This study investigates the decline of Mediterranean stone pine forests caused by climate stress and insect outbreaks, focusing on Castelporziano Estate in Italy. It proposes a multi-source remote sensing approach combining high-resolution (Pléiades, DigitalGlobe), Sentinel-2, and PlanetScope data to detect and monitor disturbances. Sentinel-2 enables near-real-time yearly mapping using an improved unsupervised algorithm, while PlanetScope reveals an average detection delay of 8.5 days. The method achieves high accuracy (85–92%) when validated against detailed imagery. Overall, integrating multiple data sources improves the timeliness and reliability of monitoring, supporting effective management of forests increasingly threatened by climate change and insect infestations.