|Title||Major shrubs of deciduous hardwood swamps in southeastern Michigan and their microsites|
|Year of Publication||1983|
|Academic Department||School of Natural Resources and Environment|
|Degree||Master of Science|
|Number of Pages||68 pp.|
|University||University of Michigan|
|City||Ann Arbor, MI|
The purpose of this study was to characterize the hardwood swamp communities of southeastern Michigan and examine the wetland shrubs and their microsites. In order to accomplish this goal several steps were taken: 1) soils were sampled and described, 2) the occurrence of shrub vegetation in six swamps was determined, 3) the microsites for shrubs were analyzed, 4) soil pH variability was examined, and 5) the other vegetation of these sites described. Field methods utilized transects and plot sampling to gather vegetation data. Measurement of soil pH was conducted in the field. Laboratory analyses employed analysis of variance and the Wilcoxon paired ranked-sign test. The specific objectives were: 1. To measure gradients in soil pH in mounds. 2. To describe the vegetation of six selected hardwood swamps. 3. To determine the occurrence and coverage of shrub species on mounds, flats and rises in two swamps. 4. To determine the occurrence and importance of tree species on mounds, flats and rises in two swamps. 5. To determine the occurrence and importance of herb species on mounds and flats in two swamps. 6. To study and describe aspects of the autecology of the following characteristic swamp species: Ilex verticillata, Vaccinium corymbosum, Cornus stolonifera, Lindera benzoin, Sambucus canadensis, and Toxicodendron vernix. Four major conclusions were reached: 1. Hardwood swamps of southeastern Michigan are characterized by specific wetland shrubs. ... 2. In mounds, the pH changed from the flat at the base of the mound where it is circumneutral or slightly acidic to the upper portions of the mound which were much more acidic. The pH values in the flat were 6.5 at North Lake and 4.5 at Cedar Lake, whereas the pH was 5.7 (North Lake) and 4.2 (Cedar Lake) on the upper portions of the mounds. 3. Dominant trees of hardwood swamps are Acer rubrum, Fraxinus nigra, and Betula alleghaniensis. Ulmus americana is present in the understory more than in the overstory and was a dominant prior to the Dutch elm disease. These trees also occur in different microsite habitats. 4. Herb species differ between mounds and flats by coverage of species rather than by the species present. For example, the primary coverage on mounds was from Carex lacustris and Urtica dioica. These same species were also present in flats but had greater percentage cover than on mounds.