2023 Fiscal Year Final Research Report

Effects of soil organic matter dynamics on carbon dioxide emissions from forest subsoils

Research Project

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Project/Area Number	22K21335
Research Category	Grant-in-Aid for Research Activity Start-up
Allocation Type	Multi-year Fund
Review Section	1101:Environmental analyses and evaluation, environmental conservation measure and related fields
Research Institution	Japan Atomic Energy Agency
Principal Investigator	Abe Yukiko 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門原子力科学研究所原子力基礎工学研究センター, 博士研究員 (50966041)
Project Period (FY)	2022-08-31 – 2024-03-31
Keywords	下層土壌 / 火山灰土壌 / 土壌有機物 / 微生物呼吸 / 放射性炭素 / プライミング効果
Outline of Final Research Achievements	Forest soils are a large carbon reservoir and carbon release source. Therefore, elucidation of the carbon release process is essential for predicting future climate change. Especially, carbon dynamics in subsoil remains largely unknown. The aim of this study was to determine the contribution of the subsoil to the amount of carbon dioxide (CO2) emitted from soil and the decomposition process of soil organic matter (SOM) in the subsoil for forest soils with different parent materials. The results showed that regardless of soil type, a nonnegligible amount of CO2 was found to be emitted from the forest subsoil. In addition, radiocarbon analysis showed that the majority of the CO2 emitted from the subsoil was from the decomposition of SOM fixed since 1960s.
Free Research Field	土壌炭素循環
Academic Significance and Societal Importance of the Research Achievements	気候変動に伴う炭素収支を評価するために、土壌の炭素動態を正確に評価することが求められている。これまで実施された土壌炭素循環研究の多くは、表層土壌を対象としているが、森林土壌に蓄積されている炭素のおよそ半分は下層土壌に蓄積されている。本研究の成果は、気候変動下での土壌炭素動態を予測する際に下層土壌を考慮する必要があることを示しており、土壌炭素動態のメカニズムの解明やモデルの精緻化に繋がるものである。