Environmental Inventory and Assessment of Navigation Pools 24, 25, and 26, Upper Mississippi and Lower Illinois Rivers: A Vegetational Study.
MISSOURI BOTANICAL GARDEN ST LOUIS
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The purpose of the study was to provide a vegetation map and descriptions of vegetational types and their successional patterns to be used in an environmental impact analysis of the effects of maintenance and operation of the nine-foot navigation channel in Pools 24, 25, and 26 on the Upper Mississippi and Lower Illinois Rivers. Seven vegetation types were described after field examination of 116 stands Two nonforest types, old fields and wetlands and five forest types, willow, silver maple-cottonwood, silver maple-cottonwood-pin oak, pin oak, and oak-hickory. All of these types were mapped with the exception of old fields, which were omitted because they are often subject to cultivation after a short period of abandonment. The silver maple-cottonwood community was found to be the most extensive type. Analysis of successional trends indicated that ash Fraxinus spp. and American elm Ulmus americana may become more important in many of the silver maple forests and that pin oak forests may also replace them particularly in areas protected from flooding by levees.