| Project/Area Number |
09041142
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生態
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
HIROSE Tadaki Graduate School of Science, Tohoku University, Professor, 大学院・理学研究科, 教授 (90092311)
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| Co-Investigator(Kenkyū-buntansha) |
HIKOSAKA Kouki Graduate School of Science, Tohoku University, Associate Prof., 大学院・理学研究科, 助教授 (10272006)
NIINEMETS Ul エストニア生態学研究所, 上級研究員
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥6,400,000 (Direct Cost: ¥6,400,000)
Fiscal Year 1999: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1998: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Nitrogen use efficiency / Water use efficiency / C4 / climate / grazing / grassland / Canopy structure / Mongolia / 草原群集 / 群落生産 / 多様性 / 炭素安定同位体 / 炭素安定同位体比 |
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| Research Abstract |
We studied the nitrogen use efficiency (NUE) and water use efficiency (WUE) of species growing in a humidity gradient in Mongolian grasslands to examine if there is a trade-off between the two efficiencies. Total 131 species were collected from 7 sites. WUE was evaluated by the compositional deviation of ィイD113ィエD1C(δィイD113ィエD1C). NUE was evaluated as a reciprocal of leaf nitrogen concentration (LNC). Species in drier habitats tended to have higher WUE, but there was no such trend in NUE. No trade-off was found between WUE and NUE across species distributed in different climates. However, when the values for WUE and NUE were standardized against their means for species found more than three sites, WUE increased and NUE decreased with increasing aridity, indicating the trade-off between NUE and WUE within species. Only two (Cleistogenes squarrosa and Salsola passerina) out of 131 species were found to have the C4 metabolism.
Effects of climate and grazing intensities on the structure of grassland vegetation were studied. We have established three exclosures in different climates : Partizan (mesic steppe), Tumentsogt (typical steppe) and Bayan-Unjuul (dry steppe). First year vegetation survey gave 45 species (including 7 grasses) in Partizan, 46 species (8 grasses) in Tumentsogt and 18 species (4 grasses) in Bayan-Unjuul. Aboveground biomass was 122 g dw mィイD2-2ィエD2 at Parizan, 122 at Tumentsogt, and 53 at Bayan-Unjuul. Difference between exclosure and grazing plots was small, probably because of the short time since establishment of the exclosure and an unusually dry summer in 1999.
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