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Airborne Laser Scanning of Forest Stem Volume in a Mountainous Environment
Christian Doppler Laboratory for “Spatial Data from Laser Scanning and Remote Sensing”, at the Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, Gußhausstraße 27-29, 1040 Vienna, Austria
Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, Gußhausstraße 27-29, 1040 Vienna, Austria
Stand Montafon Forstfonds, Montafonerstraße 21, 6780 Schruns, Austria
Department of Forest Inventory at the Federal Research and Training Center for Forests, Natural Hazards and Landscape, Seckendorff-Gudent-Weg, 1130 Vienna, Austria
* Author to whom correspondence should be addressed.
Received: 20 July 2007; Accepted: 14 August 2007 / Published: 17 August 2007
Abstract: Airborne laser scanning (ALS) is an active remote sensing technique that uses the time-of-flight measurement principle to capture the three-dimensional structure of the earth’s surface with pulsed lasers that transmit nanosecond-long laser pulses with a high pulse repetition frequency. Over forested areas most of the laser pulses are reflected by the leaves and branches of the trees, but a certain fraction of the laser pulses reaches the forest floor through small gaps in the canopy. Thus it is possible to reconstruct both the three-dimensional structure of the forest canopy and the terrain surface. For the retrieval of quantitative forest parameters such as stem volume or biomass it is necessary to use models that combine ALS with inventory data. One approach is to use multiplicative regression models that are trained with local inventory data. This method has been widely applied over boreal forest regions, but so far little experience exists with applying this method for mapping alpine forest. In this study the transferability of this approach to a 128 km2 large mountainous region in Vorarlberg, Austria, was evaluated. For the calibration of the model, inventory data as operationally collected by Austrian foresters were used. Despite these inventory data are based on variable sample plot sizes, they could be used for mapping stem volume for the entire alpine study area. The coefficient of determination R2 was 0.85 and the root mean square error (RMSE) 90.9 m3ha-1 (relative error of 21.4%) which is comparable to results of ALS studies conducted over topographically less complex environments. Due to the increasing availability, ALS data could become an operational part of Austrian’s forest inventories.
Keywords: Keywords: LiDAR; DTM; canopy height; forest inventory; stem volume.
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MDPI and ACS Style
Hollaus, M.; Wagner, W.; Maier, B.; Schadauer, K. Airborne Laser Scanning of Forest Stem Volume in a Mountainous Environment. Sensors 2007, 7, 1559-1577.
Hollaus M, Wagner W, Maier B, Schadauer K. Airborne Laser Scanning of Forest Stem Volume in a Mountainous Environment. Sensors. 2007; 7(8):1559-1577.
Hollaus, Markus; Wagner, Wolfgang; Maier, Bernhard; Schadauer, Klemens. 2007. "Airborne Laser Scanning of Forest Stem Volume in a Mountainous Environment." Sensors 7, no. 8: 1559-1577.