Date of Award
Master of Science
Many plant and animal species rely on tallgrass prairie and sand savanna ecosystems that once covered much of northern to central Illinois but are now fragmented landscapes across the Midwest. In northeastern Illinois, The Nature Conservancy manages five sites containing fragments of remaining tallgrass prairie and sand savanna within the Kankakee Sands section of Illinois using techniques such as prescribed burning and invasive species removal. The objective of this study was to conduct an eighteen-year resampling of the ground flora to assess management impacts on species composition and conservation status. Permanent transect lines were resampled using a 1m² quadrat to determine the Cover Class (%) of each species <50 cm in height that were rooted inside the quadrat. Species composition was characterized by three values: Shannon-Wiener Diversity Index (H’), the Floristic Quality Index (FQI), and the mean Coefficient of Conservatism (C̅). Linear regression was used to illustrate the relationship between fire occurrence and species composition on the landscape over 18 years of management. To test whether frequency of management had a significant effect on a site’s FQI, H’, C̅, a Kruskal-Wallis one-way nonparametric analysis of variance test was used. ANOVA was used to test for physiognomic changes in vegetation. Results concluded that while there were non-significant changes in the species composition of the sites, there were significant physiognomic changes in the Kankakee Sands sites between 2002-2020. These results suggest current management regimes are working to ii maintain the quality natural areas that make up the Kankakee Sands sites, however, increased coverage of Rhus species threatens to displace valued prairie and savanna species threatening the quality of these natural areas. Land managers of the Kankakee Sands and other such habitats should consider targeted management of Rhus copallinum and Rhus glabra with herbicides, as well as practice flexibility regarding the seasons in which they burn such sites.
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