Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG40] Material Circulations in Land Ecosystems

Thu. May 24, 2018 10:45 AM - 12:15 PM 106 (1F International Conference Hall, Makuhari Messe)

convener:Tomomichi Kato(Research Faculty of Agriculture, Hokkaido University), Takashi Hirano(Research Faculty of Agriculture, Hokkaido University), Hisashi Sato(海洋研究開発機構 地球表層物質循環研究分野, 共同), Ryuichi Hirata(National Institute for Environmental Studies), Chairperson:Sato Hisashi(JAMSTEC)

10:45 AM - 11:00 AM

[ACG40-01] An examination of water, energy, and carbon cycles in a subtropical evergreen broadleaf forest in Okinawa, Japan

*Kazuho Matsumoto1, Shingo Taniguchi1, Yu Miyagi2, Kei Terasawa3, Yasunori Yoshino4, Mayo Hayamizu4, Atsushi Takashima1 (1.Faculty of Agriculture, University of the Ryukyus, 2.Okinawa Prefecture, 3.Climatec, Inc., 4.Graduate School of Agriculture, University of the Ryukyus)

Keywords:Evapotranspiration, Respiration, Subtropical forest

To examine water, energy, and carbon cycles in a subtropical forest ecosystem, we established a long-term ecosystem-monitoring site in a mature evergreen broadleaf forest in northern Okinawa Island in 2013. Using eddy covariance, chamber-based, and biometric methods, we collected data describing the unique characteristics of this subtropical forest. The total biomass of this forest was small as a mature broadleaf forest in Japan. However, annual evapotranspiration values were comparable to those of tropical rainforests due to the substantial precipitation, a moderate climate even in winter, and unique forest structure. Latent heat flux was also very high; in winter, all available energy was consumed as latent heat flux. Both carbon assimilation and ecosystem respiration were high, and these values were comparable to those of tropical forests. Half of the net primary production became necromass (litterfall and dead trees) due to frequent disturbance by typhoons, and carbon was released rapidly through heterotrophic respiration. Since increases in biomass were offset by necromass decomposition, it was suggested that net ecosystem production in this forest was very small.