| Quanzhou Bay estuary wetland is characterized with extensive, biodiversity eco-system typicality and vulnerability determined by its location and unique topographical character. Therefore, it had been regarded as the typical representative of the subtropical estuary wetland. At present, more than 400 hm2 of mangrove plants were planted in Quanzhou Bay estuary wetland in Huian County. However, the mangrove forestation areas is not apparently enough for the Quanzhou Bay estuary wetland nature reserve of 7039.56 hm2 of mangrove area, and the acreage and scale of mangrove forest needs to be expanded. To be continued to planting mangrove plants, it involves in the mangrove tree species selection and reasonable plant allocation. The research objects were the 420 hm2 mangrove plants. The plants'adaptability to environment was analyzed and valued in order to guide to purposeful ecologically restore the wetland in Quanzhou Bay estuary wetland. The appropriate mangrove species selected was planted and allocated in appropriate sites.Three dominant plant species in Quanzhou Bay estuary wetland, Kandelia candel, Aegiceras corniculatum and Avicennia marina, additional two new-introduced plant species, Bruguiera gymnorrioza and Acanthus ilicifolius, three growth indices, such as plant height, diameter, leaf length parameters in different sites and period, were measured, and their diverse growth characteristics were studied. The results showed that Kandelia candel belongs to the rapid growth species, Bruguiera gymnorrioza and Acanthus ilicifolius belong to the medium-rate growth one, Aegiceras corniculatum, Avicennia marina belong to the tardiness one. Mangrove growth was influenced by the surrounding environment. The high salinity and high pH are the main factors that may restrict the growth of Kandelia candel. Avicennia marina had the worst winter resistance among the three species plants, Kandelia candel had the strongest, Aegiceras corniculatum was between the two, but was much better than Avicennia marina. Plant density also influenced growth rate.The accretion rates in different zones were measured by marked stump method. The results indicated that the average accretion rate in Quanzhou Bay estuary wetland is 6.74 cm yr-1, the fastest accretion occurred in midstream, while the slowest in the downstream. The accretion in winter, accounting for 48% of the year, is more than that in summer. During the rapid accretion period, the accretion rate in the high-middle tide area reaches an average of 10.64 cm yr-1. The accretion rate in the high tide level and low tide level is only a third of the high mid-tide level. The accretion rate are different under different vegetations, the lowest rate occurs under Spartina alterniflora, while the highest rate occurs under Kandelia candel, up to an average of 10.40 cm yr-1. The temporal and spatial variation of accretion rate in Quanzhou Bay estuary wetland was related to the hydrodynamics variation. Vegetation variation also has impact on the hydrodynamic processes.To study the salinity variations of Quanzhou Bay estuary wetland, the salinity and pH values of top-soil (2-5 cm) under different vegetation at different elevation (high-mid tidal area and low-mid tidal area) from upstream, midstream and downstream of Luoyang River, were measured. The average soil salinities in different sections of Quanzhou Bay estuary wetland are spatially different and ranges in a large variation span, from 10.8 to 17.0 ms per cm. The salinity in soil is increasing in order:upstream> midstream>downstream. The average pH value in soil of Quanzhou Bay estuary wetland was 6.92-7.66, with a small variation range. The difference between the soil pH values from upstream and mid-stream was slightly and no significant. The pH values in soil from downstream are higher than those of the upstream and midstream. The soil salinities in some sections or tidal levels were positively correlated with the pH values significantly, the desalinated by different plants in Quanzhou Bay estuary wetlands were studied. The results showed that the salinity of the new alluvial without plants and the bare soil (the plants was destroyed) was higher than that of the soil under plants. The farther away from the basal main stem, the greater the salinity was. The desalination of plants in Quanzhou Bay estuary wetland was take placed. The order of plants desalination capability was as following:Kandelia candel> Spartina alterniflora> Aegiceras corniculatum> Avicennia marina. There was significant correlation between the pH and salinity in some zones. The correlation between the pH and salinity in most zones was weak. It indicated that soil desalination and acidification had poor correlation, or even were two independent processes in most zones.The characteristics of spatial-temporal distribution of ammonium nitrogen, nitrate nitrogen, available phosphorus, copper, zinc, iron and manganese in soil in different districts (upstream, midstream and downstream) and under different vegetations of Quanzhou Bay estuary wetland were studied. The result showed that the content of ammonium nitrogen of soil in spring was higher than that in other seasons; it was associated with the great urease activity of soil in spring. The content of ammonium nitrogen was highest in soil-layer of 30-40 centimeter in Centenary Aegiceras corniculatum, as the soil-layer was the dense distribution of roots system. The content of ammonium nitrogen and available phosphorus were related to temperature and plant biomass. The proportion of ammonium nitrogen to nitrate nitrogen of soil in Quanzhou Bay estuary wetland was between 1.05 and 1.97, and the soil ventilation influenced the proportion. The proportion of available nitrogen and available phosphorus of soil in Quanzhou Bay estuary wetland was between 0.56 and 1.52, the nitrogen-limited status of soil was more serious along with plants growing. The spatial-temporal variation of available