Keywords :
Tropical dendrochronology,
Vessel traits,
Stable carbon isotope,
Tropical seasonal forest,
Leguminosae
บทคัดย่อ :
Recently several methods to detect tree rings in tropical tree
species have been reported, but each method still needs
improvement in terms of accuracy, cost, effort and
applicability to species and region. This paper proposes an
easier and more reliable method based on wood anatomy.
Wood core samples were collected from five Leguminosae
species growing in either plantations or seasonally dry forests
in northeast Thailand. The species sampled were: Afzelia
xylocarpa, Dalbergia cochinchinensis, Pterocarpus
macrocarpus, Sindora siamensis and Xylia xylocarpa. All
species had relatively distinct axial parenchyma bands in their
cross sections, with P. macrocarpus being semi ring-porous
and the others diffuse-porous species. Radial variations of
vessel traits (mean vessel lumen area, proportion of vessel
lumen area and vessel frequency) were measured and
compared with the carbon isotope compositions ( 13C) of the
holocellulose extracted from the same wood sample. All
species showed cyclical variations in the vessel traits and
correlations with the 13C values, but the correlation
coefficient of each vessel trait with the 13C values varied
species by species. The axial parenchyma bands observed in
cross sections were not formed regularly in most of the
species, because two or more bands were sometimes observed
during one cyclical change in the vessel traits and 13C values.
Only A. xylocarpa appeared to form parenchyma bands
regularly. The results showed that the vessel traits are more
reliable indicators of growth rings than the visible bands of
the xylem. Furthermore, the correlations between the vessel traits and the 13C values emphasized that the vessel
anatomical method was capable of detecting growth rings,
which supported the conclusion that measuring vessel traits
had a great potential for tropical dendrochronology within
regions having a seasonal climate.
เอกสารอ้างอิง :
Ohashi, S., Okada, N., Siripatanadilok, S., & Veenin, T. (2009a). Detecting tree rings of Leguminosae in tropical seasonal forests by wood anatomy. In The proceedings of the FORTROP II International Conference (Vol. 2, pp. 1-13).
