THE LASTING EFFECTS OF THE GREAT MIDWEST FLOOD OF 1993 ON THE FLOODPLAIN 
FOREST OF THE UPPER MISSISSIPPI RIVER.
Yao Yin1, Robert Cosgriff2, Dawn Henderson3, and Joe Lundh4
1US Geological Survey, Upper Midwest Environmental Science Center, La Crosse, 
WI 54603.  2Illinois Natural History Survey, Great River Field Station, 
Brighton, IL 62012. 3Missouri Department of Conservation, Open Rivers 
Wetlands Field Station, Jackson, MO 63755.  4US Army Corps of Engineers, 
Mississippi River Project Rock Island District, Pleasant Valley, IA  52767.

A survey conducted in 1995 revealed massive tree mortality in the aftermath 
of The Great Midwest Flood of 1993.  Some of the 1995 survey plots were 
resurveyed in 2006.  The data reveal continued massive tree mortality after 
1995 in Pools 17, but not in Pool 26 and the Open River.  Light-seeded 
species, such as silver maple, eastern cottonwood, and black willow, and 
green ash regenerated abundantly.  Oak and hickory seedlings remained rare in 
the understory.   As of 2006, the density of samplings (2-10 cm in diameter) 
greatly exceeded the sapling density before the flood.  However, the density 
of trees (>= 10 diameter) recovered to pre-flood level only in the Open River 
but not in Pools 17 and 26.  On the basis of relative stem density among the 
species before and after the flood, the flood provided a competitive 
advantage to green ash in Pool 26, and to cottonwood and black willow in the 
Open River.

Keywords: flood, tree mortality, Mississippi River