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| Titel |
Inter- and intra-annual variations of transpiration at a rubber stand in lowland of central Cambodia |
| VerfasserIn |
Nakako Kobayashi, Tomo'omi Kumagai, Yoshiyuki Miyazawa, Kazuho Matsumoto, Makiko Tateishi, Lim Khan Tiva, Ryan Mudd, Thomas Giambelluca, Yin Song |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077754
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| Zusammenfassung |
| In Southeast Asia, rubber plantation is rapidly expanding, and thus understanding the level of
water consumption and tree physiology is a matter of importance to know the impacts on the
local hydrology. Intra- and inter-annual variations in transpiration rate (Et) at a rubber
stand, growing in lowland of central Cambodia, were examined during two years
based on sap flow measurements. As for seasonality, Et was generally large in
the rainy season and small in the dry season, showing sharp short-time drop in
synchronization with the shedding in late January. Daily stand Et was ~ 2.0 mm day-1 in
2010 and ~ 2.4 mm day-1 in 2011 at the maximum. An analysis of non-linear
multiple regression for the canopy conductance (gc) in the two years showed that
the stomatal response of rubber trees was well explained by the changes in solar
radiation, vapour pressure deficit, soil moisture availability, leaf area, and tree diameter.
Sensitivity of gc to the atmospheric drought indicates isohydric behavior of rubber
trees, while the same analysis for each year showed possibility of change in leaf
characteristics due to tree maturity and/or initiation of latex tapping. The best fit model also
predicted relatively small sensitivity of gc to the soil moisture deficit and rapid decrease
in gc under extreme drought conditions. Annual stand Et estimated with the gc
obtained in the present analysis was 469 mm yr-1 in 2010, while it increased up to
658 mm yr-1 in 2011. To find out the most important environmental variables,
we examined the effect of each variable by keeping the others unchanged. This
hypothesis analysis showed that in the young rubber stand which were growing
very rapidly, inter-annual change of stand Et was determined mainly by the tree
growth rate, not by the change of surrounding environments in the air and the soil. |
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