Characterizing Low-Lying Coastal Upland Forests to Predict Future Landward Marsh Expansion

We conducted TLS scanning between July and September 2022 (during leaf-on conditions). For each plot, we performed single-scan positions using a RIEGL VZ-400i (RIEGL Laser Measurement Systems GmbH, Horn, Austria). The VZ-400i operates in the near infrared wavelength (1550 nanometers) with range distances up to 350 meters. The scanner was mounted on a tripod 1.3 meters above the ground and equipped with a tilt mount in order to obtain one upright and one titled scan (90° from the vertical). To create a single point cloud from the two scans, reflector targets were placed around the scanner prior to scanning. The reflectors remain in the exact same positions for both scans, and are used to compute a transformation matrix in the RIEGL RiSCAN Pro software which facilitates the co-registration and merging of the two-point clouds. Alignment of the scans was also further refined using the multi-station adjustment (MSA) module in RiSCAN Pro (Wilkes et al. 2017, Decuyper et al. 2018). The purpose of using the single scan positions from the TLS was to provide an objective representation of forest stand structure at fixed distances from the forest edge and was more time efficient compared to scanning multiple positions within a plot (Calders et al. 2014, Seidel et al. 2016, Meeussen et al. 2020).