2002 Fiscal Year Final Research Report Summary
Energy and water cycles in Siberian biosphere
| Project/Area Number |
11201206
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
OHTA Takeshi Nagoya University, Graduate school of Bioagricultural Sciences, Professor, 大学院・生命農学研究科, 教授 (20152142)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUSHIMA Yoshihiro Research Institute for Humanity and Nature, Professor, 総合地球環境学研究所, 教授 (00026402)
HIYAMA Tetsuya HyARC Nagoya University, Associate Professor, 地球水環境研究センター, 助教授 (30283451)
NAKAWO Masayoshi Research Institute for Humanity and Nature, Professor, 総合地球環境学研究所, 教授 (90142695)
KUBOTA Jumpei Faculty of Agriculture, Tokyo University of Agriculture and Technology, Associate Professor, 農学部, 助教授 (90195503)
YOSHIKAWA Ken Faculty of Agriculture, Okayama University, Professor, 農学部, 教授 (50166922)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Siberia / Water and energy cycles / Different forest types / Permafrost / Climatic condition |
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| Research Abstract |
1. The sum of the turbulent fluxes was generally in good agreement with the available energy flux, except when the latent heat flux was large, when the total turbulent fluxes often exceeded the available energy flux ; this bias in the energy balance was affected by the wind direction. Although the reasons for this phenomenon at this site are not clear, it might be an effect of the larch forest surrounding the site.
2. The seasonal variation and magnitude of the latent heat flux (IE) were similar to those of the sensible heat flux (H) ; both were maximal in June, Consequently, the Bowen ratio was around 1.0 on many days during the study period. On some clear days just after rainfall events, IE was very large, and the sum of H and IE exceeded the net all-wave radiation.
3. Remarkably, from 7 to 22 July 2000, which corresponded to a long rainless period, IE decreased and was smaller than H. Considering the diurnal change in the saturation deficit and soil moisture for the same period, it is thought that IE was affected by the atmosphere rather than by the soil.
4. The contribution of understory evapotranspiration (Eu) to the evapotranspiration from the entire ecosystem (Et) was 25-50% of Et throughout the period analyzed, and a similar relationship was obtained for overstory transpiration (Eo). These results suggest that Eu plays a very important role in the water cycle at this site.
5. Significant differences in the water and energy exchanges of the pine and larch forests at Spasskaya Pad occurred just after the snowmelt season. This could have been due to the difference in species (evergreen versus deciduous forest) or in soil thawing conditions. Consequently, the shape of the seasonal variation in the Bowen ratio over the course of the study period at the pine site was markedly different from that in the larch forest.
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