Monitoring the biotic stressors in a Mediterranean Holm oak forest: outcomes of the project SpecFor

Holm oak forests are currently a key element in the ecological and socio-economic sustainability of forest ecosystems in the Mediterranean area, but over the last few decades, extensive dieback and mortality episodes of Quercus ilex L. have been documented after severe drought events. The project “SpecFor” focused on a typical Mediterranean forest ecosystem located along the southern coast of Tuscany (Parco Regionale della Maremma) where severe holm oak declines have recently been reported (Summer 2017). The goal is to develop an accurate and high-throughput framework for detecting forest damage and monitoring forest responses to biotic stresses based on the use of satellite imagery: hyperspectral and optical data. A climatological analysis from 1950 to 2023 has been carried out, involving the analysis of temperature and precipitation variables extracted from the ERA5 Land dataset produced and distributed by ECMWF (Copernicus Climate Service). The climatological analysis allowed us to derive the anomaly time series of temperature and precipitation, both annual and monthly, and the most scientifically used drought index (SPEI—Standardised Precipitation--Evapotranspiration Index). Three plots characterized by low, medium, or high degrees of three decline, were evaluated by phytopatological surveys (visual inspection and fungal identification by culturomic approach), and the ecological role of the fungal communities was investigated using Next-Generation Sequencing metabarcoding. Then, the assessment of forest health and tree growth was correlated with the vegetation index (NDVI) derived from satellite images. By combining advanced remote sensing techniques with traditional field methods and molecular analysis, the project aimed to develop a comprehensive approach to understanding the complex interactions between environmental factors, tree health, and fungal communities in Mediterranean Holm oak forests.