Impact of Tree “Dead Zones” Along Mississippi River Shores

Shown is an area along the shores of the Mississippi River with complete loss of trees which causes a decline in ecosystem biodiversity. The river at the time of the picture is at flood stage — 13 feet. In these dead zones, most of the tree loss is due to long lasting flooding, or multiple floods throughout the year that stress the old-growth trees to the point they can no longer survive. The use of dams to control the shipping lanes and the use of levees along the Mississippi to protect homes, farmland, and business keep floodwaters in a contained area in which would normally spread out. This results in river levels rising higher and lasting longer than they otherwise would. These longer periods of flooding increase stress and death of native species of trees, decreasing the habitat for other native species. The U.S.. Army Corps of Engineers have been performing timber inventories to see what species of plants are currently in the different forests, doing tree plantings of different species of native wetland trees, and tree cutting to try to help new growth trees survive and mature. The Corps has also been doing dredge placements on certain islands to try and build them up, and replanting new trees to see if building up an island will help support the growth of a forest.

• How can we reduce the effects of tree death and stabilize ecosystems along the Mississippi due to human impacts?

• How do you think the loss of trees will impact the native animal species in this area?
• How can we reduce the human impact to these areas while maintaining our infrastructure and economy?
• What actions can be put in place to bring these areas back, reduce the loss of biodiversity and prevent this from happening again?

Students could:

• Research what species of wetland trees are more flood tolerant.
• Look for trends in the flooding along the Mississippi for the last 5-10 years.
• Divide into groups to create a solutions-based project.

• U.S. Army Corp of Engineers | Upper Mississippi River Restoration (UMRR): This website has information on current and past restoration projects along the upper Mississippi.
• Geographic Information System (GIS) of Iowa: This website has maps of Iowa, and different filters that can be used to look at ground cover, elevation, and previous photos of tree cover in an area.
• U.S. Geological Survey | A Brief History and Summary of the Effects of River Engineering and Dams on the Mississippi River System and Delta: This research article about the Mississippi River describes the changes that have been made to it over the years