Analyzing forest canopies with ground-based laser scanning: A comparison with hemispherical photography

We tested ground-based high resolution laser scanning as a tool for analyzing the complex canopy structure of temperate broad-leaved forests. The canopies of 35 groups of trees were analyzed by laser scans from various positions inside a mixed stand to generate three-dimensional (3D) point clouds of the axes and leaves. The scan data was used to produce hemispheric views of the canopy at various locations that were compared to synchronously taken hemispherical photographs of the same part of the canopy. We conclude that terrestrial laser scanning (TLS) in mature forests can overcome several of the methodological problems inherent to conventional canopy analysis with optical methods and thus may soon offer a promising tool for functional research in complex forest canopies. Certain limitations of the TLS approach, mostly caused by hardware limitations that will probably soon be overcome, are encountered.