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Nighttime transpiration observed over a larch forest in Hokkaido, Japan
Author(s) -
Kobayashi N.,
Hiyama T.,
Fukushima Y.,
Lopez M. L.,
Hirano T.,
Fujinuma Y.
Publication year - 2007
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005556
Subject(s) - larch , canopy , transpiration , environmental science , understory , canopy conductance , atmospheric sciences , growing season , vapour pressure deficit , agronomy , photosynthesis , ecology , botany , biology , geology
Nighttime transpiration in a larch forest in northern Japan was investigated using concurrent measurements of the energy budget below and above the canopy and sap flow velocities. Upward latent heat flux ( lE ) above the canopy was observed on ∼20% of nights during the growing season. Nighttime lE was ∼7% of daily totals during the dry season (September–October) and averaged ∼3% over the entire growing season. A relatively low contribution of the understory to lE (<30%) and strong synchronicity between larch sap flow rates and lE on two warm windy nights indicated nighttime lE , occurring when warm dry air intruded from above, was largely due to transpiration from the larch overstory. High canopy conductance on some nights relative to reported maximum cuticular conductance and a strong correlation between canopy conductance and air humidity on these nights indicate the stomata of the larch trees did not close tightly at night.