Study On Population And Reproductive Characteristic Of Ceriops Tagal At Different Tidal Zones In Dongzhaigang Of Hainan Province

The distribution patterns of mangrove species under tidal flats are their overall performance, include submergence tolerance, salt tolerance and response to the environment. The C. tagal communities under different tidal zones in Tashi Dongzhaigang of Hainan province were conducted, aimed to understand the impact of different tidal elevation on it. Explore the differences of the population characteristics, cones, hypocotyl morphology, seedling grow, seedling survival and physiological responses of Ceriops tagal under the different tidal zones. And through field and indoor experiments to reveal the factors that affect the distribution of Ceriops tagal. The results of this study can provide a theoretical basis for regeneration of Ceriops tagal. The findings of this study are as follows:(1)On the community and population characteristics, compared with the middle and external tidal community canopy density, the inner tidal community canopy density and the proportion of Ceriops tagal are lower. On the population characteristics of Ceriops tagal,?C. tagal population among different tidal belt are essentially stable stocks or steady-growth populations, but the density disparity significantly;?The diameter and crown structure of C. tagal was no significant change, but the height is different significantly;?For the spatial patterns of population, external tide of C. tagal is random while middle tide and inner tide of C.tagal showed clump;?In the dynamics of spatial patterns of C. tagal population:clump for seedlings and random for both saplings and mature trees in external tide, while both seedlings and saplings are clump and adult trees are random between middle tide and inner tide.(2)On the phonological phase, cones, hypocotyl morphology and regeneration seedlings of C. tagal.?From inner tidal to external tidal C. tagal population, the phonological phase of Ceriops tagal was basically the same, but the cones were decreased, the length, fresh weight and germination rates of hypocotyl were increased;?rom inner tide to external tide, New seedlings decreased and Seedling mortality.(3)Field germination experiments have shown that the germination rate up to100%when flooding time were11.57h per day (from the tidal creeks within15m), but the seedlings after germination almost all died within two months. It is prolonged flooding that cause seedlings death? It needs experimental validation.(4)On the physiological side, from inner to external tidal, physiological response of C. Tagal in different ages is different:?In seedlings, superoxide dismutase(SOD), peroxidase(POD), activity and proline(Pro) content were gradually increased substantially;?n saplings and adult trees, POD activity and Pro were decreased, while SOD. activity was basically upward trend.(5)Indoor germination validation tests are shown as flows:?Hypocotyl germination test under simulated tide-inundated times showed that the germination rate were100%when flooding time were16h per day. This result is in agreement with the results of field germination experiments.?hile, seedlings which hypocotyl germination after two months were no death and their roots were no black. This results are inconsistent with frield germination experiments results. It explains that tidal watterlogging is not the direct cause of death of seedling when flooding time were11.57h per day.?ight-salinity plays remarkable effect to hypocotyl germination of C. tagal Hypocotyl germination and growth are minor difference between shade and no shade when salinity is10%o. When salinity is20%o and3O‰, the hypocotyl germination is100%which it grows under shaded condition, while the hypocotyl germination rate under90%and the roots changed black which it grows under no shaded condition.?ypocotyls are dormancy when the temperature between15?to20?; Hypocotyls are germination when the temperature is between25?to35?; the higher the temperature, the sooner the seed germination; Hypocotyl were wilting and changed black, When the temperature is up to40?.Comprehensive Test results showed that the environment in different tidal zones affact population distribution pattern and update of the Ceriops tagal; The main effect may be the interaction of light-salinity, or a combination of factors. So, in the restoration of Ceriops tagal, it should be noted of shade, planting density and soil salinity conditions. In addition, Ceriops tagal itself can increase the the chlorophyll content or enzymatic activity to resist adversity.