2021 Fiscal Year Final Research Report
How devastated coniferous plantations negatively affect the environment and how this problem can be remedied?
| Project/Area Number |
19H03088
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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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| Review Section |
Basic Section 41050:Environmental agriculture-related
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| Research Institution | Kyushu University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 人工林 / 雨水配分 / 樹幹流 / 樹冠通過雨 / 環境 |
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| Outline of Final Research Achievements |
This study investigated the environmental influence of unmanaged coniferous plantations and the way of coping with it mainly in the context of rainfall partitioning (RP) into throughfall (TF), stemflow (SF), and interception loss (IL). The results showed that 1) stand density (SD) was the dominant index of stand structure influencing RP, 2) TF ratio almost linearly decreased with increasing SD, 3) SF and IL ratios increased with increasing SD up to about 2500 trees/ha, but in the range more than that, 4) SF ratio increased at a higher rate, but 5) IL ratio took a downward turn, 6) TF ratio was influenced by the situation of dead branches, and 7) stand SF funneling ratio decreased with increasing diameter at breast height (DBH), which implied that forest management such as thinning should control RP of coniferous plantations.
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| Free Research Field |
森林水文学
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| Academic Significance and Societal Importance of the Research Achievements |
近年，豪雨の増加に伴って大規模森林災害が多発し，災害に強い森づくりの重要性が高まっている．森林では，過密になるほど遮断損失が増加し，林内雨（樹冠通過雨と樹幹流の和）が減少するため，豪雨を軽減する効果がある．しかし，樹幹流率が増加して局所的な雨水集中が増加し，樹冠通過雨率は減少するものの，滴下雨成分が増加するため林床により強い雨滴衝撃を与える可能性が高い．本研究は，針葉樹人工林の林分構造と雨水配分の関係を観測し，管理放棄された荒廃人工林とその管理が雨水配分にどのような影響を及ぼすかを明らかにし，枝打ち・間伐等の保育作業によって山地災害軽減の可能性があることを示唆した点で学術的・社会的意義がある．
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