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06.05.2015 10:58

SF Einstein, 7. May, 21.00 hrs: Terrestrial Laser Scanning of the Forest Architecture in the Masoala Hall (Zürich)

Swiss TV accompanied UZH-Geographer Felix Morsdorf on testing his 3D scanner in the Masoala hall of the Zurich Zoo. Morsdorf's goal is to make sure that his instruments will support the heat and humidity they are going to be exposed in Borneo.

Illustration of 3D point data of a temperate mixed forest in Switzerland measured using airborne (ALS) and terrestrial laser scanning (TLS). The TLS data is of very high spatial resolution, which enables to describe the canopy architecture in detail. However, when measuring from the ground only, the uppermost parts of the canopy cannot be sampled due to occlusion. In a dense forest it is therefore needed to measure from multiple vertical positions within the canopy (e.g., using a canopy crane) and/or to combine the data with air- borne measurements

The three-dimensional structural complexity of the forest architecture is of main importance in studying forest ecosystem functioning. Forest architecture is driving light availability and influencing resource management and species diversity. Structural complexity is known to enhance resource-use efficiency, ecosystem productivity, and biodiversity of forest ecosystems. Complex and stratified forest canopies, as for instance found in tropical rain forests, offer resource-rich habitats for tree and nontree species. Hence, the  interest in forest structure in the context of the UZH URPP "Global Change and Biodiversity".

To describe and quantify the forest architecture, plant area index (PAI) has been identified as a key functional trait, which is linked to the structural complexity (spatial distribution of plant material) and the biomass (size and density of leaves and wood) of forest canopies. Over the last decades, it has typically been measured in 2D as vertically integrated value (unit m2m2). Only recent advances in light detection and ranging (LiDAR) enabled to derive PAI in 3D space, also known as plant area density (PAD, unit m2m3). This opens unprecedented opportunities for detailed forest reconstruction and 3D modeling of the canopy architecture. Especially terrestrial laser scanning (TLS) is an emerging technique increasingly being used in forests, since it provides very high spatial resolution (resolving single leaves).

Felix Morsdorf from the Schaepman group and his team plan to do TLS measurements in the Lambir Hills National Park from the ground and from the canopy crane. TLS measurements are non-destructive remote sensing measurements, which are based on the LiDAR measurement principle. To test the instrument in humid conditions and to improve the workflow, Morsdorf made a survey of the Masoala hall in Zurich Zoo in mid March. The derived 3D information will then be provided to the Zoo for visualization purposes. In addition, some of the methods will be tested on that data, as the vegetation in the Masoala hall is very well documented. 

Swiss TV accompanied this test phase and will broadcast it in the course of Einstein on May 7th at 21.00 hrs. 

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