Study And Practice On Ecological Engineering Of Bird Habitat Reestablish On The Intertidal Flats In The Yangtze Estuary

Based on the knowledge about functions of the wetland ecosystem at the Yangtze Estuasy wetland ecosystem, the experiment on wetland birds' habitat construction has been conducted in 2005-2007. The change of key components of the habitats before and after this experiment was analyzed, including vegetation, macro-invertebrates, fishes and birds as effects of the construction.Major results of this study were:(1) The wetland vegetation changes greatly after the habitat constructionThe importance value of dominate species in the experimental area I had changed greatly during the period; before habitat had been constructed, its importance value was 0.632, while the other species were less than 0.05.and in 2006, the first year of habitat had been controlled, the importance values of Carex scabrifolia (0.024 to 0.148), Echinochloa crusgalli vac.mitis (0.039 to 0.151) and Inula linariaefoia (0.013 to 0.142) increased greatly, which become the dominant species. In 2007, the importance value of scabrifolia (0.327) increased, which was the most dominant specie in this area, the following one was linariaefoia (0.219) whose importance value increased, and the important value of crusgalli var.mitis (0.036) decreased quickly. The similar situation happened in the experimental area II. In a conclusion, the changes of vegetation growing in the experimental areas improve their landscape complexity, which is benefit for birds hiding.(2) The macro-invertebrate community structure has been restored quickly during the construction of birds' habitats.Due to the disturbance brought by the construction in 2006, almost macro-invertebrate communities reduced sharply. One month after the construction, both abundance and biomass were 0. After that, their abundance, biomass, Shannon-Wiener index and Margalef index increased fast. In the later spring, the abundance of the experimental area I was more than the control site, but the biomass was less than the control one. The changes of macro-invertebrate communities showed the close relationship with the seasondity in the first year. And the changes of macro-invertebrate communities were similar in the experimental area and control site. The research results of two years exhibit that the restoration of biomass was the slowest among the changes of macro-invertebrate communities, and it can be expected that, the macro-invertebrate communities tended to be stable after this disturbance(3) The function of natural bait retention is obviousFor the formation of water surface by this experimental engineering, 17species of fish of 5 families (11 Cyprinidae species) and 2 crustacean species have been stranded through tides, which increased the predation chance and prey biomass of birds. Both of the abundance and biomass of fish after the tidal generation engineering were more than the ones before retention, which was enough to show the function of natural bait retention of this experimental birds' habitat. It offers a new method for attracting wetland birds on tidal flat wetland, and should be the special technique that is suitable in building tidal flat wetland birds' habitats.(4) The various of habitats supports more birdsAfter the construction of the experimental area I , the original tidal flat wetland which was dominated by australis community changed to the compound wetland birds' suitable habitat which was composed by water surface of 40%, bare land of 30% and vegetation of the rest 30%. The data of 2006 showed that the species and total amount of shorebirds (Charadriiformes and Ciconiiformes) and other birds were apparently more than the ones of conrrol site, 56 species had been recorded in the experimental area I, which was 56% more than the species recorded in the control one.After the construction of the experimental area II, the compound wetland birds' suitable habitat was composed by water surface of 10%, bare land of 70% and vegetation of the rest 20%. The data in April and May of 2008 showed that 20 species were recorded in the second experimental area II, including 11 wading birds, meanwhile, only 9 species were recorded in the control site, including 1 wading bird, the similar data happened in the experimental area I, 22 species were recorded in this area, and including 9 wading birds. The ratios of wading birds occupying the total one of the experimental areas I and II were 68.9% and 78.3% respectively, which shows the approaching effect of both experimental habitat. It's conduded that through building the tidal habitats for birds, the rechiness and diversity of wetland birds increase, so that the ecological sfunction of this area will be improved.