Premium
Influence of evaporation from the forest floor on evapotranspiration from the dry canopy
Author(s) -
Daikoku Kenichi,
Hattori Shigeaki,
Deguchi Aiko,
Aoki Yu,
Miyashita Mari,
Matsumoto Kazuho,
Akiyama Junichi,
Iida Shinichi,
Toba Tae,
Fujita Yuji,
Ohta Takeshi
Publication year - 2008
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.7010
Subject(s) - canopy , evapotranspiration , environmental science , bowen ratio , leaf area index , diurnal temperature variation , vapour pressure deficit , atmospheric sciences , understory , evaporation , forest floor , potential evaporation , water content , hydrology (agriculture) , transpiration , soil water , agronomy , soil science , ecology , botany , geology , photosynthesis , biology , meteorology , geography , geotechnical engineering
Evaporation from the forest floor ( Ef ) of a secondary broad‐leaved forest was monitored for 1 year at 30 min intervals using a closed chamber system. The diurnal and seasonal variation of Ef and forest structure were analysed for days undisturbed by rainfall. The diurnal change in Ef reached a maximum at about 14:00 and gradually decreased towards midnight along with the vapour pressure deficit ( D ). Although Ef comprised about 20% of evapotranspiration from the dry canopy ( Et ), it had only a small influence on diurnal evaporation efficiency (β) characteristics above the canopy because its diurnal range was much smaller than that of Et . Although leaf emergence and leaf fall clearly affected available energy ( Ae ) beneath the canopy, the influence was not clear with Ef . In contrast, seasonal variation in Ef was strongly correlated with D and Ae above the canopy, and the determination coefficient ( R 2 ) changed with the Bowen ratio ( B ). At night, Et was almost equal to Ef when the friction velocity ( u *) ranged between 0·2 and 0·4 m s −1 . The ratio of Ef to Et was exponentially correlated with leaf area index ( LAI ) when the soil was not dry. The ratio of Ef to Et was mainly influenced by LAI and soil moisture, but the existence of understory vegetation did not have a strong influence. Copyright © 2008 John Wiley & Sons, Ltd.