Freshwater macrophyte communities in lakes of variable landscape position and development in northern Wisconsin, U.S.A.

Abstract

Using multivariate analyses, we evaluated the roles of landscape position and human development in the presence, composition, and abundance of freshwater macrophyte communities among 60 study lakes located in Vilas County, Wisconsin. These lakes varied in their position in a drainage network and surrounding land use as well as size, maximum depth, chemistry, and clarity. We used non-metric multidimensional scaling ordination, cluster analyses, and classification tree analyses to assess the multivariate relationships among macrophyte communities and environmental variables including an index of human development. Macrophyte communities in lakes high in the landscape were found to be dominated by isoetids while lakes low in the drainage network were dominated by elodeids due to the difference in bicarbonate concentrations. The presence of the human-introduced crayfish, Orconectes rusticus, had a high and significant correlation with the absence of macrophytes. An increase in human development correlated with a decrease in macrophyte abundance.