|| 要旨トップ | 目次 |||日本生態学会第63回全国大会 (2016年3月、仙台) 講演要旨
一般講演（口頭発表） E1-15 (Oral presentation)
Evapotranspiration (ET) from tropical rainforests has an important role in the regional and global water cycling. However, the component fluxes of ET remain unquantified. Quantifying contribution of individual trees to stand transpiration (Esta) will advance our understanding of the sources of spatial variation of ET. The aim of this study is to answer a basic question: Do few large trees contribute more to Esta than the numerous small individuals?
Tree transpiration was measured in three plots in Lambir Hills National Park. Depending on tree size, two or four fixed sensors were installed in the stems to account for azimuthal variation of sapflux density (Fd). Also, a moving probe was used to evaluate radial variation of Fd.
No clear azimuthal pattern of Fd was identified, but Fd decreased with increasing sensor depth. Because inter-tree variation of hydroactive xylem area was greater than that of their Fd, tree transpiration increased linearly with basal area. The largest 15% of samle trees accounted for 61% of Esta. Therefore, in stands of similar diameter-distribution, a few large individuals disproportionately contribute to Esta.