Conditions for the establishment of tropical dry evergreen forests with extremely high tree heights from the perspective of soil moisture supply capacity

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K06153
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40010:Forest science-related
• Research Institution: Forest Research and Management Organization
• Principal Investigator: OHNUKI Yasuhiro 国立研究開発法人森林研究・整備機構, 森林総合研究所, 研究専門員 (10353616)
• Co-Investigator(Kenkyū-buntansha): 鳥山 淳平 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 (00582743)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 土壌水分 / 深層土壌 / 乾燥常緑林 / 乾燥落葉林 / 根系到達深度 / 土壌特性 / 樹高

Outline of Final Research Achievements

In order to clarify the soil moisture supply capacity that supports transpiration during the dry season in dry evergreen forests distributed in tropical monsoon regions, a simulation was performed using a numerical model and verified with actual measurements. As a result, when the numerical model was used to analyze the extremely dry period of 2015-2016, it was confirmed that the reproducibility of soil moisture was reasonably high if the root depth was assumed to be 8m and the level of decrease in evapotranspiration rate was set. In the field demonstration study, it was confirmed that the groundwater level fluctuation in response to rainfall was significantly different between evergreen forests and sparse forests, that the soil layer in evergreen forests was thicker and the surface soil moisture content was higher than in sparse forests and deciduous forests, and that these may affect the tree height distribution of those forests.

Free Research Field

森林土壌学

Academic Significance and Societal Importance of the Research Achievements

平地乾燥常緑林の成立条件を解明するために、植生タイプごとの土壌水分供給能の違いを実測値の比較により明らかにし、数値モデルによる土壌水分移動シミュレーションにより、スーパーエルニーニョの特異年における土壌水分動態を再現できた。これにより、気候変動の影響を受けやすい熱帯モンスーン地域における、森林の劣化、減少、回復等の様々なシナリオを想定した、水資源の動態予測に貢献できる。