Assessing forest stand attributes by laser scanner

The stem volume, basal area And mean height of Norway spruce and Scots pine stands and individual trees were derived using canopy height metrics by means of a laser scanner TopoSys-1. Due to the high pulse rate of the laser scanner, individual tree statistics could be obtained. Methods to generate DTM and tree crown map from laser data were reported. Stand-wise and tree-wise field inventory data was regressed against laser-derived features. The coefficients of determination were in the range between 0.84 and 0.88 for the stem volume, basal area and mean height. The obtained accuracy was equivalent to conventional stand-wise forest inventory implying that the described approach can be used operationally. Further, it was shown that the tree height estimation accuracy of single and dominant trees was 1.5 m using the laser scanner. The accuracy of conventional clinometer measurements is typically better than 0.5 m but the time spent for height measurements is enormous. With the laser, the height of all dominant trees could be assessed within a fraction of time.