Vegetation Dynamics on the Floodplain of the Lower Chippewa River in Wisconsin

Abstract

BARNES, W. J. (Biology Department, University of Wisconsin-Eau Claire, WI 54702). Vegetation dynamics on the floodplain of the lower Chippewa River. Journal of the Torrey Botanical Society 124:189-197. 1997.Changes in the composition and species diversity of trees in the floodplain forests of the lower Chippewa River since the time of settlement (ca. 1850) were studied. General Land Office survey records were used to compare tree diameters and species composition of presettlement riverbank trees with those presently occurring. The developmental sequence of tree species in floodplain forests was examined using a series of islands of different ages. Eight dams have been constructed on the upper Chippewa River, and they have had an effect on seasonal flow and meandering in the lower reaches. The present riverbanks are more stable than prior to dam construction, and changes have occurred in the composition of their forests. Contemporary floodplain forests have larger trees than at the time of settlement in ca. 1850 and are less diverse. They are dominated by silver maple, which is three times as abundant as it was prior to settlement. Silver maple has replaced cottonwood and black willow as major colonizing species and presently occurs in all size classes in these forests.