Stress legacy effects: early drought and flooding shape subsequent morphophysiological responses in Eugenia uniflora

Drought and flooding events are becoming increasingly frequent and intense due to climate change. We examined how drought and flooding affect the morphophysiological performance of Eugenia uniflora, focusing on gas exchange, water status and growth traits. E. uniflora's responses to water stress are strongly influenced by previous hydrological conditions. Early drought caused marked declines in plant water status, photosynthesis, and water-use efficiency, while early flooding had negligible effects on morphological and physiological traits, reflecting the species' high flood tolerance. Preconditioning through previous flooding or exposure to a single drought mitigated the negative effects of subsequent stress, allowing partial or full recovery of gas exchange and growth traits, with morphological adjustments stabilizing more rapidly than physiological responses. In contrast, recurrent drought imposed severe constraints on water status, gas exchange, and growth, highlighting the cumulative burden of repeated stress, whereas recurrent flooding elicited moderate physiological declines without affecting growth traits. These results demonstrate that both the type and sequence of water stress shape the resilience of E. uniflora, with morphophysiological plasticity and stress history enabling rapid adjustments to fluctuating hydrological conditions in subtropical riverine forests. This resilience suggests that the species could be valuable for restoring riparian ecosystems facing hydrological extremes.