Estimating Leaf Area Index in Mixed Forest Using an Airborne Laser Scanner

Leaf area index (LAI) is one of the most important parameter of forest structure. The study site was an isolated forest in Kyoto City in Japan and it vegetation type was mixed forest. We took fisheye photos at 102 points in the study area, and calculated the LAI and Canopy-open. We classified the laser data into 4 classes, that is, First pulse, Last pulse, Only pulse and Ground pulse. We counted the number of the each pulse in the 102 circles those centers were the ground truth points and each diameter was 40m. Here we introduce new indices: the ratio of the Last pulse (LFO) or Ground pulse (GFO) to (First pulse + Only pulse) and vegetation flux (VF). The ratio of the Ground pulse (GFO) and VF had very strong liner correlation to LAI (r = -0.840) and Canopy-open (r = 0.885). We made a multiple regression model for predicting LAI from LFO and GFO, and its adjusted R square was 0.704. Each analysis had a very strong correlation to the LAI estimated from fisheye photos, therefore the estimation of LAI from the laser scanner turned out to be so effective. It remains some problems. The difficulty in estimation of LAI from the laser scanner is getting the Ground pulses. We are only able to estimate the LAI which is lower than 2.360 from the regression model obtained because the constant of the equation is 2.369. Hereafter it will be the subject how to estimate the LAI over 2.360.