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Intra- and interspecies differences in transpiration in a lowland deciduous forest in Cambodia

Iida, S., Shimizu, T., Tamai, K., Ito, E., Kabeya, N., Shimizu, A., Ohnuki, Y., Keth, N., Chann, S.
Acta horticulturae 2013 no.991 pp. 417-423
deciduous forests, dry season, ecosystems, hydrology, leaves, lowland forests, lowlands, monsoon season, temporal variation, transpiration, trees, wet season, Cambodia, Indochina
Cambodia still retains natural forests in the lowland plains even while this biome has been vanishing from lowland areas in other countries along the Indochina Peninsula. Few studies have described the hydrologic and ecological processes in this ecosystem, especially in deciduous forests, which occupy the highest percentage of total forested area in Cambodia. To determine intra- and interspecies differences in transpiration in a lowland deciduous forest in Cambodia, we measured single-tree transpiration using the Granier method for 12 trees of four species. Cambodia is located in the Asian monsoon region and experiences distinct wet and dry seasons. We detected larger intra- and interspecies differences in transpiration during leaf fall and foliation, both of which occurred in the dry season. The timing of when leaf fall was complete and transpiration ceased varied intra- and interspecies, often differing up to 1 month. We confirmed that trees began leaf flush during the dry season, at least 1 month before the first monsoon rains and during the driest part of the year. In contrast, relatively small intra- and interspecies differences in the temporal patterns of transpiration were observed during the foliated period, which primarily coincided with the wet season. The amount of transpiration was linearly related to the crown projection area that was unshaded by the crowns of other trees; i.e., tree-to-tree differences in transpiration were probably caused by differences in light conditions.