Abstract
As one of the method for estimating the the amount of leaves and forest vigor, we examined the usefulness of the properties of light spectrum obtained from the measurement of canopy reflectance and transmittance into the floor of model forests consisting of 3-year old Quercus glauca THUNB. We analized the changes of spectral curve in the visible and near-infrared wavelength and (VI) derived 6 Vegetation Indices from spectral data. From regulation analysis results VIs derived from transmittance were more positively related to LAI variations than VIs from reflectance under dense canopy. This means that transmittance is more sensitive to the LAI variation than reflectance. We also found that changes of VIs, such as R/NIR and ND VI, derived from transmittance, were linearly related to decline in vigor caused by water stress. These results confirm that the properties of transmitted spectrum could be more useful for estimation of LAI and the vigor of forests than reflected spectrum, and VIs derived from the transmitted light inside the forest should be useful as a new method for monitoring forests, and contribute to studies for developing new methods.
