Is tree having thick and dense crown vulnerable for global warming? Validation of a new hypothesis for inter-species variations in crown structure

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K19141
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: Shizuoka University
• Principal Investigator: Iio Atsuhiro 静岡大学, 農学部, 准教授 (90422740)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 光合成 / 温度応答 / 葉分布構造 / 遷移前期種 / 遷移後期種

Outline of Final Research Achievements

To test the hypothesis that late-successional trees are more vulnerable to warming than early-successional trees, we compared the temperature response curve of leaf photosynthesis and the three-dimensional distribution of leaf area between early-successional and late-successional species. Both photosynthetic capacity and optimum temperature showed higher values for early-successional species than for late-successional species, regardless of growth light environment of leaves. Early-successional species concentrated their leaves in the upper part of canopy, resulting in a lower proportion of shade leaves than late-successional species. However, contrary to my expectation, the optimal temperature of photosynthesis in late-successional species increased with decreasing growth irradiance. This unexpected result was attributed to the very low respiration rate of shade leaves in late-successional species. Therefore, the initial hypothesis was rejected.

Free Research Field

森林生理生態

Academic Significance and Societal Importance of the Research Achievements

樹木の光合成の温度応答を、葉の生理機能だけでなく個体の葉分布構造も含めて解析し、代表的な遷移後期種であるブナについて、内部が暗く陰葉が多いにも関わらず、呼吸速度を低く抑えることで光合成最適温度を高く維持していることを示した。葉の多い遷移後期種がどのように高温に対応するのかを示した重要な知見であり、温度化にともなう森林生産量および樹木動態の変化予測の精緻化への貢献が期待される。