Forest growth and species diversity due to global warming in mountainous areas using nitrogen isotope analysis

2019 Fiscal Year Final Research Report

• Project/Area Number: 19K21157
• Project/Area Number (Other): 18H06017 (2018)
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund (2019); Single-year Grants (2018)
• Review Section: 0603:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: Shinshu University
• Principal Investigator: ODA Ayumi (小田あゆみ) 信州大学, 学術研究院農学系, 助手 (40571609)
• Project Period (FY): 2018-08-24 – 2020-03-31
• Keywords: 窒素同位体比 / 山岳地域 / 気候変動 / 硝酸態窒素

Outline of Final Research Achievements

In this study, we analyzed the inorganic nitrogen content in the soil and the nitrogen source and growth rate of tree species at three forest stands with different altitudes in mountain area. In the highest altitude plot of this study indicated higher ammonium content in the soil which produce the early stage of the decomposition process. While in the lower altitude plots, nitrate which is a nitrogen form that has undergone decomposition was higher than higher altitude plots. Growth rate of trees were larger in the lower altitude plots and the number of tree species using nitrate also increased in lower altitude plots. As a results, global warming promote the decomposition of nitrogen will proceed and the growth of forests will increase, but on the other hand, competition between species may change, such as the decrease in tree species that cannot cope with changes in nitrogen sources.

Free Research Field

森林生態学

Academic Significance and Societal Importance of the Research Achievements

本研究の意義は、温暖化の影響を受けやすいと考えられながらも、これまで調査が行われていなかった山岳地域の森林生態系において、土壌中の養分状態の変化が森林の成長量とどのような関係があるかを明らかにした点である。これにより、高標高地域では土壌中に有機物の蓄積があるものの分解が進まないこと、温暖化により分解が促進されると、従来存在していた窒素形態が変化し、その変化に順応できない樹種が存在する可能性を示した。このような養分吸収における樹種特性を理解することは、温暖化による森林生態系の変化を予測するために重要である。