Clarification of generality of temperature independent diurnal fluctuation of root respiration.

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K11624
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Tsuru University
• Principal Investigator: Bekku Yukiko (別宮有紀子) 都留文科大学, 教養学部, 教授 (20326094)
• Co-Investigator(Kenkyū-buntansha): 坂田 剛 北里大学, 一般教育部, 准教授 (60205747)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 陸上生態系 / 炭素循環 / 根の呼吸 / 蒸散速度

Outline of Final Research Achievements

Root respiration is an essential factor in estimating the carbon balance of terrestrial ecosystems. Since root respiration affects the estimation of heterotrophic respiration (= decomposition of soil organic matter), the carbon-balance estimation varies greatly depending on the root respiration value.
We measured root respiration and leaf transpiration, photosynthesis, and water flow in xylem vessel at the trunk of subtropical trees (Hibiscus glaber, Rhaphiolepis umbellate) in Ogasawara islands using optical dissolved O2 sensor (VisiFerm), portable photosynthesis measurement system (Li-6400), and sap flow meter (SFM1). Root respiration rates of both species changed significantly independent with root temperature in midday, and it seems to be related with leaf transpiration rates. Our results indicate that root respiration would be affected by water use of plants. This means that the carbon balance in terrestrial ecosystems links possibly with the water use of plants.

Free Research Field

生態系生態学

Academic Significance and Societal Importance of the Research Achievements

根の呼吸速度は、陸上生態系の炭素循環量を推定する上で非常に重要な要素である。本研究では、亜熱帯と暖温帯性の樹種3種の根の呼吸速度が、葉の蒸散速度の影響を受けて、日中に大きく変動することが明らかになった。これは、陸上生態系の炭素循環量を高精度に推定する上で、根の呼吸が葉の蒸散速度に影響を受けるというプロセスを考慮する必要があることを示している。今後は更なる一般化・モデル化のための研究をおこないたい。