Development of Mathematical Models for the Estimation of Dendrometric Variables Based on Unmanned Aerial Vehicle Optical Data: A Romanian Case Study

Research highlights: In this study, the possibility of developing predictive models for both individual trees and forest stands, based on information derived from digital surface (DSMs), was evaluated. Background objectives: Unmanned aerial systems (UASs) make it possible to obtain images with increased spectral spatial resolution at a lower cost. Based variables extracted by means representation surfaces, we aimed generating mathematical that would allow prediction main biometric features stands. Materials methods: Forest stands are characterized various structures. As such, measurements may address upper-level trees, but most often oriented towards those belonging mean tree category, randomly selected identifiable models. case grouped is best practice measure projected area entire canopy. Tree stand volumes can be determined using measured in UAS-derived For current 170-year-old mixed sessile oak were examined. Results: Mathematical developed (i.e., crown diameter height) way, obtained results root square error (RMSE) values 18.37% diameter, 10.95% height, 8.70% volume. The simplified process allowed estimates volume or breast producing RMSE 9%. Conclusions: accuracy evaluation depends structural complexity studied plots, quality DSM. turn, leads necessity parametrize used such manner explain variation induced structure.