NAME =  Mie Miyahara  
ORGANIZATION =  Graduate School of Bioagriculture, Nagoya University  
ADDRESS =  Furo-cho, Chikusa-ku, Nagoya 464-8601  
COUNTRY =  Japan  
PHONE =  052-789-4052  
FAX =  052-789-4055  
E-MAIL =  i031038m@mbox.nagoya-u.ac.jp  
POSTER_ONLY =  no  
THEME =  T1  
DATE =  30-Jul-04-23:11:36  
ABSID = T1MM30Jul04231136 
TITLE = Contribution of cowberry transpiration to evapotranspiration in larch forest 
AUTHOR_1 = Mie Miyahara 
INSTITUTION_1 = Graduate School of Bioagriculture, Nagoya University 
PRESENTER = AUTHOR_1 
AUTHOR_2 = Chisato Takenaka 
INSTITUTION_2 = Graduate School of Bioagriculture, Nagoya University 
AUTHOR_3 = Takashi Kuwada 
INSTITUTION_3 = CREST, Japan Science and Technology Agency(JST) 
AUTHOR_4 = Takeshi Ohta 
INSTITUTION_4 = CREST, Japan Science and Technology Agency(JST),    Graduate School of Bioagriculture, Nagoya University 
AUTHOR_5 = Trofim C. Maximov 
INSTITUTION_5 = Institute for Biological Problems of the Cryolithozone, Siberian Division of Russian Academy of Sciences, Yakutsk 677891, Russia 
ABSTRACT =   Forests in Eastern Siberia are dominated by deciduous conifer tree, Larch (Larix cajanderi), known as light taiga. In mature larch forest, the overstory is very sparce, so the forest floor is covered with cowberry (Vaccinium vitis -Idea) due to its light environment. Since cowberry is evergreen species and its LAI is estimated about 2.5(Hamada et al, 2004), it is considered that cowberry should contribute significantly to water cycle in larch forest. From the results of recent examination, the contribution of understory evapotranspiration to the entire larch forest's one is estimated 25 to 50%(Hamada et al, 2004). However, field observation data on the role of cowberry in larch forest has been little.
  The purpose of this study is to quantify contribution of cowberry transpiration to larch forest evapotranspiration.
  Observation was conducted in 2003 and 2004 in larch forest at Spasskaya Pad, located about 20km north of Yakutsk in eastern Siberia, where the stand density is 840 trees ha-1. We measured transpiration rate of cowberry using a infrared gas analyzer, LI-6400. Soil moisture at 10cm depth was monitored using TDR in two different sites where one is covered with cowberry and another was removed cowberry. 
The results showed that the soil moisture in the cowberry site fluctuated day by day, in contrast, it kept constant in the no-cowberry site. Besides, it is recognized that there is complementary relationship between diurnal variations of soil moisture and transpiration rate of cowberry. Therefore, cowberry transpiration strongly affects moisture condition of soil surface. We found that the latent heat flux by transpiration of cowberry occupied more than 80% in the early stage leaf development of larch, and 30 to 50% during the growing season, by analyzing the seasonal variation of latent heat flux.
  These results indicate that cowberry plays an important role in water cycle in larch forest and its contribution depends on phenology of larch.