The main objective of the Corps' tree planting program on the Mississippi River is to restore the hard-mast species (Oak and Hickory species) to the Rivers' forest ecosystem. The hard-mast species of Bur Oak, Swamp White Oak, Pin Oak, Northern Pecan, Shellbark Hickory, and to a limited extent Walnut and Northern Red Oak was once a more prevalent forest component than it is today. Reasons for the decline in the hard-mast component include vast over-cutting in the 1800's for agriculture and steamboat use, increased water tables from the Nine-foot Navigation Project, and highgrading from past management programs.
After many years of planting trees in the bottomlands, the forest management program has focused on planting larger stock trees to enhance survivability. The annual flood pulse of the River often will kill up to seventy-five percent or more of seedling plantings, and a much higher percentage in direct seed plantings. Larger floods will kill even higher percentages of these categories. Also, weed competition will overtop and block sunlight and rob nutrients from all but the large stock plantings. Mowing and herbicide can be applied to seed and seedling plantings, but equipment access on the River is often limited, or nearly non-existent. With large stock plantings one can plant the trees and "walk away" from them with assurance of good survivability. Since the program is geared at restoring a hard mast "component", fewer trees can be planted per acre than seed and seedling plantings with the same projected survival results. Cost is comparable too. The large stock trees initially cost more money, but there is no costly follow-up maintenance. Many former agricultural leases have been converted to trees with a hard-mast component. Some of the forest management patch cut areas have also been planted with mast producing trees.
The 1993 Flood significantly impacted much of the forest resource, but also increased opportunites for restoring the hard-mast resource that is in decline on the river. Hackberry is an indicator species for where hard-mast trees can grow. The 1993 flood killed up to 100% of the hackberry in some of the pools south of the Quad Cities. In areas where these hackberry used to exist, we can plant hard-mast species with confidence that the area is high enough in elevation. Where hackberry existed in solid stands, there is now an open canopy for sunlight to reach the forest floor. Querying our GIS database gets us locations of these potential hard-mast planting sites. We have been planting trees in these sites with sucess since 1996. Another program that has also benefited the hard mast tree resource of the Mississippi River is the Section 1135 Program of the 1986 Water Resources Development Act as amended. This program calls for cost sharing by a non-federal sponsor and has been successful in planting many areas to mast producing trees. Several of the sponsors have been Trees Forever, and American Forests.