Sentinel-2 based prediction of spruce budworm defoliation using red-edge spectral vegetation indices

ABSTRACT

This research compares the capabilities of various Sentinel-2-derived spectral vegetation indices (SVIs) in particular red-edge SVIs to detect and classify spruce budworm (Choristoneura fumiferana) (SBW) defoliation using Support Vector Machine (SVM) and Random Forest (RF) models. The results showed the superiority of RF in model building for defoliation detection and classification into three classes (nil, light, and moderate) with overall errors of 17% and 32%, respectively. The most important variables for the best model were Enhanced Vegetation Index 7 (EVI7), Modified Chlorophyll Absorption in Reflectance Index (MCARI), Inverted Red-Edge Chlorophyll Index (IRECI), Normalized Difference Infrared Index 11 (NDII11) and Modified Simple Ratio (MSR). Red-edge SVIs were more effective variables for light defoliation detection compared to traditional SVIs such as Normalized Difference Vegetation Index (NDVI) and EVI8. These findings can help improve current remote sensing-based SBW defoliation detection and monitoring.

Acknowledgments

The authors would like to thank New Brunswick Department of Energy and Resource Development for providing defoliation field data for this project.

Declaration of interest statement

The authors declare no conflicts of interest.

Additional information

Funding

This work was supported by the USDA National Institute of Food and Agriculture, McIntire-Stennis Project # ME042003 and National Aeronautics and Space Administration (NASA) Cooperative Agreement awarded through the Maine Space Grant Consortium [80NSSC19M0155].