Abstract
Crown density control is one of the main activities in forest management. For the prediction of tree growth, it is important to consider the crown length, leaf biomass, and other canopy parameters as a photosynthetic organ. We estimated the lengths of canopies on the basis of a Digital Surface Model (DSM) and Digital Elevation Model (DEM) obtained from airborne Light Detection and Ranging (LiDAR) data and examined the accuracy of the estimates in even-aged stands. Cryptomeria japonica and Chamaecyparis obtusa stands were selected for analysis. The study site was the University Forest in Chiba, Japan, which is managed by the University of Tokyo and has stand densities between 350 and 4,000 trees ha^<-1>. First, we calculated the DSM and DEM for the University Forest in Chiba for the analysis of canopy information. We established 12 circular sample plots in Cryptomeria japonica and Chamaecyparis obtusa stands and measured the crown length of the dominant trees in each plot. Second, we estimated the crown length of the dominant trees in each plot using the DSM and DEM obtained from airborne LiDAR data. Finally, we compared crown lengths obtained from airborne LiDAR data with crown lengths obtained from ground surveys and checked the accuracy of this methodology. The crown lengths obtained from airborne LiDAR data were highly correlated with those obtained from ground surveys (coefficient of determination=0.95; root mean square error (RMSE)=0.67). Thus, airborne LiDAR accurately measured crown length, regardless of stand density.
