Abstract
In natural woody conditions, measuring tree position and diameter at breast height (DBH) of each Larix leptolepis by a portable scanning lidar is not easy because the tree is covered with not only their own thick branches but also other plants such as small broad-leaved trees, vines, epiphytes and quite tall ferns. Therefore, new methods for mapping tree position of Larix leptolepis woods and estimating the DBH using the range data of measurable tree parts obtained by a portable scanning lidar with high spatial resolution were examined. Furthermore, biomass of the trees was estimated from the DBH.
Using the range data measured by the portable scanning lidar that was set at a point in the woods, each tree position was mapped. Within the area of the angle of 170 degrees horizontally and 10m from the lidar, the number of measurable trees was 14 (100% of all trees in the area), within the area of 15m the number was 24 (83%), within the area of 20m the number was 29 (66%), and within the area of 30m the number was 44 (45%). Then the DBH of each tree was estimated in error of RMSE=7.3mm from the trunk diameter measured at a certain height of the tree using Eq. (1), where the coefficient k (h) had been obtained beforehand. Also, the biomass (fresh, dry and carbon weight) of each tree was estimated from the DBH using a quadratic equation (R2=0.96) correlated between DBH and biomass above ground. Furthermore, the biomass per square meter was estimated in error of 2.7% within the area of 30m from the lidar. The fresh weight and the carbon weight were obtained from the dry weight multiplied by 1.7 and 0.45 respectively.
