Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

A (Atmospheric and Hydrospheric Sciences) » A-HW Hydrology & Water Environment

[A-HW22] Hydrological Cycle and Water Environment

Thu. May 24, 2018 9:00 AM - 10:30 AM 104 (1F International Conference Hall, Makuhari Messe)

convener:Seiya Nagao(Institute of Nature and Environmental Technology, Kanazawa University), Isao Machida(Geological Survey of Japan), Shin'ichi Iida(国立研究開発法人森林研究・整備機構森林総合研究所森林研究部門森林防災研究領域水保全研究室, 共同), Takeshi Hayashi(Faculty of Education and Human Studies, Akita University), Chairperson:Hayashi Takeshi(Faculty of Education and Human Studies, Akita University), Iida Shin'ichi(Forestry and Forest Products Research Institute), Machida Isao(Geological Survey of Japan, AIST), Nagao Seiya(Institute of Nature and Environmental Technology, Kanazawa University)

9:15 AM - 9:30 AM

[AHW22-08] Transpiration from cedar (Cryptomeria japonica) trees under snow cover in a heavy snowfall area, Shonai, Japan.

*Maximo Larry Lopez caceres1, Takahiro Osonoi1, Yoshihiro Iijima2 (1.Faculty of Agriculture, Yamagata University, 2.Faculty of Bioresources, Mie University)

Keywords:sap flow, snowmelt, snow cover, soil temperature, transpiration

Forest in heavy snowfall areas in northeastern Japan are constrained by periods of snow cover in early spring that extend longer than the onset of suitable atmospheric conditions for the start of transpiration and photosynthesis. In this study we measured sap flow in cedar trees (Cryptomeria japonica) together with tree growth, snow depth, soil temperature and environmental parameters to determine the timing of the start of transpiration and evaluate the contribution of snowmelt on tree transpiration. The results showed that tree sap flow started by mid March when snow depth was approximately 2.2 m and soil temperature was nearly 0°C. However, based on the ranges of optimum air temperatures for the start of photosynthesis we estimated that transpiration started by mid-April and tree growth started by the end of April when soil temperature increases sharply as snowmelt is complete and there is no limitation for tree water uptake. Soil moisture increased steadily from the end of March but it increased drastically in April along with the snowmelt rate. Thus, by May, the driest month of the year, soil water, which was originated from previous year rainfall was replaced by snowmelt water and therefore in May contributed to transpiration when tree-ring formation started. Further, δ18O analysis will be used to determine to what extent snowmelt water was used in wood formation.