Guerra Hernández, JuanGonzález Ferreiro, EduardoMonleón, VicenteFaias, SoniaTomé, MargaridaDíaz Varela, Ramón Alberto2018-10-232018-10-232017Guerra-Hernández, J., González-Ferreiro, E., Monleón, V. J., Faias, S. P., Tomé, M., & Díaz-Varela, R. A. (2017). Use of Multi-temporal UAV-derived imagery for estimating individual tree growth in Pinus pinea stands. Forests, 8(8), 3001999-4907http://hdl.handle.net/10347/17618High spatial resolution imagery provided by unmanned aerial vehicles (UAVs) can yield accurate and efficient estimation of tree dimensions and canopy structural variables at the local scale. We flew a low-cost, lightweight UAV over an experimental Pinus pinea L. plantation (290 trees distributed over 16 ha with different fertirrigation treatments) to determine the tree positions and to estimate individual tree height (h), diameter (d), biomass (wa), as well as changes in these variables between 2015 and 2017. We used Structure from Motion (SfM) and 3D point cloud filtering techniques to generate the canopy height model and object-based image analysis to delineate individual tree crowns (ITC). ITC results were validated using accurate field measurements over a subsample of 50 trees. Comparison between SfM-derived and field-measured h yielded an R2 value of 0.96. Regressions using SfM-derived variables as explanatory variables described 79% and 86–87% of the variability in d and wa, respectively. The height and biomass growth estimates across the entire study area for the period 2015–2017 were 0.45 m ± 0.12 m and 198.7 ± 93.9 kg, respectively. Significant differences (t-test) in height and biomass were observed at the end of the study period. The findings indicate that the proposed method could be used to derive individual-tree variables and to detect spatio-temporal changes, highlighting the potential role of UAV-derived imagery as a forest management tooleng© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)http://creativecommons.org/licenses/by-nc-sa/4.0/Unmanned aerial vehicles (UAV)Forest inventoryBiomass growthCanopy heigh model (CHM)Object based image analysis (OBIA)Structure from Motion (SfM)Materias::Investigación::31 Ciencias agrarias::3106 Ciencia forestal::310608 Silviculturajournal article10.3390/f8080300open access