Mississippi Alluvial Valley Forests

The next 50 years

Range and extent of the Mississippi Alluvial Valley (red outline) and the counties it encompasses (white outlines). The yellow line separates the Holocene Deposits section from the Deltaic Plain section. Photo courtesy of the U.S. Forest Service.
Range and extent of the Mississippi Alluvial Valley (red outline) and the counties it encompasses (white outlines). The yellow line separates the Holocene Deposits section from the Deltaic Plain section. Photo courtesy of the U.S. Forest Service.

The Southern Forest Futures Project (SFFP) started as an effort to study and understand the various forces reshaping the forests across the 13 states of the Southeast. Chartered by the U.S. Forest Service Southern Region and Southern Research Station (SRS) along with the Southern Group of State Foresters, the project examined a variety of possible futures and how they might affect forests and their many ecosystems and values.

Because of the great variations in forest ecosystems across the South, the Futures Project produced separate findings and implications for each of five subregions, including a report on the Mississippi Alluvial Valley, a 24.9-million-acre area in the floodplain and delta of the lower Mississippi River.

“This report identifies findings from the Futures Project relevant to the Mississippi Alluvial Valley and expands those findings further through additional synthesis and analysis,” said Emile Gardiner, author of the report and research forester for the SRS Center for Bottomland Hardwoods Research. “It also outlines implications of the alternative futures developed for the Futures Project for the forest-based resources and ecosystem services of the Mississippi Alluvial Valley.”

The Mississippi Alluvial Valley, subdivided for the report into an upper Holocene Deposits section and a lower Deltaic Plain section, supports a robust agricultural economy and provides significant recreational resources to residents of nearby urban centers. Although forests make up only 28 percent of the subregion, the bottomland forests and coastal swamps of the area provide habitat for diverse plants and animals, produce valuable forest products, and provide innumerable ecosystem services, including water quality and flood mitigation.

A few of the many key findings included in the report:

  • Average annual temperatures within the Mississippi Alluvial Valley are projected to rise by 1.2 to 2.9 °C through 2060, while average annual precipitation is forecasted to decrease by 1 to 24 percent during the same period.
  • Deforestation will continue in the Mississippi Alluvial Valley, but future clearing will be driven not by agricultural development but by urbanization, which is expected to drive the largest shift in land use over the next 50 years.
  • Nonnative insects and diseases will likely create more forest health issues within the Mississippi Alluvial Valley within the next 50 years. Once established in the area, emerald ash borer and other specialized nonnative insect pests could cause acute damage and the widespread elimination of their host trees.
  • Coastal baldcypress-water tupelo swamps of the Deltaic plain section are vulnerable for nearly complete degradation and loss from urbanization as well as altered hydrologic and sediment regimes, land subsidence, and sea-level rise.
  • As many as 21 high-priority nonnative plants now cover over 3.1 percent (206,782 acres) of all the area’s forests. Japanese honeysuckle, at 112,000 acres, is the most pervasive nonnative plant, and tallowtree (occupying 37,000 acres) the most widespread and abundant nonnative tree.
  • The area experiences a low incidence of wildfire compared to the rest of the South, but forecasted shifts towards a hotter and dryer climate through 2050 raise the potential for wildfire in the upper Holocene Deposits section, particularly in Arkansas.

For more findings and analyses, access the full text of the report.

For more information, email Emile Gardiner at egardiner@fs.fed.us.

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