抄録
Most of Japanese young plantation forests have reached an age when thinning is needed, but they have not yet been cut, and stand density is often too high. An economical method is needed for selecting stands that should be cut. We are developing a method of stand density estimation using aerial photography. In previous work, we devised a method for high resolution color aerial-photographs. It divides images into a series of color bands, and estimates stand densities by the brightness in a combination of different band images. Ground truthing is needed to improve precision. In our earlier work, we used a set of 22 plots for ground truthing. Here, we present ground truthing of mono-color aerial photographs obtained for a growing stock investigation project in Ehime prefecture, Japan. The project is to estimate the CO_2 sink potential for all forests in the prefecture. Vegetation profiles are measured by airborne laser altimetry assisted by a consecutive series of ground truth surveys. Performance of mono-color aerial photography method was rather poor, indicating that manual contrast adjustment should be improved.
