Changes in Microbial Nitrogen Across a 100-Year Chronosequence of Upland Hardwood Forests
- Travis W. Idol *a,
- Phillip E. Popeb and
- Felix Ponderc
- 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2002.