Climate change and ecological vulnerability of Mediterranean coastal wetlands: Native soil microbiome as Nature-based Solutions in plant community resilience

This thesis investigates the effects of climate change on the ecological vulnerability of wetlands, with a particular focus on Mediterranean coastal systems. The aim is to provide a deeper understanding of the mechanisms through which climate-driven abiotic stressors, especially salinity, influence wetland functioning, plant establishment, and ecosystem resilience. By analysing both large-scale ecological patterns and species-specific responses during early plant development, this thesis contributes to the identification of critical vulnerability points and explores innovative Nature-based Solutions (NbS) capable of supporting restoration under future climate scenarios. For this purpose, the research combines a systematic review of climate-change impacts on Mediterranean coastal wetlands with experimental studies on microbial biopriming using native biocrust microbiota. This integrated framework allows linking macro-scale environmental pressures with micro-scale physiological processes involved in seed germination and early seedling growth, two life stages recognized as particularly sensitive to salinity. Special attention is given to the role of biocrust-derived cyanobacteria and plant growth-promoting bacteria (PGPB), evaluating their potential to modulate plant performance under salt stress and to act as sustainable, low-impact tools for ecological restoration in degraded or salinizing wetlands.