Fig 5: Example of AOP LiDAR point cloud (upper) within the delineated boundary (lower embedded photo) of a tuliptree at ORNL, TN, and its unfiltered vertical profiles of LiDAR intensity, plant area density (PAD) and PAR (lower)
● We quantify several traits for 197 crowns delineated by NEON terrestrial team, including plant/leaf area index (PAI/LAI), max canopy height (MAXCH), mean outer canopy height (MOCH), accumulative plant area density (APAD), accumulative LiDAR intensity (AInt), etc.
● We voxelize (1m) LiDAR point cloud and compute traits using established methods and open R packages, e.g., lidR (Roussel e al., 2020); leafR (de Almeida et al., 2019); canopyLazR (Kamoske et al., 2019).
● Data quality check:
1. Invalid crowns are excluded by checking each delineation (Fig 5 lower embedded 0.1m-resolution photo).
2. We use vertical profiles of photosynthetically active radiation (PAR) to cut off understory noises by setting lower height threshold where tangent line of PAR starts to approach vertical (Fig 5 lower).
3. LiDAR intensity should attenuate by height (Fig 5).
3.2. MLA