Revealing changes in the stem form and volume allocation in diverse boreal forests using two-date terrestrial laser scanning

Funding Information: This research was funded with a grant by the Finnish Cultural Foundation as well as by the Academy of Finland, grant numbers 315079, 345166, 331711, 334001, 337810, and 337127. Acknowledgments: The authors would like to thank Häme University of Applied Sciences for supporting the research activities in Evo. Open access funding provided by University of Helsinki. Conflicts of Interest: The authors declare no conflict of interest. Funding Information: Funding: This research was funded with a grant by the Finnish Cultural Foundation as well as by the Academy of Finland, grant numbers 315079, 345166, 331711, 334001, 337810, and 337127. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Tree growth is a multidimensional process that is affected by several factors. There is a continuous demand for improved information on tree growth and the ecological traits controlling it. This study aims at providing new approaches to improve ecological understanding of tree growth by the means of terrestrial laser scanning (TLS). Changes in tree stem form and stem volume allocation were investigated during a five-year monitoring period. In total, a selection of attributes from 736 trees from 37 sample plots representing different forest structures were extracted from taper curves derived from two-date TLS point clouds. The results of this study showed the capability of point cloud-based methods in detecting changes in the stem form and volume allocation. In addition, the results showed a significant difference between different forest structures in how relative stem volume and logwood volume increased during the monitoring period. Along with contributing to providing more accurate information for monitoring purposes in general, the findings of this study showed the ability and many possibilities of point cloud-based method to characterize changes in living organisms in particular, which further promote the feasibility of using point clouds as an observation method also in ecological studies.Peer reviewe