Construction of an Oxygen and Hydrogen Isotope Ratio Model of Tree Pith for High Time-Resolution Reconstruction of Precipitation History

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19854
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 63:Environmental analyses and evaluation and related fields
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Kagawa Akira 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (40353635)
• Co-Investigator(Kenkyū-buntansha): 久保田 多余子 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (70353670)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 酸素同位体比 / 炭素同位体比 / 水素同位体比 / 日輪

Outline of Final Research Achievements

In this study, the objectives were: 1) to measure the isotope ratios in the pith of seedlings, and 2) to construct a model explaining the isotope ratios in the pith and verify the accuracy with which precipitation can be reconstructed. The initially predicted peaks in the oxygen isotope ratio, which were expected to reflect precipitation events, were only observed at approximately 7 cm from the apex. They were not clearly observed in the parts below this, indicating that reconstruction from oxygen isotope ratios is difficult.

Free Research Field

安定同位体年輪年代学

Academic Significance and Societal Importance of the Research Achievements

髄の炭素同位体比分析により、日～週単位という高時間分解能での過去の天気を復元する可能性があることを示せたという点では、学術的意義および社会的意義は高いと思われるが、実際に過去の天候（晴天・曇天・雨天）を日～週単位という高時間分解能で復元するまでには、複数の個体で炭素同位体比の変動が同調することを確認し、髄の形成時期を正確に推定できるようになることが必要であり、さらなる研究の継続が必要である。