Forest Harvest Detection Using SAR Coherence Time Series: A Case Study of Bark Beetle Outbreak in the Czech Republic

Climate change-induced forest disturbances present a growing concern in European forests, making effective monitoring crucial. While optical remote sensing can provide important insights into these dynamics, there are limitations that underscore the utility of Synthetic Aperture Radar (SAR) data. We generated time series of SAR coherence images to examine the coherence trends in forests affected by bark beetle outbreak in the Czech Republic (Central Europe), followed by the salvage removal of killed trees. We compared these trends with the ground truth data indicating forest harvest locations on an annual basis. Our results indicate an increasing coherence trend, interspersed with seasonal variations, during the outbreak period. Visually, a significant agreement was observed between high coherence areas and the harvest data, as well as when compared with optical data. Future research should aim to better understand the utility of SAR coherence data for forest disturbance mapping, especially if new Sentinel 1 C-band satellites are slated for launch.