Abstracts for the 6th International GAME Conf.

3-5 December 2004

Kyoto Japan

Spatial variations of the parameters of canopy conductance model in forests from the mid- to high-latitude area

Takeshi OHTA (1), Takashi KUWADA (2), Shuko HAMADA (3), Jumpei KUBOTA (4)

The physiological responses on environmental factors of forests are important to understand the effects of vegetations on the water cycle, and it is needed to clarify the spatial differences of forest effects on the water cycle. Many physiological models, for example SiB, SiB2 and so on, of vegetation are proposed to express the vegetation effects in Land Surface Models. The schemes of vegetated land surface processes are developing and a lot of resistances (or conductance) are included in a model. It will be difficult to examine the spatial variation of these parameters using such a kind of models. The spatial distribution of the physiological effects in forests on the water cycle is examined using the big-leaf model including the Jarvis type conductance model in this study. The dataset of latent heat flux and meteorological variables is obtained at the 17 flux stations, including the larch and the pine sites in the plain taiga and the pine site in the southern taiga of GAME-Siberia, located at from 35.133ßN to 64.117ßN. The parameters of the conductance model related with air temperature, saturation deficit in atmosphere and short-wave radiation are fitted. The climate datasets of annual mean temperature, annual precipitation and annual net all-wave radiation provided from IIASA and ISCCP are used to examine the relationship between the model parameters and climatic condition. The main results obtained from this analysis are as follows; (1) The forest canopy conductance in the colder regions shows lower optimal temperature for evapotranspiration, (2) The canopy conductance reaches saturated values at the lower short-wave radiation condition in the region where the annual short-wave radiation is low even when the atmospheric saturation deficit is high, (3) The canopy conductance in the drier region is kept at high values comparing with those in the humid regions, (4) The tendency between the canopy conductance and the climatic variables can be approximated by one relationship in spite of different vegetation types. These results suggest that the sensitivities of canopy conductance are affected by not only the vegetation (or forest) types but the climatic conditions in the area where the forest exists.

Submittal Information

Name : Date :
    Takeshi OHTA
    27-Jul-04-13:41:59
Organization : Theme :
    Graduate School of Bioagricultural Sciences, Nagoya University
    Theme 1
Address : Presentation :
    Furocho, Chikusa-ku, Nagoya, Acichi 464-860
    Poster or oral
Country : Abstract ID :
    Japan
    T1TO27Jul04134159
Phone : Fax :
    +81-52-789-4059
    +81-52-789-4059
E-mail :
    takeshi@agr.nagoya-u.ac.jp