Subtropical forests are intensive carbon sinks but will suffer more and more frequent drought events in the future. However, model predictions on how subtropical forests respond to persistent drought remain large uncertainty, due to the insufficient knowledge about the mechanisms underlying the drought resistance and resilience of dominant tree species. In this study, we conducted a well-designed common garden experiment by controlling the drought and recover regimes, to explore how five dominant species in a subtropical forest respond to persistent drought events.
Results/Conclusions
Our results showed that withholding water significantly reduced leaf water potential, photosynthesis and transpiration, and lead to the defoliation and death of trees in three to five weeks. Different species exhibited differential morphological and physiological traits. But their relative rank of performance was consistent between drought and recovery periods, by showing that more resistant species recovered more rapidly. However, the drought tolerant traits such as turgor loss point and hydraulic safety margin did not well predict the variation in resistance and resilience among the five species. For example, the two species with the most negative turgor loss points (Neocinnamomum chekiangense and Phoebe chekiangensis) had the lowest resistance and resilience, while other two species with less negative turgor loss points (Castanopsis sclerophylla and Schima superba) had higher resistance and resilience. Interestingly, the water potential at 50% loss of hydraulic conductance in stem was strongly related to both drought resistance and resilience. These results suggested that the differences in drought resistance and resilience among subtropical tree species might be mainly determined by the drought avoidant strategies, rather than drought tolerant ones.