| This paper focuses on the early artificial recovery period of the mangrove wetlands in Hezhoubei; carries out the investigation on the community dynamics after the invasion by Mikania micrantha, seasonal dynamics of aquaculture wastewater flowing through the Sonneratia apetala plantation and soil vertical dynamic of Bruguiera gymnoihiza plots, Kandelia candel plots (After the death of mangrove plants) and Stable habitat of Sonneratia apetala plantation. Surveying of water quality, soil and plant communitiesof the mangrove wetlands. Combining indoor experimental analysis, we conclude the following:The number of the species varied sharply as seasons change and the species composition is unstable. Mikania micrantha invasion directly increased the volatility of the seasonal change of the number of species, the dominance index of the B. gymnoihiza plantation and K. candel plantation reduced directly over time, the changes were independent according to different seasons, and the survival rate reduced due to invasion of M. micrantha and other poaceae grasses. The dominance index of S. apetala plantation varied markedly. The invasion species of Poaceae and Compositae can not settle. S. apetala plantation provided a good stable environment for other Mangrove regeneration.The soil texture was pink sticky soil at the early period of mangrove plantation. The main content of particles was greater than0.02mm in subsoil. The main content of particles was smaller than0.02mm in topsoil. The percentages of sand (2-1mm), silt (0.05-0.002mm) and clay (<0.002mm) were not significantly different between plots and mud flat. Soil PH was negatively correlated with soil depth. The pH in Mangrove plots at the initial stage was less than plots of the mudflat. The subsoil and topsoil organic matter contents were the S. apetala Plantation> K. candel Plantation> B. gymnorrhiza Plantation> mudflat, and soil organic matter content decreased with increasing soil depth. Available nitrogen content in the subsoil is higher than that in the topsoil content. The subsoil and topsoil available P content of K. candel> B. gymnorrhiza> the S. apetala> mudflat. The S. apetala plots and Beach (control) available phosphorus content is at the similar level. At the same time, the subsoil available phosphorus content is higher than that of the the topsoil. And the vertical distribution of terrestrial forest soil nutrients, there are significant differences. Potassium subsoil and topsoil content in K. candet>S. apetala> mudflat. Moreover, the available K content in subsoil is higher than that in the topsoil, at the same time, subsoil the available K content in subsoil is relatively large different from topsoil of S. apetala. Soil water-soluble salt content was12.13-18.08g/kg in plantation mangrove. The trend of soil salt content of the topsoil and subsoil was S. apetala> K. candet>B. gymnorrhiza>mudflat. the salt content in the topsoil was greater than that in subsoil. Deposition variation of the various plots showed that siltation in winter and spring, erosion in summer and autumn. Erosion and deposition in the each plot were not apparently different. December and March were positive, June and September were negative. Compared with the mudflat, flushing amount in tidal mudflat is significantly lower.Mikania micrantha invasived after B. gymnorrhiza, K. candel planted. High organic environment for the growth of Mikania micrantha provided good conditions, the rapid growth of Mikania micrantha exacerbated by the death of the mangrove species, then a vicious circle in the plot, the factors are basically no difference ddition to the PH value of S. apetala form the land forest to the helin. Thus, the chemical properties is not infunlunces by the changes of horizontal distance. Various factors was significant as soil depth changes, organic was very significantly.The pH value of the sewage in S. apetala plantation decreased significantly at the flowing distance increased. Turbidity range was9.9-24.8degrees, and it increased as the distance increased. Turbidity in December,2010was significantly different from those of the other days. Suspended solids in the control area was not apparently different from that in the upstream contaminated area, while significantly reduced in the nearby S. apetala plantation. Chemical oxygen demand in December of2010is significantly higher than in other months, indicating that pollution is more serious in winter. At the same time, the chemical oxygen demand was lower in S. apetala plantation than other two plots, decreasing by36.5%and45.2%respectively. The trend of BOD content in the S. apetala plantation was significantly lower than that in the other two areas and was significantly different from those in December of2010. The trend of BOD content in the S. apetala plantation in September of2011decreased as the distance increased, due to self-purification capacity of water bodies. Inorganic total phosphorus content decreased with distance increased in the S. apetala plantation. Inorganic total phosphorus content was0.013-0.165mg/L. The average nitrogen content in winter was significantly higher than that in the other seasons. The total phosphorus content was significantly lower than that in the other two areas and the difference was the most significant in December of2010. The specific changes were December of2010> March of2011> September of2011> June of2011. pH, turbidity, COD, BOD content were referred to the Sea Water Quality Standard GB3097-1997, indicating that organic pollution is very serious in the Modaomen in Zhujiang estuary waters, belonging to the fourth water quality class (sea port waters, ocean development, operation area) BOD and COD≤5mg/L, while the content in plots in was higher than this water.The N/P ratios was relatively high in seasons and minimun to19.96in winter. It indicated that the N content was high in this area. The restriction extent of the two kinds of nutrients was different in different seasons, while the N content was highest in autumn. The number of seedlings increased in Long-range sewage outfall, closer sewage outfall, outfall of S. apetala. The species number increased in S. apetala plantation. The height of the seedlings decreased in sewage outfall of A. ilicifolius seedlings. The number and height decreased of Trefoil rotenone, Cyperus malaccensis and water hyacinth in sweage outfall. The variation of the number of seedlings was less of A. carniculatum. |
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