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Soil Science Society of America Journal Abstract - PEDOLOGY

Landscape Determinants of Exchangeable Calcium and Magnesium in Ozark Highland Forest Soils


This article in SSSAJ

  1. Vol. 75 No. 1, p. 164-180
    Received: Oct 5, 2009

    * Corresponding author(s): jkabrick@fs.fed.us
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  1. John M. Kabrick *abcde,
  2. Keith W. Goyneb,
  3. Zhaofei Fanc and
  4. Dennis Meinertd
  1. a Missouri Dep. of Natural Resources P.O. Box 176 Jefferson City, MO 65102
    b USDA Forest Service Northern Research Station 202 Natural Resources Bldg. Univ. of Missouri Columbia, MO 65211
    c Dep. of Soil, Environmental and Atmospheric Sciences 302 Natural Resources Bldg. Univ. of Missouri Columbia, MO 65211
    d Dep. of Forestry 327 Thompson Hall Mississippi State Univ. Mississippi State, MS 39762
    e Missouri Dep. of Natural Resources P.O. Box 176 Jefferson City, MO 65102


Exchangeable base cations, particularly Ca and Mg, largely govern soil acidity and, consequently, plant species composition in temperate forests. Although studies have identified soil and terrain characteristics affecting exchangeable Ca and Mg, few studies have identified the relative importance of factors affecting Ca and Mg distribution across landscapes. Objectives of this study were to: (i) identify the relative importance of geomorphic and soil properties for exchangeable Ca and Mg concentrations and quantities, and (ii) examine relationships between these properties and tree species abundance. A classification and regression tree (CART) analysis was applied to 74 pedons sampled across a 3800-ha forested research area in the Ozark Highlands in southeastern Missouri. This analysis identified depth to bedrock and the bedrock lithology as important factors associated with exchangeable Ca and Mg concentrations, which ranged from 0.30 to 2.88 and 0.24 to 1.35 g kg−1, respectively. The CART analysis also indicated that the underlying bedrock was associated with exchangeable base cation quantity, and values ranged from 4263 to 20,144 kg ha−1 for Ca and 1650 to 9977 kg ha−1 for Mg. Analysis of variance indicated that the most common oak (Quercus L.) and hickory (Carya Nutt.) species were significantly more abundant on soils with lower Ca concentrations. The analysis framework applied in this study provides a basis for distinguishing among soils and ecological land types by pools of exchangeable Ca and Mg, thereby aiding in the identification of locales where base cation depletion may be of concern.

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