Abstract
As a method for monitoring the vigor of planted forest community, we examined the spectral light intensity inside and outside the community by a photometer and a experimental detector of vegetation index. By mesuring the spectral intensity and checking an optical model, it is concluded that ambient light inside the community is more sensitive than reflected light outside the community, and near infrared spectrum is also more sensitive than red spectrum to detect the variation of LAI of the community. Vegeation indexes, such as R/IR and NDVI, derived from the light inside the community is also useful as for the reflected light for the forest vigor monitoring.
