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Soil Science Society of America Journal Abstract - DIVISION S-7—FOREST & RANGE SOILS

Changes in Microbial Nitrogen Across a 100-Year Chronosequence of Upland Hardwood Forests


This article in SSSAJ

  1. Vol. 66 No. 5, p. 1662-1668
    Received: Jan 26, 2001

    * Corresponding author(s): twidol@ucdavis.edu
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  1. Travis W. Idol *a,
  2. Phillip E. Popeb and
  3. Felix Ponderc
  1. a Dep. of Land, Air, and Water Resources, Univ. of California-Davis, One Shields Ave, Davis, CA 95616
    b Dep. of Forestry and Natural Resources, Purdue Univ., 1159 Forestry Bldg, West Lafayette, IN 47907
    c USDA-Forest Service, North Central Research Station, 208 Foster Hall, Chestnut St., Lincoln Univ., Jefferson University, MO 65102


Soil microorganisms mediate many of the major processes involved in soil N cycling. Also, they are strong competitors with plants for available soil N. Thus, changes in microbial N because of forest harvesting may have significant impacts on N availability and overall forest N cycling. A chronosequence of upland hardwood forest stands in southern Indiana, USA, ranging in age from 1 to 100 yr since last harvest, was chosen to evaluate changes in microbial N with stand development. Microbial N was measured in the A and B soil horizons during different seasons from 1997 to 1999. Peak levels of microbial N were highest in the youngest forest stand (1 to 3 yr old), but seasonal variability was greater than differences by stand age. Microbial N concentration (mg kg−1) varied significantly by season and soil horizon within stands ranging in age from 1 to 30 yr since harvest, but not in the mature, 80- to 100-yr-old stand. There were few significant differences in microbial N content (kg ha−1). Harvesting did not appear to have long-term effects on microbial N, but spatial variability in microbial N appeared to be greater in the younger forest stands.

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Copyright © 2002. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.66:1662–1668.