copper, zinc, iron and manganese was significant, and this was involved in the absorption on nutrition elements by plants, the variation of seasons and the ventilation of soil. the composition patterns and stoichiometry of nutrition elements in soil of Ouanzhou Bay and estuary wetland had diversity. The wetland soil transformed from phosphorus-abundance to phosphorus-limitation owing to the variation of the vegetation. Stoichiometry of nutrition elements depended on the plant species, the element types and the variation of microenvironment. The input of pollutant also had some influence on the composition and content of nutrition elements in soil. The diversity of mineral nutrition elements was the foundation of the plants'adaptability to environment.The variations of the activities of urease, phosphatase, catalase (CAT) and polyphenol oxidase (PPO) at different soil depth, under different vegetation, in different seasons and from different district of Quanzhou estuary wetland were studied. The results revealed that the urease and phosphatase activities from summer (spring) were higher than these from winter (autumn). In the same season, the soil urease activity was significantly different under different plant species. The activity of urease in soil with vegetation was higher than that with no vegetation. The urease activity of Spartina alterniflora rizhozsphere soil was the highest. The order of the phosphatase activity in soil under different vegetation was as following:Spartina alterniflora> Centenary Aegiceras corniculatum> Kandelia candel> Avicennia marina> Aegiceras corniculatum> Bared land> new alluvial without plants. The soil urease and phosphatase enzyme activities got lower along with the increasing soil depth no matter with or without vegetations. The seasonal variation of CAT was as following:spring> autumn> winter> summer. In winter, the variation of CAT activity from different stream was greatly significant, the soil CAT activity from upstream was the lowest and that from midstream was the highest. The seasonal variation of soil CAT activity from Avicennia marina rhizosphere was not significant and that from Centenary Aegiceras corniculatum rhizosphere was the highest in winter. The seasonal variation of soil PPO activity was significant and the order of the activity was as following:summer> winter > spring> autumn. Spatially, the order of the soil PPO activity from upstream was as following:spring> summer> winter> autumn; that from the mid-stream was as following:spring> summer> autumn> winter and that from the downstream was as following:summer> winter> autumn> spring. The variation of the PPO activity from different vegetation rhizosphere was significant. There was a highest enzyme activity in bare soil in spring. Comparing with other vegetations, the soil PPO activity from Spartina alterniflora rizhozsphere was high. The variation patterns of the soil CAT activities along with the soil depths under different vegetation were involved in the roots architecture and oxygen supply by plant roots. The variation patterns of the soil PPO activities along with the soil depths under different vegetation were involved in the amount of the dead roots. The negative correlation between the activity of catalase and polyphenol oxidase in soil of Quanzhou Bay estuary wetland was weak (R2=0.036, n=770, p<0.01). In addition, the correlation between soil enzyme activity and nutrition elements in Quanzhou Bay estuary wetland were analyzed. The result showed that the soil in Quanzhou Bay estuary wetland was nitrogen and phosphorus co-limited. The response of soil enzymes on nutrient elements varied with the vegetations. The mechanism on the plants'adaptability to the wetland environment alternately dried and immersed varied with the plant species. The diverse patterns will influence the biogeochemical circles of soil carbon, nitrogen and phosphorus.The characteristics of chlorophyll fluorescence and photosynthesis of these dominant plants, Aegiceras corniculatum, Kandelia candel and Avicennia marina, in the wetland from different streams at different times were studied. The results showed that mature Aegiceras corniculatum, Kandelia candel and Avicennia marina were provided with good adaptability. The photosynthetics of mangrove Aegiceras corniculatum, Kandelia candel and Avicennia marina at downstream in Quanzhou Bay estuarine wetland were measured, and the relationship between the net photosynthetic rates of these plants and the climatic factors were analyzed. The results had shown that the diurnal variation of net photosynthetic rates of three species of plants were three-peak curve due to tidal action. The order of the average daily net photosynthetic rate was as following:Avicennia marina>Aegiceras corniculatum>Kandelia candel. The net photosynthetic rate of the plants was significantly correlated with their own physiological factors. There was a significant negative correlation between the net photosynthetic rate of the plants and the internal CO2 concentration, especially. The impact of stomatal conductance on the photosynthesis varied with plants. The net photosynthetic rates of Aegiceras corniculatum and Avicennia marina were significantly affected by stomatal conductance, and that of Kandelia candel was not affected. It was found that Avicennia marina had the adaptation to high salt environment, and sensitivity to flooding. But, Kandelia candel had the adaptation to tide changes, and sensitivity to high salt environment. The adaptation to high salt environment and flooding of Aegiceras corniculatum was intermediate between Avicennia marina and Kandelia candel.Finally, the principles of the selection on mangroves species, which include cold-resistance, toward-sea, and ecological security based on above results. The suggestion on the selection and configuration of mangrov species in the mangrove afforestation was put forward.
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