Estimation of stand volume by fusing low laser-sampling density LiDAR data with QuickBird panchromatic imagery in closed-canopy Japanese cedar (Cryptomeria japonica) plantations

This study investigated the potential of fusing low laser-sampling density LiDAR data with QuickBird panchromatic imagery for estimating stand volumes. The study area was in closed-canopy, mountainous Japanese cedar (Cryptomeria japonica) plantations in Japan. Stand volume in the area ranged from 250.5 to 913.1 m/ha and terrain was undulating with an elevation ranging from 135 to 391 m above sea level. A total of 13 circular sample plots (0.04 ha) were established and stand volume within the plots was measured as validation data for evaluating stand volume estimates derived from the fused data through a regression model. The independent variables of the empirical model were individual tree height and crown projection area and the dependent variable was individual stem volume of Japanese cedar. To estimate stand volume with the fused data, LiDAR-derived tree heights and panchromatic imagery-derived crown projection areas were computed for individual tree crowns delineated by the Voronoi tessellation. All results of this study revealed that fusing low laser-sampling density LiDAR data (e.g. 1 point/4 m) with QuickBird panchromatic imagery (0.6-m resolution) would have great potential to estimate stand volume precisely in Japanese cedar plantations regardless of different footprint sizes (e.g. 0.16–0.47 m).