The development and ecology of peatlands in Indiana
Abstract
The objectives of the present study were to (1) summarize the natural and human history of Indiana's peatlands, (2) compare peatland frequency and distribution to surface physiography, (3) investigate effects of basin morphometry on peatland formation, (4) reconstruct the development of Indiana's peatlands using subfossils, and (5) characterize the vegetation of Indiana's peatlands along environmental and temporal gradients. Historic accounts of nearly 100 peatlands indicate that the previous abundance of bogs and fens in Indiana had a significant effect on agriculture and industry. Characteristic soils show over 62,000 ha of peatland in Indiana. The highest concentrations are within the former boundaries of the stagnant Saginaw Lobe of Wisconsin glaciation (ca. 15,000 yrs. BP). Within this area, peatlands were significantly more frequent in mixed drift resulting from collapse of sub-ice tunnels and open ice-walled channels. Peatlands were significantly less frequent in morainal topography and loam till of Trafalfgar formation, sand and gravel deposits in outwash fans, and ice-contact sand and gravel ridges. The most significant morphometric qualities of individual basins favoring peat formation were small surface area and protection from wave erosion. The mean surface area of non-peat-forming basins was significantly larger. Maximum, mean, and relative depth, volume, and shoreline development were variable among peatland basins. Acid-forming, Sphagnum-dominated peatlands had smaller watersheds and deeper clay and silt hardpans than strongly minerotrophic fens. Coring and macrofossil analysis of ten non-riparian peatlands showed that all began as mesotrophic or eutrophic lakes, developed into marshes characterized by emergent vegetation (Nuphar, Nymphaea, and Brasenia), and the moss Drepanocladus aduncus (submergent form). Ninety percent of the basins developed a fen mat characterized by the mosses Calliergon trifarium and Meesia triquetra. While some basins became forested immediately after the fen stage, many became Sphagnum-dominated leatherleaf bogs and produced up to 4.5 m of Sphagnum peat. The flora of leatherleaf bogs exhibits a mixed geographic affinity characteristic to the southern Great Lakes region. Peatland plant assemblages in southern Michigan and Indiana are different from those in northern Michigan, Ohio, and the northeast. Regardless of their trophic origins, all Indiana peatlands senesce into lowland forests dominated by Acer rubrum.
Degree
Ph.D.
Advisors
Parker, Purdue University.
Subject Area
Botany|Ecology|Freshwater ecology
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