Natural 15N 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


72 被引用数 (Scopus)


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 NO 3- pool at this site, we concluded that plant δ 15N 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.

出版ステータスPublished - 8月 2003

ASJC Scopus subject areas

  • 生態、進化、行動および分類学
  • 環境化学
  • 生態学


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