Analysis On Land Use Dynamics And Assessment Of Wetland Ecological Restoration At Reclaimed Area Of Lingang New City, Shanghai

Coastal wetland is a transitional zone between ocean ecosystem and terrestrial ecosystem, which plays a significant role in maintaining ecological balance and providing habitats for animals and plants. The reclaimed area of Lingang New City in Shanghai is an important coastal wetland at Yangtze estuary and a crucial feeding stop on the bird migratory routes at Asia-Pacific region. In the past two decades, two large-scale reclamations on tidal flats were conducted at Lingang New City, and the flats above the elevation of Om had been enclosed entirely for many kinds of land use. The human disturbance of land use activities resulted in the degradation or loss of the wetland, causing the suitable habitats (especially for water birds) lesser and lesser, and even threatening the ecosystem health of the wetland. So, in order to optimize the land use of the reclaimed area and promote the sustainable economic and social development in the region, it is necessary to study the land use dynamics and evaluate the avian habitats ecological restoration.In this research, in order to analyze the land use dynamics of the reclaimed area at Lingang New City, the satellite images of1990,2003,2008and2010were interpreted based on the collection of historical data and field trip. Then, the vegetation, water quality and soil were measured from August2009to June2010to analyze and evaluate the restoration work at the reclaimed area of Lingang New City. Finally, this research gives the land use ecological optimization advices, according to the analysis on land use dynamics and the assessment of habitat ecological restoration.Results of the land use dynamics showed that in the last two decades of the reclaimed area, with the land use types and the proportion of human introduced landscapes increased, the areas of natural wetland landscapes showed an overall downward trend, mainly because of the increase of construction area and the cultivated land. The land use impact by external human interference was strengthened gradually. Landscape patch density, edge density and landscape diversity increased, and the patch shape was more complex and irregular. The landscape pattern became to be more fragmented as a whole. There is an urgent need for reasonable protection and optimal use of the local land resources.Assessment results of habitat ecological restoration showed that the growth of the native plant Phragmites australis had been improved significantly, and the qualities of water and soil had been improved to some extent. Moreover, the demonstration project had enhanced bird biodiversity. These results indicated that the ecological restoration project had got a preliminary and promising effect on the wetland dynamic conservation. However, in order to improve the quality of the avian habitats better, an integrated technique of cutting plus waterlogging should be taken to eliminate the invasive plant Spartina alterniflora and the scale of eco-aquaculture should be controlled.According to the results above, land use optimization advices are given as follows:1. Vegetation and water landscapes of core ecological source should be preserved; Vegetation and water landscapes, as well as bareland outside the core ecological source should be developed rationally; The scale and location of construction land and farmland should be restrained.2. Reconstruct tidal marsh environment at the reclaimed area of high ecological conservation value by means of nature and engineering; Plant Phragmites australis and Scirpus mariqueter to promote sedimentation and restore the natural tidal flat environment.