Mediterranean ecosystems are increasingly exposed to climate-induced shifts in rainfall patterns, including reduced total precipitation and altered event frequency. These changes may impact the performance and survival of key perennial species. Here, we tested the interactive effects of multi-year extreme drought and rainfall distribution on the growth and physiology of two geophytes (Asphodelus ramosus, Cyclamen persicum) and two shrubs (Pistacia lentiscus, Salvia fruticosa) at the Matta Long-Term Ecological Research site in the Judean Hills, Israel. Over five years, we applied a 66% reduction in annual precipitation using rainout shelters, with treatments simulating either low- or high-frequency irrigation pulses (three vs. nine rainfall events per season), alongside a drought treatment with natural rainfall variability and a control.
In the extreme drought year of 2025, geophytes exhibited greater physiological sensitivity to drought compared to shrubs. A. ramosus showed legacy effects from previous drought years, while C. persicum responded primarily to current conditions. Shrubs maintained more stable physiological performance, likely due to deeper rooting or broader hydraulic plasticity. Across species, plants in high-frequency rainfall plots outperformed those in low-frequency treatments, emphasizing the role of rainfall timing in mitigating drought stress.
This study provides rare multi-year experimental evidence on how rainfall frequency and drought severity interactively influence Mediterranean perennials. The findings highlight species-specific vulnerabilities and suggest that rainfall distribution, not just total precipitation, is critical in predicting plant resilience to climate extremes.
