Tracking the temporal dynamics of insect defoliation by high?resolution radar satellite data

Quantifying tree defoliation by insects over large areas is a major challenge in forest management, but it essential ecosystem assessments of disturbance and resistance against herbivory. However, the trajectory from leaf-flush to insect refoliation broadleaf trees highly variable. Its tracking requires high temporal- spatial-resolution data, particularly fragmented forests. In unique replicated field experiment manipulating gypsy moth Lymantria dispar densities mixed-oak forests, we examined utility publicly accessible satellite-borne radar (Sentinel-1) track fine-scale temporal defoliation. The ratio backscatter intensity between two polarizations data growing season constituted canopy development index (CDI) normalized CDI (NCDI), which were validated optical (Sentinel-2) terrestrial laser scanning (TLS) as well intensive caterpillar sampling fogging. NCDI strongly correlated with TLS (Spearman's ? = 0.79 0.84, respectively). significantly explained abundance (R2 0.52). at critical timesteps ?NCDI related discriminated heavily lightly defoliated We demonstrate that spatial resolution cloud independence Sentinel-1 potentially enable spatially unrestricted measurements dynamic This can help monitor pests, improve prediction outbreaks facilitate monitoring disturbance, one priority Essential Biodiversity Variables, near future.