Objective To analyze the photosynthetic adaptations of Cyclobalanopsis gilva to different habitats, and provide theoretical and data supports for scientific breeding and cultivation.

Method Three natural populations of C. gilva in different habitats were studied. Diurnal changes in photosynthetic parameters of C. gilva under natural condition were measured using LI-6400 portable photosynthesis system. The light response curves were obtained.

Result Under different habitats, net photosynthetic rate(Pn) and transpiration rate(Tr) of C. gilva had similar changing patterns, both reached peak at 10:00 and 14:00, and were lowest at 13:00. Leaf temperature (θ_L), photosynthetically active radiation(PAR), and stomatal conductance(Gs) were all strongly positively correlated with Pn. The ability of using light for C. gilva was influenced by habitat as shown by the light response curves; C. gilva grown on flat between mountains had the best ability of using light, followed by C. gilva grown on southern slope of mountain, and then northern slope of mountain. Light compensation points (Lcp) were low in all three habitats. Lcp was the lowest (2.257 mol·m^-2·s^-1) for C. gilva grown on northern slope of mountain, and around 51 mol·m^-2·s^-1 for C. gilva grown on flat between mountains and southern slope of mountain. Light saturation point (Lsp) was the highest for C. gilva grown on flat between mountains, followed by C. gilva grown on southern slope of mountain, and then northern slope of mountain.

Conclusion C. gilva had strong adaptability to all three habitats. C. gilva grown on flat between mountains and southern slope of mountain have adapted to longer light duration and higher light intensity, and have strong photosynthetic capacity and ability of using hight light intensity. C. gilva grown on southern slope of mountain have the ability of using weak light intensity. Long adaptation to different habitats was the main cause of photosynthetic capacity differences of C. gilva.