HR: 0830h
AN: B11C-0706    [PDF]
TI: Radial Distribution of Photosynthetically Spiked Carbon-13 Tracer in a Tree Ring
AU: * Kagawa, A
EM: akagawa@ffpri.affrc.go.jp
AF: Forestry and Forest Products Research Institute, Tsukuba Norin P.O. Box 16, Tsukuba, 305-8687 Japan
AU: Sugimoto, A
EM: atsukos@ecology.kyoto-u.ac.jp
AF: Center for Ecological Research, Kyoto University, Kamitanakami, Hiranocho, Otsu, 520-2113 Japan
AU: Abe, H
EM: abeq@affrc.go.jp
AF: Forestry and Forest Products Research Institute, Tsukuba Norin P.O. Box 16, Tsukuba, 305-8687 Japan
AB: Among other stable isotopes, stable carbon isotope ratio in tree rings is most commonly used for reconstruction of precipitation, drought or soil water status. However, the time lag between carbon incorporation by photosynthesis and use of the assimilated carbon for xylem formation is poorly documented. For example, how much of the stored carbon assimilated at the end of growing season can be used for the following year's xylem growth is not well understood. Our objective was to clarify how carbon assimilated at a given time in different seasons (spring and summer) is used for succeeding xylem growth and eventually distributed radially in a tree ring. Using a 4-year old Japanese cedar tree (Cryptomeria japonica) growing in Tsukuba, Japan, we fed carbon isotope tracer (99 atom %) photosynthetically to the tree on May. 29 and Sep. 18 in 2001, and the tree was cut down in March 2002. At the same time, the cambium was pin-marked on Sep.18. Tangential sections of 60 æm thickness were cut continuously from the tree ring formed in 2001 with an ultra microtome. d13C was measured on both balk and holocellulose samples of these sections. Two peaks of d13C were detected in the tree ring, and the outer d13C peak corresponded to the location of pin-marking on Sep. 18. Small difference in d13C profile between bulk and holocellulose samples was observed at the first part (closer to the pith) of the peaks, probably reflecting lignification pattern.
DE: 1812 Drought
DE: 1833 Hydroclimatology
DE: 1851 Plant ecology
DE: 1866 Soil moisture
DE: 4870 Stable isotopes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting