Verification of forest evapotranspiration estimated by water budget using isotope dendrochronology

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K07796
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Forest science
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Kubota Tayoko 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 (70353670)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 流域水収支 / 蒸発散量 / 年輪 / 酸素同位体比 / 炭素同位体比 / 水利用効率

Outline of Final Research Achievements

Evapotranspiration (precipitation-discharge) estimated by water budget method has decreased at the Kamabuchi Experimental Watershed in Yamagata prefecture. Temperature has increased, and this might work to increase precipitation and discharge in this watershed area. Vapor pressure deficit and solar radiation have increased, this probably work to increase evapotranspiration. On the other hand, intrinsic plant water use efficiency (iWUE) calculated using δ13C of tree-ring cellulose has increased. The increase in iWUE probably is not caused by drought stress in this humid area, but the increase in the concentration of CO2 in the atmosphere. Although there is a physical effect of solar radiation and vapor deficit on evapotranspiration, the increase in atmospheric CO2 concentration leads to an increase in iWUE and a consequently causes long-term trend of evapotranspiration in this watershed.

Free Research Field

森林水文学

Academic Significance and Societal Importance of the Research Achievements

森林からの蒸発散量は伐採、樹木の成長、気候変動に応答して変化し、水資源量に影響を及ぼす。森林からの蒸発散量は二酸化炭素の増加にともなう気温の上昇や降水量の増加など物理的な気候変動の影響のみならず、樹木の生理学的な影響を受けて変化する。これまで森林水文学では水収支の一項目としての蒸発散量に対する気候変動の影響について、物理的な影響を調べることが多く、生理学的な影響を考慮してこなかった。本研究では蒸発散量に対する気候変動の物理的および植物生理学的な影響を明らかにする。このことは、将来的な水資源量の変動予測に役に立つ。