Terrestrial Laser Scanning to help assess forest biodiversity and ecosystem functioning

(17-09-2021) This summer, a team led by Kim Calders and Mengxi Wang of CAVELab collaborated with researchers from FornaLab in the FORBIO experiment.

More than 10 years ago, a forestry experiment was set-up to assess the effects of tree species diversity on FORest BIOdiversity and ecosystem functioning. The so-called FORBIO trial was established at three Belgian sites with contrasting soil and weather conditions (Gedinne, Zedelgem, and Hechtel-Eksel). The design of the experiment follows a classical synthetic community approach, using a fixed species pool of 5 tree species in each plantation (Fig. 1). Plots are planted with 1-4 tree species from a site-specific pool of 5 broadleaved and coniferous tree species. More detail about the experimental design can be found on the FORBIO website.

Ecosystem functioning has been closely monitored since shortly after planting. For the first time, thanks to a successful collaboration with CAVELab, forest structural diversity can now be included as an integral component of the FORBIO assessments. This summer, a team led by Mengxi Wang and Kim Calders completed Terrestrial Laser Scanning (TLS) of all 126 plots across the three FORBIO sites.

Forest structural diversity is strongly linked to forest biodiversity. In order to monitor the effect of species composition on forest structural diversity, we carried out a series of TLS scans using our RIEGL VZ-400 (see photo above of CAVElabber Kasper Coppieters with the LiDAR scanner). Single scans were repeated at four positions in all 126 plots in leaf out condition (Fig.2). With 3D laser scanning, objects near the instrument (up to hundreds of meters) are scanned (Fig.3). Vertical plant profiles are then extracted to accurately delineate the 3D structure of each plot. At FORBIO sites, the differing site condition and other environmental factors can also be considered.

We hope to rescan all plots in the winter in leaf off condition to increase our understanding of the structural composition of the sites, and to continue monitoring all sites in the long run.

Fig.1 Map of Belgium with location of the tree FORBIO plantations

Fig.2 TLS single scans at a FORBIO site

Fig.3 The overview figure of a scan at a FORBIO site