Forest Inventory with Personal Laserscanners

The forest inventory provides information and data as a basis for decision-making in forest planning with regard to the implementation of operational interventions and the achievement of economic objectives. In addition to traditional surveying methods, forest inventories with laser scanners have recently become increasingly important. While terrestrial laser scanners (TLS) have been in use for some time, the first experiences and research results on forest inventories with mobile person-carried laser scanners (PLS) have recently become available. In the last six years, automatic algorithms for the evaluation of 3D laser data have been developed at the BOKU Institute of Forest Growth, thus laying the foundation for a modern sensor-based forest inventory. The measurement process with PLS takes about 10 min for a sample circle with 20 m radius. In a series of publications, a large number of reference measurements have shown that tree cover rates of over 97% can be achieved. The mean deviation (bias) of the BHD measurement is 0 - 0.7 cm, with an average error (RMSE) of 1.5 to 3 cm. Tree heights can be automatically determined with a mean deviation of0 to 0.2 m and an average error of 1.5 to 2.1 m. With the portable laser scanner, precise measurement values can now be determined in three-dimensional space in a short time, and the new laser-based forest inventory procedure is thus on the verge of general practical applicability. Together with the Austrian Federal Forests, the new laser-based digital forest inventory procedure is now to be tested in practice on around 300 sample areas in the Ebensee forest district, both in the productive forest and in the protection forest of the Rindbach catchment area. Furthermore, the automatic evaluation routines are to be further developed. In addition to the traditional inventory parameters, the laser scans will be used to automatically and precisely derive indicators of regeneration density, crown closure for the establishment of fir regeneration, and deadwood stocks.