Potential of terrestrial laser scanning for characterizing forest regeneration: A review and an experimental case study.

Forest regeneration monitoring is essential for evaluating ecosystem recovery and informing sustainable forest management. Optical remote sensing methods such as NDVI and EVI are commonly used for this purpose, but they often fail to capture fine-scale structural information, particularly in early successional stages. Terrestrial Laser Scanning (TLS), in contrast, offers high-resolution, three-dimensional data capable of directly detecting tree structure, height distribution, and leaf area index (LAI). This study combines a systematic literature review with original TLS data collected from a regenerating forest plot affected by windstorm disturbance, where multispectral imagery was also acquired. The review highlights the advantages of TLS over optical techniques, particularly in detecting understory vegetation and capturing structural complexity. The experimental results support these findings: TLS enabled the accurate detection of tree saplings that were not visible in optical imagery and allowed for the extraction of height distributions and LAI. These results demonstrate that even single TLS acquisition can provide critical structural insights into forest regeneration that optical methods alone cannot deliver. We conclude that TLS is a valuable tool for monitoring post-disturbance recovery and advocates for its integration with optical remote sensing approaches such as NDVI and EVI to achieve a more comprehensive assessment of forest regeneration.