RT Journal Article T1 Characterization of Shrub Fuel Structure and Spatial Distribution Using Multispectral and 3D Multitemporal UAV Data A1 Díaz Varela, Ramón Alberto A1 Alonso Rego, Cecilia A1 Arellano Pérez, Stéfano A1 Briones Herrera, Carlos Iván A1 Álvarez González, Juan Gabriel A1 Ruiz González, Ana Daría K1 Shrubland K1 Object-based vs. pixel-based classification K1 Vegetation classification K1 Fuel models classification K1 Unmanned aerial vehicles K1 3D point cloud K1 Multispectral imagery K1 Plant height AB Shrubland vegetation plays a crucial role in ecological processes, but its conservation is facing threats due to climate change, wildfires, and human activities. Unmanned Aerial Vehicles (UAVs), or ‘drones’, have become valuable tools for detailed vegetation mapping, providing high-resolution imagery and 3D models despite challenges such as legal restrictions and limited coverage. We developed a methodology for estimating vegetation height, map vegetation classes, and fuel models by using multitemporal UAV data (imagery and point clouds from the imagery) and other ancillary data to provide insights into habitat condition and fuel characteristics. Two different random forest classification methods (an object- and a pixel-based approach) for discriminating between vegetation classes and fuel models were developed and compared. The method showed promise for characterizing vegetation structure (shrub height), with an RMSE of less than 0.3 m and slight overestimation of taller heights. For discriminating between vegetation classes and fuel models, the best results were obtained with the object-based random forest approach, with overall accuracies of 0.96 and 0.93, respectively. Although some difficulties were encountered in distinguishing low shrubs and brackens and in distinguishing low-height fuel models due to the spatial mixture, accurate results were obtained for most classes. Future improvements include refining terrain models by including data acquired with UAV aerial scanners and exploring different phenological stages and machine learning approaches for classification. PB MDPI YR 2025 FD 2025-04-12 LK https://hdl.handle.net/10347/42594 UL https://hdl.handle.net/10347/42594 LA eng NO Díaz-Varela, R.A., Alonso-Rego, C., Arellano-Pérez, S., Briones-Herrera, C.I., Álvarez-González, J.G., & Ruiz-González, A.D. (2025) Characterization of Shrub Fuel Structure and Spatial Distribution Using Multispectral and 3D Multitemporal UAV Data. "Forests", 16, pp. 1-23. https://doi.org/ 10.3390/f16040676 NO This work was supported by the project: INIA-RTA2017-00042-C05 (VIS4FIRE) funded by the Spanish National Program of Research, Development and Innovation (Plan Estatal de I + D + i) co-financed by the European Regional Development Fund (ERDF) of the European Union. DS Minerva RD 23 abr 2026