JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. The University of Notre Dame is collaborating with JSTOR to digitize, preserve and extend access to American Midland Naturalist. ABSTRACT: The relationships

more »

... een plant species composition and dispersion, water chemistry and water depth/depth to water table were studied in five calcareous intradunal ponds (pannes) bordering the southern tip of Lake Michigan. The panne systems contained eight plant species threatened and endangered in Indiana. The aquatic zone was dominated by Chara, the pond edge by Rhynchospora capillacea, Juncus balticus and Utricularia cornuta, and the area surrounding the pond by Hypericum kalmianum. The water chemistry was typical of hardwater ponds in the area, probably affecting species composition but not species dispersion within the pannes. A significant correlation between the first axis scores from a reciprocal-averaging ordination and water depth/depth to water was demonstrated. Panne species are fitted to a model based on hydrology proposed by van der Laan for dune-slack vegetation in the Netherlands.