Bangkok, Thailand
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Ishida A.,Japan Forestry and Forest Products Research Institute | Ishida A.,Kyoto University | Harayama H.,Japan Forestry and Forest Products Research Institute | Yazaki K.,Japan Forestry and Forest Products Research Institute | And 6 more authors.
Tree Physiology | Year: 2010

This study compared leaf gas exchange, leaf hydraulic conductance, twig hydraulic conductivity and leaf osmotic potential at full turgor between two drought-deciduous trees, Vitex peduncularis Wall. and Xylia xylocarpa (Roxb.) W. Theob., and two evergreen trees, Hopea ferrea Lanessan and Syzygium cumini (L.) Skeels, at the uppermost canopies in tropical dry forests in Thailand. The aims were to examine (i) whether leaf and twig hydraulic properties differ in relation to leaf phenology and (ii) whether xylem cavitation is a determinant of leaf shedding during the dry season. The variations in almost all hydraulic traits were more dependent on species than on leaf phenology. Evergreen Hopea exhibited the lowest leaf-area-specific twig hydraulic conductivity (leaf-area-specific Ktwig), lamina hydraulic conductance (K lamina) and leaf osmotic potential at full turgor (Ψo) among species, whereas evergreen Syzygium exhibited the highest leaf-area-specific Ktwig, Klamina and Ψo. Deciduous Xylia had the highest sapwood-area-specific Ktwig, along with the lowest Huber value (sapwood area/leaf area). More negative osmotic Ψo and leaf osmotic adjustment during the dry season were found in deciduous Vitex and evergreen Hopea, accompanied by low sapwood-area-specific Ktwig. Regarding seasonal changes in hydraulics, no remarkable decrease in Klamina and Ktwig was found during the dry season in any species. Results suggest that leaf shedding during the dry season is not always associated with extensive xylem cavitation. © The Author 2010. Published by Oxford University Press. All rights reserved.


Ishida A.,Kyoto University | Yamazaki J.-Y.,Toho University | Harayama H.,Japan Forestry and Forest Products Research Institute | Yazaki K.,Japan Forestry and Forest Products Research Institute | And 8 more authors.
Tree Physiology | Year: 2014

In tropical dry forests, uppermost-canopy leaves of evergreen trees possess the ability to use water more conservatively compared with drought-deciduous trees, which may result from significant differences in the photoprotective mechanisms between functional types. We examined the seasonal variations in leaf gas exchange, chlorophyll fluorescence and the amounts of photosynthetic pigments within lamina of the uppermost-canopy leaves of three drought-deciduous trees (Vitex peduncularis Wall., Xylia xylocarpa (Roxb.) W. Theob., Shorea siamensis Miq.), a semi-deciduous tree (Irvingia malayana Miq.) and two evergreen trees (Hopea ferrea Lanessan and Syzygium cumini (L.) Skeels) in Thailand. Area-based maximum carbon assimilation rates (Amax) decreased during the dry season, except in S. siamensis. The electron transport rate (ETR) remained unchanged in deciduous trees, but decreased during the dry season in evergreen and semi-deciduous trees. In the principal component analysis, the first axis (Axis 1) accounted for 44.3% of the total variation and distinguished deciduous from evergreen trees. Along Axis 1, evergreen trees were characterized by a high Stern-Volmer non-photochemical quenching coefficient (NPQ), high xanthophyll cycle pigments/chlorophyll and a high de-epoxidation state of the xanthophyll cycle, whereas the deciduous trees were characterized by a high ETR, a high quantum yield of PSII (ΦPSII = (Fm ′ - F)/Fm ′) and a high mass-based Amax under high-light conditions. These findings indicate that drought-deciduous trees showing less conservative water use tend to dissipate a large proportion of electron flow through photosynthesis or alternative pathways. In contrast, the evergreens showed more conservative water use, reduced Amax and ETR and enhanced NPQ and xanthophyll cycle pigments/chlorophyll during the dry season, indicating that down-regulated photosynthesis with enhanced thermal dissipation of excess light energy played an important role in photoprotection. Trees with different water uses and leaf lifespans appear to employ different photoprotective mechanisms to overcome the unfavorable dry-season drought. Our data may suggest that future changes in precipitation will strongly impinge on forest structure and functions. © 2013 The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.


Johnson S.,University of Maryland University College | Lenz M.,CSIRO | Vongkaluang C.,1 Phaholyathin Ladyao Jatujak | Chutibhapakorn S.,1 Phaholyathin Ladyao Jatujak | And 2 more authors.
Sociobiology | Year: 2010

We collected two-hundred and eighty-four termites identified as the rare, relict genus Archotermopsis (Termopsidae) from one fallen log of Toona ciliata in a mixed deciduous forest at approximately 1500 m elevation in Doi Phu Ka National Park, Nan Province, Thailand in February of 2008. Among them was the first neotenic pair ever recorded for this genus. The neotenics exhibit much greater gonad development than other individuals collected with them. Gonad development of neotenics and helpers is similar to those in the closely-related species Zootermopsis nevadensis (Hagen), as is mandible development in the neotenics. These results suggest that not all individuals of the genus Archotermopsis have fully-developed gonads, as was recorded in Imms' 1919 monograph on Archotermopsis wroughtoni, though it is unclear if this difference in gonad development is due to seasonality.

Loading 1 Phaholyathin Ladyao Jatujak collaborators
Loading 1 Phaholyathin Ladyao Jatujak collaborators