Identification of Annual Flood Durations Associated with Tree Species in the Upper Mississippi River System Floodplain, with Applications to Forest Restoration

Abstract

The Upper Mississippi River System (UMRS) is a highly altered river complex in the Midwestern United States that has been managed to provide a unique balance of economic, recreational, and environmental benefits to society. Manipulation of the river’s flows to support this multipurpose system has resulted in dramatic changes to the structure and function of various aquatic and terrestrial habitats, including floodplain forests. There is increased interest in restoring floodplain forests in the UMRS; however, the silvics of individual species and dynamics of floodplain forest stands are only marginally understood. The purpose of this study was to i) identify growing season flood durations that are suitable for individual tree species in the UMRS and (ii) demonstrate how those results can be applied at the project scale for use in forest restoration and management. The 10th, 50th, and 90th percentile values of average annual growing season flood duration were identified for 17 UMRS tree species by integrating a spatially explicit forest inventory dataset from Mississippi River pools 3-10 with plot level elevation data and estimates of average annual growing season flood duration for the nearest river mile. This range was used to describe the ecological amplitude of each species related to hydrologic conditions, with annual days of inundation providing a measure of hydrologic variability. The results of this study demonstrate the varying flood tolerance of UMRS floodplain forest trees at the species level and can be used by river managers to aid in the development of planting plans and the design of habitat restoration and enhancement efforts.