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The Long-Term Influence of Levees on the Forested Floodplain Communities of the Wisconsin RiverEPA Grant Number: U915404
Title: The Long-Term Influence of Levees on the Forested Floodplain Communities of the Wisconsin River
Investigators: Gergel, Sarah E.
Institution: University of Wisconsin - Extension
EPA Project Officer: Broadway, Virginia
Project Period: September 1, 1998 through September 1, 2001
Project Amount: $49,626
RFA: STAR Graduate Fellowships (1998) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems
The objective of this research project is to determine whether the diversity and relative abundance of tree species and the density of invasive shrubs differ between unleveed areas of the Wisconsin River floodplain and areas that have been leveed for approximately 100 years.
Ten transects (0.5 to 1.5 km in length), each with 10 randomly spaced 10-m x 20-m plots, were established perpendicular to the river's edge in undisturbed floodplain forest. One hundred plots were distributed in areas inside levees, areas outside (or behind) levees, and in unleveed areas. Trees greater than 2.5 cm dbh (diameter at breast height) in each plot were measured and identified to species. The density of invasive shrubs, Honeysuckle (Lonicera spp.), Buckthorn (Rhamnus spp.), and Prickly Ash (Zanthoxylem americanum) was measured in two belt transects in each plot. The location and elevation of each plot was determined using a global positioning system in the field and a digital terrain model with 2-ft contour intervals. The flood frequency of each plot was estimated using the HEC-2 program. Analysis of covariance was used to determine differences in tree community structure and composition between leveed and unleveed sites, while accounting for the effects of distance and elevation. Community structure and composition were measured as relative density, relative abundance, and importance values. Density and presence/absence of invasive shrubs were used as dependent variables in logistic regression. Canonical Correspondence Analysis was used to relate vegetation composition to ridge and swale topography, distance to the river, flood frequencies, and elevation.