Abstract
Todevelop a monitoring system for carbon sinks under the Kyoto Protocol, a method of forest stand measurement using Airborne Lidar sensor is examined. A canopy DSM (Digital Surface Model) was constructed from first pulse of the lidar data, and the DTM (Digital Terrain Model) was constructed from the last pulse of the lidar data. The tree height surface was made from the difference of the canopy DSM and DTM. Crowns of trees were extracted from the tree height surface by the Watershed method. Numbers of stand trees were counted from the crowns. Tree heights were measured from height surface within the crown. Stem volumes of trees were calculated from the relationship between tree height and stem volume, from a yield-density effect curve, and from an aerial photographical analysis table. Carbon weights were calculated by using the relationship between the stem volumes and dry weights and the coefficient of carbon inclusion.
The results are : 1) The measurement error of tree height of Larix leptolepis stand was less than about 0.3 m (accuracy) and 1.0 m (precision). The precision of the measurement was assumed to be originated from the precision of truth data ; 2) the extracted crowns of trees were canopy trees, not understory trees, and the number of extracted crown had a tendency to be underestimated ; 3) stem volumes and carbon weights were underestimated by using the relationship between the tree heights and stem volumes and the yield-density effect curve. Using aerial photographical analysis table, however, yielded better results.
The next steps of this study will be 1) to develop of a method of the extraction technique from the lidar points with more accuracies, and 2) to develop of a method of aerial photographical analysis to estimate carbon weights for wide areas.
