Experimental study on utilization of remote sensed data for assessing ecophysiological condition of vegetation

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In order to establish the methodology for assessing ecophysiological conditions of vegetation using remote sensing technique, field and laboratory experiments were conducted to clarify the relationship between characteristics of photosynthetic behavior and properties of spectral reflectance in leaf and canopy scale. The field experiments were conducted at the Kiryu Experimental watershed in Shiga prefecture and the Akoh experimental site in Hyogo prefecture. Multi-seasonal CO_2/H_2O flux observations were carried out using eddy correlation method with various micro meteorological measurements in the Kiryu sites. Based on the experimental results in this observation, a big leaf type numerical model describing the CO_2/H_2O exchanges between canopy and atmosphere was developed, The model could reasonably estimate the seasonal variations of heat, vapor and CO_2 fluxes, and could calculate the annual assimilation rate of forest stands. The flux observations in the Akoh site were conducted focusing on the influences of canopy structure. The model developed for this experiments can predict the vertical distributions of radiation, wind speed, heat, CO_2 and H_2O fluxes. The laboratory experiments were operated on several broad-leaf evergreen trees planted in pots using a high-resolution multi-spectral meter and a portable photosynthesis meter. The results shows that the NDVI derived from spectral reflectance of leaves did not always correspond to photosynthetic behaviors, This suggests that utilization of the far infrared reflectance as a surface temperature index is required to sense remotely the real-time responses of photosynthesis even for individual leaf scale.