Effects of Forest Growth on Laser Derived Canopy Metrics

In the current research, we present the results from a growth detection study in young forest and mature pine-dominated forest located on poor sites. Canopy height distributions were created from small-footprint airborne laser scanner data collected over 87 georeferenced field sample plots. The size of each plot was 300-400 m. The laser data were acquired in 1999 and 2001, and none of the plots had been subject to any harvests or serious natural disturbances in the period between the two laser data acquisitions. Canopy height distributions were created from first pulse data. Height percentiles (10%, 50% and 90%), mean and maximum height values, and canopy density at three different height intervals above the ground were computed from the laser-derived canopy height distributions. Corresponding metrics derived from the laser data acquired in 1999 and 2001 were compared. All metrics derived from the first pulse data differed significantly between data acquired in 1999 and 2001 in the young forest and seven of eight metrics differed significantly in the mature forest. The mean values for the difference in mean height and maximum height were 1.24 and 1.11 m in young and 0.43 and 0.22 m mature forest, respectively.