Integration of In Situ and Sentinel-2 Data to Assess Soil Quality in Forest Monitoring: The Case Study of the Vesuvius Fires

The climatic conditions in southern Italy favor the occurrence and spread of forest fires, with severe long-lasting consequences on the local flora and fauna. On the one hand, biological and chemical in situ measurements are typically used to accurately investigate the evolution of the land affected by fires, with limited spatial coverage. On the other hand, Remote Sensing (RS) is a mature technology to complement the in situ campaigns on large regions with adequate revisit time. In this paper, we evaluate the capability of Sentinel-2 data to spatially and temporally extend post-fire in situ analysis on a fire-affected area. In particular, we estimate the soil quality index from Sentinel-2 data and achieve a remarkable coefficient of determination (R2=0.79) and low relative error (er=0.06), highlighting the robustness of the proposed approach. Furthermore, the soil water content and the total iron (Fe) concentrations emerged as pertinent indicators detectable through Near-Infrared and Short-Wave Infrared Sentinel-2 bands. The obtained results prompted an investigation into the post-fire evolution of soil properties, thanks to RS data, in a large area covered by diverse vegetation types. The obtained results encourage a deeper synergic use of in situ and remotely observed data, enabling a comprehensive understanding of soil quality dynamics in fire-affected regions.