Ecology Responses Of Typical Seedlings In Subtropical Regions Under Acid Rain Or UV-B Radiation Stress

UV-B radiation and acid rain are the global environmental problems. The studies of them mostly were on the aspects of growth, photosynthetic physiology, and water physiology and so on; fewer were on the aspects of exploring the physiology response to the plants under environmental stress from the views of community succession and restoring degenerate forest.As the research material, the test selected the dominant plant species in different succession stages in the evergreen broad-leaved forest. The author tries to explore the effects of normal succession of evergreen broad-leaved forest under the environmental stress, through studying the responses of the sample plants to the environmental stress, aims to laying a foundation for restoring degenerate evergreen broad-leaved forest and maintaining community stability in subtropical regions. The results showed that:The supplementary UV-B radiation promoted the growth of S.superba and E.glabripetalus seedlings, and inhibited the growth of C.camphora, C. sclerophylla and L.glaber seedlings; the exclusive UV-B radiation promoted the growth of C.camphora, C. sclerophylla and L.glaber seedlings.The supplementary UV-B radiation reduced the chlorophyll content of L.glaber and E.glabripetalus seedlings, and the effects of it on S.superba, C.camphora and C. sclerophylla seedlings were not significant; the exclusive UV-B radiation increased the chlorophyll content of the seedlings.The supplementary UV-B radiation reduced the photosynthetic physiological parameters values of L.glaber and E.glabripetalus seedlings; it forced the stoma of E.glabripetalus seedling been closed, and increased the WUE of them; the effects of it on water physiology of L.glaber seedling were small. There were some inhibition from the supplementary UV-B radiation to photosynthetic and water using capacity of S.superba, C.camphora and C. sclerophylla seedlings. Except for L.glaber seedling, the exclusive UV-B radiation increased the photosynthetic physiological parameters values of the plants; and different species had different water physiological parameters values under the exclusive UV-B radiation condition.The growth of E.glabripetalus seedling was promoted by the increased acid rain intensity. The growth of S.superba, C.camphora and C. sclerophylla seedlings were inhibited under the acid rain of high intensity, and were promoted under the acid rain of low intensity. The acid rain of different intensity all inhibited the growth of L.glaber seedling.The chlorophyll content, photosynthetic physiological parameters values, Gs and Tr of E.glabripetalus seedling was increased with the increased acid rain intensity, while the WUE was decreased. Under the high intensity acid rain, the photosynthetic capacity of S.superba, C.camphora, C. sclerophylla and L.glaber seedlings were inhibited, the stoma was closed, and WUE was increased. The effects of the low intensity acid rain on photosynthetic and water physiology of S.superba and C.camphora seedlings were not significant, and the physiological parameters values of C. sclerophylla and L.glaber seedlings were decreased a little.The dominant plant species with the same succession stages have the similar physiology response rules under the acid rain and UV-B radiation stress. The same broad-leaved species have the similar rules of physiology response in different environmental stress.