CHAPTER IV: WILDLIFE HABITATS FOR MISSISSIPPI’S SGCN,

THREATS AND CONSERVATION ACTIONS^139

R iverfront soils are lower in organic matter and have higher pH than soils of other bottomland

hardwoods. New soils in accretion zones range from fine clay to coarse sand, depending on flow

velocities at the time of sediment deposition. Backwater areas contain finer textured substrates and

point bars are sandier. The moisture level of riverfront substrates depends on river stage, which is

usually high in the spring, causing saturation or flooding, and low in the fall, bringing dryer conditions.

Flooding along the riverfront areas reworks sediments from river banks, sandbars and point bars to form

new channels, submerging some areas and building new lands elsewhere. Wet exposed mineral soils

provide open habitats for cottonwood and willow to germinate. The dominant trees of these areas

germinate best in exposed mineral soil, grow rapidly once river levels fall and must tolerate submersion

and sediment accumulation. Sedimentation degrades aquatic habitats and kills aquatic organisms,

including fish. Riverfront forests, which control shoreline erosion and intercept eroded soil from upland

areas, effectively reduce the amount of sediment reaching rivers and streams.

This type includes two subtypes: 5.1 Cottonwood/Black Willow/River Birch Woodlands, and 5.2

Sandbars.

GENERAL CONDITION:

Dams, channelization, manmade levees and other modifications have restricted the extent of riverfront

forests. Bank erosion-accretion process has been slowed or eliminated along leveed and stabilized

portions of the Mississippi River. The modified river environment has inhibited riverfront cottonwood

and willow community regeneration.

Although much diminished after river diking, dredging, revetment and channelization projects, the lands

between the Mississippi River and its levees still contain the long swaths of riverfront forests. It is

estimated that over 500,000 acres of cottonwood-willow forest remains in the Lower Mississippi River

alluvial plain within Mississippi, Arkansas and Louisiana. Rivers confined to the western portion of the

state and flow into the Mississippi River, such as the Big Black and Sunflower, are dramatically

impacted by the stages of the Mississippi River, which significantly alters their rate of flow and

sediment deposition.

Sandbars are dynamic lotic features that generally persist in the presence of many human activities.

5. RIVERFRONT PALUSTRINE (MOIST)

FLOODPLAIN FORESTS/HERBLANDS/SANDBARS