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Phytosociology of the Lowland Forests of Northern Wisconsin
E. M. Christensen, J. J. (Jones) Clausen and J. T. Curtis
The American Midland Naturalist
Vol. 62, No. 1 (Jul., 1959), pp. 232-247
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2422555
Page Count: 16
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This paper presents a discussion of the lowland forests of northern Wisconsin based on phytosociological data from 108 stands. The substrates of these forests are subject to temporary or permanent high moisture content and are high in organic matter, often in the form of peat. Frequency, density, and dominance were recorded for the trees in each stand: frequency was determined for understory plants. The relative frequency, density, and dominance of tree species were added, resulting in an importance value. This importance value was weighted by an adaptation value for the tree species. The sum of the weighted importance values for any stand was the compositional index number for this stand, and stands were arranged along a gradient in order of increasing index numbers. The behavior of individual species was then graphed according to this gradient. Species were found to be arranged along this gradient in continuous sequence with no distinct groupings. The most important trees were Larix laricina and Picea mariana in the wettest, most acid sites, Thuja occidentalis, Abies balsamea and Fraxinus nigra on intermediate sites, and Tsuga canadensis, Betula lutea and Acer saccharum on the most nearly mesic, circumneutral sites. The characteristics of each of these three groupings are described in detail.
The American Midland Naturalist © 1959 The University of Notre Dame