ISOPRENE FLUX MEASUREMENT USING RELAXED EDDY ACCUMULATION METHOD IN WARM-TEMPERATE MIXED FOREST IN JAPAN

摘要

To estimate isoprene fluxes between the ecosystem and the atmosphere accurately, we utilized REA method to measure the isoprene fluxes between 2008 and 2009 in Yamashiro Experimental Forest, Kyoto, Japan. YEF is in a mixed temperate forest with Japanese oak; one of the major tree species in Japan. The oak is a strong isoprene emitter. The daily mean flux (7:00-18:30 LST) was the highest on July 23, 2009 of 2.7 ± 2.0 mgC m~(-2) h~(-1). The seasonal variations of daytime isoprene fluxes have a strong relationship with the daytime ambient temperature. When the leaves turned into yellow, the isoprene flux and concentration in the air were not detected. In order to estimate the ratio of the carbon reemitted by isoprene, the observed isoprene fluxes were compared with the observed CO_2 fluxes. The highest ratio was 2.3% observed on Aug. 22 in 2008.