| Project/Area Number |
14340241
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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 Tohoku University, Graduate School of Life Sciences, Professor, 大学院・生命科学研究科, 教授 (90092311)
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| Co-Investigator(Kenkyū-buntansha) |
HIKOSAKA Kouki Tohoku University, Graduate School of Life Sciences, Associate Professor, 大学院・生命科学研究科, 助教授 (10272006)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥14,600,000 (Direct Cost: ¥14,600,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2003: ¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 2002: ¥8,500,000 (Direct Cost: ¥8,500,000)
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| Keywords | Leaf phenology / Canopy photosynthesis models / Lifespan / Stratification / Nitrogen use efficiency / Forest / Nitrogen productivity / Mean residence time |
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| Research Abstract |
The lifespan of leaves is shorter than that of individuals, and plants produce and shed their leaves in the growth period. The pattern of leaf production and shedding is different among species as is represented in evergreen and deciduous species. We considered difference in leaf phenology as a strategy of plants to adapt themselves to changing environments. Applying a canopy photosynthesis model to the analysis of leaf phenology, we developed a new model of leaf dynamics and nitrogen. The model predicted optimal LAI, canopy photosynthesis, leaf lifespan, nitrogen use efficiency, and also their responses to changes in nitrogen and light availability. In experimentally established herbaceous stands, we analysed the factors responsible for leaf production and shedding. Leaf area loss rate increased in shaded leaves with an increase in N retranslocation to meet the N demand for growth of the plant. We demonstrated that leaves were discarded Oven though maintaining those leaves longer would contribute to plant growth at low N availability, while at high N availability leaves were not discarded even though retranslocation of N associated with leaf loss would increase total plant growth rate. In a beech forest, we found that canopy and understorey tree species had a similar N resorption rate that did not depend on the light availability. In the same forest, we found that leaf level N use efficiency was not significantly different between canopy and understorey species, though the mechanism was very different from each other. Canopy species had a high N productivity with a low mean residence time of N, while understorey species had a high residence time of N with a low N productivity. We studied responses of leaf photosynthesis to environmental changes. Availability of vacant space in mesophyll cell surfaces to accomodate enlarged chloroplasts is indispensable to positively respond to sudden increase in light climate.
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