Estimating the threshold of detection on tree crown defoliation using vegetation indices from UAS multispectral imagery
Otsu, Kaori (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Pla, Magda (InForest JRU)
Duane Bernedo, Andrea (InForest JRU)
Cardil, Adrián (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Brotons, Lluís (Centre de Recerca Ecològica i d'Aplicacions Forestals)

Data:	2019
Resum:	Periodical outbreaks of Thaumetopoea pityocampa feeding on pine needles may pose a threat to Mediterranean coniferous forests by causing severe tree defoliation, growth reduction, and eventually mortality. To cost-effectively monitor the temporal and spatial damages in pine-oak mixed stands using unmanned aerial systems (UASs) for multispectral imagery, we aimed at developing a simple thresholding classification tool for forest practitioners as an alternative method to complex classifiers such as Random Forest. The UAS flights were performed during winter 2017-2018 over four study areas in Catalonia, northeastern Spain. To detect defoliation and further distinguish pine species, we conducted nested histogram thresholding analyses with four UAS-derived vegetation indices (VIs) and evaluated classification accuracy. The normalized difference vegetation index (NDVI) and NDVI red edge performed the best for detecting defoliation with an overall accuracy of 95% in the total study area. For discriminating pine species, accuracy results of 93-96% were only achievable with green NDVI in the partial study area, where the Random Forest classification combined for defoliation and tree species resulted in 91-93%. Finally, we achieved to estimate the average thresholds of VIs for detecting defoliation over the total area, which may be applicable across similar Mediterranean pine stands for monitoring regional forest health on a large scale.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Unmanned aerial systems (UAS) ; Multispectral imagery ; Forest defoliation ; Thaumetopoea ; Pityocampa ; Vegetation index ; Thresholding analysis
Publicat a:	Drones, Vol. 3 (2019) , p. 1-23, ISSN 2504-446X

DOI: 10.3390/drones3040080

23 p, 6.9 MB

El registre apareix a les col·leccions:
Documents de recerca > Documents dels grups de recerca de la UAB > Centres i grups de recerca (producció científica) > Ciències > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Articles > Articles de recerca
Articles > Articles publicats