Ecosystems

, Volume 6, Issue 5, pp 457–469

Natural15 N Abundance of Plants and Soil N in a Temperate Coniferous Forest

  • Keisuke Koba
  • Muneto Hirobe
  • Lina Koyama
  • Ayato Kohzu
  • Naoko Tokuchi
  • Knute John Nadelhoffer
  • Eitaro Wada
  • Hiroshi Takeda
Article

DOI: 10.1007/s10021-002-0132-6

Cite this article as:
Koba, K., Hirobe, M., Koyama, L. et al. Ecosystems (2003) 6: 457. doi:10.1007/s10021-002-0132-6
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Abstract

Measurement of nitrogen isotopic composition (δ15N) of plants and soil nitrogen might allow the characteristics of N transformation in an ecosystem to be detected. We tested the measurement of δ15N for its ability to provide a picture of N dynamics at the ecosystem level by doing a simple comparison of δ15N between soil N pools and plants, and by using an existing model. δ15N of plants and soil N was measured together with foliar nitrate reductase activity (NRA) and the foliar NO3 pool at two sites with different nitrification rates in a temperature forest in Japan. δ15N of plants was similar to that of soil NO3 in the high-nitrification site. Because of high foliar NRA and the large foliar NO3 pool at this site, we concluded that plant δ15N indicated a great reliance of plants on soil NO3 there. However, many δ15N of soil N overlapped each other at the other site, and δ15N could not provide definitive evidence of the N source. The existing model was verified by measured δ15N of soil inorganic N and it explained the variations of plant δ15N between the two sites in the context of relative importance of nitrification, but more information about isotopic fractionations during plant N uptake is required for quantitative discussions about the plant N source. The model applied here can provide a basis to compare δ15N signatures from different ecosystems and to understand N dynamics.

Keywords

nitrogen isotope rationitrogen availabilitynitrogen dynamicsnitrate reductase activityfoliar NO3modeling

Copyright information

© Springer-Verlag New York, Inc. 2003

Authors and Affiliations

  • Keisuke Koba
    • 1
    • 2
    • 3
  • Muneto Hirobe
    • 1
    • 4
  • Lina Koyama
    • 1
    • 5
  • Ayato Kohzu
    • 6
  • Naoko Tokuchi
    • 1
    • 7
  • Knute John Nadelhoffer
    • 3
    • 8
  • Eitaro Wada
    • 7
    • 9
  • Hiroshi Takeda
    • 1
  1. 1.Graduate School of AgricultureKyoto University, 606-8502 Kyoto CityJapan
  2. 2.Graduate School of InformaticsKyoto University, 606-8501 Kyoto CityJapan
  3. 3.The Ecosystems CenterMarine Biological Laboratory, 7 MBL Street, Woods Hole, Massachusetts 02543USA
  4. 4.Faculty of AgricultureMiyazaki University, Miyazaki 889-2192Japan
  5. 5.Graduate School of Natural Science and TechnologyKanazawa University, Ishikawa 920-1192Japan
  6. 6.Center for Ecological ResearchKyoto University, 520-0105 Ohtsu CityJapan
  7. 7.Field Science Education and Research CenterKyoto University, Kyoto 606-8502Japan
  8. 8.University of Michigan Biological Station, Ann Arbor, Michigan 48109-1090USA
  9. 9.Research Institute of Humanity and Nature, Kyoto 602-0878Japan