Investigation of Measuring Accuracy of Forest Area by Means of Airborne Laser Scanner

It is an important subject to accurately measure forests that serve as sinks since the global warming is taken up as a serious problem in recent years. Tree height and so on have so far been measured by the conventional direct or indirect measuring method. Presently, however, the measuring accuracy by airborne laser scanner has been improved and it is now reaching the stage of practica l use for measuring forests as well. For this study, we selected the forest of Tama Forest Science Garden (Hachioji, Tokyo) of Forestry and Forest Products Research Institute as an investigation field where various types of trees grow and a database is constructed. Then we compared the data obtained with the laser scanner with the results of topographic survey and tree height measurement conducted at the investigation field of a specific range and investigated the accuracy of measuring the forest area. According to the verification result relating to the DEM accuracy, the error of the DEM made from the laser scanner to the actually measured value was about 50cm(min.). As a result of accuracy investigation of tree height, a large difference was found in measuring error depending on the growth condition of trees (tree shape). At a place where trees grow almost vertically, the difference between the DSM and tree height value actually measured was small. However, at places where trees grow obliquely or trees are intertwined in a complicated way, the measuring error was large.