Abstract:Plant hydraulic traits can reflect the adaptability of plants to different water conditions. It is important to study the hydraulic traits of dominant plants in the special habitat of tropical coral islands for a deep understanding of the hydraulic adaptation strategies of tropical coral island plants, and for selecting suitable tree species for tropical coral island vegetation construction and restoration. Thus, the leaf and branch hydraulic traits of two representative dominant tree species in the habitat of tropical coral islands of China, i.e., Pisonia grandis and Scaevola sericea, were measured, and their hydraulic adaptation strategies were compared and analyzed. The results showed that the leaf embolism resistance, leaf turgor point and branch specific xylem conductivity of P. grandis were significantly higher than those of S. sericea, but the values of branch embolism resistance, leaf hydraulic conductance, sapwood density and leaf to stem area ratio were significantly lower than those of S. sericea. Furthermore, leaves of P. grandis were more resistant to embolism than branches, and were sensitive to water stress. Meanwhile, high water transport efficiency in branches of P. grandis provided sufficient water to ensure the high transpiration of the leaves. On the other hand, there was a significant hydraulic vulnerability segmentation between leaves and branches of S. sericea. The leaves of S. sericea could act as “safety valves” to protect branch hydraulic pathway from dysfunction. Pisonia grandis and S. sericea could adapt to the special habitats of tropical coral islands by coordinating the water transport efficiency and safety of leaves and branches and adopting different hydraulic strategies.