Unveiling short-term variability in post-fire recovery of Mediterranean vegetation with Sentinel-2 time series analysis

Forest fires are a frequent disturbance in the Mediterranean Basin, and native vegetation has evolved adaptations to them. However, climate-driven changes in fire regime increase the need to monitor post-fire recovery, especially under large, high-severity events, shifts in climate, and repeated burning. Post-fire vegetation dynamics using Sentinel-2 Normalized Burn Ratio (NBR) time series were analyzed in four common Mediterranean forest and shrubland types (~4500 ha burned in six 2017 summer wildfires in Sicily). Using TIMESAT, phenology metrics were extracted from NBR and recovery for up to 76 months (Aug 2017-Dec 2023) post-fire was tracked. High-resolution Google Earth imagery supported physiognomic classification, while Random Forest models assessed the influence of burn severity, climate, reburning, and topography. Mediterranean maquis showed the fastest recovery, reaching pre-fire NBR values within 4, 6, and 8 months under low, moderate, and high severity, respectively. By contrast, conifer reforestations recovered poorly, rarely returning to pre-fire levels even at low severity, a pattern confirmed by analysis of Google Earth imagery. Results from Random Forest models highlighted pre-fire conditions among the top predictors for all vegetation types. Fire severity strongly influenced Quercus ilex forests and maquis, whereas climate variables were more significant for Eucalyptus spp. plantations and conifers. Reburning and topography were less influential. Overall, Mediterranean maquis was the most resilient, while conifer reforestations were the least. These findings stress the importance of monitoring systems to guide land management, identify areas with poor recovery, and detect ongoing ecosystem degradation. • Open-access, multi-source approach was used to investigate post-fire phenology. • Random Forest models were used to assess influence of several factors on recovery. • Mediterranean maquis showed the fastest recovery, conifers the poorest. • Pre-fire conditions, fire severity and climate influenced recovery the most. • Reburning and topography were less influential on short-term recovery.