Evapotranspiration from understory vegetation in an eastern Siberian boreal larch forest

We measured evapotranspiration in an eastern Siberian boreal forest, in which the understory was cowberry and the overstory was larch, during the entire growing seasons of 2005 and 2006. We compared evapotranspiration from the understory vegetation above the forest floor E U with evapotranspiration...

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Bibliographic Details
Published in:Agricultural and forest meteorology 2009-06, Vol.149 (6), p.1129-1139
Main Authors: Iida, Shin’ichi, Ohta, Takeshi, Matsumoto, Kazuho, Nakai, Taro, Kuwada, Takashi, Kononov, Alexander V., Maximov, Trofim C., van der Molen, Michiel K., Dolman, Han, Tanaka, Hiroki, Yabuki, Hironori
Format: Article
Language:English
Subjects:
Aerodynamic conductance
boreal forests
Deciduous larch
Decoupling coefficient
evapotranspiration
Evergreen understory vegetation
forest ecosystems
forest soils
forest trees
growing season
hydrologic cycle
Larix
Larix cajanderi
leaf conductance
plant physiology
seasonal variation
shrubs
Surface conductance
understory
Vaccinium vitis-idaea
vapor pressure
water vapor
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Summary:We measured evapotranspiration in an eastern Siberian boreal forest, in which the understory was cowberry and the overstory was larch, during the entire growing seasons of 2005 and 2006. We compared evapotranspiration from the understory vegetation above the forest floor E U with evapotranspiration from the whole ecosystem above the overstory canopy E O. The E U/ E O ratio had a seasonal trend with a flat-bottomed U-shape during the growing season (4 May–30 September). High- E U/ E O ratios at the beginning and end of the growing season were observed because larch, one of the two sources of E O, was a deciduous tree, while the understory was the evergreen cowberry. The mean daily E U values during the foliated period of larch (1 June–31 August) were 0.8 and 0.9 mm day −1, or 51.4 and 51.8% of E O in 2005 and 2006, respectively. The understory vegetation was one of the most important components of the hydrologic cycle in this forest. A significant amount of E U was caused by plant physiological control, due to the aerodynamic conductance, which was much larger than the surface conductance, leading to a smaller decoupling coefficient. We found that 71% of E U was caused by the vapour pressure deficit above the forest floor.
ISSN:0168-1923
1873-2240
DOI:10.1016/j.agrformet.2009.02.003