Estimation of Tree Stem Diameters and Biomass in Japanese Cedar Forest Using Portable Imaging Lidar Data

抄録

　Estimation of carbon sinks in forest is important to understand global climatic changes such as global warming. The amount of carbon sinks is often explained by biomass, which can be calculated by DBH (Diameter at Breast Height) of each tree. However, measuring exact DBH of standing trees by existing methods is tedious and takes longer time. Hence, studies have been carrying on developing the methodology to measure DBH and biomass.
　In　this　study,　a　ground-based　remote　sensing　technique　to　measure　tree　stem　diameters　and　biomass　in　forest has been developed using portable imaging lidar data. Forty 60-year-old Japanese cedars (Cryptomeria japonica) in a study site of 400 m² were measured to estimate DBH and biomass (carbon weight).
　As a result, each DBH of 31 trees (other 9 are in dead angle) was measured with RMSE (Root Mean Square Error) of 6.1 mm. The biomass of individual tree was calculated with RMSE of 11.5 kgC. Total biomass in entire study site including 9 trees in dead angle was estimated by percent method within the error of 3%. It can therefore be concluded that the methodology using a lidar can efficiently replace existing methods to measure DBH and carbon sinks with high accuracy.