Physiological responses of eastern Siberian boreal larch and pine to the environmental factors at the leaf and canopy scale
Takashi KUWADA (1), Takeshi OHTA (2), Ken YOSHIKAWA (3)
(1) Japan Science and Technology Agency
(2) Graduate School of Bioagricultural Sciences, Nagoya University
(3) Faculty of Agriculture, Okayama University
Stomata play an important role that links regional and global climate with water, carbon and nutrient cycles by controlling the water movement from the soil through the plants to the atmosphere. In order to predict the effect of the global climate change, it is necessary to improve our understanding of stomatal response to the environmental changes and the subsequent changes in evapotranspiration from the various ecosystems. However, there is little information about the relationships between the leaf-level stomatal response and canopy-level stomatal response to the environmental factors, which forms the basis for up-scaling physiological process in time and space. We analyzed the data obtained at eastern Siberian boreal larch and pine forest using big-leaf model including the Jarvis type conductance model. These forests have relatively low leaf area index and more direct sunlight reaches their understory. Therefore, there is a significant contribution of the understory vegetation to the forest evapotranspiration. The parameters of the conductance model related with the short wave radiation, air temperature and vapor pressure deficit of the air (VPD) were fitted. In both of larch and pine, the maximum canopy stomatal conductance was 6 to 7 times greater than the maximum stomatal conductance. The stomatal conductance reached saturated values at the lower short-wave radiation condition as compared to the canopy stomatal conductance. Canopy stomatal conductance showed lower optimal temperature for evapotranspiration compared with the stomatal conductance. In case of pine, canopy stomatal conductance decreased more sharply with VPD than the stomatal conductance. It is suggested that different environmental controls of evapotranspiration existed in these two forests.
Submittal Information
Name :
Date :
Takashi KUWADA
30-Jul-04-13:56:57
Organization :
Theme :
Japan Science and Technology Agency
Theme 5
Address :
Presentation :
Laboratory of Forest Meteolorogy and Hydrology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601