The Special Landscape of West Tennessee
The Coastal Plains of West Tennessee are unlike the mountainous regions of middle and East Tennessee. Vast areas of bottomland hardwood wetlands provide important habitats for migrating waterfowl and other birds, while maintaining a diversity of fishes (130 species) adapted to life in a the slow-moving, sandy waters. Cypress and tupelo trees dominate the bottomlands while upland forests range from mixed oak and pine forest to oaks and hickories. West Tennessee is the state’s most active agricultural region with productive fields of corn, cotton and soybeans.
In the early 20th century and into the 1970s there was a push to drain many of the natural bottomlands in an effort to reduce flooding. Local drainage districts and federal agencies began channelizing nearly every stream and river in the region, with the exception of the mainstems of the Hatchie River and Wolf River. Channelization involved abandoning the old river course and digging a new channel that was wider, straighter, deeper and of higher slope. The idea was to move water off of the landscape as swiftly as possible. As wetlands were drained, much land was cleared of timber and converted to cropland. These new croplands were protected by levees built from the spoils of the channel excavation. Though these efforts were initially successful at improving drainage, they have now in many circumstances caused or exacerbated the very problems they intended to address.
The Nature Conservancy works on many unique conservation challenges in West Tennessee. Channelization not only permanently altered stream habitats but also caused an increase in channel incision that still occurs. Channels that incise (i.e., erode their bed) degrade habitats and cause such severe sediment loading that entire streams can be lost in a valley plug. A valley plug is a large accumulation of sediment that blocks the flow of a stream. Valley plugged areas increase flooding since channels disappear and also cause tree mortality as the valleys can fill with several feet of sediment. The channelization of streams and rivers alters physical habitats important to invertebrates and fishes. Agricultural production has improved greatly through adoption of no-till production techniques, but due to our extremely erodible soils excess nutrient and sediment loading is still problematic.
Fighting the Dead Zone in the Gulf of Mexico
The Nature Conservancy is undertaking a bold strategy to help fix the "dead zone" in the Gulf of Mexico. In a multi-state effort, the Conservancy aims to reduce the influx of nitrogen and phosphorus, also known as nutrients, into the Mississippi River by 20 percent. In doing so, we aim to shrink the size of the Gulf's dead zone from its current average of 5,220 square miles to 2,000.
Tennessee's contribution to nutrient loading in the Mississippi comes partly from agricultural runoff. Much of our stream and river work in West Tennessee is intended to reduce erosion and sedimentation, which reduces nutrient loading and improves habitats. Read more about these efforts in this newsletter cover story.
Why The Nature Conservancy Works in West Tennessee
The ecologically distinct lands and waters of West Tennessee provide a number of unique habitat types for fish and wildlife that are not found anywhere else in the state. Additionally, the Mississippi River and its floodplains are recognized across our organization as a conservation priority. The Nature Conservancy has focused on conservation of the biologically rich Hatchie River, the longest unchannelized river in the region, since the 1980s.
While West Tennessee has areas of protected land, including state parks, state natural areas, federal parks and federal refuges, there remain many crucial conservation opportunities to pursue. These include protecting habitat zones in between previously protected areas, restoring bottomland hardwood forests and continuing stream restoration efforts, which can ultimately improve water quality and habitat all the way to the Gulf of Mexico.
Though modification of the landscape is widespread, the region supports a diversity of animals, including 130 species of fish, 50 species of mammals, 45 species of reptiles and amphibians and 37 species of freshwater mussels. Approximately 60 percent of bird species in the continental United States use this ecoregion, either as permanent habitat or as part of their migration route. In addition, the bottomland hardwood forests of this region are among the most productive bird-nesting areas in the United States. West Tennessee also supports the greatest variety of reptiles in the state.
Due to flood control practices and other dramatic alterations to the landscape over the past two hundred hears, only 4.4 million acres of bottomland hardwood forest remain in this ecoregion, equivalent to 20 percent of the forest's original extent. Decades-old channel alterations (channelization), particularly in the Obion and Forked Deer river systems have significantly limited aquatic habitat in the region. Excessive siltation associated with increased runoff and streambank erosion continue to pose threats to the ecological integrity of West Tennessee.
The West Tennessee River Basin Authority
Learn about our important partners in West Tennessee conservation.