Assessing tree dendrometrics in young regenerating plantations using terrestrial laser scanning

Terrestrial laser scanning (TLS) provides a valuable tool for the retrieval of detailed individual-tree structural parameters, but has never previously been applied to young stands under field conditions. The aim was to explore the performance of TLS in a young tree plantation located in a heterogeneous environment in subtropical China. We investigated 438 young trees for congruence between direct field and TLS measurements of total tree height, stem diameter at ground height, and length and height of the longest branch using correlation tests. We applied generalized linear models to examine whether congruence was affected by the observed structural parameter or extrinsic factors (e.g., potential occlusion, point cloud quality). TLS made it possible to detect trees higher than 40 cm. The TLS-retrieved data were highly congruent with the data obtained from direct measurements. The poor descriptions of stems and branches of some individuals of small-sized and leaf-on tree species were due to occlusion by ground vegetation and leaf-on branches. Observed structural parameter and extrinsic factors did not explain the variance between the two approaches. TLS proved to be a promising tool for high-resolution, non-destructive analyses of tree dendrometrics in young regenerating plantations.