecoregions Northern Holocene Meander Belts (73a) Small to medium size earthquakes still occur frequently their shocks are magnified by the alluvial plain's unconsolidated deposits, creating regional land management issues. Earthquakes in the early nineteenth century offset river courses in Ecoregion 73. Batture lands are hydrologically linked to the Mississippi River, flood-prone, and contain remnant habitat for “big river” species (e.g., pallid sturgeon) as well as river-front plant communities they are too narrow to map as a separate Level IV ecoregion. Between the levees that parallel the Mississippi River is a corridor known as the batture lands. Man-made flood control levees typically flank the Mississippi River and, in effect, separate the river and its adjoining habitat from the remainder of its natural hydrologic system in so doing, they interfere with sediment transfer within the region and have reduced available habitat for many species. Fish communities in least altered streams typically have an insignificant proportion of sensitive species sunfishes are dominant followed by minnows. Concentrations of total suspended solids, total dissolved solids, total phosphorus, ammonia nitrogen, sulfates, turbidity, biological oxygen demand, chlorophyll a, and fecal coliform are high in the rivers, streams, and ditches of the region they are often much greater than elsewhere in Arkansas, increase with increasing watershed size, and are greatest during the spring, high-flow season. Presently, most of the northern and central sections are in cropland and receive heavy treatments of insecticides and herbicides soybeans, cotton, and rice are the major crops, and aquaculture is also important.Īgricultural runoff containing fertilizers, herbicides, pesticides, and livestock waste have degraded surficial water quality. The Mississippi Alluvial Plain has been widely cleared and drained for cultivation this widespread loss or degradation of forest and wetland habitat has impacted wildlife and reduced bird populations. ![]() Potential natural vegetation is largely southern floodplain forest and is unlike the oak–hickory and oak–hickory–pine forests that dominate uplands to the west in Ecoregions 35, 36, 37, 38, and 39 loblolly pine, so common in the South Central Plains (35), is not native to most forests in the Arkansas portion of Ecoregion 73. It is also a major bird migration corridor used in fall and spring migrations, known as the Mississippi Flyway. The ecoregion provides important habitat for fish and wildlife, and includes the largest continuous system of wetlands in North America. Many reaches have ill-defined stream channels. Streams and rivers have very low gradients and fine-grained substrates. Nearly flat, clayey, poorly-drained soils are widespread and characteristic. ![]() River terraces, Swales, and levees provide limited relief, but overall, it is flatter than neighboring ecoregions in Arkansas, including the South Central Plains. It is veneered by Quaternary alluvium, loess, glacial outwash, and lacustrine deposits. It is a broad, nearly level, agriculturally-dominated alluvial plain. The Mississippi Alluvial Plain extends along the Mississippi River from the confluence of the Ohio River and Mississippi River southward to the Gulf of Mexico temperatures and annual average precipitation increase toward the south. The Mississippi Alluvial Plain ecoregion has been subdivided into fifteen Level IV ecoregions. It parallels the Mississippi River from the Midwestern United States to the Gulf of Mexico. states, though predominantly in Arkansas, Louisiana, and Mississippi. ![]() The Mississippi Alluvial Plain is a Level III ecoregion designated by the Environmental Protection Agency (EPA) in seven U.S.
0 Comments
Leave a Reply. |