An approximately 6-mon prolonged drought occurs yearly in the Hengchun Peninsula of southern Taiwan. Species capable of establishing themselves in this drought environment should be tolerant to drought either through dehydration postponement or dehydration tolerance. To explore drought adaptations of tree species, we investigated predawn leaf water potentials (PWPs) and values of the net photosynthetic rate (Pn) of 9 native tree species which were established in a secondary forest on the west coast of the Hengchun Peninsula. Results showed that both the PWP and Pn in each species significantly declined during the dry season. The PWP during the dry season was maintained at > -0.9 MPa in Pittosporum pentandrum, > -1.5 MPa in Planchonella obovata,Gelonium aequoreum, and Melanolepis multiglandulosa, but < -3.0 MPa in Aglaia formosana. The Pn during the dry season was maintained at > 70% of the level during the rainy season in Hibiscus tiliaceus and Pit. pentandrum, while they were < 50% in Pla. obovata, Gel. aequoreum, and Agl. formosana. A regression analysis was applied to estimate the PWP value of each species when the Pn decreased to 0. It was found that PWP values of Hib. tiliaceus, Allophylus timorensis, and Agl. formosana, were as low as -7.24, -4.57, and -4.40 MPa, respectively, indicating that these 3 species possess high physiological tolerance abilities against drought through dehydration tolerance.During the dry season, few leaves were retained on saplings of Broussonetia papyrifera,All. timorensis, Mel. multiglandulosa, and Ehretia resinosa. These species adopted a dehydrationpostponement mechanism by shedding most of their leaves. Pittosporum pentandrum, Pla. obovata, and Gel. aequoreum, 3 evergreen species, on the other hand, had extended root systems to enhance soil water absorption, which is also a dehydration-postponement mechanism. The 2 mechanisms are not mutually exclusive, and each species could incorporate various approaches for drought tolerance. Hibiscus tiliaceus might also have extended root systems in addition to adopting a dehydration-tolerance mechanism. Planchonella obovata, Bro. papyrifera, All. timorensis, and Ehr. resinosa also possessed physiological tolerance abilities in addition to adopting a dehydrationpostponement mechanism.