Fungal communities are more responsive than bacterial communities to multi-year drought and rainfall redistribution in Mediterranean soils
Understanding how multi-year extreme drought and changes in rainfall distribution reshape soil microbial communities is critical for predicting ecosystem resilience under climate change. In this study, we present a novel long-term field experiment manipulating both the amount and frequency of rainfall in a Mediterranean shrubland, an approach rarely applied in dryland ecosystems. We investigated the effects of these treatments on soil bacterial and fungal communities, assessing shifts in diversity, functional potential, and microbial network structure. Our results reveal contrasting responses between bacteria and fungi. Bacterial communities exhibited high resistance, maintaining a consistent core of shared genera across treatments, suggesting functional redundancy. In contrast, fungal communities were more sensitive, exhibiting greater taxonomic turnover, more treatment-specific genera, and pronounced changes in network complexity. Functional profiling showed that drought conditions enhanced ureolysis and methanotrophy, whereas wetter conditions favored cellulolysis and chitinolysis key processes in soil carbon cycling. These findings provide new evidence of ecological thresholds in microbial communities under sustained drought pressure and highlight that fungi serve as more responsive indicators of long-term drought and rainfall redistribution. This study contributes novel insights into the reassembly of soil microbial communities under climate stress and underscores the importance of incorporating both taxonomic and functional dimensions in ecosystem monitoring, experiments and modeling.